Funded Projects

2016 Funded Projects


Brendan J. Battersby, Ph.D., Research Director

Biomedicum Helsinki, Research Programs Unit-Molecular Neurology
University of Helsinki (Finland)
Principal Investigator Award –  2 years/$70,000

Investigating the Pathogenesis of C12orf65 Deficiency in Mitochondrial Translation and Mitochondrial Disease

The goal of this research project led by Dr. Battersby is to address a significant gap in mechanistic knowledge within the mitochondrial field- ribosome function and translation. The outcome of this work could provide unique insights into the broad range of mitochondrial disease symptoms that result from mutations in the C12orf65 gene.

Alessandro Bitto, Ph.D.,

Department of Pathology, University of Washington Medical Center (USA)
Postdoctoral Fellowship Award – 2 years/$70,000

Molecular Mechanisms for Suppression of Mitochondrial Disease by Acarbose,

Dr. Bitto, under the mentorship of Dr. Matt Kaeberlein, will evaluate an FDA-approved drug called acarbose for efficacy in a translational mouse model of Leigh Syndrome. The drug impacts mTOR signaling, an important mitochondrial function pathway whose understanding could open up a broad therapeutic strategy for mitochondrial disease.


CHAIRMAN’S AWARD

Nicola Brunetti-Pierri, MD, FACMG

Associate Investigator, Telethon Institute of Genetics and Medicine (Italy)
Small Clinical Study Award – 1 year/$25,000

Phenylbutyrate Therapy for Pyruvate Dehydrogenase Deficiency

This grant, winner of the 2016 Chairman’s Award for highest rated research proposal after peer review, is a clinical study of a new potential therapy for pyruvate dehydrogenase complex (PDHC) deficiency by lowering lactate levels. This project comes 5 years after Dr. Brunetti-Pierri received a UMDF grant to first test phenylbutarate on patient cells. Subsequent animal model studies confirmed the promising in vitro data that resulted from the first grant, and now a pilot clinical trial will be carried out across multiple centers in Italy. Positive results from the pilot study would lead to a larger study directed toward PDHC deficiency patients.

Adam Hughes, Ph.D.

Assistant Professor of Biochemistry, University of Utah School of Medicine (USA)
Principal Investigator Award – 2 years/$100,000

Quality Control of Unimported Mitochondrial Precursor Proteins

Utilizing yeast models, Dr. Hughes intends to explore the link between loss of mitochondrial membrane potential and mis-targeted mitochondrial proteins. That the accumulation of such proteins and their associated “waste disposal” is a source of mitochondrial pathology is a novel and intriguing premise that could open up many new avenues in future research.

Leo Nijtmans, Ph.D.

Radboud University Medical Centre, Nijmegen (Netherlands)
Principal Investigator Award – 1 year/$40,000

Mitochondrial Complexome Profiling Provides a Novel Tool to Diagnose and Understand Complex I Deficiency

Complex I disorders are some of the most common types of mitochondrial disease. Dr. Nijtmans will utilize a profiling technique to study protein interactions within Complex I using patient cell lines. The results will provide insight into Complex I assembly and function, and could ultimately lead to new therapeutic targets for investigation.

George A. Porter, Jr., MD, Ph.D.

Assistant Professor, Department of Pediatrics, Division of Cardiology, University of Rochester Medical Center (USA)
Principal Investigator Award – 2 years/$100,000
Manipulating the Permeability Transition Pore to Ameliorate Neonatal Heart Failure

Many types of mitochondrial disease have associated cardiomyopathies. In this translational research project Dr. Porter will test potential therapies for cardiomyopathies in a mouse model. Success in this project would initially open the possibility for treating neonates with bioenergetics disorders, and eventually have potential for more broadly treating mitochondrial disease patients with Complex I disorders.

Eric A. Shoubridge, Ph.D.

Professor and Chair, Department of Human Genetics, Montreal Neurological Institute, McGill University (Canada)
Principal Investigator Award- 2 years/$75,000
Interrogating the Mitochondrial Interactome Using BioID

Dr. Shoubridge’s project will identify functional networks within the mitochondria based on the analysis of protein-protein interactions. In addition to the potential for revealing new insights into mitochondrial disease, the availability of a mitochondrial protein interactome will be a generally useful resource for addressing basic questions regarding mitochondrial structure and function in both a normal and diseased state.

Zarazuela Zolkipli Cunningham, MBChB MRCP

Division of Neurology, The Children’s Hospital of Philadelphia (USA)
Small Clinical Study Award – 1 year/$25,000

Development and Validation of a New Outcome Measure in Mitochondrial Disease

 

Dr. Zolkipli Cunningham and collaborators aim to develop a new outcome measure for mitochondrial myopathy that is specifically designed for use in Phase II/III clinical trials. The patient perspective will be critical to the project, helping to ensure that meaningful measures are developed over the full range of disease state- from early ambulatory to late non-ambulatory. Recognizing the urgent need for improved clinical trial endpoints, the development of this scale will build upon existing scales and tools.

 

 

 

2015 Funded Projects

CHAIRMAN’S AWARD

John Christodoulou, Ph.D.
Children’s Hospital at Westmead
New South Wales, Australia.
Grant Award $100,000

“Utility of FGF21 and GDF15 as Diagnostic and Prognostic Biomarkers
of Mitochondrial Respiratory Chain Disorders.” 

Dr. Christodoulou will validate optimal methodology in a clinical diagnostic laboratory setting to determine the utility of measuring FGF-21 and GDF-15 as biomarkers of pediatric mitochondrial disease. This has become a major question in the field, as to how potentially useful in terms of sensitivity and specificity these biomarkers are for mitochondrial disease.

Daniel F. Bogenhagen, MD
Department of Pharmacological Sciences
Stony Brook University
Grant Award – $100,000

“Kinetics of Mitochondrial Complex Assembly.” 

Dr. Bogenhagen is utilizing mass spectrometry techniques to study the assembly map of the mitoribosome as well as the mitochondrial respiratory complexes. The improved understanding of both of these mitochondrial construction projects will enhance the diagnosis and future therapy of mitochondrial disorders.

Peter W. Stacpoole, MD, Ph.D.
Department of Medicine
University of Florida

Grant Award $24,898

“Validation of an Observer Reported Outcome (ObsRO) Measure of Home Functionality in Children with Pyruvate Dehydrogenase Complex Deficiency (PDCD).” 

Dr. Stacpoole, in response to a specific request from the FDA for information from the patient or patient family to aid in regulatory decisions, has developed an innovative computer tool to track home functionality of pediatric PDCD patients. The pilot study in 10 PDCD families will test the feasibility of the survey instrument and refine it as needed for its eventual use in a planned Phase III trial of dichloroacetate (DCA). If the trial shows DCA is found safe and effective, it could lead to this drug being designated as the first FDA-approved therapy for PDCD.

Dr. Atif Towheed, Ph.D.
Department of Pathology and Laboratory Medicine
Children’s Hospital of Philadelphia
Grant Award –  $70,000

“Allotopic RNA Rescue of LHON Mouse Model.”
The goal of Dr. Towheed’s work is to develop a novel gene therapy strategy for the treatment of Leber hereditary optic neuropathy (LHON) utilizing a mouse model developed in the labs of Dr. Douglas C. Wallace. If this therapeutic approach is successful it could inhibit the onset of the optic nerve pathology.

Sara M. Nowinski, Ph.D.
Department of Biochemistry
University of Utah
Grant Award – $70,000

“Characterizing the Function of the Atypical Mitochondrial Kinase ADCK3.”

The studies in Dr. Nowinski’s grant will improve the understanding of ADCK3 function in the synthesis of coenzyme Q and cerebellar ataxia. Additionally, better treatment strategies for mitochondrial disease could be developed in the future if new roles for ADCK3 are identified.

 

Anu Suomalainen Wartiovaara MD, Ph.D.
University of Helsinki, Finland.
Grant Award – $100,000

“Vitamins B as Therapy for Disorders with mtDNA Instability.” 

Dr. Suomalainen Wartiovaara will utilize a mouse model to build upon preliminary results indicating that vitamins B, especially B3 (Niacin) play key metabolism regulatory roles in patients with mitochondrial myopathies. Pre-clinical data generated in mice will inform the creation of a follow-up human clinical trial on the impact of Niacin supplementation for the alleviation of symptoms due to mitochondrial disease.
Project Descriptions on this webpage are provided by Steven G. Bassett, PhD

 

 

 

2014 Funded Projects

CHAIRMAN’S AWARD
Hubert Smeets, Ph.D.
Department of Genetics and Cell Biology
Maastricht University, The Netherlands
Grant Award Amount – $25,000

Dr. Smeet’s project is entitled “Development of an autologous myogenic stem cell therapy for carriers of a heteroplasmic mtDNA mutation, a proof of principle study.” Dr. Smeets  has developed a process using transplantation of a patient’s own muscle stem cells that have been freed of mitochondrial DNA mutations. The resulting formation of normal muscle fibers promises to set the stage for significant new therapies for mitochondrial disease.

Carlos Moraes, Ph.D.
Department of Neurology
University of Miami Miller School of Medicine
Grant Award Amount – $120,000

Dr. Moraes project is entitled   “Developing specific mitochondrial nucleases to eliminate mutant mtDNA.”  Dr. Moraes has developed a process for removing disease-causing mitochondrial DNA mutations from affected mitochondria.  Extension of this research seems likely to lead to the development of gene therapies for human mitochondrial disease.

 

Michael James Bell, M.D.
University of Pittsburgh
Grant Award Amount – $25,000

Dr. Bell’s project is entitled “Improving CNS delivery of brain antioxidants after acute metabolic decompensation in mitochondrial disease.” Dr. Bell will investigate a combination of two FDA-approved drugs for their effectiveness in treating children and young adults with Leigh’s Syndrome. This work has the potential to improve brain function in patients with a mitochondrial disease for which there are currently no proven treatments.

Francisca Diaz, Ph.D.
Department of Neurology
University of Miami Miller School of Medicine
Grant Award Amount – $80,000

Dr. Diaz’s project is entitled  “Modulation of GSK3 activity to maintain neuronal survival in complex IV deficient mouse.” Dr. Diaz is using a much studied mouse model in which a mitochondrial respiratory enzyme has been deactivated in nerve cells.  She will study the effectiveness of modulating glucose metabolism as a treatment for these mice, with the potential for extending this therapy to human mitochondrial disease patients.

Scot Leary, Ph.D.
Department of Biochemistry
University of Saskatchewan
Grant Award Amount – $120,000

Dr. Leary’s project is entitled  “Targeted delivery of copper to mitochondria: investigating its therapeutic potential for the effective treatment of patients with mutations in SCO1 and SCO2.”  Dr. Leary is investigating therapies for copper delivery to mitochondria in patients with impaired ability to synthesize a vital mitochondrial respiratory enzyme that requires copper as a building block. This research could lead to the development of early intervention therapies for mitochondrial disease.

Erin Seifert, Ph.D.
Department of Pathology
Thomas Jefferson University
Grant Award Amount – $120,000

Dr. Seifert’s project is entitled “Pathogenesis of myopathies caused by mitochondrial phosphate carrier mutations.”  Dr. Seifert is studying mutations that severely affect the delivery of phosphate for ATP synthesis in the mitochondria of skeletal muscle and the heart. This foundational research will provide new insights into important mechanisms responsible for mitochondrial disease.

 

 

2013

Chairman’s Award
James Stewart, Ph.D., Max Planck Institute for the Biology of Ageing, Cologne, Germany $90,000 for two years.

“Using mtDNA mutator mouse-derived lineages to generate mouse models of human mitochondrial diseases.”
The connections between genetic mutations and disease symptoms in human mitochondrial disease are not always clear. Two patients with the same mutation can have very different symptoms. More animal models of mitochondrial diseases are needed in order to address this question, allowing specific genetic and biochemical changes to be correlated with disease symptoms. Having strains of mice available that possess specific mutations of mitochondrial DNA, known to be associated with specific human mitochondrial disease will be especially useful.

Dr. Stewart and colleagues in Germany are conducting UMDF-funded research with mice that are prone to mutations in their mitochondrial DNA. They are able to use this system to generate families of mice that carry specific mitochondrial DNA mutations that lead to mitochondrial disease in the mice. Studying the biology of mice with specific mutations should significantly increase the number of available mouse models for human mitochondrial disease. Research with these animals will aid the development of new genetic models of human disease and also of new drug therapies. This will be especially important in finding treatments to improve skeletal muscle and heart function in mitochondrial disease patients.
Alberto Sanz-Monterro, Ph.D., University of Tampere, Tampere, Finland
$100,000 for two years

“A Genome-wide RNAi Screening to Identify New Genes Involved in Mitochondrial Diseases.”

Mitochondrial diseases are caused by numerous mutations of DNA residing in the nucleus or in the mitochondria themselves. And yet, many mitochondrial disease patients have not had a specific genetic mutation linked with their disease. This has only been accomplished for about half of all known mitochondrial diseases. Discovery of a specific mutation could help to identify the pathological changes that are occurring, leading to potential therapeutic interventions.

Dr. Sanz-Montero and colleagues at the University of Tampere in Finland are conducting UMDF-funded research using a well-understood fruit-fly model to discover previously unknown genetic defects that can cause mitochondrial disease. Locating genes similar to those in humans will provide insights into specific genetic processes responsible for human mitochondrial disease. Understanding the metabolic roles played by these genes will aid physicians in developing new treatments.

Gerald Shadel, Ph.D., Yale University
$90,000 for two years

“Characterization of disease-specific mitochondrial stress-signaling pathways in vivoas potential therapeutic targets for mitochondrial diseases.”

 

While it is known that certain genetic mutations are linked to specific mitochondrial disorders, the actual mechanisms and cell signaling pathways involved often remain unclear. The study of cell signaling involves discovering how cells regulate their function through specific communication channels. These channels can be disrupted during conditions of stress and disease. Gaining a clearer understanding of how signaling changes during the course of diseases provides important insight into how they might be treated.

Dr. Gerald Shadel and colleagues at Yale University are conducting UMDF-funded research to more fully characterize these signaling pathways. Employing genetic modifications in mice that impair the activity of specific mitochondrial components, they are studying how regulation of skeletal muscle, heart, and brain functions are affected. He will then extend these findings by looking for similar changes in cells derived from mitochondrial disease patients. This improved understanding of changes in cell signaling can lead to new treatment models for mitochondrial disease.
Rajesh Ambasudhan, Ph.D., Sanford-Burnham Medical Research Institute, La Jolla, California
$84,000 for two years

“A Human Reprogrammed-Cell Model of MELAS.”

MELAS is a severe mitochondrial disease that significantly impairs nervous system function, leading to recurring seizures and other disorders. While a number of mitochondrial DNA mutations have been linked to this condition, little research has been performed on the specific changes that occur in a MELAS patient’s affected cells. It has also been a challenge to develop effective therapies for the condition.

Dr. Rajesh Ambasudhan and colleagues are performing UMDF-funded research that involves obtaining skin cells from MELAS patients and reprograming them to become nerve cells that are grown in culture. No one could have predicted a generation ago that it would be possible to cause one kind of conversion of differentiated cell into another cell type. But this technology is being used in Dr. Ambasudhan’s lab today to provide important insights into mitochondrial disease. Once the skin cells have been converted to nerve cells in culture, they will have characteristics similar to the brain cells in a MELAS patient, with similar functional impairments. This procedure results in an unlimited supply of cells in various stages of the disease. Their use will enhance our understanding of mitochondrial dysfunction in MELAS, as well as other mitochondrial diseases, and will aid the development of treatments for these challenging disorders.
Natalie Niemi, Ph.D., University of Wisconsin, Madison, Wisconsin
$75,000 for two years

“Utilizing dynamically regulated phosphorylation as a means to modulate mitochondrial metabolism.”

Phosphorylation is a well-known mechanism for activating or inactivating enzymes in cells. Mitochondrial respiratory enzymes are at the heart of the energy metabolism that cells require for normal function. Abnormal changes in phosphorylation of these mitochondrial enzymes may be an important factor in mitochondrial disease.

Dr. Niemi and colleagues in the lab of Dr. David Pagliarini at the University of Wisconsin-Madison are conducting UMDF-funded research to study how phosphorylation is regulated in mitochondria. Her goal is to discover how impaired regulation contributes to the development of mitochondrial disease. This research could lead to new therapeutic options for mitochondrial disease patients.

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2013 Clinical Fellowship Training Award

Amel Karaa, M.D., Harvard Medical School and Massachusetts General Hospital
Boston, MA
$70,000 for 1 year

“Hypogonadotropic hypogonadism in mitochondrial disease: prevalence, phenotypic heterogeneity and hormonal spectrum variations in a tertiary hospital cohort.”

    

 

 

2013 UMDF Grant Recipients 

Chairman’s Award

James Stewart, Ph.D., Max Planck Institute for the Biology of Ageing, Cologne, Germany  $90,000 for two years

“Using mtDNA mutator mouse-derived lineages to generate mouse models of human mitochondrial diseases.”

By working with mice that are prone to mitochondrial mutations, Dr. Stewart will develop new genetic models of human disease. Once established, these mouse models can be used for the development of new drug therapies.
Alberto Sanz-Monterro, Ph.D., University of Tampere, Tampere, Finland
$100,000 for two years

“A Genome-wide RNAi Screening to Identify New Genes Involved in Mitochondrial Diseases.”

Dr. Sanz-Monterro will use a well-understood fruit-fly model to discover previously unknown genetic defects that can cause mitochondrial disease. Many mitochondrial disease patients have not had a specific genetic mutation linked with their disease, and this research will help to fill that gap.
Rajesh Ambasudhan, Ph.D., Sanford-Burnham Medical Research Institute, La Jolla, California
$84,000 for two years

“A Human Reprogrammed-Cell Model of MELAS.”

Dr. Ambasudhan will obtain skin cells from MELAS patients and reprogram them as nerve cells to be grown in culture. This “disease-in-a-dish” model will be used to gain insights into mitochondrial dysfunction in MELAS and other mitochondrial diseases.
Natalie Niemi, Ph.D., University of Wisconsin, Madison, Wisconsin
$75,000 for two years

“Utilizing dynamically regulated phosphorylation as a means to modulate mitochondrial metabolism.”

Dr. Niemi will study mechanisms that activate enzymes in the mitochondria, with the goal of understanding how this regulation is impaired in mitochondrial disease. This could lead to new therapeutic options for mitochondrial disease patients.
Alicia Pickrell, Ph.D., National Institute of Neurological Disorders and Stroke, Bethesda, Maryland
$75,000 for two years

“Therapy for mitochondrial diseases: an investigation into the potential to stimulate Parkin-mediated mitophagy.”

Dr. Pickrell is studying the effects of the drug Rapamycin on the removal of abnormal mitochondria from cells in mice. This FDA-approved drug has the potential to selectively eliminate dysfunctional mitochondria in humans, helping to restore normal energy metabolism in mitochondrial disease patients.

 

2012 UMDF Grant Recipients
 

Carla Giordano, M.D., Ph.D.
University of Rome
2012 Chairman’s Award – $108,000

“Estrogen mediated regulation of mitochondrial biogenesis and functions: possible therapeutic implications for Leber’s hereditary optic neuropathy.”

Leber’s hereditary optic neuropathy (LHON) is the most common mitochondrial disease and causes rapid onset of blindness. Patients with the specific mitochondrial DNA mutations that cause LHON experience progressive loss of optic nerve function. This cranial nerve conducts information about what we see to the brain. The first symptom a patient notices is blurred vision, which eventually leads to severe visual impairment in one eye and is followed a couple of months later by vision loss in the other eye. Effective and reliable remedies have not been developed for the treatment or prevention of this disease. Since over half of individuals with one or more of the mutations that cause LHON do not actually have the disease and are asymptomatic, it might be possible to find therapies that would prevent its ultimate development.

Dr. Giordano and associates at the University of Rome are conducting UMDF-funded research using phytoestrogens with a cell model of LHON. Phytoestrogens are plant-derived compounds with estrogenic properties that could potentially enhance mitochondrial energy metabolism in the cells. Establishing that these compounds are effective in the cell model could lead to therapies that would not only treat patients with the disease but might prevent its development in unaffected carriers. The research group is also studying a population of female LHON patients to determine how the timing of disease onset in these women correlates with their reproductive status. Taken together, their findings could contribute to the development of therapies for a mitochondrial disease that has previously been untreatable.

William James Craigen, M.D., Ph.D.
Baylor College of Medicine
$100,000

“Testing Gene Therapy in an Animal Model of Mitochondrial Respiratory Chain Disorders.”

The respiratory enzymes in the mitochondria are responsible for converting energy derived from food to ATP, a form of energy that is used by the cells. Manufacture of these enzymes follows a complex set of instructions contained in DNA found in both the cell’s nucleus and in the mitochondria themselves. Different mitochondrial diseases can be caused by DNA mutations that lead to an inability to make the enzymes necessary for normal ATP synthesis. Gene therapy, in which the correct DNA sequences have been provided to cells containing mutated DNA, has proven successful in the laboratory in reversing conditions such as Type I diabetes in mice. Does it hold promise for the treatment of mitochondrial disease as well?

Dr. Craigen and colleagues at Baylor College of Medicine are conducting UMDF-funded research to investigate gene therapy as a potential treatment for mitochondrial disease. They are working with a mouse model of a specific DNA mutation that impairs the function of a mitochondrial respiratory enzyme known as Complex I. They are developing procedures in which viruses will deliver the correct genetic information to these mice with defective mitochondria, in an attempt to greatly improve their energy metabolism. The viruses they are using are especially effective at targeting cells in the brain, heart, and skeletal muscle, all organs that can be severely impaired in some mitochondrial disease patients. Positive results could ultimately lead to the development of an effective gene therapy for mitochondrial disease.

Mariana G. Rosca, M.D.
Case Western Reserve University.
“Rescuing complex I defective mitochondria and target organs with methylene blue.”
$100,000

She is developing a treatment that could bypass a defective mitochondrial enzyme, enhancing energy metabolism. Improving the performance of mitochondria in this way could address a defect that is responsible for a third of all mitochondrial disease cases.

Javier Torres-Torronteras, Ph.D.
Vall d’Hebron Research Institute, Barcelona, Spain.
“Preclinical studies for the gene therapy of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). Long-term follow-up and use of adeno-associated viral vectors.”
$93,000

As an idea first proposed over 40 years ago, gene therapy was fairly straightforward to envision but proved difficult to implement. It was suggested that viruses could be used to transfer DNA segments into the cells of individuals who were either missing specific sets of genetic information or had incorrect information. Viruses are known to operate by inserting their own DNA into the nuclei of human cells and then redirecting their activities towards making more viruses. Why not manufacture a virus containing DNA that could replace mutated DNA in cells, restoring their normal function? And why not use this therapy to treat mitochondrial diseases?

Dr. Torres-Torronteras and colleagues at his institution’s Laboratory of Mitochondrial Disorders are doing just this by conducting UMDF-funded research to investigate the effectiveness of a gene therapy developed in his lab for use in mice with mitochondrial disease. They are especially interested in developing treatments for MNGIE, a progressive degenerative disease of the gastrointestinal tract for whichthey have developed two virus-delivery models.This research will aid in determining the best approaches for treating this and other human mitochondrial diseases with gene therapy.

David A. Sinclair, Ph.D.
Harvard Medical School.
“Ultra-high-throughput screening for mitochondrial enhancers as novel targets for treating mitochondrial diseases.”
$80,000

The variety of symptoms experienced by mitochondrial disease patients have in common a decreased capacity to make energy available to their cells in the form of ATP. Low cellular energy levels can seriously impair function in a number of organ systems, notably the musculoskeletal and nervous systems. Gaining detailed insights into how mitochondrial energy production is regulated in these organs will likely lead to important new treatments that could restore ATP synthesis in patients to more normal levels. This is a complex topic that researchers are investigating in both healthy individuals and patients. Regulation of the synthesis of mitochondrial membranes, the dynamics of how mitochondria are distributed throughout the cell, the rates of mitochondrial fusion and fission, and factors that promote either the manufacture or breakdown of mitochondria are all promising areas of research.

Dr. Sinclair and colleagues at Harvard Medical School are conducting UMDF-funded research togain a wide-ranging view of how mitochondrial energy metabolism is regulated. They are currently screening over 15,000 genes for their ability to enhance production of ATP. Understanding how these genes regulate energy metabolism will prove essential in developing new approaches to the treatment of mitochondrial disease. His lab is also evaluating thepotential of a large number of molecules to enhance energy metabolism in cell culture models of certain mitochondrial diseases, such assuch as LHON and MELAS.This large-scale approach could lead to the discovery of new and effective treatments for these and other forms of mitochondrial disease.
Nuno Raimundo, Ph.D.
Yale University School of Medicine.
“Mechanisms and treatment of mitochondrial deafness.”

$50,000

Aminoglycosides are powerful antibiotics that are used successfully to treat complex infections that might not respond to other more commonly prescribed antibiotics. Unfortunately, a serious side effect of these drugs is the potential to cause hearing impairment due to their ototoxic properties. Ototoxicity can result in destruction of the hair cells in the inner ear that are responsible for hearing, leading to irreversible deafness. Certain individuals possess a mitochondrial DNA mutation that makes them more susceptible to this drug-induced deafness.

Dr. Raimundo and colleagues at Yale University School of Medicine have developed a mouse model with a mitochondrial mutation that reproduces the symptoms and pathophysiology of aminoglycoside-induced deafness, causing the same progressive hearing loss experienced by humans. They are conducting UMDF-funded research with these animals to test potential therapies that might prevent or lessen hearing loss. In one part of the project, animal diets are supplemented with various antioxidant compounds, such as alpha-lipoic acid and coenzyme Q10, with follow-up assessment of hearing after several months of treatment. The development of effective therapies for this condition would not only help prevent hearing loss in patients with the mitochondrial mutation, but could also provide fundamental insights into the pathological mechanisms of other mitochondrial diseases.

 

 2011 UMDF Grant Recipients

Brett Kaufman, PhD
Department of Animal Biology University of Pennsylvania

2011 Chairman’s Award – $120,000
“Regulatory mechanisms governing TFAM-mediated mtDNA copy number control”

Mitochondrial DNA contains the information for making several components of the respiratory enzymes in mitochondria. Normal function of these enzymes is necessary for mitochondria to make ATP available to cells for energy-requiring processes. While normal mitochondria contain a few dozen copies of mtDNA, many mitochondrial diseases result from an abnormally low number of mtDNA copies, through a process known as depletion. Mitochondrial transcription factor A (TFAM) is a gene that controls transcription of mtDNA and regulates the number of mtDNA copies in mitochondria. It has been suggested that increased activity of TFAM may have a protective effect in certain diseases.

Using UMDF-provided research funds, Dr. Kaufman and co-workers are researching the regulation of TFAM to acquire insights into how it maintains the mtDNA copy number. Perhaps TFAM can be stimulated to augment the number of mtDNA copies in organs affected by mitochondrial disease. His research could lead to therapies that would increase the number of copies of normal mitochondrial DNA in patients with specific types of mitochondrial disease.


Nicola Brunetti-Pierri,  MD
Telethon Institute of Genetics and Medicine
Fondazione Telethon,
Rome, Italy

2011 Chairman’s Award – $120,000
“Therapeutic Interventions for Pyruvate Dehydrogenase Deficiency.”

A key step in mitochondrial energy metabolism involves the three-carbon molecule known as pyruvate. The mitochondrial enzyme pyruvate deydrogenase complex (PDHC) plays an important role in the multi-step process of deriving energy from the food that we eat and ultimately transferring it to ATP. Impaired function or lack of PDHC results in conversion of unmetabolized pyruvate to lactic acid. The resultant lactic acidemia in turn can cause a variety of progressive neurological disorders. The prognosis for individuals with PDHC deficiency is poor and effective treatments are not available.
Dr. Brunetti-Pierri and co-workers are conducting UMDF-funded research to investigate the drug phenylbuturate as a treatment with the potential for enhancing the activity of the remaining PDHC in mitochondria deficient in the enzyme. Developing safe and effective treatments for PDHC deficiency could enhance ATP production and diminish lactic acid buildup in some mitochondrial disease patients

Miguel Garcia-Diaz, PhD
Department of Pharmacological Sciences
Stony Brook University, New York

Grant Award $100,000

“Deficiencies of tRNA maturation and the pathogenesis of mitochondrial diseases.”

Manufacture of the enzymes responsible for energy metabolism in mitochondria relies upon specific transfer RNAs (tRNAs) made by the mitochondria themselves. Mitochondrial tRNAs are responsible for delivering the amino acids used as building blocks for ATP-producing respiratory enzymes. Genetic mutations in mitochondrial DNA can adversely affect the assembly of these enzymes. Mutations impacting the synthesis of just one mitochondrial tRNA cause the majority of the cases of the mitochondrial disease MELAS, impairing the ability of mitochondria in multiple organs to make ATP.

Dr. Garcia-Diaz and colleagues are conducting UMDF-funded research to study the production of mitochondrial tRNAs. Because these molecules play an essential role in the synthesis of the energy-producing enzymes in mitochondria, this research will provide fundamental insight into pathological processes responsible for mitochondrial disease.

His research could lead to therapies that would increase the number of copies of normal mitochondrial DNA in patients with specific types of mitochondrial disease.

Ying Dai, MD, PhD
Department of Neurology
Beth Israel Deaconess Medical Center, Boston, MA

2011 Grant Award – $80,000

“Driving Selection Against Heteroplasmic Mitochondrial DNA Mutations by Enhancing Mitophagy.”

While most of the genetic information required for manufacture of a cell’s mitochondria is found in the DNA of the cell’s nucleus, a small portion of that information is contained in the mitochondria themselves. Mitochondrial DNA (mtDNA) has a high mutation rate and only a single enzyme, polymerase-gamma (POLG), is available to make the necessary repairs. Mutations in POLG can impair its ability to mend damaged mtDNA, leading to accumulation of mtDNA mutations, deletions and depletion that account for a significant number of mitochondrial diseases.

Dr. Ying Dai and colleagues are conducting UMDF-funded research directed towards developing a mechanism whereby mitochondria with abnormal mutated mtDNA could be eliminated from cells, with the goal of restoring normal function. Mitophagy is a cellular process in which defective mitochondria are degraded. Their goal is to develop a means of stimulating mitophagy in their research model in order to cause preferential elimination of mitochondria harboring high levels of the mtDNA mutation due to defective POLG. This could potentially lead to therapies that would restore normal energy metabolism in mitochondrial disease patients.
Cornelius Franciscus Boerkoel, MD, PhD
Department of Medical Genetics, University of British Columbia

2010 Research Award: $130,348

“Spinocerebellar ataxia with axonal neuropathy: defining the mitochondrial component.”
Ataxia, a general term for loss of muscle coordination during voluntary movements, can have numerous causes, either temporary or permanent. An inherited disease that progressively worsens over time, spinocerebellar ataxia results in part from degeneration of the cerebellum, a brain region that functions behind the scenes to ensure that the muscles of the arms and legs are working together harmoniously. Because neurons in the cerebellum and other brain regions are lost, the patient experiences increasing clumsiness and unsteadiness.

Dr. Boekoel and associates are conducting a UMDF-funded investigation of the role played by a mutated mitochondrial DNA-repair enzyme in the development of the progressive loss of coordination and mobility in patients with a specific type of spinocerebellar ataxia. In a related project, they are also assess the effectiveness of antioxidant therapy in reversing the effects of the enzyme mutation linked to the disease.

 

Robert E. Jensen, PhD
Department of Cell Biology, Johns Hopkins University

2010 Research Award: $110,000

“DMCA and Barth Syndromes- similar diseases caused by defects in mitochondrial protein import?”

The mitochondrial disease known as Barth Syndrome diminishes the capacity of cardiac (heart) muscle to pump blood. Linked to abnormalities in cardiolipin, an important component of the mitochondrial inner membrane, the disease significantly impairs mitochondrial energy metabolism leading to a seriously weakened and dilated heart. DCMA (dilated cardiomyopathy with ataxia) has a similar effect on heart function and yet seems to have a completely different mechanism, impaired transport of a mitochondrial protein. The two diseases result in similar types of cardiac dysfunction resulting from abnormal mitochondrial metabolism and yet apparently have different causes.

In a UMDF-funded project, Dr. Jensen and associates are comparing the cellular disease mechanisms of Barth Syndrome and DCMA. Discovering the mitochondrial defects that the two diseases have in common will provide important insights into metabolic impairments that may be common to a number of mitochondrial diseases.

 

Ingrid Tein, MD

Division of Neurology, Hospital for Sick Children, Toronto, Canada

2010 Research Award: $75,000

“Pilot study to investigate the efficacy of L-arginine therapy on endothelium-dependent vasodilation & mitochondrial metabolism in MELAS syndrome.”

MELAS is a mitochondrial disease that, among other effects, severely compromises function of the nervous system. The “stroke-like episodes” experienced by patients can lead to severe headaches, seizures, and temporary weakness on one side of the body. A possible cause of these devastating symptoms is a sudden decrease in blood flow to the brain. Development of therapies to restore blood flow could greatly improve symptomatic treatment of this disease.

Dr. Tein and associates are conducting a UMDF-funded investigation to determine the underlying vascular pathology of the stroke-like episodes associated with MELAS. Using non-invasive imaging, she is developing a procedure for detecting impaired blood flow to specific brain regions. This technique will then be employed to determine whether brain circulation improves in patients given oral doses of the amino acid L-arginine, which is known to dilate blood vessels, increasing blood flow to the brain.

 

Christoph Handschin
University of Basel, Switzerland

2009 Research Award: $130,000

“Mitochondrial dysfunction, exercise intolerance and myopathy in skeletal muscle-specific PGC-1α-deficient mice.”
Making the genetic information contained in DNA available for use by cells requires an initial step called transcription, in which a molecule known as RNA is synthesized. RNA embodies the original DNA message in a form used by cells to direct the manufacture of proteins. PGC-1α is a regulatory molecule known to activate synthesis of RNA that will lead to proteins important for normal energy metabolism in skeletal muscle. This transcriptional activator promotes the production of proteins that enable muscle cells to respond to exercise by increasing their capacity for aerobic ATP synthesis.
Dr. Handschin and colleagues at the University of Basel in Switzerland are conducting UMDF-funded research with mice that are deficient in PGC-1α. These mice experience skeletal muscle dysfunction similar to that associated with mitochondrial diseases in humans because the mice are missing this important regulator of the formation and activity of mitochondria. Studying the ways in which muscle function is impaired when PGC-1α occurs in abnormally low levels will provide insight into its potential as a target for treatment of mitochondrial disease.

 

Michael P. Murphy
Medical Research Council, Dunn Human Nutrition Unit, Cambridge, UK

2009 Research Award: $110,000

“Development of a Novel Mass Spectrometric Approach to Measure Mitochondrial Oxidative Damage In Vivo.”
Mitochondria contain the enzymatic machinery for production of ATP in the presence of oxygen, the method that makes the largest amount of ATP available to cells. This aerobic energy metabolism comes at a price, however, because it also results in the generation of reactive oxygen species (ROS). Free radicals and other ROS damage cells by removing electrons from cell components. Mitochondria with impaired energy systems do not use oxygen efficiently and produce excessive amounts of ROS, which can then further damage the mitochondria.
Dr. Murphy and his colleagues are conducting UMDF-funded research to develop a method for measuring in living organisms the extent to which their mitochondria have been damaged by ROS. This vicious cycle, in which already impaired mitochondria cannot use all of the oxygen presented to them further harm themselves by producing ROS, is a hallmark of mitochondrial disease’s progressive nature. Procedures developed in Dr. Murphy’s lab could ultimately be used to monitor ongoing changes in the function of mitochondria in mitochondrial disease patients and aid in assessing the effectiveness of potential therapies.

 

 

Patrick H. O’Farrell
University of California-San Francisco

2009 Research Award: $81,857

“Selecting for Transformation with Mitochondrial DNA.”
Mitochondrial diseases such as Leber’s hereditary optic neuropathy and Kearns-Sayre syndrome are caused by defects in mitochondrial DNA (mtDNA). The genetic information contained in mtDNA provides directions for the manufacture of important components of the ATP-generating machinery of the mitochondria. When this information is defective, it can significantly impair the ability of cells to convert energy obtained from food into the ATP that they need to function. Once researchers find a reliable method for inserting the correct DNA sequences into the mitochondria of mitochondrial disease patients, an important goal towards finding a cure will have been reached.
Dr. Patrick O’Farrell and colleagues at UC-San Diego are conducting UMDF-funded research to develop procedures for introducing DNA into the mitochondria of fruit flies. They will also be able to isolate flies for whom the mtDNA introduction was successful so that they can be studied. This research will produce reliable animal models for investigations of a variety of mitochondrial diseases and could also help guide attempts to repair the mitochondrial genome in humans.

 

Sarika Srivastava
Harvard Medical School

2009 Research Award: $90,804

“Investigating the Rescue of Mitochondrial Dysfunction by SIRT1 and Calorie Restriction.”
Aerobic metabolism in mitochondria is the primary source of ATP, the molecule used by cells to power the numerous activities necessary for life. Because mitochondrial disease patients have a diminished capacity to produce ATP, development of treatments to enhance energy metabolism in mitochondria would be welcome. Such treatments could also potentially forestall human aging, which is associated with declining mitochondrial function. Recent research has focused on a gene known as SIRT1, which may be an important regulator of energy balance in living systems. Factors that enhance SIRT1 activity may help to restore lost mitochondrial function associated with aging and certain diseases.
Dr. Sarika Srivastava and colleagues in the Department of Pathology at Harvard Medical School are conducting UMDF-funded research to study SIRT1 activity. Their goal is to find a way to rescue dysfunctional mitochondria in mice as well as in a cellular model for the mitochondrial disease known as MELAS. Research with these models in which SIRT1 activity is modulated will help with the development of therapies which could enhance mitochondrial energy metabolism.

 

 

Rebeca Acin-Peres, PhD
Weill Medical College, Cornell University

 

2008 Research Award: $99,990

“OXPHOS modulation by mitochondrial protein phosphorylation in mtDNA mutant cells.”
The underlying cause of many mitochondrial disease symptoms is a greatly reduced capacity for production of ATP, the energy molecule of cells. One cause of this impaired energy metabolism is the incorrect information provided by mutated mitochondrial DNA, which prevents the cellular machinery responsible for oxidative phosphorylation from functioning properly. This results in a diminished ability to produce ATP.
Dr. Rebeca Acin-Perez of Weill Medical College at Cornell University is conducting UMDF-funded research to determine how mutations in mitochondrial DNA affect the regulation of oxidative phosphorylation. Previous studies suggested that the cyclic AMP regulatory pathway, known to control many other aspects of cell function, is also involved in the regulation of mitochondrial ATP synthesis. Her research project will investigate how mitochondrial DNA mutations affect this regulatory system and contribute to mitochondrial disease. This may lead to new drug therapy strategies to boost ATP production in abnormal mitochondria.

 

 

Elizabeth Anne Amiott, PhD
Unitersity of Utah

2008 Research Award: $98,300

“Mitochondrial Fusion Defects in Neurological Disease.”
Mitochondria are dynamic organelles that can split into the small, bean-shaped structures usually depicted in biology textbooks, or fuse together to form a more elongated network. Fusion allows normal mitochondria to merge with others containing damaged DNA or proteins in order to restore normal ATP production. This is apparently an important process because certain nervous, muscular, and visual abnormalities have been linked to mutations in mitochondrial fusion genes.
Dr. Elizabeth Anne Amiott and colleagues in the Department of Biochemistry at the University of Utah are conducting UMDF-funded research to further our understanding of the role played by mitochondrial fusion in normal cell metabolism and in disease. Using yeast as a research model, she is investigating fundamental aspects of the regulation of fusion that are applicable to the development of defective nerve function in humans. This is significant because some severe neurological diseases may be helped by treatments that enhance mitochondrial fusion.

 

 

Brendan James Battersby, PhD
University of Helsinki

2008 Research Award: $150,000

“Identifying genetic modifiers of tissue-specific mitochondrial DNA segregation.”
Human cells contain many mitochondria, each with its own set of genetic information in the form of DNA. A given cell may possess both mitochondria with normal DNA and others with a mutated abnormal information set. This condition is known as heteroplasmy. Two fundamental questions arise from our understanding of heteroplasmy: Are cells able to distinguish between the two types of mitochondria that they carry? Would it be possible to encourage cells to retain the normal mitochondria while somehow reducing the number of mitochondria with mutated DNA?
Dr. Brendan Battersby and colleagues at the Research Program of Molecular Neurology of the University of Helsinki are looking for answers to these questions by conducting a UMDF-funded research project. Their goal is to identify genes in mice that control a cell’s ability to recognize mitochondria that contain abnormal DNA and thus have an impaired ability to produce ATP. If a therapy could be developed that encouraged cells to selectively retain mitochondria with normal DNA while eliminating abnormal mitochondria, it would be of great benefit to mitochondrial disease patients.

 

Bridget Elizabeth Bax, PhD
St. George’s University of London

2008 Research Award: $116,428

“Evaluation of the efficacy and safety of erythrocyte encapsulated thymidine phosphorylase therapy in two patients with mitochondrial neurogastrointestional encephalomyopathy.”
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an extremely rare inherited form of mitochondrial disease that causes severe damage to the digestive, nervous, and muscular systems. Despite its rarity, research on this disease has provided insight into the dynamics of mitochondrial DNA synthesis. This is because the disease results from the absence of an enzyme called thymidine phosphorylase and loss of this enzyme causes an imbalance of DNA building blocks in the cells. This imbalance then leads to mitochondrial dysfunction because of defective mitochondrial DNA. Also, the accumulation of excess thymidine in the blood has toxic effects on the patients.
Dr. Bridgett Bax and her colleagues at St. George’s University of London are conducting clinical research funded by the UMDF to investigate potential therapies for MNGIE. They are specifically interested in developing a form of enzyme replacement therapy for these patients. Using a novel approach called erythrocyte encapsulation they are supplying the missing enzyme to patients through use of their own treated red blood cells. This is significant because there is currently no means of ridding patients of the toxic compounds that accumulate because of the absence of thymidine phophorylase.

 

 

Deepa Vinay Dabir, PhD
University of California-Los Angeles

2008 Research Award: $100,000

“Study of redox regulated pathways in the mitochondrion.”
The manufacture of mitochondria inside of cells, called mitochondrial biogenesis, is a complex process that requires the synthesis of a large number of functional and structural proteins. While mitochondria contain their own DNA, most of the genetic directions for manufacturing these mitochondrial proteins are contained in the nucleus of the cell. After the nuclear DNA has directed the manufacture of the proteins, they must then be imported into the mitochondria through specialized transport mechanisms. Much remains unknown about how this process works.
Dr. Deepa Vinay Dabir and colleagues at the University of California-Los Angeles are studying a mutated mitochondrial import protein connected with a type of deafness. Her research with yeast is directly applicable to humans because human mitochondria use the same import protein. The importance of this research is two-fold in that it will provide fundamental insights into mitochondrial biogenesis and could also lead to the use of this pathway for introduction of therapeutic agents into mitochondria for effective treatment of mitochondrial disease. Per Dr. Dabir’s request, this grant was terminated July 2009 due to subsequently receiving a larger NIH grant that overlapped with her UMDF grant.

 

 

Leo Joseph Pallanck, PhD
University of Washington

2008 Research Award: $125,000

“The role of the PINK1/Parkin pathway in mitochondrial integrity.”
He will investigate the regulation of splitting and combining of mitochondria in cells. This is important because specific diseases are linked to defects in mitochondrial processing, especially an inability to eliminate abnormal mitochondria.

 

 

Beverly A. Rzigalinski, PhD
Virginia College of Osteopathic Medicine

2008 Research Award: $101,569

“Cerium oxide nanoparticles in the treatment of mitochondrial diseases.”
Reactive oxygen species (ROS) are normal byproducts of aerobic (oxygen-requiring) energy metabolism in the human body. Free radicals are a type of ROS that are produced in mitochondria during their synthesis of ATP, the energy used by cells for life processes. While ROS have an important role in cell signaling, they can also damage mitochondria and the cells that contain them if they are produced in excess. Anti-oxidant compounds, produced both internally and available in our diets from plant-based foods, are known as free radical scavengers. They help to deactivate free radicals before they can damage the mitochondria. While mitochondrial disease patients are often encouraged to take regular doses of anti-oxidant vitamins that are available over the counter, there is still a need for more potent therapeutic agents.
Dr. Beverly Rzigalinski and her colleagues at the Virginia College of Osteopathic Medicine are conducting UMDF-funded research on a promising new class of free radical scavengers that have a potent anti-oxidant effect. They are evaluating the beneficial effects of cerium oxide nanoparticles on mitochondrial function of cells in both tissue cultures and a fruit-fly model used to study mitochondrial disease. This research promises to develop new means of preventing the free-radical oxidative stress that is a significant cause of mitochondrial dysfunction.

 

 

Timothy E. Shutt, PhD
Yale University School of Medicine

2008 Research Award: $99,998

“Selective alteration of mitochondrial gene expression via modulation of the dual-function h-mtTFB1 and B2 factors as a potential therapy for mitochondrial diseases.”
Expression of the genetic information contained in mitochondria requires copying DNA into RNA through a process called transcription. This RNA message is then “translated” into specific proteins that mitochondria must have in order to provide ATP for the energy needs of cells. In some mitochondrial diseases, there is a connection between impaired protein translation in the mitochondria and the pathology of the disease. When these mitochondrial proteins are improperly formed, a severe energy deficit may result.
Dr. Timothy Shutt and colleagues at Yale University School of Medicine have played a major role in identifying two factors that regulate translation in mitochondria. They are currently conducting UMDF-funded research that will find ways to increasing the activity of regulatory factors that promote mitochondrial protein synthesis. This is important because it may point to new therapies for enhancing mitochondrial energy metabolism in patients with mitochondrial disease.

 

 

Stuart Smith, PhD, DSc
Children’s Hospital & Research Institute at Oakland

2008 Research Award: $128,563

“Utilization of knockout mouse models to elucidate the importance of the de novo mitochondrial fatty acid synthesis pathway in mitochondrial function.”
Fatty acids are molecules that humans obtain from food and also synthesize in their bodies. As a potential fuel source, they play a vital role in the body’s energy metabolism and provide important structural molecules used to build cell membranes. One particular fatty acid is also the precursor for the formation of lipoyl moieties that are essential for the functioning of several key mitochondrial enzymes. The details of fatty acid formation inside the fluid compartment of the cell, called the cytosol, are well established. But details of the mitochondrial pathway and its importance to mitochondrial function are poorly understood.
Dr. Stuart Smith and his colleagues at Children’s Hospital & Research Center at Oakland are conducting UMDF-funded research to develop mouse models in which functionality of the pathway is compromised. Characterization of these mice will reveal the metabolic consequences that result from defects in this pathway and will provide a framework for identifying and understanding the cause of similar defects in the human population.

 

 

Sion L. Williams, PhD
University of Miami

2008 Research Award: $99,998

“Evaluation of novel zinc finger nucleases as a means to target m.3243A>G in vivo.”
DNA is composed of four different building blocks called nucleotides which are arranged in sequence to create genes. Bacteria contain enzymes that cut DNA at specific nucleotide sequences called recognition sites. These enzymes can be used to differentiate normal and mutant genes because sometimes a mutation creates a new recognition site where the DNA can be cut. In living cells if cuts are made in mitochondrial DNA it is digested and disappears. If enzymes could be modified so that mutations in mitochondrial DNA acted as their recognition sites it would be possible to stimulate cells to digest mutant mitochondrial DNA and leave normal mitochondrial DNA untouched.
Dr. Sion Williams and his colleagues at the University of Miami are conducting UMDF-funded research into the effectiveness of modified enzymes designed to selectively cut mutant mitochondrial DNA in living cells. This is important because even small increases in the ratio of normal to mutant mitochondrial DNA in tissues like muscle can improve the wellbeing of patients with mitochondrial disease.

 

 

Paul A. Cobine, Ph.D.,
University of Utah

2007 Research Award: $99,000

“Defining copper homeostasis in the mitochondria: Recruitment and distribution of copper for the assembly of cuproenzymes.”
Mitochondrial enzymes regulate the energy-providing reactions that are necessary for normal cell function in the human body. The goal of this sequence of oxidation-reduction reactions, whereby electrons are transferred along a series of enzymes, is to produce a continuous supply of the energy molecule adenosine triphosphate (ATP).The mitochondrial enzymes that catalyze ATP synthesis are arranged in clusters known as complexes. Many of these enzymes have functional components made from elements such as iron, sulfur, or copper. Specific components of the mitochondrial enzyme complex called cytochrome c oxidase contain two copper atoms that are important in the electron transport process linked to ATP production.

Dr. Paul Cobine and colleagues at the University of Utah are investigating the mechanisms that make copper available for the manufacture of cytochrome c oxidase in cells from yeast and from humans. Little is known about the mechanisms that lead to a steady supply of copper for manufacture of new enzymes. This UMDF-funded research is significant because malfunction of cytochrome c oxidase is a common cause of mitochondrial diseases and improper copper metabolism may be a contributing factor.

 

 

Brett Graham, M.D., Ph.D.
Baylor College of Medicine

2007 Research Award: $111,779

“Mutant Complex I in Drosophila melanogaster: a Novel Genetic Model for Mitochondrial Disease.”
To derive the maximum amount of energy available from the food we eat, a series of very carefully controlled chemical reactions must occur inside the mitochondria. These cell organelles contain a variety of enzymes that are involved in transferring this food energy to adenosine triphosphate (ATP). The high-energy molecule ATP is used throughout the body to fuel the numerous energy-requiring activities necessary for life. The largest amount of ATP becomes available as a result of reactions that occur along the three enzyme complexes of the mitochondria’s respiratory chain. The first of these (complex I) is often found to be deficient in patients with mitochondrial disease.

Dr. Brett Graham and colleagues at Baylor are conducting UMDF-funded research that will lead to the development of a fruit fly model for the study of mitochondrial disease due to abnormalities of complex I. The goal is to screen for genes responsible for abnormalities related to complex I deficiency, thus pointing to potential therapies for neuromuscular disorders that result from mitochondrial malfunction. This is important because of the current lack of effective treatments for human mitochondrial disease due to complex I deficiency.

 

 

Orly Elpeleg, M.D.
Hadassah Hebrew University Medical Center, Jerusalem, Israel

2007 Research Award: $60,500

“Identification of novel genes associated with isolated complex I deficiency using whole genome mapping in small consanguineous families”
Energy in the form of ATP is made available to cells through an intricate series of chemical reactions. Mitochondria contain an important collection of enzymes that keep these reactions operating at a rapid rate. One such enzyme, Complex I, is the first in a series of enzymes referred to as the electron transport chain. It is a large molecule, with 45 subunits whose structures are specified by genes in both the nucleus and in the mitochondria themselves. Because of its complicated structure, it is not surprising that Complex I is the most common site for mutations that lead to mitochondrial disorders. (I am not sure that’s the reason, but it is indeed the most common defect) Perhaps as many as one third of mitochondrial disorders are due to some type of Complex I malfunction.

Using research funds from UMDF, Dr. Elpeleg and her colleagues at Hadassah Medical Center are employing genetic mapping techniques to analyze the entire DNA information set, the human genome, in samples obtained from a large number of patients with infantile and early childhood onset neurodegenerative disorders.  Their goal is to identify previously unknown genetic abnormalities that prevent the normal assembly of the Complex I enzyme in mitochondria. Information gained from this research will extend our understanding of how this complicated component of the electron transport chain is constructed. It could also lead to insights about the pathology of many different mitochondrial diseases that have Complex I deficiencies in common.

 

Konstantin Khrapko, Ph.D
Beth Israel Deaconess Medical Center, Boston, MA

2007 Research Award: $110,000

“Development of high throughput mtDNA sequencing for mutation detection and heteroplasmy assessment.”
Enzymes are functional molecules manufactured by cells that greatly increase the rate at which biochemical reactions occur. In mitochondria, enzyme complexes that maintain a high rate of ATP production are manufactured according to the genetic code contained in DNA. Most of this DNA is present in the nucleus, but some is actually inside the mitochondria themselves. Mitochondrial disease can result from faulty genetic directions in mutated mitochondrial DNA. But how common are these mutations in the general population and how many mutations have yet to be identified?

Dr. Khrapko and colleagues at Beth Israel Deaconess Medical Center are conducting UMDF-funded research to develop a rapid and efficient method for processing multiple mitochondrial DNA samples in order to search for mutations. High-throughput assays are powerful tools for analyzing large numbers of samples in a relatively short period of time. Sequencing the entire mitochondrial genome from a number of individuals will not only aid in screening for mutations, but will also assess the level of heteroplasmy, in which some of the mitochondria contain mutations while others are normal. This important research has the potential to develop a cost-effective means of screening for mitochondrial disorders.

 

Patrice Hamel, Ph.D.
Ohio State University

2007 Research Award: $114,189

“Molecular genetic dissection of mitochondrial complex I assembly”
All mitochondrial diseases are characterized by an impaired ability to provide the energy, in the form of ATP, that is necessary for normal life activities. It has been known for decades that a series of enzymes in the mitochondria are essential for keeping ATP available at a constant rate. These enzyme complexes, known collectively as the electron transport chain, are numbered I through IV and are located within the inner membrane region of mitochondria. Humans have this chain of respiratory enzymes in common with other oxygen-dependent organisms, and yet much of what we know about it comes from studies with organisms other than humans. Algae contain mitochondria and thus provide an easily manipulated model for the study of mitochondrial genetics.

Dr. Patrice Hamel and his colleagues at Ohio State are conducting UMDF-funded research with algae to investigate the manufacture of the key electron transport chain enzyme Complex I. This highly complicated molecule has almost four dozen subunits and is the most common site for mutations that lead to mitochondrial disorders in humans. In many cases the genetic defects causing improper assembly of Complex I in human mitochondria have not been identified and thus Dr. Hamel’s research with algae will help to identify many of these. This could then lead to a clearer understanding of the underlying genetic abnormalities that result in human mitochondrial disease.

 

Michael Paul King, Ph.D.
Thomas Jefferson University, Philadelphia, PA

2007 Research Award: $118,648

“Development of high throughput assays for mitochondrial respiratory chain function.”
Mitochondrial disorders can result in a wide variety of illnesses that differ greatly in terms of symptoms, severity, and age of onset. Yet, they all share the feature of a diminished capacity for cells to produce the energy molecule ATP under aerobic (oxygen-requiring) conditions. This process, called cellular respiration, occurs in mitochondria and is the major means through which the chemical energy in food is made available to the cells for all of the activities necessary for life. One strategy for developing an effective treatment for mitochondrial disease would entail discovering ways to enhance respiratory chain ATP synthesis.

Dr. King and his colleagues at Thomas Jefferson University are using UMDF-provided research funds to develop a rapid screening method that searches for chemicals that can improve mitochondrial respiratory chain function in treated cells. High-throughput assays are powerful tools for analyzing large numbers of samples in a relatively short period of time. Use of this technology will allow numerous different compounds with potential therapeutic properties to be evaluated. This is important because it is difficult to conduct studies assessing drug treatment effectiveness directly in mitochondrial disease patients, who differ significantly both in terms of symptoms and responsiveness to therapies. The automated assay method employed by Dr. King will allow for preliminary evaluation of drugs in a standardized fashion and hopefully identify drugs which could subsequently be tested on patients.

 

Paolo Pinton, Ph.D.
University of Ferrara, Italy

2007 Research Award: $86,250

“Mitochondrial calcium signaling and organelle dysfunction in mitochondrial diseases: molecular determinants and regulatory mechanisms.”
An important topic in the study of cell biology has to do with how cells respond to a changing environment in order to keep constant certain factors necessary for their survival. At the same time, the life spans of individual cells are determined by genes that will ultimately cause apoptosis (programmed cell death). Of course, cells can also die prematurely because of disease. Biologists are interested in how these different aspects of a cell’s existence are regulated. A key insight comes from the role that ionic calcium plays as a signal to activate specific processes within the cell. It is also known that build-up of calcium within mitochondria precedes the changes that result in cell death by apoptosis and also premature death due to damage by certain toxins.

Dr. Paolo Pinton and colleagues at the University of Ferrara are conducting UMDF-funded research to investigate calcium balance in mitochondria. This important fundamental research project will increase our understanding of how calcium functions as a mitochondrial regulatory molecule. Because changes in calcium concentration have been linked to certain mitochondrial diseases, it will also help to identify cellular disease mechanisms associated with mitochondrial disorders.

 

 

Mingdong Ren, Ph.D.
New York University School of Medicine

2007 Research Award: $157,450

“Genotype-Phenotype Correlation and Genetic Modifiers in Barth Syndrome.” Barth syndrome is a rare genetic disorder that causes generalized muscle weakness, affecting both the muscles of the heart and of the musculoskeletal system. The disease also prevents normal function of a specific population of immune system cells and has a high rate of infant mortality. The effects of Barth syndrome on various organs in the human body are due to impaired mitochondria, the energy-providing organelles found in most cells. Muscles and other tissues depend upon the ready availability of mitochondrial ATP in order to function normally. Barth’s patients are thus at a significant disadvantage because they cannot convert adequate amounts of energy from their food into ATP for use by their cells. Because there are only a few patients available for research at any time, it is necessary to use animal models for detailed study of this disease.

In a UMDF-funded project, Dr. Ren and colleagues at New York University are using fruit flies as a research model for the study of Barth syndrome. Discovery in these insects of genetic modifiers that affect the syndrome’s development will shed light on its pathology and could also point to potential therapies for other mitochondrial disorders.

 

Ann Saada, Ph.D.
Hadassah Hebrew University Medical Center

2007 Research Award: $98,340

“Mitochondrial DNA synthesis and Krebs (tricarboxylic acid) cycle: the succinyl-CoA synthase.”
By now, many people are aware that their DNA contains the genetic information required for the cells in their body to function normally. DNA is actually a code that spells out the structure of a cell’s proteins and most of this information is housed inside the cell’s nucleus. An additional level of complexity was added to the understanding of mitochondrial function when it was discovered that mitochondria also contain DNA. Mitochondria are the primary source of ATP, the high-energy molecule used by cells to carry out a variety of activities. How this organelle is produced in the cell when the genetic instructions for its manufacture are located in two separate cell compartments makes for a complex story. It was recently discovered that mitochondrial disease in some infants is actually due to mitochondrial DNA (mtDNA) depletion, progressive loss of the DNA normally present in their mitochondria. The effects of this depletion are widespread, impairing the function of multiple organs such as the brain, liver, and heart.

Dr. Saada and her colleagues at Hadassah – Hebrew University Medical Center are conducting UMDF-funded research using cells derived from patients with mtDNA depletion. Previous research linked a type of brain mitochondrial disease with mtDNA depletion due to a specific genetic mutation. Her goal is to understand the pathophysiology of this process and to move towards identifying methods for reversing it.

 

Ludivine Walter, Ph.D.
Cornell University, NY

2007 Research Award: $100,000

“Determination of the nuclear transcriptional responses that affect animal physiopathology upon impaired mitochondrial respiratory chain function.”
For over forty years, biological researchers have used the roundworm Caenorhabditis elegans as a model for understanding the genetic control of development. Its size (a little more than a millimeter in length) and rapid growth (less than four days to reach maturity) makes it an ideal organism for laboratory investigations in the fields of genetics, molecular biology, and neurobiology. Like humans, C. elegans relies upon mitochondria to supply most of its ATP for energy-requiring processes. Also similar to humans, specific mutations in this roundworm’s DNA have been linked with mitochondrial disorders.

Dr. Walter and her colleagues in the Department of Molecular Biology and Genetics at Cornell are conducting UMDF-funded research that is breaking new ground in characterizing how changes in gene expression in C. elegans result in abnormal mitochondrial energy metabolism. As with humans, impaired mitochondrial function can result in a diverse array of functional outcomes and disabilities. It is thus expected that this project will uncover underlying processes that are also at work in human mitochondrial disease.

 

Tina Wenz, Ph.D.
University of Miami

2007 Research Award: $94,481

“Increased mitochondrial biogenesis as therapy to mitochondrial myopathies.”
A large percentage of the energy that we derive from the food we eat is used up by our skeletal muscles. These organs have a high metabolic rate that requires a constant supply of ATP, the energy currency that we spend for the many activities necessary for life. Most of this ATP is made available by aerobic (oxygen-requiring) metabolism in mitochondria, which are present in large numbers in the muscles of normal individuals. It is not surprising, then, that patients with various mitochondrial disorders often experience severe muscle weakness and also fatigue easily. What can be done to increase the number of normal mitochondria in patients whose muscles are so starved for energy?

In a UMDF-funded project, Dr. Wenz and colleagues at the University of Miami are determining whether mice with a defective mitochondrial enzyme will improve when they are provided with a gene that increases the number of mitochondria in their muscle cells. These mice, which were developed in her lab, have a progressive disorder leading to greatly impaired muscle function. Investigations with this animal model will hopefully point towards an effective therapy. This is important because of the current scarcity of treatments for mitochondrial disease in humans.

 

 

Brian H. Robinson, PhD
Hospital for Sick Children, Canada

2006 Research Award: $125,000

“High throughput screening for mitochondrial enhancers”
The human brain constantly requires an amount of energy that is far out of proportion to its size. Any factor that decreases energy metabolism in the brain, such as impairment of the mitochondria’s capacity to produce ATP, would have severe consequences both on brain development and function. Drug treatment of neurological disorders is always a challenge because of the blood-brain barrier, the purpose of which is to protect the neurons, brain functional cells, from potential toxins in the blood. The problem with developing effective treatments for brain disorders is that many drugs which might prove effective are denied access into neurons by this barrier. Development of a drug that would stimulate mitochondria to produce ATP at a maximum rate and could also successfully cross into the brain to reach neurons possessing impaired mitochondria is an ongoing challenge.

Dr. Brian Robinson and his colleagues at the Metabolism Research Programme of the Hospital for Sick Children in Toronto are conducting UMDF-funded research to identify chemicals that can cross the blood-brain barrier for their ability to increase ATP production by mitochondria. They are using a cell-based assay allowing rapid screening of a large number of drugs that might enhance the synthesis of mitochondrial respiratory enzymes. This is important because the class of compounds being studied could readily cross into the brain to potentially treat serious neurological diseases in children.

 

Thomas W. O’Brien, PhD
University of Florida

2006 Research Award: $125,000

“Mitochondrial ribosomal proteins: candidate genes for mitochondrial disease”
A cell’s DNA is important because of the information it carries. This genetic code contains the directions for manufacturing proteins in the cell. The sequence of events that leads to the formation of these proteins begins with transcribing the DNA into messenger RNA (mRNA). Important organelles called ribosomes direct the subsequent translation of the mRNA code into proteins. If mitochondria are going to provide adequate amounts of energy, then their own ribosomes must function correctly to direct the continued replacement of ATP-producing enzymes. While evidence suggests that incorrectly formed ribosomes may lead to certain mitochondrial diseases, little is known about their components and how these ribosomal proteins contribute to the overall process of translating mRNA into enzymes required by the mitochondria.

Dr. Thomas O’Brien and colleagues at the University of Florida are conducting UMDF-funded research to further our understanding of the functional significance of a number of ribosomal proteins in mitochondria. This research is important because their lab is especially interested in identifying proteins associated with specific mitochondrial diseases.

 

Håkan Westerblad, MD, PhD
Karolinska Institute, Sweden

2006 Research Award: $122,720

“Mechanisms of muscle dysfunction studied in mouse models of mitochondrial myopathies”
It is well known that cells require the organelles called mitochondria to function normally so as to maintain a constant supply of energy. When a patient’s mitochondria are defective, organs needing large amounts of energy, such as skeletal muscle, are especially affected. Because both the maintenance of healthy muscles and the regulation of their contraction are so complex, the relationships between mitochondrial disease and muscle pathology are also likely to be complex. Obtaining a detailed picture of these disease mechanisms in humans is very difficult. What is needed is a means of linking specific mitochondrial defects with specific areas of muscle dysfunction in isolated muscles obtained from individuals with known mitochondrial defects.

Dr. Håkan Westerblad and colleagues at the Department of Physiology and Pharmacology of the Karolinska Institute have developed animal models that allow them to answer such questions. Conducting UMDF-funded research, they are comparing various aspects of function in muscle from normal mice and from mice with different types of mitochondrial defects. They are investigating regulation of muscle contraction, force generation by muscles, and factors that can lead to the death of individual muscle cells. The importance of this research lies in the detailed information that will be gained about exactly how abnormal mitochondria cause muscle dysfunction. Once information concerning specific disease mechanisms has been acquired, it should provide insight into promising treatment strategies.

 

Haya Lorberboum-Galski, PhD
Hebrew University of Jerusalem

2006 Research Award: $115,000

“Enzymereplacement therapy: A novel approach for treating a mitochondrial disease-LAD deficiency”
The many different medical conditions that are placed under the category “mitochondrial disease” have in common the disruption of one or more components of the energy “machinery” of the mitochondria. This machinery is made up of a number of enzymes that are crucial to the production of the energy molecule ATP. If even one of these enzymes is defective or absent, then ATP production may be greatly reduced, with serious consequences for organs such as the brain and skeletal muscle that depend upon large amounts of ATP for normal development and activity. Lipoamide dehydrogenase (LAD) is an important component of three enzyme complexes in mitochondria and LAD deficiency is an inherited disease that disrupts normal mitochondrial function.

Dr. Lorberboum-Galski and colleagues at the Department of Cellular Biochemistry and Human Genetics at Hebrew University are conducting UMDF-funded research to investigate the possibility that enzyme replacement therapy can be used to treat LAD deficiency. They are developing methods for placing the normally functioning enzyme into cultured cells of mitochondrial disease patients and also into the mitochondria of laboratory mice that are afflicted with the disease. This is a promising approach because there are currently no cures for mitochondrial disease and such research could lead to therapies that would correct its fundamental causes.

 

Zaza Khuchua, PhD
Vanderbilt University Medical Center, Tennessee

2006 Research Award: $110,000

“Animal models of human Barth syndrome, a mitochondrial cardiolipin disorder”
Barth syndrome is a rare genetic disorder that causes generalized muscle weakness, affecting both the muscles of the heart and of the musculoskeletal system. The disease prevents normal function of a specific population of immune system cells and has a high rate of infant mortality. The similarity of effects that the disease has on very different organs in the human body can be explained by how it affects mitochondria, energy-providing organelles found in most cells. Previous studies have shown that the muscle mitochondria in Barth patients are deficient in cardiolipin, a compound that is an essential component of the mitochondrial inner membrane. Production of the energy needed for cell activity is impaired in the absence of normal cardiolipin levels.

Dr. Zaza Khuchua and colleagues at Vanderbilt University Medical Center have developed promising animal models of human Barth syndrome. Using research funds provided by the United Mitochondrial Disease foundation, they will study a previously developed fish model of Barth syndrome and will complete development of a mouse model of the same disease. These are significant developments because the use of animal models will allow extensive research on the syndrome’s basic pathology without having to rely upon human subjects.

 

Stephane Chiron, PhD
University of California-San Diego

2006 Research Award: $98,500

“Utilization of fission yeast as a model for mitochondrial morphology: a new approach to discover novel genes involved in animal cells”
The cells that make up the human body are packed with organelles, complex machinery responsible for virtually all life processes. These functional components are dynamic and mobile, not the static structures often suggested by pictures in biology textbooks. Mitochondria are essential organelles responsible for maintaining normal energy levels in cells and previous research has shown that specific transport systems are dedicated to moving them within the cell interior. Other research has suggested that abnormal movement and shaping of mitochondria are associated with certain muscle and nervous system diseases in humans. Detailed studies of the internal systems responsible for distributing and positioning mitochondria within cells could shed light on disease mechanisms common to some mitochondrial diseases.

Dr. Stephane Chiron and colleagues at U.C.-San Diego are conducting UMDF-funded research seeking to further understand how mitochondrial movement is regulated. They are using a species of yeast that has the same microtubule transport system for movement of mitochondria as is found in human cells. Such yeast cells are easily cultured and maintained in the lab and, because of their similarities with human cells, will yield data that is applicable to human mitochondrial disease.

 

Michael J. Palladino, PhD
University of Pittsburgh

2006 Research Award: $98,457

“Developing therapies for mitochondrial disease”
Mitochondrial diseases are relatively rare and a single clinician may encounter only a small number of such patients over a long period of time. Developing a profile of the “typical” patient is challenging also because any two individuals with the same disorder may follow different courses and experience signs and symptoms that differ in both type and severity. It is therefore difficult to collect a large number of similar mitochondrial disease patients for clinical research in order to assess the effectiveness of promising treatments. Fruit flies have many genetic features in common with humans and have been used for decades to uncover aspects of human disease. Using modern biotechnology to produce fruit flies with specific genetic anomalies that lead to mitochondrial disease would be very helpful in identifying underlying disease mechanisms.

Dr. Michael Palladino and his colleagues at the University of Pittsburgh are using fruit flies with mutated mitochondria to measure the effectiveness of treatments for diseases that cause progressive deterioration of the nervous and muscular systems. The mitochondrial dysfunction in these animals causes movement disorders and decreases their life spans. The importance of this UMDF-funded research is that it will allow wide-spread screening to determine the efficacy of specific drug therapies in genetically similar populations with mitochondrial disease.

 

Doron Rapaport, PhD
University of Tuebingen, Germany

2006 Research Award: $98,000

“Defective biogenesis of mitochondrial beta-barrel proteins as a cause for Mohr-Tranebjaerg syndrome”
Mitochondria are complex cell organelles whose manufacture is directed by the DNA code contained in genes of both the nucleus and of the mitochondria themselves. Because the majority of mitochondrial components are encoded for in nuclear DNA, their assembly involves the transport of proteins from the interior of the cell into the mitochondria. Anything that interrupts this complicated sequence of events has the potential to impair mitochondrial function, leading to impaired mitochondrial energy metabolism. The consequences of such impairment can be seen in Mohr-Tranebjaerg syndrome (MTS), a disorder of the nervous system that results in the development of deafness, blindness, mental retardation and dysfunctional movement.

Doron Rapaport and his colleagues at the University of Tuebingen are conducting UMDF-funded research to investigate the link between a mutation associated with MTS and the insertion of nuclear-encoded proteins into the mitochondrial membrane. This research is important because it will provide insights into the normal assembly of mitochondria, as well as into the pathology of a complex mitochondrial disease.

 

Vishal Gohil, PhD
Massachusetts General Hospital

2006 Research Award: $88,850

“Molecular signatures of mitochondrial disorders”
It should not be surprising to learn that our muscles use up a large percentage of the energy we derive from our food. Muscle cells have such a high metabolic rate that that they burn a significant number of calories even when we are asleep. It is the job of mitochondria in these muscle cells to make energy available in the form of ATP on a reliable basis. ATP is the currency that is “spent” for energy-requiring activities in the human body and therefore mitochondria are present in large numbers in normal muscle cells. Conversely, when patients have widespread energy dysfunction associated with abnormal mitochondria, the muscles are especially vulnerable.

Dr. Vishal Gohil and colleagues at the MGH Center for Human Genetic Research are conducting UMDF-funded research to investigate the effects of malfunctioning mitochondria on mammalian muscle function. They are developing research models for about a dozen different human mitochondrial diseases by interfering with the expression of DNA in a mouse muscle cell line. This approach is important because it will allow comprehensive laboratory study of a number of mitochondrial diseases and their associated defects. Their findings should provide insight into appropriate treatments for mitochondrial disease in humans.

 

John Gordon Lindsay, PhD
University of Glasgow, Scotland

2006 Research Award: $43,494

“Enzymatic, assembly and genetic studies on the human pyruvate dehydrogenase multi-enzyme complex”
The machinery inside living cells is very complex and includes a variety of enzymes that regulate the rates at which chemical reactions occur. The reactions that take place within mitochondria are especially important because they are crucial to maintaining normal levels of the energy molecule ATP. The process whereby the chemical energy in glucose is ultimately transferred to ATP begins in the cytosol outside of the mitochondria and results in the formation of an intermediate molecule called pyruvate. While a relatively small amount of ATP becomes available during the breakdown of a glucose molecule into two pyruvates, obtaining the maximum amount of energy available from glucose requires that the pyruvates enter the mitochondria for further processing. Once inside, the pyruvate molecules undergo a chemical reaction that is catalyzed by pyruvate dehydrogenase complex (PDC), an important mitochondrial enzyme.

Dr. Lindsay and his colleagues at the Institute of Biomedical and Life Sciences of the University of Glasgow are conducting UMDF-funded research using modified bacteria that contain mutated forms of PDC in order to determine how changes in the complex’s function can result in mitochondrial disease. If the enzyme is defective, then numerous other reactions that follow the one catalyzed by PDC will not occur and mitochondrial production of ATP will be impaired. This research is important because PDC mutations are suspected in a large number of metabolic disorders in humans.

 

Patrick F. Chinnery, PhD
University of Newcaslte upon Tyne, UK

2005 Research Award: $162,878

“The Population prevalence of ten mtDNA mutations”
Each of us depends upon our own mitochondria to derive energy, in the form of ATP, from the food that we eat. Because ATP has to be readily available for use by our cells the mitochondrial enzyme systems responsible for its production are constantly working. Unfortunately, this complicated machinery can malfunction, sometimes because the mitochondrial enzyme complexes were improperly assembled. What specifically goes wrong with the mitochondria to cause this in patients with mitochondrial disease? We know that the enzyme complexes in the mitochondria are manufactured by following the directions contained in the genetic code in the form of DNA. Most of this DNA is present in the nucleus, but some is actually inside the mitochondria themselves. One possible cause of mitochondrial malfunction is that the mitochondrial DNA (mtDNA) contains a mutated faulty genetic code. But how common are these mutations in the general population?

Professor Patrick F. Chinnery and his team at the University of Newcastle Upon Tyne in the U.K., are conducting UMDF-funded research to determine the prevalence of mutations in mtDNA in the general population. They are comparing these findings with the number of mutations identified in mitochondria from individuals living in the same region who are affected with mitochondrial disease. It is suspected that mtDNA mutations are more common than is currently understood. Dr. Chinnery’s study will lay the groundwork for developing a more accurate assessment on their incidence in the population at large.

 

Michael Frohman, MD PhD
Stony Brook University, New York

2005 Research Award: $141,027

“MitoPLD, a novel enzymatic regulator of mitochondrial morphology and fusion”
Mitochondria are complicated structures that, in some ways, are like miniature cells within a cell. Unlike any other cell organelles, mitochondria contain their own DNA, which is used, along with DNA in the nucleus, to direct the manufacture and maintenance of their own enzyme systems. It is the mitochondrial enzymes that oversee a complex set of reactions which transfer energy from the food we eat to the widely used energy molecule known as ATP. Although they are typically depicted in biology textbooks as kidney-bean shaped structures, mitochondria can merge or fuse with each other to form much longer, complex organelles. Previous studies have shown that conditions which favor mitochondrial fusion are necessary for them to carry out energy metabolism at normal levels. Factors that block fusion of mitochondria lead to fragmentation of the organelles and impair their activity. Fusion apparently helps to keep some defective mitochondria functional by providing the correct DNA genetic code for enzyme synthesis.

Dr. Michael Frohman and his team at Stony Brook University in New York are conducting UMDF-funded research that will add to our understanding of why the fusion of mitochondria is so crucial to their normal operation. They have discovered a new gene, called MitoPLD, which regulates mitochondrial fusion and are determining how the gene works. This is important because defective fusion of mitochondria is linked to specific mitochondrial diseases of the nervous system, and perhaps as well as those of other body systems.

 

Elena Rugarli, MD
Telethon Institute of Genetics and Medicine, Italy

2005 Research Award: $126,500 

“The Mechanism of Mitochondrial Dysfunction in Paraplegin-Deficient Mice.”
It has long been recognized that the body’s cells are dependent on mitochondria for reactions that provide much of the energy they need to survive. Mitochondria are extremely complex organelles with numerous interacting components. Paramount among these are the enzymes that keep the energy-producing reactions flowing quickly and efficiently. Just as with the parts of a human-made machine, improperly manufactured proteins can negatively impact energy production by mitochondria.

Dr. Elena Rugarli and her team at National Neurological Institute in Milan, Italy, are conducting a UMDF-funded study of an enzyme (paraplegin) that normally removes defective mitochondrial proteins before they can hamper energy metabolism. She is using paraplegin-deficient mice as a model to investigate the human condition known as hereditary spastic paraplegia, characterizing the role that abnormal mitochondrial protein synthesis plays in this neurodegenerative disease. Gaining an understanding of the normal functions of paraplegin in mitochondria and the specific consequences of its loss is a necessary step towards developing effective treatments for this incurable disease.

 

Mair Churchill, PhD
University of Colorado Health Sciences Center

2005 Research Award: $116,133

“Molecular Basis of Mitochondrial Gene Regulation”
Many of us have an understanding of the significance of the genetic code and how it contains the directions, in the form of DNA, for making the cells of the human body. The DNA code is “transcribed” into a related molecule known as messenger RNA, which is then “translated” into the proteins that make up the organelles. These organelles are the functional units of the cell and their amino acid structures can ultimately be traced back to the DNA genetic code. If you’ve looked through a microscope in a biology course to see the nucleus of a cell, you may have been told that this is where the DNA resides. It is true that the instructions for manufacturing the cell’s organelles are to be found in the nucleus. There is one organelle, however, for which this is only partially correct. Mitochondria, the primary sites of energy metabolism in the cells, actually contain some of the DNA that is necessary for their own formation. The process whereby the DNA stored in both the nucleus and the mitochondria are used to make mitochondrial proteins is extremely complex.

 

Dr. Mair Churchill and her team at the University of Colorado Health Sciences Center are conducting UMDF-funded research to better understand the transcription of mitochondrial DNA (mtDNA) into messenger RNA. This process of always “rewriting” the DNA code into an RNA code before it is used to makes proteins assures that the original message remains unchanged. Transcription is a complicated procedure that is under the control of specific regulatory molecules known as transcription factors. The mitochondria have their own set of these to assure that mtDNA is properly transcribed into messenger RNA. Dr. Mair is using X-ray crystallography methods to determine the exact molecular structures of these mitochondrial transcription factors. Being able to accurately describe their structure will provide insight into how they operate. This will, in turn, also improve our understanding of mitochondrial diseases that are caused by abnormal transcription factor activity.

 

Linda Spremulli, PhD
University of North Carolina, Chapel Hill

2005 Research Award: $110,980 

“Biochemical and structural studies on mitochondrial disease mutations in methionyl-tRNA.”
By now, many people are aware that their DNA contains the genetic information needed for the cells in their body to function normally. The DNA is actually a code that spells out the structure of the cells’ proteins and most of it is housed inside the nucleus. Mitochondria are the primary source of ATP, the high-energy molecule used by cells to carry out a variety of activities. An additional level of complexity was added to the understanding of mitochondrial function when it was discovered that mitochondria also contain DNA. How this organelle is produced when the genetic instructions for its manufacture are located in two separate cell compartments makes for a complex story. The DNA code is “transcribed” into a related molecule known as messenger RNA, which is then “translated” into the proteins that make up the organelles. Translation involves the delivery of specific amino acids to the messenger RNA template so that the correct protein can be manufactured. It is the job of the transfer RNAs (tRNA) to deliver the amino acids as they are required. Because mitochondrial tRNA is made from the genes in mitochondrial DNA, mutations in those genes can be inherited. Such inherited mutations can result in debilitating, and sometimes fatal mitochondrial disease.

Dr. Linda Spremulli and her team at the University of North Carolina, Chapel Hill, will investigate mutations that cause “mis-folding” of a mitochondrial transfer RNA that is linked to specific defects in the function of mitochondria. If a specific tRNA is unable to function properly, then protein synthesis will be compromised. This research will provide fundamental insights into how a malfunctioning transfer RNA originating inside mitochondria can cause deficits in mitochondrial energy production.

 

Richard H. Haas, MB, BChir
University of California, San Diego

2005 Research Award: $109,991

“Diagnostic Utility of DHPLC in Mitochondrial Disease”
Some mitochondrial disease patients suffer through numerous misdiagnoses before finally learning of the true cause of their illness. This is not surprising since fatigue, muscle-weakness, gastrointestinal upset and other symptoms resulting from impaired mitochondrial function could also result from a number of other diseases. While a reduced ability to provide a constant flow of energy to the cells in the form of ATP is the common underlying pathology of mitochondrial illnesses, this basic defect can manifest itself in a variety of ways. Since effective medical practice involves achieving an accurate differential diagnosis, being able to either identify or rule out mitochondrial disease through a simple, straightforward test would be immensely helpful.

Dr. Richard H. Haas and his team at the University of California, San Diego, are conducting UMDF-funded research that will evaluate the potential of one such test. They are using blood and saliva samples from patients to develop simple, more reliable methods for detecting mitochondrial DNA mutations that can lead to disease. The long-term goal of this research is to develop standard procedures for rapid screening and diagnosis of mitochondrial disease.

 

Luca Scorrano, MD, PhD
Dulbecco-Telethon Institute, Italy

2005 Research Award: $94,000 

“Role of mitofusin-2, a mitochondria-shaping protein mutated in Charcot-Marie-Tooth IIa, in controlling mitochondrial function and apoptosis.”
A typical cell contains eight or so different kinds of organelles with specific functions that contribute to its growth and maintenance. Mitochondria are the organelles responsible for providing energy for the many things that a cell must do to survive. They must be present in sufficient quantities at all times and can be synthesized inside the cell as needed. Instead of being made from scratch, new mitochondria develop from pre-existing ones, with constant replenishing of the necessary proteins as directed by DNA in both the nuclei and in the mitochondria themselves. Interestingly, at any point in time variable numbers of mitochondria may fuse together to form elongated structures, or longer structures may fragment into the smaller bean-shaped structures often depicted in biology textbooks. Previous studies have demonstrated that the ability to fuse is important to maintaining normal mitochondrial function and that fusion is a highly regulated activity.

Dr. Luca Scorrano and his research team at the Venetian Institute of Molecular Medicine in Italy are studying abnormalities in mitochondrial shape and function that result from a mutated fusion-regulator called mitofusin 2. This protein is important in the maintenance of mitochondrial shape and a defect in it is associated with Charcot-Marie-Tooth IIa disorder, a type of muscular dystrophy. The importance of this research lies in the insights that will be gained into the role of mitofusin 2 in maintaining normal mitochondria and how disease results from its mutated form.

 

Jan-Willem Taanman, PhD
University College London, UK

2005 Research Award: $86,455 

“The assembly pathway of human cytochrome-c oxidase studied with RNA interference”
Adenosine triphosphate (ATP) is the energy source used by the human body for all of its life processes. It took several decades during the first half of the 20th century to figure out how the potential energy in food is carefully transformed to ATP for the use of individual cells. Part of the challenge had to do with understanding the complexities of the mitochondrial enzymes and the contributions that each makes to the overall energy-transformation process. The cytochromes, vital components of this mitochondrial respiratory enzyme system, were first identified in the 1920’s but how they are manufactured inside the mitochondria has still not been fully worked out.

Dr. Jan-Willem Taanman and his team at the University College of London, U.K. are conducting UMDF-funded research to characterize in greater detail the assembly pathway of cytochrome-c oxidase, an important enzyme involved in mitochondrial ATP synthesis. This research will lead to detailed fundamental information concerning how a crucial mitochondrial enzyme is assembled and provide insight into mitochondrial diseases that result from its malfunction.

 

Tal Mia Lewin, PhD
University of North Carolina, Chapel Hill

2005 Research Award: $70,525

“Barth Syndrome: A Mitochondrial Disease with Insights into Cardiolipin Synthesis”
Barth syndrome is a rare genetic disorder that causes generalized muscle weakness, affecting both the muscle of the heart and of the musculoskeletal system. It is a severe disease that also has a negative impact on a specific population of immune system cells. Previous studies have shown that the muscle mitochondria in Barth patients are deficient in cardiolipin, a compound that is an essential component of the mitochondrial inner membrane. Production of the ATP needed for cell activity is compromised in the absence of normal cardiolipin levels.

Dr. Tal Mia Lewin and her team at the University of North Carolina, Chapel Hill are conducting UMDF-funded research to investigate the role played by a defective enzyme in Barth syndrome that normally regulates the synthesis of cardiolipin. They are using cell cultures to identify the detailed steps leading to the manufacture of this important molecule. Investigating the fundamental pathology of this fatal mitochondrial disease can set the stage for development of effective treatments. Although Barth’s is a rare disease, this research should provide insight into the disease mechanisms of other mitochondrial disorders as well.

 

David C. Chan, MD, PhD
California Institute of Technology

2004 Research Award: $128,000

“Understanding the role of mitochondrial fusion in mitochondrial myopathies”
Dr. Chan’s lab will investigate the formation of cell organelles called mitochondria that are responsible for energy production in human cells. Human cells contain several kinds of organelles, each of which has specific jobs. Mitochondria are especially complex machines made from a variety of proteins. The genetic code for the manufacture of most of these proteins resides in the DNA of the cell’s nucleus. Mitochondria are unique among organelles, however, because the nucleus does not contain all of the genetic information needed to make them. Some of this information resides in the mitochondria’s own DNA.

Dr. Chan’s lab will breed lab mice that have undergone tissue-specific deactivation of factors needed for mitochondrial fusion and will study the effects that this has on skeletal and cardiac myopathies. Instead of being made from scratch, new mitochondria always develop from pre-existing ones, with constant replenishing of the necessary proteins as directed by both the nuclear DNA and mitochondrial DNA. Interestingly, at any point in time variable numbers of mitochondria may fuse together to form elongated structures, or longer structures may fragment into the smaller bean-shaped structures often depicted in biology textbooks. The rate at which these events, division and fusion, occur is under the control of a specific group of enzymes called GTPases that reside in mitochondria. Some mitochondrial diseases are caused by defective mtDNA and fusion may actually protect the mitochondria from following the incorrect code of defective mtDNA.

Dr. Chan plans to investigate the role of three GTPases required for the fusion of mammalian mitochondria. Previous research has shown that mouse embryos lacking these will die early in their development. He will produce lab mice that have undergone deactivation of the GTPases needed for mitochondrial fusion, but only in their skeletal muscle and heart muscle. Because human mitochondrial diseases often affect function of these two types of muscle, this research will provide insight into the role that fusion of mitochondria plays in progression of the disease.

 

Miriam H. Meisler, PhD
University of Michigan

2004 Research Award: $108,305

“The nuclear-encoded gene OMI and mitochondrial disease”
Dr. Meisler has been conducting research with mice that possess a mutation causing abnormal mitochondrial function. Cells contain several kinds of machines called organelles, each of which has specific functions. The organelles under study in Dr. Meisler’s lab are the mitochondria, especially complex cell organelles that are responsible for energy production. The mutated mouse gene is called OMI and it causes the affected mice to develop a neuromuscular disease that results in severely uncoordinated movement and wasting of muscles. There are a number of diseases that cause degeneration of the nervous system and the muscles that it controls. The changes experienced by the mice with the mutated OMI gene are a direct result of the inability of their abnormal mitochondria to provide adequate energy.

Building upon her experience with this mouse disease model, Dr. Meisler has designed a study in which she will screen 300 patients with inherited mitochondrial disease for OMI mutations similar to those found in mice. Mutated DNA sequences that occur in the mitochondrial disease patients, but not in healthy controls, will be tested for their involvement in the development of mouse neurodegenerative disease. This will be accomplished by microinjection of the candidate DNA sequences into fertilized eggs that would normally develop into mice with the fatal disease.

 

Volkmar Weissig,
Northeastern University, Dept. of Pharmaceutical Sciences

2004 Research Award: $99,360

“Development of a method for transforming mitochondria in living mammalian cells with exogenous DNA”
Dr. Weissig’s research group is interested in developing a means of replacing defective DNA sequences in mitochondria with the correct sequences that are required for normal function. Mitochondria are complex energy-producing cell organelles that are made from a variety of proteins. The genetic code for the manufacture of most of these proteins resides in the DNA of the cell’s nucleus. Mitochondria are unique among organelles in that the nucleus does not contain all of the genetic information needed to make them. Some of this information resides in the mitochondria’s own DNA. If a defect is present in the mitochondrial DNA (mtDNA), then it will keep the mitochondria from making the normal proteins needed for energy production. Many mitochondrial diseases due to mtDNA defects develop into serious, ultimately fatal neuromuscular disorders. Gene therapy as an approach to treatment of these diseases holds great promise.

Dr. Weissig plans to develop and perfect a mechanism for transporting normal DNA through the interior of cells to the mitochondria, with subsequent mitochondrial uptake of the DNA. Researchers are also developing gene therapy approaches to the treatment of diseases such as muscular dystrophy. This is more straightforward than treatment of mitochondrial disease because it is easier to insert the correct DNA sequence into the nucleus of cell. Extra challenges are associated with inserting the correct DNA sequence into mitochondria. Development of a reliable method for insertion of DNA into mitochondria would be a significant step in treatment of often fatal mitochondrial diseases.

 

Vamsi K. Mootha
Broad Institute, Massachusetts Institute of Technology

2004 Research Award: $90,200

“Genomic Approaches to Human Cytochrome c Oxidase Deficiency”
Dr. Mootha’s research team will identify genes that code for factors responsible for directing the synthesis of an important component of the mitochondrion. Mitochondria are energy-producing organelles contained in most human cells. They possess a series of molecules that are called collectively the respiratory chain. The respiratory chain is the cellular site where most of the energy is derived from foods that we eat to synthesize the energy-rich molecule ATP. The complex known as “cytochrome c oxidase” is an important component of the respiratory chain. Various assembly factors are required to direct the manufacture of new cytochrome oxidase complexes in the mitochondria.

Researchers have identified five human assembly factor mutations that can lead to abnormally functioning cytochrome c oxidase and diminished production of ATP by the mitochondria. Dr. Mootha has recognized the need for a comprehensive inventory of the nuclear encoded genes that are required for proper cytochrome c oxidase assembly and function. Computer analysis of data made available by the Human Genome Project can be used to perform a search for all human DNA containing the genetic code for cytochrome c oxidase assembly factors. Once specific DNA sequences have been identified as potential candidates, the research team will validate these sequences through the use of RNA interference in cultured cells. This procedure prevents the cells from expressing that particular DNA sequence. Subsequent biochemical assays of these cells will measure any changes in mitochondrial function that resulted from blocking expression of the DNA. Information gained from this research will increase our understanding of normal mitochondria function, providing insights into what goes awry when mitochondrial disease develops.

 

Joseph A. Garcia, MD, PhD
University of Texas SW Medical Center at Dallas

2004 Research Award: $88,852

“The hypoxia sensing transcription factor EPAS1/HIF-2a is a novel mitochondrial disease candidate in mice and man”
Dr. Garcia’s lab will screen cells obtained from children with mitochondrial disease for the presence of an abnormal protein that has lost the ability to stimulate the production of anti-oxidant enzymes. Mitochondria are energy-producing organelles contained in most human cells. They contain a series of molecules that collectively are called the respiratory chain. The respiratory chain is the cellular site where most of the energy is derived from foods that we eat. Adequate amounts of oxygen must be available for the chain to function properly and produce the energy-rich molecule ATP. While we might consider only the benefits of getting enough oxygen as we take each breath, most of us are not aware of the potential problems if the oxygen is not quickly used in the mitochondria for energy production. Mitochondrial disease results from a variety of problems with the energy-producing machinery of the patient’s mitochondria. Abnormal mitochondria are unable to reliably and efficiently produce energy and will not use all of the oxygen that is available to them. The unused oxygen may accumulate to the point where it could begin to damage the mitochondria. This is because the presence of excess oxygen in the cells leads to the production of a variety of chemicals known collectively as reactive oxygen species (ROS). Free radicals and other types of ROS can remove electrons from the atoms that make up our cells. Extensive exposure to ROS can lead to oxidative stress, causing extensive damage to any tissues made of cells that contain abnormal mitochondria.

Cells possess several means of protecting themselves against damage from ROS, including antioxidant enzymes. The synthesis of these protective enzymes is regulated by the cellular protein EPAS1/HIF-2a (EH), which responds to oxidative stress by activating specific genes. Upon receiving a signal from EH, these genes direct the production of antioxidant enzymes that will then minimize ROS damage. Dr. Garcia’s lab will screen cells that have been collected from 200 children with mitochondrial disease for the presence of mutated genes that provide the code for the EH regulatory protein. They will then insert these coding errors into cultured cells in the lab to determine the specific nature of the dysfunction associated with the protein.

Dr. Garcia will also work with mice to further understand the regulation of antioxidant enzymes. Loss of EH in mice results in increased levels of ROS and causes them to develop a condition that is similar to mitochondrial disease in humans. This similarity provides an excellent animal model for study of the disease. Dr. Garcia will work both with mice that lack EH and with normal control mice, comparing the capacity of their skeletal muscle cells to produce the energy-containing molecule ATP.

 

Stefan Strack
University of Iowa, Carver College of Medicine

2004 Research Award: $88,000

“Protein phosphatase 2A in mitochondrial function and disease”
Dr. Strack’s laboratory is interested in conducting basic research that could lead to the development of new treatments for mitochondrial disease. Mitochondria are energy-producing organelles contained in most human cells and can cause specific disease conditions when they are damaged. Dr. Strack will develop methods of blocking the activity of a mitochondrial regulatory protein that normally renders brain cells vulnerable to toxin-induced degeneration. His ultimate goal is to find a means of rescuing the cells from the effects of the toxins. His research group is interested in neurodegenerative diseases such as Huntington’s chorea and Parkinson’s disease.

Previous research identified a regulatory protein that is localized to mitochondria in cells of the brain. The protein renders cultured brain cells vulnerable to damage by toxins. If the protein is inhibited, then resistance to the toxins is conferred upon the cells. In his proposal, Dr. Strack suggested that development of drugs against the protein may provide an effective treatment for mitochondrial disease. He will use genetically-engineered viruses to place inhibitors specific to the protein into the brains of rats, followed by testing for resistance to neurotoxins that normally poison the brain. Finding effective means of rescuing the cells from the effects of the toxins could provide insight into prevention of the nervous system degeneration that is typical of some mitochondrial diseases.

 

Brian Robinson
Hospital for Sick Children, Canada 

2004 Research Award: $44,000

“Drug development for the regulation of respiratory chain components in mitochondria”
Dr. Robinson’s research team will screen a large number of chemicals from a family of compounds that show promise for stimulating the production of mitochondrial respiratory proteins. Mitochondria are energy-producing organelles contained in most human cells. They possess a series of energy-producing molecules that collectively are called the respiratory chain and are responsible for synthesizing the energy-rich molecule ATP. Some mitochondrial diseases result from deficiencies of certain respiratory enzymes that are part of the chain. But these defects are rarely total, with some capacity for ATP production remaining. Dr. Robinson’s goal is to look for drugs that could be used to enhance whatever residual activity is present in abnormal mitochondria, so as to increase overall energy production in mitochondrial disease patients.

Prior discovery of two nuclear transcription factors that increase the rate at which mitochondrial respiratory chain proteins are synthesized has led to Dr. Robinson’s suggestion that drugs could be developed to stimulate the activity of these factors. Such stimulation is indeed what happens in response to exercise. Dr. Robinson has access to a large chemical library of heterocyclic compounds that may stimulate the transcription factors in the absence of exercise. He plans to conduct a systematic screening of these chemicals to identify ones that show promise for stimulating the production of mitochondrial respiratory proteins.

 

Gregory M. Enns, MB, ChB
Stanford University, California

2004 Research Award: $34,179

“GSH levels, reactive oxygen species production, lipid peroxidation, products and mitochondrial membrane potential in patients with mitochondrial disease”
Dr. Enns’ laboratory will look for correlations between the relative health status of mitochondrial disease patients and various factors associated with oxidative stress in the patients’ cells. Mitochondria are energy-producing organelles contained in most human cells. They contain a series of molecules that collectively are called the respiratory chain. The respiratory chain is the cellular site where most of the energy is derived from foods that we eat.

Adequate amounts of oxygen must be available for the chain to function properly. While we might consider only the benefits of getting enough oxygen as we take a breath, most of us are not aware of the potential problems that occur if that oxygen is not quickly used in the mitochondria for energy production. Abnormal mitochondria are unable to reliably and efficiently produce energy and will not use all of the oxygen that is available to them.

The unused oxygen may accumulate to the point where it could begin to damage the mitochondria. This is because the presence of excess oxygen in the cells leads to the production of a variety of chemicals known collectively as reactive oxygen species (ROS). Free radicals and other types of ROS can remove electrons from the atoms that make up our cells. Extensive exposure to ROS can lead to oxidative stress, causing extensive damage to any tissues made of cells that contain abnormal mitochondria.

Cells have several ways to protect against damage from ROS, including the glutathione defense system. Dr. Enns’ laboratory will study glutathione levels and oxidative stress in mitochondrial disease patients. Specifically, they will determine the degree of oxidative stress and levels of glutathione in patients when they are outwardly healthy and compare them to times when the patients are acutely ill. Dr. Enns will also measure the extent to which the mitochondria in these patients have been damaged. Measurements of oxidative stress could become a means of providing insights into the effectiveness of patient treatment. Another goal is to assess the potential of a compound known as N-acetylcysteine therapy to decrease the incidence of oxidative stress.

 

Ramon Marti, PhD
Fundacio Institut Hospital Vall d’Hebron, Spain

2004 Research Award: $33,776

“Restoration of thymidine phosphorylase activity in MNGIE patients through platelets infusion”
Dr. Marti’s lab is investigating a rare disease that affects the digestive system. Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a disease of the mitochondria, cell organelles that are responsible for energy production. The severely disrupted digestive function associated with MNGIE typically leads to death in the early adult years. Mitochondria are one example of the complex machines, called organelles, that are found in the human cell. These organelles are made from a variety of proteins. The genetic code required for the manufacture of most these proteins resides in the DNA of the cell’s nucleus. Mitochondria are unique among organelles, however, in that the nucleus does not contain all of the genetic information needed to make them. Some of this information resides in the mitochondria’s own DNA. In order to replicate their own DNA, mitochondria require the activity of an enzyme called thymidine phosphorylase. Unfortunately, a mutation in the gene that provides the genetic code for thymidine phosphorylase causes the production of an abnormal version of the enzyme. The resulting buildup of thymidine, which normally is phosphorylated during the replication of mitochondrial DNA, has a toxic effect on mitochondria and over time will severely diminish the energy-producing capacity of the cells in which these damaged organelles reside.

Platelets, blood cells involved in clotting, contain a number of enzymes and biologically active compounds and are especially rich in thymidine phosphorylase. Dr. Marti plans to infuse MNGIE patients with platelets obtained from healthy blood donors. The expected outcome is that the plasma levels of toxic thymidine in the MNGIE patients will be significantly reduced. Patients will receive platelet infusions every week for one month, during which plasma thymidine levels will be measured and any changes in clinical status will be monitored.

 

Immo Scheffler, PhD
University of California, San Diego

2003 Research Award: $100,000

“Application of RNA interference in the study of NADH-ubiquinone oxidoreductase (complex I) assembly in mammalian mitochondria”
Small interfering RNAs (siRNAs) can nowadays be readily produced in many cells including mammalian cells. RNA interference (RNAi) has become a novel and powerful method to knock down the expression of specific genes in such cells, an alternative to the classical approach utilizing mutations. With the complete knowledge of many of the genomes, any gene can in principle become a target, and hence any protein of interest can be eliminated from a cell to study the physiological and pathological consequences.

Our interest is focused on a large complex in the inner mitochondrial membrane that is essential for respiration (complex I, NADH-quinone oxidoreductase). The complex has a total of 45 subunits, of which 38 are encoded by nuclear genes, and 7 are encoded by mitochondrial genes. Thus, 38 genes are potentially subject to manipulation by RNAi. A fundamental issue is that 14 orthologous proteins in bacteria can perform a very similar function, and the challenge is to elucidate the role of over 30 additional subunits that have been added to the complex in mammalian mitochondria in the course of evolution. RNAi-based technology will for the first time permit a systematic examination of the role of each of these nuclear-encoded subunits in the assembly, stability, activity and regulation of complex I. The insights gained can be applied to the diagnosis and understanding of mitochondrial diseases, particularly the growing class of such diseases resulting from a (partial) complex I deficiency. Partial deficiencies can arise either from a reduced specific activity of the complex or from lower levels due to assembly defects. In the longer term, the technology can be adapted to perform such experiments in whole animals such as a mouse, with the prospect of developing good animal models for the study of the broader physiological and pathological aspects of these diseases.

 

Mikhail Alexeyev, PhD
University of South Alabama

2003 Research Award: $100,000

“Selective Elimination of Defective Mitochondrial Genomes as an Approach to the Reversal of NARP and MILS Syndromes, Heritable Mitochondrial Disorders”
The NARP and MILS syndromes are devastating disorders caused by T8993G mutation in mitochondrial DNA. There exists a compelling evidence that this mutation is the most commonly identified mtDNA mutation in children. Clinically, NARP is characterized by sensory neuropathy, cerebellar ataxia, retinitis pigmentosa, dementia, seizures and developmental delay. MILS, on the other hand, is usually associated with more severe manifestations and early onset (4 to 5 months). Patients with NARP and MILS syndromes are typically heteroplasmic, which means that their cells have both normal and mutant mitochondrial DNA. The difference in the clinical severity is largely due to the mutant load (i.e. % of mutant mtDNAs in every given cell). The life expectancy and quality of life in patients is believed to inversely correlate with mutant load. Thus, patients with MILS have very high mutant loads, typically >90% mutant mtDNA. NARP is usually associated with intermediate mutant loads of 60 to 80%, and mutant loads less than 60% are generally asymptomatic. Therefore, it appears that lowerlng the mutant load below the 60% threshold should be sufficient to render both NARP and MILS patients asymptomatic.

Amazingly, two bacteria, Serratia marcescens and Xanthomonas malvacearum, produce enzymes that can selectively recognize and destroy mutant, but not normal mitochondrial genomes with 99.95% efficiency in a test tube. Therefore, the central idea of this application is to achieve therapeutic effect through targeting of bacterial enzymes to mitochondria. If successful, this approach may allow, for the first time ever, to revert, rather than to just treat, the underlying mitochondrial disease. Our calculations indicate that even if bacterial enzymes will be only 1 % as efficient in mitochondria as they are in a test tube, they still should be able to bring mutant DNA content down below 60% threshold in a patient with 93% mutant mitochondrial DNA. Preliminary data indicate viability of the proposed approach. Thus, the focus of this proposal is to further experimental procedures to target therapeutic enzymes to mitochondria.

 

Matthew Freeman, PhD
Laboratory of Molecular Biology – M.R.C., UK

2003 Research Award: $90,000

“Role of Rhomboid Proteolysis in Optic Atrophy”
Dominant optic atrophy is a genetic disease that causes early childhood blindness with prevalence as high as 1: 10,000 and is the result of defects in a protein called OPA1. OPA1 is a protein that is responsible for maintaining the proper structure and function of the mitochondria, a vital part of the every cell. For OPA1 to function it needs to be cut at the correct place and the correct time by another protein in the cell. We have recently characterized the protein, called Rhomboid, which cuts OPA. We believe that this may be an important step in describing the molecular mechanism of this disease. By using the mouse as a model organism we hope to determine the link between OP A and Rhomboid regulation of mitochondrial function and human optic atrophy.

 

Koji Okamoto, PhD
University of Utah

2003 Research Award: $83,400

“Molecular Basis of Mitochondrial Membrane Dynamics: a New Paradigm of Human Disease”
Mitochondria are dynamic organelles that change size and shape in order to optimize their energy production and supply for cellular functions. Loss of normal mitochondrial morphology results in a variety of human diseases including neurological disorders and some types of cancer. Changes in mitochondrial morphology are also associated with programmed cell death and aging in humans. Although recent findings suggest that deregulation and loss of mitochondrial fusion may contribute to defects associated with mitochondrial diseases, very little is known about the mechanisms that regulate mitochondrial fusion. To understand pathogenesis leading to such diseases, regulatory molecules for mitochondrial fusion must be identified and characterized.

The transmembrane GTPase, called Fzo1 in yeast, is essential for mitochondrial fusion in both yeast and humans. Recent analyses in yeast suggested that GTP hydrolysis by Fzo1 is required for mitochondrial fusion. Regardless of which fusion step requires GTP hydrolysis by Fzo1, it seems very likely that a GTPase-activating protein (GAP) plays a crucial role in modulating mitochondrial fusion. To understand how the GTP-driven molecular device regulates mitochondrial membrane fusion, we will identify a GAP that stimulates GTP hydrolysis by Fzo1 in yeast. We will then analyze this GAP by a combination of biochemical, cell biological and genetic approaches. Moreover, we will investigate the GAP-mediated stimulation of the Fzo1 GTPase activity in vitro.

Since Fzo1 is an evolutionarily conserved GTPase, it is also likely that yeast Fzo1 GAP has a human homologue. What we learn about the mechanism of mitochondrial fusion in budding yeast will be directly relevant to the mechanism of mitochondrial fusion in humans. The proposed project will help determine how the Fzo1 GTPase cycle controls mitochondrial fusion, allowing researchers to investigate the role of regulated fusion and mitochondrial fragmentation during apoptosis. In addition, our research will provide insight into molecular bases for mitochondrial fusion that could contribute to the future development of gene therapies based on inter- mitochondrial complementation. Finally, this study will promote establishment of animal models for understanding pathogenesis of human diseases associated with mitochondrial fusion defects.

 

Bernard Lemire, PhD
University of Alberta, Canada

2003 Research Award: $76,780

“The Use of the Yeast CYB2 Gene As Therapy for Complex I Mutations in a C. elegans Model System”
The mitochondrial respiratory chain (MRC) is the major source of energy for most cells and tissues in the human body. It captures energy from the food we eat by catalyzing the transfer of electrons from NADH, which is derived from that food, to the oxygen we breathe. When MRC function is impaired, NADH accumulates and is diverted towards the formation of lactic acid resulting in lactic acidosis. This condition can produce malaise, weakness, exercise intolerance, and vomiting. It may also contribute to the long-term progression of and developmental delays associated with mitochondrial diseases by modulating the expression of genes related to energy metabolism.

We propose to investigate the use of a yeast enzyme called cytochrome b2 that will directly act to reduce the levels of both lactic acid and NADH. We have isolated and studied a series of complex I MRC mutants that mimic known human mutations in the nematode, Caenorhabditis elegans. The nematode is a very simple animal with an MRC that closely resembles its human counterpart and serves as a sophisticated genetic model system. We will introduce the DNA encoding cytochrome b2 into each of the mutants and evaluate how the yeast protein affects animal fitness as measured by fertility , motility , lifespan, and levels of lactic acid. These results will address the contribution of lactic acidosis to mitochondrial diseases and may lead to the development of a new therapy. Our results will lead to a better understanding of the fundamental biological processes surrounding mitochondrial energy production in normal and in disease states.

 

Giovanni Manfredi, MD, PhD
Weill Medical College of Cornell University, New York

2003 Research Award: $50,000

“MtDNA complementation and recombination in mitochondrial disorders”
Mutations in the mitochondrial DNA (mtDNA) cause mitochondrial diseases. MtDNA is maternally inherited. Thus, mutations in the mtDNA typically result in family pedigrees exhibiting maternal inheritance, i.e. the disease should pass only through females, and essentially all the children inherit the mtDNA mutation. However, despite this simple way of inheritance, the manifestation of mtDNA-related diseases may be very variable even within the same family.

Often, in patients with mitochondrial diseases associated with mtDNA mutations, normal and mutated mtDNAs may coexist within cells and tissues, a condition known as heteroplasmy. An important, but still not well understood, concept in the genetics of mitochondrial diseases is that of complementation in heteroplasmic cells. It is the subject of debate whether in human mitochondria functional complementation between mtDNA molecules is an efficient process or even whether it occurs at all. This is a very important question because if mutant mtDNA molecules function as independent units, unable to interact across different organelles, the protective effect of normal molecules coexisting with the mutated ones (heteroplasmy) would be rather limited.

Moreover, the consequences of randomly occurring new mtDNA mutations, for example acquired during aging, would be more severe in the absence of efficient complementation between normal and mutated mtDNA molecules. This is especially relevant for patients that already harbor an inherited pathogenic mtDNA mutation, in whom the occurrence of acquired mutations may precipitate the clinical phenotype. To address these issues, we have generated a hybrid cell culture model from the fusion of two human cell lines with identical nuclear DNA, but each with a distinct mutation in the mtDNA.

This model allows us to study complementation among mutated mtDNAs in a controlled system. Our goal is to better understand the mechanisms underlying mitochondrial complementation, because we believe that this may contribute to the identification of novel tools for the treatment of these diseases.

 

Philip Schwartz, PhD
Children’s Hospital of Orange County, California

2002 Research Award: $81,574

“Electrophysiologic Properties of Neural Stem Cells from Patients with Mitochondrial Disease”
One of the more prevalent and debilitating features of mitochondrial disease is seizures. Seizures result from uncontrolled electrical activity within the brain. This altered electrical activity may result from changes in any number of basic properties of neurons, the functional cellular units of the brain. Unfortunately, our scientific understanding of the electrical changes in these cells is very incomplete as there has been no way to study neurons with mitochondrial disease while these cells are alive and functioning. Our current understanding of these changes comes only from inferences made from studying EEGs, the responses of patients to various drugs, and the brains of patients that have died with mitochondrial disease.

Recently, my colleagues and I have shown that we can harvest living neural stem cells from the post-mortem human brain, that is from the brain after death of the individual. The same cannot be done for neurons as neurons die very rapidly after death of the individual. Neural stem cells do not. Neural stem cells are immature brain cells that can, in the laboratory, be coaxed into becoming mature neurons. By harvesting neural stem cells from patients that have died with mitochondrial disease and growing these cells in the laboratory, we have produced a living, functioning, brain cell preparation with which we can now study the electrical changes associated with these cells in these same patients.

In the work described in this proposal, therefore, neural stem cells will be harvested from patients with mitochondrial disease and from patients with no neurologic disease (for comparison). This will be done in collaboration with the National Human Neural Stem Cell Resource which I direct. The cells will be grown up in my laboratory and coaxed into becoming electrically active neurons. The electrical properties of these cells, under a variety of conditions, will then be studied in detail. Importantly, we will study not only the basic electrical properties of these cells but also their responses to certain nutrients and drugs so that we may identify better potential anti-seizure treatments for patients with mitochondrial disease.

 

Yidong Bai, PhD
University of Texas Health Science Center at San Antonio

2002 Research Award: $66,000

“Exploiting the potential of yeast NDI1 gene in the therapy of diseases linked with mtDNA”
The mitochondrial complex I, is the largest and least understood component of the energy producing system, consisting at least 43 subunits. Mutations in genes encoding subunits of complex I are associated with diseases, in particular the various forms of Leber’s hereditary optic neuropathy (LHON) that cause blindness. Impaired complex I activities have also been reported to be related to other neurodegenerative diseases and aging. The ability to repair mutations in mitochondrial complex I via gene therapy holds the promise of treatment of mitochondrial diseases such as LHON. In contrast to the multisubunit complex I enzyme found in mammalian cells, the corresponding enzyme in yeast, NDI1, is a single polypeptide. Previously, we showed that the yeast NDI1 is active in a human cell line with an artificial nonsense mutation in mitochondrial DNA (mtDNA) ND4 gene. In this study we plan to further determine if the NDI1 gene can rescue mitochondrial function in cells carrying an mtDNA mutation that causes LHON in humans. More detail analysis of the activities of NDI1 gene in mammalian cells will also be performed. Finally we will initiate the production of transgenic mice expressing a complex I mutation transfected with NDI1 gene. The success of this study will significantly advance our endeavor to use gene therapy for the treatment of mitochondrial disease caused by complex I deficiency.

 

Tanja Taivassalo, PhD
Institute for Exercise & Environmental Medicine, Texas

2002 Research Award: $61,389

“Exercise-induced mitochondrial gene shifting: Resistance training as a therapy for sporadic mtDNA mutations”
A clinical research trial is proposed to determine the efficacy of a novel approach to therapy for selective patients with mitochondrial disorders. The approach is based on the concept of “mitochondrial gene shifting” through exercise training, where resistance exercise is used to shift a patient’s own normal mitochondrial genes from muscle precursor cells into their existing skeletal muscle which contains high levels of abnormal mitochondria and mitochondrial DNA. This has the potential to reverse the accumulation of abnormal mitochondrial DNA that occurs over time within skeletal muscle, restore a more normal function of muscle mitochondria, and thereby increase the energy-generating capacity of the cell. Also, normal adaptive increases in muscle strength associated with resistance training would be expected to further improve overall functional and physical capacity in patients, particularly in those demonstrating muscle weakness in addition to decreased muscle endurance. Due to the non-invasive nature and practicality of this approach, we believe resistance exercise training offers an imminent realistic advance in therapy and will be of functional significance in the quality of life of patients affected with mitochondrial myopathies.

 

 

Jose Hernandez-Yago, PhD
Institute for Cell Research, Spain

2002 Research Award: $41,085

“Transport diseases in mitochondria: Full screening of DNA alterations in human genes encoding TOMM and TIMM complexes in patients with mitochondrial diseases”
The term “mitochondrial diseases” encompasses a heterogeneous group of disorders in which a primary mitochondrial dysfunction is suspected or proven by morphologic, genetic or biochemical criteria. The dual genetic control of mitochondrial proteins and the complex mechanisms needed for their synthesis, transport and correct assembly explain why a variety of genetic errors can cause mitochondrial diseases.

Many mitochondrial diseases suggest dysfunction in the transport processes of mitochondrial proteins from the cytosol to their mitochondrial compartments. We propose in this project the complete screening of the human genes encoding all the subunits of the mitochondrial protein transport machinery (TOMM and TIMM complexes) in patients with mitochondrial diseases as well as in the general population. The finding that the Mohr-Tranebjaerg syndrome-a mitochondrial disease that is a recessive degenerative syndrome characterized by postlingual progressive sensorineural deafness as the first presenting symptom in early childhood, followed by progressive dystonia, spasticity, dysphagia, mental deterioration, paranoia and cortical blindness- is due to defects in the hTimm8a gene, is a significant example of the severe consequences resulting from mitochondrial protein transport dysfunction.

In our laboratory we use a high throughput technology to screen DNA alterations that makes viable the screening of the ca. 100 exons of the approximately 15 subunits of TOMM and TIMM complexes. It is noteworthy that these exons are short enough to be amplified as a whole, using flanking intron primers.

 

Min-Xin Guan, PhD
Children’s Hospital Medical Center, Ohio

2001 Research Award: $33,000

“Biochemical Basis for Maternally Inherited Deafness”
Hearing loss is the most frequent sensory disorder. One in 1000 children is born deaf, an equal number lose their hearing by adulthood and half the population experience significant hearing impairment by the age of 65 years. Deafness can be due to genetic or environmental causes or a combination of both. Despite the recent progress in molecular characterization of deafness, the biochemical and molecular pathogenic mechanisms underlying the maternally inherited deafness remain poorly understood.

Recent results of genetic studies showed that an African-American fanilly with maternally inherited nonsyndromic hearing loss have been associated with the mitochondrial T7 511 C mutation in the tRNA Ser(UCN) gene, which is commonly related to deafness. To elucidate the pathogenic mechanism of this mutation, we have constructed a disease cell model by transferring mitochondria from lymphoblastoid cell lines derived from deaf individuals with mtDNA mutations or from controls lacking mutations, into human mtDNA-less (pO) cells. This application proposes two aims: 1). These transmitochondrial cell lines will be analyzed for the presence and severity of mitochondrial dysfunction associated with mtDNA mutations. 2). To study if over-expression of human mitochondrial Seryl-tRNA synthetase in these transmitochondrial cell lines can suppress the biochemical phenotype associated with T7511C mutation.

Success of this project will enhance a better understanding of pathogenic mechanisms of matemally inherited deafness, lead to the future therapies directed toward specific underlying abnormalities, and the development of animal models to test them.

 

Brian Robinson, PhD
The Hospital for Sick Children, Canada

2001 Research Award: $15,000

“Efficacy of prenatal diagnosis of mitochondrial diseases.”
Prenatal diagnosis of mitochondrial diseases by examination of biochemical metabolite or enzyme profiles is undoubtedly possible, at least for some types of disease. We propose that the biochemical abnormalities in fibroblasts of affected children can be documented and used to carry out prenatal diagnosis in amniotic cell cultures. While we have been collecting data from prenatal diagnosis of nuclear-encoded mitochondrial diseases for a number of years, this data set is far from complete. We have had one year of funding from UMDF to continue this project, one more year of funding should allow us to complete our studies and make some conclusions. This project will be funded to see if this hypothesis can be verified for a number of mitochondrial diseases to include cytochrome oxidase deficiency, complex I deficiency and pyruvate dehydrogenase complex deficiency.

 

Edwin Kirk, MD
Sydney Children’s Hospital, Australia

2001 Research Award: $12,000

“Complex I: The role of nuclear genes in disorders of childhood due to mitochondrial Complex I deficiency.”
Complex I is a collection of proteins located in the mitochondria of the cell. These proteins work together to drive the first steps in the production of energy. Children with Complex I deficiency, often suffer devastating consequences such as deterioration of brain, muscle and other organ function.

They often die in the first years of life. Complex I deficiency is a genetic disorder, but in most cases, the underlying genetic fault is not known. There are at least 42 different protein building blocks which combine to make Complex I, each of which is coded for by a different gene. Because there are so many possible genes involved, finding the gene fault in a child with Complex I deficiency has been a very difficult task. Recently, however, a group of scientists in the Netherlands looked at 8 complex I genes which seem to be particularly important (because they have changed the least during evolution).

They found gene faults (mutations) in a total of 5 out of 20 families. We have samples from 40 children with proven complex I deficiency available for this study. This is a unique resource and represents all children in Australia with confirmed Complex I deficiency. We plan to search for mutations in the 8 important genes mentioned above, in the 40 families for whom we have DNA samples. If a mutation is found in a family, then the child’s medical history will be reviewed. We will seek to identify patterns in the types of problems experienced by children with faults in each gene, to try to guide searches for faulty genes in future patients. If the faulty gene in a family is identified, it will enable us to provide answers for the family about the cause of the condition and how it is inherited in their family. For some, this information may also provide the option of testing future pregnancies to find out whether the baby is affected.

 

Dikoma Shungu, PhD
Columbia University, New York

2000 Research Award: $36,719

“Quantitative In Vivo 1H Magnetic Resonance Spectroscopic Imaging of Cerebral Lactate as a Screening Test for Mitochondrial Disorders”
This research will seek to develop a test for screening patients suspected of having a mitochondrial disease. The test will be noninvasive in that it will be based on using magnetic resonance spectroscopic imaging (MRSI)—a technique that is nearly identical to standard MRI, except that it can measure levels of various biochemicals in the human body—to precisely quantify levels of lactic acid in the cerebrospinal fluid (CSF) of suspected patients. We believe this to be worthwhile because studies we have conducted over the past 5 years on many patients with mitochondrial diseases have shown that a large proportion of these patients have measurable levels of lactic acid in their CSF, whereas control individuals did not. If further refined, this technique for measuring lactate in the CSF may prove to be a very useful tool for screening patients with mitochondrial diseases, and helping assess the degree of severity of the disease and its progression in future clinical trials of promising therapies.

 

George Perry, MD
Case Western Reserve University, Ohio

2000 Research Award: $18,281

“Is oxidative damage a result of metabolic abnormalities in Alzheimer disease?”
Evidence continues to accumulate that increased oxidative damage is important in Alzheimer disease (AD) and may be the biochemical basis of the increased incidence of AD with aging. In published studies, we have shown oxidative damage affects every neuron in susceptible neuronal populations in cases of AD, but not in normal people. In unpublished studies, we show that the only abnormality of vulnerable neurons in AD is changes in mitochondria. This proposal will specifically investigate the idea that oxidative damage in AD begins as mitochondrial abnormalities. To address this issue, we will 1) determine the relationship between oxidative damage, mitochondrial abnormalities and the pathology of the disease; and 2) determine whether some of the relationships noted in Aim 1 for AD hold true in Down syndrome. Completion of these aims will help to define the relationship of oxidative damage to mitochondrial abnormalities.

 

Cecilia Giulivi, PhD
University of Minnesota, Duluth

1999 Research Award: $31,137

“Characterization of Mitochondrial Nitric-Oxide Synthase”
Expansion of the field of mitochondrial disease can be anticipated in several directions. First, into age-related degenerative diseases; second, into areas connected with new concepts in mitochondrial biochemistry and physiology. Of great interest are thorough studies aiming at a better understanding of the processes underlying mitochondrial defects. In this context, the recent finding of an enzyme, i.e., mitochondrial nitric-oxide synthase, that generates nitric-oxide, well-known modulator of important biological processes such as immunity, vasodilation, and neurotransmission, offers a new perspective in mitochondrial bioenergetics. We reported that the production of nitric-oxide by mitochondria modulates the synthesis of ATP; this latter compound constitutes the currency that supports cellular work. Considering the important role that nitric-oxide might have on ATP generation, this project is aimed at identifying the nitric-oxide synthase in different tissues, providing basis for future studies that will address strategies for attempts at the treatment of mitochondrial diseases associated with a defective enzymatic expression.

 

Brian Robinson, PhD
The Hospital for Sick Children, Canada

1999 Research Award: $8,863

“Efficacy of Prenatal Diagnosis of Mitochondrial Diseases”
Prenatal diagnosis of mitochondrial diseases by examination of biochemical metabolite or enzyme profiles is undoubtedly possible, at least for some types of disease. We propose that the biochemical abnormalities in fibroblasts of affected children can be documented and used to carry out prenatal diagnosis in amniotic cell cultures. While we have been collecting data from prenatal diagnosis of nuclear-encoded mitochondrial diseases for a number of years under a small program funded by the US March of Dimes, this data set is far from complete. This project will be funded to see if this hypothesis can be verified for a number of mitochondrial diseases to include cytochrome oxidase deficiency, Complex I deficiency and pyruvate dehydrogenase complex deficiency.

 

John Shoffner, MD
Horizon Molecular Laboratory, Georgia

1998 Research Award: $30,000

“Gene mutations in Leigh’s Disease”
Leigh’s disease is a disorder in which degeneration in the basal ganglia structures, brainstem, and cerebellum cause considerable morbidity and mortality. Although most patients with Leigh’s disease harbor defects in oxidative phosphorylation, mtDNA mutations are identified in less than 20% of cases when screening for known mtDNA mutations is performed. From 66 cases with Leigh’s disease, we will select cases and test for mitochondrial DNA mutations based on the clinical features and biochemistry results. If the selected patients do not harbor mtDNA mutations, we will begin looking at specific types of mutations involving complex I genes that are found in the nuclear DNA.

 

Carolyn Bay, MD
Children’s Hospital of Pittsburgh

1998 Research Award: $5,000

“Mitochondrial etiologies of pseudoobstruction and dysmotility in children”
Approximately 75-100 children with serious, and chronic intestinal symptoms called pseudoobstruction and/or dysmotility, will participate in this 2 year study of potential mitochondrial etiologies. In addition to their pediatric gastrointestinal evaluation, the children will be evaluated from a genetic and medical genetic laboratory perspective. The purpose is to provide an explanation for the child’s symptoms, and to determine how frequently rnitochondrial disorders are the underlying reason for the child’s severe gastrointestinal problems. This will be done by a careful pediatric history, including a family tree, and physical examination. All children will have DNA isolated, and we will test for the mtDNA 3243 mutation. Then we will determine if additional mitochondrial testing is indicated. If agreed to by the family and the gastroenterologists, we will arrange for additional testing of other mitochondrial disorders. By testing the most frequently associated mitochondrial abnormalities known to cause these specific gastrointestinal problems of dysmotility and pseudoobstruction, we hope to learn the prevalence of mitochondrial disease in this group of pediatric patients. This information will provide additional insight into the spectrum of gastrointestinal problems that a child with a mitochondrial disorder might experience. We hope that an accurate diagnosis will provide further insight into improved treatment strategies for children experiencing these symptoms.

 

Richard Boles, MD
Children’s Hospital of Los Angeles

1998 Research Award: $30,000

“Search for Pathogenic Mitochondrial DNA Mutations Using Temporal Temperature Gradient Gel Electrophoresis (TTGE)”
Mutations of mitochondrial DNA (mtDNA) have been found in children with a wide variety of different disease manifestations and, due to its high mutation rate, are believed to be the underlying cause in a sizable fraction of children with mitochondrial disorders. Past efforts to identify mtDNA mutations in children have been hampered by the size of the mtDNA and the difficulty in distinguishing disease causing mutations from the numerous normal sequence variations found in mtDNA (‘polymorphisms’). Most, if not all, children with mtDNA mutations have coexisting normal and mutant mtDNA (‘heteroplasmy’), suggesting that a heteroplasmy detection method might be an effective method to screen populations for mtDNA disorders. Polymorphisms are almost always homoplasmic (single type of mtDNA).

A new mutation detection method, TTGE, was adapted in our laboratory for use with mtDNA. TTGE is rapid, inexpensive and very sensitive with 100% of known mtDNA mutations detected to date. Heteroplasmy (mutation) was clearly distinguishable from polymorphisms. At present we have used this method to scan 1/3 of the mtDNA, and we plan to extend the covered area to screen all of the mtDNA for mutation. After this we plan to use this technique to screen specific populations, including children with mitochondrial disorders, mental retardation, epilepsy, sudden infant death, etc. for mtDNA mutations. Our preliminary data in screening only 10% of the mtDNA sequence in 100 patients with suspected mitochondrial disease revealed 7 cases of heteroplasmy (mutation). This data demonstrates the power of TTGE to detect mtDNA mutations and suggests that mtDNA disorders are far more common than previously demonstrated. TTGE has great potential as a clinical screening test for general usage in patients with suspected mitochondrial disease. Detection of a mtDNA mutation could benefit families by allowing for presymptomatic and prenatal diagnosis in addition to providing a definitive diagnosis and more accurate genetic counseling.