As a scientist and a clinician, I am interested in genes that play a role in the development of heart failure. While the dystrophin gene is best known for its role in Duchenne Muscular Dystrophy, mutations in the dystrophin gene also cause a familial X-linked Dilated Cardiomyopathy syndrome. Dystrophin is a large cytoskeletal protein that links actin in muscle to the sarcolemma through a complex of dystrophin-associated glycoproteins (DAGs). The DAGs are secondarily diminished in dystrophic muscle leading to the hypothesis that it is this decrease that leads to myopathy.
I aim to characterize genes encoding muscle-specific components of the DAG complex to understand their role in normal cardiac muscle function and to investigate whether these genes are mutated in autosomal forms of muscular dystrophy and cardiomyopathy. In the laboratory of Dr. Louis Kunkel, I isolated and characterized the gene encoding the human 50 kD DAG known as adhalin. Immunostaining for adhalin and the 35 kD DAG is specifically diminished in the skeletal muscles of patients with Autosomal Recessive Duchenne-like Muscular Dystrophy (ARDLMD). Studies of families with ARDLMD have revealed genetic linkage to markers on chromosome 13. I mapped the adhalin gene to chromosome 17, excluding adhalin as the cause of the chromosome 13-linked ARDLMD. I propose to isolate the gene encoding the 35 kD DAG using degenerative oligonucleotide primers based on sequence derived from proteolytic fragments of the 35 kD DAG. I will determine the chromosomal location of the gene encoding the 35 kD DAG by PCR analysis of human/rodent somatic cell hybrids and fluorescence in situ hybridization. I plan to develop skills in genetics and pedigree mutational analysis by investigating whether the genes encoding these proteins are involved in cardiomyopathy and muscular dystrophy. Finally, I propose to generate antibodies to adhalin and the 35 kD DAG using peptides derived from their cDNA sequences. Using these antibodies, I will study the intracellular location and potential interactions of these proteins. These experiments will improve our understanding of the DAG complex and its role in the pathogenesis of myopathy. These experiments will also allow me to personally develop my skills as a scientist to become an independent investigator. I propose to perform these experiments in the laboratory of and under the guidance of Dr. Louis Kunkel who originally identified the gene and the mutations that cause Duchenne Muscular Dystrophy. Dr. Kunkel has a continuing interest in the genetics of neuromuscular disorders and his laboratory provides an ideal environment for this undertaking.
|McNally, E M; Ly, C T; Kunkel, L M (1998) Human epsilon-sarcoglycan is highly related to alpha-sarcoglycan (adhalin), the limb girdle muscular dystrophy 2D gene. FEBS Lett 422:27-32|
|Messina, D N; Speer, M C; Pericak-Vance, M A et al. (1997) Linkage of familial dilated cardiomyopathy with conduction defect and muscular dystrophy to chromosome 6q23. Am J Hum Genet 61:909-17|
|Vainzof, M; Passos-Bueno, M R; Canovas, M et al. (1996) The sarcoglycan complex in the six autosomal recessive limb-girdle muscular dystrophies. Hum Mol Genet 5:1963-9|
|McNally, E M; Duggan, D; Gorospe, J R et al. (1996) Mutations that disrupt the carboxyl-terminus of gamma-sarcoglycan cause muscular dystrophy. Hum Mol Genet 5:1841-7|
|McNally, E M; Passos-Bueno, M R; Bonnemann, C G et al. (1996) Mild and severe muscular dystrophy caused by a single gamma-sarcoglycan mutation. Am J Hum Genet 59:1040-7|