Over the last 5 years, we have been working to establish the zebrafish as a model for musculardystrophy. In this capacity, we have published the phenotype of zebrafish lacking dystrophin and 8-sarcoglycan, completed a large genetic screen to isolate additional dystrophic mutants, and identified themutant gene in the runzelmutant. Using our experiences in muscle research and in establishing thezebrafish as a disease model, we now propose to use the fish to investigate the pathogenesis of musculardystrophy and evaluate cell therapy as a potential treatment option.
The first aim i n this project proposes to fully characterize two of our available dystrophic zebrafishmodels (emz and sof) with the goal of better understanding the pathogenesis of muscular dystrophy. Thesemutants show a muscle degeneration phenotype very similar to the dystrophin mutant (sapje) suggestingthat this phenotype is symptomatic of muscular dystrophy. We propose to identify the genetic mutations inthese mutants using a traditional mapping approach and then sequencing candidate genes to identify thespecific mutation. If the orthologous human genes are not currently associated with muscular dystrophy,these genes will be considered disease candidate genes and sequenced in human patients for which thecause of muscular dystrophy is unknown. Since mutations in seemingly unrelated proteins can manifest asmuscular dystrophy, the identification of additional genes would be helpful for establishing disease pathways. Secondly, we have established methods to transplant cell populations in zebrafish at alldevelopmental stages and now propose using this system to identify the cell population most capable ofengrafting into and correcting the diseased muscle. Gene expression profiles of muscle engrafting cellpopulations will be compared with non-engrafting cells to identify genes expressed predominantly in theengrafting cells. Differentially expressed genes will be considered potential markers and used to purifyanalogous cell populations in mammals for future experimentation and therapy. Finally, we plan to dissectthe lineage relationship of various stem cell populations by assaying the developmental potential of zebrafishmuscle progenitor cells. This will be accomplished by transplanting limited populations of labeled cells earlyin development and then following their fate as the fish matures.
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