View Program - 63rd Annual Drosophila Research Conference

The Drosophila gene Holes in muscles (Him) is a mesodermal transcriptional corepressor that functions in myogenesis. Previously, we and others have characterized Him expression in the early embryonic mesoderm where it functions downstream of known muscle specification genes as a repressor of the myogenic transcription factor MEF2 to delay muscle differentiation until the appropriate stage. Here, we extend our analysis of Him to other stages of Drosophila muscle development and function by analyzing the phenotype of the first-generated Him mutant allele. Him mutants show a reduction in the imaginal disc associated myoblast pool that form the adult thoracic muscles, including those required for jump and flight. Consistent with this observation, we find that Him mutants have reduced myonuclei in adult differentiated flight muscles. To further characterize the role of Him in adult muscle function, we assayed flight performance in young and aged flies. Him mutants perform comparably to wild type controls at young (3-5 days) of age, however have significantly reduced flight ability at two weeks of age, suggesting a role for Him in continued muscle maintenance. Additionally, we find that the flightless phenotype correlates with the number of somatic muscle stem cells associated with the flight muscles. Young Him mutants and control flies have a similar number of stem cells, but this number is significantly reduced in the mutants at two weeks of age. Altogether, these data suggest an ongoing role for Him in muscle beyond early development potentially mediated through regulating myonuclear number and stem cell maintenance.

Drosophila Holes in muscles is required for ongoing adult muscle function and muscle stem cell maintenance.