Meeting Abstract

146.6  Monday, Jan. 7  Epigenetic regulation of myogenesis in a growth paradigm-specific manner. BIGA, PR*; FROEHLICH, JM; University of Alabama at Birmingham ; University of Alabama at Birmingham pegbiga@uab.edu

Piscine growth is unique in that many species exhibit patterns of muscle growth opposite that of mammalian species. Many teleosts exhibit hyperplastic muscle growth throughout their lives, while most mammals only exhibit hyperplasia during fetal growth or following trauma. Recently, we have characterized closely related fish species that exhibit different growth types: zebrafish (determinate-like) and giant danio (indeterminate). The zebrafish (Danio rerio) has been used extensively as a model system for developmental studies but, unlike most teleost fish, it grows more determinately. A close relative, the giant danio (Devario cf. aequipinnatus), grows indeterminately, displaying both hyperplasia and hypertrophy in muscle as an adult. Interestingly, the adult giant danio exhibits a significant increase in body mass following growth hormone treatment, while the adult zebrafish fails to respond with more than a 10% increase in growth. To better understand the underlying mechanisms of growth paradigm differentiation, we have begun to characterize potential methods of epigenetic regulation of myogenic regulating factors between these two opposing growth types. Methylation of lysine residues on histone 3 (H3) has been shown to repress muscle-differentiation-specific gene promoters in mammals. Here we demonstrate differential patterns of epigenetic regulation between closely-related fish species exhibiting opposing growth paradigms, where hypermethylation of several lysine residues is associated with the Myf5 promoter in myogenic precursor cells (MPCs) from adult giant danio myotomal tissue. Giant danio MPCs do not express Myf5 protein during in vitro myogenesis, suggesting that epigenetic regulation may play a pivotal role in growth paradigm potential.