FHL1 regulates myoblast differentiation and autophagy through its interaction with LC3

Four and a half LIM domain protein 1 (FHL1) belongs to the FHL protein family and is predominantly expressed in skeletal and cardiac muscle. FHL1 acts as a scaffold during sarcomere assembly and plays a vital role in muscle growth and development. Autophagy is key to skeletal muscle development and regeneration, with its dysfunction associated with a range of muscular pathologies and disorders. In this study, we constructed FHL1-silenced or FHL1-overexpressed myoblasts to investigate its role in autophagy during the differentiation of chicken myoblasts into myotubules. Our data showed that FHL1 contributes to myoblast differentiation as measured through MyoG, MyoD, Myh3, and Mb mRNA expression, MyoG and MyHC protein expression and the morphological characteristics of myoblasts. The results showed that FHL1 silencing inhibited the expression of ATG5 and ATG7, meanwhile, immunofluorescence and immunoprecipitation showed that FHL1 and LC3 interacted to regulate the correct formation of autophagosomes. FHL1 inhibition increased cleaved caspase-3 and PARP abundance and promoted myoblast apoptosis. Furthermore, FHL1 rescued skeletal muscle atrophy through regulating the expression of Atrogin-1 and MuRF1. Taken together, these data suggested that FHL1 regulates chicken myoblast differentiation through its interaction with LC3.