FHL3 negatively regulates the differentiation of skeletal muscle satellite cells in chicken

As a member of four and a half LIM domain proteins, FHL3 gene-encoded protein (FHL3) plays an important role in skeletal muscle development and contraction. In this study, we determined the potential role of FHL3 in the proliferation and differentiation of primary satellite cells in chicken. RT-qPCR results showed that FHL3 mRNA was highly expressed in skeletal muscle in 12 chicken tissues. Four cell proliferation assays (CCK8 assay; EDU staining assay; flow cytometric detection of cell cycle assay; and detection of cell proliferation marker genes Ki67 and N-Ras assay) revealed that FHL3 knockdown had no effect on the proliferation rate of chicken satellite cells. FHL3 knockdown promoted the differentiation of satellite cells into myotubes, as evidenced by increased fusion index, number of nuclei per myotube, Myog, Myh7, Myf5, and Mrf4 mRNA expressions, and myog and myosin heavy chain protein expressions of myogenic markers (P < 0.05). These results showed that the FHL3 was a negative regulator of the differentiation and fusion of chicken satellite cells into myotubes. However, FHL3 expression was increased during the differentiation of chicken satellite cells into myotubes. The study suggested that FHL3 might have different functions in chicken myotubes compared with that in chicken satellite cells.