Establishment of myoblast cell line and identification of key genes regulating myoblast differentiation in a marine teleost, Sebastes schlegelii.

Skeletal myoblasts are activated satellite cells capable of proliferation and differentiation. Studies on mammalian myoblast differentiation and myogenesis could be carried out in vitro thanks to the availability of mouse myoblast cell line C2C12. Lacking of muscle cell line hinders the studies of teleost fish myogenesis. Here, we established a continuous skeletal muscle cell line from juvenile rockfish (Sebastes schlegelii) muscle using explant method and subcultured more than 50 passages for over 150 days. Stable expression of myoblast-specific marker, MyoD (myoblast determination protein) and the potential of differentiation into multi-nucleated skeletal myotubes upon induction suggested the cell line were predominately composed of myoblasts. Transcriptome analysis revealed a total of 4375 genes differentially expressed at four time points after the switch to differentiation medium, which were mainly involved in proliferation and differentiation of myoblasts. KIF22 (kinesin family member 22) and POLA1 (DNA polymerase alpha 1) were identified as the key genes involved in fish myoblast proliferation whereas MYL3 (myosin light chain 3) and TNNT2 (troponin T2) were determined as the crucial genes responsible for differentiation. In all, the continuous myoblasts cultured in this study provided a cell platform for future studies on marine fish myoblast differentiation and myogenesis. The molecular process of myoblast differentiation revealed in this study will open a window into the understanding of indeterminate muscle growth of large teleost.