Satellite cell activation in adult zebrafish (Danio rerio) single muscle fibre cultures

Satellite cells (SCs) are muscle stem cells that stay in a metabolically and mitotically quiescent state in adult skeletal muscle until activated. In mammals, SCs are activated and enter into the cell cycle for growth and regeneration. The mechanism initiating SC activation in vivo and in vitro, mediated by nitric oxide (NO) and hepatocyte growth factor (HGF) is described in the mouse model, but not in other species. Here, we assessed SC activation by counting bromodeoxyuridine (BrdU)-immuno-positive cells, and found that SC activation in zebrafish single muscle-fibre cultures is also NO and HGF dependent, peaking at 1 mM isosorbide dinitrate (ISDN, an NO donor drug) and 10 ng/mL HGF respectively, using dose-response experiments. Moreover, HGF signalling via the c-Met receptor is involved in the SC activation pathway and is considerably affected by temperature (i.e., 21 °C). Overall, understanding NO-HGF-c-Met signalling in SC activation gives new insights on fish muscle growth and conservation of regulatory pathways between species.