Expression of TGFbeta family members during myogenesis resumption in rainbow trout
Résumé
The TGFbeta family is composed of numerous members that are involved in the regulation of several cellular processes such as proliferation, differentiation, apoptosis, etc. In fish, among all these factors, only the function of myostatin (also known as GDF8) on muscle growth have been extensively studied. For all others members such as TGFbeta1, TGFbeta2, TGFbeta3 and Inhibin, the regulation of their expression during myogenesis is unknown. In an attempt to determine whether these growth factors could be involved in the regulation of muscle growth we first look for the presence of gene paralogs in trout. Second, we measured their expression during fasting-refeeding experiment known to induce myogenesis resumption. In silico analysis, show that it exists several paralogs for TGFbeta1 and inhibin but not for TGFbeta2 and TGFbeta3 found in a single copy. The analysis of their tissue expression pattern reveals that each paralog had a specific expression patterns. In addition, all these factors were expressed in white muscle, the TGFbeta3 having the strongest expression level. Fasting and refeeding strongly affected the expression of these growth factors. Fasting period affected the expression of TGFbeta1 and TGFbeta2 but not that one of TGFbeta3 whereas refeeding modified mainly the expression of TGFbeta3. In conclusion, these data suggest that others TGFbeta than myostatin could have a function in muscle growth regulation in fish. Works are in progress to characterize the expression of these growth factors during the differentiation of satellite cells.