Characterization of myogenesis in European sea bass (Dicentrarchus labrax) using primary white muscle cell cultures

This study presents the first characterization of a primary cell culture from white skeletal muscle of European sea bass (Dicentrarchus labrax). Using immunofluorescence and gene expression analyses over 12 days, cell activation, proliferation, differentiation, fusion, and maturation phases were described. During culture development, myogenic regulatory factors (myf5, myod1, myod2, myog, mrf4) were sequentially expressed. Proliferation peaked at days 4-6, with high Pcna and Myod immunodetection and gene expression of pax7, c-met, and pcna. Early downregulation of cell cycle regulators, cdkn1a and cdkn1cb, and mstnb may have contributed to proliferation, while cdkn1bb progressively increased, likely to promote differentiation. The Gh/Igf axis showed differential regulation, igf-1 decreasing early and igf-2, igf-1ra, igf-1rb, and igfbp-1a gradually rising. Differentiation, myotube formation, and maturation were marked by higher Myhc staining, sarcomere development, and upregulation of cdh15, cav3, mef2, mymk, mymx, myhcb, and wnt4. Anabolic (akt2, mtor, eif4ebp1) and proteolytic-related genes (foxo1a, murf1, mafbx, capn1, capn3b, atg12, map1lc3b) increased in later stages. Comparison with other vertebrates revealed both conserved and species-specific regulatory mechanisms of myogenesis. These findings provide a comprehensive molecular framework of skeletal muscle development in European sea bass and establish a valuable in vitro model for studying fish muscle biology and potential aquaculture and biotechnology applications.