摘要The proliferation and differentiation of myoblasts are considered the key biological processes in muscle develop-ment and muscle-related diseases,in which the miRNAs involved remain incompletely understood.Previous re-search reported that miR-424(322)-5p is highly expressed in mouse skeletal muscle.Therefore,C2C12 cells are used as a model to clarify the effect of miR-424(322)-5p on the proliferation and differentiation of myoblasts.The data show that miR-424(322)-5p exhibits a decreasing trend upon myogenic differentiation.Overexpression of miR-424(322)-5p inhibits the proliferation of myoblasts,manifested by downregulation of proliferation marker genes(CCNB1,CCND2,and CDK4),decreased percentage of EdU+cells,and reduced cell viability.In contrast,these phenotypes are promoted in myoblasts treated with an inhibitor of miR-424(322)-5p.Interestingly,its gain of function inhibits the expression of myogenic regulators,including MyoD,MyoG,MyHC,and Myf5.Additionally,immunofluorescence staining of MyHC and MyoD shows that overexpression of miR-424(322)-5p reduces the number of myotubes and decreases the myotube fusion index.Consistently,inhibition of its function mediated by an inhibitor promotes the expressions of myogenic markers and myotube fusion.Mechanistically,gene prediction and dual-luciferase reporter experiments confirm that enhancer of zeste homolog 1(Ezh1)is one of the targets of miR-424(322)-5p.Furthermore,knockdown of Ezh1 inhibits the proliferation and differentiation of myoblasts.Compared with NC and inhibitor treatment,inhibitor+si-EZH1 treatment rescues the phenotypes of proliferation and differentiation mediated by the miR-424(322)-5p inhibitor.Taken together,these data indicate that miR-424(322)-5p targets Ezh1 to negatively regulate the proliferation and differentiation of myoblasts.