microRNA133a targets Foxl2 and promotes differentiation of C2C12 into myogenic progenitor cells.

microRNAs are endogenous noncoding RNA molecules of ∼22 nucleotides that regulate gene function by modification of target mRNAs. Due to tissue specific of miR-133a and miR-1/206 for skeletal muscles, we investigated the role of miR-133a and miR-1/206 in promoting the differentiation of the C2C12 cells. The results show that directly transfecting mature miR-133a, miR-1/206, or combinations (miR-1 and miR-206, miR-1 and miR-133a, and miR-133a and miR-206) into C2C12 cells, respectively, for 5 days induces formation of myogenic progenitor cells. Overexpression of miR-133a and miR-206 in C2C12 cells greatly improved multinucleated myotube formation. microRNA-133a (miR-133a) is highly expressed during human muscle development. Using bioinformatics, we identified one putative miR-133a binding site within the 3'-untranslated region of the mouse Foxl2 mRNA. The expression of Foxl2 was shown to be downregulated by subsequent western blot analysis.