miR-27b-3p Was Involved in Retinoic Acid-induced Abnormal Early Myogenic Differentiation of C2C12 Cells via Targeting CaMKIIδ

Abstract

Myogenic diff erentiation is an important stage within the multi-step process of skeletal muscle development. We previously found that excess retinoic acid (RA) could induce derangement of myofi laments in the embryonic tongue by inhibiting diff erentiation through Wnt5a/CaMKIIδ (calcium/calmodulin-dependent protein kinase II delta) pathway. Furthermore, our recently studies indicated that excess RA can directly induce abnormal expression of series of miRNAs in embryonic tongue, including miR-27b-3p. miR-27b-3p has been reported as a regulator involved in kinds of tumors development. In addition, miR-27 was proved to negatively regulate adipogenesis. It has been indicated that miR-27b could down-regulate the expression of Pax3 and Pax7 and thus inhibits myoblast proliferation. Here, we found that the expression of miR-27b-3p increased at early stage of myogenic diff erentiation (diff erentiation day 2, D2) in RA-treated C2C12 cells, but CaMKIIδ expression was reduced. Furthermore, bioinformatics analysis predicted that miR-27b-3p targets the 3'UTR of CaMKIIδ. The direct interaction between of miR-27b-3p and CaMKIIδ was confi rmed by luciferase reporter assays. More importantly, rescue experiments indicated that CaMKIIδ mediated miR-27b-3p to regulate the early diff erentiation defects induced by excess RA, and which was achieved mainly via Myogenin. In conclusion, excess RA disturbed the early diff erentiation of C2C12 cells by stimulating miR-27b-3p expression which targeted CaMKIIδ, and then controlled the expression of Myogenin, those above implying new mechanism in myogenic diff erentiation and miR27b-3p may act as a new biomarker for muscle disease.