MicroRNA-95 promotes myogenic differentiation by downregulation of aminoacyl-tRNA synthase complex-interacting multifunctional protein 2

Abstract

MicroRNA-95 (miR-95) is well known for its ability to promote the proliferation of a variety of cancer cells, but its function in skeletal muscle development has not been reported so far. Our laboratory has recently generated genetically engineered Meishan pigs containing a loss-of-function myostatin (MSTN) mutant (MSTN-/-). These MSTN-/- pigs grow and develop normally but show clear double muscle phenotype as observed in Belgian cattle. We observed that the expression of miR-95 was upregulated in the longissimus dorsi from MSTN-/- Meishan pigs at day 65 during embryo development. In this study, we investigated the role of miR-95 in the myogenic differentiation using a murine myoblast cell line C2C12. Our results revealed that miR-95 may play a very important role in regulating the expression of myogenic differentiation marker genes myosin heavy chain (MHC) and myogenin. By use of bioinformatical analysis and luciferase reporter gene assay, aminoacyl-tRNA synthase complex-interacting multifunctional protein 2 (AIMP2) gene was identified as a miR- 95 target gene involved in myogenic differentiation. Our results indicated that higher miR-95 expression level leads to lower level of AIMP2 protein expression. When the endogenous expression of AIMP2 is inhibited by siRNA, the expression levels of myogenic differentiation marker genes MHC and myogenin increased, implying that AIMP2 negatively regulates myogenic differentiation. Taken together, it is likely that miR-95 promotes myogenic differentiation in C2C12 myoblasts and may play a positive functional role in skeletal muscle development by down regulating the expression of AIMP2 at protein level.