MyoD is regulated by the miR-29a-Tet1 pathway in C2C12 myoblast cells

Skeletal myogenesis is regulated by a considerable number of microRNAs (miRNAs). miRNA regulatory networks are complicated, and details of how they operate remain unclear. In this study, MTT assays confirmed that miR-29a is the most effective miR-29 paralog. Microarray analysis demonstrated upregulation of ten-eleven translocation enzyme-1 (Tet1) mRNA in response to miR-29a inhibition in C2C12 murine myoblast cells. We investigated the factors acting downstream in the miR-29a-Tet1 signal pathway using real-time RT-PCR. MyoD expression was upregulated by Tet1 inhibition and downregulated by miR-29a inhibition, whereas expression of cyclin-dependent kinase 6 (Cdk6) was regulated in an opposite manner. These results suggest that the miR-29a-Tet1 pathway upregulates MyoD expression and conversely downregulates Cdk6 expression. However, changes in the expression of other myogenic factors such as serum response factor (Srf), the myocyte enhancer factor 2 family (Mef2a, b and c), myogenin, myogenic regulatory factor 4 (Mrf4), muscle creatine kinase (Mck), and other cell cycle regulators such as Cdk4 and thymine DNA glycosylase (Tdg) cannot be explained in terms of the miR-29a-Tet1 pathway alone. The miR29a-Tet1 pathway may be part of a complex myogenic regulatory network in C2C12 cells. (J Oral Sci 58, 219-229, 2016).