Cyclin-dependent Kinase 9 Induces Regional and Global Genomic DNA Methylation Via Influencing DNMT Gene Expression in Mouse Myoblast C2C12 Cells During Differentiation

Cyclin-dependent kinases (CDKs) including Cdk9 have been associated with cardiac differentiation. The increasing evidence has proposed that Cdk9 overexpression can regulate the epigenome. However, the current research is the first report of the Cdk9 affection on the regional and global DNA methylation during differentiation.

This study examined the effects of Cdk9 overexpression on the regional methylation patterns of cardiac miRNAs (miR-1, -133, -206) and myogenic regulatory factors (i.e., MyoD and Myogenin) and promoter DNA methylation in mouse myoblast C2C12 cells during differentiation by the methylation-specific polymerase chain reaction (MSP-PCR) method. Moreover, the mRNA expression levels of DNMT1, DNMT3A, DNMT3B, and global 5-methyl cytosine (5-mC) levels in mouse myoblast C2C12 cells were quantified during differentiation by RT-qPCR and ELISA methods, respectively.

The results demonstrated that Cdk9 overexpression results in DNA methylation changes in mouse myoblast C2C12 cells. It was found that the average expression levels of DNMTs in line with global DNA methylation significantly increased in Cdk9 transfected cells upon Cdk9 overexpression (P<0.05). In addition, the results showed that the regional promoter methylation of miR-1 and miR-133 genes increased in transfected cells during differentiation. An interesting possibility raised by our study is that further active global DNA methylation observed in Cdk9-transfected C2C12 cells can be clarified through the increased DNMT expression by Cdk9 in these cells.

In general, our study provides a comprehensive mechanism that Cdk9 can promote epigenetic changes and modulate global and regional DNA methylation profiling of myoblast cells during differentiation.