Dynamic visualization of DNA methylation in cell cycle genes during iPSC cardiac differentiation.

BACKGROUND: Existing analyses with conventional assays have generated significant insights into static states of DNA methylation but were unable to visualize the dynamics of epigenetic regulation. MATERIALS & RESULTS: We utilized a genomic DNA methylation reporter (GMR) system carrying Snrpn minimal promoter and CpG regions of Cdk1 (Cyclin-dependent kinase 1) or Sox2 (SRY-Box Transcription Factor 2). Mouse Sox2 GMR iPSCs rapidly lost fluorescent reporter signal upon the induction of cardiac differentiation. Cdk1 GMR reporter signal was strong in undifferentiated iPSCs, and gradually decreased during cardiomyocyte differentiation. RT-qPCR and pyrosequencing demonstrated that the reduction of Sox2 and Cdk1 was regulated by hypermethylation of their promoters' CpG regions during cardiac differentiation. CONCLUSION: The GMR reporter system can be useful for monitoring real-time epigenetic DNA modification at single-cell resolution.