Histone modifications interact with DNA methylation at the GATA4 promoter during differentiation of mesenchymal stem cells into cardiomyocyte-like cells.

Abstract

A previous study of ours confirmed that Islet-1 specifically induces differentiation of MSCs into cardiomyocytes, and that one of the mechanisms underlying that process is regulation of histone acetylation. Here, we further explore the mechanism of MSC differentiation into cardiomyocytes from the perspective of interactions between epigenetic modifications. We used lentiviral vectors to overexpress Islet-1 in MSCs, and ChIP-qPCR, MSP and BSP were performed to detect levels of histone acetylation/methylation and DNA methylation in the GATA4 and Nkx2.5 promoters. To further explore relationships between these epigenetic modifications, we used 5-aza or TSA to interfere with DNA methylation and histone acetylation, respectively, and detected effects on the other two modifications. Histone acetylation level increased and its methylation level decreased at GATA4 and Nkx2.5 promoters; DNA methylation level was reduced at the GATA4 promoter but did not change at the Nkx2.5 promoter. Furthermore, 5-aza increased histone acetylation level and reduced its methylation level at the GATA4 promoter but had no effect on the Nkx2.5 promoter; TSA reduced histone methylation and DNA methylation levels at the GATA4 promoter, but it only reduced histone methylation level at the Nkx2.5 promoter. Histone acetylation/methylation and DNA methylation were both involved in regulating GATA4 expression, but Nkx2.5 expression was not regulated by DNA methylation. These three modifications had high correlation with each other during regulation of GATA4 and produced a regulation loop at the GATA4 promoter.