Liu Zhiqiang, Li Tao, Liu Yinan, Jia Zhuqing, Li Yanming, Zhang Chenguang, Chen Ping, Ma Kangtao, Affara Nabeel, Zhou Chunyan
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, 38 Xue Yuan Road, Hai Dian District, Beijing, 100191, China.
Biochim Biophys Acta. 2009 Feb;1793(2):300-11. doi: 10.1016/j.bbamcr.2008.08.013. Epub 2008 Sep 11.
The cardiac transcription factor NKX2.5 plays a crucial role in cardiomyogenesis, but its mechanism of regulation is still unclear. Recently, epigenetic regulation has become increasingly recognized as important in differentiation and development. In this study, we used P19CL6 cells to investigate the regulation of Nkx2.5 expression by methylation and acetylation during cardiomyocyte differentiation. During the early stage of differentiation, Nkx2.5 expression was upregulated, but the methylation status of the Nkx2.5 promoter did not undergo significant change; while the acetylation levels of histones H3 and H4 were increased, accompanied by a significant reduction in Hdac1 expression. Suppression of Hdac1 activity stimulated cardiac differentiation accompanied by increased expression of cardiac-specific genes and cell cycle arrest. Overexpression of Hdac1 inhibited cardiomyocyte formation and downregulated the expressions of Gata4 and Nkx2.5. Mimicking induction of the WNT pathway inhibited Hdac1 expression with upregulated Nkx2.5 expression. WNT3a and WNT3 downregulated the expression of Hdac1, contrary to the effect of SFRP2 and GSK3beta. Cotransfection of beta-catenin and Lef1 significantly downregulated the expression of Hdac1. Our data suggest that WNT signaling pathway plays important roles in the regulation of Hdac1 during the early stage of cardiomyocyte differentiation and that the downregulation of Hdac1 promotes cardiac differentiation.
心脏转录因子NKX2.5在心肌生成过程中发挥着关键作用，但其调控机制仍不清楚。近来，表观遗传调控在分化和发育中的重要性日益得到认可。在本研究中，我们利用P19CL6细胞来研究心肌细胞分化过程中甲基化和乙酰化对Nkx2.5表达的调控。在分化早期，Nkx2.5表达上调，但Nkx2.5启动子的甲基化状态未发生显著变化；而组蛋白H3和H4的乙酰化水平升高，同时Hdac1表达显著降低。抑制Hdac1活性可刺激心脏分化，同时心脏特异性基因的表达增加且细胞周期停滞。过表达Hdac1可抑制心肌细胞形成，并下调Gata4和Nkx2.5的表达。模拟WNT信号通路的激活可抑制Hdac1表达，同时上调Nkx2.5表达。WNT3a和WNT3下调Hdac1的表达，这与SFRP2和GSK3β的作用相反。β-连环蛋白和Lef1共转染可显著下调Hdac1的表达。我们的数据表明，WNT信号通路在心肌细胞分化早期对Hdac1的调控中发挥重要作用，且Hdac1的下调可促进心脏分化。
