Heart Centre, Children's Hospital of Chongqing Medical University, Chongqing, PR China.
Life Sci. 2010 Dec 18;87(23-26):707-14. doi: 10.1016/j.lfs.2010.10.009. Epub 2010 Oct 26.
Histone acetylation plays an important role in cardiogenesis, but the underlying mechanism is unclear. In this study, we investigated the relationship between histone hypo-acetylation and the expression of cardiac-specific genes to explore the underlying mechanisms.
Cardiac-specific genes that physically interacted with p300 protein in mouse hearts were analyzed using chromatin immunoprecipitation (ChIP) assays. The cultured mouse neonatal cardiac myocytes were treated with curcumin with different concentrations and durations. The changes of histone acetyltransferase (HAT) activities, histone acetylation, cardiac-specific genes expression, and structure of chromatin were assessed by ELISA, Western blotting, quantitative RT-PCR, and ChIP assays, respectively.
Results from the ChIP assay showed that GATA4, Nkx2.5, and Mef2c physically interacted with p300 protein. After treatment with 30 μM curcumin for 24h, the HAT activities of cardiac myocytes were inhibited significantly. And the acetylation of whole histone H3 was reduced by 0.3983-fold compared to control groups (P<0.05). Accordingly, the expression of cardiac-specific genes, GATA4, Nkx2.5, and Mef2c, were significantly down-regulated. Acetylation of histone H3 bound with promoter regions of these genes was significantly reduced.
p300 interacts with cardiac-specific genes, GATA4, Nkx2.5 and Mef2c, and inhibition of p300-HAT by curcumin down-regulates their expression through the inhibition of histone H3 acetylation in the promoter regions. This finding indicates that p300-HAT mediated histone H3 acetylation plays an important role in the regulation of cardiac gene expression, which is a novel mechanism of epigenetic regulation in the heart during the development and in case of some congenital heart diseases.
组蛋白乙酰化在心脏发生中起着重要作用，但具体机制尚不清楚。本研究旨在探讨组蛋白低乙酰化与心脏特异性基因表达之间的关系，以探索其潜在机制。
采用染色质免疫沉淀（ChIP）实验分析与小鼠心脏中 p300 蛋白相互作用的心脏特异性基因。用不同浓度和时间的姜黄素处理原代培养的新生鼠心肌细胞。通过 ELISA、Western blot、定量 RT-PCR 和 ChIP 实验分别评估组蛋白乙酰转移酶（HAT）活性、组蛋白乙酰化、心脏特异性基因表达和染色质结构的变化。
ChIP 实验结果表明，GATA4、Nkx2.5 和 Mef2c 与 p300 蛋白相互作用。用 30μM 姜黄素处理 24 小时后，心肌细胞的 HAT 活性显著抑制。与对照组相比，整个组蛋白 H3 的乙酰化降低了 0.3983 倍（P<0.05）。相应地，心脏特异性基因 GATA4、Nkx2.5 和 Mef2c 的表达显著下调。这些基因启动子区域结合的组蛋白 H3 乙酰化明显减少。
p300 与心脏特异性基因 GATA4、Nkx2.5 和 Mef2c 相互作用，姜黄素抑制 p300-HAT 通过抑制启动子区域的组蛋白 H3 乙酰化下调其表达。这一发现表明，p300-HAT 介导的组蛋白 H3 乙酰化在心脏基因表达的调控中起着重要作用，这是心脏发育和某些先天性心脏病中表观遗传调控的一种新机制。
