人参皂苷Rd在心肌细胞肥大过程中对P300的autoacetylation下调的表观遗传调控机制研究

Histone acetyltransferase P300 is an important transcription activating factor in cardiac myocytes, and high expression of P300 will cause myocardial hypertrophy.It has been reported that calcium channel blockers can inhibit P300, which further delayes acute myocardial hypertrophy. Ginsenoside Rd, as a new calcium channel blocker, has a unique effect on cardiovascular disease. We have demonstrated that ginsenoside Rd significantly down regulated P300 autoacetylation and histone H3 acetylation in cardiac myocytes. However, it has not been reported that ginsenoside Rd can decrease P300 autoacetylation, which is of great influence on the activity of P300 itself. In this project, we will confirm the essence that the effect of ginsenoside Rd on P300 autoacetylation down-regulation based on the histone acetyltransferase activity assay (HAT assay), and study the epigenetic regulation mechanism of cardiomyocyte hypertrophy therapy by ginsenoside Rd via P300 inhibition. We will prove that ginsenoside Rd down regulates histone H3 acetylation by inhibiting P300 activity, which in turn regulates the key genes expression and and attenuates myocardial hypertrophy. Our research will promote the wide application of ginsenoside Rd in cardiovascular disease.

组蛋白乙酰转移酶P300是心肌细胞中重要的转录激活因子，它的高表达可直接导致心肌细胞肥大。已有文献报道，钙通道阻滞剂可以抑制P300并延缓心肌肥厚的病理进程。人参皂苷Rd是一种新型钙通道阻滞剂，我们率先证实，人参皂苷Rd能够下调心肌细胞中P300的自乙酰化（autoacetylation）及组蛋白H3的乙酰化。P300的autoacetylation对其转录激活作用具有重大影响，目前尚无人参皂苷Rd下调P300的autoacetylation的报道。本项目将基于组蛋白乙酰转移酶活性实验（HAT assay）确证人参皂苷Rd下调P300的autoacetylation的作用机理，并深入研究人参皂苷Rd介导P300治疗心肌细胞肥大的表观遗传调控机制，以证明“人参皂苷Rd通过抑制P300活性，降低组蛋白H3乙酰化，调节关键蛋白的表达，从而缓解心肌细胞肥大”，推动人参皂苷Rd在心管疾病中的应用。

组蛋白乙酰转移酶P300是心肌细胞中重要的转录激活因子，它的高表达可直接导致心肌细.胞肥大。P300抑制剂可以延缓心肌肥厚的病理进程。人参皂苷Rd是一种新型钙通道阻滞剂具有潜在的心血管保护作用。本项目对人参皂苷Rd干预前后的小鼠心肌细胞进行了定量蛋白质组和乙酰化修饰谱分析，结果显示组蛋白H3K9、H3K18及P300活性结构域（aa1284–1673）的多个赖氨酸位点乙酰化修饰水平降低。利用蛋白质免疫沉淀、体外HAT assay等生化实验证明，人参皂苷Rd能够通过下调心肌细胞中P300的自乙酰化（autoacetylation）抑制P300的乙酰转移酶活性，并进一步降低组蛋白H3K9、H3K18位点的乙酰化水平。在血管紧张素II诱导的心肌细胞肥大及TAC法造成的心肌损伤模型中，人参皂苷Rd通过抑制P300和组蛋白H3K9ac乙酰化能够有效缓解心肌细胞损伤的症状。证明“人参皂苷Rd通过抑制P300活性，降低组蛋白H3乙酰化，调节关键蛋白的表达，从而缓解心肌细胞肥大”，为人参皂苷Rd治疗心管疾病提供了理论基础。同时，本项目从人参药材中纯化了人参糖蛋白和人参外泌体，并对他们的心脏保护作用进行了研究，实验证明人参中的非皂苷类活性物质可以通过通过抗氧化应激、降低线粒体膜电位、抑制细胞凋亡等方式，抑制DOX造成的心肌损伤，具有重要的研究价值。