SMYD3调控内皮细胞衰老在血管功能紊乱中作用及表观机制研究

Vascular endothelial senescence plays a pivotal role in the development of cardiovascular diseases. Our previous results have demonstrated that the upregulation of histone methyltransferase SMYD3 was observed in atherosclerotic arteries of patients, which was accompanying with increase of senescent makers and senescence-associated secretory phenotype. The similar results were also observed in angiotensin II (Ang II)-induced vascular endothelial senescence. The events were reversed by SMYD3 knockdown strategy. However, the role and epigenetic mechanisms of SMYD3 in endothelial senescence and senescence-related cardiovascular diseases remain unclear. Herein, we propose the following hypothesis that SMYD3 promoted the development of vascular endothelial senescence and senescence-related cardiovascular disease through modulation the histone modification. In our follow-up study, we will elucidate that SMYD3 accelerated the development of endothelial senescence and senescence-associated cardiovascular diseases and underlying epigenetic mechanism. 1) Senescence of rat aortic endothelial cells induced by Ang II and senescent artery endothelial cells isolated from atherosclerotic arteries of patients and senescent makers, endothelial function, senescence-associated secretory phenotype were measured to demonstrated that SMYD3 accelerated endothelial senescence. Lentiviral SMYD3 overexpression or knockdown will be used. 2) To elucidate the role of SMYD3 in vascular dysfunction, vascular dysfunction was induced by Ang II in endothelium-specific SMYD3 knockout mice. Vascular function, vascular endothelial senescence, et al. in artery were compared by combining lentiviral-mediated SMYD3 overexpression/knockdown. 3) atherosclerosis was induced by high fat diet in ApoE-/- mice and the plaque size，fibrous cap stability, vascular endothelial senescence, inflammatory mediators in atherosclerotic vascular were measured. A positive correlation of SMYD3 expression with atherosclerosis and a key role of SMYD3 in high fat diet-induced atherosclerosis were identified by combining lentiviral-mediated SMYD3 overexpression/knockdown. 4) In above-mentioned cell and animal models by various molecular biology techniques, we further verify that the epigenetic mechanism is that SMYD3 strengthens NF-κB transcriptional activity, which enhances it’s binding to the senescent makers and SASP promoter and increases senescent makers and SASP transcription. These findings will shed lights on the mechanistic insights during development of senescence-related cardiovascular diseases and suggest that SMYD3 serves as a novel therapeutic target for treating senescence-related cardiovascular diseases..

血管内皮细胞（VECs）衰老是心血管疾病发病的关键。前期已发现动脉斑块中组蛋白甲基转移酶SMYD3上调并伴随衰老标记物和衰老分泌炎症表型增加；在血管紧张素II（Ang II）诱导VECs衰老中同样伴有SMYD3和衰老分泌炎症表型，沉默SMYD3可逆转其衰老及其表型。但SMYD3在VECs衰老及衰老相关心血管疾病中的作用和表观遗传机制仍不明确。据此提出“SMYD3调控组蛋白甲基化修饰增强其下游靶基因转录表达，促进VECs衰老及相关心血管疾病的发生发展”的假说。拟用体外VECs衰老和临床动脉粥样硬化样本、体内Ang II诱导小鼠血管衰老模型及高脂诱导ApoE-/-小鼠动脉粥样硬化模型，结合构建VECs特异性SMYD3-/-模式动物和慢病毒SMYD3沉默/过表达技术，阐明SMYD3促进VECs衰老加速血管功能紊乱作用，并明确SMYD3增强NF-κB转录的表观遗传机制，为心血管疾病的防治提供新靶点

血管内皮细胞（VECs）衰老是心血管疾病发病的关键。前期已发现动脉斑块中组蛋白甲基转移酶SMYD3上调并伴随衰老标记物和衰老分泌炎症表型增加；在血管紧张素II（Ang II）诱导VECs衰老中同样伴有SMYD3和衰老分泌炎症表型，沉默SMYD3可逆转其衰老及其表型。但SMYD3在VECs衰老及衰老相关心血管疾病中的作用和表观遗传机制仍不明确。据此提出“SMYD3调控组蛋白甲基化修饰增强其下游靶基因转录表达，促进VECs衰老及相关心血管疾病的发生发展”的假说。1）在体外我们利用Ang II 诱导VECs衰老模型，发现沉默或抑制SMYD3可逆转其衰老及其表型；2）体内用Ang II缓慢灌注诱导SMYD3-/-和WT小鼠血管衰老模型，发现SMYD3-/-小鼠和WT小鼠相比明显减轻血压的升高、血管重构、血管舒张功能等表型，并明显减少血管的衰老标记物和衰老分泌炎症表型；3）机制上利用ChIP-seq和RNA-seq阐明SMYD3直接结合在p21基因的启动子区，促进其转录，而进一步促进衰老表型，进一步的研究还发现SMYD3直接结合在内质网应激的膜蛋白PARP16的启动子区，促进其转录，而进一步促进内质网应激介导的细胞衰老。本项目明确了SMYD3促进VECs衰老加速血管功能紊乱作用，并明确SMYD3的表观调控机制，在在人的动脉粥样硬化和其它衰老相疾病模型上进一步确认，此调控机制是保守的，为心血管疾病的防治提供新靶点。