HO-1对血管内皮细胞应激性衰老的调控机制

Endothelial senescence is the onset of endothelial dysfunction and the main cause of several cardiovascular diseases like atherosclerosis. In our previous observations, up-regulation of heme oxygenase-1 (HO-1) prevented vascular endothelial dysfunction and protected the endothelial cells from stress-induced premature senescence. Expressions of HO-1 were up-regulated in senescent endothelial cells. Induction of HO-1 prevented stress-induced senescence, while silencing HO-1 gene exacerbated senescence in vascular endothelial cells. Based on these observations, the present study will focus on the mechanisms that HO-1 regulates cellular senescence. Since endothelial senescence is associated with oxidative stress, the effects of HO-1 on oxidative stress-induced telomere damage and DNA damage, and the effects of HO-1 on cellular metabolic dysfunction caused by mitochondrial dysfunction, will be investigated. In addition, since over-activation of mTOR signaling is a key mechanism leading to endothelial senescence, the effect of HO-1 on the mTOR signaling pathway, in particular the mTORC2-Akt pathway, will be studied. Moreover, the possible protective effect of HO-1 induction against endothelial senescence and dysfunction will be investigated in vivo in an ApoE-/- mice atherosclerosis model. The present study will pave the way to design selective pharmacological inducers of HO-1 as a potential therapeutic strategy for treating endothelial dysfunction in cardiovascular diseases.

血管内皮细胞应激性衰老可导致内皮功能障碍，进而引发动脉粥样硬化等血管性疾病。前期研究发现血红素加氧酶-1（HO-1）对内皮功能有显著的保护作用，并初步证实其对内皮应激性衰老有确切的调控作用：HO-1表达在衰老内皮细胞中反馈性上调；诱导HO-1改善、siRNA干扰HO-1加剧内皮衰老。本项目拟在此基础上深入研究HO-1对内皮应激性衰老的调控机制。有证据表明内皮应激性衰老与氧化应激及mTOR通路过度激活密切相关。本课题将从调节氧化应激、mTOR信号途径的角度深入研究HO-1的调控机制，探讨HO-1调节端粒、DNA氧化损伤的作用，以及调节线粒体功能、改善细胞能量代谢的作用；探讨HO-1对mTOR信号转导途径（特别是mTORC2）的调节影响。并将在ApoE-/-小鼠动脉粥样硬化模型上验证HO-1对内皮衰老的作用和机制，为将HO-1作为防治动脉粥样硬化等心脑血管疾病的潜在作用靶标提供充足的实验依据。

血管内皮细胞应激性衰老是导致内皮功能障碍、诱发动脉粥样硬化等血管性疾病的核心环节，从调节内皮应激性衰老的角度探讨心血管疾病的防治靶标是可行的新策略。HO-1作为机体最重要的内源性保护蛋白，在前期研究中表现出确切的内皮保护作用，可显著逆转高血压引起的内皮功能障碍。作为前期研究的深入和延伸，本课题立足于应激性衰老这一重要的内皮细胞功能障碍机制，探讨HO-1调控内皮细胞衰老的具体分子机制。本研究通过体内、体外实验，明确了HO-1通过调节NO的生成干预内皮应激性衰老进程，其调节机制包括：（1）通过与eNOS相互作用，促进eNOS与其上游激酶Akt的结合，从而增强eNOS Ser-1177位点磷酸化；（2）通过抗氧化机制，抑制氧化应激介导的eNOS解偶联。此外，从HO-1的上游调节分子mTORC2、SIRT6，下游效应分子STAT3的角度，进一步探讨了通过调节HO-1调控内皮衰老和炎症反应、动脉粥样硬化、心肌肥大等心血管疾病的可行性：（1）明确了内皮复制性衰老及应激性衰老中mTORC2通过mTORC2-Akt-GSK3β-C/EBPα-Nrf2-HO-1信号转导通路参与了对HO-1的调节；（2）揭示了HO-1的潜在上游调控酶III类组蛋白去乙酰化酶SIRT6通过抑制内皮粘附因子ICAM-1的表达，改善内皮炎症反应，进而阻遏动脉粥样硬化疾病进程；（3）揭示了HO-1的下游效应机制STAT3，受SIRT6、PKCzeta的调控，影响心肌肥大发生发展。本课题通过深入研究HO-1调节内皮应激性衰老的机制，为寻找与内皮衰老相关的心血管疾病防治的新靶点提供理论依据。