CSE/H2S通过KLF4调控内皮细胞自噬拮抗动脉粥样硬化

Endothelial autophagy plays an important role in maintaining the integrity of endothelial structure and function, which eliminates the impaired mitochondria in cells and enhances the anti-oxidative capacity of endothelial cells. H2S participate in the pathogenesis of cardiovascular system diseases by regulating autophagy. Our preliminary experiment showed that oxLDL could induce autophagy in endothelial cells; CSE/H2S upregulates oxLDL-induced autophagy in endothelial cells; CSE/H2S upregulates the protein expression and sulfhydration level of KLF4. Here come up with a hypothesis: CSE/H2S mediates endothelial autophagy via KLF4 to reduce atherosclerosis. In this study, we intend to investigate: the effect of endothelium-specific knockout CSE or H2S donor on atherosclerotic plaque and the change of endothelial autophagy; the effect of endothelium-specific knockout CSE or H2S donor on oxLDL induced human aortic endothelial cell (HAEC) autophagy and the possible regulatory effect of KLF4. In the end, we explore the sulfhydration site of KLF4 and the regulatory effect CSE/H2S on its transcriptional activity to support our hypothesis. This research elucidates a new autophagy mechanism of endothelial CSE/H2S system on endothelial protection function and a new protein modification mechanism regulating the activity of transcription factor KLF4.

内皮细胞自噬可以清除细胞内受损线粒体，增强内皮细胞应对氧化损伤的能力，对维持内皮结构和功能的完整性具有重要作用。H2S可通过调节自噬参与心血管系统疾病的发病。我们预实验发现，oxLDL能诱导内皮细胞自噬；CSE/H2S上调oxLDL诱导的内皮细胞自噬；CSE/H2S上调KLF4的蛋白表达与硫氢化修饰水平；据此提出假说：CSE/H2S可能通过KLF4调节内皮细胞自噬拮抗动脉粥样硬化。本研究拟观察内皮特异敲除CSE或H2S供体对动脉粥样硬化斑块形成的影响以及内皮细胞自噬的改变；内皮细胞敲除CSE或H2S供体对oxLDL刺激人主动脉内皮细胞（HAEC）细胞自噬的改变及KLF4可能的调控作用；探讨KLF4硫氢化及其位点以及CSE/H2S对其转录活性的调控来论证我们的假说。本项目阐明了内皮细胞内源性CSE/H2S系统内皮功能保护新的自噬机制，及其调控转录因子KLF4活性的蛋白修饰新机制。

血管内皮损伤是心血管系统疾病的始动因素，参与动脉粥样硬化、高血压等疾病的启动与进展，同时会影响多种器官的正常功能。H2S作为第三种气体信号分子，参与内皮细胞完整性及内皮功能稳态的调控，在动脉粥样硬化的发生发展中发挥重要作用。本项目旨在探究CSE/H2S调控内皮细胞功能拮抗动脉粥样硬化的作用及机制。研究发现外源性提供NaHS激活细胞自噬，减轻动脉粥样硬化；内皮内源性CSE缺失抑制内皮细胞自噬，加重动脉粥样硬化斑块进展；人主动脉内皮细胞实验证实H2S激活自噬，抑制脂质沉积，机制上可能通过调控KLF4达成。内皮细胞受损同样是急性肺损伤发病的重要机制，后续我们对内皮细胞焦亡在CSE/H2S减轻急性肺损伤中的作用进行了探究。结合内皮CSE特异性敲除小鼠进行实验，研究发现：CSE/H2S可抑制内皮细胞焦亡，减轻LPS诱导的急性肺损伤；内皮CSE/H2S通过调控SIRT1抑制内皮细胞焦亡；H2S通过上调SIRT1表达和硫氢化修饰水平增强其活性。