分子伴侣介导的自噬调控perilipin2蛋白降解稳定动脉粥样硬化易损斑块的分子机制研究

Atherosclerotic plaque rupture and thrombosis are the main cause of acute coronary syndrome. Researchers have found that chaperone-mediated autophagy(CMA) is involved in regulation of lipophagy and lipid metabolism. However, it remains unclear what is the role and molecular mechanism of CMA in the vulnerability of atherosclerotic plaques. In our previous study, we found that macrophages with deficient CMA were more sensitive to become foam cells in exposure of ox-LDL, as well as the lipophagy was inhibited; Besides, LAMP-2a, the key protein in CMA, was significantly decreased in advanced atherosclerotic plaques of ApoE-/- mouse. Hereby, we hypothesize that CMA is involved in the progression of atherosclerotic plaque by regulation of macrophage lipophagy and lipid metabolism. In this project, we will generate a conditional knockout mouse to selectively block CMA in macrophages (LAMP-2afl/fl/LysM-Cre/ApoE−/−mouse) as well as mouse with over-expression of LAMP-2a by lentivirus transfection, and to study the effect of CMA on lipophagy, lipid metabolism and plaque stability both in vivo and in vitro. In addition, degradation of perilipin2 by CMA will also be studied to explore the mechanism of CMA in regulation of lipophagy.

动脉粥样硬化（AS）易损斑块的破裂及血栓形成是急性冠脉综合征的主要机制，斑块易损性的机制研究已成为国内外的热点。研究发现分子伴侣介导的自噬（CMA）参与调节脂噬和脂质代谢。然而，CMA在AS易损斑块中的作用及机制尚未明确。我们的前期结果发现：CMA功能缺陷的巨噬细胞更易出现脂质蓄积，并且细胞脂噬过程受阻；小鼠晚期斑块中CMA关键蛋白LAMP-2a明显降低。我们提出CMA参与了斑块巨噬细胞脂噬过程和脂质代谢，进而影响斑块的稳定性，其中CMA对脂滴包被蛋白perilipin2蛋白的分解调控至关重要。我们拟通过构建巨噬细胞LAMP-2afl/fl/LysM-Cre/ApoE−/−基因敲除小鼠和过表达LAMP-2a基因分别抑制和促进小鼠CMA水平，从体内和体外研究CMA对小鼠斑块脂噬水平、脂质沉积和斑块稳定性的影响以及perilipin2蛋白表达水平，进而探明CMA影响脂噬和脂质代谢的分子机制。

炎症和脂质代谢是动脉粥样硬化（AS）发病机制的两个核心事件。深入研究AS过程中两者的调控机制意义重大。近年来，分子伴侣介导的自噬（CMA）参与了衰老、免疫和神经退行性病变等病理生理过程。但CMA在AS中的作用尚不清楚。我们在本研究中首次探索了CMA与AS关系。我们发现斑块中的巨噬细胞承载了CMA功能；在斑块进展过程中，CMA功能逐渐不足；且通过构建LAMP-2A敲基因小鼠，我们发现CMA缺陷促进了斑块进展。进一步，我们发现CMA不足引起巨噬细胞泡沫化增加及NLRP3炎性小体活化。在机制上，CMA缺陷导致溶酶体酸性水解酶（LAL）减少，脂质分解代谢障碍；同时，NLRP3蛋白分解受阻，NLRP3炎性小体过度活化。上调CMA功能可能会从调控脂质和减轻炎症两个方面治疗动脉粥样硬化、肥胖、代谢紊乱综合征等慢性疾病。