Lamp2介导脂噬双重调控信号参与PBC高脂血症的机制研究

PBC合并高脂血症患者中纠正其脂代谢紊乱可显著改善临床症状，在PBC发病进程中脂代谢调控意义重大。新近研究发现，溶酶体依赖的自噬脂解可对脂滴进行内化、包裹和降解，是脂解的重要方式，但机制不清。本课题组发现：PBC患者肝细胞Lamp2表达及分布异常，自噬障碍；血清Lamp2水平与胆固醇、甘油三酯水平成正相关；Lamp2敲除自噬异常，脂滴分解障碍。Lamp2自噬具有亚型特异性，脂滴蛋白Plin5可被Lamp2A介导的CMA所降解。因此，我们认为Lamp2通过大自噬和CMA自噬双重信号调控了脂滴的自噬脂解，其A、B亚型扮演了协同作用。本课题拟以脂滴自噬脂解为切入点，利用分子生物学、活细胞运输、超微结构分析、免疫共沉淀等方法，结合肝细胞Lamp2亚型特异性敲除的模式动物和病理标本验证，探讨Lamp2对脂滴自噬脂解的调控作用及机制，为深入理解PBC病理过程、发现治疗新靶点提供理论依据和实验基础。

Correction of lipid metabolism disorders in PBC patients with hyperlipidemia has good clinical efficacy, so it is of great significance to discuss the regulation of lipid metabolism in PBC. Recent studies have found that lysosome dependent lipophagy can directly internalize, encapsulate, and degrade lipid droplets. It is an important way for fat lipolysis, but the mechanism is unclear. In the previous study, we found abnormal expression and distribution of Lamp2 in liver cells and autophagy disorders in PBC patients. In addition, serum Lamp2 levels were positively correlated with cholesterol and triglyceride levels. Lamp2 knockout leads to autophagy abnormality and lipid disaggregation. Furthermore, Lamp2 autophagy has subtype specificity, and lipid droplet degradation regulation protein Plin5 can be degraded by Lamp2A mediated CMA. Therefore, we hypothesize that Lamp2 regulates lipophagy of lipid droplets through both macroautophagy and CMA autophagy, and the A and B subtypes of Lamp2 play a synergistic role. In this study, we are going to explore the regulatory mechanism of lipophagy mediated by Lamp2 using molecular biology, live cell transportation, ultrastructure analysis, and co-immunoprecipitation methods combined with model animals that are liver-specific conditional knockout for Lamp2 subtypes.. This study may provide both theoretical and experimental basis for understanding PBC pathological process and finding new target point for treatment.