Beclin2卷曲螺旋结构域调控细胞自噬与CB1R降解的作用机制研究

1型大麻素受体（CB1R）信号异常活跃与肥胖和糖尿病等密切相关。近期发现Beclin1同源蛋白Beclin2参与自噬和CB1R等GPCR蛋白降解的调控，但具体的调控机制不明。本项目前期研究发现Beclin2通过卷曲螺旋域（CCD）与Atg14L或UVRAG结合，率先解析了Beclin2-Atg14L CCD复合物的晶体结构，并证实Beclin2 CCD突变体可抑制GPCR降解。因此本团队推测“Beclin2与Atg14L或UVRAG相互作用并调控自噬和CB1R降解”。本项目拟在明确Beclin2-Atg14L/UVRAG相互作用机理的基础上，考察其对自噬和CB1R降解的调控机制；同时设计能特异性靶向Beclin2并增强相互作用的订书肽，检测其对自噬和CB1R降解的影响。本研究将有助于揭示Beclin2介导的细胞自噬和CB1R降解的作用机制，深化认识其在代谢性疾病调控中的分子功能。

Aberrant cannabinoid receptor 1 (CB1R) signaling is associated with obesity and diabetes. Beclin2 is a recently discovered novel ortholog of mammalian Beclin1. In addition to fulfilling similar functions as Beclin1 in autophagy regulation, Beclin2 also plays a unique role in lysosomal degradation of GPCR proteins like CB1R, and is implicated in metabolic disorders, but the molecular mechanism remains poorly understood. Our previous studies show that Beclin2 directly interacts with Atg14L and UVRAG through its coiled-coil domain (CCD), and the crystal structure of Beclin2-Atg14L CCD complex was determined. Beclin2 CCD mutant that weaken these interactions could suppress GPCR degradation. Thus, we proposed that “through its CCD, Beclin2 interacts with Atg14L or UVRAG to modulate autophagy and CB1R degradation”. In this study, we aim to characterize the molecular determinants of Beclin2- Atg14L/UVRAG interactions, and to explore how these interactions involved in autophagy and CB1R degradation regulation; we also plan to develop stapled peptides that can specifically target to Beclin2 CCD, strengthen interactions, and to determine their effects on autophagy and CB1R degradation. Our findings will not only provide insights on molecular mechanisms underlying Beclin2-mediated autophagy and CB1R degradation signalling, they will also expand our knowledge on the functional role of Beclin2 in metabolic disease.