靶向Atg8家族的自噬抑制性短肽的作用机制研究

Autophagy is an evolutionarily conserved degradation systems ubiquitously found in eukaryotes, playing important roles in maintaining cellular homeostasis and responding to stress conditions. Dysregulation of autophagy is closely related to human diseases such as neurodegenerative diseases, immune disorders, metabolic diseases and cancers. Therefore, precisely activating or inhibiting autophagy spatial-temporally might be a potential way to treat these diseases. In autophagy, Atg8 family members are involved in multiple processes, making them potential targeting sites of manipulating autophagy. However, the high sequence similarity and potential dosage compensation effect among different members make the canonical genetic methods such as knockdown or knockout become difficult. Developing Atg8-targeting inhibitors might be a solution. This proposal is based on our previous discovery of inhibitory peptides found in giant Ankyrins. We plan to use chemical biology approach to further expand the current pool of LIR-based Atg8-targeting inhibitory peptides, in order to meet various needs such as LC3 subfamily specific targeting, cell penetration, higher affinities, etc. We hope that the outcome of this proposal will provide more effective tools for deeper investigation of autophagy, as well as help the development of methods of treating autophagy-related diseases.

细胞自噬是真核生物中广泛存在的一种进化上保守的降解系统，对维持细胞稳态和应对外界刺激有重要作用 。自噬的异常与神经退行性疾病、免疫疾病、代谢紊乱疾病和癌症等密切相关。因此，在特定的时间和空间精准地激活或抑制自噬有望成为上述等多种疾病的一种潜在治疗方法。在自噬中，Atg8家族蛋白参与了多个步骤，是自噬调控的一个潜在靶点。然而Atg8家族蛋白成员间的高度相似性以及潜在的剂量补偿效应使得目前传统的遗传学手段（如敲低、敲除等）变得困难。靶向Atg8的抑制剂成为一个解决方案。本项目计划在之前从巨型锚蛋白中鉴定出的自噬抑制性多肽的基础上，利用化学生物学的方法进一步扩充基于LIR的Atg8自噬抑制短肽库，以满足如特异性靶向LC3亚家族、可穿透细胞膜、更强结合力等要求。研究成果将为自噬领域的深入研究提供有效的工具，并为未来治疗细胞自噬相关疾病的药物设计开发提供前期的积累。

细胞自噬是真核生物中广泛存在的一种进化上保守的降解系统，对维持细胞稳态和应对外界刺激有重要作用。本项目以Atg8家族蛋白为靶点，开发出自噬抑制性多肽，并阐明其抑制的分子机制。一方面，我们在前期研究的基础上，发现FAM134B上同样存在着一段序列可能结合Atg8家族蛋白。我们发现，FAM134B结合GABARAP亚家族比LC3亚家族更强。我们进一步解析了FAM134B-GABARAP复合物的晶体结构，并证明了FAM134B利用其LIR核心和C-末端的α-螺旋与GABARAP结合。该结构还使我们能够确定了结合选择性的结构决定因素。这部分的工作发表于FEBS Open Bio期刊中。另一方面，我们以前期从巨型锚蛋白中发现的LIR短肽为工具，发现了GABARAP在神经系统中可以通过与A型GABA受体的γ亚基直接相互作用，从而促进其细胞膜转运，此项工作发表于Nature Communications期刊中。