Zhang Rui, Zhang Xin, Bai Hua, Cheng Qiuyu, Yao Xia, Li Shi, Torraca Vincenzo, Yan Chaojun, Dong Xueying, Miao Siyi, Hu Xueyuan, Yu Yeping, Wu Yueyan, Tan Hongfei, Chen Xin, Liu Shicheng, Lyu Hao, Xiao Shuai, Guo Dong, Zhang Qi, Chen Xing-Zhen, Song Zhiyin, Zhou Cefan, Tang Jingfeng
National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, China.
Department of Infectious Diseases, School of Immunology and Microbial Sciences, King's College London, London, UK.
Nat Commun. 2025 Jul 1;16(1):5826. doi: 10.1038/s41467-025-60887-y.
Autophagy classically functions to protect cells and organisms during stressful conditions by catabolizing intracellular components to maintain energy homeostasis. Lysosome-autophagosome fusion is a critical step in emptying degraded unwanted contents. However, the mechanism of autophagosome fusion with lysosomes is still not fully understood. Here, we report that DNA Damage-Regulated Autophagy Modulator 1 (DRAM1) interacts with Vesicle Associated Membrane Protein 8 (VAMP8) to mediate the fusion of autophagosomes with lysosomes. This DRAM1-VAMP8 interaction is enhanced upon stimulation of autophagy. However, DRAM1 preferentially mediates the fusion between autophagosomes and lysosomes by enhancing the assembly of the STX17-SNAP29-VAMP8 complex. Moreover, we reveal that DRAM1 specifically promotes the stability of lysosomal VAMP8 via inhibiting VAMP8 degradation by CHIP mediating ubiquitination. We also identify that DRAM1 inhibits the ubiquitination of VAMP8 at Lys 68,72, and 75 via competitively binding with CHIP. Furthermore, we demonstrate that DRAM1 promotes the extravasation of Hepatocellular Carcinoma (HCC) cells, and this process relies on enhanced autophagosome degradation. Our study reveals a mechanism for regulating autolysosome formation by DRAM1-VAMP8 association and suggests a potential strategy to inhibit the extravasation of HCC.
自噬的经典功能是在应激条件下通过分解细胞内成分来维持能量稳态,从而保护细胞和生物体。溶酶体-自噬体融合是清除降解的不需要内容物的关键步骤。然而,自噬体与溶酶体融合的机制仍未完全了解。在此,我们报告DNA损伤调节自噬调节剂1(DRAM1)与囊泡相关膜蛋白8(VAMP8)相互作用,介导自噬体与溶酶体的融合。这种DRAM1-VAMP8相互作用在自噬刺激后增强。然而,DRAM1通过增强STX17-SNAP29-VAMP8复合物的组装,优先介导自噬体与溶酶体之间的融合。此外,我们发现DRAM1通过抑制CHIP介导的泛素化导致的VAMP8降解,特异性地促进溶酶体VAMP8的稳定性。我们还确定DRAM1通过与CHIP竞争性结合,抑制VAMP8在赖氨酸68、72和75处的泛素化。此外,我们证明DRAM1促进肝癌(HCC)细胞的外渗,并且这个过程依赖于增强的自噬体降解。我们的研究揭示了一种通过DRAM1-VAMP8结合调节自噬溶酶体形成的机制,并提出了一种抑制HCC外渗的潜在策略。