Key Laboratory of Regenerative Medicine of Ministry of Education, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Institute of Aging and Regenerative Medicine, Jinan University, Guangzhou 510632, China.
Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Bone and Soft Tissue Tumor, Peking University Cancer Hospital and Institute, Beijing 100142, China.
J Mol Cell Biol. 2022 Jan 29;13(12):853-863. doi: 10.1093/jmcb/mjab059.
The biogenesis of autophagosomes provides the basis for macroautophagy to capture and degrade intracellular cargoes. Binding of the autophagy-related protein ATG8/LC3 to autophagic membranes is essential to autophagosome formation, which involves the specific and dynamic processing of ATG8/LC3 by cysteine protease ATG4. However, to date, the mechanism whereby ATG4 is recruited to the membranes, the interaction of ATG4 and ATG8/LC3 on the membranes, and its role in the growth of phagophore are not completely understood. Here, we used fluorescence recovery after photobleaching to monitor the turnover of GFP-tagged ATG4B and LC3B in living animal cells. The data show that ATG4B localizes to early autophagic membranes in an LC3B-dependent manner. During autophagy, ATG4B and LC3B undergo rapid cytosol/isolation membrane exchange but not at the cytosol/completed autophagosome. In addition, ATG4B activity controls the efficiency of autophagosome formation by impacting the membrane binding/dissociation of LC3B. These data suggest that ATG4 and LC3 play interdependent roles in the formation of autophagosomes.
自噬体的生物发生为巨自噬提供了捕获和降解细胞内货物的基础。自噬相关蛋白 ATG8/LC3 与自噬膜的结合对于自噬体的形成至关重要，这涉及到半胱氨酸蛋白酶 ATG4 对 ATG8/LC3 的特异性和动态加工。然而，迄今为止，ATG4 如何被招募到膜上、ATG4 和 ATG8/LC3 在膜上的相互作用及其在吞噬体生长中的作用尚不完全清楚。在这里，我们使用光漂白后荧光恢复来监测活细胞中 GFP 标记的 ATG4B 和 LC3B 的周转。数据表明，ATG4B 以 LC3B 依赖性的方式定位于早期自噬膜上。在自噬过程中，ATG4B 和 LC3B 经历快速的细胞质/隔离膜交换，但不在细胞质/完成的自噬体中。此外，ATG4B 的活性通过影响 LC3B 的膜结合/解离来控制自噬体形成的效率。这些数据表明，ATG4 和 LC3 在自噬体的形成中发挥相互依赖的作用。
