Macroautophagy is a bulk degradation system in which double membrane-bound structures called autophagosomes to deliver cytosolic materials to lysosomes. Autophagy promotes cellular homeostasis by selectively recognizing and sequestering specific targets, such as damaged organelles, protein aggregates, and invading bacteria, termed selective autophagy. We previously reported a type of selective autophagy, lysophagy, which helps clear damaged lysosomes. Damaged lysosomes become ubiquitinated and recruit autophagic machinery. Proteomic studies using transfection reagent-coated beads and further evaluations reveal that a CUL4A-DDB1-WDFY1 E3 ubiquitin ligase complex is essential to initiate lysophagy and clear damaged lysosomes. Moreover, we show that LAMP2 is ubiquitinated by the CUL4A E3 ligase complex as a substrate on damaged lysosomes. These results reveal how cells selectively tag damaged lysosomes to initiate autophagy for the clearance of lysosomes.

巨自噬是一种整体降解系统，其中称为自噬体的双膜结合结构将细胞溶质物质输送到溶酶体。自噬通过选择性识别和隔离特定目标（例如受损细胞器、蛋白质聚集体和入侵细菌）来促进细胞稳态，称为选择性自噬。我们之前报道了一种选择性自噬，溶酶体，它有助于清除受损的溶酶体。受损的溶酶体变得泛素化并募集自噬机制。使用转染试剂包被的珠子进行的蛋白质组学研究和进一步的评估表明，CUL4A-DDB1-WDFY1 E3 泛素连接酶复合物对于启动溶酶体和清除受损溶酶体至关重要。此外，我们表明 LAMP2 被 CUL4A E3 连接酶复合物泛素化，作为受损溶酶体的底物。