Mitochondrial-derived vesicles drive budding-type fission of damaged lysosomes

Abstract

Lysosomes are central degradative organelles essential for cellular homeostasis, yet the mechanisms that maintain their integrity and function under stress remain incompletely understood. Here we identify a previously unrecognized lysosomal renewal process, termed budding-type fission (B-fission), which restores lysosomal function during hypoxia–reoxygenation stress. During B-fission, damaged lysosomes generate membrane buds that undergo scission to form small, fully functional lysosomes, independently of autophagic lysosome reformation. Mechanistically, mitochondrial-derived vesicles (MDVs) deliver the fission adaptor MFF to lysosomes, where MFF recruits the dynamin-related GTPase DRP1 to drive membrane scission. MIRO2 promotes the formation of MFF+ MDVs through direct interaction with MFF, while the lysosomal membrane protein ITM2C binds MIRO2 to tether and guide MFF+ MDVs to lysosomes, enabling efficient MFF delivery and subsequent B-fission. Notably, AMPK activation by 991 or metformin promotes MFF-dependent lysosomal B-fission under normoxic conditions, whereas AMPK inhibition by dorsomorphin suppresses B-fission during hypoxia–reoxygenation. This stress-responsive ITM2C–MIRO2–MFF–DRP1 axis co-opts the mitochondrial division machinery to drive lysosomal fission from damaged lysosomes, thereby enabling the undamaged components to reorganize into daughter lysosomes and promote lysosomal renewal. Thus, our findings uncover a fundamental mode of lysosomal renewal and reveal an unexpected role for MDV-mediated mitochondria–lysosome communication in mediating lysosomal quality control during ischaemia–reperfusion and related stresses. Luo et al. describe a budding type of lysosome fission linked to delivery of MFF from mitochondrial-derived vesicles to lysosomes. MFF recruits DRP1 for membrane scission. This axis restores lysosome function during hypoxia–reoxygenation stress.