Ubiquitin profiling of lysophagy identifies actin stabilizer CNN2 as a target of VCP/p97 and uncovers a link to HSPB1
B Kravić, T Bionda, A Siebert, P Gahlot, S Levantovsky… - Molecular cell, 2022 - cell.com
B Kravić, T Bionda, A Siebert, P Gahlot, S Levantovsky, C Behrends, H Meyer
Molecular cell, 2022•cell.comLysosomal membrane permeabilization (LMP) is an underlying feature of diverse conditions
including neurodegeneration. Cells respond by extensive ubiquitylation of membrane-
associated proteins for clearance of the organelle through lysophagy that is facilitated by the
ubiquitin-directed AAA-ATPase VCP/p97. Here, we assessed the ubiquitylated proteome
upon acute LMP and uncovered a large diversity of targets and lysophagy regulators. They
include calponin-2 (CNN2) that, along with the Arp2/3 complex, translocates to damaged …
including neurodegeneration. Cells respond by extensive ubiquitylation of membrane-
associated proteins for clearance of the organelle through lysophagy that is facilitated by the
ubiquitin-directed AAA-ATPase VCP/p97. Here, we assessed the ubiquitylated proteome
upon acute LMP and uncovered a large diversity of targets and lysophagy regulators. They
include calponin-2 (CNN2) that, along with the Arp2/3 complex, translocates to damaged …
Summary
Lysosomal membrane permeabilization (LMP) is an underlying feature of diverse conditions including neurodegeneration. Cells respond by extensive ubiquitylation of membrane-associated proteins for clearance of the organelle through lysophagy that is facilitated by the ubiquitin-directed AAA-ATPase VCP/p97. Here, we assessed the ubiquitylated proteome upon acute LMP and uncovered a large diversity of targets and lysophagy regulators. They include calponin-2 (CNN2) that, along with the Arp2/3 complex, translocates to damaged lysosomes and regulates actin filaments to drive phagophore formation. Importantly, CNN2 needs to be ubiquitylated during the process and removed by VCP/p97 for efficient lysophagy. Moreover, we identified the small heat shock protein HSPB1 that assists VCP/p97 in the extraction of CNN2 and show that other membrane regulators including SNAREs, PICALM, AGFG1, and ARL8B are ubiquitylated during lysophagy. Our data reveal a framework of how ubiquitylation and two effectors, VCP/p97 and HSPB1, cooperate to protect cells from the deleterious effects of LMP.
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