AUTHOR=Ebstrup Malene Laage , Sønder Stine Lauritzen , Fogde Ditte Louise , Heitmann Anne Sofie Busk , Dietrich Tiina Naumanen , Dias Catarina , Jäättelä Marja , Maeda Kenji , Nylandsted Jesper TITLE=Annexin A7 mediates lysosome repair independently of ESCRT-III JOURNAL=Frontiers in Cell and Developmental Biology VOLUME=11 YEAR=2024 URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2023.1211498 DOI=10.3389/fcell.2023.1211498 ISSN=2296-634X ABSTRACT=

Lysosomes are crucial organelles essential for various cellular processes, and any damage to them can severely compromise cell viability. This study uncovers a previously unrecognized function of the calcium- and phospholipid-binding protein Annexin A7 in lysosome repair, which operates independently of the Endosomal Sorting Complex Required for Transport (ESCRT) machinery. Our research reveals that Annexin A7 plays a role in repairing damaged lysosomes, different from its role in repairing the plasma membrane, where it facilitates repair through the recruitment of ESCRT-III components. Notably, our findings strongly suggest that Annexin A7, like the ESCRT machinery, is dispensable for membrane contact site formation within the newly discovered phosphoinositide-initiated membrane tethering and lipid transport (PITT) pathway. Instead, we speculate that Annexin A7 is recruited to damaged lysosomes and promotes repair through its membrane curvature and cross-linking capabilities. Our findings provide new insights into the diverse mechanisms underlying lysosomal membrane repair and highlight the multifunctional role of Annexin A7 in membrane repair.