Annexin A7 is required for ESCRT III-mediated plasma membrane repair

Abstract

The plasma membrane of eukaryotic cells forms the essential barrier to the extracellular environment, and thus plasma membrane disruptions pose a fatal threat to cells. Here, using invasive breast cancer cells we show that the Ca 2+ - and phospholipid-binding protein annexin A7 is part of the plasma membrane repair response by enabling assembly of the endosomal sorting complex required for transport (ESCRT) III. Following injury to the plasma membrane and Ca 2+ flux into the cytoplasm, annexin A7 forms a complex with apoptosis linked gene-2 (ALG-2) to facilitate proper recruitment and binding of ALG-2 and ALG-2-interacting protein X (ALIX) to the damaged membrane. ALG-2 and ALIX assemble the ESCRT III complex, which helps excise and shed the damaged portion of the plasma membrane during wound healing. Our results reveal a novel function of annexin A7 – enabling plasma membrane repair by regulating ESCRT III-mediated shedding of injured plasma membrane.