Plasma Membrane Repair Is Mediated by Ca2+-Regulated Exocytosis of Lysosomes

Plasma membrane wounds are repaired by a mechanism involving Ca2+-regulated exocytosis. Elevation in intracellular [Ca2+] triggers fusion of lysosomes with the plasma membrane, a process regulated by the lysosomal synaptotagmin isoform Syt VII. Here, we show that Ca2+-regulated exocytosis of lysosomes is required for the repair of plasma membrane disruptions. Lysosomal exocytosis and membrane resealing are inhibited by the recombinant Syt VII C2A domain or anti-Syt VII C2A antibodies, or by antibodies against the cytosolic domain of Lamp-1, which specifically aggregate lysosomes. We further demonstrate that lysosomal exocytosis mediates the resealing of primary skin fibroblasts wounded during the contraction of collagen matrices. These findings reveal a fundamental, novel role for lysosomes: as Ca2+-regulated exocytic compartments responsible for plasma membrane repair.