1. Connexin43 promotes exocytosis of damaged lysosomes through actin remodelling.
- Author
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Domingues, Neuza, Catarino, Steve, Cristóvão, Beatriz, Rodrigues, Lisa, Carvalho, Filomena A, Sarmento, Maria João, Zuzarte, Mónica, Almeida, Jani, Ribeiro-Rodrigues, Teresa, Correia-Rodrigues, Ânia, Fernandes, Fábio, Rodrigues-Santos, Paulo, Aasen, Trond, Santos, Nuno C, Korolchuk, Viktor I, Gonçalves, Teresa, Milosevic, Ira, Raimundo, Nuno, and Girão, Henrique
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CYTOSKELETON , *SALMONELLA diseases , *NIEMANN-Pick diseases , *EXOCYTOSIS , *CELL membranes , *LYSOSOMES , *DNA repair - Abstract
A robust and efficient cellular response to lysosomal membrane damage prevents leakage from the lysosome lumen into the cytoplasm. This response is understood to happen through either lysosomal membrane repair or lysophagy. Here we report exocytosis as a third response mechanism to lysosomal damage, which is further potentiated when membrane repair or lysosomal degradation mechanisms are impaired. We show that Connexin43 (Cx43), a protein canonically associated with gap junctions, is recruited from the plasma membrane to damaged lysosomes, promoting their secretion and accelerating cell recovery. The effects of Cx43 on lysosome exocytosis are mediated by a reorganization of the actin cytoskeleton that increases plasma membrane fluidity and decreases cell stiffness. Furthermore, we demonstrate that Cx43 interacts with the actin nucleator Arp2, the activity of which was shown to be necessary for Cx43-mediated actin rearrangement and lysosomal exocytosis following damage. These results define a novel mechanism of lysosomal quality control whereby Cx43-mediated actin remodelling potentiates the secretion of damaged lysosomes. Synopsis: Damaged lysosomes are marked for either membrane repair or removal by lysophagy. This report describes a third pathway, Connexin43-mediated lysosome exocytosis, that is also able to restore cell homeostasis. Lysosomal exocytosis upon injury is enhanced by inhibiting either lysophagy or lysosomal membrane repair. Connexin43 (Cx43) at the plasma membrane is recruited to Galectin3-positive damaged lysosomes via AP2-dependent endocytosis. Exocytosis of damaged lysosomes is potentiated by Cx43 through an Arp2-mediated remodelling of the actin cytoskeleton. Cx43-mediated lysosome exocytosis is relevant in pathological conditions such as Salmonella infection or the lysosomal storage disorder Niemann-Pick disease. Damaged lysosomes can be expelled from the cell in a Connexin43-dependent manner. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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