title: Perforin activates clathrin- and dynamin-dependent endocytosis, which is required for plasma membrane repair and delivery of granzyme B for granzyme-mediated apoptosis.
abstract: Cytotoxic T lymphocytes and natural killer cells destroy target cells via the polarized exocytosis of lytic effector proteins, perforin and granzymes, into the immunologic synapse. How these molecules enter target cells is not fully understood. It is debated whether granzymes enter via perforin pores formed at the plasma membrane or whether perforin and granzymes are first endocytosed and granzymes are then released from endosomes into the cytoplasm. We previously showed that perforin disruption of the plasma membrane induces a transient Ca(2+) flux into the target cell that triggers a wounded membrane repair response in which lysosomes and endosomes donate their membranes to reseal the damaged membrane. Here we show that perforin activates clathrin- and dynamin-dependent endocytosis, which removes perforin and granzymes from the plasma membrane to early endosomes, preserving outer membrane integrity. Inhibiting clathrin- or dynamin-dependent endocytosis shifts death by perforin and granzyme B from apoptosis to necrosis. Thus by activating endocytosis to preserve membrane integrity, perforin facilitates granzyme uptake and avoids the proinflammatory necrotic death of a membrane-damaged cell.
authors.affiliation: Program in Cellular and Molecular Medicine, Children's Hospital and Immune Disease Institute, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Jerome
authors.initials: J
authors.lastname: Thiery
authors.forename: Dennis
authors.initials: D
authors.lastname: Keefe
authors.forename: Saviz
authors.initials: S
authors.lastname: Saffarian
authors.forename: Denis
authors.initials: D
authors.lastname: Martinvalet
authors.forename: Michael
authors.initials: M
authors.lastname: Walch
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Boucrot
authors.forename: Tomas
authors.initials: T
authors.lastname: Kirchhausen
authors.forename: Judy
authors.initials: J
authors.lastname: Lieberman
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D002462:Cell Membrane / Q000276:immunology* / Q000378:metabolism; D002966:Clathrin / Q000276:immunology* / Q000378:metabolism; D034281:Dynamins / Q000276:immunology* / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000276:immunology*; D011992:Endosomes / Q000276:immunology / Q000378:metabolism; D053804:Granzymes / Q000276:immunology* / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D054353:Perforin / Q000276:immunology* / Q000378:metabolism; D051381:Rats
chemical_list: D002966:Clathrin; D054353:Perforin; C509213:GZMB protein, human; D053804:Granzymes; C509215:Gzmb protein, rat; D034281:Dynamins