title: Endocytosis of Cytotoxic Granules Is Essential for Multiple Killing of Target Cells by T Lymphocytes.
abstract: CTLs are serial killers that kill multiple target cells via exocytosis of cytotoxic granules (CGs). CG exocytosis is tightly regulated and has been investigated in great detail; however, whether CG proteins are endocytosed following exocytosis and contribute to serial killing remains unknown. By using primary CTLs derived from a knock-in mouse of the CG membrane protein Synaptobrevin2, we show that CGs are endocytosed in a clathrin- and dynamin-dependent manner. Following acidification, endocytosed CGs are recycled through early and late, but not recycling endosomes. CGs are refilled with granzyme B at the late endosome stage and polarize to subsequent synapses formed between the CTL and new target cells. Importantly, inhibiting CG endocytosis in CTLs results in a significant reduction of their cytotoxic activity. Thus, our data demonstrate that continuous endocytosis of CG membrane proteins is a prerequisite for efficient serial killing of CTLs and identify key events in this process.
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, 66421 Homburg/Saar, Germany; and.
authors.forename: Hsin-Fang
authors.initials: HF
authors.lastname: Chang
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, 66421 Homburg/Saar, Germany; and.
authors.forename: Hawraa
authors.initials: H
authors.lastname: Bzeih
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, 66421 Homburg/Saar, Germany; and.
authors.forename: Claudia
authors.initials: C
authors.lastname: Schirra
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, 66421 Homburg/Saar, Germany; and.
authors.forename: Praneeth
authors.initials: P
authors.lastname: Chitirala
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, 66421 Homburg/Saar, Germany; and.
authors.forename: Mahantappa
authors.identifier: 0000-0002-0271-1696
authors.initials: M
authors.lastname: Halimani
authors.affiliation: Department of Physiology, University of Alberta, Edmonton T6G 2H7, Alberta, Canada.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Cordat
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, 66421 Homburg/Saar, Germany; and.
authors.forename: Elmar
authors.identifier: 0000-0003-0891-2373
authors.initials: E
authors.lastname: Krause
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, 66421 Homburg/Saar, Germany; and jrettig@uks.eu Varsha.Pattu@uks.eu.
authors.forename: Jens
authors.identifier: 0000-0001-6160-3954
authors.initials: J
authors.lastname: Rettig
authors.affiliation: Center for Integrative Physiology and Molecular Medicine, Saarland University, 66421 Homburg/Saar, Germany; and jrettig@uks.eu Varsha.Pattu@uks.eu.
authors.forename: Varsha
authors.initials: V
authors.lastname: Pattu
mesh_terms: D000818:Animals; D002966:Clathrin / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000276:immunology* / Q000502:physiology; D034281:Dynamins / Q000276:immunology / Q000378:metabolism; D004705:Endocytosis; D011992:Endosomes / Q000276:immunology / Q000378:metabolism; D005089:Exocytosis; D053804:Granzymes / Q000378:metabolism; D054992:Immunological Synapses; D051379:Mice; D050683:R-SNARE Proteins / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D002966:Clathrin; D050683:R-SNARE Proteins; D053804:Granzymes; D034281:Dynamins