20.500.12556/RUL-128778 Exocytosis of large-diameter lysosomes mediates interferon γ-induced relocation of MHC class II molecules toward the surface of astrocytes Astrocytes are the key homeostatic cells in the central nervous system; initiation of reactive astrogliosis contributes to neuroinflammation. Pro-inflammatory cytokine interferon γ (IFNγ) induces the expression of the major histocompatibility complex class II (MHCII) molecules, involved in antigen presentation in reactive astrocytes. The pathway for MHCII delivery to the astrocyte plasma membrane, where MHCII present antigens, is unknown. Rat astrocytes in culture and in organotypic slices were exposed to IFNγ to induce reactive astrogliosis. Astrocytes were probed with optophysiologic tools to investigate subcellular localization of immunolabeled MHCII, and with electrophysiology to characterize interactions of single vesicles with the plasmalemma. In culture and in organotypic slices, IFNγ augmented the astrocytic expression of MHCII, which prominently co-localized with lysosomal marker LAMP1-EGFP, modestly co-localized with Rab7, and did not co-localize with endosomal markers Rab4A, EEA1, and TPC1. MHCII lysosomal localization was corroborated by treatment with the lysosomolytic agent glycyl-L-phenylalanine-β-naphthylamide, which reduced the number of MHCII-positive vesicles. The surface presence of MHCII was revealed by immunolabeling of live non-permeabilized cells. In IFNγ-treated astrocytes, an increased fraction of large-diameter exocytotic vesicles (lysosome-like vesicles) with prolonged fusion pore dwell time and larger pore conductance was recorded, whereas the rate of endocytosis was decreased. Stimulation with ATP, which triggers cytosolic calcium signaling, increased the frequency of exocytotic events, whereas the frequency of full endocytosis was further reduced. In IFNγ-treated astrocytes, MHCII-linked antigen surface presentation is mediated by increased lysosomal exocytosis, whereas surface retention of antigens is prolonged by concomitant inhibition of endocytosis. astroglia inflammatory cytokines fusion pore adaptive immunity patch clamp lysosomes astroglia vnetni citokini fuzijske pore adaptivna imunost obliž lizosomi true false true Angleški jezik Slovenski jezik Članek v reviji 2021-07-28 15:11:55 2021-07-28 15:11:59 2022-09-07 04:17:08 0000-00-00 00:00:00 2020 0 0 Str. 3245-3264 iss. 16 Vol. 77 Aug. 2020 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 616-092 1420-682X 10.1007/s00018-019-03350-8 34551513 RAZ_Bozic_Mico_2020.pdf RAZ_Bozic_Mico_2020.pdf 1 70A3911DA2F86DD9148860B535EE6E00 5524407d4cf61ccb06ae0e767e4de89f62e19dba26581c5691ebff97190cf8ad 398554b7-efa5-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=145652 https://rd.springer.com/article/10.1007%2Fs00018-019-03350-8 0 56b83402-efa5-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=145653 Medicinska fakulteta 0 0 0