title: Immunocytochemical localization of multicatalytic protease complex (proteasome) during generation of murine IL-2-activated natural killer (A-NK) cells.
abstract: Murine IL-2-activated, adherent natural killer (A-NK) cells produce proteolytic activities (including a chymase and a tryptase) which appear to be components of the proteasome/multicatalytic proteinase complex and appear to represent the mouse homologues of the rat A-NK cell A-NKP 2 and A-NKP 1 protease components. The chymase is readily inhibited by Z-Gly-Gly-Phe chloromethylketone (Z-GGF) and to a lesser extent by N-tosyl-L-phenylalanyl-chloromethylketone (TPCK). In addition, this activity is inhibited by 3,4-dichloroisocoumarin (DCI), a suicide inhibitor for both chymotryptic and tryptic proteolytic enzymes. Protease inhibitors reduced A-NK cell-mediated cytotoxicity against P815 target cells, most prominently with inhibitors of chymotryptic and tryptic enzymes, including TPCK, DCI and Z-GGF. A polyclonal rabbit antibody raised against rat liver proteasome immunofluorescently labeled the cytoplasm of 4-day-cultured murine A-NK cells, multiple granules in 5 to 6-day cultures and large intracytoplasmic pools in cells cultured longer. Ultrastructurally this shift in labeling over time corresponded to an immunogold redistribution to non-membrane delineated mucoid masses. A minor nuclear labeling was noted at all time points, whereas the cisternae of the endoplasmic reticulum or Golgi region were negative. It is concluded that murine A-NK cells synthesize and accumulate proteasome in large intracytoplasmic pools, non-delineated by membranes which can occupy up to 80% of the A-NK cellular volume. The potential function of the proteasome produced by A-NK cells including cell-mediated cytotoxicity against tumor target cells remains to be elucidated.
authors.affiliation: Department of Anatomy and Cell Biology, University of Göteborg, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Nannmark
authors.forename: R P
authors.initials: RP
authors.lastname: Kitson
authors.forename: B R
authors.initials: BR
authors.lastname: Johansson
authors.forename: A J
authors.initials: AJ
authors.lastname: Rivett
authors.forename: R H
authors.initials: RH
authors.lastname: Goldfarb
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000032:analysis*; D003593:Cytoplasm / Q000201:enzymology / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000201:enzymology / Q000648:ultrastructure; D003602:Cytotoxicity, Immunologic; D007150:Immunohistochemistry; D007376:Interleukin-2 / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000201:enzymology* / Q000276:immunology / Q000648:ultrastructure; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D009097:Multienzyme Complexes / Q000032:analysis*; D015388:Organelles / Q000201:enzymology; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex
chemical_list: D007376:Interleukin-2; D009097:Multienzyme Complexes; D011480:Protease Inhibitors; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex