title: Functional involvement of cathepsin W in the cytotoxic activity of NK-92 cells.
abstract: Human cathepsin W (lymphopain) is a papain-like cysteine protease of unknown function that is specifically expressed in natural killer (NK) cells and to a lesser extent in cytotoxic T cells (CTL). In order to analyze the functional importance of cathepsin W for the cytotoxic process, we investigated NK-92 cells that have an NK cell-like phenotype and express cathepsin W. NK-92 cells possess strong cytotoxic activity against Jurkat and K562 cells. The cytotoxic activity of NK-92 cells against K562 was decreased in the presence of antisense phosphorothioate oligonucleotides against the cathepsin W-cDNA. Western blot analysis showed that the impaired cytotoxic activity of NK-92 cells was accompanied by reduced amounts of cathepsin W in the antisense-treated cells. In addition, co-cultivation experiments between NK-92 and K562 cells revealed a time-dependent decrease of cathepsin W by Western blot and immunofluorescence analysis during the cytotoxic attack, whereas CD56 expression of NK-92 cells was not affected. During cytotoxic attack, cathepsin W was neither targeted to K562 cells or other subcellular compartments, as shown by immunofluorescence analysis. The decrease of cathepsin W protein was associated with stable cathepsin W transcript levels. Control experiments using HT-29 cells, which are resistant against NK-92-mediated cytotoxicity, showed no change of cathepsin W expression, implying that the decrease of cathepsin W in the NK-92/K562 assay is linked to the cytotoxic process. Although the exact function of cathepsin W with respect to its enzymatic activity and its site of action still needs to be elucidated, our data demonstrate for the first time that cathepsin W is important for cellular cytotoxicity mediated by NK cells.
authors.affiliation: Department of Gastroenterology, Otto-von-Guericke University Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany. thomas.wex@medizin.uni-magdeburg.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Wex
authors.forename: Heike
authors.initials: H
authors.lastname: Wex
authors.forename: Roland
authors.initials: R
authors.lastname: Hartig
authors.forename: Skadi
authors.initials: S
authors.lastname: Wilhelmsen
authors.forename: Peter
authors.initials: P
authors.lastname: Malfertheiner
mesh_terms: D001483:Base Sequence; D056664:Cathepsin W; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000502:physiology*; D003602:Cytotoxicity, Immunologic; D015870:Gene Expression; D006801:Humans; D019169:Jurkat Cells; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000201:enzymology* / Q000276:immunology*; D008856:Microscopy, Fluorescence; D020319:Oligodeoxyribonucleotides, Antisense / Q000235:genetics / Q000494:pharmacology; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D020319:Oligodeoxyribonucleotides, Antisense; D012333:RNA, Messenger; D002403:Cathepsins; C534187:CTSW protein, human; D056664:Cathepsin W; D003546:Cysteine Endopeptidases