title: Sensitization of stefin B-deficient thymocytes towards staurosporin-induced apoptosis is independent of cysteine cathepsins.
abstract: Stefin B (cystatin B) is an inhibitor of lysosomal cysteine cathepsins and does not inhibit cathepsin D, E (aspartic) or cathepsin G (serine) proteinases. In this study, we have investigated apoptosis triggered by camptothecin, staurosporin (STS), and anti-CD95 monoclonal antibody in the thymocytes from the stefin B-deficient mice and wild-type mice. We have observed increased sensibility to STS-induced apoptosis in the thymocytes of stefin B-deficient mice. Pretreatment of cells with pan-caspase inhibitor z-Val-Ala-Asp(OMe)-fluoromethylketone completely inhibited phosphatidylserine externalization and caspase activation, while treatment with inhibitor of calpains- and papain-like cathepsins (2S,3S)-trans-epoxysuccinyl-leucylamido-3-methyl-butane ethyl ester did not prevent caspase activation nor phosphatidylserine exposure. We conclude that sensitization to apoptosis induced by STS in thymocytes of stefin B-deficient and wild-type mice is not dependent on cathepsin inhibition by stefin B.
authors.affiliation: Department of Biochemistry and Molecular Biology, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia. natasa.kopitar@ijs.si
authors.forename: Natasa
authors.initials: N
authors.lastname: Kopitar-Jerala
authors.forename: Ana
authors.initials: A
authors.lastname: Schweiger
authors.forename: Richard M
authors.initials: RM
authors.lastname: Myers
authors.forename: Vito
authors.initials: V
authors.lastname: Turk
authors.forename: Boris
authors.initials: B
authors.lastname: Turk
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002478:Cells, Cultured; D055313:Cystatin B; D015891:Cystatins / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D051379:Mice; D008807:Mice, Inbred BALB C; D019311:Staurosporine / Q000494:pharmacology*; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; C524992:Cstb protein, mouse; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D055313:Cystatin B; D002403:Cathepsins; D019311:Staurosporine