title: Proteasome regulation of activation-induced T cell death.
abstract: Lactacystin, a microbial metabolite that inhibits protease activity only in the proteasome, was used to study the role of the proteasome in the activation-induced cell death (AICD) of T cells. Lactacystin induces DNA fragmentation and apoptosis in a T cell hybridoma (DO.11. 10) in a dose-dependent manner. Between 1 and 10 microM, the mildly cytotoxic lactacystin inhibited the AICD of DO.11.10 cells cultured in anti-CD3-coated wells. Degradation of IkappaBbeta and the translocation of the NF-kappaB (p50/RelA) into the nucleus, which occurred at 1.5 hr after anti-CD3 activation, were inhibited by lactacystin. Lactacystin did not inhibit the expression of nuclear transcription factor Oct-1. The activation-induced expression of the immediate-early gene, Nur77, and the T cell death genes, CD95 (Fas) and CD95 ligand (FasL), were inhibited. Functional expression of FasL cytotoxicity and the increase of cell surface Fas were also inhibited. Lactacystin must be added within 2 hr of activation to efficiently block AICD. In addition, lactacystin failed to inhibit the killing of DO.11.10 by FasL-expressing allo-specific cytotoxic effector cells. These observations strongly suggest a direct link between the proteasome-dependent degradation of IkappaBbeta and the AICD that occurs through activation of the FasL gene and up-regulation of the Fas gene.
authors.affiliation: Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: H
authors.initials: H
authors.lastname: Cui
authors.forename: K
authors.initials: K
authors.lastname: Matsui
authors.forename: S
authors.initials: S
authors.lastname: Omura
authors.forename: S L
authors.initials: SL
authors.lastname: Schauer
authors.forename: R A
authors.initials: RA
authors.lastname: Matulka
authors.forename: G E
authors.initials: GE
authors.lastname: Sonenshein
authors.forename: S T
authors.initials: ST
authors.lastname: Ju
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D003546:Cysteine Endopeptidases / Q000276:immunology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053222:Fas Ligand Protein; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000276:immunology; D051379:Mice; D009097:Multienzyme Complexes / Q000276:immunology*; D046988:Proteasome Endopeptidase Complex; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology
chemical_list: D015853:Cysteine Proteinase Inhibitors; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D009097:Multienzyme Complexes; C067713:lactacystin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D000111:Acetylcysteine