Protein kinase ctheta cooperates with calcineurin to induce Fas ligand expression during activation-induced T cell death.
Activation-induced cell death is mediated by the TCR-induced expression of the Fas ligand (FasL) on the surface of T cells, followed by binding to its receptor Fas. FasL expression is induced by stimulating T cells with a combination of phorbol ester and Ca2+ ionophore, implicating a role for protein kinase C (PKC) in this process. However, the precise mechanisms that regulate FasL expression, including the contribution of distinct T cell-expressed PKC isoforms, are poorly understood. Herein, we report that PKCtheta, a Ca2+-independent PKC isoform that we have previously isolated as a PKC enzyme selectively expressed in T cells, plays an important role in these processes. A constitutively active PKCtheta mutant preferentially induced FasL expression and activated the corresponding gene promoter; conversely, a dominant-negative PKCtheta mutant blocked FasL expression induced by anti-CD3 or PMA plus ionomycin stimulation. Furthermore, PKCtheta synergized with calcineurin to provide a potent stimulus for FasL promoter activation. Full activation of the promoter required its binding sites for the transcription factors NF-AT, AP-1, and NF-kappaB. The biological significance of these findings is implicated by the finding that rottlerin, a selective PKCtheta inhibitor, blocked FasL induction by anti-CD3 or PMA plus ionomycin stimulation and, consequently, protected human Jurkat T cells and the mouse T cell hybridoma A1.1 from activation-induced cell death.
Villalba
M
M
Divisions ofCell Biology and Cellular Immunolgy, La Jolla Institute for Allergy and Immunology, San Diego, CA 92121, USA.
Kasibhatla
S
S
Genestier
L
L
Mahboubi
A
A
Green
D R
DR
Altman
A
A
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001578:Benzopyrans / Q000494:pharmacology; D001665:Binding Sites; D019703:Calcineurin / Q000378:metabolism*; D002227:Carbazoles / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004347:Drug Interactions; D053222:Fas Ligand Protein; D005786:Gene Expression Regulation; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019169:Jurkat Cells; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D051379:Mice; D009154:Mutation; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000074121:Protein Kinase C-theta; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D000098:Acetophenones; D001578:Benzopyrans; D002227:Carbazoles; D004268:DNA-Binding Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D007211:Indoles; D007527:Isoenzymes; D008562:Membrane Glycoproteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; C081021:Go 6976; D015759:Ionomycin; C085746:rottlerin; C076233:PRKCQ protein, human; C489593:Prkcq protein, mouse; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta; D019703:Calcineurin; D013755:Tetradecanoylphorbol Acetate