title: Molecular mechanism of the activation-induced cell death inhibition mediated by a p70 inhibitory killer cell Ig-like receptor in Jurkat T cells.
abstract: In this study we investigated the molecular mechanism of the activation-induced cell death (AICD) inhibition mediated by a p70 inhibitory killer cell Ig-like receptor (KIR3DL1, also called NKB1) in Jurkat T cells. Using stable Jurkat transfectants that express KIR or CD8-KIR fusion proteins we have shown for the first time that KIR inhibits, in a ligation-independent manner, the AICD induced by PHA, PMA/ionomycin, or anti-CD3 Ab. The AICD inhibition mediated by KIR appears to result from the blockade of Fas ligand induction upon activation of the Jurkat transfectants. Moreover, the membrane-proximal 20 aa of the KIR cytoplasmic tail were determined to play a crucial role in this process. Since the membrane-proximal portion of the KIR cytoplasmic tail contains a putative protein kinase C (PKC) substrate site, we investigated the molecular interaction between KIR and PKC. Immunoprecipitation analysis demonstrated that KIR constitutively bound both to PKCalpha, a conventional Ca(2+)-dependent PKC, and to PKCtheta, a novel Ca(2+)-independent PKC. Furthermore, an in vitro kinase assay revealed that PKC activation was blocked after PHA stimulation in Jurkat transfectants expressing KIR. These observations were supported by the finding that a recombinant KIR cytoplasmic tail also appeared to inhibit PKCalpha activation in vitro. Taken together these data strongly suggest that KIR inhibits the AICD of T cells by blocking Fas ligand induction upon stimulation, in a process that seems to be accomplished by PKC recruitment to the membrane-proximal PKC binding site and subsequent inhibition of PKC activation against the activating stimuli.
authors.affiliation: Department of Microbiology and Brain, Korea 21 Project of Medical Sciences, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Yong-Joon
authors.initials: YJ
authors.lastname: Chwae
authors.forename: Mi Jung
authors.initials: MJ
authors.lastname: Chang
authors.forename: Sang Myun
authors.initials: SM
authors.lastname: Park
authors.forename: Ho
authors.initials: H
authors.lastname: Yoon
authors.forename: Hyun-Joo
authors.initials: HJ
authors.lastname: Park
authors.forename: Se Jong
authors.initials: SJ
authors.lastname: Kim
authors.forename: Jongsun
authors.initials: J
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D003593:Cytoplasm / Q000737:chemistry / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D004075:Diglycerides / Q000494:pharmacology; D053222:Fas Ligand Protein; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D019169:Jurkat Cells; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism; D008024:Ligands; D008213:Lymphocyte Activation / Q000187:drug effects / Q000235:genetics; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D010718:Phosphatidylserines / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051571:Protein Kinase C-alpha; D000074121:Protein Kinase C-theta; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D054340:Receptors, KIR; D054341:Receptors, KIR3DL1; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D019014:fas Receptor / Q000378:metabolism
chemical_list: D004075:Diglycerides; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D007527:Isoenzymes; C515083:KIR3DL1 protein, human; D008024:Ligands; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D010718:Phosphatidylserines; D010835:Phytohemagglutinins; D011971:Receptors, Immunologic; D054340:Receptors, KIR; D054341:Receptors, KIR3DL1; D011994:Recombinant Proteins; D019014:fas Receptor; C098698:p70 natural killer cell receptor; D015759:Ionomycin; C496628:PRKCA protein, human; C076233:PRKCQ protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D000074121:Protein Kinase C-theta; D013755:Tetradecanoylphorbol Acetate