Molecular Mechanism of the Activation-Induced Cell Death Inhibition Mediated by a p70 Inhibitory Killer Cell Ig-Like Receptor in Jurkat T Cells

• DOI: 10.4049/jimmunol.169.7.3726
• Publication Date: 2014-04-21T23:18:01Z
• Authors: Yong-Joon Chwae; Mi Jung Chang; Sang Myun Park; Ho Yoon; Hyun-Joo Park; Se Jong Kim; Jongsun Kim
• Keywords: Diglycerides/pharmacology; Cytoplasm; Apoptosis; Ligands; Lymphocyte Activation; Jurkat Cells; Apoptosis/genetics; Receptors; Membrane Proteins/immunology; Killer Cells; Isoenzymes/metabolism; Recombinant Proteins/pharmacology; Lymphocyte Activation*/drug effects; Protein Kinase C; 0303 health sciences; Membrane Glycoproteins; Cytoplasm/immunology; Ionomycin; Isoenzymes/antagonists & inhibitors; Phytohemagglutinins/pharmacology; KIR; Isoenzymes; Killer Cells, Natural; Immunologic/biosynthesis; Cytoplasm/chemistry; Peptide Fragments/immunology; T-Lymphocytes/cytology; 570; Fas Ligand Protein; Protein Kinase C-alpha; Protein Kinase C/antagonists & inhibitors; Molecular Sequence Data; Membrane Glycoproteins/antagonists & inhibitors; Protein Kinase C/metabolism; Phosphatidylserines; Diglycerides; Apoptosis/immunology*; 03 medical and health sciences; T-Lymphocytes/drug effects; Cytoplasm/enzymology; KIR3DL1; Humans; Amino Acid Sequence; Membrane Proteins/genetics; Peptide Fragments/genetics; Phytohemagglutinins; Phosphatidylserines/pharmacology; Peptide Fragments/pharmacology; Membrane Proteins/pharmacology; Immunologic/genetics; Apoptosis/drug effects; Ionomycin/pharmacology; Membrane Proteins; Immunologic/physiology*; Cytoplasm/genetics; Natural/metabolism; Lymphocyte Activation*/genetics; Peptide Fragments; Natural/immunology; Protein Kinase C-theta; Membrane Glycoproteins/biosynthesis

AbstractIn 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 PKCα, a conventional Ca2+-dependent PKC, and to PKCθ, a novel Ca2+-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 PKCα 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.