Signalling events mediating the activation of protein kinase C by interleukin-2 in cytotoxic T cells.
Interleukin-2 (IL-2) plays a vital role in the generation and regulation of the immune response, including important aspects of T cell survival. IL-2-mediated survival of T cells appears to be dependent on the activation of a pool of membrane-associated protein kinase C (PKC) that occurs in the absence of detectable translocation of the enzyme from the cytosol to membranes. In this report we investigate the mechanism(s) responsible for this PKC activation after IL-2 stimulation in the cytotoxic T cell line, CTLL-2. Tyrosine kinase activity, activated after IL-2 stimulation, was found not to be linked to the activation of PKC by the cytokine. On the other hand, a pertussis toxin (PTX)-sensitive G protein did appear coupled to PKC activation since PTX effectively blocked IL-2 stimulated PKC activity. Diacylglycerols (DAG), but not inositol 1,3,5-triphosphate (IP3) and intracellular Ca2+, increased after IL-2 stimulation suggesting that DAGs were generated via the phosphatidylcholine-phospholipase C (PC-PLC) or phosphatidylcholine-phospholipase D (PC-PLD) pathways. The increase in DAG by IL-2 was probably necessary for activation of membrane-resident PKC since exogenously applied DAG stimulated this PKC pool in both intact cells and in isolated membranes. IL-2 also increased arachidonic acid (AA) production in CTLL-2 cells, probably via phospholipase A2 (PLA2) since the PLA2 inhibitors oleoyloxyethyl phosphocholine and AACOCF3 (AACF) effectively blocked IL-2 stimulated PKC activation. Exogenous AA also increased PKC activity in intact cells and isolated membranes, suggesting that AA produced by IL-2 receptor stimulation was probably linked to PKC activation. These results suggest that the activation of membrane-resident PKC by IL-2 involves multiple second messengers, including G proteins, DAG and AA.
Lu
Y
Y
Cellular Neurobiology Group, Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario.
Morley
P
P
Durkin
J P
JP
D016718:Arachidonic Acid / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D004075:Diglycerides / Q000096:biosynthesis; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism* / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D004075:Diglycerides; D007376:Interleukin-2; D016718:Arachidonic Acid; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D019204:GTP-Binding Proteins