Lu Y, Morley P, Durkin J P
Cellular Neurobiology Group, Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario.
Cell Signal. 1999 Apr;11(4):275-85. doi: 10.1016/s0898-6568(98)00061-8.
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.
白细胞介素-2（IL-2）在免疫反应的产生和调节中起着至关重要的作用，包括T细胞存活的重要方面。IL-2介导的T细胞存活似乎依赖于一组膜相关蛋白激酶C（PKC）的激活，这种激活发生在没有可检测到的该酶从胞质溶胶向膜的转位的情况下。在本报告中，我们研究了细胞毒性T细胞系CTLL-2在IL-2刺激后负责这种PKC激活的机制。发现IL-2刺激后激活的酪氨酸激酶活性与细胞因子对PKC的激活无关。另一方面，一种百日咳毒素（PTX）敏感的G蛋白似乎确实与PKC激活偶联，因为PTX有效地阻断了IL-2刺激的PKC活性。IL-2刺激后二酰基甘油（DAG）增加，但肌醇1,3,5-三磷酸（IP3）和细胞内Ca2+没有增加，这表明DAG是通过磷脂酰胆碱-磷脂酶C（PC-PLC）或磷脂酰胆碱-磷脂酶D（PC-PLD）途径产生的。IL-2引起的DAG增加可能是激活膜驻留PKC所必需的，因为外源性应用的DAG在完整细胞和分离的膜中均刺激了这一PKC池。IL-2还增加了CTLL-2细胞中花生四烯酸（AA）的产生，可能是通过磷脂酶A2（PLA2），因为PLA2抑制剂油酰氧基乙基磷酸胆碱和AACOCF3（AACF）有效地阻断了IL-2刺激的PKC激活。外源性AA也增加了完整细胞和分离膜中的PKC活性，这表明IL-2受体刺激产生的AA可能与PKC激活有关。这些结果表明，IL-2对膜驻留PKC的激活涉及多种第二信使，包括G蛋白、DAG和AA。
