Interaction between protein kinase C-dependent and G protein-dependent pathways in the regulation of natural killer cell granule exocytosis.
Interaction between protein kinase C-dependent and G protein-dependent pathways in the regulation of natural killer cell granule exocytosis.
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DOI：
10.1016/s0021-9258(18)35930-1
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发表时间：
1992-11
期刊：
影响因子：
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通讯作者：
A. Ting;R. A. Schoon;R. Abraham;P. Leibson
中科院分区：
文献类型：
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作者：
A. Ting;R. A. Schoon;R. Abraham;P. Leibson
自然杀伤 (NK) 细胞与易感肿瘤细胞或抗体包被靶标的结合会导致 NK 细胞中磷脂酶 C (PLC) 的快速激活。 PLC 激活产生肌醇-1,4,5-三磷酸和 sn-1,2-二酰基甘油作为第二信使，进而分别增加细胞内游离钙浓度 ([Ca2+]i) 和蛋白激酶 C (PKC) 活性。这些近端信号引发一系列尚未定义的生化事件，最终导致预先形成的细胞毒性颗粒的胞吐作用。为了研究颗粒胞吐作用中涉及的信号转导途径，我们利用链球菌溶血素-O-通透的人 NK 细胞作为我们的实验模型。我们的初步研究表明，PKC（使用佛波酯，PMA）或G蛋白依赖性途径（使用鸟苷-5'-O-（3-硫代三磷酸）（GTPγS））的单独激活以时间、浓度和Ca（2+）依赖性方式刺激颗粒胞吐作用。 PMA 刺激的胞吐作用被星形孢菌素或 PKC 假底物拮抗肽抑制，但不受 GDP 影响。相比之下，GTP γ S 刺激的胞吐作用被 GDP 有效抑制，但不能被星形孢菌素或 PKC 假底物拮抗剂抑制。这些观察结果表明 NK 细胞胞吐作用可以通过至少两个独立的途径来刺激；一个涉及 PKC，另一个涉及 G 蛋白。然而，PMA 和 GTP gamma S 的共刺激可协同增强胞吐作用，这表明尽管这两种胞吐途径在生化上不同，但两种途径之间的串扰可能会有效影响胞吐过程。这些结果定义了 NK 细胞颗粒胞吐过程中 PKC 和 G 蛋白依赖性途径的调节作用。
The binding of natural killer (NK) cells to either susceptible tumor cells or antibody-coated targets results in rapid activation of phospholipase C (PLC) in NK cells. PLC activation generates inositol-1,4,5-trisphosphate and sn-1,2-diacylglycerol as second messengers, which, in turn, increase intracellular free calcium concentrations ([Ca2+]i) and protein kinase C (PKC) activity, respectively. These proximal signals initiate a cascade of as yet undefined biochemical events, leading eventually to the exocytosis of preformed cytotoxic granules. To investigate the signal transduction pathways involved in granule exocytosis, we utilized streptolysin-O-permeabilized human NK cells as our experimental model. Our initial studies indicated that the separate activation of either PKC (using the phorbol ester, PMA) or G protein-dependent pathways (using guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S)) stimulated granule exocytosis in a time-, concentration-, and Ca(2+)-dependent manner. PMA-stimulated exocytosis was inhibited by staurosporine or a PKC pseudosubstrate antagonist peptide, but was not affected by GDP. In contrast, GTP gamma S-stimulated exocytosis was effectively inhibited by GDP, but not by staurosporine or the PKC pseudosubstrate antagonist. These observations suggest that NK cell exocytosis can be stimulated by at least two separate pathways; one involving PKC and the other involving a G protein. However, co-stimulation with PMA and GTP gamma S synergistically enhanced exocytosis, suggesting that even though the two exocytotic pathways were biochemically distinct, cross-talk between the two pathways may potently influence the exocytotic process. These results define a regulatory role for PKC- and G protein-dependent pathways during granule exocytosis from NK cells.