P2-purinoceptor regulation of surfactant phosphatidylcholine secretion. Relative roles of calcium and protein kinase C.
P2-purinoceptor regulation of surfactant phosphatidylcholine secretion. Relative roles of calcium and protein kinase C.
复制标题
P2-嘌呤受体调节表面活性剂磷脂酰胆碱分泌。
DOI：
10.1042/bj2660407
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Singleton,FM
中科院分区：
文献类型：
--
作者：
Rice,WR;Dorn,CC;Singleton,FM
Ca2+ 和蛋白激酶 C 均被提议作为 II 型肺泡细胞随后分泌磷脂酰胆碱的细胞内信号。我们通过利用外源 ATP 和佛波酯 TPA（12-O-十四烷酰佛波醇 13-乙酸酯）作为促分泌剂，以及 MAPTAM 螯合细胞内 Ca2+ 和鞘氨醇来抑制内源性蛋白激酶 C，确定了 Ca2+ 和蛋白激酶 C 在调节表面活性剂磷脂酰胆碱分泌中的相对作用。将 II 型细胞暴露于 P2-嘌呤受体激动剂， ATP 导致分离的 II 型肺泡细胞的表面活性剂磷脂酰胆碱分泌呈剂量依赖性增加，EC50（产生最大反应的 50% 浓度）为 2 µM。向 II 型细胞施用外源 ATP 还会导致三磷酸肌醇产量、Ca2+ 动员和 [3H]佛波醇 12,13-二丁酸 ([3H]PDBu) 结合呈剂量依赖性增加，作为蛋白激酶 C 易位的量度。每种情况下的 EC50 均为 1-5 microM，表明这些事件与表面活性剂磷脂酰胆碱分泌有关。用不可水解的 GTP 类似物 (GTP[S]) 负载 II 型细胞可抑制 ATP 诱导的 Ca2+ 动员，支持 II 型细胞 P2 嘌呤受体通过 GTP 结合蛋白与磷脂酶 C 偶联的假设。 ATP 诱导的胞质 Ca2+ 升高也被 MAPTAM（一种可渗透细胞的 EGTA 类似物）抑制 90%，但 MAPTAM 对 ATP 诱导的表面活性剂磷脂酰胆碱分泌没有影响。鞘氨醇抑制 ATP 和 TPA 诱导的表面活性剂磷脂酰胆碱分泌以及 [3H]PDBu 结合，具有相似的 IC50（浓度产生最大抑制的 50%）（10 µM）。鞘氨醇不影响特布他林诱导的表面活性剂磷脂酰胆碱分泌，对外源ATP诱导的Ca2+动员没有显着影响。这些结果与蛋白激酶 C 在调节 P2-嘌呤受体诱导的表面活性剂磷脂酰胆碱分泌中的显着作用一致，并表明 Ca2+ 动员不是 ATP 诱导的表面活性剂磷脂酰胆碱分泌的必要步骤。
Ca2+ and protein kinase C have both been proposed as intracellular signals for subsequent phosphatidylcholine secretion by alveolar Type II cells. We have determined the relative roles of Ca2+ and protein kinase C in regulating surfactant phosphatidylcholine secretion by utilizing exogenous ATP and the phorbol ester TPA (12-O-tetradecanoylphorbol 13-acetate) as secretagogues, along with MAPTAM to chelate intracellular Ca2+ and sphingosine to inhibit endogenous protein kinase C. Exposure of Type II cells to the P2-purinoceptor agonist, ATP, results in a dose-dependent increase in surfactant phosphatidylcholine secretion from isolated alveolar Type II cells with an EC50 (concn. producing 50% of maximal response) of 2 microM. Administration of exogenous ATP to Type II cells also results in a dose-dependent increase in inositol trisphosphate production, Ca2+ mobilization and [3H]phorbol 12,13-dibutyrate ([3H]PDBu) binding as a measure of protein kinase C translocation. The EC50 in each case is 1-5 microM, indicating association of these events with surfactant phosphatidylcholine secretion. Loading Type II cells with non-hydrolysable GTP analogue (GTP[S]) inhibited ATP-induced Ca2+ mobilization, supporting the hypothesis that Type II cell P2-purinoceptors are coupled to phospholipase C via a GTP-binding protein. The ATP-induced elevation of cytosolic Ca2+ was also inhibited by MAPTAM (a cell-permeant EGTA analogue) by 90%, but MAPTAM was without effect on surfactant phosphatidylcholine secretion induced by ATP. Sphingosine inhibited both ATP- and TPA-induced surfactant phosphatidylcholine secretion as well as [3H]PDBu binding with a similar IC50 (concn. producing 50% of maximal inhibition) (10 microM). Sphingosine did not affect surfactant phosphatidylcholine secretion induced by terbutaline and did not have a significant effect on Ca2+ mobilization induced by exogenous ATP. These results are consistent with a prominent role for protein kinase C in regulation of P2-purinoceptor-induced surfactant phosphatidylcholine secretion, and indicate that Ca2+ mobilization is not a necessary step for ATP-induced surfactant phosphatidylcholine secretion.