Platelet-derived-growth-factor stimulation of the p42/p44 mitogen-activated protein kinase pathway in airway smooth muscle: role of pertussis-toxinsensitive G-proteins, c-Src tyrosine kinases and phosphoinositide 3-kinase
Platelet-derived-growth-factor stimulation of the p42/p44 mitogen-activated protein kinase pathway in airway smooth muscle: role of pertussis-toxinsensitive G-proteins, c-Src tyrosine kinases and phosphoinositide 3-kinase
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DOI：
10.1042/0264-6021:3370171
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发表时间：
1999-01-15
影响因子：
4.1
通讯作者：
Pyne, NJ
中科院分区：
文献类型：
--
作者：
Conway, AM;Rakhit, S;Pyne, NJ
在培养的气道平滑肌（ASM）细胞中研究了血小板衍生生长因子受体（PDGFR）激活丝裂原激活蛋白激酶（p（42）/p（44）MAPK）途径的机制。我们发现百日咳毒素（PTX，用于灭活异源三聚体 G 蛋白 G(i)）诱导大约PDGF 使 c-Src 和 p42/p44 MAPK 的激活降低 40-50%。 c-Src 抑制剂 PPI 证实了 c-Src 的重要作用，它消除了 p42/p44 MAPK 激活（PPI 和 PTX 对 PDGFR 酪氨酸磷酸化没有影响）。此外，c-Src 和 p42/p44 MAPK 激活的 PTX 依赖性减少似乎是相关的。这些发现表明 GFR 可以利用 PTX 敏感的 G 蛋白 G(1) 来调节 c-Src 和随后的 p42/p44 MAPK( 激活)。磷酸肌醇 3-激酶 (PI3K) 已被其他人证明参与 p42/p44 MAPK 激活。实验证实了这一点，实验表明 PI3K 抑制剂（渥曼青和 LY294002) 减少 PDGF 对 p42/p44 MAPK 的激活。 PDGF 刺激细胞的 Grb-2 免疫沉淀物中 PI3K 活性增加，而用 PTX 预处理这些细胞则降低了 PI3K 活性。这些发现表明，G(i) 也可能促进 Grb-2-PI3K 复合物的形成，并且 Grb-2 可能是 PI3K 整合到复合物中的位点。 p42/p44 MAPK 级联。总之，我们的结果表明，G(i) 使 PDGFR 能够更有效地向 p42/p44 MAPK 发出信号，这似乎是通过调节 c-Src 和 Grb-2/PI3K（p42/p44 MAPK 级联中的中间体）来实现的。
The mechanism used by the platelet-derived growth factor receptor (PDGFR) to activate the mitogen-activated- protein kinase (p(42)/p(44) MAPK) pathway was investigated in cultured airway smooth muscle (ASM) cells. We have found that pertussis toxin (PTX, which was used to inactivate the heterotrimeric G-protein G(i)) induced an approx. 40-50 % decrease in the activation of c-Src and p42/p44 MAPK by PDGF. An essential role for c-Src was confirmed using the c-Src inhibitor, PPI, which abolished p42/p44 MAPK activation (PPI and PTX were without effect on PDGFR tyrosine phosphorylation). Furthermore, the PTX-dependent decrease in c-Src and p42/p44 MAPK activation appeared correlated. These findings suggest GFR can utilize the PTX-sensitive G-protein, G(1), to regulate c-Src and subsequent p42/p44 MAPK( activation. Phosphoinositide 3-kinase (PI3K) has been shown by others to be involved in p42/p44 MAPK activation. This is confirmed here by experiments which showed that PI3K inhibitors (wortmannin and LY294002) reduced the activation of p42/p44 MAPK by PDGF. PI3K activity was increased in Grb-2 immunoprecipitates from PDGF-stimulated cells and was decreased by pretreating these cells with PTX. These findings show that G(i) might also promote Grb-2-PI3K complex formation and that Grb-2 may be a site at which PI3K is integrated into the p42/p44 MAPK cascade. In conclusion, our results demonstrate that G(i) enables the PDGFR to signal more efficiently to p42/p44 MAPK, and this appears to be achieved through the regulation of c-Src and Grb-2/PI3K, which are intermediates in the p42/p44 MAPK cascade.