Extracellular signal regulated kinases are key mediators of mitogenic signals in rat pancreatic stellate cells
Extracellular signal regulated kinases are key mediators of mitogenic signals in rat pancreatic stellate cells
复制标题
DOI：
10.1136/gut.51.4.579
复制
发表时间：
2002-10-01
期刊：
影响因子：
24.5
通讯作者：
Liebe, S
中科院分区：
文献类型：
--
作者：
Jaster, R;Sparmann, G;Liebe, S
背景：胰腺星状细胞 (PSC) 与胰腺纤维化有关，因为它们响应细胞因子等促纤维化介质的激活而合成数量增加的细胞外基质蛋白。目的：本研究的目的是分析参与 PSC 激活的细胞因子受体刺激的信号通路。使用 PSC 的大鼠培养模型，我们还测试了血小板衍生生长因子 (PDGF) 拮抗剂曲匹地尔和细胞外信号调节激酶 (ERK) 激活的特异性抑制剂 PD98059 抑制 PSC 生长的潜力。方法：用 PDGF 刺激培养的 PSC，并通过以下方法分析响应有丝分裂原而激活的信号转导途径： 免疫印迹、激酶测定和电泳迁移率变动测定。此外，对完成转分化为表达α-平滑肌肌动蛋白的肌成纤维细胞之前和之后PSC中激活的信号级联进行了比较。通过增殖测定分析 PDGF、曲匹地尔和 PD98059 的生物学效应，并将其与这些物质的分子效应相关联。结果：PDGF 诱导 Raf-1、ERK 1 和 2 以及 AP-1 蛋白的快速激活。转化生长因子β激活的转录因子Smad2被发现在不同转分化级别的PSC中被组成型磷酸化。此外，结果表明 ERK 活性与 PSC 激活诱导之间存在相关性。 Trapidil 有效抑制 PDGF 诱导的 ERK 激活，以及与 PD98059 一样的 PSC 增殖。结论：我们的数据表明，ERK 在调节 PSC 生长中发挥关键作用，并且抑制 ERK 信号通路可能成为防止这些细胞激活的策略。
Background: Pancreatic stellate cells (PSCs) have been implicated in pancreatic fibrosis as they synthesise increased amounts of extracellular matrix proteins in response to activation by profibrogenic mediators such as cytokines.Aims: The purpose of this study was to analyse cytokine receptor stimulated signalling pathways involved in PSC activation. Using a rat culture model of PSCs, we have also tested the potential of the platelet derived growth factor (PDGF) antagonist trapidil and PD98059, a specific inhibitor of extracellular signal regulated kinase (ERK) activation, to suppress PSC growth.Methods: Cultured PSCs were stimulated with PDGF, and the signal transduction pathways activated in response to the mitogen were analysed by immunoblotting, kinase assays, and electrophoretic mobility shift assays. Furthermore, comparison of signalling cascades activated in PSCs before and after completing transdifferentiation to alpha-smooth muscle actin expressing myofibroblasts was performed. Biological effects of PDGF, trapidil, and PD98059 were analysed by proliferation assays and correlated with molecular effects of the substances.Results: PDGF induced rapid activation of Raf-1, ERKs 1 and 2, as well as AP-1 proteins. The transforming growth factor beta activated transcription factor Smad2 was found to be constitutively phosphorylated in PSCs of different transdifferentiation grades. Furthermore, the results indicate a correlation between ERK activities and induction of PSC activation. Trapidil efficiently inhibited both PDGF induced ERK activation and, in common with PD98059, PSC proliferation.Conclusions: Our data suggest that ERKs play a key role in the regulation of PSC growth and that inhibition of the ERK signalling pathway may become a strategy to prevent activation of these cells.