Initial signaling of the fibronectin receptor (α5β1 integrin) in hepatic stellate cells is independent of tyrosine phosphorylation
Initial signaling of the fibronectin receptor (α5β1 integrin) in hepatic stellate cells is independent of tyrosine phosphorylation
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DOI：
10.1016/s0168-8278(03)00161-2
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发表时间：
2003-07-01
影响因子：
25.7
通讯作者：
Luxon, BA
中科院分区：
文献类型：
--
作者：
Milliano, MT;Luxon, BA
背景/目的：肝星状细胞（HSC）的激活在肝纤维化中发挥着不可或缺的作用。 HSC 激活会增加纤连蛋白 (α(5)β(1)) 受体的表达，并且 α(5)β(1) 与细胞外基质之间的相互作用会增加胶原蛋白的合成。目前尚不清楚 α(5)β(1) 受体的信号传导如何引发这些变化。我们的目的是确定激活的HSC中α(5)β(1)刺激后的信号级联反应。方法：从雄性Sprague-Dawley大鼠中分离HSC。将活化的 HSC 暴露于涂有纤连蛋白（α(5)β(1) 配体）或 D-聚赖氨酸（惰性对照）的珠子。 HSC 用针对信号分子类别的 FTC 标记抗体进行染色。使用金雀异黄素或除草霉素 A 阻断酪氨酸磷酸化。测定具有局部免疫染色（表明信号蛋白积累）的珠子分数。结果：大多数细胞骨架蛋白、Src 底物、Src 激酶以及 ERK 和 JNK 信号分子家族成员需要肌动蛋白细胞骨架组织和酪氨酸激酶介导的磷酸化才能积累。几种蛋白质（例如张力蛋白、FAK）在没有酪氨酸磷酸化的情况下积累。结论：α(5)β(1) 整联蛋白-配体相互作用诱导细胞骨架分子的积累，激活多种激酶途径。 α(5)β(1) 的初始整合素信号传导与细胞骨架蛋白相关，并且独立于酪氨酸磷酸化。我们认为可能存在细胞骨架的变化，从而减少 HSC 的激活。 (C) 2003 年欧洲肝脏研究协会。由 Elsevier Science B.V. 出版。保留所有权利。
Background/Aims: Activation of hepatic stellate cells (HSC) plays an integral role in hepatic fibrosis. HSC activation increases fibronectin (alpha(5)beta(1)) receptor expression and interactions between alpha(5)beta(1) and the extracellular matrix increase collagen synthesis. It is unclear how signaling by the alpha(5)beta(1) receptor initiates these changes. We aimed to determine the signaling cascade after alpha(5)beta(1) stimulation in activated HSC.Methods: HSC were isolated from male Sprague-Dawley rats. Activated HSC were exposed to beads coated With fibronectin (ligand for alpha(5)beta(1)) or D-polylysine (inert control). HSC were stained with FTC-labeled antibodies against classes of signaling molecules. Tyrosine phosphorylation was blocked using genistein or herbimycin A. The fraction of beads with localized immunostaining (indicating accumulation of signaling protein) was determined.Results: The majority of cytoskeletal proteins, Src substrates, Src kinases and members of the ERK and JNK signaling molecule families require actin cytoskeletal organization and tyrosine-kinase-mediated phosphorylation to accumulate. Several proteins (e.g. tensin, FAK) accumulated in the absence of tyrosine phosphorylation.Conclusions: The alpha(5)beta(1) integrin-ligand interaction induces accumulation of cytoskeletal molecules, activating multiple kinase pathways. Initial integrin signaling by alpha(5)beta(1) are associated with cytoskeletal proteins and are independent of tyrosine phosphorylation. We suggest that there may be cytoskeletal changes that may be targeted to diminish HSC activation. (C) 2003 European Association for the Study of the Liver. Published by Elsevier Science B.V. All rights reserved.