Rac1 pathway mediates stretch response in pulmonary alveolar epithelial cells
Rac1 pathway mediates stretch response in pulmonary alveolar epithelial cells
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DOI：
10.1152/ajplung.00298.2012
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发表时间：
2013-07-01
影响因子：
4.9
通讯作者：
Margulies, Susan S.
中科院分区：
文献类型：
--
作者：
DiPaolo, Brian C.;Davidovich, Nurit;Margulies, Susan S.
肺泡上皮细胞（AEC）通过固定在肌动蛋白细胞骨架上的垫圈状细胞间紧密连接（TJ）维持肺血气屏障的完整性。我们以前已经表明，AEC单层拉伸周期和等双轴经历快速的幅度和频率依赖性肌动蛋白细胞骨架重塑，形成连接周围的肌动蛋白环（PJARs）。在这项工作中，我们发现，即使是10分钟的拉伸诱导Akt和LIM激酶（LIMK）的磷酸化增加，并减少cofilin磷酸化，这表明Rac 1/Akt途径参与这些拉伸介导的变化。我们证实，Rac 1抑制剂渥曼青霉素或EHT-1864减少拉伸刺激的Akt和LIMK磷酸化，Rac 1激动剂PIP 3或PDGF增加未拉伸细胞中这些蛋白的磷酸化。我们还证实，Rac 1通路抑制在拉伸调制的牵张诱导的变化occludin含量和单层渗透性，肌动蛋白重塑和PSTs的形成，和细胞死亡。作为进一步的验证，Rac GTP酶激活蛋白β（2）-嵌合体的过表达也在拉伸的单层中保留了单层屏障特性。总之，我们的数据表明，Rac 1的组成活性，这是必要的拉伸诱导激活的Rac 1下游蛋白质，介导拉伸诱导的渗透性和PdR形成的增加。
Alveolar epithelial cells (AECs) maintain the pulmonary blood-gas barrier integrity with gasketlike intercellular tight junctions (TJ) that are anchored internally to the actin cytoskeleton. We have previously shown that AEC monolayers stretched cyclically and equibiaxially undergo rapid magnitude- and frequency-dependent actin cytoskeletal remodeling to form perijunctional actin rings (PJARs). In this work, we show that even 10 min of stretch induced increases in the phosphorylation of Akt and LIM kinase (LIMK) and decreases in cofilin phosphorylation, suggesting that the Rac1/Akt pathway is involved in these stretch-mediated changes. We confirmed that Rac1 inhibitors wortmannin or EHT-1864 decrease stretch-stimulated Akt and LIMK phosphorylation and that Rac1 agonists PIP3 or PDGF increase phosphorylation of these proteins in unstretched cells. We also confirmed that Rac1 pathway inhibition during stretch modulated stretch-induced changes in occludin content and monolayer permeability, actin remodeling and PJAR formation, and cell death. As further validation, overexpression of Rac GTPase-activating protein beta(2)-chimerin also preserved monolayer barrier properties in stretched monolayers. In summary, our data suggest that constitutive activity of Rac1, which is necessary for stretch-induced activation of the Rac1 downstream proteins, mediates stretch-induced increases in permeability and PJAR formation.