Hyperosmotic stress induces Rho/Rho kinase/LIM kinase-mediated cofilin phosphorylation in tubular cells: key role in the osmotically triggered F-actin response
Hyperosmotic stress induces Rho/Rho kinase/LIM kinase-mediated cofilin phosphorylation in tubular cells: key role in the osmotically triggered F-actin response
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DOI：
10.1152/ajpcell.00467.2008
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发表时间：
2009-03-01
影响因子：
5.5
通讯作者：
Kapus, Andras
中科院分区：
文献类型：
--
作者：
Thirone, Ana C. P.;Speight, Pam;Kapus, Andras
王晓明，王晓明，王晓明，等。高渗应激诱导肾小管细胞中Rho/Rho激酶/LIM激酶介导的cofilin磷酸化的研究进展。[J] .中国生物医学工程学报，2009,31(6):563 - 567。首次发表于2008年12月24日；doi: 10.1152 / ajpcell.00467.2008。-高渗应激诱导细胞骨架重组和细胞f -肌动蛋白的净增加，但其潜在机制尚不完全清楚。尽管从头开始的f -肌动蛋白聚合可能有助于肌动蛋白反应，但f -肌动蛋白切断的作用尚不清楚。为了解决这个问题，我们研究了高渗透压是否调节cofilin，一个关键的肌动蛋白切断蛋白，其活性被磷酸化抑制。由于小gtpase Rho和Rac对细胞体积变化敏感，并且可以调节cofilin的磷酸化，我们也想知道它们是否可能将渗透胁迫与cofilin联系起来。本研究表明，高渗透压诱导肾小管细胞（LLC-PK1和Madin-Darby犬肾）中cofilin的快速、持续和可逆磷酸化。高渗透压诱导的cofilin磷酸化是由Rho/Rho激酶（ROCK)/LIM激酶（LIMK）介导的，而不是Rac/PAK/LIMK途径，因为1）显性阴性（DN） Rho和DN-ROCK而不是DN-Rac和DN-PAK抑制cofilin磷酸化；2)组成型活性（CA） Rho和CA- rock诱导的cofilin磷酸化，而CA- rac和CA- pak诱导的cofilin磷酸化不起作用；3)高渗诱导LIMK-2磷酸化，4)Y-27632抑制ROCK抑制高渗引发的LIMK-2和cofilin磷酸化。然后，我们研究了cofilin及其磷酸化是否在高渗性引发的f -肌动蛋白变化中发挥作用。小干扰RNA对cofilin的下调增加了静息f -肌动蛋白水平，并消除了高渗治疗后的进一步升高。Y-27632抑制cofilin磷酸化可阻止高渗透压引起的f -肌动蛋白升高。综上所述，在小管细胞中，cofilin对于维持细胞骨架的渗透反应是必要的，Rho/ROCK/ limk介导的cofilin磷酸化是高渗应激诱导的f -肌动蛋白增加的关键机制。
Thirone AC, Speight P, Zulys M, Rotstein OD, Szaszi K, Pedersen SF, Kapus A. Hyperosmotic stress induces Rho/Rho kinase/LIM kinase-mediated cofilin phosphorylation in tubular cells: key role in the osmotically triggered F-actin response. Am J Physiol Cell Physiol 296: C463-C475, 2009. First published December 24, 2008; doi:10.1152/ajpcell.00467.2008.-Hyperosmotic stress induces cytoskeleton reorganization and a net increase in cellular F-actin, but the underlying mechanisms are incompletely understood. Whereas de novo F-actin polymerization likely contributes to the actin response, the role of F-actin severing is unknown. To address this problem, we investigated whether hyperosmolarity regulates cofilin, a key actin-severing protein, the activity of which is inhibited by phosphorylation. Since the small GTPases Rho and Rac are sensitive to cell volume changes and can regulate cofilin phosphorylation, we also asked whether they might link osmostress to cofilin. Here we show that hyperosmolarity induced rapid, sustained, and reversible phosphorylation of cofilin in kidney tubular (LLC-PK1 and Madin-Darby canine kidney) cells. Hyperosmolarity-provoked cofilin phosphorylation was mediated by the Rho/Rho kinase (ROCK)/LIM kinase (LIMK) but not the Rac/PAK/LIMK pathway, because 1) dominant negative (DN) Rho and DN-ROCK but not DN-Rac and DN-PAK inhibited cofilin phosphorylation; 2) constitutively active (CA) Rho and CA-ROCK but not CA-Rac and CA-PAK induced cofilin phosphorylation; 3) hyperosmolarity induced LIMK-2 phosphorylation, and 4) inhibition of ROCK by Y-27632 suppressed the hypertonicity-triggered LIMK-2 and cofilin phosphorylation. We thenexamined whether cofilin and its phosphorylation play a role in the hypertonicity-triggered F-actin changes. Downregulation of cofilin by small interfering RNA increased the resting F-actin level and eliminated any further rise upon hypertonic treatment. Inhibition of cofilin phosphorylation by Y-27632 prevented the hyperosmolarity-provoked F-actin increase. Taken together, cofilin is necessary for maintaining the osmotic responsiveness of the cytoskeleton in tubular cells, and the Rho/ROCK/LIMK-mediated cofilin phosphorylation is a key mechanism in the hyperosmotic stress-induced F-actin increase.