Division of Diabetes, Metabolism, and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan; and.
Division of Diabetes, Metabolism, and Endocrinology, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan; and
Am J Physiol Renal Physiol. 2014 Sep 1;307(5):F571-80. doi: 10.1152/ajprenal.00113.2014. Epub 2014 Jul 9.
The small GTPase Rho and its downstream effector, Rho-associated coiled-coil containing protein kinase (Rho-kinase), regulate a number of cellular processes, including organization of the actin cytoskeleton, cell adhesion, and migration. While pharmacological inhibitors of Rho-kinase signaling are known to block renal inflammation, the molecular basis for this effect is unclear. Here, we provide evidence that proinflammatory TNF-α promotes mesangial expression of macrophage colony-stimulating factor (M-CSF), a key regulator for the growth and differentiation of mononuclear phagocytes, in a Rho-kinase-dependent manner. Consistent with this observation, TNF-α-mediated renal expression of M-CSF in insulin-resistant db/db mice was downregulated by Rho-kinase inhibition. Small interfering RNA-facilitated knockdown of Rho-kinase isoforms ROCK1 and ROCK2 indicated that both isoforms make comparable contributions to regulation of M-CSF expression in mesangial cells. From a mechanistic standpoint, Western blotting and EMSA showed that Rho-kinase and its downstream target p38 MAPK regulate nuclear translocation of NF-κB RelA/p65 and subsequent DNA binding activity, with no significant effects on IκBα degradation and RelA/p65 phosphorylation. Moreover, we showed that Rho-kinase-mediated cytoskeletal organization is required for the nuclear uptake of RelA/p65. Collectively, these findings identify Rho-kinase as a critical regulator of chemokine expression and macrophage proliferation.
小分子 GTPase Rho 及其下游效应物 Rho 相关卷曲螺旋蛋白激酶（Rho-kinase）调节许多细胞过程，包括肌动蛋白细胞骨架的组织、细胞黏附以及迁移。尽管 Rho-kinase 信号通路的药理学抑制剂已被证实可阻断肾脏炎症，但该效应的分子基础尚不清楚。在这里，我们提供的证据表明，促炎细胞因子 TNF-α以 Rho-kinase 依赖性方式促进肾小球系膜细胞中巨噬细胞集落刺激因子（M-CSF）的表达，M-CSF 是单核吞噬细胞生长和分化的关键调节剂。与这一观察结果一致的是，Rho-kinase 抑制剂可下调胰岛素抵抗的 db/db 小鼠中 TNF-α介导的肾脏 M-CSF 表达。通过小干扰 RNA 促进 Rho-kinase 同工型 ROCK1 和 ROCK2 的敲低表明，两种同工型在调节系膜细胞中 M-CSF 表达方面具有相当的作用。从机制上讲，Western blot 和 EMSA 表明 Rho-kinase 和其下游靶标 p38 MAPK 调节 NF-κB RelA/p65 的核易位和随后的 DNA 结合活性，对 IκBα降解和 RelA/p65 磷酸化没有明显影响。此外，我们表明 Rho-kinase 介导的细胞骨架组织对于 RelA/p65 的核摄取是必需的。总之，这些发现表明 Rho-kinase 是趋化因子表达和巨噬细胞增殖的关键调节剂。
