RhoA GTPase Is Dispensable for Actomyosin Regulation but Is Essential for Mitosis in Primary Mouse Embryonic Fibroblasts
RhoA GTPase Is Dispensable for Actomyosin Regulation but Is Essential for Mitosis in Primary Mouse Embryonic Fibroblasts
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DOI：
10.1074/jbc.c111.229336
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发表时间：
2011-04-29
影响因子：
4.8
通讯作者：
Zheng, Yi
中科院分区：
文献类型：
--
作者：
Melendez, Jaime;Stengel, Kristy;Zheng, Yi
RhoA是哺乳动物Rho GT3家族的创始成员，被认为是肌动球蛋白调节所必需的。迄今为止，RhoA在哺乳动物细胞调节中的生理功能尚未在遗传上确定。在这里，我们已经创建了RhoA条件性敲除小鼠。缺失RhoA的小鼠胚胎成纤维细胞对血清或LPA的反应中肌动蛋白应力纤维或粘着斑复合物的形成没有显着变化，Rho激酶信号活性也没有任何可检测到的变化。同时敲除或敲低RhoA（-/-）细胞中的RhoB和RhoC导致肌动蛋白应力纤维的损失和与C3毒素处理类似的粘着斑。RhoA（-/-）细胞的增殖由于有丝分裂期间的完全细胞周期阻滞而受损，该效应与有缺陷的胞质分裂和染色体分离相关，并且可以通过RhoA的外源性表达容易地挽救。此外，RhoA缺失不影响Stat 3、NF κ B B或血清反应因子的转录活性，也不影响细胞分裂激酶抑制剂p21（Cip）1或p27（Kip 1）的表达。这些遗传结果表明，在原代小鼠胚胎成纤维细胞，RhoA是唯一需要的细胞有丝分裂，但与相关的RhoB和RhoC GTP酶在肌动球蛋白调节是多余的。
RhoA, the founding member of mammalian Rho GTPase family, is thought to be essential for actomyosin regulation. To date, the physiologic function of RhoA in mammalian cell regulation has yet to be determined genetically. Here we have created RhoA conditional knock-out mice. Mouse embryonic fibroblasts deleted of RhoA showed no significant change in actin stress fiber or focal adhesion complex formation in response to serum or LPA, nor any detectable change in Rho-kinase signaling activity. Concomitant knock-out or knockdown of RhoB and RhoC in the RhoA(-/-) cells resulted in a loss of actin stress fiber and focal adhesion similar to that of C3 toxin treatment. Proliferation of RhoA(-/-) cells was impaired due to a complete cell cycle block during mitosis, an effect that is associated with defective cytokinesis and chromosome segregation and can be readily rescued by exogenous expression of RhoA. Furthermore, RhoA deletion did not affect the transcriptional activity of Stat3, NF kappa B, or serum response factor, nor the expression of the cell division kinase inhibitor p21(Cip)1 or p27(Kip1). These genetic results demonstrate that in primary mouse embryonic fibroblasts, RhoA is uniquely required for cell mitosis but is redundant with related RhoB and RhoC GTPases in actomyosin regulation.