Pitx2a expression alters actin-myosin cytoskeleton and migration of HeLa cells through Rho GTPase signaling.
Pitx2a expression alters actin-myosin cytoskeleton and migration of HeLa cells through Rho GTPase signaling.
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Pitx2a 表达通过 Rho GTPase 信号传导改变肌动蛋白-肌球蛋白细胞骨架和 HeLa 细胞的迁移。
DOI：
10.1091/mbc.01-07-0358
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发表时间：
2002
影响因子：
3.3
通讯作者：
Adelstein,RobertS
中科院分区：
文献类型：
--
作者：
Wei,Qize;Adelstein,RobertS
我们使用四环素诱导表达系统在 HeLa 细胞中异位表达转录因子 Pitx2a（Pitx2 亚型之一），并检查 Pitx2a 是否能够调节 Rho GTPase 信号传导并改变细胞的细胞骨架。 Pitx2a 的异位表达诱导肌动蛋白-肌球蛋白重组，导致细胞铺展增加、细胞迁移抑制和细胞-细胞粘附增强，其标志是 β-连环蛋白和 N-钙粘蛋白在细胞-细胞接触部位的积累和定位。此外，Pitx2a 表达导致 Rho GTPases Rac1 和 RhoA 的激活，显性失活 Rac1 突变体 N17Rac1 抑制细胞扩散并破坏 β-连环蛋白在细胞与细胞接触部位的定位。肌动蛋白-肌球蛋白的重组和细胞扩散都需要磷脂酰肌醇 3 激酶活性，这对于 Rho GTP 酶蛋白的激活也是必需的。 Pitx2a在细胞铺展之前诱导Trio（Rac1和RhoA的鸟嘌呤核苷酸交换因子）的表达，并且在细胞铺展和细胞形态发生变化后Trio蛋白的表达下调。此外，Pitx2a 还诱导细胞周期停滞在 G0/G1，这很可能是由于肿瘤抑制蛋白 p53 和 p21 的积累所致。我们的数据表明，Pitx2a 在细胞核中启动的转录活动导致 HeLa 细胞形态、迁移和增殖的深刻变化。
We ectopically expressed the transcription factor Pitx2a, one of the Pitx2 isoforms, in HeLa cells by using a tetracycline-inducible expression system and examined whether Pitx2a was capable of modulating Rho GTPase signaling and altering the cell's cytoskeleton. Ectopic expression of Pitx2a induced actin-myosin reorganization, leading to increased cell spreading, suppression of cell migration, and the strengthening of cell-cell adhesion, marked by the accumulation and localization of β-catenin and N-cadherin to the sites of cell-cell contacts. Moreover, Pitx2a expression resulted in activation of the Rho GTPases Rac1 and RhoA, and the dominant negative Rac1 mutant N17Rac1 inhibited cell spreading and disrupted localization of β-catenin to the sites of cell-cell contacts. Both reorganization of actin-myosin and cell spreading require phosphatidylinositol 3-kinase activity, which is also necessary for activation of the Rho GTPase proteins. Pitx2a induced the expression of Trio, a guanine nucleotide exchange factor for Rac1 and RhoA, which preceded cell spreading, and the expression of Trio protein was down-regulated after the changes in cell spreading and cell morphology were initiated. In addition, Pitx2a also induces cell cycle arrest at G0/G1, most likely due to the accumulation of the tumor suppressor proteins p53 and p21. Our data indicate that the transcriptional activities initiated in the nucleus by Pitx2a result in profound changes in HeLa cell morphology, migration, and proliferation.