Pertz Olivier, Hodgson Louis, Klemke Richard L, Hahn Klaus M
University of North Carolina at Chapel Hill, Department of Pharmacology and Lineberger Cancer Center, Chapel Hill, North Carolina 27599, USA.
Nature. 2006 Apr 20;440(7087):1069-72. doi: 10.1038/nature04665. Epub 2006 Mar 19.
Rho family GTPases regulate the actin and adhesion dynamics that control cell migration. Current models postulate that Rac promotes membrane protrusion at the leading edge and that RhoA regulates contractility in the cell body. However, there is evidence that RhoA also regulates membrane protrusion. Here we use a fluorescent biosensor, based on a novel design preserving reversible membrane interactions, to visualize the spatiotemporal dynamics of RhoA activity during cell migration. In randomly migrating cells, RhoA activity is concentrated in a sharp band directly at the edge of protrusions. It is observed sporadically in retracting tails, and is low in the cell body. RhoA activity is also associated with peripheral ruffles and pinocytic vesicles, but not with dorsal ruffles induced by platelet-derived growth factor (PDGF). In contrast to randomly migrating cells, PDGF-induced membrane protrusions have low RhoA activity, potentially because PDGF strongly activates Rac, which has previously been shown to antagonize RhoA activity. Our data therefore show that different extracellular cues induce distinct patterns of RhoA signalling during membrane protrusion.
Rho家族GTP酶调节控制细胞迁移的肌动蛋白和黏附动力学。目前的模型推测，Rac促进前沿的膜突出，而RhoA调节细胞体的收缩性。然而，有证据表明RhoA也调节膜突出。在这里，我们使用一种基于新型设计的荧光生物传感器，该设计保留了可逆的膜相互作用，以可视化细胞迁移过程中RhoA活性的时空动态。在随机迁移的细胞中，RhoA活性集中在突起边缘的一条清晰条带中。在回缩尾部偶尔观察到，而在细胞体中较低。RhoA活性也与外周微褶和胞饮小泡相关，但与血小板衍生生长因子（PDGF）诱导的背侧微褶无关。与随机迁移的细胞相反，PDGF诱导的膜突出具有低RhoA活性，这可能是因为PDGF强烈激活Rac，而Rac先前已被证明可拮抗RhoA活性。因此，我们的数据表明，不同的细胞外信号在膜突出过程中诱导不同的RhoA信号模式。
