Gebbink M F, Kranenburg O, Poland M, van Horck F P, Houssa B, Moolenaar W H
Division of Cellular Biochemistry, The Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands.
J Cell Biol. 1997 Jun 30;137(7):1603-13. doi: 10.1083/jcb.137.7.1603.
The small GTP-binding protein Rho has been implicated in the control of neuronal morphology. In N1E-115 neuronal cells, the Rho-inactivating C3 toxin stimulates neurite outgrowth and prevents actomyosin-based neurite retraction and cell rounding induced by lysophosphatidic acid (LPA), sphingosine-1-phosphate, or thrombin acting on their cognate G protein-coupled receptors. We have identified a novel putative GDP/GTP exchange factor, RhoGEF (190 kD), that interacts with both wild-type and activated RhoA, but not with Rac or Cdc42. RhoGEF, like activated RhoA, mimics receptor stimulation in inducing cell rounding and in preventing neurite outgrowth. Furthermore, we have identified a 116-kD protein, p116(Rip), that interacts with both the GDP- and GTP-bound forms of RhoA in N1E-115 cells. Overexpression of p116(Rip) stimulates cell flattening and neurite outgrowth in a similar way to dominant-negative RhoA and C3 toxin. Cells overexpressing p116(Rip) fail to change their shape in response to LPA, as is observed after Rho inactivation. Our results indicate that (a) RhoGEF may link G protein-coupled receptors to RhoA activation and ensuing neurite retraction and cell rounding; and (b) p116(Rip) inhibits RhoA-stimulated contractility and promotes neurite outgrowth.
小GTP结合蛋白Rho与神经元形态的控制有关。在N1E-115神经元细胞中，Rho失活的C3毒素可刺激神经突生长，并防止溶血磷脂酸（LPA）、鞘氨醇-1-磷酸或凝血酶作用于其相应的G蛋白偶联受体所诱导的基于肌动球蛋白的神经突回缩和细胞变圆。我们鉴定出一种新的假定GDP/GTP交换因子RhoGEF（190 kD），它可与野生型和活化的RhoA相互作用，但不与Rac或Cdc42相互作用。RhoGEF与活化的RhoA一样，在诱导细胞变圆和防止神经突生长方面模拟受体刺激。此外，我们鉴定出一种116-kD的蛋白p116(Rip)，它可与N1E-115细胞中GDP结合形式和GTP结合形式的RhoA相互作用。p116(Rip)的过表达以与显性负性RhoA和C3毒素类似的方式刺激细胞扁平化和神经突生长。过表达p116(Rip)的细胞在Rho失活后观察到的那样，对LPA没有形状变化反应。我们的结果表明：（a）RhoGEF可能将G蛋白偶联受体与RhoA激活以及随后的神经突回缩和细胞变圆联系起来；（b）p116(Rip)抑制RhoA刺激的收缩性并促进神经突生长。
