title: Direct interaction of p21-activated kinase 4 with PDZ-RhoGEF, a G protein-linked Rho guanine exchange factor.
abstract: Rho GTPases regulate a wide variety of cellular processes, ranging from actin cytoskeleton remodeling to cell cycle progression and gene expression. Cell surface receptors act through a complex regulatory molecular network that includes guanine exchange factors (GEFs), GTPase activating proteins, and guanine dissociation inhibitors to achieve the coordinated activation and deactivation of Rho proteins, thereby controlling cell motility and ultimately cell fate. Here we found that a member of the RGL-containing family of Rho guanine exchange factors, PDZ RhoGEF, which, together with LARG and p115RhoGEF, links the G(12/13) family of heterotrimeric G proteins to Rho activation, binds through its C-terminal region to the serine-threonine kinase p21-activated kinase 4 (PAK4), an effector for Cdc42. This interaction results in the phosphorylation of PDZ RhoGEF and abolishes its ability to mediate the accumulation of Rho-GTP by Galpha13. Moreover, when overexpressed, active PAK4 was able to dramatically decrease Rho-GTP loading in vivo and the formation of actin stress fibers in response to serum or LPA stimulation. Together, these results provide evidence that PAK4 can negatively regulate the activation of Rho through a direct protein-protein interaction with G protein-linked Rho GEFs, thus providing a novel potential mechanism for cross-talk among Rho GTPases.
authors: Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892-4330, USA.
authors: Ana
authors: A
authors: Barac
authors: John
authors: J
authors: Basile
authors: José
authors: J
authors: Vázquez-Prado
authors: Yuan
authors: Y
authors: Gao
authors: Yi
authors: Y
authors: Zheng
authors: J Silvio
authors: JS
authors: Gutkind
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D004789:Enzyme Activation; D005982:Glutathione Transferase / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D051379:Mice; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D010802:Phylogeny; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017470:Receptors, Glutamate / Q000737:chemistry / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors; D013997:Time Factors; D014162:Transfection; D020798:Two-Hybrid System Techniques; D054462:p21-Activated Kinases
chemical_list: C577234:ARHGEF11 protein, human; D020662:Guanine Nucleotide Exchange Factors; D017470:Receptors, Glutamate; D011993:Recombinant Fusion Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; D005982:Glutathione Transferase; C116367:PAK4 protein, human; C492065:Pak4 protein, mouse; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases