title: Src kinase regulates the activation of a novel FGD-1-related Cdc42 guanine nucleotide exchange factor in the signaling pathway from the endothelin A receptor to JNK.
abstract: Small GTPases act as binary switches by cycling between an inactive (GDP-bound) and an active (GTP-bound) state. Upon stimulation with extracellular signals, guanine-nucleotide exchange factors (GEFs) stimulate the exchange of GDP to GTP to shift toward the active forms of small GTPases, recognizing the downstream targets. Here we show that KIAA0793, containing substantial sequence homology with the catalytic Dbl homology domain of the faciogenital dysplasia gene product (FGD1), is a specific GEF for Cdc42. We, therefore, tentatively named it FRG (FGD1-related Cdc42-GEF). Src kinase directly phosphorylates and activates FRG, as Vav family GEFs. Additionally, FRG is involved in the signaling pathway from the endothelin A receptor to c-Jun N-terminal kinase, resulting in the inhibition of cell motility. These results suggest that FRG is a member of Cdc42-GEF and plays an important role in the signaling pathway downstream of G protein-coupled receptors.
authors.affiliation: Department of Cell Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Miyamoto
authors.forename: Junji
authors.initials: J
authors.lastname: Yamauchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Itoh
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D002460:Cell Line; D002465:Cell Movement; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000378:metabolism; D019332:Endothelin-1 / Q000378:metabolism; D016232:Endothelins / Q000378:metabolism; D004789:Enzyme Activation; D005799:Genes, Dominant; D005982:Glutathione Transferase / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry* / Q000502:physiology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D044022:Receptor, Endothelin A; D017466:Receptors, Endothelin / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D019061:src-Family Kinases / Q000502:physiology*
chemical_list: D018076:DNA, Complementary; D019332:Endothelin-1; D016232:Endothelins; C490796:FGD1 protein, human; C477286:FGD1-related Cdc42-GEF protein, human; D020662:Guanine Nucleotide Exchange Factors; D011506:Proteins; D044022:Receptor, Endothelin A; D017466:Receptors, Endothelin; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D014443:Tyrosine; D011392:Proline; D005982:Glutathione Transferase; D019061:src-Family Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein