title: Inhibitory and stimulatory regulation of Rac and cell motility by the G12/13-Rho and Gi pathways integrated downstream of a single G protein-coupled sphingosine-1-phosphate receptor isoform.
abstract: The G protein-coupled receptors S1P2/Edg5 and S1P3/Edg3 both mediate sphingosine-1-phosphate (S1P) stimulation of Rho, yet S1P2 but not S1P3 mediates downregulation of Rac activation, membrane ruffling, and cell migration in response to chemoattractants. Specific inhibition of endogenous Galpha12 and Galpha13, but not of Galphaq, by expression of respective C-terminal peptides abolished S1P2-mediated inhibition of Rac, membrane ruffling, and migration, as well as stimulation of Rho and stress fiber formation. Fusion receptors comprising S1P2 and either Galpha12 or Galpha13, but not Galphaq, mediated S1P stimulation of Rho and also inhibition of Rac and migration. Overexpression of Galphai, by contrast, specifically antagonized S1P2-mediated inhibition of Rac and migration. The S1P2 actions were mimicked by expression of V14Rho and were abolished by C3 toxin and N19Rho, but not Rho kinase inhibitors. In contrast to S1P2, S1P3 mediated S1P-directed, pertussis toxin-sensitive chemotaxis and Rac activation despite concurrent stimulation of Rho via G12/13. Upon inactivation of Gi by pertussis toxin, S1P3 mediated inhibition of Rac and migration just like S1P2. These results indicate that integration of counteracting signals from the Gi- and the G12/13-Rho pathways directs either positive or negative regulation of Rac, and thus cell migration, upon activation of a single S1P receptor isoform.
authors.affiliation: Department of Physiology, Kanazawa University Graduate School of Medicine, Kanazawa, Ishikawa 920-8640, Japan.
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Sugimoto
authors.forename: Noriko
authors.initials: N
authors.lastname: Takuwa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okamoto
authors.forename: Sotaro
authors.initials: S
authors.lastname: Sakurada
authors.forename: Yoh
authors.initials: Y
authors.lastname: Takuwa
mesh_terms: D016475:3T3 Cells; D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D001905:Botulinum Toxins / Q000378:metabolism; D016466:CHO Cells; D019556:COS Cells; D002465:Cell Movement; D002633:Chemotaxis; D006224:Cricetinae; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D010455:Peptides / Q000737:chemistry; D037342:Pertussis Toxin / Q000494:pharmacology; D010957:Plasmids / Q000378:metabolism; D020033:Protein Isoforms; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D016895:Culture Media, Serum-Free; D010455:Peptides; D020033:Protein Isoforms; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; D011993:Recombinant Fusion Proteins; D037342:Pertussis Toxin; D001905:Botulinum Toxins; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins