RRC ID 39633
Author Okamoto H, Takuwa N, Yokomizo T, Sugimoto N, Sakurada S, Shigematsu H, Takuwa Y.
Title Inhibitory regulation of Rac activation, membrane ruffling, and cell migration by the G protein-coupled sphingosine-1-phosphate receptor EDG5 but not EDG1 or EDG3.
Journal Mol Cell Biol
Abstract Sphingosine-1-phosphate (S1P) is a bioactive lysophospholipid that induces a variety of biological responses in diverse cell types. Many, if not all, of these responses are mediated by members of the EDG (endothelial differentiation gene) family G protein-coupled receptors EDG1, EDG3, and EDG5 (AGR16). Among prominent activities of S1P is the regulation of cell motility; S1P stimulates or inhibits cell motility depending on cell types. In the present study, we provide evidence for EDG subtype-specific, contrasting regulation of cell motility and cellular Rac activity. In CHO cells expressing EDG1 or EDG3 (EDG1 cells or EDG3 cells, respectively) S1P as well as insulin-like growth factor I (IGF I) induced chemotaxis and membrane ruffling in phosphoinositide (PI) 3-kinase- and Rac-dependent manners. Both S1P and IGF I induced a biphasic increase in the amount of the GTP-bound active form of Rac. In CHO cells expressing EDG5 (EDG5 cells), IGF I similarly stimulated cell migration; however, in contrast to what was found for EDG1 and EDG3 cells, S1P did not stimulate migration but totally abolished IGF I-directed chemotaxis and membrane ruffling, in a manner dependent on a concentration gradient of S1P. In EDG5 cells, S1P stimulated PI 3-kinase activity as it did in EDG1 cells but inhibited the basal Rac activity and totally abolished IGF I-induced Rac activation, which involved stimulation of Rac-GTPase-activating protein activity rather than inhibition of Rac-guanine nucleotide exchange activity. S1P induced comparable increases in the amounts of GTP-RhoA in EDG3 and EDG5 cells. Neither S1P nor IGF I increased the amount of GTP-bound Cdc42. However, expression of N(17)-Cdc42, but not N(19)-RhoA, suppressed S1P- and IGF I-directed chemotaxis, suggesting a requirement for basal Cdc42 activity for chemotaxis. Taken together, the present results demonstrate that EDG5 is the first example of a hitherto-unrecognized type of receptors that negatively regulate Rac activity, thereby inhibiting cell migration and membrane ruffling.
Volume 20(24)
Pages 9247-61
Published 2000-12-1
DOI 10.1128/mcb.20.24.9247-9261.2000
PMID 11094076
PMC PMC102182
MeSH 3T3 Cells Animals CHO Cells Cell Membrane / metabolism* Cell Membrane / ultrastructure Chemotaxis / drug effects* Cricetinae DNA-Binding Proteins / metabolism Humans I-kappa B Proteins* Immediate-Early Proteins / metabolism Insulin-Like Growth Factor I / pharmacology Lysophospholipids* Mice NF-KappaB Inhibitor alpha Phosphatidylinositol 3-Kinases / metabolism Protein Isoforms / metabolism Protein Kinase Inhibitors Protein-Serine-Threonine Kinases / metabolism Receptors, Cell Surface / metabolism* Receptors, G-Protein-Coupled* Receptors, Lysophospholipid Recombinant Proteins / genetics Recombinant Proteins / metabolism Signal Transduction* Sphingosine / analogs & derivatives* Sphingosine / metabolism Sphingosine / pharmacology* Stress Fibers / metabolism Transfection cdc42 GTP-Binding Protein / metabolism p21-Activated Kinases rac GTP-Binding Proteins / antagonists & inhibitors* rac GTP-Binding Proteins / metabolism rho GTP-Binding Proteins / metabolism
IF 3.735
Times Cited 272
Human and Animal Cells