TY - JOUR
T1 - Rac activation by lysophosphatidic acid LPA1 receptors through the guanine nucleotide exchange factor Tiam1
AU - Van Leeuwen, Frank N
AU - Olivo, Cristina
AU - Grivell, Shula
AU - Giepmans, Ben N G
AU - Collard, John G
AU - Moolenaar, Wouter H
PY - 2003/1/3
Y1 - 2003/1/3
N2 - Lysophosphatidic acid (LPA) is a serum-borne phospholipid that activates its own G protein-coupled receptors present in numerous cell types. In addition to stimulating cell proliferation, LPA also induces cytoskeletal changes and promotes cell migration in a RhoA- and Rac-dependent manner. Whereas RhoA is activated via Galpha(12/13)-linked Rho-specific guanine nucleotide exchange factors, it is unknown how LPA receptors may signal to Rac. Here we report that the prototypic LPA(1) receptor (previously named Edg2), when expressed in B103 neuroblastoma cells, mediates transient activation of RhoA and robust, prolonged activation of Rac leading to cell spreading, lamellipodia formation, and stimulation of cell migration. LPA-induced Rac activation is inhibited by pertussis toxin and requires phosphoinositide 3-kinase activity. Strikingly, LPA fails to activate Rac in cell types that lack the Rac-specific exchange factor Tiam1; however, enforced expression of Tiam1 restores LPA-induced Rac activation in those cells. Tiam1-deficient cells show enhanced RhoA activation, stress fiber formation, and cell rounding in response to LPA, consistent with Tiam1/Rac counteracting RhoA. We conclude that LPA(1) receptors couple to a G(i)-phosphoinositide 3-kinase-Tiam1 pathway to activate Rac, with consequent suppression of RhoA activity, and thereby stimulate cell spreading and motility.
AB - Lysophosphatidic acid (LPA) is a serum-borne phospholipid that activates its own G protein-coupled receptors present in numerous cell types. In addition to stimulating cell proliferation, LPA also induces cytoskeletal changes and promotes cell migration in a RhoA- and Rac-dependent manner. Whereas RhoA is activated via Galpha(12/13)-linked Rho-specific guanine nucleotide exchange factors, it is unknown how LPA receptors may signal to Rac. Here we report that the prototypic LPA(1) receptor (previously named Edg2), when expressed in B103 neuroblastoma cells, mediates transient activation of RhoA and robust, prolonged activation of Rac leading to cell spreading, lamellipodia formation, and stimulation of cell migration. LPA-induced Rac activation is inhibited by pertussis toxin and requires phosphoinositide 3-kinase activity. Strikingly, LPA fails to activate Rac in cell types that lack the Rac-specific exchange factor Tiam1; however, enforced expression of Tiam1 restores LPA-induced Rac activation in those cells. Tiam1-deficient cells show enhanced RhoA activation, stress fiber formation, and cell rounding in response to LPA, consistent with Tiam1/Rac counteracting RhoA. We conclude that LPA(1) receptors couple to a G(i)-phosphoinositide 3-kinase-Tiam1 pathway to activate Rac, with consequent suppression of RhoA activity, and thereby stimulate cell spreading and motility.
KW - Androstadienes/metabolism
KW - Animals
KW - COS Cells
KW - Cell Movement/physiology
KW - Cell Size
KW - Culture Media, Serum-Free
KW - Fibroblasts/cytology
KW - Guanine Nucleotide Exchange Factors/metabolism
KW - Humans
KW - Insulin/metabolism
KW - Lysophospholipids/metabolism
KW - Mice
KW - Mice, Knockout
KW - Pertussis Toxin/metabolism
KW - Proteins/genetics
KW - Receptors, Cell Surface/genetics
KW - Receptors, G-Protein-Coupled
KW - Receptors, Lysophosphatidic Acid
KW - Signal Transduction/physiology
KW - T-Lymphoma Invasion and Metastasis-inducing Protein 1
KW - Tumor Cells, Cultured
KW - Wortmannin
KW - rac GTP-Binding Proteins/metabolism
KW - rho GTP-Binding Proteins/metabolism
UR - http://www.scopus.com/inward/record.url?scp=0347520943&partnerID=8YFLogxK
U2 - 10.1074/jbc.M210151200
DO - 10.1074/jbc.M210151200
M3 - Article
C2 - 12393875
SN - 0021-9258
VL - 278
SP - 400
EP - 406
JO - The Journal of biological chemistry
JF - The Journal of biological chemistry
IS - 1
ER -