Heterotrimeric G protein betagamma subunits stimulate FLJ00018, a guanine nucleotide exchange factor for Rac1 and Cdc42.
We previously reported that Gbetagamma signaling regulates cell spreading or cell shape change through activation of a Rho family small GTPase, suggesting the existence of a Gbetagamma-regulated Rho guanine-nucleotide exchange factor (RhoGEF). In this study we examined various RhoGEF clones, found FLJ00018 to beaGbetagamma-activated RhoGEF, and investigated the molecular mechanism of Gbetagamma-induced activation of Rho family GTPases. Co-expression of the genes for FLJ00018 and Gbetagamma enhanced serum response element-mediated gene transcription in HEK-293 cells. Combined expression of Gbetagamma and FLJ00018 significantly induced activation of Rac and Cdc42 but not RhoA. FLJ00018 also enhanced gene transcription induced by carbachol-stimulated m2 muscarinic acetylcholine receptor, and this enhancement was blocked by pertussis toxin. Furthermore, we demonstrated Gbetagamma to interact directly with the N-terminal region of FLJ00018 and the N-terminal fragment of this molecule to inhibit serum response element-dependent transcription induced by Gbetagamma/FLJ00018 and carbachol. In NIH3T3 cells, FLJ00018 enhanced lysophosphatidic acid-induced cell spreading, which was also blocked by the N-terminal fragment of FLJ00018. These results provide evidence for a signaling pathway by which G(i)-coupled receptor specifically induces Rac and Cdc42 activation through direct interaction of Gbetagamma with FLJ00018.
Department of Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido 1-1, Gifu 501-1193, Japan. hueda@gifu-u.ac.jp
Hiroshi
H
Ueda
Rika
R
Nagae
Mika
M
Kozawa
Rika
R
Morishita
Shinji
S
Kimura
Takahiro
T
Nagase
Osamu
O
Ohara
Satoshi
S
Yoshida
Tomiko
T
Asano
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D048430:Cell Shape / Q000502:physiology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D015870:Gene Expression; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism*; D037342:Pertussis Toxin / Q000494:pharmacology; D043585:Receptor, Muscarinic M2 / Q000235:genetics / Q000378:metabolism; D027602:Serum Response Element / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D018679:Cholinergic Agonists; D020662:Guanine Nucleotide Exchange Factors; D008246:Lysophospholipids; D009479:Neuropeptides; C527535:PLEKHG2 protein, human; C107953:RAC1 protein, human; C484602:Rac1 protein, mouse; D043585:Receptor, Muscarinic M2; C066737:RHOA protein, human; D002217:Carbachol; D037342:Pertussis Toxin; D020962:Heterotrimeric GTP-Binding Proteins; C526380:RhoA protein, mouse; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; C032881:lysophosphatidic acid