title: Heterotrimeric G protein Gαs subunit attenuates PLEKHG2, a Rho family-specific guanine nucleotide exchange factor, by direct interaction.
abstract: PLEKHG2 is a Gβγ-dependent guanine nucleotide exchange factor (GEF) for the small GTPases Rac and Cdc42, and has been shown to mediate signalling pathways such as actin cytoskeleton reorganization and serum response element (SRE)-dependent gene transcription. Here we show that the constitutively active mutant of the Gαs subunit significantly attenuated PLEKHG2-induced SRE-mediated gene transcription. Strikingly, we observed that the constitutive activation of endogenous Gαs by treatment with CTx caused a similar inhibitory effect on PLEKHG2-induced activation of SRE. However, both the enforced expression of the catalytic subunit β of protein kinase A and the treatment with dibutyl-cyclic AMP failed to mimic the inhibitory effect of Gαs on PLEKHG2. Furthermore, the dominant negative mutant of protein kinase A had no effect on PLEKHG2-mediated SRE activation. Performing immunoprecipitation and an in vitro pulldown assay, we found that PLEKHG2 directly interacted with the active form of the Gαs subunit in cells. The interaction between PLEKHG2 and Gαs required the N-terminal region of PLEKHG2, which includes the DH domain, a functional domain of GEF, suggesting that Gαs directly masks the DH domain of PLEKHG2. In a previous study, we reported that Gβγ accelerates PLEKHG2-mediated SRE-dependent gene transcription. Interestingly, Gαs also inhibited the hyperactivation of SRE induced by the co-expression of Gβγ and PLEKHG2; however, Gαs and Gβγ bind to different regions of PLEKHG2. This is the first report to show that PLEKHG2 is a novel effector of Gαs, and is negatively regulated by the Gαs subunit through direct interaction.
authors.affiliation: United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Yanagido1-1, Gifu 501-1193, Japan.
authors.forename: Kazue
authors.initials: K
authors.lastname: Sugiyama
authors.affiliation: Graduate School of Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tago
authors.affiliation: Department of Functional Bioscience, Gifu University School of Medicine, Yanagido1-1, Gifu 501-1193, Japan.
authors.forename: Sayumi
authors.initials: S
authors.lastname: Matsushita
authors.affiliation: United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Yanagido1-1, Gifu 501-1193, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Nishikawa
authors.affiliation: United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Yanagido1-1, Gifu 501-1193, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Sato
authors.affiliation: United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Yanagido1-1, Gifu 501-1193, Japan; Department of Functional Bioscience, Gifu University School of Medicine, Yanagido1-1, Gifu 501-1193, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Muto
authors.affiliation: Kazusa DNA Research Institute, Kisarazu 293-0818, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nagase
authors.affiliation: United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Yanagido1-1, Gifu 501-1193, Japan; Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido1-1, Gifu 501-1193, Japan. Electronic address: hueda@gifu-u.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueda
mesh_terms: D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008954:Models, Biological; D011485:Protein Binding; D027602:Serum Response Element / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D020662:Guanine Nucleotide Exchange Factors; C527535:PLEKHG2 protein, human; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D019205:GTP-Binding Protein alpha Subunits, Gs
keywords: Gene transcription; Gαs/olf; Interaction; RhoGEF