title: P-Rex1 directly activates RhoG to regulate GPCR-driven Rac signalling and actin polarity in neutrophils.
abstract: G-protein-coupled receptors (GPCRs) regulate the organisation of the actin cytoskeleton by activating the Rac subfamily of small GTPases. The guanine-nucleotide-exchange factor (GEF) P-Rex1 is engaged downstream of GPCRs and phosphoinositide 3-kinase (PI3K) in many cell types, and promotes tumorigenic signalling and metastasis in breast cancer and melanoma, respectively. Although P-Rex1-dependent functions have been attributed to its GEF activity towards Rac1, we show that P-Rex1 also acts as a GEF for the Rac-related GTPase RhoG, both in vitro and in GPCR-stimulated primary mouse neutrophils. Furthermore, loss of either P-Rex1 or RhoG caused equivalent reductions in GPCR-driven Rac activation and Rac-dependent NADPH oxidase activity, suggesting they both function upstream of Rac in this system. Loss of RhoG also impaired GPCR-driven recruitment of the Rac GEF DOCK2, and F-actin, to the leading edge of migrating neutrophils. Taken together, our results reveal a new signalling hierarchy in which P-Rex1, acting as a GEF for RhoG, regulates Rac-dependent functions indirectly through RhoG-dependent recruitment of DOCK2. These findings thus have broad implications for our understanding of GPCR signalling to Rho GTPases and the actin cytoskeleton.
authors.affiliation: Inositide laboratory, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
authors.forename: George
authors.initials: G
authors.lastname: Damoulakis
authors.affiliation: Inositide laboratory, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
authors.forename: Laure
authors.initials: L
authors.lastname: Gambardella
authors.affiliation: Lineberger Comprehensive Cancer Center and Department of Pharmacology, University of North Carolina at Chapel Hill, 450 West Drive, Chapel Hill, North Carolina, USA.
authors.forename: Kent L
authors.initials: KL
authors.lastname: Rossman
authors.affiliation: Inositide laboratory, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
authors.forename: Campbell D
authors.initials: CD
authors.lastname: Lawson
authors.affiliation: Inositide laboratory, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Anderson
authors.affiliation: Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Fukui
authors.affiliation: Inositide laboratory, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
authors.forename: Heidi C
authors.initials: HC
authors.lastname: Welch
authors.affiliation: Lineberger Comprehensive Cancer Center and Department of Pharmacology, University of North Carolina at Chapel Hill, 450 West Drive, Chapel Hill, North Carolina, USA.
authors.forename: Channing J
authors.initials: CJ
authors.lastname: Der
authors.affiliation: Inositide laboratory, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK.
authors.forename: Len R
authors.initials: LR
authors.lastname: Stephens
authors.affiliation: Inositide laboratory, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK phillip.hawkins@babraham.ac.uk.
authors.forename: Phillip T
authors.initials: PT
authors.lastname: Hawkins
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000818:Animals; D001943:Breast Neoplasms; D063646:Carcinogenesis; D002465:Cell Movement / Q000235:genetics; D016764:Cell Polarity / Q000235:genetics; D002478:Cells, Cultured; D020558:GTP Phosphohydrolases / Q000235:genetics; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D008545:Melanoma; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009362:Neoplasm Metastasis; D009504:Neutrophils / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D020741:rho GTP-Binding Proteins
chemical_list: C471356:DOCK2 protein, mouse; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; C511197:PREX1 protein, mouse; D043562:Receptors, G-Protein-Coupled; C489577:Rhog protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D020558:GTP Phosphohydrolases; D020741:rho GTP-Binding Proteins
keywords: Cell migration; Cell signalling; NADPH oxidase; Neutrophil; Rho GEF; Small GTPase