title: Endogenous ARF6 interacts with Rac1 upon angiotensin II stimulation to regulate membrane ruffling and cell migration.
abstract: ARF6 and Rac1 are small GTPases known to regulate remodelling of the actin cytoskeleton. Here, we demonstrate that these monomeric G proteins are sequentially activated when HEK 293 cells expressing the angiotensin type 1 receptor (AT(1)R) are stimulated with angiotensin II (Ang II). After receptor activation, ARF6 and Rac1 transiently form a complex. Their association is, at least in part, direct and dependent on the nature of the nucleotide bound to both small G proteins. ARF6-GTP preferentially interacts with Rac1-GDP. AT(1)R expressing HEK293 cells ruffle, form membrane protrusions, and migrate in response to agonist treatment. ARF6, but not ARF1, depletion using small interfering RNAs recapitulates the ruffling and migratory phenotype observed after Ang II treatment. These results suggest that ARF6 depletion or Ang II treatment are functionally equivalent and point to a role for endogenous ARF6 as an inhibitor of Rac1 activity. Taken together, our findings reveal a novel function of endogenously expressed ARF6 and demonstrate that by interacting with Rac1, this small GTPase is a central regulator of the signaling pathways leading to actin remodeling.
authors.affiliation: Department of Pharmacology, School of Medicine, University of Montréal, Montréal, Canada H3C 3J7.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Cotton
authors.forename: Pierre-Luc
authors.initials: PL
authors.lastname: Boulay
authors.forename: Tanguy
authors.initials: T
authors.lastname: Houndolo
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vitale
authors.forename: Julie A
authors.initials: JA
authors.lastname: Pitcher
authors.forename: Audrey
authors.initials: A
authors.lastname: Claing
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D000804:Angiotensin II / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000032:analysis / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000502:physiology*; D002465:Cell Movement; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000032:analysis / Q000378:metabolism; D006801:Humans; D021381:Protein Transport; D034622:RNA Interference; D044140:Receptor, Angiotensin, Type 1 / Q000819:agonists*; D064067:Rho Guanine Nucleotide Exchange Factors; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000089982:ADP-Ribosylation Factor 6; D000199:Actins; D018797:Cell Cycle Proteins; D020662:Guanine Nucleotide Exchange Factors; D044140:Receptor, Angiotensin, Type 1; D064067:Rho Guanine Nucleotide Exchange Factors; D000804:Angiotensin II; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human; D020830:rac1 GTP-Binding Protein