title: Dynamic regulation of neutrophil polarity and migration by the heterotrimeric G protein subunits Gαi-GTP and Gβγ.
abstract: Activation of the Gi family of heterotrimeric guanine nucleotide-binding proteins (G proteins) releases βγ subunits, which are the major transducers of chemotactic G protein-coupled receptor (GPCR)-dependent cell migration. The small molecule 12155 binds directly to Gβγ and activates Gβγ signaling without activating the Gαi subunit in the Gi heterotrimer. We used 12155 to examine the relative roles of Gαi and Gβγ activation in the migration of neutrophils on surfaces coated with the integrin ligand intercellular adhesion molecule-1 (ICAM-1). We found that 12155 suppressed basal migration by inhibiting the polarization of neutrophils and increasing their adhesion to ICAM-1-coated surfaces. GPCR-independent activation of endogenous Gαi and Gβγ with the mastoparan analog Mas7 resulted in normal migration. Furthermore, 12155-treated cells expressing a constitutively active form of Gαi1 became polarized and migrated. The extent and duration of signaling by the second messenger cyclic adenosine monophosphate (cAMP) were enhanced by 12155. Inhibiting the activity of cAMP-dependent protein kinase (PKA) restored the polarity of 12155-treated cells but did not decrease their adhesion to ICAM-1 and failed to restore migration. Together, these data provide evidence for a direct role of activated Gαi in promoting cell polarization through a cAMP-dependent mechanism and in inhibiting adhesion through a cAMP-independent mechanism.
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester, Rochester, NY 14642, USA.
authors.forename: Chinmay R
authors.initials: CR
authors.lastname: Surve
authors.affiliation: Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA.
authors.forename: Jesi Y
authors.initials: JY
authors.lastname: To
authors.affiliation: Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA.
authors.forename: Sundeep
authors.initials: S
authors.lastname: Malik
authors.affiliation: Department of Immunology and Microbiology, University of Rochester, Rochester, NY 14642, USA.
authors.forename: Minsoo
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester, Rochester, NY 14642, USA. Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA. alan_smrcka@URMC.rochester.edu.
authors.forename: Alan V
authors.initials: AV
authors.lastname: Smrcka
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000235:genetics / Q000378:metabolism*; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics / Q000378:metabolism*; D018922:HL-60 Cells; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000737:chemistry; D036341:Intercellular Signaling Peptides and Proteins; D051379:Mice; D010455:Peptides / Q000494:pharmacology
chemical_list: D044387:GTP-Binding Protein beta Subunits; C573420:ICAM1 protein, human; C090509:Icam1 protein, mouse; D036341:Intercellular Signaling Peptides and Proteins; C084070:Mas7 protein, synthetic; D010455:Peptides; D018799:Intercellular Adhesion Molecule-1; D019206:GTP-Binding Protein alpha Subunits, Gi-Go