Dynamic regulation of neutrophil polarity and migration by the heterotrimeric G protein subunits G?i-GTP and G??.

ABSTRACT: Activation of the Gi family of heterotrimeric guanine nucleotide-binding proteins (G proteins) releases ?? subunits, which are the major transducers of chemotactic G protein-coupled receptor (GPCR)-dependent cell migration. The small molecule 12155 binds directly to G?? and activates G?? signaling without activating the G?i subunit in the Gi heterotrimer. We used 12155 to examine the relative roles of G?i and G?? 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 G?i and G?? with the mastoparan analog Mas7 resulted in normal migration. Furthermore, 12155-treated cells expressing a constitutively active form of G?i1 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 G?i in promoting cell polarization through a cAMP-dependent mechanism and in inhibiting adhesion through a cAMP-independent mechanism.

SUBMITTER: Surve CR 

PROVIDER: S-EPMC6364554 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature