Gαi2 and Gαi3 differentially regulate arrest from flow and chemotaxis in mouse neutrophils

Leukocyte recruitment to inflammation sites progresses in a multistep cascade. Chemokines regulate multiple steps of the cascade, including arrest, transmigration, and chemotaxis. The most important chemokine receptor in mouse neutrophils is CXCR2, which couples through Gai2-and Gai3-containing heterotrimeric G proteins. Neutrophils arrest in response to CXCR2 stimulation. This is defective in Gai2-deficient neutrophils. In this study, we show that Gai3-deficient neutrophils showed reduced transmigration but normal arrest in mice. We also tested Gai2-or Gai3-deficient neutrophils in a CXCL1 gradient generated by a microfluidic device. Gai3-, but not Gai2-, deficient neutrophils showed significantly reduced migration and directionality. This was confirmed in a model of sterile inflammation in vivo. Gai2-, but not Gai3-, deficient neutrophils showed decreased Ca2+ flux in response to CXCR2 stimulation. Conversely, Gai3-, but not Gai2-, deficient neutrophils exhibited reduced AKT phosphorylation upon CXCR2 stimulation. We conclude that Gai2 controls arrest and Gai3 controls transmigration and chemotaxis in response to chemokine stimulation of neutrophils.