Gαi2 and Gαi3 Differentially Regulate Arrest from Flow and Chemotaxis in Mouse Neutrophils

Abstract

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 Gαi2 and Gαi3-containing heterotrimeric G proteins. Neutrophils arrest in response to CXCR2 stimulation. This is defective in Gαi2 deficient neutrophils. Here, we show that Gαi3 deficient neutrophils showed reduced transmigration but normal arrest in mice. We also tested Gαi2 or Gαi3 deficient neutrophils in a CXCL1 gradient generated by a microfluidic device. Gαi3, but not Gαi2, deficient neutrophils showed significantly reduced migration and directionality. This was confirmed in a model of sterile inflammation in vivo. Gαi2, but not Gαi3, deficient neutrophils showed decreased Ca2+ flux in response to CXCR2 stimulation. Conversely, Gαi3, but not Gαi2, deficient neutrophils exhibited reduced AKT phosphorylation upon CXCR2 stimulation. We conclude that Gαi2 controls arrest and Gαi3 controls transmigration and chemotaxis in response to chemokine stimulation of neutrophils.

Chemokine-triggered microtubule polymerization promotes neutrophil chemotaxis and invasion but not transendothelial migration

“…Once extravasating, neutrophils interact with inflamed pericytes via two key components, namely, the CXCR2 ligand CXCL1 and the β2 integrin ligand ICAM‐1 . We therefore next tested if taxol inhibition of neutrophils interferes with chemokinetic neutrophil motility on a substrate coated with CXCL1 alone.…”

“…Experiment in C is a representative of 5. ns = nonsignificant integrin ligand ICAM-1. [36][37][38][39][40] We therefore next tested if taxol inhibition of neutrophils interferes with chemokinetic neutrophil motility on a substrate coated with CXCL1 alone. This locomotion was confirmed to be both CXCL1 and CXCR2 dependent (Supplemental Fig.…”

Autoregulatory circuit regulating basolateral cargo export from the TGN: role of the orphan receptor GPRC5A in PKD signaling and cell polarity

“…Moreover, recently, it has has been shown to be activated by a non-GPCR dependent mechanism at the Golgi (Lo et al, 2015). Gαi3 is also activated on other subcellular membranes, like LC3-positive autophagosomes (Garcia-Marcos et al, 2011), melanosomes (Young et al, 2011) and at the plasma membrane (Thompson et al, 2007;Kuwano et al, 2016). Thus, the same signaling molecules can operate in different ways in different regulatory networks for different purposes.…”

Exercise Inhibits the Effects of Smoke‐Induced COPD Involving Modulation of STAT3

“…Of note, the reduction of the proinflammatory molecule CXCL1, a potent chemoattractant of neutrophils [ 28 – 30 ], in BAL and in the serum of COPD+Exe group could putatively lead to the reduction of neutrophil migration and activation in airways and consequently minimize the damage of chronic exposition of cigarette smoke in the lung. Moreover, it was demonstrated that polymorphonuclear cell migration after a session of physical exercise is altered due to lack of response of cell-specific membrane receptors to specific chemokines, as well as to the alteration in the polarization of these cells [ 31 ].…”