Absence of the G protein-coupled receptor G2A in mice promotes monocyte/endothelial interactions in aorta.
The G protein-coupled receptor G2A is highly expressed on macrophages and lymphocytes and has been localized to atherosclerotic plaques. We examined the role of G2A in modulating monocyte/endothelial interactions in the vessel wall. We measured adhesion of WEHI 78/24 monocytes to aortas of C57BL/6 (B6) and G2A-deficient (G2A(-/-)) mice using an ex vivo adhesion assay. G2A(-/-) mice had 10-fold elevations in adhesion of monocytes to aortas. Injection of GFP-expressing wild-type macrophages into B6 and G2A(-/-) mice in vivo showed increased macrophage accumulation in the aortic wall of G2A(-/-) mice. We isolated aortic endothelial cells (ECs) from B6 and G2A(-/-) mice and found a 2-fold increase in intercellular adhesion molecule-1 and E-selectin surface expression on G2A(-/-) ECs using flow cytometry. Using ELISA, we found a 3-fold increase in interleukin-6 and monocyte chemoattractant protein-1 production by G2A(-/-) ECs compared with B6 ECs. We found a dramatic increase in nuclear localization of the p65 subunit of nuclear factor kappaB in G2A(-/-) ECs. Transfection of G2A into G2A(-/-) ECs to restore normal expression levels reduced p65 nuclear localization to 35%. Restoration of G2A expression in G2A(-/-) ECs significantly reduced intercellular adhesion molecule-1 and endothelial selectin surface expression and reduced monocyte chemoattractant protein-1 and interleukin-6 production. Restoring G2A to G2A(-/-) ECs reduced monocyte adhesion by 80% compared with G2A(-/-) ECs in a flow chamber assay. Absence of G2A in endothelium results in proinflammatory signaling and increased monocyte/endothelial interactions in the aortic wall. Thus, endothelial G2A expression may aid in prevention of vascular inflammation and atherosclerosis.
Bolick
David T
DT
Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA.
Whetzel
Angela M
AM
Skaflen
Marcus
M
Deem
Tracy L
TL
Lee
Jianyi
J
Hedrick
Catherine C
CC
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000473:pathology / Q000502:physiology*; D050197:Atherosclerosis / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D002448:Cell Adhesion / Q000235:genetics; D002450:Cell Communication / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000473:pathology / Q000502:physiology*; D007249:Inflammation / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009000:Monocytes / Q000166:cytology / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled / Q000172:deficiency* / Q000235:genetics / Q000502:physiology
D018797:Cell Cycle Proteins; C115270:G2A receptor; D043562:Receptors, G-Protein-Coupled