Ligand-induced partitioning of human CXCR1 chemokine receptors with lipid raft microenvironments facilitates G-protein-dependent signaling.
Ligand binding to a chemokine receptor triggers signaling events through heterotrimeric G-proteins. The mechanisms underlying receptor-mediated G-protein activation in the heterogeneous microenvironments of the plasma membrane are unclear. Here, using live-cell fluorescence resonance energy transfer imaging to detect the proximity between CXCR1-cyan fluorescent protein (CFP) and fluorescence probes that label lipid raft or non-lipid raft microdomains and using fluorescence recovery after photobleaching analysis to measure the lateral diffusion of CXCR1-CFP, we found that interleukin-8 induces association between the receptors and lipid raft microenvironments. Disruption of lipid rafts impaired G-protein-dependent signaling, such as Ca2+ responses and phosphatidylinositol 3-kinase activation, but had no effect on ligand-binding function and did not completely abolish ligand-induced receptor phosphorylation. Our results suggest a novel mechanism by which ligand binding to CXCR1 promotes lipid raft partitioning of receptors and facilitates activation of heterotrimeric G-proteins.
Jiao
Xuanmao
X
Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, NIH, 12441 Parklawn Drive, Twinbrook II, Rockville, Maryland 20852, USA.
Zhang
Ning
N
Xu
Xuehua
X
Oppenheim
Joost J
JJ
Jin
Tian
T
D015153:Blotting, Western; D002460:Cell Line; D036681:Fluorescence Recovery After Photobleaching; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016209:Interleukin-8 / Q000032:analysis / Q000378:metabolism; D008024:Ligands; D021962:Membrane Microdomains / Q000378:metabolism*; D008954:Models, Biological; D010766:Phosphorylation; D023062:Receptors, Interleukin-8A / Q000378:metabolism*; D015398:Signal Transduction
C485182:Cyan Fluorescent Protein; D005456:Fluorescent Dyes; D016209:Interleukin-8; D008024:Ligands; D023062:Receptors, Interleukin-8A; D049452:Green Fluorescent Proteins; D020962:Heterotrimeric GTP-Binding Proteins