Chemokine Receptor Dimerization and Chemotaxis
A broad array of biological responses ranging from cell polarization, movement, immune and inflammatory responses, as well as prevention of HIV-1 infection, are triggered by the chemokines, a family of structurally related chemoattractant proteins that bind to specific seven-transmembrane receptors linked to G proteins. Although it was initially believed that chemokine receptors act as monomeric entities, it has now been shown that they function as oligomers. Chemokine receptor homo– and heterodimers are found on the cell membrane; binding to their ligands stabilizes specific receptor conformations and activates distinct signaling cascades. Thorough analysis of the conformations adopted by the receptors at the membrane is therefore a prerequisite for understanding the function of these inflammatory mediators.
For study of the chemokine receptor conformations at the cell surface, we focus here on conventional biochemical and genetic methods, as well as on new imaging techniques such as those based on resonance energy transfer; we also evaluate in vitro and in vivo methods to determine certain chemokine receptor functions.
Key words:Chemokine Chemokine receptor GPCR Dimerization BRET FRET Chemotaxis
We thank the members of the DIO chemokine group, who contributed to some of the work described in this review. We also thank C. Bastos and C. Mark for secretarial support and helpful editorial assistance, respectively. This work was partially funded by grants from the EU (LSHB-CT-2005-518167 and LSHG–CT-2003-503259), the Spanish Ministry of Science and Innovation (SAF2005-03388), and the Madrid Regional Government. The Department of Immunology and Oncology was founded and is supported by the Spanish National Research Council (CSIC) and by Pfizer.
- 4.Belpario, J., Keane, M., Arenberg, D., Addison, C., Ehlert, J., Burdick, M., et al. (2000) CXC chemokines in angiogenesis. J. Leuk. Biol. 68, 1–8.Google Scholar
- 13.Ganju, R. K., Brubaker, S. A., Meyer, J., Dutt, P., Yang, Y., Qin, S., et al. (1998) The alpha-chemokine, stromal cell-derived factor-1alpha, binds to the transmembrane G-protein-coupled CXCR-4 receptor and activates multiple signal transduction pathways. J. Biol. Chem. 273, 23169–23175.PubMedCrossRefGoogle Scholar
- 14.Knall, C., Worthen, G. S., and Johnson, G. L. (1997) Interleukin 8-stimulated phosphatidylinositol-3-kinase activity regulates the migration of human neutrophils independent of extracellular signal-regulated kinase and p38 mitogen-activated protein kinases. Proc. Natl. Acad. Sci. USA 94, 3052–3057.PubMedCrossRefGoogle Scholar
- 16.Arai, H., Tsou, C. L., and Charo, I. F. (1997) Chemotaxis in a lymphocyte cell line transfected with C-C chemokine receptor 2B: evidence that directed migration is mediated by βγ dimers released by activation of Gαi-coupled receptors. Proc. Natl. Acad. Sci. USA 94, 14495–14499.PubMedCrossRefGoogle Scholar
- 17.L’Heureux, G. P., Bourgoin, S., Jean, N., McColl, S. R., and Naccache, P. H. (1995) Diverging signal transduction pathways activated by interleukin-8 and related chemokines in human neutrophils: interleukin-8, but not NAP-2 or GRO alpha, stimulates phospholipase D activity. Blood 85, 522–531.PubMedGoogle Scholar
- 26.Rodriguez-Frade, J. M., Vila-Coro, A. J., de Ana, A. M., Albar, J. P., Martinez, A. C., and Mellado, M. (1999) The chemokine monocyte chemoattractant protein-1 induces functional responses through dimerization of its receptor CCR2. Proc. Natl. Acad. Sci. USA 96, 3628–3633.PubMedCrossRefGoogle Scholar
- 35.Periasami, A., Elangovan, M., Elliot, E., and Brautigan, D. L. (2002) Fluorescence lifetime imaging (FLIM) of green fluorescent fusion proteins in living cells. Methods Mol. Biol. 183, 189–200.Google Scholar