CONCLUSIONS GENERALES ET PERSPECTIVES PERSPECTIVES

Au cours de ce travail, nous avons cherché à compléter nos connaissances quant aux fonctions cellulaires de CXCR4, en recherchant ou caractérisant les interactions que ce récepteur est susceptible d'avoir avec des récepteurs aux chimiokines appartenant à une autre famille, à savoir CCR2 et CCR5.

Cette étude des mécanismes de dimérisation s'est révélée fructueuse. Il était connu que CXCR4 était capable de former des homodimères, et des hétérodimères avec CCR2 mais pas avec CCR5. Nous avons cependant montré par une technique de transfer d’énergie (BRET) que CCR5 et CCR2 forment des hétérodimères avec CXCR4 avec autant d'efficacité que des homodimères. Nous avons observé une coopérativité négative en termes de liaison de ligand, lorsque les deux récepteurs d'un hétérodimère sont coexprimés. Cette observation démontre qu'un dimère de récepteur ne peut lier qu'une seule chimiokine avec haute affinité. De plus, des molécules antagonistes sont capables de transmoduler de manière allostérique la liaison et la réponse fonctionnelle de chimiokines se liant sur l’autre partenaire du dimère, que ce soit en terme de mobilisation de calcium dans un système hétérologue ou en terme de chimiotactisme ex vivo ou in vivo. Ces résultats, tout à fait neufs et originaux, soulignent l’importance fonctionnelle des interactions entre récepteurs aux chimiokines, mais sans doute aussi entre les GPCRs en général, avec des conséquences sur le développement et l’utilisation de nouvelles molécules à usage thérapeutique. Cette notion de dimérisation est importante pour l'interprétation de la pharmacologie de récepteurs dans leur environnement naturel, et est susceptible de développements important permettant d'appréhender mieux la structure des dimères, la dynamique de leur association, et les mécanismes d'activation des récepteurs en général au sein de leurs structures dimériques.

Ce travail ouvre dès lors de nombreuses perspectives. Alors que la majorité des études concernant des effets thérapeutiques sont réalisées au sein de cellules recombinantes n’exprimant qu’un récepteur, notre étude suggère que ce système n’est pas idéal et démontre que de la co-expression de récepteurs peut découler des effets non attendus, une molécule

antagoniste pouvant avoir des effets sur un récepteur auquel il ne se lie pas. Il serait également intéressant d’étudier les conséquences de la dimérisation de CXCR4 et CCR5 sur la liaison de gp120, glycoprotéine virale permettant l’entrée du VIH dans les cellules, et de déterminer si de petites molécules antagonistes pourraient inhiber la liaison de celle-ci aux deux récepteurs majeurs de l’infection par le VIH.

8. Bibliographie

Reference List

AbdAlla S, Zaki E, Lother H and Quitterer U (1999) Involvement of the Amino Terminus of the B(2) Receptor in Agonist-Induced Receptor Dimerization. J Biol Chem 274: pp 26079-26084.

Agnati LF, Fuxe K, Zoli M, Rondanini C and Ogren S O (1982) New Vistas on Synaptic Plasticity: the Receptor Mosaic Hypothesis of the Engram. Med Biol 60: pp 183-190. Ai LS and Liao F (2002) Mutating the Four Extracellular Cysteines in the Chemokine Receptor CCR6 Reveals Their Differing Roles in Receptor Trafficking, Ligand Binding, and Signaling. Biochemistry 41: pp 8332-8341.

Aiuti A, Webb I J, Bleul C, Springer T and Gutierrez-Ramos J C (1997) The Chemokine SDF-1 Is a Chemoattractant for Human CD34+ Hematopoietic Progenitor Cells and Provides a New Mechanism to Explain the Mobilization of CD34+ Progenitors to Peripheral Blood. J Exp Med 185: pp 111-120.

Albizu L, Balestre M N, Breton C, Pin J P, Manning M, Mouillac B, Barberis C and Durroux T (2006) Probing the Existence of G Protein-Coupled Receptor Dimers by Positive and Negative Ligand-Dependent Cooperative Binding. Mol Pharmacol 70: pp 1783-1791. Ali S, Palmer A C, Banerjee B, Fritchley S J and Kirby J A (2000) Examination of the

Function of RANTES, MIP-1alpha, and MIP-1beta Following Interaction With Heparin-Like Glycosaminoglycans. J Biol Chem 275: pp 11721-11727.

Alkhatib G, Combadiere C, Broder C C, Feng Y, Kennedy P E, Murphy P M and Berger E A (1996) CC CKR5: a RANTES, MIP-1alpha, MIP-1beta Receptor As a Fusion Cofactor for Macrophage-Tropic HIV-1. Science 272: pp 1955-1958.

Altenbach C, Klein-Seetharaman J, Cai K, Khorana H G and Hubbell W L (2001) Structure and Function in Rhodopsin: Mapping Light-Dependent Changes in Distance Between Residue 316 in Helix 8 and Residues in the Sequence 60-75, Covering the Cytoplasmic End of Helices

TM1 and TM2 and Their Connection Loop CL1. Biochemistry 40: pp 15493-15500.

Arenzana-Seisdedos F, Virelizier J L, Rousset D, Clark-Lewis I, Loetscher P, Moser B and Baggiolini M (1996) HIV Blocked by Chemokine Antagonist. Nature 383: pp 400.

Ayoub MA, Couturier C, Lucas-Meunier E, Angers S, Fossier P, Bouvier M and Jockers R (2002) Monitoring of Ligand-Independent Dimerization and Ligand-Induced Conformational Changes of Melatonin Receptors in Living Cells by Bioluminescence Resonance Energy Transfer. J Biol Chem 277: pp 21522-21528.

Ayoub MA, Levoye A, Delagrange P and Jockers R (2004) Preferential Formation of MT1/MT2 Melatonin Receptor Heterodimers With Distinct Ligand Interaction Properties

Baba M, Nishimura O, Kanzaki N, Okamoto M, Sawada H, Iizawa Y, Shiraishi M, Aramaki Y, Okonogi K, Ogawa Y, Meguro K and Fujino M (1999) A Small-Molecule, Nonpeptide CCR5 Antagonist With Highly Potent and Selective Anti-HIV-1 Activity. Proc Natl Acad Sci U S A 96: pp 5698-5703.

Babcock GJ, Farzan M and Sodroski J (2003) Ligand-Independent Dimerization of CXCR4, a Principal HIV-1 Coreceptor. Journal of Biological Chemistry 278: pp 3378-3385.

Baggiolini M (1998) Chemokines and Leukocyte Traffic. Nature 392: pp 565-568.

Bagri A, Gurney T, He X, Zou Y R, Littman D R, Tessier-Lavigne M and Pleasure S J (2002) The Chemokine SDF1 Regulates Migration of Dentate Granule Cells. Development 129: pp 4249-4260.

Balabanian K, Lagane B, Infantino S, Chow K Y, Harriague J, Moepps B, Arenzana-Seisdedos F, Thelen M and Bachelerie F (2005) The Chemokine SDF-1/CXCL12 Binds to and Signals Through the Orphan Receptor RDC1 in T Lymphocytes. J Biol Chem 280: pp 35760-35766.

Baldwin ET, Weber I T, St Charles R, Xuan J C, Appella E, Yamada M, Matsushima K, Edwards B F, Clore G M, Gronenborn A M and . (1991) Crystal Structure of Interleukin 8: Symbiosis of NMR and Crystallography. Proc Natl Acad Sci U S A 88: pp 502-506.

Bargmann CI (1997) Olfactory Receptors, Vomeronasal Receptors, and the Organization of Olfactory Information. Cell 90: pp 585-587.

Barki-Harrington L, Luttrell L M and Rockman H A (2003) Dual Inhibition of Beta-Adrenergic and Angiotensin II Receptors by a Single Antagonist: a Functional Role for Receptor-Receptor Interaction in Vivo. Circulation 108: pp 1611-1618.

Benkirane M, Jin D Y, Chun R F, Koup R A and Jeang K T (1997) Mechanism of

Transdominant Inhibition of CCR5-Mediated HIV-1 Infection by Ccr5delta32. J Biol Chem 272: pp 30603-30606.

Berger EA, Murphy P M and Farber J M (1999) Chemokine Receptors As HIV-1

Coreceptors: Roles in Viral Entry, Tropism, and Disease. Annual Review of Immunology 17: pp 657-700.

Berglund MM, Schober D A, Esterman M A and Gehlert D R (2003) Neuropeptide Y Y4 Receptor Homodimers Dissociate Upon Agonist Stimulation. J Pharmacol Exp Ther 307: pp 1120-1126.

Bernhagen J, Krohn R, Lue H, Gregory J L, Zernecke A, Koenen R R, Dewor M, Georgiev I, Schober A, Leng L, Kooistra T, Fingerle-Rowson G, Ghezzi P, Kleemann R, McColl S R, Bucala R, Hickey M J and Weber C (2007) MIF Is a Noncognate Ligand of CXC Chemokine Receptors in Inflammatory and Atherogenic Cell Recruitment. Nat Med 13: pp 587-596. Berstein G, Blank J L, Smrcka A V, Higashijima T, Sternweis P C, Exton J H and Ross E M (1992) Reconstitution of Agonist-Stimulated Phosphatidylinositol 4,5-Bisphosphate

Hydrolysis Using Purified M1 Muscarinic Receptor, Gq/11, and Phospholipase C-Beta 1. J Biol Chem 267: pp 8081-8088.

Berthouze M, Ayoub M, Russo O, Rivail L, Sicsic S, Fischmeister R, Berque-Bestel I, Jockers R and Lezoualc'h F (2005) Constitutive Dimerization of Human Serotonin 5-HT4 Receptors in Living Cells. FEBS Lett 579: pp 2973-2980.

Berthouze M, Rivail L, Lucas A, Ayoub M A, Russo O, Sicsic S, Fischmeister R, Berque-Bestel I, Jockers R and Lezoualc'h F (2007) Two Transmembrane Cys Residues Are Involved in 5-HT4 Receptor Dimerization. Biochem Biophys Res Commun 356: pp 642-647.

Binet V, Brajon C, Le Corre L, Acher F, Pin J P and Prezeau L (2004) The Heptahelical Domain of GABA(B2) Is Activated Directly by CGP7930, a Positive Allosteric Modulator of the GABA(B) Receptor. J Biol Chem 279: pp 29085-29091.

Blanpain C, Buser R, Power C A, Edgerton M, Buchanan C, Mack M, Simmons G, Clapham P R, Parmentier M and Proudfoot A E (2001) A Chimeric MIP-1alpha/RANTES Protein Demonstrates the Use of Different Regions of the RANTES Protein to Bind and Activate Its Receptors. J Leukoc Biol 69: pp 977-985.

Blanpain C, Doranz B J, Bondue A, Govaerts C, De Leener A, Vassart G, Doms R W, Proudfoot A and Parmentier M (2003) The Core Domain of Chemokines Binds CCR5 Extracellular Domains While Their Amino Terminus Interacts With the Transmembrane Helix Bundle. J Biol Chem 278: pp 5179-5187.

Blanpain C, Doranz B J, Vakili J, Rucker J, Govaerts C, Baik S S, Lorthioir O, Migeotte I, Libert F, Baleux F, Vassart G, Doms R W and Parmentier M (1999a) Multiple Charged and Aromatic Residues in CCR5 Amino-Terminal Domain Are Involved in High Affinity Binding of Both Chemokines and HIV-1 Env Protein. J Biol Chem 274: pp 34719-34727.

Blanpain C, Lee B, Vakili J, Doranz B J, Govaerts C, Migeotte I, Sharron M, Dupriez V, Vassart G, Doms R W and Parmentier M (1999b) Extracellular Cysteines of CCR5 Are Required for Chemokine Binding, but Dispensable for HIV-1 Coreceptor Activity. J Biol

Chem 274: pp 18902-18908.

Blanpain C, Migeotte I, Lee B, Vakili J, Doranz B J, Govaerts C, Vassart G, Doms R W and Parmentier M (1999c) CCR5 Binds Multiple CC-Chemokines: MCP-3 Acts As a Natural Antagonist. Blood 94: pp 1899-1905.

Bleul CC, Farzan M, Choe H, Parolin C, Clark-Lewis I, Sodroski J and Springer T A (1996) The Lymphocyte Chemoattractant SDF-1 Is a Ligand for LESTR/Fusin and Blocks HIV-1 Entry. Nature 382: pp 829-833.

Bockaert J and Pin J P (1999) Molecular Tinkering of G Protein-Coupled Receptors: an Evolutionary Success. Embo Journal 18: pp 1723-1729.

Bondue A, Jao S C, Blanpain C, Parmentier M and LiWang P J (2002) Characterization of the Role of the N-Loop of MIP-1 Beta in CCR5 Binding. Biochemistry 41: pp 13548-13555. Boring L, Gosling J, Cleary M and Charo I F (1998) Decreased Lesion Formation in CCR2-/- Mice Reveals a Role for Chemokines in the Initiation of Atherosclerosis. Nature 394: pp 894-897.

Bouvier M (2001) Oligomerization of G-Protein-Coupled Transmitter Receptors. Nat Rev Neurosci 2: pp 274-286.

Breitwieser GE (2004) G Protein-Coupled Receptor Oligomerization - Implications for G Protein Activation and Cell Signaling. Circulation Research 94: pp 17-27.

Brown EM, Gamba G, Riccardi D, Lombardi M, Butters R, Kifor O, Sun A, Hediger M A, Lytton J and Hebert S C (1993) Cloning and Characterization of an Extracellular Ca(2+)-Sensing Receptor From Bovine Parathyroid. Nature 366: pp 575-580.

Broxmeyer HE, Cooper S, Kohli L, Hangoc G, Lee Y, Mantel C, Clapp D W and Kim C H (2003) Transgenic Expression of Stromal Cell-Derived Factor-1/CXC Chemokine Ligand 12 Enhances Myeloid Progenitor Cell Survival/Antiapoptosis in Vitro in Response to Growth Factor Withdrawal and Enhances Myelopoiesis in Vivo. J Immunol 170: pp 421-429. Campbell JJ, Hedrick J, Zlotnik A, Siani M A, Thompson D A and Butcher E C (1998) Chemokines and the Arrest of Lymphocytes Rolling Under Flow Conditions. Science 279: pp 381-384.

Canals M, Marcellino D, Fanelli F, Ciruela F, de Benedetti P, Goldberg S R, Neve K, Fuxe K, Agnati L F, Woods A S, Ferre S, Lluis C, Bouvier M and Franco R (2003) Adenosine A2A-Dopamine D2 Receptor-Receptor Heteromerization: Qualitative and Quantitative Assessment by Fluorescence and Bioluminescence Energy Transfer. J Biol Chem 278: pp 46741-46749. Carrillo JJ, Pediani J and Milligan G (2003) Dimers of Class A G Protein-Coupled Receptors Function Via Agonist-Mediated Trans-Activation of Associated G Proteins. Journal of Biological Chemistry 278: pp 42578-42587.

Carrillo JJ, Stevens P A and Milligan G (2002) Measurement of AgonistDependent and -Independent Signal Initiation of Alpha(1b)-Adrenoceptor Mutants by Direct Analysis of Guanine Nucleotide Exchange on the G Protein Galpha(11). J Pharmacol Exp Ther 302: pp 1080-1088.

Charo IF and Taubman M B (2004) Chemokines in the Pathogenesis of Vascular Disease. Circ Res 95: pp 858-866.

Cheng ZJ and Miller L J (2001) Agonist-Dependent Dissociation of Oligomeric Complexes of G Protein-Coupled Cholecystokinin Receptors Demonstrated in Living Cells Using

Bioluminescence Resonance Energy Transfer. J Biol Chem 276: pp 48040-48047. Christopoulos A and Kenakin T (2002) G Protein-Coupled Receptor Allosterism and Complexing. Pharmacol Rev 54: pp 323-374.

Chung CW, Cooke R M, Proudfoot A E and Wells T N (1995) The Three-Dimensional Solution Structure of RANTES. Biochemistry 34: pp 9307-9314.

Clark-Lewis I, Mattioli I, Gong J H and Loetscher P (2003) Structure-Function Relationship

Between the Human Chemokine Receptor CXCR3 and Its Ligands. J Biol Chem 278: pp

289-295.

Clemetson KJ, Clemetson J M, Proudfoot A E, Power C A, Baggiolini M and Wells T N (2000) Functional Expression of CCR1, CCR3, CCR4, and CXCR4 Chemokine Receptors on Human Platelets. Blood 96: pp 4046-4054.

Clore GM, Appella E, Yamada M, Matsushima K and Gronenborn A M (1990) Three-Dimensional Structure of Interleukin 8 in Solution. Biochemistry 29: pp 1689-1696.

Clore GM and Gronenborn A M (1995) 3-Dimensional Structures of Alpha-Chemokines and Beta-Chemokines. Faseb Journal 9: pp 57-62.

Crump MP, Gong J H, Loetscher P, Rajarathnam K, Amara A, Arenzana-Seisdedos F, Virelizier J L, Baggiolini M, Sykes B D and Clark-Lewis I (1997) Solution Structure and Basis for Functional Activity of Stromal Cell-Derived Factor-1; Dissociation of CXCR4 Activation From Binding and Inhibition of HIV-1. EMBO J 16: pp 6996-7007.

Cvejic S and Devi L A (1997) Dimerization of the Delta Opioid Receptor: Implication for a Role in Receptor Internalization. Journal of Biological Chemistry 272: pp 26959-26964. Daniels GD, Zou J, Charlemagne J, Partula S, Cunningham C and Secombes C J (1999) Cloning of Two Chemokine Receptor Homologs (CXC-R4 and CC-R7) in Rainbow Trout Oncorhynchus Mykiss. J Leukoc Biol 65: pp 684-690.

Davis ME, Akera T, Brody T M and Watson L (1977) Opiate Receptor: Cooperativity of Binding Observed in Brain Slices. Proc Natl Acad Sci U S A 74: pp 5764-5766.

De Clercq E, Yamamoto N, Pauwels R, Balzarini J, Witvrouw M, De Vreese K, Debyser Z, Rosenwirth B, Peichl P, Datema R and . (1994) Highly Potent and Selective Inhibition of

Human Immunodeficiency Virus by the Bicyclam Derivative JM3100. Antimicrob Agents

Chemother 38: pp 668-674.

De Lean A, Stadel J M and Lefkowitz R J (1980) A Ternary Complex Model Explains the Agonist-Specific Binding Properties of the Adenylate Cyclase-Coupled Beta-Adrenergic Receptor. J Biol Chem 255: pp 7108-7117.

de Meyts P (1976) Cooperative Properties of Hormone Receptors in Cell Membranes. J Supramol Struct 4: pp 241-258.

de Meyts P, Roth J, Neville D M, Jr., Gavin J R, III and Lesniak M A (1973) Insulin

Interactions With Its Receptors: Experimental Evidence for Negative Cooperativity. Biochem Biophys Res Commun 55: pp 154-161.

Dean M, Carrington M, Winkler C, Huttley G A, Smith M W, Allikmets R, Goedert J J, Buchbinder S P, Vittinghoff E, Gomperts E, Donfield S, Vlahov D, Kaslow R, Saah A, Rinaldo C, Detels R and O'Brien S J (1996) Genetic Restriction of HIV-1 Infection and Progression to AIDS by a Deletion Allele of the CKR5 Structural Gene. Hemophilia Growth and Development Study, Multicenter AIDS Cohort Study, Multicenter Hemophilia Cohort Study, San Francisco City Cohort, ALIVE Study. Science 273: pp 1856-1862.

Dean MK, Higgs C, Smith R E, Bywater R P, Snell C R, Scott P D, Upton G J G, Howe T J and Reynolds C A (2001) Dimerization of G-Protein-Coupled Receptors. Journal of

Medicinal Chemistry 44: pp 4595-4614.

Deng H, Liu R, Ellmeier W, Choe S, Unutmaz D, Burkhart M, Di Marzio P, Marmon S, Sutton R E, Hill C M, Davis C B, Peiper S C, Schall T J, Littman D R and Landau N R (1996) Identification of a Major Co-Receptor for Primary Isolates of HIV-1. Nature 381: pp 661-666.

Detheux M, Standker L, Vakili J, Munch J, Forssmann U, Adermann K, Pohlmann S, Vassart G, Kirchhoff F, Parmentier M and Forssmann W G (2000) Natural Proteolytic Processing of Hemofiltrate CC Chemokine 1 Generates a Potent CC Chemokine Receptor (CCR)1 and CCR5 Agonist With Anti-HIV Properties. Journal of Experimental Medicine 192: pp 1501-1508.

Dinger MC, Bader J E, Kobor A D, Kretzschmar A K and Beck-Sickinger A G (2003) Homodimerization of Neuropeptide y Receptors Investigated by Fluorescence Resonance Energy Transfer in Living Cells. J Biol Chem 278: pp 10562-10571.

Donzella GA, Schols D, Lin S W, Este J A, Nagashima K A, Maddon P J, Allaway G P, Sakmar T P, Henson G, De Clercq E and Moore J P (1998) AMD3100, a Small Molecule Inhibitor of HIV-1 Entry Via the CXCR4 Co-Receptor. Nat Med 4: pp 72-77.

Doranz BJ, Rucker J, Yi Y, Smyth R J, Samson M, Peiper S C, Parmentier M, Collman R G and Doms R W (1996) A Dual-Tropic Primary HIV-1 Isolate That Uses Fusin and the

Beta-Chemokine Receptors CKR-5, CKR-3, and CKR-2b As Fusion Cofactors. Cell 85: pp

1149-1158.

El Asmar L, Springael J Y, Ballet S, Andrieu E U, Vassart G and Parmentier M (2005)

Evidence for Negative Binding Cooperativity Within CCR5-CCR2b Heterodimers. Mol

Pharmacol 67: pp 460-469.

Elisseeva EL, Slupsky C M, Crump M P, Clark-Lewis I and Sykes B D (2000) NMR Studies of Active N-Terminal Peptides of Stromal Cell-Derived Factor-1. Structural Basis for

Receptor Binding. J Biol Chem 275: pp 26799-26805.

Farrens DL, Altenbach C, Yang K, Hubbell W L and Khorana H G (1996) Requirement of Rigid-Body Motion of Transmembrane Helices for Light Activation of Rhodopsin. Science 274: pp 768-770.

Farzan M, Mirzabekov T, Kolchinsky P, Wyatt R, Cayabyab M, Gerard N P, Gerard C, Sodroski J and Choe H (1999) Tyrosine Sulfation of the Amino Terminus of CCR5 Facilitates HIV-1 Entry. Cell 96: pp 667-676.

Feng Y, Broder C C, Kennedy P E and Berger E A (1996) HIV-1 Entry Cofactor: Functional

CDNA Cloning of a Seven-Transmembrane, G Protein-Coupled Receptor. Science 272: pp

872-877.

Ferre S, Karcz-Kubicha M, Hope B T, Popoli P, Burgueno J, Gutierrez M A, Casado V, Fuxe K, Goldberg S R, Lluis C, Franco R and Ciruela F (2002) Synergistic Interaction Between Adenosine A2A and Glutamate MGlu5 Receptors: Implications for Striatal Neuronal Function. Proc Natl Acad Sci U S A 99: pp 11940-11945.

Fong AM, Alam S M, Imai T, Haribabu B and Patel D D (2002) CX3CR1 Tyrosine Sulfation Enhances Fractalkine-Induced Cell Adhesion. J Biol Chem 277: pp 19418-19423.

Fotiadis D, Liang Y, Filipek S, Saperstein D A, Engel A and Palczewski K (2003) Atomic-Force Microscopy: Rhodopsin Dimers in Native Disc Membranes. Nature 421: pp 127-128.

Frade JMR, Llorente M, Mellado M, Alcami J, GutierrezRamos J C, Zaballos A, delReal G and MartinezA C (1997) The Amino-Terminal Domain of the CCR2 Chemokine Receptor Acts As Coreceptor for HIV-1 Infection. Journal of Clinical Investigation 100: pp 497-502. Fricker SP, Anastassov V, Cox J, Darkes M C, Grujic O, Idzan S R, Labrecque J, Lau G, Mosi R M, Nelson K L, Qin L, Santucci Z and Wong R S (2006) Characterization of the Molecular Pharmacology of AMD3100: a Specific Antagonist of the G-Protein Coupled

Chemokine Receptor, CXCR4. Biochem Pharmacol 72: pp 588-596.

Galvez T, Duthey B, Kniazeff J, Blahos J, Rovelli G, Bettler B, Prezeau L and Pin J P (2001) Allosteric Interactions Between GB1 and GB2 Subunits Are Required for Optimal GABA(B) Receptor Function. Embo Journal 20: pp 2152-2159.

Gao P, Zhou X Y, Yashiro-Ohtani Y, Yang Y F, Sugimoto N, Ono S, Nakanishi T, Obika S, Imanishi T, Egawa T, Nagasawa T, Fujiwara H and Hamaoka T (2003) The Unique Target Specificity of a Nonpeptide Chemokine Receptor Antagonist: Selective Blockade of Two Th1

Chemokine Receptors CCR5 and CXCR3. J Leukoc Biol 73: pp 273-280.

Garzino-Demo A, DeVico A L, Conant K E and Gallo R C (2000) The Role of Chemokines in Human Immunodeficiency Virus Infection. Immunol Rev 177: pp 79-87.

Gazi L, Lopez-Gimenez J F, Rudiger M P and Strange P G (2003) Constitutive

Oligomerization of Human D2 Dopamine Receptors Expressed in Spodoptera Frugiperda 9 (Sf9) and in HEK293 Cells. Analysis Using Co-Immunoprecipitation and Time-Resolved Fluorescence Resonance Energy Transfer. Eur J Biochem 270: pp 3928-3938.

Gerard C and Rollins B J (2001) Chemokines and Disease. Nature Immunology 2: pp 108-115.

Gether U (2000) Uncovering Molecular Mechanisms Involved in Activation of G Protein-Coupled Receptors. Endocr Rev 21: pp 90-113.

Gomes I, Gupta A, Filipovska J, Szeto H H, Pintar J E and Devi L A (2004) A Role for Heterodimerization of Mu and Delta Opiate Receptors in Enhancing Morphine Analgesia. Proceedings of the National Academy of Sciences of the United States of America 101: pp 5135-5139.

Gong JH and Clark-Lewis I (1995) Antagonists of Monocyte Chemoattractant Protein 1 Identified by Modification of Functionally Critical NH2-Terminal Residues. J Exp Med 181: pp 631-640.

Gong JH, Uguccioni M, Dewald B, Baggiolini M and Clark-Lewis I (1996) RANTES and

MCP-3 Antagonists Bind Multiple Chemokine Receptors. J Biol Chem 271: pp 10521-10527.

Gonzalez E, Bamshad M, Sato N, Mummidi S, Dhanda R, Catano G, Cabrera S, McBride M, Cao X H, Merrill G, O'Connell P, Bowden D W, Freedman B I, Anderson S A, Walter E A, Evans J S, Stephan K T, Clark R A, Tyagi S, Ahuja S S, Dolan M J and Ahuja S K (1999) Race-Specific HIV-1 Disease-Modifying Effects Associated With CCR5 Haplotypes. Proceedings of the National Academy of Sciences of the United States of America 96: pp 12004-12009.

Gouldson PR, Snell C R, Bywater R P, Higgs C and Reynolds C A (1998) Domain Swapping in G-Protein Coupled Receptor Dimers. Protein Eng 11: pp 1181-1193.

Guo W, Shi L and Javitch J A (2003) The Fourth Transmembrane Segment Forms the

Interface of the Dopamine D2 Receptor Homodimer. Journal of Biological Chemistry 278: pp 4385-4388.

Gupta SK, Lysko P G, Pillarisetti K, Ohlstein E and Stadel J M (1998a) Chemokine Receptors in Human Endothelial Cells. Functional Expression of CXCR4 and Its Transcriptional

Regulation by Inflammatory Cytokines. J Biol Chem 273: pp 4282-4287.

Gupta SK, Pillarisetti K, Gray S L and Stadel J M (1998b) Molecular Cloning of a Novel

Chemokine Receptor-Like Gene From Early Stage Chick Embryos. Biochem Mol Biol Int 44:

pp 673-681.

Gupta SK, Pillarisetti K and Lysko P G (1999) Modulation of CXCR4 Expression and SDF-1alpha Functional Activity During Differentiation of Human Monocytes and Macrophages. J Leukoc Biol 66: pp 135-143.

Gupta SK, Pillarisetti K, Thomas R A and Aiyar N (2001) Pharmacological Evidence for Complex and Multiple Site Interaction of CXCR4 With SDF-1alpha: Implications for Development of Selective CXCR4 Antagonists. Immunol Lett 78: pp 29-34.

Guyer CA, Horstman D A, Wilson A L, Clark J D, Cragoe E J, Jr. and Limbird L E (1990) Cloning, Sequencing, and Expression of the Gene Encoding the Porcine Alpha 2-Adrenergic Receptor. Allosteric Modulation by Na+, H+, and Amiloride Analogs. J Biol Chem 265: pp 17307-17317.

Han KH, Green S R, Tangirala R K, Tanaka S and Quehenberger O (1999) Role of the First Extracellular Loop in the Functional Activation of CCR2 - The First Extracellular Loop Contains Distinct Domains Necessary for Both Agonist Binding and Transmembrane Signaling. Journal of Biological Chemistry 274: pp 32055-32062.

Handel TM and Domaille P J (1996) Heteronuclear (1H, 13C, 15N) NMR Assignments and Solution Structure of the Monocyte Chemoattractant Protein-1 (MCP-1) Dimer. Biochemistry 35: pp 6569-6584.

Hatse S, Princen K, Bridger G, De Clercq E and Schols D (2002) Chemokine Receptor Inhibition by AMD3100 Is Strictly Confined to CXCR4. FEBS Lett 527: pp 255-262.

Hay DL, Conner A C, Howitt S G, Smith D M and Poyner D R (2003) The Pharmacology of Adrenomedullin Receptors and Their Relationship to CGRP Receptors. Journal of Molecular Neuroscience 22: pp 105-113.

Hay DL, Poyner D R and Sexton P M (2006) GPCR Modulation by RAMPS. Pharmacology

& Therapeutics 109: pp 173-197.

Hebert TE, Moffett S, Morello J P, Loisel T P, Bichet D G, Barret C and Bouvier M (1996) A Peptide Derived From a Beta(2)-Adrenergic Receptor Transmembrane Domain Inhibits Both Receptor Dimerization and Activation. Journal of Biological Chemistry 271: pp 16384-16392.

Hernanz-Falcon P, Rodriguez-Frade J M, Serrano A, Juan D, del Sol A, Soriano S F, Roncal F, Gomez L, Valencia A, Martinez A and Mellado M (2004) Identification of Amino Acid Residues Crucial for Chemokine Receptor Dimerization. Nat Immunol 5: pp 216-223. Holst B, Elling C E and Schwartz T W (2002) Metal Ion-Mediated Agonism and Agonist

Enhancement in Melanocortin MC1 and MC4 Receptors. J Biol Chem 277: pp 47662-47670.

Honczarenko M, Le Y, Glodek A M, Majka M, Campbell J J, Ratajczak M Z and Silberstein L E (2002) CCR5-Binding Chemokines Modulate CXCL12 (SDF-1)-Induced Responses of Progenitor B Cells in Human Bone Marrow Through Heterologous Desensitization of the

CXCR4 Chemokine Receptor. Blood 100: pp 2321-2329.

Horuk R (2001) Chemokine Receptors. Cytokine Growth Factor Rev 12: pp 313-335.

Issafras H, Angers S, Bulenger S, Blanpain C, Parmentier M, Labbe-Jullie C, Bouvier M and Marullo S (2002) Constitutive Agonist-Independent CCR5 Oligomerization and Antibody-Mediated Clustering Occurring at Physiological Levels of Receptors. J Biol Chem %20;277: