| Title: | A point mutation that confers constitutive activity to CXCR4 reveals that T140 is an inverse agonist and that AMD3100 and ALX40-4C are weak partial agonists |
| Author(s): | Zhang WB; Navenot JM; Haribabu B; Tamamura H; Hiramatu K; Omagari A; Pei G; Manfredi JP; Fujii N; Broach JR; Peiper SC; |
| Address: | "Henry Vogt Cancer Research Institute, University of Louisville, Louisville, Kentucky 40202, USA" |
| ISSN/ISBN: | 0021-9258 (Print) 0021-9258 (Linking) |
| Abstract: | "CXCR4 is a G protein-coupled receptor for stromal-derived factor 1 (SDF-1) that plays a critical role in leukocyte trafficking, metastasis of mammary carcinoma, and human immunodeficiency virus type-1 infection. To elucidate the mechanism for CXCR4 activation, a constitutively active mutant (CAM) was derived by coupling the receptor to the pheromone response pathway in yeast. Conversion of Asn-119 to Ser or Ala, but not Asp or Lys, conferred autonomous CXCR4 signaling in yeast and mammalian cells. SDF-1 induced signaling in variants with substitution of Asn-119 to Ser, Ala, or Asp, but not Lys. These variants had similar cell surface expression and binding affinity for SDF-1. CXCR4-CAMs were constitutively phosphorylated and present in cytosolic inclusions. Analysis of antagonists revealed that exposure to AMD3100 or ALX40-4C induced G protein activation by CXCR4 wild type, which was greater in the CAM, whereas T140 decreased autonomous signaling. The affinity of AMD3100 and ALX40-4C binding to CAMs was less than to wild type, providing evidence of a conformational shift. These results illustrate the importance of transmembrane helix 3 in CXCR4 signaling. Insight into the mechanism for CXCR4 antagonists will allow for the development of a new generation of agents that lack partial agonist activity that may induce toxicities, as observed for AMD3100" |
| Keywords: | "Amino Acid Substitution Animals Anti-HIV Agents/pharmacology Benzylamines CHO Cells Cricetinae Cyclams GTP-Binding Proteins/metabolism Genes, Reporter Genetic Variation Heterocyclic Compounds/*pharmacology Humans Oligopeptides/*pharmacology Open Reading F;" |
| Notes: | "MedlineZhang, Wen-Bo Navenot, Jean-Marc Haribabu, Bodduluri Tamamura, Hirokazu Hiramatu, Kenichi Omagari, Akane Pei, Gang Manfredi, John P Fujii, Nobutaka Broach, James R Peiper, Stephen C eng R01 AI41346/AI/NIAID NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. 2002/03/30 J Biol Chem. 2002 Jul 5; 277(27):24515-21. doi: 10.1074/jbc.M200889200. Epub 2002 Mar 28" |
