| Dokumentenart: | Artikel | ||||
|---|---|---|---|---|---|
| Titel eines Journals oder einer Zeitschrift: | Naunyn-Schmiedeberg's Archives of Pharmacology | ||||
| Verlag: | SPRINGER | ||||
| Ort der Veröffentlichung: | NEW YORK | ||||
| Band: | 378 | ||||
| Nummer des Zeitschriftenheftes oder des Kapitels: | 3 | ||||
| Seitenbereich: | S. 261-274 | ||||
| Datum: | 2008 | ||||
| Institutionen: | Chemie und Pharmazie > Institut für Pharmazie > Lehrstuhl Pharmakologie und Toxikologie (Prof. Schlossmann, ehemals Prof. Seifert) | ||||
| Identifikationsnummer: |
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| Stichwörter / Keywords: | FORMYL PEPTIDE RECEPTOR; BINDING REGULATORY PROTEINS; CONSTITUTIVE ACTIVITY; SIGNAL-TRANSDUCTION; LIGAND-BINDING; ANTAGONISTS; EXPRESSION; BETA(2)-ADRENOCEPTOR; FACTOR-1-ALPHA; G(Q)-PROTEINS; chemokine receptor; stroma cell-derived factor-1 alpha; G(i)/G(o)-proteins; RGS-proteins; GTPase activity; Sf9 insect cells | ||||
| Dewey-Dezimal-Klassifikation: | 600 Technik, Medizin, angewandte Wissenschaften > 615 Pharmazie | ||||
| Status: | Veröffentlicht | ||||
| Begutachtet: | Ja, diese Version wurde begutachtet | ||||
| An der Universität Regensburg entstanden: | Ja | ||||
| Dokumenten-ID: | 67895 |
Web of ScienceZusammenfassung
The chemokine stromal cell-derived factor-1 alpha (SDF-1 alpha) binds to the chemokine receptor CXCR4 that couples to pertussis toxin-sensitive G-proteins of the G(i)/G(o)-family. CXCR4 plays a role in the pathogenesis of autoimmune diseases, human immunodeficiency virus infection and various tumors, fetal development as well as endothelial progenitor and T-cell recruitment. To this end, most ...
Zusammenfassung
The chemokine stromal cell-derived factor-1 alpha (SDF-1 alpha) binds to the chemokine receptor CXCR4 that couples to pertussis toxin-sensitive G-proteins of the G(i)/G(o)-family. CXCR4 plays a role in the pathogenesis of autoimmune diseases, human immunodeficiency virus infection and various tumors, fetal development as well as endothelial progenitor and T-cell recruitment. To this end, most CXCR4 studies have focused on the cellular level. The aim of this study was to establish a reconstitution system for the human CXCR4 that allows for the analysis of receptor/G-protein coupling at the membrane level. We wished to study specifically constitutive CXCR4 activity and the G-protein-specificity of CXCR4. We co-expressed N- and C-terminally epitope-tagged human CXCR4 with various G(i)/G(o)-proteins and regulator of G-protein signaling (RGS)-proteins in Sf9 insect cells. Expression of CXCR4, G-proteins, and RGS-proteins was verified by immunoblotting. CXCR4 coupled more effectively to G alpha(i1) and G alpha(i2) than to G alpha(i3) and G alpha(o) and insect cell G-proteins as assessed by SDF-1 alpha-stimulated high-affinity steady-state GTP hydrolysis. The RGS-proteins RGS4 and GAIP enhanced SDF-1 alpha-stimulated GTP hydrolysis. SDF-1 alpha stimulated [S-35]guanosine 5'-[gamma-thio]triphosphate (GTP gamma S) binding to G alpha(i2). RGS4 did not enhance GTP gamma S binding. Na+ salts of halides did not reduce basal GTPase activity. The bicyclam, 1-[[1,4,8,11-tetrazacyclotetradec-1-ylmethyl)phenyl]methyl]-1,4,8,11-tetrazacyclotetradecane (AMD3100), acted as CXCR4 antagonist but was devoid of inverse agonistic activity. Halides reduced the maximum SDF-1 alpha-stimulated GTP hydrolysis in the order of efficacy I- > Br- > Cl-. In addition, salts reduced the potency of SDF-1 alpha at activating GTP hydrolysis. From our data, we conclude the following: (1) Sf9 cells are a suitable system for expression of functionally intact human CXCR4; (2) Human CXCR4 couples effectively to G alpha(i1) and G alpha(i2); (3) There is no evidence for constitutive activity of CXCR4; (4) RGS-proteins enhance agonist-stimulated GTP hydrolysis, showing that GTP hydrolysis becomes rate-limiting in the presence of SDF-1 alpha; (5) By analogy to previous observations made for the beta(2)-adrenoceptor coupled to G(s), the inhibitory effects of halides on agonist-stimulated GTP hydrolysis may be due to increased GDP-affinity of G(i)-proteins, reducing the efficacy of CXCR4 at stimulating nucleotide exchange.
Metadaten zuletzt geändert: 19 Dez 2024 13:14
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