| | Caveolin-1 affects serotonin binding and cell surface levels of human 5-HT7(a) receptorsEdited by Lukas Huber Received 18 July 2007; received in revised form 23 September 2007; accepted 28 September 2007. published online 08 October 2007. Abstract Studies using HeLa cells expressing 5-HT7 receptors showed that detergent resistant membranous lipid rafts purified by sucrose gradient centrifugation contained 5-HT7 receptors and caveolin-1. Caveolin-1 siRNA-mediated knockdown or serotonin (5-HT) treatment caused significant reductions of maximum [3H]5-HT binding to 5-HT7 receptors and total immunoreactivity of membranous 5-HT7 receptors in intact cells. Co-treatment with 5-HT, caveolin-1 siRNA and methyl-β-cyclodextrin had no additive effects on reducing maximum binding of [3H]5-HT to 5-HT7 receptors. 5-HT-mediated reduction of [3H]5-HT binding to 5-HT7 receptors was counteracted by genistein, but not by sucrose. Caveolin-1, specifically localized in cholesterol-enriched lipid rafts, appears to regulate constitutive and agonist-stimulated cell surface levels of 5-HT7 receptors via a clathrin-independent mechanism. Abbreviations: 5-HT, 5-hydroxytryptamine, serotonin, 5-MeOT, 5-metoxytryptamine, GPCR, G protein coupled receptor, Cav-1, caveolin-1, siRNA, small interfering RNA, KD, dissociation constant, MβCD, methyl-β-cyclodextrin Section of Translational Neuropharmacology, Department of Physiology and Pharmacology, Karolinska Institute, 171 77 Stockholm, Sweden  Corresponding author.
PII: S0014-5793(07)01043-5 doi:10.1016/j.febslet.2007.09.059 © 2007 Federation of European Biochemical Societies. Published by Elsevier BV. All rights reserved. | |
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ABSTRACT
