11805206

pubmed:Citation

2

We have examined the cellular processes underlying the desensitization of the 5-hydroxytryptamine (5-HT)(2A) receptor induced by agonist or antagonist exposure. Treatment of C6 glioma cells with either 5-HT or the 5-HT(2A) receptor antagonist ketanserin resulted in an attenuation in 5-HT(2A) receptor function, specifically the accumulation of inositol phosphates stimulated by the partial agonist quipazine. 5-HT-induced desensitization of the 5-HT(2A) receptor involved receptor internalization through a clathrin- and dynamin-dependent process because it was prevented by concanavalin A, monodansylcadaverine, and by expression of the dominant negative mutants beta-arrestin (319-418) and dynamin K44A. Although short-term (i.e., 10 min) 5-HT and ketanserin exposure resulted in the same degree of desensitization, ketanserin-induced desensitization was not prevented by these agents and did not involve receptor internalization. In contrast, prolonged ketanserin exposure (i.e., 2 h) resulted in 5-HT(2A) receptor internalization through a clathrin- and dynamin-dependent process, as was observed after agonist treatment. Inhibitors of protein kinase C or calcium-calmodulin kinase II did not attenuate or prevent 5-HT-induced desensitization of the receptor. 5-HT(2A) receptor desensitization induced by 5-HT and prolonged ketanserin treatment, but not by short-term ketanserin treatment, was prevented by the expression of the dominant negative mutant of G protein-coupled receptor kinase (GRK)2, GRK2-K220R, and by an anti-GRK2/3 antibody. Our data indicate a dual mechanism of early and late desensitization by the antagonist ketanserin. Short-term ketanserin treatment reduced the specific binding of the agonist radioligand [(125)I](+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane ([(125)I]DOI) and the ability of 5'-guanylylimidodiphosphate to attenuate this binding, suggesting that at the early stage of antagonist-induced desensitization the capacity of the 5-HT(2A) receptor to couple to G protein is impaired.

eng

IM

MEDLINE

0022-3565

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NLM

468-77

pubmed-meshheading:11805206-Arrestin, pubmed-meshheading:11805206-Clathrin, pubmed-meshheading:11805206-Cyclic AMP-Dependent Protein Kinases, pubmed-meshheading:11805206-Dynamins, pubmed-meshheading:11805206-Enzyme-Linked Immunosorbent Assay, pubmed-meshheading:11805206-GTP Phosphohydrolases, pubmed-meshheading:11805206-GTP-Binding Proteins, pubmed-meshheading:11805206-Guanylyl Imidodiphosphate, pubmed-meshheading:11805206-Humans, pubmed-meshheading:11805206-Hydrolysis, pubmed-meshheading:11805206-Inositol, pubmed-meshheading:11805206-Ketanserin, pubmed-meshheading:11805206-Ligands, pubmed-meshheading:11805206-Receptor, Serotonin, 5-HT2A, pubmed-meshheading:11805206-Receptors, Serotonin, pubmed-meshheading:11805206-Serotonin Antagonists, pubmed-meshheading:11805206-Transfection, pubmed-meshheading:11805206-Tumor Cells, Cultured, pubmed-meshheading:11805206-beta-Adrenergic Receptor Kinases

Mechanisms of ligand-induced desensitization of the 5-hydroxytryptamine(2A) receptor.

Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't