Cloning and functional expression of an Aplysia 5-HT receptor negatively coupled to adenylate cyclase.
Serotonin (5-HT) is involved in the control of various behaviors in Aplysia californica, including reproduction, feeding, locomotion, circadian rhythm, synaptic plasticity, and synaptic growth. The large variety of functions of 5-HT is mediated by different receptor subtypes that are coupled to different second-messenger systems. Here, we report the cloning of a cDNA coding for an Aplysia G-protein-coupled 5-HT receptor (5-HTap1). Its deduced amino acid sequence resembles those of the 5-HT1 receptor subfamily. When expressed in stable cell lines, 5-HTap1 exhibits high-affinity binding for the serotonergic radioligand [N-methyl-3H]lysergic acid diethylamide. This binding is competed by several 5-HT agonists and antagonists, and the pharmacological profile of inhibition has some similarities with those of 5-HT1 and 5-HT7 receptors. Application of 5-HT or its agonists 5-carboxamidotryptamine maleate and (+/-)-8-hydroxy-2-(di-n-propyl-amino) tetralin hydrobromide on cells transformed with 5-HTap1 produced a dose-dependent inhibition of forskolin-stimulated cAMP accumulation. 5-HTap1 is thus negatively coupled to adenylate cyclase. The production of antiserum against the 5-HTap1 receptor allowed us to examine its expression in animal tissues. The receptor protein is detected in every tissue examined, although it seems only weakly expressed in some samples. The receptor is also found in every ganglia of the nervous system, both in the sheath and in the neurons. 5-HTap1 mRNA is absent from the sheath, indicating that the protein observed there is probably located on the nerve terminals.
Département de biochimie, Université de Montréal, Montréal, Québec, Canada H3C 3J7.
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Angers
M V
MV
Storozhuk
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Duchaîne
V F
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Castellucci
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DesGroseillers
D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001048:Aplysia / Q000378:metabolism*; D001483:Base Sequence; D001667:Binding, Competitive; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005815:Genetic Code; D008969:Molecular Sequence Data; D010802:Phylogeny; D011985:Receptors, Serotonin / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
D000067956:Adenylyl Cyclase Inhibitors; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D000262:Adenylyl Cyclases