title: Molecular and pharmacological characterization of zebrafish 'contractile' and 'inhibitory' prostanoid receptors.
abstract: Prostanoids comprising prostaglandins (PGs) and thromboxanes (TXs) have been shown to play physiological and pathological roles in zebrafish. However, the molecular basis of zebrafish prostanoid receptors has not been established. Here, we demonstrate that there exist at least five 'contractile' (Ca(2+)-mobilizing) and one 'inhibitory' (Gi-coupled) prostanoid receptors in zebrafish; five 'contractile' receptors consisting of two PGE2 receptors (EP1a and EP1b), two PGF2α receptors (FP1 and FP2), and one TXA2 receptor TP, and one 'inhibitory' receptor, the PGE2 receptor EP3. [(3)H]PGE2 specifically bound to the membranes of cells expressing zebrafish EP1a, EP1b and EP3 with a Kd of 4.8, 1.8 and 13.6nM, respectively, and [(3)H]PGF2α specifically bound to the membranes of cells expressing zebrafish FP1 and FP2, with a Kd of 6.5 and 1.6nM, respectively. U-46619, a stable agonist for human and mouse TP receptors, significantly increased the specific binding of [(35)S]GTPγS to membranes expressing the zebrafish TP receptor. Upon agonist stimulation, all six receptors showed an increase in intracellular Ca(2+) levels, although the increase was very weak in EP1b, and pertussis toxin abolished only the EP3-mediated response. Zebrafish EP3 receptor also suppressed forskolin-induced cAMP formation in a pertussis toxin-sensitive manner. In association with the low structural conservation with mammalian receptors, most agonists and antagonists specific for mammalian EP1, EP3 and TP failed to work on each corresponding zebrafish receptor. This work provides further insights into the diverse prostanoid actions mediated by their receptors in zebrafish.
authors.affiliation: Department of Pharmaceutical Biochemistry, Graduate School of Pharmaceutical Sciences, Kumamoto University, Chuo-ku, Kumamoto 862-0973, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Iwasaki
authors.forename: Kyoshiro
authors.initials: K
authors.lastname: Tsuge
authors.forename: Kazushi
authors.initials: K
authors.lastname: Morimoto
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Inazumi
authors.forename: Osamu
authors.initials: O
authors.lastname: Kawahara
authors.forename: Atsuo
authors.initials: A
authors.lastname: Kawahara
authors.forename: Soken
authors.initials: S
authors.lastname: Tsuchiya
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Sugimoto
mesh_terms: D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D005576:Colforsin / Q000494:pharmacology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D037342:Pertussis Toxin / Q000737:chemistry; D010802:Phylogeny; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D011982:Receptors, Prostaglandin / Q000378:metabolism*; D058308:Receptors, Prostaglandin E, EP3 Subtype / Q000378:metabolism; D017482:Receptors, Thromboxane / Q000378:metabolism; D015398:Signal Transduction; D014018:Tissue Distribution; D015027:Zebrafish / Q000502:physiology*; D029961:Zebrafish Proteins / Q000378:metabolism*
chemical_list: D043562:Receptors, G-Protein-Coupled; D011982:Receptors, Prostaglandin; D058308:Receptors, Prostaglandin E, EP3 Subtype; D017482:Receptors, Thromboxane; D029961:Zebrafish Proteins; D005576:Colforsin; D037342:Pertussis Toxin; D002118:Calcium
keywords: GPCR; Pharmacology; Prostaglandins; Signal transduction; Thromboxanes