title: The endothelin/sarafotoxin-induced increase of the proliferation of undifferentiated and DMSO-differentiated GEM-81 goldfish erythrophoroma cells is mediated by ETB receptors.
abstract: Endothelins (ETs) and sarafotoxins (SRTXs) have been reported to exert ET(B)-mediated effects on vertebrate pigment cells. GEM-81 cell line, a red pigment cell-derived cutaneous tumor of the teleost Carassius auratus, expresses ET(B) receptors and can be differentiated with 1.5% DMSO treatment, thus constituting an useful model to investigate ET and SRTX effects on cultured fish pigment cells. Our aim was to characterize the pharmacology and biological effects mediated by ET receptors in DMSO-differentiated and undifferentiated cells. ET subtype receptors and their respective Ki values in both cell types were determined by competitive binding assays using (125)I ET-1 and BQ-485 (an ET(A) antagonist) or BQ-788 (an ET(B) antagonist). BQ-788, but not BQ-485, significantly reduced (125)I-ET-1 binding in both cell types, with similar low (Ki > nM) affinities. To determine the proliferation effects of ETs/SRTXs, cells were treated for 72 h with the hormones, and counted in a hemocytometer. The proliferation assays were repeated for SRTX S6c in the presence or absence of BQ-788. The results demonstrated that, with the exception of ET-1 (biphasic effect) and ET-3 (no significant effect) in undifferentiated GEM-81 cells, all the tested hormones induced increases in the proliferation of both types of cells. The hormones were equipotent in DMSO-differentiated cells, which exhibited increased sensitivity to ETs, but not to SRTXs, as compared with undifferentiated cells. The BQ-788 antagonistic effect was also exerted on the proliferation responses to SRTX S6c. These results corroborate the long and important evolutionary history of the ET/SRTX receptor system in vertebrate pigment cells.
authors.affiliation: Departamento de Fisiologia, Setor de Ciências Biológicas, Centro Politécnico, Universidade Federal do Paraná, R. Francisco H. dos Santos, s/n Jardim das Américas, CEP 81540-970, Paraná, Brazil. anamfila@ufpr.br
authors.forename: Ana Maria Caliman
authors.initials: AM
authors.lastname: Filadelfi
authors.forename: Guilherme Corrêa
authors.initials: GC
authors.lastname: Ramanzini
authors.forename: Maria Aparecida
authors.initials: MA
authors.lastname: Visconti
authors.forename: Ana Maria de Lauro
authors.initials: AM
authors.lastname: Castrucci
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001381:Azepines / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism*; D019334:Endothelin-3 / Q000378:metabolism*; D006054:Goldfish / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000378:metabolism / Q000494:pharmacology*; D014757:Viper Venoms / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000959:Antihypertensive Agents; D001381:Azepines; D003451:Cryoprotective Agents; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1; D019334:Endothelin-3; D009842:Oligopeptides; D010880:Piperidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D014662:Vasoconstrictor Agents; D014757:Viper Venoms; C057354:sarafotoxins s6; C083116:BQ 485; C086539:BQ 788; D004121:Dimethyl Sulfoxide