title: An endothelin type A receptor-expressing cell to characterize endothelin-1 binding and screen antagonist.
abstract: Endothelin-1 (ET-1) induces contraction of vascular smooth muscle through binding to endothelin type A receptor (ET(A)R). COS-7 cells stably expressing high levels of the ET(A)R were established (designated COS-7(ET(A)R)). The COS-7(ET(A)R) cell bound [(125)I]ET-1 with a K(d) of 932+/-161 pM and a B(max) of 74+/-13 fmol/2x10(5) cells. [(125)I]ET-1 binding was inhibited by ET-1 and the ET(A)R antagonist BQ-610, but not by the endothelin type B receptor (ET(B)R) antagonist BQ-788. In clones expressing two ET(A)R mutants containing D46N or R53Q substitutions in the first extracellular domain of the receptor, [(125)I]ET-1 binding activity was dramatically reduced. This suggests that these single amino acid substitutions alter the three-dimensional structure of the ligand-binding domain of the ET(A)R. Using COS-7(ET(A)R) cell, we showed that Ca(2+) or Mg(2+) was essential for ET-1 binding to the ET(A)R and that ET-1 treatment induced postreceptor signaling, that is, intracellular accumulation of cyclic AMP (cAMP) and Ca(2+) mobilization. The COS-7(ET(A)R) established in this study will be a useful tool for screening ET-1 antagonists for treating hypertension.
authors.affiliation: Institute of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China.
authors.forename: Chi-Chang
authors.initials: CC
authors.lastname: Juan
authors.forename: Lo-Chun
authors.initials: LC
authors.lastname: Au
authors.forename: Feng-Yuan
authors.initials: FY
authors.lastname: Yang
authors.forename: De-Ming
authors.initials: DM
authors.lastname: Yang
authors.forename: Low-Tone
authors.initials: LT
authors.lastname: Ho
mesh_terms: D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000378:metabolism; D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology; D011485:Protein Binding; D044022:Receptor, Endothelin A / Q000235:genetics / Q000378:metabolism
chemical_list: D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D019332:Endothelin-1; D009842:Oligopeptides; D010880:Piperidines; D044022:Receptor, Endothelin A; C087220:BQ 610; C086539:BQ 788; D000242:Cyclic AMP; D008274:Magnesium; D002118:Calcium