Ligand binding and functional properties of human angiotensin AT1 receptors in transiently and stably expressed CHO-K1 cells.
Chinese Hamster Ovary Cells (CHO-K1) were transiently and stably transfected to express the human angiotensin AT(1) receptor. Cell surface receptor expression was maximal 2 days after transient transfection. Their pharmacological and signalling properties differed from stably expressed receptors. Receptor reserve was significant in the transient cells but not in stable cells, explaining the higher potency of angiotensin II and the lower degree of insurmountable inhibition by candesartan in the transient cells. [Sar(1)Ile(8)]angiotensin II (sarile) is a potent angiotensin AT(1) receptor antagonist for the stable cells but is a partial agonist, producing 19% of the maximal response by angiotensin II, in transient cells. Internalization of [(3)H]angiotensin II and [(125)I]sarile (i.e., acid-resistant binding) was more pronounced in stable cells. CHO-K1 cells were also transiently transfected with the enhanced green fluorescence-AT(1) receptor gene. Confocal microscopy revealed rapid internalization induced by angiotensin II and sarile but not by candesartan. The above disparities may result from differences in receptor maturation and/or cellular surrounding.
Le
Minh Tam
MT
Department of Molecular and Biochemical Pharmacology, Institute for Molecular Biology and Biotechnology, Vrije Universiteit Brussel (VUB), Belgium. tmleminh@vub.ac.be
De Backer
Jean-Paul
JP
Hunyady
László
L
Vanderheyden
Patrick M L
PM
Vauquelin
Georges
G
D015059:1-Sarcosine-8-Isoleucine Angiotensin II / Q000378:metabolism / Q000494:pharmacology; D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001562:Benzimidazoles / Q000378:metabolism / Q000494:pharmacology; D001667:Binding, Competitive / Q000187:drug effects; D001713:Biphenyl Compounds; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D008024:Ligands; D018613:Microscopy, Confocal; D011869:Radioligand Assay; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013777:Tetrazoles / Q000378:metabolism / Q000494:pharmacology; D014162:Transfection; D014316:Tritium
D047228:Angiotensin II Type 1 Receptor Blockers; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D007295:Inositol Phosphates; D008024:Ligands; D044140:Receptor, Angiotensin, Type 1; D011993:Recombinant Fusion Proteins; D013777:Tetrazoles; D014316:Tritium; D000804:Angiotensin II; D049452:Green Fluorescent Proteins; D015059:1-Sarcosine-8-Isoleucine Angiotensin II; C081643:candesartan