Multivalent ligand-receptor interactions elicit inverse agonist activity of AT(1) receptor blockers against stretch-induced AT(1) receptor activation.
Type 1 angiotensin II (AT(1)) receptor has a critical role in the development of load-induced cardiac hypertrophy. Recently, we showed that mechanical stretching of cells activates the AT(1) receptor without the involvement of angiotensin II (AngII) and that this AngII-independent activation is inhibited by the inverse agonistic activity of the AT(1) receptor blocker (ARB), candesartan. Although the inverse agonist activity of ARBs has been studied in terms of their action on constitutively active AT(1) receptors, the structure-function relationship of the inverse agonism they exert against stretch-induced AT(1) receptor activation has not been fully elucidated. Assays evaluating c-fos gene expression and phosphorylated extracellular signal-regulated protein kinases (ERKs) have shown that olmesartan has strong inverse agonist activities against the constitutively active AT(1) receptor and the stretch-induced activation of AT(1) receptor, respectively. Ternary drug-receptor interactions, which occur between the hydroxyl group of olmesartan and Tyr(113) and between the carboxyl group of olmesartan and Lys(199) and His(256), were essential for the potent inverse agonist action olmesartan exerts against stretch-induced ERK activation and the constitutive activity of the AT(1)-N111G mutant receptor. Furthermore, the inverse agonist activity olmesartan exerts against stretch-induced ERK activation requires an additional drug-receptor interaction involving the tetrazole group of olmesartan and Gln(257) of the AT(1) receptor. These results suggest that multivalent interactions between an inverse agonist and the AT(1) receptor are required to stabilize the receptor in an inactive conformation in response to the distinct processes that lead to an AngII-independent activation of the AT(1) receptor.
Qin
Yingjie
Y
Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chuo-ku, Chiba, Japan.
Yasuda
Noritaka
N
Akazawa
Hiroshi
H
Ito
Kaoru
K
Kudo
Yoko
Y
Liao
Chien-Hui
CH
Yamamoto
Rie
R
Miura
Shin-Ichiro
S
Saku
Keijiro
K
Komuro
Issei
I
D047228:Angiotensin II Type 1 Receptor Blockers / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000737:chemistry / Q000494:pharmacology; D066298:In Vitro Techniques; D008024:Ligands; D019808:Losartan; D009154:Mutation; D032383:Myocytes, Cardiac / Q000187:drug effects*; D016760:Proto-Oncogene Proteins c-fos / Q000502:physiology; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D051381:Rats; D017208:Rats, Wistar; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D013329:Structure-Activity Relationship; D013777:Tetrazoles / Q000737:chemistry / Q000494:pharmacology
D047228:Angiotensin II Type 1 Receptor Blockers; D007093:Imidazoles; D008024:Ligands; D016760:Proto-Oncogene Proteins c-fos; D044140:Receptor, Angiotensin, Type 1; D013777:Tetrazoles; D012313:RNA; C437965:olmesartan; D048049:Extracellular Signal-Regulated MAP Kinases; D019808:Losartan