Functional analysis of four naturally occurring variants of human constitutive androstane receptor.
The human constitutive androstane receptor (CAR, NR1I3) is a member of the orphan nuclear receptor superfamily that plays an important role in the control of drug metabolism and disposition. In this study, we sequenced all the coding exons of the NR1I3 gene for 334 Japanese subjects. We identified three novel single nucleotide polymorphisms (SNPs) that induce non-synonymous alterations of amino acids (His246Arg, Leu308Pro, and Asn323Ser) residing in the ligand-binding domain of CAR, in addition to the Val133Gly variant, which was another CAR variant identified in our previous study. We performed functional analysis of these four naturally occurring CAR variants in COS-7 cells using a CYP3A4 promoter/enhancer reporter gene that includes the CAR responsive elements. The His246Arg variant caused marked reductions in both transactivation of the reporter gene and in the response to 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime (CITCO), which is a human CAR-specific agonist. The transactivation ability of the Leu308Pro variant was also significantly decreased, but its responsiveness to CITCO was not abrogated. The transactivation ability and CITCO response of the Val133Gly and Asn323Ser variants did not change as compared to the wild-type CAR. These data suggest that the His246Arg and Leu308Pro variants, especially His246Arg, may influence the expression of drug-metabolizing enzymes and transporters that are transactivated by CAR.
Project term for Pharmacogenetics, National Institute of Health Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan.
Shinobu
S
Ikeda
Kouichi
K
Kurose
Hideto
H
Jinno
Kimie
K
Sai
Shogo
S
Ozawa
Ryuichi
R
Hasegawa
Kazuo
K
Komamura
Takeshi
T
Kotake
Hideki
H
Morishita
Shiro
S
Kamakura
Masafumi
M
Kitakaze
Hitonobu
H
Tomoike
Tomohide
T
Tamura
Noboru
N
Yamamoto
Hideo
H
Kunitoh
Yasuhide
Y
Yamada
Yuichiro
Y
Ohe
Yasuhiro
Y
Shimada
Kuniaki
K
Shirao
Kaoru
K
Kubota
Hironobu
H
Minami
Atsushi
A
Ohtsu
Teruhiko
T
Yoshida
Nagahiro
N
Saijo
Yoshiro
Y
Saito
Jun-ichi
J
Sawada
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D000090702:Constitutive Androstane Receptor; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D006801:Humans; D010957:Plasmids; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation
D000090702:Constitutive Androstane Receptor; C000716327:NR1I3 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; D003577:Cytochrome P-450 Enzyme System; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human