title: Identification and characterization of novel alternative splice variants of human constitutive androstane receptor in liver samples of Koreans and Caucasians.
abstract: Human constitutive androstane receptor (hCAR, NR1I3) is a member of the orphan nuclear receptor family and regulates the transcription of many drug-metabolizing enzymes and drug transporters. Previous studies have shown that the hCAR gene produces a number of different kinds of mRNA splicing variants (SVs) in non-Asian ethnicities. In the present study, we identified 18 hCAR SVs (SV1-SV18), including four novel SVs in Korean human livers. Among the four novel SVs, SV2 showed enhanced transactivation activity when cotransfected with CYP2B6 reporter gene, whereas other SVs were nonfunctional. When profiles of major hCAR SVs were compared among 30 livers from Korean patients and 20 livers from Caucasian patients, the relative composition of each SV showed interethnic variation as well as interindividual variation. The most predominant form of hCAR SV was not wild type, but either SV4 or SV7. The summed relative amounts of SV4 and SV7 ranged from 34.5 to 57.6% in the 30 Korean livers and from 47.2 to 82.6% in the 20 Caucasian livers, suggesting large interindividual variation. The mean relative amount of nonfunctional SV9 was significantly higher in Koreans (29.8%) than in Caucasians (12.8%). The mean relative amount of novel SV2 was 9.7% in Korean livers and 3.5% in Caucasian livers. Expression profiling of hCAR proteins in human livers also supported large interindividual variation in the expressional ratio of wild-type and SVs. Our results describe for the first time the direct comparison of hCAR SV profiles between Koreans and Caucasians. The functional relevance of these interindividual and interethnic variations of hCAR mRNA expression needs to be further characterized.
authors: Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Paik Hospital, Busan, Republic of Korea.
authors: Eun-Jung
authors: EJ
authors: Choi
authors: Yin-Jin
authors: YJ
authors: Jang
authors: Eun-Young
authors: EY
authors: Cha
authors: Jae-Gook
authors: JG
authors: Shin
authors: Sang Seop
authors: SS
authors: Lee
mesh_terms: D000328:Adult; D000368:Aged; D017398:Alternative Splicing / Q000235:genetics*; D044466:Asian People / Q000235:genetics*; D000090702:Constitutive Androstane Receptor; D005260:Female; D020869:Gene Expression Profiling; D056945:Hep G2 Cells; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics*; D044465:White People / Q000235:genetics*
chemical_list: D000090702:Constitutive Androstane Receptor; C000716327:NR1I3 protein, human; D018160:Receptors, Cytoplasmic and Nuclear