PMID- 16929008 OWN - NLM STAT- MEDLINE DCOM- 20070313 LR - 20211203 IS - 1096-6080 (Print) IS - 1096-0929 (Linking) VI - 94 IP - 1 DP - 2006 Nov TI - Constitutive androstane receptor (CAR) as a potential sensing biomarker of persistent organic pollutants (POPs) in aquatic mammal: molecular characterization, expression level, and ligand profiling in Baikal seal (Pusa sibirica). PG - 57-70 AB - To characterize the function of constitutive active/androstane receptor (CAR) in aquatic mammals, CAR complementary DNA (cDNA) was cloned from the liver of Baikal seal (Pusa sibirica) from Lake Baikal, Russia, and the messenger RNA (mRNA) expression levels in various tissues/organs of the wild population and the CAR ligand profiles were investigated. The seal CAR cDNA had an open reading frame of 1047 bp encoding 348 amino acids that revealed 74-84% amino acid identities with CARs from rodents and human. The mRNA expression profile of tissues/organs represented that Baikal seal CAR was predominantly expressed in the liver followed by heart and intestine. The expression analysis of hepatic CAR mRNA showed no correlation with expression of cytochrome P450 (CYP) 1A, 1B, 2B, 2C, and 3A-like proteins, indicating that the CAR expression level may not be the sole determinant of the regulation of these CYP expressions in the seal liver. There was no significant correlation between CAR expression and any of the persistent organic pollutants (POPs) levels. Furthermore, we performed an in vitro CAR transactivation assay using MCF-7 cells transfected with Baikal seal CAR expression plasmid and (NR1)(3)-luciferase reporter gene plasmid. In the transactivation analysis of Baikal seal CAR, neither repression by androstanol and androstenol, nor activation by estrone and estradiol, which are recognized as endogenous ligands for mouse and human CARs, was detected. On the other hand, bile acids such as chenodeoxycholic acid, deoxycholic acid, and lithocholic acid activated the seal CAR as well as mouse CAR. As for exogenous chemicals, the seal CAR was transactivated by a human CAR agonist, 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime), but not by a mouse CAR agonist, (1,4-bis[2-(3,5-dichloropyridyloxy)]benzene). In addition, the seal CAR was also activated by polychlorinated biphenyls (PCBs) (Kanechlor-500, International Union of Pure and Applied Chemistry No. PCB153; 2,2',4,4',5,5'-hexachlorobiphenyl and PCB180; 2,2',3,4,4',5,5'-heptachlorobiphenyl), and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p'-DDT) and its metabolite, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE). The seal CAR responded more sensitively to PCBs than the mouse CAR. Based on the results of CAR transactivation assay, the lowest observable effect levels of Kanechlor-500, PCB153, PCB180, p,p'-DDT, and p,p'-DDE in Baikal seal were estimated to be 10, 20, 20, 10, and 10 ppm on wet weight basis, respectively. These results suggest that CAR is conserved in diverse mammalian species including seals. Whereas the seal CAR-mediated gene transcription may potentially be a sensitive response to the exposure of certain POPs, the ligand profile of seal CAR may be different from those of other mammalian CARs. This study indicates that CAR-mediated responses may be useful information to assess the ecotoxicological risk of xenobiotics such as POPs in wildlife but the previous results derived from rodent and human CAR may not be applicable to the risk assessment in wild species. FAU - Sakai, Hiroki AU - Sakai H AD - Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama 790-8577, Japan. FAU - Iwata, Hisato AU - Iwata H FAU - Kim, Eun-Young AU - Kim EY FAU - Tsydenova, Oyuna AU - Tsydenova O FAU - Miyazaki, Nobuyuki AU - Miyazaki N FAU - Petrov, Evgeny A AU - Petrov EA FAU - Batoev, Valeriy B AU - Batoev VB FAU - Tanabe, Shinsuke AU - Tanabe S LA - eng SI - GENBANK/AB109553 PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20060823 PL - United States TA - Toxicol Sci JT - Toxicological sciences : an official journal of the Society of Toxicology JID - 9805461 RN - 0 (Biomarkers) RN - 0 (Constitutive Androstane Receptor) RN - 0 (DNA, Complementary) RN - 0 (Ligands) RN - 0 (RNA, Messenger) RN - 0 (Receptors, Cytoplasmic and Nuclear) RN - 0 (Recombinant Fusion Proteins) RN - 0 (Transcription Factors) RN - 0 (Water Pollutants, Chemical) RN - 4M7FS82U08 (Dichlorodiphenyl Dichloroethylene) RN - CIW5S16655 (DDT) RN - DFC2HB4I0K (Polychlorinated Biphenyls) RN - EC 1.13.12.- (Luciferases) SB - IM MH - Amino Acid Sequence MH - Animals MH - Biomarkers/analysis/metabolism MH - Cell Line, Tumor MH - Cloning, Molecular MH - Constitutive Androstane Receptor MH - DDT/pharmacology MH - DNA, Complementary/chemistry/genetics/isolation & purification MH - Dichlorodiphenyl Dichloroethylene/pharmacology MH - Gene Expression Profiling MH - Humans MH - Ligands MH - Luciferases/genetics/metabolism MH - Mice MH - Molecular Sequence Data MH - Phoca/*genetics/metabolism MH - Polychlorinated Biphenyls/pharmacology MH - RNA, Messenger/genetics/metabolism MH - Receptors, Cytoplasmic and Nuclear/agonists/*genetics/metabolism MH - Recombinant Fusion Proteins/genetics/metabolism MH - Reverse Transcriptase Polymerase Chain Reaction MH - Sequence Analysis, DNA MH - Sequence Homology, Amino Acid MH - Transcription Factors/agonists/*genetics/metabolism MH - Transcription, Genetic/drug effects MH - Transfection MH - Water Pollutants, Chemical/*analysis/isolation & purification/pharmacology EDAT- 2006/08/25 09:00 MHDA- 2007/03/14 09:00 CRDT- 2006/08/25 09:00 PHST- 2006/08/25 09:00 [pubmed] PHST- 2007/03/14 09:00 [medline] PHST- 2006/08/25 09:00 [entrez] AID - kfl088 [pii] AID - 10.1093/toxsci/kfl088 [doi] PST - ppublish SO - Toxicol Sci. 2006 Nov;94(1):57-70. doi: 10.1093/toxsci/kfl088. Epub 2006 Aug 23.