Characterization of the porcine constitutive androstane receptor (CAR) and its splice variants.
Porcine constitutive androstane receptor (CAR; NR1I3) was cloned and compared for homology and activity with mouse and human CAR (mCAR, hCAR). Porcine CAR (pgCAR) was 86% and 75% homologous to hCAR at the nucleotide and protein levels. Five alternatively spliced variants of pgCAR were identified, each of which generated a truncated protein product. Real-time polymerase chain reaction (PCR) analyses showed that these variants were present in pig liver cDNA samples from 4.61% to 9.20% of total pgCAR. pgCAR and hCAR responded similarly to more ligands than did hCAR and mCAR. The known hCAR agonist (6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl)oxime (CITCO) activated pgCAR, while the murine agonist 1,4 bis[2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP) had no effect. 5beta-dihydrotestosterone was identified as a novel inverse agonist of both pgCAR and hCAR. pgCAR splice variant 2 (SV2) had a dose-dependent dominant negative effect on the activity of wild-type pgCAR in dual luciferase assays. SV2 had no effect against pgPXR (pregnane X receptor) or pgFXR (farnesoid X receptor) activity when using PXR- or FXR-specific reporters.
Gray
M A
MA
Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada.
Peacock
J N
JN
Squires
E J
EJ
D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D000090702:Constitutive Androstane Receptor; D005091:Exons / Q000235:genetics; D006801:Humans; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D034421:Sus scrofa / Q000235:genetics*; D014162:Transfection
D000090702:Constitutive Androstane Receptor; D008024:Ligands; C000716327:NR1I3 protein, human; C000716328:Nr1i3 protein, mouse; D020033:Protein Isoforms; D018160:Receptors, Cytoplasmic and Nuclear