scholarly journals Relative Activation of Human Pregnane X Receptor versus Constitutive Androstane Receptor Defines Distinct Classes of CYP2B6 and CYP3A4 Inducers

2006 ◽  
Vol 320 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Stephanie R. Faucette ◽  
Tong-Cun Zhang ◽  
Rick Moore ◽  
Tatsuya Sueyoshi ◽  
Curtis J. Omiecinski ◽  
...  
Keyword(s):  
Constitutive Androstane Receptor ◽  
Pregnane X Receptor ◽  
Relative Activation

Regulatory Cross-Talk between Drug Metabolism and Lipid Homeostasis: Constitutive Androstane Receptor and Pregnane X Receptor Increase Insig-1 Expression

2008 ◽  
Vol 73 (4) ◽  
pp. 1282-1289 ◽  
Author(s):  
Adrian Roth ◽  
Renate Looser ◽  
Michel Kaufmann ◽  
Sharon M. Blättler ◽  
Franck Rencurel ◽  
...  
Keyword(s):  
Drug Metabolism ◽  
Cross Talk ◽  
Constitutive Androstane Receptor ◽  
Pregnane X Receptor ◽  
Lipid Homeostasis

scholarly journals Constitutive androstane receptor and pregnane X receptor cooperatively ameliorate DSS-induced colitis

2019 ◽  
Vol 51 (2) ◽  
pp. 226-235 ◽  
Author(s):  
Daisuke Uehara ◽  
Hiroki Tojima ◽  
Satoru Kakizaki ◽  
Yuichi Yamazaki ◽  
Norio Horiguchi ◽  
...  
Keyword(s):  
Constitutive Androstane Receptor ◽  
Pregnane X Receptor

scholarly journals Evolutionary Plasticity in Detoxification Gene Modules: The Preservation and Loss of the Pregnane X Receptor in Chondrichthyes Lineages

2019 ◽  
Vol 20 (9) ◽  
pp. 2331 ◽  
Author(s):  
Elza S. S. Fonseca ◽  
Raquel Ruivo ◽  
André M. Machado ◽  
Francisca Conrado ◽  
Boon-Hui Tay ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Constitutive Androstane Receptor ◽  
Pregnane X Receptor ◽  
Gene Families ◽  
Critical Question ◽  
Group I ◽  
Activation Profile ◽  
Gene Duplication And Loss ◽  
Molecular Landscape ◽  
Gene Orthologs

To appraise how evolutionary processes, such as gene duplication and loss, influence an organism’s xenobiotic sensitivity is a critical question in toxicology. Of particular importance are gene families involved in the mediation of detoxification responses, such as members of the nuclear receptor subfamily 1 group I (NR1I), the pregnane X receptor (PXR), and the constitutive androstane receptor (CAR). While documented in multiple vertebrate genomes, PXR and CAR display an intriguing gene distribution. PXR is absent in birds and reptiles, while CAR shows a tetrapod-specific occurrence. More elusive is the presence of PXR and CAR gene orthologs in early branching and ecologically-important Chondrichthyes (chimaeras, sharks and rays). Therefore, we investigated various genome projects and use them to provide the first identification and functional characterization of a Chondrichthyan PXR from the chimaera elephant shark (Callorhinchus milii, Holocephali). Additionally, we substantiate the targeted PXR gene loss in Elasmobranchii (sharks and rays). Compared to other vertebrate groups, the chimaera PXR ortholog displays a diverse expression pattern (skin and gills) and a unique activation profile by classical xenobiotic ligands. Our findings provide insights into the molecular landscape of detoxification mechanisms and suggest lineage-specific adaptations in response to xenobiotics in gnathostome evolution.

scholarly journals Comparison of the Hepatic Effects of Phenobarbital in Chimeric Mice Containing Either Rat or Human Hepatocytes With Humanized Constitutive Androstane Receptor and Pregnane X Receptor Mice

2020 ◽  
Vol 177 (2) ◽  
pp. 362-376
Author(s):  
Tomoya Yamada ◽  
Ayako Ohara ◽  
Naoya Ozawa ◽  
Keiko Maeda ◽  
Miwa Kondo ◽  
...  
Keyword(s):  
Gene Expression ◽  
Liver Tumor ◽  
Constitutive Androstane Receptor ◽  
Pregnane X Receptor ◽  
Rat Hepatocytes ◽  
Global Gene Expression ◽  
Human Hepatocytes ◽  
Chimeric Mouse ◽  
Chimeric Mice ◽  
Wild Type

Abstract Using a chimeric mouse humanized liver model, we provided evidence that human hepatocytes are refractory to the mitogenic effects of rodent constitutive androstane receptor (CAR) activators. To evaluate the functional reliability of this model, the present study examined mitogenic responses to phenobarbital (PB) in chimeric mice transplanted with rat hepatocytes, because rats are responsive to CAR activators. Treatment with 1000 ppm PB for 7 days significantly increased replicative DNA synthesis (RDS) in rat hepatocytes of the chimeric mice, demonstrating that the transplanted hepatocyte model is functionally reliable for cell proliferation analysis. Treatment of humanized CAR and pregnane X receptor (PXR) mice (hCAR/hPXR mice) with 1000 ppm PB for 7 days significantly increased hepatocyte RDS together with increases in several mitogenic genes. Global gene expression analysis was performed with liver samples from this and from previous studies focusing on PB-induced Wnt/β-catenin signaling and showed that altered genes in hCAR/hPXR mice clustered most closely with liver tumor samples from a diethylnitrosamine/PB initiation/promotion study than with wild-type mice. However, different gene clusters were observed for chimeric mice with human hepatocytes for Wnt/β-catenin signaling when compared with those of hCAR/hPXR mice, wild-type mice, and liver tumor samples. The results of this study demonstrate clear differences in the effects of PB on hepatocyte RDS and global gene expression between human hepatocytes of chimeric mice and hCAR/hPXR mice, suggesting that the chimeric mouse model is relevant to humans for studies on the hepatic effects of rodent CAR activators whereas the hCAR/hPXR mouse is not.

scholarly journals Pharmacological Activation of PXR and CAR Downregulates Distinct Bile Acid-Metabolizing Intestinal Bacteria and Alters Bile Acid Homeostasis

2018 ◽  
Vol 168 (1) ◽  
pp. 40-60 ◽  
Author(s):  
Joseph L Dempsey ◽  
Dongfang Wang ◽  
Gunseli Siginir ◽  
Qiang Fei ◽  
Daniel Raftery ◽  
...  
Keyword(s):  
Bile Acid ◽  
Gut Microbiota ◽  
Gut Microbiome ◽  
Corn Oil ◽  
Constitutive Androstane Receptor ◽  
Intestinal Bacteria ◽  
Pregnane X Receptor ◽  
Bile Salt Hydrolase ◽  
Dependent Manner ◽  
Germ Free

AbstractThe gut microbiome regulates important host metabolic pathways including xenobiotic metabolism and intermediary metabolism, such as the conversion of primary bile acids (BAs) into secondary BAs. The nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are well-known regulators for xenobiotic biotransformation in liver. However, little is known regarding the potential effects of PXR and CAR on the composition and function of the gut microbiome. To test our hypothesis that activation of PXR and CAR regulates gut microbiota and secondary BA synthesis, 9-week-old male conventional and germ-free mice were orally gavaged with corn oil, PXR agonist PCN (75 mg/kg), or CAR agonist TCPOBOP (3 mg/kg) once daily for 4 days. PCN and TCPOBOP decreased two taxa in the Bifidobacterium genus, which corresponded with decreased gene abundance of the BA-deconjugating enzyme bile salt hydrolase. In liver and small intestinal content of germ-free mice, there was a TCPOBOP-mediated increase in total, primary, and conjugated BAs corresponding with increased Cyp7a1 mRNA. Bifidobacterium, Dorea, Peptociccaceae, Anaeroplasma, and Ruminococcus positively correlated with T-UDCA in LIC, but negatively correlated with T-CDCA in serum. In conclusion, PXR and CAR activation downregulates BA-metabolizing bacteria in the intestine and modulates BA homeostasis in a gut microbiota-dependent manner.

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