Project description:Purpose: To explore the role of PXR signaling in regulating macrophage transcriptome related to atherogenesis Methods: Peritoneal macrophages were isolated from LDLR knockout mice with myeloid specific PXR deficiency (PXRΔMyeLDLR-/-) and their littermates (PXRF/FLDLR-/-). Then the macrophages were treated with a PXR ligand PCN or DMSO control for 12 hr. Total RNA was extracted for RNAseq Results: PCN-mediated PXR activation induced 439 differentially expressed genes (DEGs) with false discovery rate (FDR) < 5% and fold change >1.5 in control macrophages. By contrast, PCN only induced 38 DEFs in PXR-deficient macrophages. Conclusions: These results indicate that PXR signaling may affect many genes in macrophages related atherosclerosis development.
Project description:Purpose: to investigate transcriptomal differences between wild-type and SXR/PXR knockout mice and the impact of PCB-153 exposure to both strains to help reveal the mechanism behind the phenotype of hemolytic anemia observed in SXR knockout mice exposed to PCB-153
Project description:The nuclear pregnane X receptor (PXR) regulates the expression of genes involved in the metabolism, hepatobiliary disposition, and toxicity of drugs and endogenous compounds. PXR is a promiscuous nuclear hormone receptor (NHR) with significant ligand and DNA-binding crosstalk with the constitutive androstane receptor (CAR); hence, defining the precise role of PXR in gene regulation is challenging. Here, utilising a novel PXR-knockout (KO) HepaRG cell line, real-time PCR analysis was conducted to determine PXR involvement for a range of inducers. The selective PXR agonist rifampicin, a selective CAR activator, 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime (CITCO), and dual activators of CAR and PXR including phenobarbital (PB) were analyzed. HepaRG control cells (5F clone) were responsive to prototypical inducers of CYP2B6 and CYP3A4. No response was observed in the PXR-KO cells treated with rifampicin. Induction of CYP3A4 by PB, artemisinin, and phenytoin was also much reduced in PXR-KO cells, while the response to CITCO was maintained. This finding is in agreement with the abolition of functional PXR expression. The apparent EC50 values for PB were in agreement between the cell lines; however, CITCO was ~threefold (0.3 μmol/L vs. 1 μmol/L) lower in the PXR-KO cells compared with the 5F cells for CYP2B6 induction. Results presented support the application of the novel PXR-KO cells in the definitive assignment of PXR-mediated CYP2B6 and CYP3A4 induction. Utilization of such cell lines will allow advancement in composing structure activity relationships rather than relying predominantly on pharmacological manipulations and provide in-depth mechanistic evaluation.
Project description:Background: Cisplatin-induced acute kidney injury (CAKI) has been recognized as one of the most serious side effects of cisplatin. Pregnane X receptor (PXR) is a ligand-dependent nuclear receptor and serves as a master regulator of xenobiotic detoxification. Increasing evidence also suggests PXR has many nonxenobiotic functions including the regulation of cell proliferation, inflammatory response and glucose and lipid metabolism. Methods: In this study, we aimed to investigate the role of PXR in cisplatin-induced nephrotoxicity. CAKI model was performed in wild-type or PXR knockout mice. Pregnenolone 16α-carbonitrile (PCN), a mouse PXR specific agonist, was used for PXR activation. The renal function, biochemical, histopathological and molecular alterations were examined in mouse blood, urine or renal tissues. Whole transcriptome analysis was performed by RNA sequencing. Dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays were applied to determine the regulation of PXR on its target genes. Results: We found that PXR activation significantly attenuated CAKI as reflected by improved renal function, reduced renal tubular apoptosis, ameliorated oxidative and endoplasmic reticulum stress, and suppressed inflammatory factor expression. RNA sequencing analysis revealed that the renoprotective effect of PXR was associated with multiple crucial signaling pathways. In particular, PXR protected against cisplatin-induced AKI by the activation of PI3K/AKT pathway and the induction of multidrug and toxin extrusion 1 (MATE1), an important transporter mediating cellular excretion of cisplatin, in the kidney. Conclusions: Our results demonstrate that PXR activation can preserve renal function in cisplatin-induced AKI and suggest a possibility of PXR as a novel therapeutic target for cisplatin-induced nephrotoxicity.
Project description:To investigate the role of the nuclear receptors CAR (constitutive androstane receptor) and PXR (Pregnane X receptor) in mediating the effects of non-genotoxic carcinogens, groups of mice humanised or deleted for CAR and PXR were treated with 1,4-Dichlorobenzene or cyproterone acetate for 3d and liver tissue harvested for expression profiling. Control groups were treated with appropriate vehicles.
Project description:Many environmentally-relevant chemicals and drugs activate the nuclear receptor pregnane X receptor (PXR). Activation of PXR can lead to increases in liver weight in part through hepatocyte replication similar to a large number of compounds that activate other nuclear receptors such as the peroxisome proliferator-activated receptor alpha and the constitutive activated receptor (CAR). PXR controls the expression of a large battery of genes involved in xenobiotic metabolism. Identification of genes that are accurate predictors of PXR activation would be useful in high-throughput screens to assess potential toxicity and drug-drug interactions. Here, we identified PXR-dependent genes in the mouse liver after exposure to pregnenolone 16alpha-carbinonitrile (PCN), a chemical that is often used as a model PXR agonist.
Project description:The objective of the present study is to examine the potential role of the pregnane x receptor (PXR) in mice treated with an small molecule inhibitor for beta-secretase (CMP013) Two groups of mice, C57Bl/6 (PXR+/+) and PXR-knockout C57Bl/6NTac (PXR-/-), were administered either CMP013 or vehicle. There were five animals per treatment group for each strain. After 96 h, all animals were euthanized, and liver samples were collected for RNA. extraction.
Project description:Pregnane X receptor (PXR), a xenobiotic receptor involved in drug metabolism, has been reported to regulate lipid and glucose metabolism. The intestine tract is the first inner barrier of the body, which dysfunction contributes to the development of metabolic disorders. However, the role of intestinal PXR in metabolic diseases remains largely unknown. In this study, we showed that activation of PXR by tributyl citrate (TBC), an intestinal-selective agonist of PXR, improved high fat diet (HFD)-induced obesity and insulin resistance. The metabolic benefit of intestinal PXR activation was associated with upregulation of β-1,3 galactosyltransferase 5 (B3galt5). Our results revealed that B3galt5 is mainly expressed in the intestine and is a direct transcriptional target of PXR. Whole-body and intestine-specific knockout of B3galt5 exacerbated HFD-induced obesity, insulin resistance and inflammation. Mechanistically, B3galt5 is essential to maintain the integrity of intestinal mucus barrier. Ablation of B3galt5 impaired the O-glycosylation of mucin2, destabilized the mucus layer, and increased the permeability of intestinal barrier. Furthermore, B3galt5 deficiency abolished the beneficial effect of intestinal PXR activation on metabolic disorders. Our results suggested the intestinal-selective activation of PXR regulated B3galt5 expression holds an important role in maintaining metabolic homeostasis, making it a potential therapeutic strategy in obesity.
Project description:Pregnane X receptor (PXR), a xenobiotic receptor involved in drug metabolism, has been reported to regulate lipid and glucose metabolism. The intestine tract is the first inner barrier of the body, which dysfunction contributes to the development of metabolic disorders. However, the role of intestinal PXR in metabolic diseases remains largely unknown. In this study, we showed that activation of PXR by tributyl citrate (TBC), an intestinal-selective agonist of PXR, improved high fat diet (HFD)-induced obesity and insulin resistance. The metabolic benefit of intestinal PXR activation was associated with upregulation of β-1,3 galactosyltransferase 5 (B3galt5). Our results revealed that B3galt5 is mainly expressed in the intestine and is a direct transcriptional target of PXR. Whole-body and intestine-specific knockout of B3galt5 exacerbated HFD-induced obesity, insulin resistance and inflammation. Mechanistically, B3galt5 is essential to maintain the integrity of intestinal mucus barrier. Ablation of B3galt5 impaired the O-glycosylation of mucin2, destabilized the mucus layer, and increased the permeability of intestinal barrier. Furthermore, B3galt5 deficiency abolished the beneficial effect of intestinal PXR activation on metabolic disorders. Our results suggested the intestinal-selective activation of PXR regulated B3galt5 expression holds an important role in maintaining metabolic homeostasis, making it a potential therapeutic strategy in obesity.