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:Several drugs induce liver steatosis through pregnane X receptor (PXR)-mediated mechanism. Atorvastatin is a PXR ligand but is still safe even in patients with metabolic dysfunction-associated steatotic liver disease. To reveal differences between atorvastatin and other PXR ligands, we characterized the effect of atorvastatin on PXR-mediated gene regulation and liver steatosis in mice. Mice were treated orally with atorvastatin, a classical PXR ligand pregnenolone 16α-carbonitrile (PCN), or pravastatin, a statin not activating PXR. Atorvastatin treatment was also performed in PXR knockout mice. Analysis of liver transcriptomics after four-day treatment indicated that atorvastatin regulates genes almost exclusively through PXR. Atorvastatin and PCN regulated partially overlapping, but distinct set of genes and Cyp3a11 was not induced by atorvastatin. Pathway analysis indicated that the atorvastatin treatment predominantly induced genes involved in cholesterol synthesis, while PCN affected pathways involved in growth, proliferation, and steatosis. PCN increased nuclear SREBP1 protein level while atorvastatin increased both SREBP1 and SREBP2. In high-fat diet (HFD)-fed mice, 28-day oral treatment with PCN aggravated diet-induced liver steatosis while atorvastatin had no effect. 28-day atorvastatin treatment reduced the hepatic expression of PXR, and its effect on cholesterol synthesis genes disappeared. PCN did not influence PXR expression, and the Cyp3a11 expression remained induced still after 28 days. Among the lipogenic genes studied, Scd1 was the only one significantly induced by PCN after 28-day treatment in the HFD-fed mice. In summary, atorvastatin regulates mouse liver transcriptomics PXR dependently but differently from PCN and represses PXR in long-term treatment in the HFD-fed mice. Unlike PCN, atorvastatin does not promote liver steatosis.
Project description:Several drugs induce liver steatosis through pregnane X receptor (PXR)-mediated mechanism. Atorvastatin is a PXR ligand but is still safe even in patients with metabolic dysfunction-associated steatotic liver disease. To reveal differences between atorvastatin and other PXR ligands, we characterized the effect of atorvastatin on PXR-mediated gene regulation and liver steatosis in mice. Mice were treated orally with atorvastatin, a classical PXR ligand pregnenolone 16α-carbonitrile (PCN), or pravastatin, a statin not activating PXR. Atorvastatin treatment was also performed in PXR knockout mice. Analysis of liver transcriptomics after four-day treatment indicated that atorvastatin regulates genes almost exclusively through PXR. Atorvastatin and PCN regulated partially overlapping, but distinct set of genes and Cyp3a11 was not induced by atorvastatin. Pathway analysis indicated that the atorvastatin treatment predominantly induced genes involved in cholesterol synthesis, while PCN affected pathways involved in growth, proliferation, and steatosis. PCN increased nuclear SREBP1 protein level while atorvastatin increased both SREBP1 and SREBP2. In high-fat diet (HFD)-fed mice, 28-day oral treatment with PCN aggravated diet-induced liver steatosis while atorvastatin had no effect. 28-day atorvastatin treatment reduced the hepatic expression of PXR, and its effect on cholesterol synthesis genes disappeared. PCN did not influence PXR expression, and the Cyp3a11 expression remained induced still after 28 days. Among the lipogenic genes studied, Scd1 was the only one significantly induced by PCN after 28-day treatment in the HFD-fed mice. In summary, atorvastatin regulates mouse liver transcriptomics PXR dependently but differently from PCN and represses PXR in long-term treatment in the HFD-fed mice. Unlike PCN, atorvastatin does not promote liver steatosis.
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: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.