Project description:To identify the CAR-, PXR- and PPARα-specific genome-wide expression changes, hepatocyte cultures from six individual donors were treated with the prototypical ligands for CAR (CITCO), PXR (rifampicin) and PPARα (WY14,643) as well as DMSO (vehicle control). Afterwards, the mRNA expression in these samples was determined utilizing Affymetrix® microarrays. Primary human hepatocytes (PHH) from 6 donors were treated for 24 h with 10µM of rifampicin, 50µM of WY14,643, 1µM of CITCO and 0.1% of DMSO (vehicle).
Project description:To identify the CAR-, PXR- and PPARα-specific genome-wide expression changes, hepatocyte cultures from six individual donors were treated with the prototypical ligands for CAR (CITCO), PXR (rifampicin) and PPARα (WY14,643) as well as DMSO (vehicle control). Afterwards, the mRNA expression in these samples was determined utilizing Affymetrix® microarrays.
Project description:In primary human hepatocytes (PHH) the involvement of the Pregnane X Receptor (PXR) in genes regulations by Phenobarbital (PB) has never been evaluated at the transcriptomic level. Here we investigated the impact of PXR depletion and epidermal growth factor on PXR dependent gene modulation by PB in PHH. The potential crosstalk with CAR was investigated using Phenobarbital and the direct CAR activator (CITCO) in presence or in absence of EGF.
Project description:Background Genomic variations contribute to the phenotypic diversity of individuals. A number of polymorphisms in protein-coding regions that alter drug efficacy or lead to adverse reactions have been characterized; however, noncoding regions that affect drug responses are largely overlooked, except for a limited number of well-studied enhancers. Results We conducted a quantitative assessment of cis-regulatory elements (CREs) based on transcription initiation profiling of mRNAs and noncoding RNAs, including enhancer RNAs, by using CAGE (Cap Analysis of Gene Expression). Candidate CREs identified in a hepatocellular carcinoma HepG2 cell line with stable expression of drug-responsive transcription factor pregnane X receptor (PXR) were further narrowed down by integrating data of PXR-binding sites in human primary hepatocytes and genome-wide association studies. We found more than 100-fold enrichments of the candidates to genetically associated loci with circulating levels of bilirubin and vitamin D, which implicated a link to adverse reactions of PXR ligands. We uncovered novel enhancers of UGT1A1 and TSKU through CRISPR/Cas9 knockout experiments. We identified alleles altering regulatory activities of UGT1A1 and CYP24A1enhancers by using luciferase reporter assay. Furthermore, our siRNA experiments revealed an unexpected impact of TSKU on the expression of vitamin D-metabolizing enzymes. Conclusions Our transcriptome-based assessment of CREs expanded the list of drug-inducible and PXR-mediated enhancers and super-enhancers. We identified regulatory alleles that alter drug-induced gene expressions, and discovered a novel molecular cascade associated with an adverse reaction. Our results contribute a precise understanding of the noncoding elements of the human genome underlying drug responses.
Project description:Purpose: The goal of this study was to investigate how PBDEs regulate both PCGs and lncRNAs in a PXR/CAR ligand-dependent and independent manner Methods: HepaRG cells, which are human-derived hepatic cells that accurately represent gene expression profiles of human liver tissue, were exposed to BDE-47 and BDE-99 at a dose of 25 μM for 24 hours. Differentially expressed lncRNA-PCG pairs were identified through DESeq2 and HOMER; significant canonical pathways were determined through Ingenuity Pathway Analysis (IPA). LncTar was used to predict the binding of 19 lncRNA-PCG pairs with known roles in drug-processing pathways. Results: Genome annotation revealed that the majority of the differentially expressed lncRNAs map to PCG introns. PBDEs regulated overlapping pathways with PXR and CAR such as protein ubiqutination pathway and peroxisome proliferator-activated receptor alpha-retinoid X receptor alpha (PPARα-RXRα) activation but also regulate distinctive pathways involved in intermediary metabolism. PBDEs uniquely down-regulated GDP-L-fucose biosynthesis, suggesting its role in modifying important pathways involved in intermediary metabolism such as carbohydrate and lipid metabolism. Conclusion: There is strong evidence that PBDEs regulate both PCGs and lncRNAs in a PXR/CAR ligand-dependent and independent manner
Project description:Viruses lack the basic machinery needed to replicate and therefore must hijack host metabolism to propagate. Virus-induced metabolic alterations have yet to be systematically studied in the context of the host transcriptional regulation, offering insight into host-pathogen metabolic interplay. In this work we identified Hepatitis C Virus (HCV)-responsive regulators by coupling system-wide metabolic flux analysis with targeted perturbation of nuclear receptors in primary human hepatocytes. We find HCV-induced up-regulation of glycolysis, ketogenesis and drug metabolism, controlled by activation of HNF4α, PPARα, FXR and PXR, respectively. Pharmaceutical inhibition of HNF4α reversed HCV-induced glycolysis, blocking viral replication while increasing apoptosis in infected cells showing a viral-induced dependence on glycolysis. In contrast, pharmaceutical inhibition of PPARα or FXR reversed HCV-induced ketogenesis, but increased viral replication demonstrating a unique host anti-viral response. Our results show that viral-induced changes to host metabolism can be detrimental to its lifecycle demonstrating a distinct biological complexity. In this dataset, we include the expression data obtained from primary human hepatocyte oxygenated co-cultures infected or not infected by HCV and human sanp frozen liver biopsys from HCV patients at earley stages.
Project description:The nuclear receptors CAR (constitutive androstane receptor) and PXR (pregnane X receptor) mediate the effects of phenobarbital (PB) on gene transcription. To investigate the relative role of CAR and PXR in the induction response, cDNA arrays were generated containing 120 genes which are known to be regulated with these or related nuclear receptors (genes involved in drug metabolism, cholesterol biosynthesis, sterol synthesis/transport, heme synthesis). Samples from livers of wild type and CAR-/-, PXR-/- or CAR/PXR-/- knockout mice were tested after treatment with PB for gene expression within the European Framework V program “Steroltalk” (www.steroltalk.net). Results from these experiments unexpectedly revealed that if CAR and PXR are deleted, PB increases the expression of several other nuclear receptors and genes involved in drug metabolism and cholesterol biosynthesis. Animals were injected i.p. 100mg/kg phenobarbital or vehicle (5% DMSO in corn oil). After 12h they were sacrificed and total RNA was isolated from the livers. Pools of untreated samples were mixed in each genetic variant group (wild type and CAR-/-, PXR-/- or CAR/PXR-/-) with the phenobarbital treated ones and hybridized to Sterolgene V1 arrays.
Project description:The nuclear receptor PXR (Pregnane X rreceptor) mediates the effects of pregnenolone-16alpha-carbonitrile (PCN) on gene transcription. The relative role of PXR and also CAR to the induction response by PCN was studied on cDNA arrays containing 320 (Steroltalk V2) genes (genes involved in cyrcadian rhythm, drug metabolism, cholesterol biosynthesis, sterol synthesis/transport, heme synthesis). Samples from livers of wild type and CAR-/-, PXR-/- or CAR/PXR-/- knockout mice were tested after treatment with PCN for gene expression within the European Framework V program âSteroltalkâ (www.steroltalk.net). Results from these experiments show the complex role of PXR receptor in the expression of genes involved in cyrcadian rhythm, drug metabolism and cholesterol biosynthesis. Animals were injected i.p. 40mg/kg PCN or vehicle (5% DMSO in corn oil). After 12h they were sacrificed and total RNA was isolated from the livers. Pools of untreated samples were mixed in each genetic variant group (wild type and CAR-/-, PXR-/- or CAR/PXR-/-) with the PCN treated ones and hybridized to Steroltalk V2 arrays.
Project description:Background: Studies in mice have shown that PPARα is an important regulator of lipid metabolism in liver and a key transcription factor involved in the adaptive response to fasting. However, much less is known about the role of PPARα in human liver. Here we set out to study the function of PPARα in human liver via analysis of whole genome gene regulation in human liver slices treated with the PPARα agonist Wy14643. Results: Quantitative PCR indicated that PPARα is well expressed in human liver and human liver slices and that the classical PPARα targets PLIN2, VLDLR, ANGPTL4, CPT1A and PDK4 are robustly induced by PPARα activation. Transcriptomics analysis indicated that 617 genes were upregulated and 665 genes were downregulated by PPARα activation (q value<0.05). Many genes induced by PPARα activation were involved in lipid metabolism (ACSL5, AGPAT9, FADS1, SLC27A4), xenobiotic metabolism (POR, ABCC2, CYP3A5) or the unfolded protein response, whereas most of the downregulated genes were involved in immune-related pathways. Among the most highly repressed genes upon PPARα activation were several chemokines (e.g. CXCL9-11, CCL8, CX3CL1, CXCL6), interferon γ-induced genes (e.g. IFITM1, IFIT1, IFIT2, IFIT3) and numerous other immune-related genes (e.g. TLR3, NOS2, and LCN2). Comparative analysis of gene regulation by Wy14643 between human liver slices and primary human hepatocytes showed that down-regulation of gene expression by PPARα is much better captured by liver slices as compared to primary hepatocytes. In particular, PPARα activation markedly suppressed immunity/inflammation-related genes in human liver slices but not in primary hepatocytes. Finally, several putative new target genes of PPARα were identified that were commonly induced by PPARα activation in the two human liver model systems, including TSKU, RHOF, CA12 and VSIG10L. Conclusion: Our manuscript demonstrates the suitability and superiority of human liver slices over primary hepatocytes for studying the functional role of PPARα in human liver. Our data underscore the major role of PPARα in regulation of hepatic lipid and xenobiotic metabolism in human liver and reveal a marked immuno-suppressive/anti-inflammatory effect of PPARα in human liver slices that may be therapeutically relevant for non-alcoholic fatty liver disease.
Project description:The nuclear receptor CAR (constitutive androstane receptor) mediates the effects of 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) on gene transcription. To investigate the relative role of CAR and also PXR in the induction response, cDNA arrays were generated containing 120 (Sterolgene V1) genes which are known to be regulated with these or related nuclear receptors (genes involved in drug metabolism, cholesterol biosynthesis, sterol synthesis/transport, heme synthesis). Samples from livers of wild type and CAR-/-, PXR-/- or CAR/PXR-/- knockout mice were tested after treatment with TCPOBOP for gene expression within the European Framework V program “Steroltalk” (www.steroltalk.net). Results from these experiments show the complex role of CAR receptor in the expression of genes involved in drug metabolism and cholesterol biosynthesis. Animals were injected i.p. 10mg/kg TCPOBOP or vehicle (5% DMSO in corn oil). After 12h they were sacrificed and total RNA was isolated from the livers. Pools of untreated samples were mixed in each genetic variant group (wild type and CAR-/-, PXR-/- or CAR/PXR-/-) with the TCPOBOP treated ones and hybridized to Sterolgene V1 arrays.