1
|
UPLC-MS/MS assay for the simultaneous determination of catecholamines and their metabolites at low pg/mg in rat/mouse striatum. J Pharm Biomed Anal 2022; 213:114697. [DOI: 10.1016/j.jpba.2022.114697] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 02/17/2022] [Accepted: 02/26/2022] [Indexed: 12/23/2022]
|
2
|
Niu X, Wu T, Li G, Gu X, Tian Y, Cui H. Insights into the critical role of the PXR in preventing carcinogenesis and chemotherapeutic drug resistance. Int J Biol Sci 2022; 18:742-759. [PMID: 35002522 PMCID: PMC8741843 DOI: 10.7150/ijbs.68724] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 11/21/2021] [Indexed: 12/12/2022] Open
Abstract
Pregnane x receptor (PXR) as a nuclear receptor is well-established in drug metabolism, however, it has pleiotropic functions in regulating inflammatory responses, glucose metabolism, and protects normal cells against carcinogenesis. Most studies focus on its transcriptional regulation, however, PXR can regulate gene expression at the translational level. Emerging evidences have shown that PXR has a broad protein-protein interaction network, by which is implicated in the cross signaling pathways. Furthermore, the interactions between PXR and some critical proteins (e.g., p53, Tip60, p300/CBP-associated factor) in DNA damage pathway highlight its potential roles in this field. A thorough understanding of how PXR maintains genome stability and prevents carcinogenesis will help clinical diagnosis and finally benefit patients. Meanwhile, due to the regulation of CYP450 enzymes CYP3A4 and multidrug resistance protein 1 (MDR1), PXR contributes to chemotherapeutic drug resistance. It is worthy of note that the co-factor of PXR such as RXRα, also has contributions to this process, which makes the PXR-mediated drug resistance more complicated. Although single nucleotide polymorphisms (SNPs) vary between individuals, the amino acid substitution on exon of PXR finally affects PXR transcriptional activity. In this review, we have summarized the updated mechanisms that PXR protects the human body against carcinogenesis, and major contributions of PXR with its co-factors have made on multidrug resistance. Furthermore, we have also reviewed the current promising antagonist and their clinic applications in reversing chemoresistance. We believe our review will bring insight into PXR-targeted cancer therapy, enlighten the future study direction, and provide substantial evidence for the clinic in future.
Collapse
Affiliation(s)
- Xiaxia Niu
- Institute of Toxicology, School of Public Health, Lanzhou University, 730000, Lanzhou, China
| | - Ting Wu
- Institute of Toxicology, School of Public Health, Lanzhou University, 730000, Lanzhou, China
| | - Gege Li
- Institute of Toxicology, School of Public Health, Lanzhou University, 730000, Lanzhou, China
| | - Xinsheng Gu
- Department of Pharmacology, College of Basic Medical Sciences, Hubei University of Medicine, Shiyan 442000, Hubei, China
| | - Yanan Tian
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, USA
| | - Hongmei Cui
- Institute of Toxicology, School of Public Health, Lanzhou University, 730000, Lanzhou, China
| |
Collapse
|
3
|
Discrepancy in interactions and conformational dynamics of pregnane X receptor (PXR) bound to an agonist and a novel competitive antagonist. Comput Struct Biotechnol J 2022; 20:3004-3018. [PMID: 35782743 PMCID: PMC9218138 DOI: 10.1016/j.csbj.2022.06.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 06/09/2022] [Accepted: 06/09/2022] [Indexed: 11/22/2022] Open
|
4
|
Rogers RS, Parker A, Vainer PD, Elliott E, Sudbeck D, Parimi K, Peddada VP, Howe PG, D’Ambrosio N, Ruddy G, Stackable K, Carney M, Martin L, Osterholt T, Staudinger JL. The Interface between Cell Signaling Pathways and Pregnane X Receptor. Cells 2021; 10:cells10113262. [PMID: 34831484 PMCID: PMC8617909 DOI: 10.3390/cells10113262] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/19/2022] Open
Abstract
Highly expressed in the enterohepatic system, pregnane X receptor (PXR, NR1I2) is a well-characterized nuclear receptor (NR) that regulates the expression of genes in the liver and intestines that encode key drug metabolizing enzymes and drug transporter proteins in mammals. The net effect of PXR activation is to increase metabolism and clear drugs and xenobiotics from the body, producing a protective effect and mediating clinically significant drug interaction in patients on combination therapy. The complete understanding of PXR biology is thus important for the development of safe and effective therapeutic strategies. Furthermore, PXR activation is now known to specifically transrepress the inflammatory- and nutrient-signaling pathways of gene expression, thereby providing a mechanism for linking these signaling pathways together with enzymatic drug biotransformation pathways in the liver and intestines. Recent research efforts highlight numerous post-translational modifications (PTMs) which significantly influence the biological function of PXR. However, this thrust of research is still in its infancy. In the context of gene-environment interactions, we present a review of the recent literature that implicates PXR PTMs in regulating its clinically relevant biology. We also provide a discussion of how these PTMs likely interface with each other to respond to extracellular cues to appropriately modify PXR activity.
Collapse
Affiliation(s)
- Robert S. Rogers
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Annemarie Parker
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Phill D. Vainer
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Elijah Elliott
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Dakota Sudbeck
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Kaushal Parimi
- Thomas Jefferson Independent Day School, Joplin, MO 64801, USA;
| | - Venkata P. Peddada
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Parker G. Howe
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Nick D’Ambrosio
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Gregory Ruddy
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Kaitlin Stackable
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Megan Carney
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Lauren Martin
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Thomas Osterholt
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
| | - Jeff L. Staudinger
- Division of Basic Sciences, Farber-McIntire Campus, College of Osteopathic Medicine, Kansas City University, Joplin, MO 64804, USA; (R.S.R.); (A.P.); (P.D.V.); (E.E.); (D.S.); (V.P.P.); (P.G.H.); (G.R.); (K.S.); (M.C.); (L.M.); (T.O.)
- Correspondence:
| |
Collapse
|
5
|
Rigalli JP, Theile D, Nilles J, Weiss J. Regulation of PXR Function by Coactivator and Corepressor Proteins: Ligand Binding Is Just the Beginning. Cells 2021; 10:cells10113137. [PMID: 34831358 PMCID: PMC8625645 DOI: 10.3390/cells10113137] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 12/13/2022] Open
Abstract
The pregnane X receptor (PXR, NR1I2) is a nuclear receptor which exerts its regulatory function by heterodimerization with the retinoid-X-receptor α (RXRα, NR2B1) and binding to the promoter and enhancer regions of diverse target genes. PXR is involved in the regulation of drug metabolism and excretion, metabolic and immunological functions and cancer pathogenesis. PXR activity is strongly regulated by the association with coactivator and corepressor proteins. Coactivator proteins exhibit histone acetyltransferase or histone methyltransferase activity or associate with proteins having one of these activities, thus promoting chromatin decondensation and activation of the gene expression. On the contrary, corepressor proteins promote histone deacetylation and therefore favor chromatin condensation and repression of the gene expression. Several studies pointed to clear cell- and ligand-specific differences in the activation of PXR. In this article, we will review the critical role of coactivator and corepressor proteins as molecular determinants of the specificity of PXR-mediated effects. As already known for other nuclear receptors, understanding the complex mechanism of PXR activation in each cell type and under particular physiological and pathophysiological conditions may lead to the development of selective modulators with therapeutic potential.
Collapse
|
6
|
Hall A, Chanteux H, Ménochet K, Ledecq M, Schulze MSED. Designing Out PXR Activity on Drug Discovery Projects: A Review of Structure-Based Methods, Empirical and Computational Approaches. J Med Chem 2021; 64:6413-6522. [PMID: 34003642 DOI: 10.1021/acs.jmedchem.0c02245] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This perspective discusses the role of pregnane xenobiotic receptor (PXR) in drug discovery and the impact of its activation on CYP3A4 induction. The use of structural biology to reduce PXR activity on drug discovery projects has become more common in recent years. Analysis of this work highlights several important molecular interactions, and the resultant structural modifications to reduce PXR activity are summarized. The computational approaches undertaken to support the design of new drugs devoid of PXR activation potential are also discussed. Finally, the SAR of empirical design strategies to reduce PXR activity is reviewed, and the key SAR transformations are discussed and summarized. In conclusion, this perspective demonstrates that PXR activity can be greatly diminished or negated on active drug discovery projects with the knowledge now available. This perspective should be useful to anyone who seeks to reduce PXR activity on a drug discovery project.
Collapse
Affiliation(s)
- Adrian Hall
- UCB, Avenue de l'Industrie, Braine-L'Alleud 1420, Belgium
| | | | | | - Marie Ledecq
- UCB, Avenue de l'Industrie, Braine-L'Alleud 1420, Belgium
| | | |
Collapse
|
7
|
Cui W, Shen X, Agbas E, Tompkins B, Cameron-Carter H, Staudinger JL. Phosphorylation Modulates the Coregulatory Protein Exchange of the Nuclear Receptor Pregnane X Receptor. J Pharmacol Exp Ther 2020; 373:370-380. [PMID: 32205367 DOI: 10.1124/jpet.119.264762] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 03/10/2020] [Indexed: 01/09/2023] Open
Abstract
The pregnane X receptor (PXR), or nuclear receptor (NR) 1I2, is a ligand-activated NR superfamily member that is enriched in liver and intestine in mammals. Activation of PXR regulates the expression of genes encoding key proteins involved in drug metabolism, drug efflux, and drug transport. Recent mechanistic investigations reveal that post-translational modifications (PTMs), such as phosphorylation, play a critical role in modulating the bimodal function of PXR-mediated transrepression and transactivation of target gene transcription. Upon ligand binding, PXR undergoes a conformational change that promotes dissociation of histone deacetylase-containing multiprotein corepressor protein complexes while simultaneously favoring recruitment histone acetyl transferase-containing complexes. Here we describe a novel adenoviral vector used to deliver and recover recombinant human PXR protein from primary cultures of hepatocytes. Using liquid chromatography and tandem mass spectrometry we report here that PXR is phosphorylated at amino acid residues threonine 135 (T135) and serine 221 (S221). Biochemical analysis reveals that these two residues play an important regulatory role in the cycling of corepressor and coactivator multiprotein complexes. These data further our foundational knowledge regarding the specific role of PTMs, namely phosphorylation, in regulating the biology of PXR. Future efforts are focused on using the novel tools described here to identify additional PTMs and protein partners of PXR in primary cultures of hepatocytes, an important experimental model system. SIGNIFICANCE STATEMENT: Pregnane X receptor (PXR), or nuclear receptor 1I2, is a key master regulator of drug-inducible CYP gene expression in liver and intestine in mammals. The novel biochemical tools described in this study demonstrate for the first time that in cultures of primary hepatocytes, human PXR is phosphorylated at amino acid residues threonine 135 (T135) and serine 221 (S221). Moreover, phosphorylation of PXR promotes the transrepression of its prototypical target gene CYP3A4 through modulating its interactions with coregulatory proteins.
Collapse
Affiliation(s)
- Wenqi Cui
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (W.C.); Stowers Institute for Medical Research, Kansas City, Missouri (E.A.); Department of Bioinformatics, University of Georgia, Ethan, Georgia (X.S.); and Kansas City University of Medicine and Biosciences, Joplin, Missouri (B.T., H.C.-C., J.L.S.)
| | - Xunan Shen
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (W.C.); Stowers Institute for Medical Research, Kansas City, Missouri (E.A.); Department of Bioinformatics, University of Georgia, Ethan, Georgia (X.S.); and Kansas City University of Medicine and Biosciences, Joplin, Missouri (B.T., H.C.-C., J.L.S.)
| | - Emre Agbas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (W.C.); Stowers Institute for Medical Research, Kansas City, Missouri (E.A.); Department of Bioinformatics, University of Georgia, Ethan, Georgia (X.S.); and Kansas City University of Medicine and Biosciences, Joplin, Missouri (B.T., H.C.-C., J.L.S.)
| | - Brandon Tompkins
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (W.C.); Stowers Institute for Medical Research, Kansas City, Missouri (E.A.); Department of Bioinformatics, University of Georgia, Ethan, Georgia (X.S.); and Kansas City University of Medicine and Biosciences, Joplin, Missouri (B.T., H.C.-C., J.L.S.)
| | - Hadley Cameron-Carter
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (W.C.); Stowers Institute for Medical Research, Kansas City, Missouri (E.A.); Department of Bioinformatics, University of Georgia, Ethan, Georgia (X.S.); and Kansas City University of Medicine and Biosciences, Joplin, Missouri (B.T., H.C.-C., J.L.S.)
| | - Jeff L Staudinger
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota (W.C.); Stowers Institute for Medical Research, Kansas City, Missouri (E.A.); Department of Bioinformatics, University of Georgia, Ethan, Georgia (X.S.); and Kansas City University of Medicine and Biosciences, Joplin, Missouri (B.T., H.C.-C., J.L.S.)
| |
Collapse
|
8
|
Carazo A, Mladěnka P, Pávek P. Marine Ligands of the Pregnane X Receptor (PXR): An Overview. Mar Drugs 2019; 17:md17100554. [PMID: 31569349 PMCID: PMC6836225 DOI: 10.3390/md17100554] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 09/27/2019] [Accepted: 09/27/2019] [Indexed: 02/06/2023] Open
Abstract
Pregnane X Receptor (PXR) is a ligand-activated transcription factor which binds many structurally different molecules. The receptor is able to regulate the expression of a wide array of genes and is involved in cancer and different key physiological processes such as the metabolism of drugs/xenobiotics and endogenous compounds including lipids and carbohydrates, and inflammation. Algae, sponges, sea squirts, and other marine organisms are some of the species from which structurally new molecules have been isolated that have been subsequently identified in recent decades as ligands for PXR. The therapeutic potential of these natural compounds is promising in different areas and has recently resulted in the registration of trabectedin by the FDA as a novel antineoplastic drug. Apart from being potentially novel drugs, these compounds can also serve as models for the development of new molecules with improved activity. The aim of this review is to succinctly summarize the currently known natural molecules isolated from marine organisms with a proven ability to interact with PXR.
Collapse
Affiliation(s)
- Alejandro Carazo
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovského 1203, Hradec Králové 500 05, Czech Republic.
| | - Přemysl Mladěnka
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovského 1203, Hradec Králové 500 05, Czech Republic.
| | - Petr Pávek
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovského 1203, Hradec Králové 500 05, Czech Republic.
| |
Collapse
|
9
|
Rigalli JP, Tocchetti GN, Weiss J. Modulation of ABC Transporters by Nuclear Receptors: Physiological, Pathological and Pharmacological Aspects. Curr Med Chem 2019; 26:1079-1112. [DOI: 10.2174/0929867324666170920141707] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/24/2017] [Accepted: 08/08/2017] [Indexed: 12/11/2022]
Abstract
ABC transporters are membrane proteins mediating the efflux of endo- and xenobiotics. Transporter expression is not static but instead is subject to a dynamic modulation aiming at responding to changes in the internal environment and thus at maintaining homeostatic conditions. Nuclear receptors are ligand modulated transcription factors that get activated upon changes in the intracellular concentrations of the respective agonists and bind to response elements within the promoter of ABC transporters, thus modulating their expression and, consequently, their activity. This review compiles information about transporter regulation by nuclear receptors classified according to the perpetrator compounds and the biological effects resulting from the regulation. Modulation by hormone receptors is involved in maintaining endocrine homeostasis and may also lead to an altered efflux of other substrates in cases of altered hormonal levels. Xenobiotic receptors play a key role in limiting the accumulation of potentially harmful compounds. In addition, their frequent activation by therapeutic agents makes them common molecular elements mediating drug-drug interactions and cancer multidrug resistance. Finally, lipid and retinoid receptors are usually activated by endogenous molecules, thus sensing metabolic changes and inducing ABC transporters to counteract potential alterations. Furthermore, the axis nuclear receptor-ABC transporter constitutes a promising therapeutic target for the treatment of several disease states like cancer, atherosclerosis and dyslipidemia. In the current work, we summarize the information available on the pharmacological potential of nuclear receptor modulators and discuss their applicability in the clinical practice.
Collapse
Affiliation(s)
- Juan Pablo Rigalli
- Department of Clinical Pharmacology and Pharmacoepidemiology. University of Heidelberg. Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Guillermo Nicolás Tocchetti
- Department of Clinical Pharmacology and Pharmacoepidemiology. University of Heidelberg. Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Johanna Weiss
- Department of Clinical Pharmacology and Pharmacoepidemiology. University of Heidelberg. Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| |
Collapse
|
10
|
Dempsey JL, Cui JY. Regulation of Hepatic Long Noncoding RNAs by Pregnane X Receptor and Constitutive Androstane Receptor Agonists in Mouse Liver. Drug Metab Dispos 2019; 47:329-339. [PMID: 30593543 PMCID: PMC6382996 DOI: 10.1124/dmd.118.085142] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 12/21/2018] [Indexed: 12/28/2022] Open
Abstract
Altered expression of long noncoding RNAs (lncRNAs) by environmental chemicals modulates the expression of xenobiotic biotransformation-related genes and may serve as therapeutic targets and novel biomarkers of exposure. The pregnane X receptor (PXR/NR1I2) is a critical xenobiotic-sensing nuclear receptor that regulates the expression of many drug-processing genes, and it has similar target-gene profiles and DNA-binding motifs with another xenobiotic-sensing nuclear receptor, namely, constitutive andronstrane receptor (CAR/Nr1i3). To test our hypothesis that lncRNAs are regulated by PXR in concert with protein-coding genes (PCGs) and to compare the PXR-targeted lncRNAs with CAR-targeted lncRNAs, RNA-Seq was performed from livers of adult male C57BL/6 mice treated with corn oil, the PXR agonist PCN, or the CAR agonist 1, 4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP). Among 125,680 known lncRNAs, 3843 were expressed in liver, and 193 were differentially regulated by PXR (among which 40% were also regulated by CAR). Most PXR- or CAR-regulated lncRNAs were mapped to the introns and 3'-untranslated regions (UTRs) of PCGs, as well as intergenic regions. Combining the RNA-Seq data with a published PXR chromatin immunoprecipitation coupled with high-throughput sequencing; cytochrome P450 (P450; ChIP-Seq) data set, we identified 774 expressed lncRNAs with direct PXR-DNA binding sites, and 26.8% of differentially expressed lncRNAs had changes in PXR-DNA binding after PCN exposure. De novo motif analysis identified colocalization of PXR with liver receptor homolog (LRH-1), which regulates bile acid synthesis after PCN exposure. There was limited overlap of PXR binding with an epigenetic mark for transcriptional activation (histone-H3K4-di-methylation, H3K4me2) but no overlap with epigenetic marks for transcriptional silencing [H3 lysine 27 tri-methylation (H3K27me3) and DNA methylation]. Among differentially expressed lncRNAs, 264 were in proximity of PCGs, and the lncRNA-PCG pairs displayed a high coregulatory pattern by PXR and CAR activation. This study was among the first to demonstrate that lncRNAs are regulated by PXR and CAR activation and that they may be important regulators of PCGs involved in xenobiotic metabolism.
Collapse
Affiliation(s)
- Joseph L Dempsey
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington
| | - Julia Yue Cui
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington
| |
Collapse
|
11
|
Tebbens JD, Azar M, Friedmann E, Lanzendörfer M, Pávek P. Mathematical Models in the Description of Pregnane X Receptor (PXR)-Regulated Cytochrome P450 Enzyme Induction. Int J Mol Sci 2018; 19:ijms19061785. [PMID: 29914136 PMCID: PMC6032247 DOI: 10.3390/ijms19061785] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 06/13/2018] [Accepted: 06/13/2018] [Indexed: 02/06/2023] Open
Abstract
The pregnane X receptor (PXR) is a drug/xenobiotic-activated transcription factor of crucial importance for major cytochrome P450 xenobiotic-metabolizing enzymes (CYP) expression and regulation in the liver and the intestine. One of the major target genes regulated by PXR is the cytochrome P450 enzyme (CYP3A4), which is the most important human drug-metabolizing enzyme. In addition, PXR is supposed to be involved both in basal and/or inducible expression of many other CYPs, such as CYP2B6, CYP2C8, 2C9 and 2C19, CYP3A5, CYP3A7, and CYP2A6. Interestingly, the dynamics of PXR-mediated target genes regulation has not been systematically studied and we have only a few mechanistic mathematical and biologically based models describing gene expression dynamics after PXR activation in cellular models. Furthermore, few indirect mathematical PKPD models for prediction of CYP3A metabolic activity in vivo have been built based on compartmental models with respect to drug–drug interactions or hormonal crosstalk. Importantly, several negative feedback loops have been described in PXR regulation. Although current mathematical models propose these adaptive mechanisms, a comprehensive mathematical model based on sufficient experimental data is still missing. In the current review, we summarize and compare these models and address some issues that should be considered for the improvement of PXR-mediated gene regulation modelling as well as for our better understanding of the quantitative and spatial dynamics of CYPs expression.
Collapse
Affiliation(s)
- Jurjen Duintjer Tebbens
- Department of Biophysics and Physical Chemistry, Faculty of Pharmacy, Charles University, Heyrovského 1203, 500 05 Hradec Kralove, Czech Republic.
| | - Malek Azar
- Department of Biophysics and Physical Chemistry, Faculty of Pharmacy, Charles University, Heyrovského 1203, 500 05 Hradec Kralove, Czech Republic.
| | - Elfriede Friedmann
- Department of Applied Mathematics, Faculty of Mathematics and Computer Sciences, Mathematikon, University Heidelberg, Im Neuenheimer Feld 205, D-69120 Heidelberg, Germany.
| | - Martin Lanzendörfer
- Institute of Hydrogeology, Engineering Geology and Applied Geophysics, Faculty of Science, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic.
| | - Petr Pávek
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovského 1203, 500 05 Hradec Kralove, Czech Republic.
| |
Collapse
|
12
|
Rigalli JP, Reichel M, Reuter T, Tocchetti GN, Dyckhoff G, Herold-Mende C, Theile D, Weiss J. The pregnane X receptor (PXR) and the nuclear receptor corepressor 2 (NCoR2) modulate cell growth in head and neck squamous cell carcinoma. PLoS One 2018; 13:e0193242. [PMID: 29470550 PMCID: PMC5823449 DOI: 10.1371/journal.pone.0193242] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 02/07/2018] [Indexed: 01/19/2023] Open
Abstract
Head and neck squamous cell carcinoma (HNSCC) is the sixth most frequent cancer worldwide. The pregnane X receptor (PXR) is a nuclear receptor regulating several target genes associated with cancer malignancy. We here demonstrated a significant effect of PXR on HNSCC cell growth, as evidenced in PXR knock-down experiments. PXR transcriptional activity is more importantly regulated by the presence of coactivators and corepressors than by PXR protein expression. To date, there is scarce information on the regulation of PXR in HNSCC and on its role in the pathogenesis of this disease. Coactivator and corepressor expression was screened through qRT-PCR in 8 HNSCC cell lines and correlated to PXR activity, determined by using a reporter gene assay. All cell lines considerably expressed all the cofactors assessed. PXR activity negatively correlated with nuclear receptor corepressor 2 (NCoR2) expression, indicating a major role of this corepressor in PXR modulation and suggesting its potential as a surrogate for PXR activity in HNSCC. To test the association of NCoR2 with the malignant phenotype, a subset of three cell lines was transfected with an over-expression plasmid for this corepressor. Subsequently, cell growth and chemoresistance assays were performed. To elucidate the mechanisms underlying NCoR2 effects on cell growth, caspase 3/7 activity and protein levels of cleaved caspase 3 and PARP were evaluated. In HNO97 cells, NCoR2 over-expression decreased cell growth, chemoresistance and increased cleaved caspase 3 levels, caspase activity and cleaved PARP levels. On the contrary, in HNO124 and HNO210 cells, NCoR2 over-expression increased cell growth, drug resistance and decreased cleaved caspase 3 levels, caspase activity and cleaved PARP levels. In conclusion, we demonstrated a role of PXR and NCoR2 in the modulation of cell growth in HNSCC. This may contribute to a better understanding of the highly variable HNSCC therapeutic response.
Collapse
Affiliation(s)
- Juan Pablo Rigalli
- Department of Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany
| | - Matthias Reichel
- Department of Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany
| | - Tasmin Reuter
- Department of Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany
| | - Guillermo Nicolás Tocchetti
- Department of Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany
- Institute of Experimental Physiology (IFISE-CONICET), Rosario, Argentina
| | - Gerhard Dyckhoff
- Molecular Cell Biology Group, Department of Otorhinolaryngology, Head and Neck Surgery, University of Heidelberg, Heidelberg, Germany
| | - Christel Herold-Mende
- Molecular Cell Biology Group, Department of Otorhinolaryngology, Head and Neck Surgery, University of Heidelberg, Heidelberg, Germany
- Division of Neurosurgical Research, Department of Neurosurgery, University of Heidelberg, Heidelberg, Germany
| | - Dirk Theile
- Department of Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany
| | - Johanna Weiss
- Department of Clinical Pharmacology and Pharmacoepidemiology, University of Heidelberg, Heidelberg, Germany
- * E-mail:
| |
Collapse
|
13
|
Yokobori K, Kobayashi K, Azuma I, Akita H, Chiba K. Intracellular localization of pregnane X receptor in HepG2 cells cultured by the hanging drop method. Drug Metab Pharmacokinet 2017; 32:265-272. [DOI: 10.1016/j.dmpk.2017.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Revised: 08/05/2017] [Accepted: 08/17/2017] [Indexed: 11/25/2022]
|
14
|
He L, Zhou X, Huang N, Li H, Li T, Yao K, Tian Y, Hu CAA, Yin Y. Functions of pregnane X receptor in self-detoxification. Amino Acids 2017; 49:1999-2007. [PMID: 28534176 DOI: 10.1007/s00726-017-2435-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 05/03/2017] [Indexed: 12/19/2022]
Abstract
Pregnane X receptor (PXR, NR1I2), a member of the nuclear receptor superfamily, is a crucial regulator of nutrient metabolism and metabolic detoxification such as metabolic syndrome, xenobiotic metabolism, inflammatory responses, glucose, cholesterol and lipid metabolism, and endocrine homeostasis. Notably, much experimental and clinical evidence show that PXR senses xenobiotics and triggers the detoxification response to prevent diseases such as diabetes, obesity, intestinal inflammatory diseases and liver fibrosis. In this review we summarize recent advances on remarkable metabolic and regulatory versatility of PXR, and we emphasizes its role and potential implication as an effective modulator of self-detoxification in animals and humans.
Collapse
Affiliation(s)
- Liuqin He
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock and Poultry, Changsha, 410125, Hunan, China.,University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - Xihong Zhou
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock and Poultry, Changsha, 410125, Hunan, China
| | - Niu Huang
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, 410128, Hunan, China
| | - Huan Li
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, 410128, Hunan, China
| | - Tiejun Li
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock and Poultry, Changsha, 410125, Hunan, China.,Hunan Co-Innovation Center of Animal Production Safety, Changsha, 410128, Hunan, China
| | - Kang Yao
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock and Poultry, Changsha, 410125, Hunan, China. .,College of Animal Science and Technology, Hunan Agricultural University, Changsha, 410128, Hunan, China. .,Hunan Co-Innovation Center of Animal Production Safety, Changsha, 410128, Hunan, China.
| | - Yanan Tian
- College of Animal Science and Technology, Hunan Agricultural University, Changsha, 410128, Hunan, China.,Department of Veterinary Physiology and Pharmacology, Texas A & M University, College Station, TX, 77843, USA
| | - Chien-An Andy Hu
- Department of Biochemistry and Molecular Biology, University of New Mexico, Health Sciences Center, MSC08 4670, Albuquerque, USA
| | - Yulong Yin
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Hunan Provincial Engineering Research Center of Healthy Livestock and Poultry, Changsha, 410125, Hunan, China. .,Hunan Co-Innovation Center of Animal Production Safety, Changsha, 410128, Hunan, China.
| |
Collapse
|
15
|
Kim SW, Md Hasanuzzaman, Cho M, Kim NH, Choi HY, Han JW, Park HJ, Oh JW, Shin JG. Role of 14-3-3 sigma in over-expression of P-gp by rifampin and paclitaxel stimulation through interaction with PXR. Cell Signal 2017; 31:124-134. [PMID: 28077325 DOI: 10.1016/j.cellsig.2017.01.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 01/01/2017] [Accepted: 01/03/2017] [Indexed: 01/04/2023]
Abstract
In this study, we presented the role of 14-3-3σ to activate CK2-Hsp90β-PXR-MDR1 pathway on rifampin and paclitaxel treated LS174T cells and in vivo LS174T cell-xenografted nude mouse model. Following several in vitro and in vivo experiments, rifampin and paclitaxel were found to be stimulated the CK2-Hsp90β-PXR-MDR1 pathway. Of the proteins in this pathway, Pregnane X receptor (PXR) is a representative transcription factor of multidrug resistance protein 1 (MDR1). We constructed FLAG-PXR-LS174T stable cell lines and discovered 22 proteins that interacted with PXR on rifampin treatment. Among them, Hsp90β and 14-3-3σ were isolated for further study. Both the proteins were found to be localized in cytoplasm on rifampin treatment by using confocal microscopy. On the other hand, PXR was found to be localized in nucleus after rifampin and paclitaxel treatment by using cell fractionation assay. In Western blot analysis, rifampin did not influence the expression of 14-3-3σ protein. Transient transfection of 14-3-3σ into LS174T cells induced overexpression of PXR; however, P-glycoprotein (P-gp) was not changed significantly. P-gp overexpression was induced only when 14-3-3σ transfected LS174T cells were treated with rifampin and paclitaxel, whereas 14-3-3σ inhibition by nonpeptidic inhibitor, BV02 and 14-3-3σ siRNA reduced rifampin induced PXR and P-gp expression. Cell survival rates were much higher at 14-3-3σ-LS174T stable cell lines than LS174T cells following paclitaxel and vincristine treatment. This data indicates that 14-3-3σ contributes to P-gp overexpression through interaction with PXR with rifampin and paclitaxel treatment.
Collapse
Affiliation(s)
- So Won Kim
- Department of Pharmacology, Catholic Kwandong University College of Medicine, Gangneung 25601, Republic of Korea; The Institute for Clinical and Translational Research, Catholic Kwandong University College of Medicine, Gangneung 25601, Republic of Korea.
| | - Md Hasanuzzaman
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 47392, Republic of Korea; Department of Pharmacy, Noakhali Science and Technology University, Sonapur, Noakhali 3814, Bangladesh
| | - Munju Cho
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 47392, Republic of Korea
| | - Nam Hyun Kim
- Department of Pharmacology, Catholic Kwandong University College of Medicine, Gangneung 25601, Republic of Korea
| | - Hye-Young Choi
- Department of Pharmacology, Catholic Kwandong University College of Medicine, Gangneung 25601, Republic of Korea
| | - Jung Woo Han
- Department of Pharmacology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Hyun June Park
- Department of Chemistry, University of Chicago, Chicago, IL 60637, USA
| | - Ji Won Oh
- Department of Anatomy, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea; Bio-Medical Research Institute, Kyungpook National University Hospital, Daegu 41944, Republic of Korea
| | - Jae-Gook Shin
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, Busan 47392, Republic of Korea; Department of Clinical Pharmacology, Inje University Busan Paik Hospital, Busan 47392, Republic of Korea.
| |
Collapse
|
16
|
Pavek P. Pregnane X Receptor (PXR)-Mediated Gene Repression and Cross-Talk of PXR with Other Nuclear Receptors via Coactivator Interactions. Front Pharmacol 2016; 7:456. [PMID: 27932985 PMCID: PMC5122737 DOI: 10.3389/fphar.2016.00456] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/14/2016] [Indexed: 12/13/2022] Open
Abstract
Pregnane X receptor is a ligand-activated nuclear receptor (NR) that mainly controls inducible expression of xenobiotics handling genes including biotransformation enzymes and drug transporters. Nowadays it is clear that PXR is also involved in regulation of intermediate metabolism through trans-activation and trans-repression of genes controlling glucose, lipid, cholesterol, bile acid, and bilirubin homeostasis. In these processes PXR cross-talks with other NRs. Accumulating evidence suggests that the cross-talk is often mediated by competing for common coactivators or by disruption of coactivation and activity of other transcription factors by the ligand-activated PXR. In this respect mainly PXR-CAR and PXR-HNF4α interference have been reported and several cytochrome P450 enzymes (such as CYP7A1 and CYP8B1), phase II enzymes (SULT1E1, Gsta2, Ugt1a1), drug and endobiotic transporters (OCT1, Mrp2, Mrp3, Oatp1a, and Oatp4) as well as intermediate metabolism enzymes (PEPCK1 and G6Pase) have been shown as down-regulated genes after PXR activation. In this review, I summarize our current knowledge of PXR-mediated repression and coactivation interference in PXR-controlled gene expression regulation.
Collapse
Affiliation(s)
- Petr Pavek
- Department of Pharmacology and Toxicology and Centre for Drug Development, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague Hradec Kralove, Czechia
| |
Collapse
|
17
|
Yang J, Zhu J, Chan KM. BDE-99, but not BDE-47, is a transient aryl hydrocarbon receptor agonist in zebrafish liver cells. Toxicol Appl Pharmacol 2016; 305:203-215. [DOI: 10.1016/j.taap.2016.06.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 06/19/2016] [Accepted: 06/20/2016] [Indexed: 12/17/2022]
|
18
|
Modulation of expression and activity of intestinal multidrug resistance-associated protein 2 by xenobiotics. Toxicol Appl Pharmacol 2016; 303:45-57. [DOI: 10.1016/j.taap.2016.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 04/29/2016] [Accepted: 05/01/2016] [Indexed: 12/24/2022]
|
19
|
Physiological and pathophysiological factors affecting the expression and activity of the drug transporter MRP2 in intestine. Impact on its function as membrane barrier. Pharmacol Res 2016; 109:32-44. [DOI: 10.1016/j.phrs.2016.04.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/15/2016] [Accepted: 04/17/2016] [Indexed: 12/15/2022]
|
20
|
Oladimeji P, Cui H, Zhang C, Chen T. Regulation of PXR and CAR by protein-protein interaction and signaling crosstalk. Expert Opin Drug Metab Toxicol 2016; 12:997-1010. [PMID: 27295009 DOI: 10.1080/17425255.2016.1201069] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Protein-protein interaction and signaling crosstalk contribute to the regulation of pregnane X receptor (PXR) and constitutive androstane receptor (CAR) and broaden their cellular function. AREA COVERED This review covers key historic discoveries and recent advances in our understanding of the broad function of PXR and CAR and their regulation by protein-protein interaction and signaling crosstalk. EXPERT OPINION PXR and CAR were first discovered as xenobiotic receptors; however, it is clear that PXR and CAR perform a much broader range of cellular functions through protein-protein interaction and signaling crosstalk, which typically mutually affect the function of all the partners involved. Future research on PXR and CAR should, therefore, look beyond their xenobiotic function.
Collapse
Affiliation(s)
- Peter Oladimeji
- a Department of Chemical Biology and Therapeutics , St. Jude Children's Research Hospital , Memphis , TN , USA
| | - Hongmei Cui
- a Department of Chemical Biology and Therapeutics , St. Jude Children's Research Hospital , Memphis , TN , USA
| | - Chen Zhang
- a Department of Chemical Biology and Therapeutics , St. Jude Children's Research Hospital , Memphis , TN , USA
| | - Taosheng Chen
- a Department of Chemical Biology and Therapeutics , St. Jude Children's Research Hospital , Memphis , TN , USA
| |
Collapse
|
21
|
Pondugula SR, Pavek P, Mani S. Pregnane X Receptor and Cancer: Context-Specificity is Key. NUCLEAR RECEPTOR RESEARCH 2016; 3. [PMID: 27617265 DOI: 10.11131/2016/101198] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pregnane X receptor (PXR) is an adopted orphan nuclear receptor that is activated by a wide-range of endobiotics and xenobiotics, including chemotherapy drugs. PXR plays a major role in the metabolism and clearance of xenobiotics and endobiotics in liver and intestine via induction of drug-metabolizing enzymes and drug-transporting proteins. However, PXR is expressed in several cancer tissues and the accumulating evidence strongly points to the differential role of PXR in cancer growth and progression as well as in chemotherapy outcome. In cancer cells, besides regulating the gene expression of enzymes and proteins involved in drug metabolism and transport, PXR also regulates other genes involved in proliferation, metastasis, apoptosis, anti-apoptosis, inflammation, and oxidative stress. In this review, we focus on the differential role of PXR in a variety of cancers, including prostate, breast, ovarian, endometrial, and colon. We also discuss the future directions to further understand the differential role of PXR in cancer, and conclude with the need to identify novel selective PXR modulators to target PXR in PXR-expressing cancers.
Collapse
Affiliation(s)
- Satyanarayana R Pondugula
- Department of Anatomy, Physiology and Pharmacology, Auburn University, Auburn, AL 36849, USA; Auburn University Research Initiative in Cancer, Auburn University, Auburn, AL 36849, USA
| | - Petr Pavek
- Faculty of Pharmacy in Hradec Králové, Charles University in Prague, Heyrovského 1203, Hradec Králové 500 05, Czech Republic, European Union
| | - Sridhar Mani
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, New York, NY 10461, USA
| |
Collapse
|
22
|
A SUMO-acetyl switch in PXR biology. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1170-1182. [PMID: 26883953 DOI: 10.1016/j.bbagrm.2016.02.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 01/22/2016] [Accepted: 02/09/2016] [Indexed: 12/13/2022]
Abstract
Post-translational modification (PTM) of nuclear receptor superfamily members regulates various aspects of their biology to include sub-cellular localization, the repertoire of protein-binding partners, as well as their stability and mode of degradation. The nuclear receptor pregnane X receptor (PXR, NR1I2) is a master-regulator of the drug-inducible gene expression in liver and intestine. The PXR-mediated gene activation program is primarily recognized to increase drug metabolism, drug transport, and drug efflux pathways in these tissues. The activation of PXR also has important implications in significant human diseases including inflammatory bowel disease and cancer. Our recent investigations reveal that PXR is modified by multiple PTMs to include phosphorylation, SUMOylation, and ubiquitination. Using both primary cultures of hepatocytes and cell-based assays, we show here that PXR is modified through acetylation on lysine residues. Further, we show that increased acetylation of PXR stimulates its increased SUMO-modification to support active transcriptional suppression. Pharmacologic inhibition of lysine de-acetylation using trichostatin A (TSA) alters the sub-cellular localization of PXR in cultured hepatocytes, and also has a profound impact upon PXR transactivation capacity. Both the acetylation and SUMOylation status of the PXR protein is affected by its ability to associate with the lysine de-acetylating enzyme histone de-acetylase (HDAC)3 in a complex with silencing mediator of retinoic acid and thyroid hormone receptor (SMRT). Taken together, our data support a model in which a SUMO-acetyl 'switch' occurs such that acetylation of PXR likely stimulates SUMO-modification of PXR to promote the active repression of PXR-target gene expression. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.
Collapse
|
23
|
Affiliation(s)
- Daniel D Bikle
- Departments of Medicine and Dermatology, VA Medical Center and University of California San Francisco, San Francisco, CA, USA
| |
Collapse
|
24
|
Ong SS, Goktug AN, Elias A, Wu J, Saunders D, Chen T. Stability of the human pregnane X receptor is regulated by E3 ligase UBR5 and serine/threonine kinase DYRK2. Biochem J 2014; 459:193-203. [PMID: 24438055 PMCID: PMC3959618 DOI: 10.1042/bj20130558] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The hPXR (human pregnane X receptor), a major chemical toxin sensor, is a ligand-induced transcription factor activated by various xenobiotics and toxins, resulting in the transcriptional up-regulation of detoxifying enzymes. To date, little is known about the upstream regulation of hPXR. Using MS analysis and a kinome-wide siRNA screen, we report that the E3 ligase UBR5 (ubiquitin protein ligase E3 component n-recognin 5) and DYRK2 (dual-specificity tyrosine-phosphorylation-regulated kinase 2) regulate hPXR stability. UBR5 knockdown resulted in accumulation of cellular hPXR and a concomitant increase in hPXR activity, whereas the rescue of UBR5 knockdown decreased the cellular hPXR level and activity. Importantly, UBR5 exerted its effect in concert with the serine/threonine kinase DYRK2, as the knockdown of DYRK2 phenocopied UBR5 knockdown. hPXR was shown to be a substrate for DYRK2, and DYRK2-dependent phosphorylation of hPXR facilitated its subsequent ubiquitination by UBR5. This is the first report of the post-translational regulation of hPXR via phosphorylation-facilitated ubiquitination by DYRK2 and UBR5. The results of the present study reveal the role of the ubiquitin-proteasomal pathway in modulating hPXR activity and indicate that pharmacological inhibitors of the ubiquitin-proteasomal pathway that regulate hPXR stability may negatively affect treatment outcome from unintended hPXR-mediated drug-drug interactions.
Collapse
Affiliation(s)
- Su Sien Ong
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee 38105, USA
| | - Asli N. Goktug
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee 38105, USA
| | - Ayesha Elias
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee 38105, USA
| | - Jing Wu
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee 38105, USA
| | - Darren Saunders
- Cancer Research Program, Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst NSW 2010, Australia
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee 38105, USA
| |
Collapse
|
25
|
Elias A, High AA, Mishra A, Ong SS, Wu J, Peng J, Chen T. Identification and characterization of phosphorylation sites within the pregnane X receptor protein. Biochem Pharmacol 2013; 87:360-70. [PMID: 24184507 DOI: 10.1016/j.bcp.2013.10.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 10/17/2013] [Accepted: 10/18/2013] [Indexed: 01/06/2023]
Abstract
Pregnane X receptor (PXR) is a xenobiotic sensor regulating the expression of genes involved in xenobiotic detoxification and elimination. Phosphorylation plays an important role in modulating PXR activity and several phosphorylation sites have been predicted and characterized in in vitro experiments. Although PXR has been shown to be a phosphoprotein in vivo, the exact residues that are phosphorylated remain elusive. Using mass spectrometry, we identified for the first time S114, T133/135, S167, and S200 residues that are phosphorylated in PXR following an in vitro kinase assay using cyclin-dependent kinase 2. We further found that the phosphorylation at S114, T133, and T135 occurred in PXR isolated from cells. We tested the phosphodeficient and phosphomimetic mutants corresponding to all the sites identified and determined that phosphorylation at S114 attenuates the transcriptional activity of PXR, consistent with the observation that the S114D mutant displayed reduced association with the PXR-targeted DNA response element. Phosphomimetic mutations at either T133 or T135 did not show a significant change in transcriptional activity however, the dual phosphomimetic mutant T133D/T135D displayed reduced transcriptional activity. Subcellular localization studies showed a varied distribution of the mutants suggesting that the regulation of PXR is much more complex than what we can observe by just overexpressing the mutants. Thus, our results provide the first direct evidence that PXR is phosphorylated at specific residues and suggest that further investigation is warranted to fully understand the regulation of PXR by phosphorylation.
Collapse
Affiliation(s)
- Ayesha Elias
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Anthony A High
- St. Jude Proteomics Facility, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Ashutosh Mishra
- St. Jude Proteomics Facility, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Su Sien Ong
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Jing Wu
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Junmin Peng
- St. Jude Proteomics Facility, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA; Departments of Structural Biology and Developmental Neurobiology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
| |
Collapse
|
26
|
Banerjee M, Chen T. Differential regulation of CYP3A4 promoter activity by a new class of natural product derivatives binding to pregnane X receptor. Biochem Pharmacol 2013; 86:824-35. [PMID: 23928187 DOI: 10.1016/j.bcp.2013.07.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 07/25/2013] [Accepted: 07/26/2013] [Indexed: 01/25/2023]
Abstract
The pregnane X receptor (PXR) regulates drug metabolism by regulating the expression of drug-metabolizing enzymes such as cytochrome P450 3A4 (CYP3A4), which is involved in the metabolism of >50% of clinically prescribed drugs. The activity of PXR can be controlled by the binding of small molecule agonists or antagonists. Because of its unique ligand binding pocket, PXR binds promiscuously to structurally diverse chemicals. To study the structure-activity relationship, novel modulators for PXR are needed. Here we report the virtual screening of ∼25,000 natural product derivatives from the ZINC database using the Molecular Operating Environment docking software tool against the PXR-rifampicin complex X-ray crystal structure. Our screening resulted in identification of compounds based on the lowest S score, which measures Gibbs free energy. Interestingly, we found that the compounds that bind directly to PXR, as revealed in an intrinsic tryptophan fluorescence assay, modulate CYP3A4 promoter activity differentially in HepG2 cells. Mutational analysis and docking studies showed that these compounds bind broadly in the ligand binding pocket but interact with different amino acid residues. We further investigated the mechanism of binding by analyzing the functional groups that are important for distinguishing agonists from antagonists. The approach we used to identify novel modulators that bind to PXR can be useful for finding novel modulators of PXR.
Collapse
Affiliation(s)
- Monimoy Banerjee
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | | |
Collapse
|
27
|
Hirooka-Masui K, Lesmana R, Iwasaki T, Xu M, Hayasaka K, Haraguchi M, Takeshita A, Shimokawa N, Yamamoto K, Koibuchi N. Interaction of silencing mediator for retinoid and thyroid receptors with steroid and xenobiotic receptor on multidrug resistance 1 promoter. Life Sci 2013; 92:911-5. [PMID: 23562850 DOI: 10.1016/j.lfs.2013.03.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 02/22/2013] [Accepted: 03/15/2013] [Indexed: 11/16/2022]
Abstract
AIMS The steroid and xenobiotic receptor (SXR) regulates the transcription of its target genes by interacting with various nuclear receptor cofactors. We have previously shown that silencing mediator for retinoid and thyroid receptors (SMRT) interacts with SXR even in the presence of rifampicin on cytochrome P450 monooxygenase 3A4 (CYP3A4) promoter in HepG2 cells. To examine the specificity of such interaction, the involvement of SMRT on SXR-mediated transcription through multidrug resistance (MDR) 1 gene promoter was examined using LS174T intestine-derived clonal cells. MAIN METHODS Transient transfection-based reporter gene assay was carried out to examine the effect of SMRT or nuclear receptor corepressor (NCoR) on SXR-mediated transcription in LS174T cells. Semi-quantitative RT-PCR was performed to confirm the expression of MDR1 mRNA in LS174T cells. To examine the interaction of SMRT with SXR, we carried out mammalian one-hybrid assay in CV-1 cells and immunoprecipitation study in HEK-293 cells. KEY FINDINGS SMRT, but not NCoR suppressed rifampicin-induced SXR-mediated transcription. The SXR-mediated MDR1 mRNA expression was augmented in the presence of rifampicin, whereas it suppressed the expression following the overexpression of SMRT. In mammalian one-hybrid assay, only SMRT but not NCoR interacted with SXR on MDR1 promoter in the presence of rifampicin. In immunoprecipitation study, SMRT bound to SXR regardless of the presence or absence of rifampicin. SIGNIFICANCE SMRT may be recruited in the SXR-cofactor complex even in the presence of ligand. SMRT may be involved not only in SXR-mediated suppression without ligand, but also in ligand-activated transcription to suppress the overactivation of transcription.
Collapse
Affiliation(s)
- Kazumi Hirooka-Masui
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Elias A, Wu J, Chen T. Tumor suppressor protein p53 negatively regulates human pregnane X receptor activity. Mol Pharmacol 2013; 83:1229-36. [PMID: 23536728 DOI: 10.1124/mol.113.085092] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human pregnane X receptor (PXR) regulates genes involved in drug metabolism and disposition. PXR associates with multiple corepressors that attenuate and coactivators that enhance its activity. PXR plays a vital role in the drug metabolism pathway, and a comprehensive examination of PXR-associated proteins will provide greater insight into the regulation of the receptor and possible therapeutic implications. We performed a mass spectrometric screen to identify PXR-associated proteins. Here we report that the tumor suppressor protein p53 can associate with PXR and downregulate its activity. A loss-of-function p53 mutant (R175H) interacts with PXR but does not repress its activity. Mutant p53 can relieve the suppressive effect of wild-type p53 by competing with its interaction with PXR, suggesting that protein-protein interaction is required but not sufficient for p53 to repress PXR activity. Interestingly, a PXR variant with a naturally occurring deletion of a conserved, unique sequence in the ligand binding domain (PXR174-210) did not interact with p53, indicating that the PXR-p53 interaction is specific. Using a chromatin immunoprecipitation assay, we showed that p53 inhibits the binding of PXR to the CYP3A4 promoter. The loss of p53 function in tumor cells leads to aberrant cell proliferation, apoptosis, carcinogenesis, and altered sensitivity to chemotherapeutic drugs, whereas PXR contributes to chemoresistance in many cancer cells. Our findings show for the first time that wild-type p53 can negatively regulate PXR by physically associating with it. Thus, PXR and p53 appear to play important yet opposing roles in the sensitivity of tumor cells to chemotherapy.
Collapse
Affiliation(s)
- Ayesha Elias
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105-3678, USA
| | | | | |
Collapse
|
29
|
Rana R, Coulter S, Kinyamu H, Goldstein JA. RBCK1, an E3 ubiquitin ligase, interacts with and ubiquinates the human pregnane X receptor. Drug Metab Dispos 2012; 41:398-405. [PMID: 23160820 DOI: 10.1124/dmd.112.048728] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The pregnane X receptor (PXR, NR1I2) plays a pivotal role in the disposition and detoxification of numerous foreign and endogenous chemicals by increasing transcription of numerous target genes, including phase I and II drug-metabolizing enzymes and transporters. In the present study, yeast two-hybrid screening identified an E3 ubiquitin ligase, RBCK1 (Ring-B-box-coiled-coil protein interacting with protein kinase C-1), as a human pregnane X receptor (hPXR)-interacting protein. Coimmunoprecipitation studies confirmed the interaction between RBCK1 and hPXR when both were ectopically expressed in AD-293 cells. Domain mapping studies showed that the interaction between RBCK1 and hPXR involves all RBCK1 domains. We further demonstrate that RBCK1 ubiquitinates hPXR, and this may target hPXR for degradation by the ubiquitin-proteasome pathway. Simultaneous ectopic overexpression of RBCK1 and PXR decreased PXR levels in AD-293 cells, and this decrease was inhibited by the proteasomal inhibitor MG-132 (carbobenzoxy-Leu-Leu-leucinal). Furthermore, overexpression of RBCK1 decreased endogenous levels of PXR in HepG2 cells. Of importance, ectopic overexpression and silencing of endogenous RBCK1 in primary human hepatocytes resulted in a decrease and increase, respectively, in endogenous PXR protein levels and in the induction of PXR target genes by rifampicin. These results suggest that RBCK1 is important for the ubiquitination of PXR and may play a role in its proteasomal degradation.
Collapse
Affiliation(s)
- Ritu Rana
- Laboratory of Toxicology & Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | | | | | | |
Collapse
|
30
|
Pregnane xenobiotic receptor in cancer pathogenesis and therapeutic response. Cancer Lett 2012; 328:1-9. [PMID: 22939994 DOI: 10.1016/j.canlet.2012.08.030] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 08/20/2012] [Accepted: 08/22/2012] [Indexed: 01/24/2023]
Abstract
Pregnane xenobiotic receptor (PXR) is an orphan nuclear receptor that regulates the metabolism of endobiotics and xenobiotics. PXR is promiscuous and unique in that it is activated by a diverse group of xenochemicals, including therapeutic anticancer drugs and naturally-occurring endocrine disruptors. PXR has been predominantly studied to understand its regulatory role in xenobiotic clearance in liver and intestine via induction of drug metabolizing enzymes and drug transporters. PXR, however, is widely expressed and has functional implications in other normal and malignant tissues, including breast, prostate, ovary, endometrium and bone. The differential expression of PXR and its target genes in cancer tissues has been suggested to determine the prognosis of chemotherapeutic outcome. In addition, the emerging evidence points to the implications of PXR in regulating apoptotic and antiapoptotic as well as growth factor signaling that promote tumor proliferation and metastasis. In this review, we highlight the recent progress made in understanding the role of PXR in cancer, discuss the future directions to further understand the mechanistic role of PXR in cancer, and conclude with the need to identify novel selective PXR modulators.
Collapse
|
31
|
Li T, Yu RT, Atkins AR, Downes M, Tukey RH, Evans RM. Targeting the pregnane X receptor in liver injury. Expert Opin Ther Targets 2012; 16:1075-83. [PMID: 22913318 DOI: 10.1517/14728222.2012.715634] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION The nuclear receptor pregnane X receptor (PXR) is a well-characterized hepatic xenobiotic sensor whose activation by chemically diverse compounds results in the induction of drug clearance pathways that rid the body of potentially toxic substances, thus conferring protection from foreign chemicals and endobiotics. AREAS COVERED PXR activities are implicated in drug-drug interactions and endocrine disruption. Recent evidence supports a hepatoprotective role for PXR in chronic liver injury, inhibiting liver inflammation through suppression of the NF-κB pathway. However, PXR-mediated induction of CYP3A enhances APAP-induced acute liver injury by generating toxic metabolites. While these observations implicate PXR as a therapeutic target for liver injury, they also caution against PXR activation by pharmaceutical drugs. EXPERT OPINION While evidence of PXR involvement in acute and chronic liver injuries identifies it as a possible therapeutic target, it raises additional concerns for all drug candidates. The in vitro and in vivo tests for human PXR activation should be incorporated into the FDA regulations for therapeutic drug approval to identify potential liver toxicities. In addition, PXR pharmacogenetic studies will facilitate the prediction of patient-specific drug reactivities and associated liver disorders.
Collapse
Affiliation(s)
- Tao Li
- The Salk Institute for Biological Studies, Gene Expression Laboratory, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | | | | | | | | | |
Collapse
|
32
|
Chen S, Yueh MF, Evans RM, Tukey RH. Pregnane-x-receptor controls hepatic glucuronidation during pregnancy and neonatal development in humanized UGT1 mice. Hepatology 2012; 56:658-67. [PMID: 22371261 PMCID: PMC3383890 DOI: 10.1002/hep.25671] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 02/13/2012] [Indexed: 02/01/2023]
Abstract
UNLABELLED In humanized UDP glucuronosyltransferase-1 (hUGT1) mice that express the entire UGT1 locus, the maternal hepatic UGT1A genes are dramatically induced 12-14 days after conception. Steroid induction of the UGT1A1 gene indicates that xenobiotic sensors, such as the pregnane X receptor (PXR) and constitutive androstane receptor (CAR), may underlie the induction process. In contrast, neonatal hUGT1 mice display severe hyperbilirubinemia, with limited expression of the UGT1A genes. This study identifies PXR as both a positive and negative regulator of the UGT1A1 gene. Pregnancy hormones, in particular the glucocorticoids, target PXR as a positive regulator of human glucuronidation. Employing reverse genetics, where PXR has been genetically deleted, hUGT1/Pxr(-/-) mice show limited induction of the liver UGT1A genes during pregnancy, whereas the exact opposite occurs in newborn mice. Neonatal hUGT1 mice show delayed expression of hepatic UGT1A1 and are severely hyperbilirubinemic. However, in hUGT1/Pxr(-/-) mice, hyperbilirubinemia is greatly reduced due to induction of hepatic UGT1A1. Thus, PXR serves to repress UGT1A1 gene expression during development. Transcriptional silencing of the UGT1A1 gene was relieved in neonatal hUGT1 hepatocytes through interruption of PXR by small interfering RNA. CONCLUSION PXR is a key regulator of pregnancy induced glucuronidation capacity in addition to modulating the severity of neonatal jaundice.
Collapse
Affiliation(s)
- Shujuan Chen
- Department of Pharmacology, Laboratory of Environmental Toxicology, University of CaliforniaSan Diego, La Jolla, CA
| | - Mei-Fei Yueh
- Department of Pharmacology, Laboratory of Environmental Toxicology, University of CaliforniaSan Diego, La Jolla, CA
| | - Ronald M Evans
- Howard Hughes Medical Institute and Gene Expression Laboratory, Salk Institute of Biological StudiesLa Jolla, CA
| | - Robert H Tukey
- Department of Pharmacology, Laboratory of Environmental Toxicology, University of CaliforniaSan Diego, La Jolla, CA,Department of Chemistry & Biochemistry, Laboratory of Environmental Toxicology, University of CaliforniaSan Diego, La Jolla, CA
| |
Collapse
|
33
|
Takezawa T, Matsunaga T, Aikawa K, Nakamura K, Ohmori S. Lower Expression of HNF4α and PGC1α Might Impair Rifampicin-mediated CYP3A4 Induction under Conditions Where PXR Is Overexpressed in Human Fetal Liver Cells. Drug Metab Pharmacokinet 2012; 27:430-8. [DOI: 10.2133/dmpk.dmpk-11-rg-126] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
34
|
Navaratnarajah P, Steele BL, Redinbo MR, Thompson NL. Rifampicin-independent interactions between the pregnane X receptor ligand binding domain and peptide fragments of coactivator and corepressor proteins. Biochemistry 2011; 51:19-31. [PMID: 22185585 DOI: 10.1021/bi2011674] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The pregnane X receptor (PXR), a member of the nuclear receptor superfamily, regulates the expression of drug-metabolizing enzymes in a ligand-dependent manner. The conventional view of nuclear receptor action is that ligand binding enhances the receptor's affinity for coactivator proteins, while decreasing its affinity for corepressors. To date, however, no known rigorous biophysical studies have been conducted to investigate the interaction among PXR, its coregulators, and ligands. In this work, steady-state total internal reflection fluorescence microscopy (TIRFM) and total internal reflection with fluorescence recovery after photobleaching were used to measure the thermodynamics and kinetics of the interaction between the PXR ligand binding domain and a peptide fragment of the steroid receptor coactivator-1 (SRC-1) in the presence and absence of the established PXR agonist, rifampicin. Equilibrium dissociation and dissociation rate constants of ~5 μM and ~2 s(-1), respectively, were obtained in the presence and absence of rifampicin, indicating that the ligand does not enhance the affinity of the PXR and SRC-1 fragments. Additionally, TIRFM was used to examine the interaction between PXR and a peptide fragment of the corepressor protein, the silencing mediator for retinoid and thyroid receptors (SMRT). An equilibrium dissociation constant of ~70 μM was obtained for SMRT in the presence and absence of rifampicin. These results strongly suggest that the mechanism of ligand-dependent activation in PXR differs significantly from that seen in many other nuclear receptors.
Collapse
Affiliation(s)
- Punya Navaratnarajah
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260, United States
| | | | | | | |
Collapse
|
35
|
Liu YH, Mo SL, Bi HC, Hu BF, Li CG, Wang YT, Huang L, Huang M, Duan W, Liu JP, Wei MQ, Zhou SF. Regulation of human pregnane X receptor and its target gene cytochrome P450 3A4 by Chinese herbal compounds and a molecular docking study. Xenobiotica 2010; 41:259-80. [PMID: 21117944 DOI: 10.3109/00498254.2010.537395] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The pregnane X receptor (PXR) plays a critical role in the regulation of human cytochrome P450 3A4 (CYP3A4) gene. In this study, we investigated the effect of an array of compounds isolated from Chinese herbal medicines on the activity of PXR using a luciferase reporter gene assay in transiently transfected HepG2 and Huh7 cells and on the expression of PXR and CYP3A4 in LS174T cells. Furthermore, molecular docking was performed to investigate the binding modes of herbal compounds with PXR. Praeruptorin A and C, salvianolic acid B, sodium danshensu, protocatechuic aldehyde, cryptotanshinone, emodin, morin, and tanshinone IIA significantly transactivated the CYP3A4 reporter gene construct in either HepG2 or Huh7 cells. The PXR mRNA expression in LS174T cells was significantly induced by physcion, protocatechuic aldehyde, salvianolic acid B, and sodium danshensu. However, epifriedelanol, morin, praeruptorin D, mulberroside A, tanshinone I, and tanshinone IIA significantly down-regulated the expression of PXR mRNA in LS174T cells. All the herbal compounds tested can be readily docked into the ligand-binding cavity of PXR mainly through hydrogen bond and aromatic interactions with Ser247, Gln285, His407, and Arg401. These findings suggest that herbal medicines can significantly regulate PXR and CYP3A4 and this has important implication in herb-drug interactions.
Collapse
Affiliation(s)
- Ya-He Liu
- School of Health Sciences & Health Innovations Research Institute, RMIT University, Bundoora, Victoria, Australia
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Overcoming drug resistance by regulating nuclear receptors. Adv Drug Deliv Rev 2010; 62:1257-64. [PMID: 20691230 DOI: 10.1016/j.addr.2010.07.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 07/21/2010] [Accepted: 07/23/2010] [Indexed: 12/12/2022]
Abstract
Drug resistance involves multiple mechanisms. Multidrug resistance (MDR) is the leading cause of treatment failure in cancer therapy. Elevated levels of MDR proteins [members of the ATP-binding cassette (ABC) transporter family] increase cellular efflux and decrease the effectiveness of chemotherapeutic agents. As a salvage approach to overcome drug resistance, inhibitors of MDR proteins have been developed, but have had limited success mainly due to undesired toxicities. Nuclear receptors (NRs), including pregnane X receptor (PXR), regulate the expression of proteins (including MDR proteins) involved in drug metabolism and drug clearance, suggesting that it is possible to overcome drug resistance by regulating NR. This review discusses the progress in the development of MDR inhibitors, with a focus on MDR1 inhibitors. Recent development of PXR antagonists to pharmacologically modulate PXR is also reviewed. The review proposes that selectively preventing the elevation of MDR levels by regulating NRs rather than non-selectively inhibiting the MDR activity by using MDR inhibitors can be a less toxic approach to overcome drug resistance during cancer therapy.
Collapse
|
37
|
Küblbeck J, Reinisalo M, Mustonen R, Honkakoski P. Up-regulation of CYP expression in hepatoma cells stably transfected by chimeric nuclear receptors. Eur J Pharm Sci 2010; 40:263-72. [DOI: 10.1016/j.ejps.2010.03.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 03/22/2010] [Accepted: 03/30/2010] [Indexed: 10/19/2022]
|
38
|
Pondugula SR, Tong AA, Wu J, Cui J, Chen T. Protein phosphatase 2Cbetal regulates human pregnane X receptor-mediated CYP3A4 gene expression in HepG2 liver carcinoma cells. Drug Metab Dispos 2010; 38:1411-6. [PMID: 20538721 DOI: 10.1124/dmd.110.032128] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The human pregnane X receptor (hPXR) regulates the expression of CYP3A4, which plays a vital role in hepatic drug metabolism and has considerably reduced expression levels in proliferating hepatocytes. We have recently shown that cyclin-dependent kinase 2 (CDK2) negatively regulates hPXR-mediated CYP3A4 gene expression. CDK2 can be dephosphorylated and inactivated by protein phosphatase type 2C beta isoform long (PP2Cbetal), a unique phosphatase that was originally cloned from human liver. In this study, we sought to determine whether PP2Cbetal is involved in regulating hPXR's transactivation activity and whether PP2Cbetal affects CDK2 regulation of this activity in HepG2 liver carcinoma cells. In transactivation assays, transiently coexpressed PP2Cbetal significantly enhanced the hPXR-mediated CYP3A4 promoter activity and decreased the inhibitory effect of CDK2 on hPXR transactivation activity. In addition, shRNA-mediated down-regulation of endogenous PP2Cbetal promoted cell proliferation, inhibited the interaction of hPXR with steroid receptor coactivator-1, and attenuated the hPXR transcriptional activity. The levels of PP2Cbetal did not affect hPXR expression. Our results show for the first time that PP2Cbetal is essential for hPXR activity and can positively regulate this activity by counteracting the inhibitory effect of CDK2. Our results implicate a novel and important role for PP2Cbetal in regulating hPXR activity and CYP3A4 expression by inhibiting or desensitizing signaling pathways that negatively regulate the function of pregnane X receptor in liver cells and are consistent with the notion that both the activity of hPXR and the expression of CYP3A4 are regulated in a cell cycle-dependent and cell proliferation-dependent manner.
Collapse
Affiliation(s)
- Satyanarayana R Pondugula
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | | | | | | | | |
Collapse
|
39
|
Pondugula SR, Dong H, Chen T. Phosphorylation and protein-protein interactions in PXR-mediated CYP3A repression. Expert Opin Drug Metab Toxicol 2009; 5:861-73. [PMID: 19505191 DOI: 10.1517/17425250903012360] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND The expression of drug-metabolizing enzymes CYPs is controlled by pregnane X receptor (PXR), and, therefore, understanding how PXR modulates CYP expression is important to minimize adverse drug interactions, one type of preventable adverse drug reaction. OBJECTIVE We review the mechanisms of PXR-mediated repression of CYP expression. METHODS We discuss the clinical implications of CYP repression and the role of signal cross-talks, including protein-protein interactions and phosphorylation of PXR and coregulators, in inhibiting PXR and repressing CYP expression. RESULTS/CONCLUSION Kinases such as cyclin-dependent kinase 2, protein kinase A, PKC and 70 kDa form of ribosomal protein S6 kinase repress CYP expression by phosphorylating and inhibiting PXR. Growth factor signaling represses CYP expression by phosphorylating and inhibiting forkhead in rhabdomyosarcoma, a co-activator of PXR. During inflammation, NF-kappaB represses both PXR and CYP expression through protein-protein interactions with the PXR pathway.
Collapse
Affiliation(s)
- Satyanarayana R Pondugula
- St. Jude Children's Research Hospital, Department of Chemical Biology and Therapeutics, 262 Danny Thomas Place, Mail Stop 1000, Memphis, TN 38105, USA
| | | | | |
Collapse
|
40
|
Lin YS, Yasuda K, Assem M, Cline C, Barber J, Li CW, Kholodovych V, Ai N, Chen JD, Welsh WJ, Ekins S, Schuetz EG. The major human pregnane X receptor (PXR) splice variant, PXR.2, exhibits significantly diminished ligand-activated transcriptional regulation. Drug Metab Dispos 2009; 37:1295-304. [PMID: 19251824 DOI: 10.1124/dmd.108.025213] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The pregnane X receptor (PXR; PXR.1) can be activated by structurally diverse lipophilic ligands. PXR.2, an alternatively spliced form of PXR, lacks 111 nucleotides encoding 37 amino acids in the ligand binding domain. PXR.2 bound a classic CYP3A4 PXR response element (PXRE) in electrophoretic mobility shift assays, but transfected PXR.2 failed to transactivate a CYP3A4-promoter-luciferase reporter plasmid in HepG2 cells treated with various PXR ligands. Cotransfection experiments showed that PXR.2 behaved as a dominant negative, interfering with PXR.1/rifampin activation of CYP3A4-PXRE-LUC. In HepG2 and LS180 cells stably transduced with PXR.1, PXR target genes (CYP3A4, MDR1, CYP2B6, and UGT1A1) were higher than mock-transduced cells in the absence of ligand and were further induced in the presence of rifampin. In contrast, PXR.2 stably introduced into the same host cells failed to induce target genes over levels in mock-transfected cells after drug treatment. Our homology modeling suggests that ligands bind PXR.1 more favorably, probably because of the presence of a key disordered loop region, which is missing in PXR.2. Yeast two-hybrid assays revealed that, even in the presence of ligand, the corepressors remain tightly bound to PXR.2, and coactivators are unable to bind at helix 12. In summary, PXR.2 can bind to PXREs but fails to transactivate target genes because ligands do not bind the ligand binding domain of PXR.2 productively, corepressors remain tightly bound, and coactivators are not recruited to PXR.2.
Collapse
Affiliation(s)
- Yvonne S Lin
- Department of Pharmaceutical Sciences, St. Jude Children's Hospital, Memphis, TN 38105, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Pondugula SR, Brimer-Cline C, Wu J, Schuetz EG, Tyagi RK, Chen T. A phosphomimetic mutation at threonine-57 abolishes transactivation activity and alters nuclear localization pattern of human pregnane x receptor. Drug Metab Dispos 2009; 37:719-30. [PMID: 19171678 DOI: 10.1124/dmd.108.024695] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The pregnane X receptor (PXR) plays crucial roles in multiple physiological processes. However, the signaling mechanisms responsible are not well defined; it is most likely that multiple functions of PXR are modulated by its phosphorylation. Therefore, we sought to determine whether mutation at a highly conserved Thr(57) affects human PXR (hPXR) function. Site-directed mutagenesis was performed to generate phosphorylation-deficient (hPXR(T57A)) and phosphomimetic (hPXR(T57D)) mutants. Gene reporter, Western blotting, immunocytochemistry, mammalian two-hybrid, and electrophoretic mobility shift assays were used to study cytochrome P450 3A4 (CYP3A4) promoter activation, protein levels, localization, cofactor interaction, and CYP3A4 promoter binding of the hPXR mutants, respectively. hPXR(T57D), but not hPXR(T57A), lost its transcriptional activity. Neither mutation altered hPXR's protein levels and interaction with steroid receptor coactivator-1. hPXR and hPXR(T57A) exhibited a homogenous nuclear distribution, whereas hPXR(T57D) exhibited a distinctive punctate nuclear localization pattern similar to that of hPXR mutants with impaired function that colocalize with silencing mediator of retinoid and thyroid receptors (SMRT), although silencing of SMRT did not rescue the altered function of hPXR(T57D). However, hPXR(T57D), but not hPXR(T57A), impaired hPXR's ability to bind to the CYP3A4 promoter, consistent with the mutant's transactivation function. Furthermore, the 70-kDa form of ribosomal protein S6 kinase (p70 S6K) phosphorylated hPXR in vitro and inhibited its transcriptional activity, whereas hPXR(T57A) partially resisted the inhibitory effect of p70 S6K. Our studies identify a functionally significant phosphomimetic mutant (hPXR(T57D)) and show p70 S6K phosphorylation and regulation of hPXR transactivation to support the notion that phosphorylation plays important roles in regulating hPXR function.
Collapse
Affiliation(s)
- Satyanarayana R Pondugula
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Mail Stop 1000, Memphis, TN 38105, USA
| | | | | | | | | | | |
Collapse
|
42
|
Li CW, Dinh GK, Chen JD. Preferential physical and functional interaction of pregnane X receptor with the SMRTalpha isoform. Mol Pharmacol 2008; 75:363-73. [PMID: 18978041 DOI: 10.1124/mol.108.047845] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The silencing mediator for retinoid and thyroid hormone receptors (SMRT) serves as a platform for transcriptional repression elicited by several steroid/nuclear receptors and transcription factors. SMRT exists in two major splicing isoforms, alpha and tau, with SMRTalpha containing only an extra 46-amino acid sequence inserted immediately downstream from the C-terminal corepressor motif. Little is known about potential functional differences between these two isoforms. Here we show that the pregnane X receptor (PXR) interacts more strongly with SMRTalpha than with SMRTtau both in vitro and in vivo. It is interesting that the PXR-SMRTalpha interaction is also resistant to PXR ligand-induced dissociation, in contrast to the PXR-SMRTtau interaction. SMRTalpha consistently inhibits PXR activity more efficiently than does SMRTtau in transfection assays, although they possess comparable intrinsic repression activity and association with histone deacetylase. We further show that the mechanism for the enhanced PXR-SMRTalpha interaction involves both the 46-amino acid insert and the C-terminal corepressor motif. In particular, the first five amino acids of the SMRTalpha insert are essential and sufficient for the enhanced binding of SMRTalpha to PXR. Furthermore, we demonstrate that Tyr2354 and Asp2355 residues of the SMRTalpha insert are most critical for the enhanced interaction. In addition, expression data show that SMRTalpha is more abundantly expressed in most human tissues and cancer cell lines, and together these data suggest that SMRTalpha may play a more important role than SMRTtau in the negative regulation of PXR.
Collapse
Affiliation(s)
- Chia-Wei Li
- Department of Pharmacology,University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5635, USA
| | | | | |
Collapse
|
43
|
Fox JE, Burow ME, McLachlan JA, Miller CA. Detecting ligands and dissecting nuclear receptor-signaling pathways using recombinant strains of the yeast Saccharomyces cerevisiae. Nat Protoc 2008; 3:637-45. [PMID: 18388946 DOI: 10.1038/nprot.2008.33] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This is a general protocol for the identification of natural and xenobiotic ligands of metazoan nuclear receptors (NRs) expressed in yeast. Yeast engineered to express an NR and a response element-driven reporter gene provide a system to detect and quantify ligand-dependent transcriptional activity. Such assays allow researchers to measure different types of ligands and determine dose-dependent activation of NRs. This methodology can also be used to examine the components of signal transduction pathways when conducted with mutant or engineered yeast strains expressing additional proteins or having alternate DNA response elements. This assay typically takes 2-3 d to complete, but most of this time entails cell growth rather than 'hands on' time.
Collapse
Affiliation(s)
- Jennifer E Fox
- Center for Ecology and Evolutionary Biology, University of Oregon, Eugene, Oregon 97403, USA
| | | | | | | |
Collapse
|
44
|
Abstract
Over the last 25 years roles have been established for vitamin D receptor (VDR) in influencing cell proliferation and differentiation. For example, murine knock-out approaches have revealed a role for the VDR in controlling mammary gland growth and function. These actions appear widespread, as the enzymes responsible for 1alpha,25-dihydroxycholecalciferol generation and degradation, and the VDR itself, are all functionally present in a wide range of epithelial and haematopoietic cell types. These findings, combined with epidemiological and functional data, support the concept that local, autocrine and paracrine VDR signalling exerts control over cell-fate decisions in multiple cell types. Furthermore, the recent identification of bile acid lithocholic acid as a VDR ligand underscores the environmental sensing role for the VDR. In vitro and in vivo dissection of VDR signalling in cancers (e.g. breast, prostate and colon) supports a role for targeting the VDR in either chemoprevention or chemotherapy settings. As with other potential therapeutics, it has become clear that cancer cells display de novo and acquired genetic and epigenetic mechanisms of resistance to these actions. Consequently, a range of experimental and clinical options are being developed to bring about more targeted actions, overcome resistance and enhance the efficacy of VDR-centred therapeutics.
Collapse
|
45
|
Ankyrin repeats-containing cofactors interact with ADA3 and modulate its co-activator function. Biochem J 2008; 413:349-57. [PMID: 18377363 DOI: 10.1042/bj20071484] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
ANCO (ankyrin repeats-containing cofactor)-1 and ANCO-2 are a family of unique transcriptional co-regulators with dual properties: they interact with both the co-activators and the co-repressors [Zhang, Yeung, Li, Tsai, Dinh, Wu, Li and Chen (2004) J. Biol. Chem. 279, 33799-33805]. Specifically, ANCO-1 is thought to recruit HDACs (histone deacetylases) to the p160 co-activator to repress transcriptional activation by nuclear receptors. In the present study, we provide new evidence to suggest further that ANCO-1 and ANCO-2 also interact with the co-activator ADA3 (alteration/deficiency in activation 3). The interaction occurs between the conserved C-terminal domain of ANCO-1 and the N-terminal transactivation domain of ADA3. Several subunits of the P/CAF {p300/CBP [CREB (cAMP-response-element-binding protein)-binding protein]-associated factor} complex, including ADA3, ADA2alpha/beta and P/CAF, showed co-localization with ANCO-1 nuclear dots, indicating an in vivo association of ANCO-1 with the P/CAF complex. Furthermore, a transient reporter assay revealed that both ANCO-1 and ANCO-2 repress ADA3-mediated transcriptional co-activation on nuclear receptors, whereas ANCO-1 stimulated p53-mediated transactivation. These data suggest that ADA3 is a newly identified target of the ANCO proteins, which may modulate co-activator function in a transcription-factor-specific manner.
Collapse
|
46
|
Ekins S, Kholodovych V, Ai N, Sinz M, Gal J, Gera L, Welsh WJ, Bachmann K, Mani S. Computational discovery of novel low micromolar human pregnane X receptor antagonists. Mol Pharmacol 2008; 74:662-72. [PMID: 18579710 DOI: 10.1124/mol.108.049437] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Very few antagonists have been identified for the human pregnane X receptor (PXR). These molecules may be of use for modulating the effects of therapeutic drugs, which are potent agonists for this receptor (e.g., some anticancer compounds and macrolide antibiotics), with subsequent effects on transcriptional regulation of xenobiotic metabolism and transporter genes. A recent novel pharmacophore for PXR antagonists was developed using three azoles and consisted of two hydrogen bond acceptor regions and two hydrophobic features. This pharmacophore also suggested an overall small binding site that was identified on the outer surface of the receptor at the AF-2 site and validated by docking studies. Using computational approaches to search libraries of known drugs or commercially available molecules is preferred over random screening. We have now described several new smaller antagonists of PXR discovered with the antagonist pharmacophore with in vitro activity in the low micromolar range [S-p-tolyl 3',5-dimethyl-3,5'-biisoxazole-4'-carbothioate (SPB03255) (IC(50), 6.3 microM) and 4-(3-chlorophenyl)-5-(2,4-dichlorobenzylthio)-4H-1,2,4-triazol-3-ol (SPB00574) (IC(50), 24.8 microM)]. We have also used our computational pharmacophore and docking tools to suggest that most of the known PXR antagonists, such as coumestrol and sulforaphane, could also interact on the outer surface of PXR at the AF-2 domain. The involvement of this domain was also suggested by further site-directed mutagenesis work. We have additionally described an FDA approved prodrug, leflunomide (IC(50), 6.8 microM), that seems to be a PXR antagonist in vitro. These observations are important for predicting whether further molecules may interact with PXR as antagonists in vivo with potential therapeutic applications.
Collapse
Affiliation(s)
- Sean Ekins
- Collaborations in Chemistry, Jenkintown, PA 19046, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Rokutanda N, Iwasaki T, Odawara H, Nagaoka R, Miyazaki W, Takeshita A, Koibuchi Y, Horiguchi J, Shimokawa N, Iino Y, Morishita Y, Koibuchi N. Augmentation of estrogen receptor-mediated transcription by steroid and xenobiotic receptor. Endocrine 2008; 33:305-16. [PMID: 19011999 DOI: 10.1007/s12020-008-9091-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Accepted: 06/07/2008] [Indexed: 10/21/2022]
Abstract
The estrogen receptor (ER) is a key regulator of proliferation and differentiation in breast cancer cells. In the present study, the effect of steroid and xenobiotic receptor (SXR) on 17/beta-estradiol (E2)-induced transcription through ERalpha was studied. SXR augmented ER-mediated transcription in the presence of E2 in MCF-7 breast cancer-derived cells and CV-1 fibroblast-derived cells. On the other hand, SXR alone did not affect the estrogen response element (ERE)-containing promoter activity in CV-1 cells. SXR did not directly bind to ERalpha or ERE in vitro, indicating that SXR may affect ER-mediated transcription by altering cofactor binding to ER. Although SXR did not alter the binding between ERalpha and p300/CBP interacting protein (p/CIP), it decreased the binding of a specific corepressor, silencing mediator of retinoid and thyroid hormone receptors (SMRT) to liganded ERalpha as assessed by mammalian two-hybrid, glutathione S-transferase pull-down, immunoprecipitation and newly developed Liquid Chemiluminescent DNA Pull-Down Assays. These results indicate that SXR augmented ER-mediated transcription by dissociating SMRT from ERalpha. Thus, the expression of SXR in breast cancer cells may alter the ER signaling, which may play crucial role for growth and differentiation of breast cancer cells.
Collapse
MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Base Sequence
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Cell Differentiation/drug effects
- Cell Differentiation/physiology
- Cell Division/drug effects
- Cell Division/physiology
- Cell Line, Tumor
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Dose-Response Relationship, Drug
- Estradiol/pharmacology
- Estrogen Receptor alpha/genetics
- Estrogen Receptor alpha/metabolism
- Gene Expression Regulation, Neoplastic/drug effects
- Gene Expression Regulation, Neoplastic/physiology
- Humans
- Nuclear Receptor Co-Repressor 2
- Pregnane X Receptor
- Promoter Regions, Genetic/physiology
- Receptors, Steroid/genetics
- Receptors, Steroid/metabolism
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Signal Transduction/physiology
- Transcription, Genetic/drug effects
- Transcription, Genetic/physiology
Collapse
Affiliation(s)
- Nana Rokutanda
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Lemaire G, Benod C, Nahoum V, Pillon A, Boussioux AM, Guichou JF, Subra G, Pascussi JM, Bourguet W, Chavanieu A, Balaguer P. Discovery of a Highly Active Ligand of Human Pregnane X Receptor: A Case Study from Pharmacophore Modeling and Virtual Screening to “In Vivo” Biological Activity. Mol Pharmacol 2007; 72:572-81. [PMID: 17573484 DOI: 10.1124/mol.106.033415] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human pregnane X receptor (hPXR) is a nuclear receptor that regulates the expression of phase I and II drug-metabolizing enzymes as well as that of drug transporters. In addition, this receptor plays a critical role in cholesterol homeostasis and in protecting tissues from potentially toxic endobiotics. hPXR is activated by a broad spectrum of low-affinity compounds including xenobiotics and endobiotics such as bile acids and their precursors. Crystallographic studies revealed a ligand binding domain (LBD) with a large and conformable binding pocket that is likely to contribute to the ability of hPXR to respond to compounds of varying size and shape. Here, we describe an in silico method that allowed the identification of nine novel hPXR agonists. We further characterize the compound 1-(2-chlorophenyl)-N-[1-(1-phenylethyl)-1H-benzimidazol-5-yl]methanesulfonamide (C2BA-4), a methanesulfonamide that activates PXR specifically and more potently than does the reference compound 4-[2,2-bis(diethoxyphosphoryl)ethenyl]-2,6-ditert-butyl-phenol (SR12813) in our stable cell line expressing a Gal4-PXR and a GAL4 driven luciferase reporter gene. Furthermore treatment of primary human hepatocytes with C2BA-4 results in a marked induction of the mRNA expression of hPXR target genes, such as cytochromes P450 3A4 and 2B6. Finally, C2BA-4 is also able to induce hPXR-mediated in vivo luciferase expression in HGPXR stable bioluminescent cells implanted in mice. The study suggests new directions for the rational design of selective hPXR agonists and antagonists.
Collapse
Affiliation(s)
- Géraldine Lemaire
- Institut National de la Santé et de la Recherche Médicale (INSERM) U824, Montpellier, Université Montpellier, Montpellier, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Biggs JS, Wan J, Cutler NS, Hakkola J, Uusimäki P, Raunio H, Yost GS. Transcription factor binding to a putative double E-box motif represses CYP3A4 expression in human lung cells. Mol Pharmacol 2007; 72:514-25. [PMID: 17548528 DOI: 10.1124/mol.106.033795] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Two vital enzymes of the CYP3A subfamily, CYP3A4 and CYP3A5, are differentially expressed in the human lung. However, the molecular mechanisms that regulate tissue-selective expression of the genes are poorly understood. The ability of the 5' upstream promoter region of these two genes to drive luciferase reporter activities in human lung A549 cells was dramatically different. The CYP3A5 promoter region activated luciferase gene expression by 10-fold over the promoterless construct, whereas the CYP3A4 promoter did not drive expression. Sequence comparisons of the promoters identified a 57-base pair insertion in the CYP3A4 promoter region (-71 to -127) that was absent in the CYP3A5 promoter. Deletion of the 57-bp motif from CYP3A4 or insertion into the CYP3A5 promoter, showed that this motif represses CYP3A4 expression in lung. EMSA analysis using nuclear extracts from either A549 cells or human lung tissues showed two specific protein/DNA complexes formed with the (32)P-labeled CYP3A4 57-bp oligonucleotide. EMSA analyses identified two E-box motifs as the minimal specific cis-elements. Supershift assays with antibodies directed against known double- or single-E-box binding factors (TAL1, deltaEF1, E2A, HEB, etc.) failed to identify this factor as a previously characterized trans-acting double E-box binding protein. These results demonstrated that the 5'-upstream region of CYP3A4 contains an active putative double E-box repressor motif, not present in the 5'-upstream region of the CYP3A5 gene, that attenuates CYP3A4 expression in the human lung. We believe that this is the first documented case in which a cytochrome P450 gene is actively repressed in a tissue-specific manner.
Collapse
Affiliation(s)
- Jason S Biggs
- Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112-5820, USA
| | | | | | | | | | | | | |
Collapse
|
50
|
Lim YP, Huang JD. Pregnane X receptor polymorphism affects CYP3A4 induction via a ligand-dependent interaction with steroid receptor coactivator-1. Pharmacogenet Genomics 2007; 17:369-82. [PMID: 17429319 DOI: 10.1097/fpc.0b013e32803e40d7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND The human pregnane X receptor is a ligand-dependent transcription factor that plays critical roles in regulating detoxification genes such as CYP3A4 by recruiting transcriptional coactivators such as steroid receptor coactivator-1 in a ligand-dependent manner. In a previous study (Pharmacogenetics and Genomics 2005, 15: 337-341), we reported a novel pregnane X receptor single nucleotide polymorphism, Q158K, which impaired transactivation of CYP3A4. METHODS AND RESULTS By using DNA affinity precipitation assay and electrophoretic mobility shift assay, we have now shown that Q158K does not alter the binding affinity of pregnane X receptor for the CYP3A4 promoter. Instead, as shown using a mammalian two-hybrid assay, it decreased the interaction of pregnane X receptor with steroid receptor coactivator-1 in the presence of rifampin, clotrimazole, paclitaxel, or nifedipine but not in their absence. Rifampin treatment markedly increased pregnane X receptor protein in the wild-type pregnane X receptor-transfected cells as shown by coimmunoprecipitation but not in Q158K pregnane X receptor-transfected cells. The impaired transactivation of the CYP3A4 promoter was reversed by transfecting steroid receptor coactivator-1 expression plasmids. An additional nine pregnane X receptor variants were isolated and selected by random mutagenesis. Mutations Q158, W223, F257, I346, and L424 also reduced CYP3A4 transactivation and interaction in mammalian two-hybrid assays only in the presence of ligands. Although Q158K did not greatly affect the interaction of pregnane X receptor to silencing mediator of retinoid and thyroid hormone receptor, pregnane X receptor-silencing mediator of retinoid and thyroid hormone receptor interaction was impaired in the F257L and I346T variants with or without the presence of pregnane X receptor ligands. CONCLUSION Our data indicate that the impaired induction by the Q158K variant is probably due to defective steroid receptor coactivator-1 interaction in the presence of a pregnane X receptor ligand. As the whole ligand binding domain of pregnane X receptor is required for the interaction with steroid receptor coactivator-1, we propose that, not only the Q158K variant found in Chinese, but also in native pregnane X receptor variants in other ethnic groups (D163G, A370T, R381W, and I403V) affect CYP3A4 induction by altering steroid receptor coactivator-1 recruitment.
Collapse
Affiliation(s)
- Yun-Ping Lim
- Institute of Basic Medical Sciences, Department of Pharmacology, Medical College, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan
| | | |
Collapse
|