1
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Nilles J, Weiss J, Masin M, Tuffs C, Strowitzki MJ, Haefeli WE, Ruez S, Theile D. The differences in drug disposition gene induction by rifampicin and rifabutin are unlikely due to different effects on important pregnane X receptor (NR1I2) splice variants. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:2485-2496. [PMID: 37851058 PMCID: PMC10933196 DOI: 10.1007/s00210-023-02768-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/02/2023] [Indexed: 10/19/2023]
Abstract
Rifampicin and rifabutin can activate the pregnane X receptor (PXR, NR1I2), thereby inducing pharmacokinetically important genes/proteins and reducing exposure to co-administered drugs. Because induction effects vary considerably between these antibiotics, differences could be due to unequal rifamycin-induced activation or tissue expression of the three major NR1I2 splice variants, PXR.1 (NM_003889), PXR.2 (NM_022002), and PXR.3 (NM_033013). Consequently, PXR activation (PXR reporter gene assays) and mRNA expression levels of total NR1I2, PXR.1, PXR.2, and PXR.3 were investigated by polymerase chain reaction in colon and liver samples from eleven surgical patients, in LS180 cells, and primary human hepatocytes. Compared to the colon, total NR1I2 mRNA expression was higher in the liver. Both tissues showed similar expression levels of PXR.1 and PXR.3, respectively. PXR.2 was not quantifiable in the colon samples. Rifampicin and rifabutin similarly enhanced PXR.1 and PXR.2 activity when transfected into LS180 cells, while PXR.3 could not be activated. In LS180 cells, rifampicin (10 μM) reduced total NR1I2 and PXR.3 expression 2-fold after 24 h, while rifabutin (10 μM) increased total NR1I2, PXR.1, PXR.2, and PXR.3 mRNA by approx. 50% after 96-h exposure. In primary human hepatocytes, rifampicin (10 μM) suppressed total NR1I2, PXR.1, and PXR.3 after 48-h exposure, and rifabutin (10 μM) had no significant impact on total NR1I2 or any of the splice variants studied. In conclusion, both antibiotics activated the studied PXR splice variants similarly but modified their expression differently. While rifampicin can suppress mRNA of PXR forms, rifabutin rather increases their expression levels.
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Affiliation(s)
- Julie Nilles
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- Boehringer Ingelheim Pharma GmbH & Co, KG, Birkendorfer Str. 65, 88397, Biberach an der Riss, Germany
| | - Johanna Weiss
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Martin Masin
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Christopher Tuffs
- Departments of General, Visceral, and Transplantation Surgery, Heidelberg University Hospital, Im Neuenheimer Feld 420, 69120, Heidelberg, Germany
| | - Moritz J Strowitzki
- Departments of General, Visceral, and Transplantation Surgery, Heidelberg University Hospital, Im Neuenheimer Feld 420, 69120, Heidelberg, Germany
| | - Walter E Haefeli
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Stephanie Ruez
- Boehringer Ingelheim Pharma GmbH & Co, KG, Birkendorfer Str. 65, 88397, Biberach an der Riss, Germany
| | - Dirk Theile
- Department of Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany.
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2
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Dvořák Z, Li H, Mani S. Microbial Metabolites as Ligands to Xenobiotic Receptors: Chemical Mimicry as Potential Drugs of the Future. Drug Metab Dispos 2023; 51:219-227. [PMID: 36184080 PMCID: PMC9900867 DOI: 10.1124/dmd.122.000860] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 08/28/2022] [Accepted: 09/19/2022] [Indexed: 01/31/2023] Open
Abstract
Xenobiotic receptors, such as the pregnane X receptor, regulate multiple host physiologic pathways including xenobiotic metabolism, certain aspects of cellular metabolism, and innate immunity. These ligand-dependent nuclear factors regulate gene expression via genomic recognition of specific promoters and transcriptional activation of the gene. Natural or endogenous ligands are not commonly associated with this class of receptors; however, since these receptors are expressed in a cell-type specific manner in the liver and intestines, there has been significant recent effort to characterize microbially derived metabolites as ligands for these receptors. In general, these metabolites are thought to be weak micromolar affinity ligands. This journal anniversary minireview focuses on recent efforts to derive potentially nontoxic microbial metabolite chemical mimics that could one day be developed as drugs combating xenobiotic receptor-modifying pathophysiology. The review will include our perspective on the field and recommend certain directions for future research. SIGNIFICANCE STATEMENT: Xenobiotic receptors (XRs) regulate host drug metabolism, cellular metabolism, and immunity. Their presence in host intestines allows them to function not only as xenosensors but also as a response to the complex metabolic environment present in the intestines. Specifically, this review focuses on describing microbial metabolite-XR interactions and the translation of these findings toward discovery of novel chemical mimics as potential drugs of the future for diseases such as inflammatory bowel disease.
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Affiliation(s)
- Zdeněk Dvořák
- Department of Cell Biology and Genetics, Palacký University, Olomouc, Czech Republic (Z.D.); Departments of Medicine (H.L., S.M.), Molecular Pharmacology (S.M.), and Genetics (S.M.), Albert Einstein College of Medicine, Bronx, New York, USA
| | - Hao Li
- Department of Cell Biology and Genetics, Palacký University, Olomouc, Czech Republic (Z.D.); Departments of Medicine (H.L., S.M.), Molecular Pharmacology (S.M.), and Genetics (S.M.), Albert Einstein College of Medicine, Bronx, New York, USA
| | - Sridhar Mani
- Department of Cell Biology and Genetics, Palacký University, Olomouc, Czech Republic (Z.D.); Departments of Medicine (H.L., S.M.), Molecular Pharmacology (S.M.), and Genetics (S.M.), Albert Einstein College of Medicine, Bronx, New York, USA
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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.
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Boutot ME, Whitcomb BW, Abdelouahab N, Baccarelli AA, Boivin A, Caku A, Gillet V, Martinez G, Pasquier JC, Zhu J, Takser L, St-Cyr L, Suvorov A. In Utero Exposure to Persistent Organic Pollutants and Childhood Lipid Levels. Metabolites 2021; 11:657. [PMID: 34677372 PMCID: PMC8540619 DOI: 10.3390/metabo11100657] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/21/2021] [Accepted: 09/24/2021] [Indexed: 12/15/2022] Open
Abstract
Animal studies have shown that developmental exposures to polybrominated diphenyl ethers (PBDE) permanently affect blood/liver balance of lipids. No human study has evaluated associations between in utero exposures to persistent organic pollutants (POPs) and later life lipid metabolism. In this pilot, maternal plasma levels of PBDEs (BDE-47, BDE-99, BDE-100, and BDE-153) and polychlorinated biphenyls (PCB-138, PCB-153, and PCB-180) were determined at delivery in participants of GESTation and Environment (GESTE) cohort. Total cholesterol (TCh), triglycerides (TG), low- and high-density lipoproteins (LDL-C and HDL-C), total lipids (TL), and PBDEs were determined in serum of 147 children at ages 6-7. General linear regression was used to estimate the relationship between maternal POPs and child lipid levels with adjustment for potential confounders, and adjustment for childhood POPs. In utero BDE-99 was associated with lower childhood levels of TG (p = 0.003), and non-significantly with HDL-C (p = 0.06) and TL (p = 0.07). Maternal PCB-138 was associated with lower childhood levels of TG (p = 0.04), LDL-C (p = 0.04), and TL (p = 0.02). Our data indicate that in utero exposures to POPs may be associated with long lasting decrease in circulating lipids in children, suggesting increased lipid accumulation in the liver, a mechanism involved in NAFLD development, consistent with previously reported animal data.
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Affiliation(s)
- Maegan E. Boutot
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, MA 01003, USA; (M.E.B.); (B.W.W.)
| | - Brian W. Whitcomb
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, MA 01003, USA; (M.E.B.); (B.W.W.)
| | - Nadia Abdelouahab
- Department of Obstetrics and Gynecology, Faculty of Medicine and Health Sciences, Sherbrooke University, Sherbrooke, QC J1H 5N4, Canada; (N.A.); (J.-C.P.)
| | - Andrea A. Baccarelli
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA;
| | - Amélie Boivin
- Department of Pediatrics, Faculty of Medicine and Health Sciences, Sherbrooke University, Sherbrooke, QC J1H 5N4, Canada; (A.B.); (V.G.); (L.S.-C.)
| | - Artuela Caku
- Department of Biochemistry and Functional Genomics, Faculty of Medicine and Health Sciences, Sherbrooke University, Sherbrooke, QC J1H 5N4, Canada;
| | - Virginie Gillet
- Department of Pediatrics, Faculty of Medicine and Health Sciences, Sherbrooke University, Sherbrooke, QC J1H 5N4, Canada; (A.B.); (V.G.); (L.S.-C.)
| | - Guillaume Martinez
- Department of Chemistry, Faculty of Sciences, Sherbrooke, QC J1K 2R1, Canada;
| | - Jean-Charles Pasquier
- Department of Obstetrics and Gynecology, Faculty of Medicine and Health Sciences, Sherbrooke University, Sherbrooke, QC J1H 5N4, Canada; (N.A.); (J.-C.P.)
| | - Jiping Zhu
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON K1A 0K9, Canada;
| | - Larissa Takser
- Department of Pediatrics & Department of Psychiatry, Faculty of Medicine and Health Sciences, Sherbrooke University, Sherbrooke, QC J1H 5N4, Canada;
| | - Lindsay St-Cyr
- Department of Pediatrics, Faculty of Medicine and Health Sciences, Sherbrooke University, Sherbrooke, QC J1H 5N4, Canada; (A.B.); (V.G.); (L.S.-C.)
| | - Alexander Suvorov
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, MA 01003, USA; (M.E.B.); (B.W.W.)
- Department of Environmental Health Sciences, School of Public Health and Health Sciences, University of Massachusetts Amherst, Amherst, MA 01003, USA
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Mukha A, Kalkhoven E, van Mil SWC. Splice variants of metabolic nuclear receptors: Relevance for metabolic disease and therapeutic targeting. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166183. [PMID: 34058349 DOI: 10.1016/j.bbadis.2021.166183] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/17/2021] [Accepted: 05/25/2021] [Indexed: 12/13/2022]
Abstract
Metabolic nuclear receptors are ligand-activated transcription factors which control a wide range of metabolic processes and signaling pathways in response to nutrients and xenobiotics. Targeting these NRs is at the forefront of our endeavours to generate novel treatment options for diabetes, metabolic syndrome and fatty liver disease. Numerous splice variants have been described for these metabolic receptors. Structural changes, as a result of alternative splicing, lead to functional differences among NR isoforms, resulting in the regulation of different metabolic pathways by these NR splice variants. In this review, we describe known splice variants of FXR, LXRs, PXR, RXR, LRH-1, CAR and PPARs. We discuss their structure and functions, and elaborate on the regulation of splice variant abundance by nutritional signals. We conclude that NR splice variants pose an intriguing new layer of complexity in metabolic signaling, which needs to be taken into account in the development of treatment strategies for metabolic diseases.
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Affiliation(s)
- Anna Mukha
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands
| | - Eric Kalkhoven
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands
| | - Saskia W C van Mil
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands.
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6
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Lin YS, Thummel KE, Thompson BD, Totah RA, Cho CW. Sources of Interindividual Variability. Methods Mol Biol 2021; 2342:481-550. [PMID: 34272705 DOI: 10.1007/978-1-0716-1554-6_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The efficacy, safety, and tolerability of drugs are dependent on numerous factors that influence their disposition. A dose that is efficacious and safe for one individual may result in sub-therapeutic or toxic blood concentrations in others. A significant source of this variability in drug response is drug metabolism, where differences in presystemic and systemic biotransformation efficiency result in variable degrees of systemic exposure (e.g., AUC, Cmax, and/or Cmin) following administration of a fixed dose.Interindividual differences in drug biotransformation have been studied extensively. It is recognized that both intrinsic factors (e.g., genetics, age, sex, and disease states) and extrinsic factors (e.g., diet , chemical exposures from the environment, and the microbiome) play a significant role. For drug-metabolizing enzymes, genetic variation can result in the complete absence or enhanced expression of a functional enzyme. In addition, upregulation and downregulation of gene expression, in response to an altered cellular environment, can achieve the same range of metabolic function (phenotype), but often in a less predictable and time-dependent manner. Understanding the mechanistic basis for variability in drug disposition and response is essential if we are to move beyond the era of empirical, trial-and-error dose selection and into an age of personalized medicine that will improve outcomes in maintaining health and treating disease.
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Affiliation(s)
- Yvonne S Lin
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA.
| | - Kenneth E Thummel
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA
| | - Brice D Thompson
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA
| | - Rheem A Totah
- Department of Medicinal Chemistry, University of Washington, Seattle, WA, USA
| | - Christi W Cho
- Department of Medicinal Chemistry, University of Washington, Seattle, WA, USA
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7
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Salanga MC, Brun NR, Francolini RD, Stegeman JJ, Goldstone JV. CRISPR-Cas9-Mutated Pregnane X Receptor (pxr) Retains Pregnenolone-induced Expression of cyp3a65 in Zebrafish (Danio rerio) Larvae. Toxicol Sci 2020; 174:51-62. [PMID: 31868891 PMCID: PMC7043230 DOI: 10.1093/toxsci/kfz246] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pregnane X receptor (PXR; NR1I2) is a nuclear receptor that regulates transcriptional responses to drug or xenobiotic exposure, including induction of CYP3A transcription, in many vertebrate species. PXR is activated by a wide range of ligands that differ across species, making functional studies on its role in the chemical defensome most relevant when approached in a species-specific manner. Knockout studies in mammals have shown a requirement for PXR in ligand-dependent activation of CYP3A expression or reporter gene activity. Morpholino knockdown of Pxr in zebrafish indicated a similar requirement. Here, we report on the generation of 2 zebrafish lines each carrying a heritable deletion in the pxr coding region, predicted to result in loss of a functional gene product. To our surprise, larvae homozygous for either of the pxr mutant alleles retain their ability to induce cyp3a65 mRNA expression following exposure to the established zebrafish Pxr ligand, pregnenolone. Thus, zebrafish carrying pxr alleles with deletions in either the DNA binding or the ligand-binding domains did not yield a loss-of-function phenotype, suggesting that a compensatory mechanism is responsible for cyp3a65 induction. Alternative possibilities are that Pxr is not required for the induction of selected genes, or that truncated yet functional mutant Pxr is sufficient for the downstream transcriptional effects. It is crucial that we develop a better understanding for the role of Pxr in this important biomedical test species. This study highlights the potential for compensatory mechanisms to avoid deleterious effects arising from gene mutations.
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Affiliation(s)
- Matthew C Salanga
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
| | - Nadja R Brun
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
| | - Rene D Francolini
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
| | - John J Stegeman
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
| | - Jared V Goldstone
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
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8
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Annalora AJ, Marcus CB, Iversen PL. Alternative Splicing in the Nuclear Receptor Superfamily Expands Gene Function to Refine Endo-Xenobiotic Metabolism. Drug Metab Dispos 2020; 48:272-287. [DOI: 10.1124/dmd.119.089102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/31/2019] [Indexed: 12/20/2022] Open
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9
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Duszka K, Wahli W. Enteric Microbiota⁻Gut⁻Brain Axis from the Perspective of Nuclear Receptors. Int J Mol Sci 2018; 19:ijms19082210. [PMID: 30060580 PMCID: PMC6121494 DOI: 10.3390/ijms19082210] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/18/2018] [Accepted: 07/23/2018] [Indexed: 12/12/2022] Open
Abstract
Nuclear receptors (NRs) play a key role in regulating virtually all body functions, thus maintaining a healthy operating body with all its complex systems. Recently, gut microbiota emerged as major factor contributing to the health of the whole organism. Enteric bacteria have multiple ways to influence their host and several of them involve communication with the brain. Mounting evidence of cooperation between gut flora and NRs is already available. However, the full potential of the microbiota interconnection with NRs remains to be uncovered. Herewith, we present the current state of knowledge on the multifaceted roles of NRs in the enteric microbiota–gut–brain axis.
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Affiliation(s)
- Kalina Duszka
- Department of Nutritional Sciences, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
| | - Walter Wahli
- Lee Kong Chian School of Medicine, Nanyang Technological, 11 Mandalay Road, Singapore 308232, Singapore.
- Center for Integrative Genomics, University of Lausanne, Génopode, CH-1015 Lausanne, Switzerland.
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10
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Marques C, Roberto VP, Granadeiro L, Trindade M, Gavaia PJ, Laizé V, Cancela ML, Fernández I. The xenobiotic sensor PXR in a marine flatfish species (Solea senegalensis): Gene expression patterns and its regulation under different physiological conditions. MARINE ENVIRONMENTAL RESEARCH 2017; 130:187-199. [PMID: 28768576 DOI: 10.1016/j.marenvres.2017.07.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 06/06/2017] [Accepted: 07/21/2017] [Indexed: 06/07/2023]
Abstract
The pregnane X receptor (PXR) is a nuclear receptor belonging to the NR1I sub-family and a known master regulator of xenobiotic metabolism. New roles have been recently proposed in mammals through its activation by vitamin K (VK) such as regulation of glucose metabolism, bone homeostasis, reproduction, neuronal development and cognitive capacities. In marine fish species little is known about PXR and its potential roles. Here, expression patterns of pxr transcripts and conservation of protein domains were determined in the Senegalese sole (Solea senegalensis), a marine flatfish model species in aquatic ecotoxicology. In addition to a full coding sequence transcript (sspxr1), two variants lacking DNA and/or ligand binding domains (sspxr2 and sspxr3) were also identified. The expression of sspxr1 during early development and in adult tissues was ubiquitous, but highest levels were observed in liver, intestine and skin. Expression was also detected by in situ hybridization in chondrocytes and cells from the granular and inner nuclear layers in three month old fish. Finally, sspxr1 expression was shown to be differentially regulated under physiological conditions related with fasting, VK and warfarin metabolism. The present work provides new and basic knowledge regarding pxr sequence and expression patterns in a marine flatfish species to unveil the potential impact of xenobiotics on marine fish physiology, and will allow a better and more ecosystemic environmental risk assessment of different pollutants over the marine environments with the development of reporter assays using PXR sequences from evolutionary distantly marine species (such as vertebrate and invertebrate marine species).
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Affiliation(s)
- Carlos Marques
- Centro de Ciências do Mar do Algarve (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Vânia P Roberto
- Centro de Ciências do Mar do Algarve (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Luís Granadeiro
- Centro de Ciências do Mar do Algarve (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Marlene Trindade
- Centro de Ciências do Mar do Algarve (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Paulo J Gavaia
- Centro de Ciências do Mar do Algarve (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Departamento de Ciências Biomédicas e Medicina (DCBM), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Vincent Laizé
- Centro de Ciências do Mar do Algarve (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - M Leonor Cancela
- Centro de Ciências do Mar do Algarve (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Departamento de Ciências Biomédicas e Medicina (DCBM), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Algarve Biomedical Center (ABC), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Ignacio Fernández
- Centro de Ciências do Mar do Algarve (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
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11
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Bakshi K, Ranjitha B, Dubey S, Jagannadham J, Jaiswal B, Gupta A. Novel complex of HAT protein TIP60 and nuclear receptor PXR promotes cell migration and adhesion. Sci Rep 2017. [PMID: 28623334 PMCID: PMC5473911 DOI: 10.1038/s41598-017-03783-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PXR is a member of nuclear receptor superfamily and a well-characterized mediator of xenobiotic metabolism. The classical mode of PXR activation involves its binding to appropriate ligand and subsequent heterodimerization with its partner RXR. However, various factors such as post-translational modifications and crosstalk with different cellular factors may also regulate the functional dynamics and behavior of PXR. In the present study, we have identified that TIP60, an essential lysine acetyltransferase protein interacts with unliganded PXR and together this complex promotes cell migration & adhesion. TIP60 utilizes its NR Box to interact with LBD region of PXR and acetylates PXR at lysine 170 to induce its intranuclear reorganization. Also, RXR is not required for TIP60-PXR complex formation and this complex does not induce ligand-dependent PXR target gene transactivation. Interestingly, we observed that PXR augments the catalytic activity of TIP60 for histones. This is the first report demonstrating the exclusive interaction of TIP60 with PXR and uncovers a potential role for the TIP60-PXR complex in cell migration and adhesion.
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Affiliation(s)
- Karishma Bakshi
- Department of Life Sciences, Shiv Nadar University, Greater Noida, India
| | - B Ranjitha
- Department of Life Sciences, Shiv Nadar University, Greater Noida, India
| | - Shraddha Dubey
- Department of Life Sciences, Shiv Nadar University, Greater Noida, India
| | - Jaisri Jagannadham
- Department of Life Sciences, Shiv Nadar University, Greater Noida, India
| | - Bharti Jaiswal
- Department of Life Sciences, Shiv Nadar University, Greater Noida, India
| | - Ashish Gupta
- Department of Life Sciences, Shiv Nadar University, Greater Noida, India.
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12
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Brewer CT, Chen T. PXR variants: the impact on drug metabolism and therapeutic responses. Acta Pharm Sin B 2016; 6:441-449. [PMID: 27709012 PMCID: PMC5045535 DOI: 10.1016/j.apsb.2016.07.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 04/21/2016] [Accepted: 05/04/2016] [Indexed: 01/30/2023] Open
Abstract
The pregnane X receptor (PXR) plays an important and diverse role in mediating xenobiotic induction of drug-metabolizing enzymes and transporters. Several protein isoforms of PXR exist, and they have differential transcriptional activity upon target genes; transcript variants 3 (PXR3) and 4 (PXR4) do not induce target gene expression, whereas transcript variants 1 (PXR1) and 2 (PXR2) respond to agonist by activating target gene expression. PXR protein variants also display differences in protein-protein interactions; PXR1 interacts with p53, whereas PXR3 does not. Furthermore, the transcript variants of PXR that encode these protein isoforms are differentially regulated by methylation and deletions in the respective promoters of the variants, and their expression differs in various human cancers and also in cancerous tissue compared to adjacent normal tissues. PXR1 and PXR4 mRNA are downregulated by methylation in cancerous tissue and have divergent effects on cellular proliferation when ectopically overexpressed. Additional detailed and comparative mechanistic studies are required to predict the effect of PXR transcript variant expression on carcinogenesis, therapeutic response, and the development of toxicity.
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Key Words
- AF, activating function
- BAMCA, bacterial artificial chromosome array–based methylated CpG island amplification
- CYP, cytochrome P450
- Drug metabolism
- GST, glutathione S-transferase
- MDR, multidrug resistance protein
- NHR, nuclear hormone receptor
- P-gp, P-glycoprotein
- PXR1, PXR transcript variant 1 (434 residues)
- PXR2, transcript variant 2 (473 residues)
- PXR3, transcript variant 3 (397 residues)
- PXR4, transcript variant 4 (322 residues;AK122990)
- Pregnane X receptor
- RACE, 5′ rapid amplification of cDNA ends
- Therapeutic responses
- Toxicity
- Transcript variants
- UGT, UDP-glucuronosyltransferase
- UTR, untranslated region
- shRNA, short hairpin RNA
- siRNA, small interfering RNA
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Affiliation(s)
- C. Trent Brewer
- Department of Chemical Biology and Therapeutics, St. Jude Children′s Research Hospital, Memphis, TN 38105, USA
- Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children′s Research Hospital, Memphis, TN 38105, USA
- Integrated Biomedical Sciences Program, University of Tennessee Health Science Center, Memphis, TN 38163, USA
- Corresponding author at: Department of Chemical Biology and Therapeutics, St. Jude Children′s Research Hospital, Mail Stop #1000, 262 Danny Thomas Place, Memphis, TN 38105, USA. Tel.: +1 901 595 5937; fax: +1 901 595 5715.Department of Chemical Biology and Therapeutics, St. Jude Children′s Research Hospital, Mail Stop #1000, 262 Danny Thomas PlaceMemphisTN38105USA
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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: 46] [Impact Index Per Article: 5.8] [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.
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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
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14
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Zeng C, Matsuda K, Jia WH, Chang J, Kweon SS, Xiang YB, Shin A, Jee SH, Kim DH, Zhang B, Cai Q, Guo X, Long J, Wang N, Courtney R, Pan ZZ, Wu C, Takahashi A, Shin MH, Matsuo K, Matsuda F, Gao YT, Oh JH, Kim S, Jung KJ, Ahn YO, Ren Z, Li HL, Wu J, Shi J, Wen W, Yang G, Li B, Ji BT, Brenner H, Schoen RE, Küry S, Gruber SB, Schumacher FR, Stenzel SL, Casey G, Hopper JL, Jenkins MA, Kim HR, Jeong JY, Park JW, Tajima K, Cho SH, Kubo M, Shu XO, Lin D, Zeng YX, Zheng W. Identification of Susceptibility Loci and Genes for Colorectal Cancer Risk. Gastroenterology 2016; 150:1633-1645. [PMID: 26965516 PMCID: PMC4909543 DOI: 10.1053/j.gastro.2016.02.076] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 02/22/2016] [Accepted: 02/29/2016] [Indexed: 01/24/2023]
Abstract
BACKGROUND & AIMS Known genetic factors explain only a small fraction of genetic variation in colorectal cancer (CRC). We conducted a genome-wide association study to identify risk loci for CRC. METHODS This discovery stage included 8027 cases and 22,577 controls of East-Asian ancestry. Promising variants were evaluated in studies including as many as 11,044 cases and 12,047 controls. Tumor-adjacent normal tissues from 188 patients were analyzed to evaluate correlations of risk variants with expression levels of nearby genes. Potential functionality of risk variants were evaluated using public genomic and epigenomic databases. RESULTS We identified 4 loci associated with CRC risk; P values for the most significant variant in each locus ranged from 3.92 × 10(-8) to 1.24 × 10(-12): 6p21.1 (rs4711689), 8q23.3 (rs2450115, rs6469656), 10q24.3 (rs4919687), and 12p13.3 (rs11064437). We also identified 2 risk variants at loci previously associated with CRC: 10q25.2 (rs10506868) and 20q13.3 (rs6061231). These risk variants, conferring an approximate 10%-18% increase in risk per allele, are located either inside or near protein-coding genes that include transcription factor EB (lysosome biogenesis and autophagy), eukaryotic translation initiation factor 3, subunit H (initiation of translation), cytochrome P450, family 17, subfamily A, polypeptide 1 (steroidogenesis), splA/ryanodine receptor domain and SOCS box containing 2 (proteasome degradation), and ribosomal protein S2 (ribosome biogenesis). Gene expression analyses showed a significant association (P < .05) for rs4711689 with transcription factor EB, rs6469656 with eukaryotic translation initiation factor 3, subunit H, rs11064437 with splA/ryanodine receptor domain and SOCS box containing 2, and rs6061231 with ribosomal protein S2. CONCLUSIONS We identified susceptibility loci and genes associated with CRC risk, linking CRC predisposition to steroid hormone, protein synthesis and degradation, and autophagy pathways and providing added insight into the mechanism of CRC pathogenesis.
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Affiliation(s)
- Chenjie Zeng
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Koichi Matsuda
- Laboratory of Genome Technology, Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Wei-Hua Jia
- State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China
| | - Jiang Chang
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Sun-Seog Kweon
- Department of Preventive Medicine, Chonnam National University Medical School, Gwangju, South Korea; Jeonnam Regional Cancer Center, Chonnam National University Hwasun Hospital, Hwasun, South Korea
| | - Yong-Bing Xiang
- Department of Epidemiology, Shanghai Cancer Institute, Shanghai, China
| | - Aesun Shin
- Molecular Epidemiology Branch, National Cancer Center, Goyang-si, South Korea; Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, South Korea
| | - Sun Ha Jee
- Institute for Health Promotion, Department of Epidemiology and Health Promotion, Graduate School of Public Health, Yonsei University, Seoul, South Korea
| | - Dong-Hyun Kim
- Department of Social and Preventive Medicine, Hallym University College of Medicine, Okcheon-dong, South Korea
| | - Ben Zhang
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Qiuyin Cai
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Xingyi Guo
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jirong Long
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Nan Wang
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee; General Department, Tangdu Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Regina Courtney
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Zhi-Zhong Pan
- State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China
| | - Chen Wu
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | | | - Min-Ho Shin
- Department of Preventive Medicine, Chonnam National University Medical School, Gwangju, South Korea
| | - Keitaro Matsuo
- Division of Molecular Medicine, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Fumihiko Matsuda
- Center for Genomic Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yu-Tang Gao
- Department of Epidemiology, Shanghai Cancer Institute, Shanghai, China
| | - Jae Hwan Oh
- Center for Colorectal Cancer, National Cancer Center, Goyang-si, South Korea
| | - Soriul Kim
- Institute for Health Promotion, Department of Epidemiology and Health Promotion, Graduate School of Public Health, Yonsei University, Seoul, South Korea
| | - Keum Ji Jung
- Institute for Health Promotion, Department of Epidemiology and Health Promotion, Graduate School of Public Health, Yonsei University, Seoul, South Korea
| | - Yoon-Ok Ahn
- Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, South Korea
| | - Zefang Ren
- School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Hong-Lan Li
- Department of Epidemiology, Shanghai Cancer Institute, Shanghai, China
| | - Jie Wu
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jiajun Shi
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Wanqing Wen
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Gong Yang
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Bingshan Li
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Bu-Tian Ji
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland
| | - Hermann Brenner
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany; Division of Preventive Oncology, National Center for Tumor Diseases (NCT) and German Cancer Research Center (DKFZ), Heidelberg, Germany; German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Robert E Schoen
- Department of Medicine and Epidemiology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Sébastien Küry
- CHU Nantes, Service de Génétique Médicale, Nantes, France
| | - Stephen B Gruber
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California
| | - Fredrick R Schumacher
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California
| | - Stephanie L Stenzel
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California
| | - Graham Casey
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California
| | - John L Hopper
- Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Mark A Jenkins
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Hyeong-Rok Kim
- Department of Surgery, Chonnam National University Medical School, Gwangju, South Korea
| | - Jin-Young Jeong
- Department of Social and Preventive Medicine, Hallym University College of Medicine, Okcheon-dong, South Korea
| | - Ji Won Park
- Center for Colorectal Cancer, National Cancer Center, Goyang-si, South Korea; Department of Surgery, Seoul National University Hospital, Seoul, South Korea
| | - Kazuo Tajima
- Department of Public Health and Occupational Medicine, Mie University Graduate School of Medicine, Mie, Japan
| | - Sang-Hee Cho
- Department of Hemato-oncology, Chonnam National University Medical School, Gwangju, South Korea
| | - Michiaki Kubo
- RIKEN Center for Integrative Medical Sciences, Kanagawa, Japan
| | - Xiao-Ou Shu
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Dongxin Lin
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yi-Xin Zeng
- State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, Guangzhou, China
| | - Wei Zheng
- Division of Epidemiology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, Tennessee.
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15
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Abstract
CYP3A ranks among the most abundant cytochrome P450 enzymes in the liver, playing a dominant role in metabolic elimination of clinically used drugs. A main member in CYP3A family, CYP3A4 expression and activity vary considerably among individuals, attributable to genetic and non-genetic factors, affecting drug dosage and efficacy. However, the extent of genetic influence has remained unclear. This review assesses current knowledge on the genetic factors influencing CYP3A4 activity. Coding region CYP3A4 polymorphisms are rare and account for only a small portion of inter-person variability in CYP3A metabolism. Except for the promoter allele CYP3A4*1B with ambiguous effect on expression, common CYP3A4 regulatory polymorphisms were thought to be lacking. Recent studies have identified a relatively common regulatory polymorphism, designated CYP3A4*22 with robust effects on hepatic CYP3A4 expression. Combining CYP3A4*22 with CYP3A5 alleles *1, *3 and *7 has promise as a biomarker predicting overall CYP3A activity. Also contributing to variable expression, the role of polymorphisms in transcription factors and microRNAs is discussed.
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Affiliation(s)
- Danxin Wang
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-614-292-7336; Fax: +1-614-292-7232
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16
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Zhuo W, Hu L, Lv J, Wang H, Zhou H, Fan L. Role of pregnane X receptor in chemotherapeutic treatment. Cancer Chemother Pharmacol 2014; 74:217-27. [PMID: 24889719 DOI: 10.1007/s00280-014-2494-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Accepted: 05/06/2014] [Indexed: 10/25/2022]
Abstract
Pregnane X receptor (PXR) is a member of the nuclear receptor superfamily that differently expresses not only in human normal tissues but also in numerous types of human cancers. PXR can be activated by many endogenous substances and exogenous chemicals, and thus affects chemotherapeutic effects and intervenes drug-drug interactions by regulating its target genes involving drug metabolism and transportation, cell proliferation and apoptosis, and modulating endobiotic homeostasis. Tissue and context-specific regulation of PXR contributes to diverse effects in the treatment for numerous cancers. Genetic variants of PXR lead to intra- and inter-individual differences in the expression and inducibility of PXR, resulting in different responses to chemotherapy in PXR-positive cancers. The purpose of this review is to summarize and discuss the role of PXR in the metabolism and clearance of anticancer drugs. It is also expected that this review will provide insights into PXR-mediated enhancement for chemotherapeutic treatment, prediction of drug-drug interactions and personalized medicine.
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Affiliation(s)
- Wei Zhuo
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha, 410008, People's Republic of China
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17
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Abstract
The efficacy, safety, and tolerability of drugs are dependent on numerous factors that influence their disposition. A dose that is efficacious and safe for one individual may result in sub-therapeutic or toxic blood concentrations in other individuals. A major source of this variability in drug response is drug metabolism, where differences in pre-systemic and systemic biotransformation efficiency result in variable degrees of systemic exposure (e.g., AUC, C max, and/or C min) following administration of a fixed dose.Interindividual differences in drug biotransformation have been studied extensively. It is well recognized that both intrinsic (such as genetics, age, sex, and disease states) and extrinsic (such as diet, chemical exposures from the environment, and even sunlight) factors play a significant role. For the family of cytochrome P450 enzymes, the most critical of the drug metabolizing enzymes, genetic variation can result in the complete absence or enhanced expression of a functional enzyme. In addition, up- and down-regulation of gene expression, in response to an altered cellular environment, can achieve the same range of metabolic function (phenotype), but often in a less reliably predictable and time-dependent manner. Understanding the mechanistic basis for drug disposition and response variability is essential if we are to move beyond the era of empirical, trial-and-error dose selection and into an age of personalized medicine that brings with it true improvements in health outcomes in the therapeutic treatment of disease.
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Affiliation(s)
- Kenneth E Thummel
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA
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18
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Gao L, He Y, Tang J, Yin J, Huang Z, Liu F, Ouyang D, Chen X, Zhang W, Liu Z, Zhou H. Genetic Variants of Pregnane X Receptor (PXR) and CYP2B6 Affect the Induction of Bupropion Hydroxylation by Sodium Ferulate. PLoS One 2013; 8:e62489. [PMID: 23840296 PMCID: PMC3686783 DOI: 10.1371/journal.pone.0062489] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 03/22/2013] [Indexed: 11/19/2022] Open
Abstract
UNLABELLED This study investigated the effects of pregnane X receptor (PXR/NR1I2) and CYP2B6 genetic variants on sodium ferulate (SF)-mediated induction of bupropion hydroxylation. The pharmacokinetics of bupropion and hydroxybupropion were evaluated after an oral dose of bupropion (150 mg) administered with and without SF pretreatment for 14 days in 33 healthy subjects. The area under the time-concentration curve (AUC) ratio of AUC_hyd (AUC(0-∞) of hydroxybupropion)/AUC_bup (AUC(0-∞) of bupropion) represents the CYP2B6 hydroxylation activity, which was significantly lower in CYP2B6*6 carriers (NR1I2 TGT noncarriers or carriers) than in noncarriers in both the basal and SF-induced states (p-value<0.05). AUC ratio and AUC_hyd of NR1I2 -24113AA variant were markedly lower than GA and GG genotypes (7.5±2.1 versus 14.5±3.3 and 20.6±1.1, and 8873±1431 versus 14,504±2218 and 17,586±1046) in the induced states. However, -24020(-)/(-) variant didn't show significant difference in the induction of CYP2B6 hydroxylation activity by SF compared with other -24020[GAGAAG]/(-) genotypes. NR1I2 TGT haplotype (-25385T+g.7635G+g.8055T) carriers exhibited a significantly decreased AUC ratio, compared with TGT noncarriers, in the basal states (7.6±1.0 versus 9.7±1.0), while this result wasn't observed in CYP2B6*6 noncarriers. Moreover, individuals with complete mutation-type [CYP2B6*6/*6+NR1I2 TGT+ -24113AA+ -24020 (-)/(-)] showed even lower percent difference of AUC ratio (8.7±1.2 versus 39.5±8.2) than those with complete wild-type. In conclusion, it is suggested that NR1I2 variants decrease the bupropion hydroxylation induced by SF treatment, particularly in CYP2B6*6 carriers. TRIAL REGISTRATION ChiCTR.org ChiCTR-TRC-11001285.
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Affiliation(s)
- Lichen Gao
- Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Hunan Key laboratory of Pharmacogenetics, Central South University, Changsha, Hunan, China
- Department of Pharmacy, Changsha Central Hospital, Changsha, Hunan, China
| | - Yijing He
- Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Hunan Key laboratory of Pharmacogenetics, Central South University, Changsha, Hunan, China
- Institute for Pharmacogenomics and Individualized Therapy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jie Tang
- Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Hunan Key laboratory of Pharmacogenetics, Central South University, Changsha, Hunan, China
| | - Jiye Yin
- Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Hunan Key laboratory of Pharmacogenetics, Central South University, Changsha, Hunan, China
| | - Zhengyu Huang
- Department of Pharmacy, Changsha Central Hospital, Changsha, Hunan, China
| | - Fangqun Liu
- Department of Pharmacy, Changsha Central Hospital, Changsha, Hunan, China
| | - Dongsheng Ouyang
- Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Hunan Key laboratory of Pharmacogenetics, Central South University, Changsha, Hunan, China
| | - Xiaoping Chen
- Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Hunan Key laboratory of Pharmacogenetics, Central South University, Changsha, Hunan, China
| | - Wei Zhang
- Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Hunan Key laboratory of Pharmacogenetics, Central South University, Changsha, Hunan, China
| | - Zhaoqian Liu
- Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Hunan Key laboratory of Pharmacogenetics, Central South University, Changsha, Hunan, China
| | - Honghao Zhou
- Pharmacogenetics Research Institute, Institute of Clinical Pharmacology, Hunan Key laboratory of Pharmacogenetics, Central South University, Changsha, Hunan, China
- * E-mail:
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19
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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.
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Affiliation(s)
- Ayesha Elias
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105-3678, USA
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20
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Kelemen O, Convertini P, Zhang Z, Wen Y, Shen M, Falaleeva M, Stamm S. Function of alternative splicing. Gene 2013; 514:1-30. [PMID: 22909801 PMCID: PMC5632952 DOI: 10.1016/j.gene.2012.07.083] [Citation(s) in RCA: 515] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 12/15/2022]
Abstract
Almost all polymerase II transcripts undergo alternative pre-mRNA splicing. Here, we review the functions of alternative splicing events that have been experimentally determined. The overall function of alternative splicing is to increase the diversity of mRNAs expressed from the genome. Alternative splicing changes proteins encoded by mRNAs, which has profound functional effects. Experimental analysis of these protein isoforms showed that alternative splicing regulates binding between proteins, between proteins and nucleic acids as well as between proteins and membranes. Alternative splicing regulates the localization of proteins, their enzymatic properties and their interaction with ligands. In most cases, changes caused by individual splicing isoforms are small. However, cells typically coordinate numerous changes in 'splicing programs', which can have strong effects on cell proliferation, cell survival and properties of the nervous system. Due to its widespread usage and molecular versatility, alternative splicing emerges as a central element in gene regulation that interferes with almost every biological function analyzed.
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Affiliation(s)
- Olga Kelemen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Paolo Convertini
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zhaiyi Zhang
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Yuan Wen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Manli Shen
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Marina Falaleeva
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States of America
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21
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Wallace BD, Redinbo MR. Xenobiotic-sensing nuclear receptors involved in drug metabolism: a structural perspective. Drug Metab Rev 2012; 45:79-100. [PMID: 23210723 DOI: 10.3109/03602532.2012.740049] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Xenobiotic compounds undergo a critical range of biotransformations performed by the phase I, II, and III drug-metabolizing enzymes. The oxidation, conjugation, and transportation of potentially harmful xenobiotic and endobiotic compounds achieved by these catalytic systems are significantly regulated, at the gene expression level, by members of the nuclear receptor (NR) family of ligand-modulated transcription factors. Activation of NRs by a variety of endo- and exogenous chemicals are elemental to induction and repression of drug-metabolism pathways. The master xenobiotic sensing NRs, the promiscuous pregnane X receptor and less-promiscuous constitutive androstane receptor are crucial to initial ligand recognition, jump-starting the metabolic process. Other receptors, including farnesoid X receptor, vitamin D receptor, hepatocyte nuclear factor 4 alpha, peroxisome proliferator activated receptor, glucocorticoid receptor, liver X receptor, and RAR-related orphan receptor, are not directly linked to promiscuous xenobiotic binding, but clearly play important roles in the modulation of metabolic gene expression. Crystallographic studies of the ligand-binding domains of nine NRs involved in drug metabolism provide key insights into ligand-based and constitutive activity, coregulator recruitment, and gene regulation. Structures of other, noncanonical transcription factors also shed light on secondary, but important, pathways of control. Pharmacological targeting of some of these nuclear and atypical receptors has been instituted as a means to treat metabolic and developmental disorders and provides a future avenue to be explored for other members of the xenobiotic-sensing NRs.
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Affiliation(s)
- Bret D Wallace
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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22
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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.
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Zheng XE, Wang Z, Liao MZ, Lin YS, Shuhart MC, Schuetz EG, Thummel KE. Human PXR-mediated induction of intestinal CYP3A4 attenuates 1α,25-dihydroxyvitamin D₃ function in human colon adenocarcinoma LS180 cells. Biochem Pharmacol 2012; 84:391-401. [PMID: 22562045 DOI: 10.1016/j.bcp.2012.04.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 04/25/2012] [Accepted: 04/27/2012] [Indexed: 12/12/2022]
Abstract
Oxidative catabolism of 1α,25-dihydroxyvitamin D(3) [1α,25(OH)(2)D(3)] is mediated by either CYP24A1 or CYP3A4. In this paper, we tested whether induction of CYP3A4 in the LS180 intestinal cell model enhances clearance of 1α,25(OH)(2)D(3) and blunts its hormonal effect on expression of the apical membrane calcium transport protein, TRPV6. Treatment with the hPXR agonist rifampin significantly increased CYP3A4 mRNA content and catalytic activity, but had no effect on CYP24A1 or TRPV6 mRNA content. Pre-treating cells with rifampin for 48h, prior to a 24h 1α,25(OH)(2)D(3) treatment phase, was associated with a subsequent 48% increase in the elimination of 1α,25(OH)(2)D(3) and a 35% reduction of peak TRPV6 mRNA. Introduction of the CYP3A4 inhibitor, 6',7'-dihydroxybergamottin, an active inhibitor in grapefruit juice, reversed the effects of rifampin on 1α,25(OH)(2)D(3) clearance and TRPV6 expression. Over-expression of hPXR in LS180 cells greatly enhanced the CYP3A4 responsiveness to rifampin pretreatment, and elicited a greater relative suppression of TRPV6 expression and an increase in 1α,25(OH)(2)D(3) disappearance rate, compared to vector expressed cells, following hormone administration. Together, these results suggest that induction of CYP3A4 in the intestinal epithelium by hPXR agonists can result in a greater metabolic clearance of 1α,25(OH)(2)D(3) and reduced effects of the hormone on the intestinal calcium absorption, which may contribute to an increased risk of drug-induced osteomalacia/osteoporosis in patients receiving chronic therapy with potent hPXR agonists. Moreover, ingestion of grapefruit juice in the at-risk patients could potentially prevent this adverse drug effect.
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Affiliation(s)
- Xi Emily Zheng
- Department of Pharmaceutics, University of Washington, Seattle, WA 98195-7610, United States
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Abstract
The human pregnane X receptor (PXR) is a ligand dependent transcription factor that can be activated by structurally diverse agonists including steroid hormones, bile acids, herbal drugs, and prescription medications. PXR regulates the transcription of several genes involved in xenobiotic detoxification and apoptosis. Activation of PXR has the potential to initiate adverse effects by altering drug pharmacokinetics or perturbing physiological processes. Hence, more reliable prediction of PXR activators would be valuable for pharmaceutical drug discovery to avoid potential toxic effects. Ligand- and protein structure-based computational models for PXR activation have been developed in several studies. There has been limited success with structure-based modeling approaches to predict human PXR activators, which can be attributed to the large and promiscuous site of this protein. Slightly better success has been achieved with ligand-based modeling methods including quantitative structure-activity relationship (QSAR) analysis, pharmacophore modeling and machine learning that use appropriate descriptors to account for the diversity of the ligand classes that bind to PXR. These combined computational approaches using molecular shape information may assist scientists to more confidently identify PXR activators. This chapter reviews the various ligand and structure based methods undertaken to date and their results.
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Affiliation(s)
- Sandhya Kortagere
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, USA.
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Abstract
Interindividual differences in drug transporter expression can result in variability in drug response. This variation in gene expression is determined, in part, by the actions of nuclear hormone receptors that act as xenobiotic- and endobiotic-sensing transcription factors. Among the ligand-activated nuclear receptors, signaling through the pregnane X receptor (PXR), constitutive androstane receptor (CAR), farnesoid X receptor (FXR), and vitamin D receptor (VDR) constitute major pathways regulating drug transporter expression in tissues. Hence, these endobiotic- and xenobiotic-sensing nuclear receptors are intrinsically involved in environmental influences of drug response. Moreover, because nuclear receptor genes are polymorphic, these transcription factors are also thought to contribute to heritability of variable drug action. In this chapter, the molecular aspects of drug transporter gene regulation by ligand-activated nuclear receptors will be reviewed including their clinical relevance.
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Gahir SS, Piquette-Miller M. Gestational and pregnane X receptor-mediated regulation of placental ATP-binding cassette drug transporters in mice. Drug Metab Dispos 2010; 39:465-71. [PMID: 21127142 DOI: 10.1124/dmd.110.034983] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The ATP-binding cassette (ABC) drug transporters in the placenta are involved in controlling the exchange of endogenous and exogenous moieties. Pregnane X receptor (PXR) is a nuclear receptor that regulates the hepatic expression of several key ABC transporters, but it is unclear whether PXR is involved in the regulation of these transporters in the placenta. This study explores the role of PXR in the regulation of placental drug transporters. The placental mRNA expression of Mdr1a, Bcrp, and Mrp1, 2, and 3 was examined in PXR knockout (-/-), heterozygote (+/-), and wild-type (+/+) mice by quantitative PCR. The impact of PXR activation was examined in pregnant pregnane-16α-carbonitrile (PCN)-treated mice. Compared with that in controls, the basal expression of Mdr1a, Bcrp, Mrp1, and Mrp2 was significantly higher in (+/-) and (-/-) mice. Alterations in the expression of mdr1a, bcrp, and mrp1, 2, and 3 between gestational day (GD) 10 and GD 17 was dissimilar between (+/+) and (-/-) mice. Although PCN treatment induced maternal and fetal hepatic expression of Cyp3a11; placental expression of transporters were not significantly changed. Overall, our results suggest a repressive role of PXR in the basal expression of several placental transporters and a tissue-specific induction of these target genes after PXR activation.
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Affiliation(s)
- Sarabjit S Gahir
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
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Chung JY, Cho JY, Lim HS, Kim JR, Yu KS, Lim KS, Shin SG, Jang IJ. Effects of pregnane X receptor (NR1I2) and CYP2B6 genetic polymorphisms on the induction of bupropion hydroxylation by rifampin. Drug Metab Dispos 2010; 39:92-7. [PMID: 20876786 DOI: 10.1124/dmd.110.035246] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We investigated genetic polymorphisms in the pregnane X receptor (NR1I2) in Korean individuals (n = 83) and the effects of NR1I2 genotypes on rifampin-mediated induction of bupropion hydroxylation. The pharmacokinetics of bupropion and hydroxybupropion were evaluated after an oral dose of bupropion (150 mg) administered before and after rifampin treatment for 7 days in 35 healthy subjects. The area under the time-concentration curve (AUC) ratio of hydroxybupropion to bupropion in CYP2B6*6 carriers was significantly lower than that in CYP2B6*6 noncarriers in both the basal and rifampin-induced states (p = 0.012). Among the CYP2B6*6 carriers (n = 13), the NR1I2 TGT (-25385T + g.7635G + g.8055T) carriers exhibited a significantly lower AUC ratio, representing the CYP2B6 hydroxylation activity, compared with the TGT noncarriers, in the induced state (11.9 versus 20.3, p = 0.045). The percent difference in the AUC ratio between the basal and induced states was also significantly different (212% versus 58.8%, p = 0.006). However, no significant difference was observed among the NR1I2 TGT genotypes for the CYP2B6*6 noncarriers (n = 22). In conclusion, it is suggested the NR1I2 TGT genotype decreases the bupropion hydroxylation induced by treatment with rifampin, particularly in CYP2B6*6 carriers.
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Affiliation(s)
- Jae Yong Chung
- Department of Pharmacology and Clinical Pharmacology, Yonsei University College of Medicine and Severance Hospital, Seoul, Korea
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Perera MA. The missing linkage: what pharmacogenetic associations are left to find in CYP3A? Expert Opin Drug Metab Toxicol 2010; 6:17-28. [PMID: 19968573 DOI: 10.1517/17425250903379546] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
IMPORTANCE OF THE FIELD An enormous amount of drugs and endogenous substrates are metabolized by the enzymes encoded in the CYP3A gene cluster, making variation at this locus of utmost importance in the field of pharmacogenetics. However, the identification of genetic variation that contributes to the wide phenotypic variability at this locus has been elusive. While dozens of studies have investigated the effects of coding variants, none have found the definitive answer to what variant or variants explain the distribution of enzyme activity and clinical effects seen with the drug metabolized by these genes. AREAS COVERED IN THIS REVIEW This review highlights the recent pharmacogenetic work at the CYP3A locus, in particular studies on known functional variants in CYP3A4 and CYP3A5. In addition, common pharmacogenetic strategies as well as considerations specific to the CYP3A locus are discussed. WHAT THE READER WILL GAIN The reader will gain a greater understanding of the complexities involved in studying the CYP3A locus, population differences that may affect pharmacogenetic studies at this locus and the importance of variation that affect gene regulation. TAKE HOME MESSAGE More innovative and comprehensive methods to assay this region are needed, with particular attention paid to the role of gene regulation and non-coding sequence.
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Affiliation(s)
- Minoli A Perera
- University of Chicago, Section of Genetic Medicine and Committee on Clinical Pharmacology and Pharmacogenomics, Division of Biological Sciences, Department of Medicine, Chicago, IL 60637, USA.
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Margolis RN, Moore DD, Willson TM, Guy RK. Chemical approaches to nuclear receptors in metabolism. Sci Signal 2009; 2:mr5. [PMID: 19654413 DOI: 10.1126/scisignal.282mr5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) sponsored a workshop, "Chemical Approaches to Nuclear Receptors and Metabolism," in April 2009 to explore how chemical and molecular biology and physiology can be exploited to further our understanding of nuclear receptor structure, function, and role in disease. Signaling cascades involving nuclear receptors are more complex and interrelated than once thought. Nuclear receptors continue to be attractive targets for drug discovery. The overall goal of this workshop was to identify gaps in our understanding of the complexity of ligand activities and begin to address them by (i) increasing the collaboration of investigators from different disciplines, (ii) developing a better understanding of chemical modulation of nuclear receptor action, and (iii) identifying opportunities and roadblocks in the path of translating basic research to discovery of new therapeutics.
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Affiliation(s)
- Ronald N Margolis
- Division of Diabetes, Endocrinology, and Metabolic Diseases, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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di Masi A, De Marinis E, Ascenzi P, Marino M. Nuclear receptors CAR and PXR: Molecular, functional, and biomedical aspects. Mol Aspects Med 2009; 30:297-343. [PMID: 19427329 DOI: 10.1016/j.mam.2009.04.002] [Citation(s) in RCA: 213] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 04/28/2009] [Indexed: 12/31/2022]
Abstract
Nuclear receptors (NRs) are ligand-activated transcription factors sharing a common evolutionary history and having similar sequence features at the protein level. Selective ligand(s) for some NRs is not known, therefore these NRs have been named "orphan receptors". Whenever ligands have been recognized for any of the orphan receptor, it has been categorized and grouped as "adopted" orphan receptor. This group includes the constitutive androstane receptor (CAR) and the pregnane X receptor (PXR). They function as sensors of toxic byproducts derived from endogenous metabolites and of exogenous chemicals, in order to enhance their elimination. This unique function of CAR and PXR sets them apart from the steroid hormone receptors. The broad response profile has established that CAR and PXR are xenobiotic sensors that coordinately regulate xenobiotic clearance in the liver and intestine via induction of genes involved in drug and xenobiotic metabolism. In the past few years, research has revealed new and mostly unsuspected roles for CAR and PXR in modulating hormone, lipid, and energy homeostasis as well as cancer and liver steatosis. The purpose of this review is to highlight the structural and molecular bases of CAR and PXR impact on human health, providing information on mechanisms through which diet, chemical exposure, and environment ultimately impact health and disease.
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Affiliation(s)
- Alessandra di Masi
- Department of Biology, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy
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31
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Biswas A, Mani S, Redinbo MR, Krasowski MD, Li H, Ekins S. Elucidating the 'Jekyll and Hyde' nature of PXR: the case for discovering antagonists or allosteric antagonists. Pharm Res 2009; 26:1807-15. [PMID: 19415465 DOI: 10.1007/s11095-009-9901-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Accepted: 04/16/2009] [Indexed: 12/15/2022]
Abstract
The pregnane X receptor belongs to the nuclear hormone receptor superfamily and is involved in the transcriptional control of numerous genes. It was originally thought that it was a xenobiotic sensor controlling detoxification pathways. Recent studies have shown an increasingly important role in inflammation and cancer, supporting its function in abrogating tissue damage. PXR orthologs and PXR-like pathways have been identified in several non-mammalian species which corroborate a conserved role for PXR in cellular detoxification. In summary, PXR has a multiplicity of roles in vivo and is being revealed as behaving like a "Jekyll and Hyde" nuclear hormone receptor. The importance of this review is to elucidate the need for discovery of antagonists of PXR to further probe its biology and therapeutic applications. Although several PXR agonists are already reported, virtually nothing is known about PXR antagonists. Here, we propose the development of PXR antagonists through chemical, genetic and molecular modeling approaches. Based on this review it will be clear that antagonists of PXR and PXR-like pathways will have widespread utility in PXR biology and therapeutics.
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Affiliation(s)
- Arunima Biswas
- Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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