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Li Z, Li L, Heyward S, Men S, Xu M, Sueyoshi T, Wang H. Phenobarbital Induces SLC13A5 Expression through Activation of PXR but Not CAR in Human Primary Hepatocytes. Cells 2021; 10:cells10123381. [PMID: 34943889 PMCID: PMC8699749 DOI: 10.3390/cells10123381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 02/05/2023] Open
Abstract
Phenobarbital (PB), a widely used antiepileptic drug, is known to upregulate the expression of numerous drug-metabolizing enzymes and transporters in the liver primarily via activation of the constitutive androstane receptor (CAR, NR1I3). The solute carrier family 13 member 5 (SLC13A5), a sodium-coupled citrate transporter, plays an important role in intracellular citrate homeostasis that is associated with a number of metabolic syndromes and neurological disorders. Here, we show that PB markedly elevates the expression of SLC13A5 through a pregnane X receptor (PXR)-dependent but CAR-independent signaling pathway. In human primary hepatocytes, the mRNA and protein expression of SLC13A5 was robustly induced by PB treatment, while genetic knockdown or pharmacological inhibition of PXR significantly attenuated this induction. Utilizing genetically modified HepaRG cells, we found that PB induces SLC13A5 expression in both wild type and CAR-knockout HepaRG cells, whereas such induction was fully abolished in the PXR-knockout HepaRG cells. Mechanistically, we identified and functionally characterized three enhancer modules located upstream from the transcription start site or introns of the SLC13A5 gene that are associated with the regulation of PXR-mediated SLC13A5 induction. Moreover, metformin, a deactivator of PXR, dramatically suppressed PB-mediated induction of hepatic SLC13A5 as well as its activation of the SLC13A5 luciferase reporter activity via PXR. Collectively, these data reveal PB as a potent inducer of SLC13A5 through the activation of PXR but not CAR in human primary hepatocytes.
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Affiliation(s)
- Zhihui Li
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, USA; (Z.L.); (L.L.); (S.M.)
| | - Linhao Li
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, USA; (Z.L.); (L.L.); (S.M.)
| | - Scott Heyward
- BioIVT, 1450 S Rolling Road, Halethorpe, MD 21227, USA;
| | - Shuaiqian Men
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, USA; (Z.L.); (L.L.); (S.M.)
| | - Meishu Xu
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261, USA;
| | - Tatsuya Sueyoshi
- Pharmacogenetics Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA;
| | - Hongbing Wang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, USA; (Z.L.); (L.L.); (S.M.)
- Correspondence: ; Tel.: +1-410-706-1280
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Shizu R, Nishiguchi H, Tashiro S, Sato T, Sugawara A, Kanno Y, Hosaka T, Sasaki T, Yoshinari K. Helix 12 stabilization contributes to basal transcriptional activity of PXR. J Biol Chem 2021; 297:100978. [PMID: 34284062 PMCID: PMC8390552 DOI: 10.1016/j.jbc.2021.100978] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/12/2021] [Accepted: 07/16/2021] [Indexed: 11/19/2022] Open
Abstract
Pregnane X receptor (PXR) plays an important role in xenobiotic metabolism. While ligand binding induces PXR-dependent gene transcription, PXR shows constitutive transcriptional activity in the absence of ligands when expressed in cultured cells. This constitutive activity sometimes hampers investigation of PXR activation by compounds of interest. In this study, we investigated the molecular mechanism of PXR activation. In the reported crystal structures of unliganded PXR, helix 12 (H12), including a coactivator binding motif, was stabilized, while it is destabilized in the unliganded structures of other nuclear receptors, suggesting a role for H12 stabilization in the basal activity of PXR. Since Phe420, located in the loop between H11 and H12, is thought to interact with Leu411 and Ile414 to stabilize H12, we substituted alanine at Phe420 (PXR-F420A) and separately inserted three alanine residues directly after Phe420 (PXR-3A) and investigated their influence on PXR-mediated transcription. Reporter gene assays demonstrated that the mutants showed drastically reduced basal activity and enhanced responses to various ligands, which was further enhanced by coexpression of the coactivator peroxisome proliferator-activated receptor gamma coactivator 1α. Mutations of both Leu411 and Ile414 to alanine also suppressed basal activity. Mammalian two-hybrid assays showed that PXR-F420A and PXR-3A bound to corepressors and coactivators in the absence and presence of ligands, respectively. We conclude that the intramolecular interactions of Phe420 with Leu411 and Ile414 stabilize H12 to recruit coactivators even in the absence of ligands, contributing to the basal transcriptional activity of PXR. We propose that the generated mutants might be useful for PXR ligand screening.
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Affiliation(s)
- Ryota Shizu
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
| | - Hikaru Nishiguchi
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Sarii Tashiro
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Takumi Sato
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Ayaka Sugawara
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Yuichiro Kanno
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Takuomi Hosaka
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Takamitsu Sasaki
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Kouichi Yoshinari
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
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Wang J, Bwayi M, Florke Gee RR, Chen T. PXR-mediated idiosyncratic drug-induced liver injury: mechanistic insights and targeting approaches. Expert Opin Drug Metab Toxicol 2020; 16:711-722. [PMID: 32500752 PMCID: PMC7429329 DOI: 10.1080/17425255.2020.1779701] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 06/04/2020] [Indexed: 01/03/2023]
Abstract
INTRODUCTION The human liver is the center for drug metabolism and detoxification and is, therefore, constantly exposed to toxic chemicals. The loss of liver function as a result of this exposure is referred to as drug-induced liver injury (DILI). The pregnane X receptor (PXR) is the primary regulator of the hepatic drug-clearance system, which plays a critical role in mediating idiosyncratic DILI. AREAS COVERED This review is focused on common mechanisms of PXR-mediated DILI and on in vitro and in vivo models developed to predict and assess DILI. It also provides an update on the development of PXR antagonists that may manage PXR-mediated DILI. EXPERT OPINION DILI can be caused by many factors, and PXR is clearly linked to DILI. Although emerging data illustrate how PXR mediates DILI and how PXR activity can be modulated, many questions concerning the development of effective PXR modulators remain. Future research should be focused on determining the mechanisms regulating PXR functions in different cellular contexts.
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Affiliation(s)
- Jingheng Wang
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Monicah Bwayi
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Rebecca R. Florke Gee
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
- Graduate School of Biomedical Sciences, St. Jude Children’s Research Hospital, 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
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Shen Y, Shi Z, Fan JT, Yan B. Dechlorination and demethylation of ochratoxin A enhance blocking activity of PXR activation, suppress PXR expression and reduce cytotoxicity. Toxicol Lett 2020; 332:171-180. [PMID: 32659470 DOI: 10.1016/j.toxlet.2020.07.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 06/28/2020] [Accepted: 07/09/2020] [Indexed: 12/16/2022]
Abstract
The pregnane X receptor (PXR) has been established to induce chemoresistance and metabolic diseases. Ochratoxin A (OTA), a mycotoxin, decreases the expression of PXR protein in human primary hepatocytes. OTA is chlorinated and has a methylated lactone ring. Both structures are associated with OTA toxicity. The study was to test the hypothesis that structural modifications differentially impact PXR blocking activity over cytotoxicity. To test this hypothesis, OTA-M and OTA-Cl/M were synthesized. OTA-M lacked the methyl group of the lactone-ring, whereas OTA-Cl/M had neither the methyl group nor the chlorine atom. The blocking activity of PXR activation was determined in a stable cell line, harboring both PXR (coding sequence) and its luciferase element reporter. OTA-Cl/M showed the highest blocking activity, followed by OTA-M and OTA. OTA-Cl/M was 60 times as potent as the common PXR blocker ketoconazole based on calculated IC50 values. OTA-Cl/M decreased by 90 % the expression of PXR protein and was the least cytotoxic among the tested compounds. Molecular docking identified that OTA and its derivatives interacted with different sets of residues in PXR, providing a molecular basis for selectivity. Excessive activation of PXR has been implicated in chemoresistance and metabolic diseases. Downregulation of PXR protein expression likely delivers an effective mechanism against structurally diverse PXR agonists.
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Affiliation(s)
- Yuanjun Shen
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH, 45229, USA
| | - Zhanquan Shi
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH, 45229, USA
| | - Jun Ting Fan
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH, 45229, USA
| | - Bingfang Yan
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH, 45229, USA.
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Yu Z, Seya K, Chiyoya M, Daitoku K, Motomura S, Imaizumi T, Fukuda I, Furukawa KI. Warfarin calcifies human aortic valve interstitial cells at high-phosphate conditions via pregnane X receptor. J Bone Miner Metab 2019; 37:944-956. [PMID: 30963258 DOI: 10.1007/s00774-019-01001-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 03/18/2019] [Indexed: 10/27/2022]
Abstract
Warfarin, a vitamin K antagonist, is the most common anticoagulant used to prevent thromboembolisms associated with atrial fibrillation or following valvular surgery. Although several studies have revealed that long-term warfarin use accelerates aortic valve calcification and the development of aortic stenosis (AS), the detailed mechanism for this phenomenon remains unclear. Therefore, our aim was twofold: to establish the conditions for warfarin-induced calcification of human aortic valve interstitial cells (HAVICs) using high-inorganic phosphate (Pi) conditions and to investigate the underlying mechanism. We prepared and cultured HAVICs from aortic valves affected by calcific aortic valve stenosis (AS group) and aortic valves affected by aortic regurgitation but without any signs of calcification (non-AS group). Under Pi concentrations of 3.2 mM, warfarin significantly increased the calcification and alkaline phosphatase (ALP) activity of AS but not non-AS group HAVICs. Furthermore, gene expression of bone morphogenetic protein 2 (BMP2), a calcigenic marker, was significantly increased following 7 days of warfarin treatment. Warfarin-induced calcification of AS group HAVICs at 3.2 mM Pi was significantly inhibited by dorsomorphin, a Smad inhibitor, and the pregnane X receptor (PXR) inhibitors, ketoconazole and coumestrol, but was unaffected by SN-50, an NF-κB inhibitor. Warfarin was also able to increase BMP2 gene expression at a physiological Pi concentration (1.0 mM). Furthermore, excess BMP2 (30 ng/mL) facilitated warfarin-induced ALP upregulation and HAVIC calcification, an effect which was significantly reduced in the presence of coumestrol. Together, our results suggest that warfarin accelerates calcification of HAVICs from AS patients via the PXR-BMP2-ALP pathway.
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Affiliation(s)
- Zaiqiang Yu
- Department of Thoracic and Cardiovascular Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Kazuhiko Seya
- Department of Vascular Biology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Mari Chiyoya
- Department of Thoracic and Cardiovascular Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Kazuyuki Daitoku
- Department of Thoracic and Cardiovascular Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Shigeru Motomura
- Department of Pharmacology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Tadaatsu Imaizumi
- Department of Vascular Biology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Ikuo Fukuda
- Department of Thoracic and Cardiovascular Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Ken-Ichi Furukawa
- Department of Pharmacology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
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Abstract
The canonical effect of Pregnane X Receptor (PXR, NR1I2) agonism includes enhanced hepatic uptake and a concomitant increase in the first-pass metabolism and efflux of drugs in mammalian liver and intestine. In patients undergoing combination therapy, PXR-mediated gene regulation represents the molecular basis of numerous food-drug, herb-drug, and drug-drug interactions. Moreover, PXR activation promotes chemotherapeutic resistance in certain malignancies. Additional research efforts suggest that sustained PXR activation exacerbates the development of fatty liver disease. Additional metabolic effects of PXR activation in liver are the inhibition of fatty acid oxidation and gluconeogenesis. The identification of non-toxic and selective PXR antagonists is therefore of current research interest. Inhibition of PXR should decrease adverse effects, improve therapeutic effectiveness, and advance clinical outcomes in patients with cancer, fatty liver, and diabetes. This review identifies small molecule PXR antagonists described to date, discusses possible molecular mechanisms of inhibition, and seeks to describe the likely biomedical consequences of the inhibition of this nuclear receptor superfamily member.
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Affiliation(s)
- Jeff L Staudinger
- Basic Sciences, Kansas City University of Medicine and Biosciences, Joplin, MO, USA.
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