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Rakateli L, Huchzermeier R, van der Vorst EPC. AhR, PXR and CAR: From Xenobiotic Receptors to Metabolic Sensors. Cells 2023; 12:2752. [PMID: 38067179 PMCID: PMC10705969 DOI: 10.3390/cells12232752] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 11/23/2023] [Accepted: 11/30/2023] [Indexed: 12/18/2023] Open
Abstract
Traditionally, xenobiotic receptors are known for their role in chemical sensing and detoxification, as receptor activation regulates the expression of various key enzymes and receptors. However, recent studies have highlighted that xenobiotic receptors also play a key role in the regulation of lipid metabolism and therefore function also as metabolic sensors. Since dyslipidemia is a major risk factor for various cardiometabolic diseases, like atherosclerosis and non-alcoholic fatty liver disease, it is of major importance to understand the molecular mechanisms that are regulated by xenobiotic receptors. In this review, three major xenobiotic receptors will be discussed, being the aryl hydrocarbon receptor (AhR), pregnane X receptor (PXR) and the constitutive androstane receptor (CAR). Specifically, this review will focus on recent insights into the metabolic functions of these receptors, especially in the field of lipid metabolism and the associated dyslipidemia.
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Affiliation(s)
- Leonida Rakateli
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany; (L.R.); (R.H.)
- Aachen-Maastricht Institute for CardioRenal Disease (AMICARE), RWTH Aachen University, 52074 Aachen, Germany
| | - Rosanna Huchzermeier
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany; (L.R.); (R.H.)
- Aachen-Maastricht Institute for CardioRenal Disease (AMICARE), RWTH Aachen University, 52074 Aachen, Germany
| | - Emiel P. C. van der Vorst
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany; (L.R.); (R.H.)
- Aachen-Maastricht Institute for CardioRenal Disease (AMICARE), RWTH Aachen University, 52074 Aachen, Germany
- Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximilians-University Munich, 80336 Munich, Germany
- Interdisciplinary Center for Clinical Research (IZKF), RWTH Aachen University, 52074 Aachen, Germany
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Klatt KC, Petviashvili EJ, Moore DD. LRH-1 induces hepatoprotective nonessential amino acids in response to acute liver injury. J Clin Invest 2023; 133:168805. [PMID: 37009899 PMCID: PMC10065065 DOI: 10.1172/jci168805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2023] Open
Abstract
Acute hepatic injury is observed in response to various stressors, including trauma, ingestion of hepatic toxins, and hepatitis. Investigations to date have focused on extrinsic and intrinsic signals required for hepatocytes to proliferate and regenerate the liver in response to injury, though there is a more limited understanding of induced stress responses promoting hepatocyte survival upon acute injury. In this issue of the JCI, Sun and colleagues detail a mechanism by which local activation of the nuclear receptor liver receptor homolog-1 (LRH-1; NR5A2) directly induces de novo asparagine synthesis and expression of asparagine synthetase (ASNS) in response to injury and show that this response restrains hepatic damage. This work opens up several avenues for inquiry, including the potential for asparagine supplementation to ameliorate acute hepatic injury.
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Pan S, Guo Y, Yu W, Hong F, Qiao X, Zhang J, Xu P, Zhai Y. Environmental chemical TCPOBOP disrupts milk lipid homeostasis during pregnancy and lactation. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 249:114463. [PMID: 38321682 DOI: 10.1016/j.ecoenv.2022.114463] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 12/12/2022] [Accepted: 12/21/2022] [Indexed: 02/08/2024]
Abstract
Humans are exposed to different kinds of environmental contaminants or drugs throughout their lifetimes. The widespread presence of these compounds has raised concerns about the consequent adverse effects on lactating women. The constitutive androstane receptor (CAR, Nr1i3) is known as a xenobiotic sensor for environmental pollution or drugs. In this study, the model environmental chemical 1, 4-bis [2-(3, 5-dichloropyridyloxy)] benzene, TCPOBOP (TC), which is a highly specific agonist of CAR, was used to investigate the effects of exogenous exposure on lactation function and offspring health in mice. The results revealed that TC exposure decreased the proliferation of mammary epithelial cells during pregnancy. This deficiency further compromised lobular-alveolar structures, resulting in alveolar cell apoptosis, as well as premature stoppage of the lactation cycle and aberrant lactation. Furthermore, TC exposure significantly altered the size and number of milk lipid droplets, suggesting that TC exposure inhibits milk lipid synthesis. Additionally, TC exposure interfered with the milk lipid metabolism network, resulting in the inability of TC-exposed mice to efficiently secrete nutrients and feed their offspring. These findings demonstrated that restricted synthesis and secretion of milk lipids would indirectly block mammary gland form and function, which explained the possible reasons for lactation failure and retarded offspring growth.
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Affiliation(s)
- Shijia Pan
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China; Key Laboratory for Cell Proliferation and Regulation Biology of State Education Ministry, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
| | - Yuan Guo
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China; Key Laboratory for Cell Proliferation and Regulation Biology of State Education Ministry, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
| | - Wen Yu
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China; Key Laboratory for Cell Proliferation and Regulation Biology of State Education Ministry, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
| | - Fan Hong
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China; Key Laboratory for Cell Proliferation and Regulation Biology of State Education Ministry, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
| | - Xiaoxiao Qiao
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China; Key Laboratory for Cell Proliferation and Regulation Biology of State Education Ministry, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
| | - Jia Zhang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China; Key Laboratory for Cell Proliferation and Regulation Biology of State Education Ministry, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
| | - Pengfei Xu
- School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China; Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261, USA.
| | - Yonggong Zhai
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China; Key Laboratory for Cell Proliferation and Regulation Biology of State Education Ministry, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
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Banerjee B, Olajide OJ, Bortolussi G, Muro AF. Activation of Alternative Bilirubin Clearance Pathways Partially Reduces Hyperbilirubinemia in a Mouse Model Lacking Functional Ugt1a1 Activity. Int J Mol Sci 2022; 23:ijms231810703. [PMID: 36142606 PMCID: PMC9505366 DOI: 10.3390/ijms231810703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/08/2022] [Accepted: 09/11/2022] [Indexed: 11/21/2022] Open
Abstract
Bilirubin is a heme catabolite and Ugt1a1 is the only enzyme involved in the biological elimination of bilirubin. Partially functional or non-functional Ugt1a1 may result in neuronal damage and death due to the accumulation of unconjugated bilirubin in the brain. The understanding of the role of alternative bilirubin detoxification mechanisms that can reduce bilirubin toxicity risk is crucial for developing novel therapeutic strategies. To provide a proof-of-principle showing whether activation of alternative detoxification pathways could lead to life-compatible bilirubin levels in the absence of Ugt1a1 activity, we used Ugt1−/− hyperbilirubinemic mice devoid of bilirubin glucuronidation activity. We treated adult Ugt1−/− mice with TCPOBOP, a strong agonist of the constitutive androstane receptor (CAR). TCPOBOP treatment decreased plasma and liver tissue bilirubin levels by about 38%, and resulted in the transcriptional activation of a vast array of genes involved in bilirubin transport and metabolism. However, brain bilirubin level was unaltered. We observed ~40% degradation of bilirubin in the liver microsomes from TCPOBOP treated Ugt1−/− mice. Our findings suggest that, in the absence of Ugt1a1, the activation of alternative bilirubin clearance pathways can partially improve hyperbilirubinemic conditions. This therapeutic approach may only be considered in a combinatorial manner along with other treatments.
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Wu BK, Mei SC, Chen EH, Zheng Y, Pan D. YAP induces an oncogenic transcriptional program through TET1-mediated epigenetic remodeling in liver growth and tumorigenesis. Nat Genet 2022; 54:1202-1213. [PMID: 35835915 PMCID: PMC9357225 DOI: 10.1038/s41588-022-01119-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 06/02/2022] [Indexed: 02/03/2023]
Abstract
Epigenetic remodeling is essential for oncogene-induced cellular transformation and malignancy. In contrast to histone post-translational modifications, how DNA methylation is remodeled by oncogenic signaling remains poorly understood. The oncoprotein YAP, a coactivator of the TEAD transcription factors mediating Hippo signaling, is widely activated in human cancers. Here, we identify the 5-methylcytosine dioxygenase TET1 as a direct YAP target and a master regulator that coordinates the genome-wide epigenetic and transcriptional reprogramming of YAP target genes in the liver. YAP activation induces the expression of TET1, which physically interacts with TEAD to cause regional DNA demethylation, histone H3K27 acetylation and chromatin opening in YAP target genes to facilitate transcriptional activation. Loss of TET1 not only reverses YAP-induced epigenetic and transcriptional changes but also suppresses YAP-induced hepatomegaly and tumorigenesis. These findings exemplify how oncogenic signaling regulates the site specificity of DNA demethylation to promote tumorigenesis and implicate TET1 as a potential target for modulating YAP signaling in physiology and disease.
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Affiliation(s)
- Bo-Kuan Wu
- Department of Physiology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Szu-Chieh Mei
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Elizabeth H Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yonggang Zheng
- Department of Physiology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Duojia Pan
- Department of Physiology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Little M, Dutta M, Li H, Matson A, Shi X, Mascarinas G, Molla B, Weigel K, Gu H, Mani S, Cui JY. Understanding the physiological functions of the host xenobiotic-sensing nuclear receptors PXR and CAR on the gut microbiome using genetically modified mice. Acta Pharm Sin B 2022; 12:801-820. [PMID: 35256948 PMCID: PMC8897037 DOI: 10.1016/j.apsb.2021.07.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/29/2021] [Accepted: 07/09/2021] [Indexed: 12/12/2022] Open
Abstract
Pharmacological activation of the xenobiotic-sensing nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) is well-known to increase drug metabolism and reduce inflammation. Little is known regarding their physiological functions on the gut microbiome. In this study, we discovered bivalent hormetic functions of PXR/CAR modulating the richness of the gut microbiome using genetically engineered mice. The absence of PXR or CAR increased microbial richness, and absence of both receptors synergistically increased microbial richness. PXR and CAR deficiency increased the pro-inflammatory bacteria Helicobacteraceae and Helicobacter. Deficiency in both PXR and CAR increased the relative abundance of Lactobacillus, which has bile salt hydrolase activity, corresponding to decreased primary taurine-conjugated bile acids (BAs) in feces, which may lead to higher internal burden of taurine and unconjugated BAs, both of which are linked to inflammation, oxidative stress, and cytotoxicity. The basal effect of PXR/CAR on the gut microbiome was distinct from pharmacological and toxicological activation of these receptors. Common PXR/CAR-targeted bacteria were identified, the majority of which were suppressed by these receptors. hPXR-TG mice had a distinct microbial profile as compared to wild-type mice. This study is the first to unveil the basal functions of PXR and CAR on the gut microbiome.
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Key Words
- BA, bile acid
- BSH, bile salt hydrolase
- Bile acids
- CA, cholic acid
- CAR
- CAR, constitutive androstane receptor
- CDCA, chenodeoxycholic acid
- CITCO, 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime
- CV, conventional
- CYP, cytochrome P450
- DCA, deoxycholic acid
- EGF, epidermal growth factor
- Feces
- GF, germ free
- GLP-1, glucagon-like peptide-1
- GM-CSF, granulocyte-macrophage colony-stimulating factor
- Gut microbiome
- HDCA, hyodeoxycholic acid
- IBD, inflammatory bowel disease
- IFNγ, interferon-gamma
- IL, interleukin
- IS, internal standards
- Inflammation
- LCA, lithocholic acid
- LC–MS/MS, liquid chromatography–tandem mass spectrometry
- MCA, muricholic acid
- MCP-1, monocyte chemoattractant protein-1
- Mice
- NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells
- NSAID, non-steroidal anti-inflammatory drug
- Nuclear receptor
- OH, hydroxylated
- OTUs, operational taxonomy units
- PA, indole-3 propionic acid
- PBDEs, polybrominated diphenyl ethers
- PCBs, polychlorinated biphenyls
- PCoA, Principle Coordinate Analysis
- PXR
- PXR, pregnane X receptor
- PiCRUSt, Phylogenetic Investigation of Communities by Reconstruction of Observed States
- QIIME, Quantitative Insights Into Microbial Ecology
- SCFAs, short-chain fatty acids
- SNP, single-nucleotide polymorphism
- SPF, specific-pathogen-free
- T, wild type
- T-, taurine conjugated
- TCPOBOP, 1,4-bis-[2-(3,5-dichloropyridyloxy)]benzene, 3,3′,5,5′-Tetrachloro-1,4-bis(pyridyloxy)benzene
- TGR-5, Takeda G-protein-coupled receptor 5
- TLR4, toll-like receptor 4
- TNF, tumor necrosis factor
- UDCA, ursodeoxycholic acid
- YAP, yes-associated protein
- hPXR-TG, humanized PXR transgenic
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Affiliation(s)
- Mallory Little
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA
| | - Moumita Dutta
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA
| | - Hao Li
- Department of Medicine, Molecular Pharmacology and Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Adam Matson
- University of Connecticut, Hartford, CT 06106, USA
| | - Xiaojian Shi
- Arizona Metabolomics Laboratory, College of Health Solutions, Arizona State University, Phoenix, AZ 85004, USA
| | - Gabby Mascarinas
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA
| | - Bruk Molla
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA
| | - Kris Weigel
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA
| | - Haiwei Gu
- Arizona Metabolomics Laboratory, College of Health Solutions, Arizona State University, Phoenix, AZ 85004, USA
| | - Sridhar Mani
- Department of Medicine, Molecular Pharmacology and Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Julia Yue Cui
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA
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Tian J, Locker J. Gadd45 in the Liver: Signal Transduction and Transcriptional Mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1360:87-99. [DOI: 10.1007/978-3-030-94804-7_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Gährs M, Schrenk D. Suppression of apoptotic signaling in rat hepatocytes by non-dioxin-like polychlorinated biphenyls depends on the receptors CAR and PXR. Toxicology 2021; 464:153023. [PMID: 34743025 DOI: 10.1016/j.tox.2021.153023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 10/19/2021] [Accepted: 11/02/2021] [Indexed: 10/19/2022]
Abstract
Non-dioxin-like polychlorinated biphenyls (NDL-PCBs) represent a sub-group of persistent organic pollutants found in food, environmental samples and human and animal tissues. Promotion of pre-neoplastic lesions in rodent liver has been suggested as an indicator for a possible increased risk of liver cancer in humans exposed to NDL-PCBs. In rodent hepatocytes, suppression of DNA damage-triggered apoptosis is a typical mode of action of liver tumor promoters. Here, we report that NDL-PCBs suppress apoptosis in rat hepatocytes treated in culture with an apoptogenic dose of UV light. Suppression became less pronounced when the constitutive androstane receptor (CAR) and/or the pregnane-X-receptor (PXR) where knocked-out using siRNAs, while knocking-out both receptors led to a full reconstitution of apoptosis. In contrast, suppression of apoptosis by the CAR or PXR activators phenobarbital or dexamethasone were CAR- or PXR-specific. Induction and suppression of apoptosis were paralleled by changes in caspase 3/7, 8 and 9 activities. Our findings indicate that NDL-PCBs can suppress UV-induced apoptosis in rat hepatocytes by activating CAR and PXR. It needs further investigation if these mechanisms of action are also of relevance for human liver.
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Affiliation(s)
- Maike Gährs
- Food Chemistry and Toxicology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Dieter Schrenk
- Food Chemistry and Toxicology, University of Kaiserslautern, Kaiserslautern, Germany.
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Namachivayam A, Valsala Gopalakrishnan A. A review on molecular mechanism of alcoholic liver disease. Life Sci 2021; 274:119328. [PMID: 33711388 DOI: 10.1016/j.lfs.2021.119328] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/13/2021] [Accepted: 03/01/2021] [Indexed: 02/06/2023]
Abstract
Excessive alcohol consumption leads to damage to the organs of the body. More importantly, the liver is majorly affected organ upon alcohol consumption for most of the people; it causes inflammation and affects various pathways involved in metabolism. If the person is with high response of inflammatory in conduct with alcohol leads to the liver damage, which involves the creating effects with major cycle leads to homeostasis. In this review, we summarize the molecular mechanisms of alcoholic liver disease, such as the important role of genes, risk factors, pathogenicity, and role of micro RNA, the role of inflammation in the liver, and alcoholic fibrosis in the liver. There is increased oxidative stress, change in the biochemical alterations, and reduction in the antioxidant enzymes. These changes in the mechanism lead to liver injury. Hepatocyte nuclear factor-4 is the major transcriptional factor for the regulation of some genes involved in the lipid metabolism and oxidation process; with the help of the agonist, we can attenuate the level of the gene in the site of hepatic tissues, which will prevent the homeostatic condition. This review shows a clear view of the various pathways involved in alcohol consumption, which helps in the prevention of ALD using an agonist.
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Affiliation(s)
- Arunraj Namachivayam
- Department of Biomedical Sciences, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu 632014, India
| | - Abilash Valsala Gopalakrishnan
- Department of Biomedical Sciences, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu 632014, India.
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Dusek J, Skoda J, Holas O, Horvatova A, Smutny T, Linhartova L, Hirsova P, Kucera O, Micuda S, Braeuning A, Pavek P. Stilbene compound trans-3,4,5,4´-tetramethoxystilbene, a potential anticancer drug, regulates constitutive androstane receptor (Car) target genes, but does not possess proliferative activity in mouse liver. Toxicol Lett 2019; 313:1-10. [PMID: 31170421 DOI: 10.1016/j.toxlet.2019.05.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/21/2019] [Accepted: 05/29/2019] [Indexed: 01/06/2023]
Abstract
The constitutive androstane receptor(CAR) activation is connected with mitogenic effects leading to liver hyperplasia and tumorigenesis in rodents. CAR activators, including phenobarbital, are considered rodent non-genotoxic carcinogens. Recently, trans-3,4,5,4´-tetramethoxystilbene(TMS), a potential anticancer drug (DMU-212), have been shown to alleviate N-nitrosodiethylamine/phenobarbital-induced liver carcinogenesis. We studied whether TMS inhibits mouse Car to protect from the PB-induced tumorigenesis. Unexpectedly, we identified TMS as a murine CAR agonist in reporter gene experiments, in mouse hepatocytes, and in C57BL/6 mice in vivo. TMS up-regulated Car target genes Cyp2b10, Cyp2c29 and Cyp2c55 mRNAs, but down-regulated expression of genes involved in gluconeogenesis and lipogenesis. TMS did not change or down-regulate genes involved in liver proliferation or apoptosis such as Mki67, Foxm1, Myc, Mcl1, Pcna, Bcl2, or Mdm2, which were up-regulated by another Car ligand TCPOBOP. TMS did not increase liver weight and had no significant effect on Ki67 and Pcna labeling indices in mouse liver in vivo. In murine hepatic AML12 cells, we confirmed a Car-independent proapoptotic effect of TMS. We conclude that TMS is a Car ligand with limited effects on hepatocyte proliferation, likely due to promoting apoptosis in mouse hepatic cells, while controlling Car target genes involved in xenobiotic and endobiotic metabolism.
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Affiliation(s)
- Jan Dusek
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, Hradec Kralove, 500 05, Czech Republic
| | - Josef Skoda
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, Hradec Kralove, 500 05, Czech Republic
| | - Ondrej Holas
- Department of Pharmaceutical Technology, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, Hradec Kralove, 500 05, Czech Republic
| | - Alzbeta Horvatova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, Hradec Kralove, 500 05, Czech Republic
| | - Tomas Smutny
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, Hradec Kralove, 500 05, Czech Republic
| | - Lenka Linhartova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, Hradec Kralove, 500 05, Czech Republic
| | - Petra Hirsova
- Division of Gastroenterology and Hepatology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA
| | - Otto Kucera
- Department of Physiology, Charles University, Faculty of Medicine in Hradec Kralove, Simkova 870, 500 03 Hradec Kralove, Czech Republic
| | - Stanislav Micuda
- Department of Pharmacology, Charles University, Faculty of Medicine in Hradec Kralove, Simkova 870, 500 03 Hradec Kralove, Czech Republic
| | - Albert Braeuning
- Department of Food Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589, Berlin, Germany; Department of Toxicology, University of Tübingen, Wilhelmstr. 56, 72074, Tübingen, Germany
| | - Petr Pavek
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Charles University, Heyrovskeho 1203, Hradec Kralove, 500 05, Czech Republic.
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Moscovitz JE, Kalgutkar AS, Nulick K, Johnson N, Lin Z, Goosen TC, Weng Y. Establishing Transcriptional Signatures to Differentiate PXR-, CAR-, and AhR-Mediated Regulation of Drug Metabolism and Transport Genes in Cryopreserved Human Hepatocytes. J Pharmacol Exp Ther 2018; 365:262-271. [PMID: 29440451 DOI: 10.1124/jpet.117.247296] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 02/08/2018] [Indexed: 12/25/2022] Open
Abstract
The potential for drug-drug interactions (DDIs) arising from transcriptional regulation of drug-disposition genes via activation of nuclear receptors (NRs), such as pregnane X receptor (PXR), constitutive androstane receptor (CAR), and aryl hydrocarbon receptor (AhR), remains largely unexplored, as highlighted in a recent guidance document from the European Medicines Agency. The goal of this research was to establish PXR-/CAR-/AhR-specific drug-metabolizing enzyme (DME) and transporter gene expression signatures in sandwich-cultured cryopreserved human hepatocytes using selective activators of PXR (rifampin), CAR (CITCO), and AhR (omeprazole). Dose response for ligand-induced changes to 38 major human DMEs and critical hepatobiliary transporters were assessed using a custom gene expression array card. We identified novel differentially expressed drug-disposition genes for PXR (↑ABCB1/MDR1, CYP2C9, CYP2C19, and EPHX1, ↓ABCB11), CAR [↑sulfotransferase (SULT) 1E1, uridine glucuronosyl transferase (UGT) 2B4], and AhR (↑SLC10A1/NTCP, SLCO1B1/OATP1B1], and coregulated genes (CYP1A1, CYP2B6, CYP2C8, CYP3A4, UGT1A1, UGT1A4). Subsequently, DME gene expression signatures were generated for known CYP3A4 inducers PF-06282999 and pazopanib. The former produced an induction signature almost identical to that of rifampin, suggesting activation of the PXR pathway, whereas the latter produced an expression signature distinct from those of PXR, CAR, or AhR, suggesting involvement of an alternate pathway(s). These results demonstrate that involvement of PXR/CAR/AhR can be identified via expression changes of signature DME/transporter genes. Inclusion of such signature genes could serve to simultaneously identify potential inducers and inhibitors, and the NRs involved in the transcriptional regulation, thus providing a more holistic and mechanism-based assessment of DDI risk for DMEs and transporters beyond conventional cytochrome P450 isoforms.
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Affiliation(s)
- Jamie E Moscovitz
- Medicine Design, Pfizer Inc., Cambridge, Massachusetts (J.E.M., A.S.K., Y.W.), and Medicine Design, Pfizer Inc., Groton, Connecticut (K.N., N.J., Z.L., T.C.G.)
| | - Amit S Kalgutkar
- Medicine Design, Pfizer Inc., Cambridge, Massachusetts (J.E.M., A.S.K., Y.W.), and Medicine Design, Pfizer Inc., Groton, Connecticut (K.N., N.J., Z.L., T.C.G.)
| | - Kelly Nulick
- Medicine Design, Pfizer Inc., Cambridge, Massachusetts (J.E.M., A.S.K., Y.W.), and Medicine Design, Pfizer Inc., Groton, Connecticut (K.N., N.J., Z.L., T.C.G.)
| | - Nathaniel Johnson
- Medicine Design, Pfizer Inc., Cambridge, Massachusetts (J.E.M., A.S.K., Y.W.), and Medicine Design, Pfizer Inc., Groton, Connecticut (K.N., N.J., Z.L., T.C.G.)
| | - Zhiwu Lin
- Medicine Design, Pfizer Inc., Cambridge, Massachusetts (J.E.M., A.S.K., Y.W.), and Medicine Design, Pfizer Inc., Groton, Connecticut (K.N., N.J., Z.L., T.C.G.)
| | - Theunis C Goosen
- Medicine Design, Pfizer Inc., Cambridge, Massachusetts (J.E.M., A.S.K., Y.W.), and Medicine Design, Pfizer Inc., Groton, Connecticut (K.N., N.J., Z.L., T.C.G.)
| | - Yan Weng
- Medicine Design, Pfizer Inc., Cambridge, Massachusetts (J.E.M., A.S.K., Y.W.), and Medicine Design, Pfizer Inc., Groton, Connecticut (K.N., N.J., Z.L., T.C.G.)
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Rudraiah S, Zhang X, Wang L. Nuclear Receptors as Therapeutic Targets in Liver Disease: Are We There Yet? Annu Rev Pharmacol Toxicol 2016; 56:605-626. [PMID: 26738480 DOI: 10.1146/annurev-pharmtox-010715-103209] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Nuclear receptors (NR) are ligand-modulated transcription factors that play diverse roles in cell differentiation, development, proliferation, and metabolism and are associated with numerous liver pathologies such as cancer, steatosis, inflammation, fibrosis, cholestasis, and xenobiotic/drug-induced liver injury. The network of target proteins associated with NRs is extremely complex, comprising coregulators, small noncoding microRNAs, and long noncoding RNAs. The importance of NRs as targets of liver disease is exemplified by the number of NR ligands that are currently used in the clinics or in clinical trials with promising results. Understanding the regulation by NR during pathophysiological conditions, and identifying ligands for orphan NR, points to a potential therapeutic approach for patients with liver diseases. An overview of complex NR metabolic networks and their pharmacological implications in liver disease is presented here.
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Affiliation(s)
- Swetha Rudraiah
- Department of Physiology and Neurobiology and The Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut 06269
| | - Xi Zhang
- Department of Physiology and Neurobiology and The Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut 06269
| | - Li Wang
- Department of Physiology and Neurobiology and The Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut 06269.,Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut 06516.,Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, Connecticut 06520
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14
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Cave MC, Clair HB, Hardesty JE, Falkner KC, Feng W, Clark BJ, Sidey J, Shi H, Aqel BA, McClain CJ, Prough RA. Nuclear receptors and nonalcoholic fatty liver disease. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1083-1099. [PMID: 26962021 DOI: 10.1016/j.bbagrm.2016.03.002] [Citation(s) in RCA: 196] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 02/29/2016] [Accepted: 03/01/2016] [Indexed: 02/08/2023]
Abstract
Nuclear receptors are transcription factors which sense changing environmental or hormonal signals and effect transcriptional changes to regulate core life functions including growth, development, and reproduction. To support this function, following ligand-activation by xenobiotics, members of subfamily 1 nuclear receptors (NR1s) may heterodimerize with the retinoid X receptor (RXR) to regulate transcription of genes involved in energy and xenobiotic metabolism and inflammation. Several of these receptors including the peroxisome proliferator-activated receptors (PPARs), the pregnane and xenobiotic receptor (PXR), the constitutive androstane receptor (CAR), the liver X receptor (LXR) and the farnesoid X receptor (FXR) are key regulators of the gut:liver:adipose axis and serve to coordinate metabolic responses across organ systems between the fed and fasting states. Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease and may progress to cirrhosis and even hepatocellular carcinoma. NAFLD is associated with inappropriate nuclear receptor function and perturbations along the gut:liver:adipose axis including obesity, increased intestinal permeability with systemic inflammation, abnormal hepatic lipid metabolism, and insulin resistance. Environmental chemicals may compound the problem by directly interacting with nuclear receptors leading to metabolic confusion and the inability to differentiate fed from fasting conditions. This review focuses on the impact of nuclear receptors in the pathogenesis and treatment of NAFLD. Clinical trials including PIVENS and FLINT demonstrate that nuclear receptor targeted therapies may lead to the paradoxical dissociation of steatosis, inflammation, fibrosis, insulin resistance, dyslipidemia and obesity. Novel strategies currently under development (including tissue-specific ligands and dual receptor agonists) may be required to separate the beneficial effects of nuclear receptor activation from unwanted metabolic side effects. The impact of nuclear receptor crosstalk in NAFLD is likely to be profound, but requires further elucidation. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.
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Affiliation(s)
- Matthew C Cave
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY 40202, USA; Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA; The Robley Rex Veterans Affairs Medical Center, Louisville, KY 40206, USA; The KentuckyOne Health Jewish Hospital Liver Transplant Program, Louisville, KY 40202, USA.
| | - Heather B Clair
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Josiah E Hardesty
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - K Cameron Falkner
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Wenke Feng
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY 40202, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Barbara J Clark
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Jennifer Sidey
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Hongxue Shi
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Bashar A Aqel
- Department of Medicine, Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Scottsdale, AZ 85054, USA
| | - Craig J McClain
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville School of Medicine, Louisville, KY 40202, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40202, USA; The Robley Rex Veterans Affairs Medical Center, Louisville, KY 40206, USA; The KentuckyOne Health Jewish Hospital Liver Transplant Program, Louisville, KY 40202, USA
| | - Russell A Prough
- Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, KY 40202, USA
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15
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Avouac J, Palumbo-Zerr K, Ruzehaji N, Tomcik M, Zerr P, Dees C, Distler A, Beyer C, Schneider H, Distler O, Schett G, Allanore Y, Distler JHW. The nuclear receptor constitutive androstane receptor/NR1I3 enhances the profibrotic effects of transforming growth factor β and contributes to the development of experimental dermal fibrosis. Arthritis Rheumatol 2015; 66:3140-50. [PMID: 25155144 DOI: 10.1002/art.38819] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 08/05/2014] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Nuclear receptors regulate cell growth, differentiation, and homeostasis. Selective nuclear receptors promote fibroblast activation, which leads to tissue fibrosis, the hallmark of systemic sclerosis (SSc). This study was undertaken to investigate the effects of constitutive androstane receptor (CAR)/NR1I3, an orphan nuclear receptor, on fibroblast activation and experimental dermal fibrosis. METHODS CAR expression was quantified by quantitative polymerase chain reaction, Western blotting, immunohistochemistry, and immunofluorescence. CAR expression was modulated by small molecules, small interfering RNA, forced overexpression, and site-directed mutagenesis. The effects of CAR activation were analyzed in cultured fibroblasts, in bleomycin-induced dermal fibrosis, and in mice overexpressing a constitutively active transforming growth factor β (TGFβ) receptor type I (TβRI-CA). RESULTS Up-regulation of CAR was detected in the skin and in dermal fibroblasts in SSc patients. Stimulation of healthy fibroblasts with TGFβ induced the expression of CAR messenger RNA and protein in a Smad-dependent manner. Pharmacologic activation or overexpression of CAR in healthy fibroblasts significantly increased the stimulatory effects of TGFβ on collagen synthesis and myofibroblast differentiation, and amplified the stimulatory effects of TGFβ on COL1A2 transcription activity. Treatment with CAR agonist increased the activation of canonical TGFβ signaling in murine models of SSc and exacerbated bleomycin-induced and TβRI-CA-induced fibrosis with increased dermal thickening, myofibroblast counts, and collagen accumulation. CONCLUSION Our findings indicate that CAR is up-regulated in SSc and regulates TGFβ signaling. Activation of CAR increases the profibrotic effects of TGFβ in cultured fibroblasts and in different preclinical models of SSc. Thus, inactivation of CAR might be a novel approach to target aberrant TGFβ signaling in SSc and in other fibrotic diseases.
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Affiliation(s)
- Jérôme Avouac
- University of Erlangen-Nuremberg, Erlangen, Germany; Paris Descartes University, INSERM U1016, and Cochin Hospital, AP-HP, Paris, France
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Banerjee M, Robbins D, Chen T. Targeting xenobiotic receptors PXR and CAR in human diseases. Drug Discov Today 2014; 20:618-28. [PMID: 25463033 DOI: 10.1016/j.drudis.2014.11.011] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 10/28/2014] [Accepted: 11/17/2014] [Indexed: 12/20/2022]
Abstract
Nuclear receptors such as the pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are xenobiotic receptors regulating not only drug metabolism and disposition but also various human diseases such as cancer, diabetes, inflammatory disease, metabolic disease and liver diseases, suggesting that PXR and CAR are promising targets for drug discovery. Consequently, there is an urgent need to discover and develop small molecules that target these PXR- and/or CAR-mediated human-disease-related pathways for relevant therapeutic applications. This review proposes approaches to target PXR and CAR, either individually or simultaneously, in the context of various human diseases, taking into consideration the structural differences between PXR and CAR.
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Affiliation(s)
- Monimoy Banerjee
- Department of Chemical Biology and Therapeutics, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Delira Robbins
- Department of Chemical Biology and Therapeutics, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
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17
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Baghdasaryan A, Chiba P, Trauner M. Clinical application of transcriptional activators of bile salt transporters. Mol Aspects Med 2014; 37:57-76. [PMID: 24333169 PMCID: PMC4045202 DOI: 10.1016/j.mam.2013.12.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 11/21/2013] [Accepted: 12/01/2013] [Indexed: 02/07/2023]
Abstract
Hepatobiliary bile salt (BS) transporters are critical determinants of BS homeostasis controlling intracellular concentrations of BSs and their enterohepatic circulation. Genetic or acquired dysfunction of specific transport systems causes intrahepatic and systemic retention of potentially cytotoxic BSs, which, in high concentrations, may disturb integrity of cell membranes and subcellular organelles resulting in cell death, inflammation and fibrosis. Transcriptional regulation of canalicular BS efflux through bile salt export pump (BSEP), basolateral elimination through organic solute transporters alpha and beta (OSTα/OSTβ) as well as inhibition of hepatocellular BS uptake through basolateral Na(+)-taurocholate cotransporting polypeptide (NTCP) represent critical steps in protection from hepatocellular BS overload and can be targeted therapeutically. In this article, we review the potential clinical implications of the major BS transporters BSEP, OSTα/OSTβ and NTCP in the pathogenesis of hereditary and acquired cholestatic syndromes, provide an overview on transcriptional control of these transporters by the key regulatory nuclear receptors and discuss the potential therapeutic role of novel transcriptional activators of BS transporters in cholestasis.
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Affiliation(s)
- Anna Baghdasaryan
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Austria; Laboratory of Experimental and Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, Austria
| | - Peter Chiba
- Institute of Medical Chemistry, Medical University of Vienna, Austria
| | - Michael Trauner
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Austria.
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18
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Shah P, Guo T, Moore DD, Ghose R. Role of constitutive androstane receptor in Toll-like receptor-mediated regulation of gene expression of hepatic drug-metabolizing enzymes and transporters. Drug Metab Dispos 2013; 42:172-81. [PMID: 24194512 DOI: 10.1124/dmd.113.053850] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Impairment of drug disposition in the liver during inflammation has been attributed to downregulation of gene expression of drug-metabolizing enzymes (DMEs) and drug transporters. Inflammatory responses in the liver are primarily mediated by Toll-like receptors (TLRs). We have recently shown that activation of TLR2 or TLR4 by lipoteichoic acid (LTA) and lipopolysaccharide (LPS), respectively, leads to the downregulation of gene expression of DMEs/transporters. However, the molecular mechanism underlying this downregulation is not fully understood. The xenobiotic nuclear receptors, pregnane X receptor (PXR) and constitutive androstane receptor (CAR), regulate the expression of DMEs/transporter genes. Downregulation of DMEs/transporters by LTA or LPS was associated with reduced expression of PXR and CAR genes. To determine the role of CAR, we injected CAR(+/+) and CAR(-/-) mice with LTA or LPS, which significantly downregulated (~40%-60%) RNA levels of the DMEs, cytochrome P450 (Cyp)3a11, Cyp2a4, Cyp2b10, uridine diphosphate glucuronosyltransferase 1a1, amine N-sulfotransferase, and the transporter, multidrug resistance-associated protein 2, in CAR(+/+) mice. Suppression of most of these genes was attenuated in LTA-treated CAR(-/-) mice. In contrast, LPS-mediated downregulation of these genes was not attenuated in CAR(-/-) mice. Induction of these genes by mouse CAR activator 1,4-bis-[2-(3,5-dichloropyridyloxy)]benzene was sustained in LTA- but not in LPS-treated mice. Similar observations were obtained in humanized CAR mice. We have replicated these results in primary hepatocytes as well. Thus, LPS can downregulate DME/transporter genes in the absence of CAR, whereas the effect of LTA on these genes is attenuated in the absence of CAR, indicating the potential involvement of CAR in LTA-mediated downregulation of DME/transporter genes.
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Affiliation(s)
- Pranav Shah
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas (P.S., T.G., R.G.); and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas (D.D.M.)
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The human constitutive androstane receptor promotes the differentiation and maturation of hepatic-like cells. Dev Biol 2013; 384:155-65. [PMID: 24144921 DOI: 10.1016/j.ydbio.2013.10.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 09/11/2013] [Accepted: 10/12/2013] [Indexed: 11/22/2022]
Abstract
Expression of the constitutive androstane receptor (CAR, NR1I3) is enriched in the mature mammalian liver and increasingly recognized for its prominent role in regulating a myriad of processes including biotransformation, chemical transport, energy metabolism and lipid homeostasis. Previously, we demonstrated that CAR levels were markedly enhanced during the differentiation of hepatic-like cells derived from hESCs, prompting the hypothesis that CAR contributes a key functional role in directing human hepatogenesis. Here we demonstrate that over-expression of CAR in human embryonic stem cells (ESCs), transduced by a lentiviral vector, accelerates the maturation of hepatic-like cells, with CAR over-expressing cells exhibiting a 2.5-fold increase in albumin secretion by day 20 in culture differentiation, and significantly enhanced levels of mRNA expression of several liver-selective markers, including hepatic transcription factors, plasma proteins, biotransformation enzymes, and metabolic enzymes. CAR over-expressing cells also exhibited enhanced CITCO-inducible CYP3A7 enzymatic activity. Knockdown of CAR via siRNA attenuated the differentiation-dependent expression programs. In contrast, expression levels of the pregnane X receptor (PXR), a nuclear receptor most similar to CAR in primary sequence, were negligible in human fetal liver tissues or in the differentiating hESCs, and stable over-expression of PXR in hepatic-induced hESCs failed to enhance expression of hepatic phenotype markers. Together, these results define a novel role for human CAR in hepatic lineage commitment.
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20
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miR-137 regulates the constitutive androstane receptor and modulates doxorubicin sensitivity in parental and doxorubicin-resistant neuroblastoma cells. Oncogene 2013; 33:3717-29. [PMID: 23934188 DOI: 10.1038/onc.2013.330] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 06/14/2013] [Accepted: 06/28/2013] [Indexed: 12/31/2022]
Abstract
Chemotherapy is the most common treatment for cancer. However, multidrug resistance (MDR) remains a major obstacle to effective chemotherapy, limiting the efficacy of both conventional chemotherapeutic and novel biologic agents. The constitutive androstane receptor (CAR), a xenosensor, is a key regulator of MDR. It functions in xenobiotic detoxification by regulating the expression of phase I drug-metabolizing enzymes and ATP-binding cassette (ABC) transporters, whose overexpression in cancers and whose role in drug resistance make them potential therapeutic targets for reducing MDR. MicroRNAs (miRNAs) are endogenous negative regulators of gene expression and have been implicated in most cellular processes, including drug resistance. Here, we report the inversely related expression of miR-137 and CAR in parental and doxorubicin-resistant neuroblastoma cells, wherein miR-137 is downregulated in resistant cells. miR-137 overexpression resulted in downregulation of CAR protein and mRNA (via mRNA degradation); it sensitized doxorubicin-resistant cells to doxorubicin (as shown by reduced proliferation, increased apoptosis and increased G2-phase cell cycle arrest) and reduced the in vivo growth rate of neuroblastoma xenografts. We observed similar results in cellular models of hepatocellular and colon cancers, indicating that the doxorubicin-sensitizing effect of miR-137 is not tumor type-specific. Finally, we show for the first time a negative feedback loop whereby miR-137 downregulates CAR expression and CAR downregulates miR-137 expression. Hypermethylation of the miR-137 promoter and negative regulation of miR-137 by CAR contribute in part to reduced miR-137 expression and increased CAR and MDR1 expression in doxorubicin-resistant neuroblastoma cells. These findings demonstrate that miR-137 is a crucial regulator of cancer response to doxorubicin treatment, and they identify miR-137 as a highly promising target to reduce CAR-driven doxorubicin resistance.
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Gadd45 in the Liver: Signal Transduction and Transcriptional Mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 793:69-80. [DOI: 10.1007/978-1-4614-8289-5_5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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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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Chen WD, Fu X, Dong B, Wang YD, Shiah S, Moore DD, Huang W. Neonatal activation of the nuclear receptor CAR results in epigenetic memory and permanent change of drug metabolism in mouse liver. Hepatology 2012; 56:1499-509. [PMID: 22488010 PMCID: PMC3407349 DOI: 10.1002/hep.25766] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
UNLABELLED Aberrant epigenetic alterations during development may result in long-term epigenetic memory and have a permanent effect on the health of subjects. Constitutive androstane receptor (CAR) is a central regulator of drug/xenobiotic metabolism. Here, we report that transient neonatal activation of CAR results in epigenetic memory and a permanent change of liver drug metabolism. CAR activation by neonatal exposure to the CAR-specific ligand 1,4-bis[2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP) led to persistently induced expression of the CAR target genes Cyp2B10 and Cyp2C37 throughout the life of exposed mice. These mice showed a permanent reduction in sensitivity to zoxazolamine treatment as adults. Compared with control groups, the induction of Cyp2B10 and Cyp2C37 in hepatocytes isolated from these mice was more sensitive to low concentrations of the CAR agonist TCPOBOP. Accordingly, neonatal activation of CAR led to a permanent increase of histone 3 lysine 4 mono-, di-, and trimethylation and decrease of H3K9 trimethylation within the Cyp2B10 locus. Transcriptional coactivator activating signal cointegrator-2 and histone demethylase JMJD2d participated in this CAR-dependent epigenetic switch. CONCLUSION Neonatal activation of CAR results in epigenetic memory and a permanent change of liver drug metabolism.
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Affiliation(s)
- Wei-Dong Chen
- Division of Gene Regulation & Drug Discovery, Beckman Research Institute, City of Hope National Medical Center, 1500 E. Duarte Road, Duarte, CA 91010,School of Medicine, Henan University, Kaifeng 475001, P. R. China
| | - Xianghui Fu
- Division of Gene Regulation & Drug Discovery, Beckman Research Institute, City of Hope National Medical Center, 1500 E. Duarte Road, Duarte, CA 91010
| | - Bingning Dong
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030
| | - Yan-Dong Wang
- Division of Gene Regulation & Drug Discovery, Beckman Research Institute, City of Hope National Medical Center, 1500 E. Duarte Road, Duarte, CA 91010,Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio 44272
| | - Steven Shiah
- Division of Gene Regulation & Drug Discovery, Beckman Research Institute, City of Hope National Medical Center, 1500 E. Duarte Road, Duarte, CA 91010
| | - David D. Moore
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030
| | - Wendong Huang
- Division of Gene Regulation & Drug Discovery, Beckman Research Institute, City of Hope National Medical Center, 1500 E. Duarte Road, Duarte, CA 91010
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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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Jiang JX, Chen X, Serizawa N, Szyndralewiez C, Page P, Schröder K, Brandes RP, Devaraj S, Török NJ. Liver fibrosis and hepatocyte apoptosis are attenuated by GKT137831, a novel NOX4/NOX1 inhibitor in vivo. Free Radic Biol Med 2012; 53:289-96. [PMID: 22618020 PMCID: PMC3392471 DOI: 10.1016/j.freeradbiomed.2012.05.007] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 04/23/2012] [Accepted: 05/03/2012] [Indexed: 12/13/2022]
Abstract
Reactive oxygen species (ROS) play a key role in chronic liver injury and fibrosis. Homologs of NADPH oxidases (NOXs) are major sources of ROS, but the exact role of the individual homologs in liver disease is unknown. Our goal was to determine the role of NOX4 in liver fibrosis induced by bile duct ligation (BDL) with the aid of the pharmacological inhibitor GKT137831, and genetic deletion of NOX4 in mice. GKT137831 was either applied for the full term of BDL (preventive arm) or started at 10 day postoperatively (therapeutic arm). Primary hepatic stellate cells (HSC) from control mice with and without BDL were analyzed and the effect of NOX4 inhibition on HSC activation was also studied. FasL or TNFα/actinomycin D-induced apoptosis was studied in wild-type and NOX4(-/-) hepatocytes. NOX4 was upregulated by a TGF-β/Smad3-dependent mechanism in HSC. Downregulation of NOX4 decreased ROS production and the activation of NOX4(-/-) HSC was attenuated. NOX4(-/-) hepatocytes were more resistant to FasL or TNFα/actinomycin D-induced apoptosis. Similarly, after pharmacological NOX4 inhibition, ROS production, the expression of fibrogenic markers, and hepatocyte apoptosis were reduced. NOX4 was expressed in human livers with stage 2-3 autoimmune hepatitis. Fibrosis was attenuated by the genetic deletion of NOX4. BDL mice gavaged with GKT137831 in the preventive or the therapeutic arm displayed less ROS production, significantly attenuated fibrosis, and decreased hepatocyte apoptosis. In conclusion, NOX4 plays a key role in liver fibrosis. GKT137831 is a potent inhibitor of fibrosis and hepatocyte apoptosis; therefore, it is a promising therapeutic agent for future translational studies.
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Affiliation(s)
- Joy X Jiang
- Department of Internal Medicine, UC Davis, Sacramento, CA, USA
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Tian J, Huang H, Hoffman B, Liebermann DA, Ledda-Columbano GM, Columbano A, Locker J. Gadd45β is an inducible coactivator of transcription that facilitates rapid liver growth in mice. J Clin Invest 2011; 121:4491-502. [PMID: 21965327 DOI: 10.1172/jci38760] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 08/24/2011] [Indexed: 12/16/2022] Open
Abstract
The growth arrest and DNA damage-inducible 45 (Gadd45) proteins act in many cellular processes. In the liver, Gadd45b (encoding Gadd45β) is the gene most strongly induced early during both compensatory regeneration and drug-induced hyperplasia. The latter response is associated with the dramatic and rapid hepatocyte growth that follows administration of the xenobiotic TCPOBOP (1,4-bis[2-(3,5)-dichoropyridyloxy] benzene), a ligand of the nuclear receptor constitutive androstane receptor (CAR). Here, we have shown that Gadd45b-/- mice have intact proliferative responses following administration of a single dose of TCPOBOP, but marked growth delays. Moreover, early transcriptional stimulation of CAR target genes was weaker in Gadd45b-/- mice than in wild-type animals, and more genes were downregulated. Gadd45β was then found to have a direct role in transcription by physically binding to CAR, and TCPOBOP treatment caused both proteins to localize to a regulatory element for the CAR target gene cytochrome P450 2b10 (Cyp2b10). Further analysis defined separate Gadd45β domains that mediated binding to CAR and transcriptional activation. Although baseline hepatic expression of Gadd45b was broadly comparable to that of other coactivators, its 140-fold stimulation by TCPOBOP was striking and unique. The induction of Gadd45β is therefore a response that facilitates increased transcription, allowing rapid expansion of liver mass for protection against xenobiotic insults.
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Affiliation(s)
- Jianmin Tian
- Department of Pathology and Marion Bessin Liver Center, Albert Einstein College of Medicine, New York, New York, USA
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Chen X, Meng Z, Wang X, Zeng S, Huang W. The nuclear receptor CAR modulates alcohol-induced liver injury. J Transl Med 2011; 91:1136-45. [PMID: 21519326 DOI: 10.1038/labinvest.2011.68] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The constitutive androstane receptor (CAR) is a member of the nuclear receptor superfamily and a sensor and detoxifier of both xenobiotics and endobiotics. Recent studies also show that CAR participates in metabolism of glucose and lipid, and has an important role in fatty liver disease and diabetes. In this study, we investigate the roles of CAR in chronic and acute alcohol-induced liver injuries. The results showed that absence of CAR in rodents led to significantly increased susceptibility to chronic alcohol-induced liver injury, which was accompanied with elevated hepatocyte apoptosis and fat accumulation. However, pre-activation of CAR by a CAR agonist, TCPOBOP, strongly enhanced the hepatic toxicity by both chronic and acute alcohol infusion in wild-type, but not in CAR(-/-) mice. Gene expression analyses indicated that CAR pre-activation and alcohol infusion synergistically decreased the expression of enzymes that metabolize the alcohol in liver. These results support a role of CAR in modulating alcoholic liver injury and imply a risk of synergistic liver toxicity induced by alcohol and CAR activation.
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Affiliation(s)
- Xiaosong Chen
- Division of Gene Regulation and Drug Discovery, City of Hope National Medical Center, Duarte, CA, USA
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Inorganic arsenic causes cell apoptosis in mouse cerebrum through an oxidative stress-regulated signaling pathway. Arch Toxicol 2011; 85:565-75. [DOI: 10.1007/s00204-011-0709-y] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 04/12/2011] [Indexed: 10/18/2022]
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De Minicis S, Svegliati-Baroni G. Fibrogenesis in nonalcoholic steatohepatitis. Expert Rev Gastroenterol Hepatol 2011; 5:179-87. [PMID: 21476913 DOI: 10.1586/egh.11.28] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Nonalcoholic steatohepatitis includes a wide spectrum of liver injury, ranging from simple inflammation to fibrosis and cirrhosis. Whereas simple steatosis has a benign clinical course, steatohepatitis is a recognized cause of progressive liver fibrosis and can develop, in some circumstances, into cirrhosis. The main cause of fibrogenesis is represented by the activation of myofibroblastic cells, which then start to produce matrix filaments. Matrix-producing cells, although mainly constituted of hepatic stellate cells, may have a different origin in the liver. This article will provide information on the sources of matrix-producing cells and the mechanisms involved in the development of fibrogenesis, with particular attention paid to the pathophysiological implications leading from steatohepatitis to fibrosis and cirrhosis.
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Affiliation(s)
- Samuele De Minicis
- Department of Gastroenterology, Polytechnic University of Marche, Ancona, Italy
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Constitutive androstane receptor agonist CITCO inhibits growth and expansion of brain tumour stem cells. Br J Cancer 2011; 104:448-59. [PMID: 21224854 PMCID: PMC3049563 DOI: 10.1038/sj.bjc.6606064] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Background: Brain tumours present unique challenges to conventional therapies and pose major health problems around the world. Brain tumour stem cells (BTSCs) represent a small fraction of tumour cells that maintain growth, drug resistance and recurrence properties. Constitutive androstane receptor (CAR) is a nuclear receptor transcription factor that regulates drug metabolism and homoeostasis. In this study, we examined the effect of CAR agonist, 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehydeO-(3,4-dichlorobenzyl)oxime (CITCO) on BTSCs. Methods: The expression of CAR in BTSCs was detected by quantitative RT–PCR and western blot. The antiproliferative effect of CITCO on BTSCs was determined by WST-1 and 3H thymidine uptake assays. The effect of CITCO on CD133 expression, cell cycle progression and apoptosis in BTSCs was analysed by immunostaining and flow cytometry. The in vivo effect of CITCO was studied using subcutaneous (s.c.) BTSC xenograft in nude mice. Results: We show for the first time that BTSCs express altered levels of nuclear receptors compared with glioma cells. The expression of CAR mRNA and protein was low in BTSCs and that increased following treatment with CITCO in culture. CITCO induced a dose-dependent decrease in growth and expansion of CD133+ BTSCs as gliospheres in culture. Cell cycle arrest and apoptosis in BTSCs were induced by CITCO, but not in normal astrocytes. Growth of s.c BTSC xenograft in nude mice was also inhibited by CITCO. Conclusion: These findings indicate that CITCO inhibits the growth and expansion of BTSCs, suggesting the use of CAR agonists for the treatment of brain tumour.
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Takizawa D, Kakizaki S, Horiguchi N, Yamazaki Y, Tojima H, Mori M. Constitutive active/androstane receptor promotes hepatocarcinogenesis in a mouse model of non-alcoholic steatohepatitis. Carcinogenesis 2010; 32:576-83. [PMID: 21173431 DOI: 10.1093/carcin/bgq277] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The nuclear receptor constitutive active/androstane receptor (CAR) acts as a sensor of toxic byproducts derived from the endogenous metabolism and exogenous chemicals. We previously reported that CAR is responsible for exacerbating hepatic injury and fibrosis in a dietary model of non-alcoholic steatohepatitis (NASH) via upregulation of lipid peroxidation. In this study, we investigated the pathological roles of the CAR in the development of hepatocellular carcinoma in NASH model. CAR+/+ and CAR-/- mice were fed methionine- and choline-deficient (MCD) diet after tumor initiation with a single dose of the genotoxic carcinogen diethylnitrosamine (DEN) at 2 weeks of age. Interestingly, the MCD diet dramatically promoted DEN-induced hepatocarcinogenesis in CAR+/+ mice. However, the deletion of CAR leads to a significantly lower tumor incidence and smaller tumor diameter. Hepatocytes of MCD-treated-CAR+/+ mice showed a significantly higher staining frequency of Ki-67, a marker of cell proliferation, and exhibited a higher expression of c-Myc and FoxM1 transcripts compared with MCD-treated CAR-/- mice. Immunohistochemistry revealed the nuclear translocation of CAR thus suggesting that the activation of CAR signaling increased in the hepatocytes of CAR+/+ mice fed MCD diet. In addition, in vitro experiments using the CAR stably expressed cell line with TCPOBOP have suggested that CAR activation directly leads to cell proliferation. Survival was significantly lower in the CAR+/+ mice fed the MCD diet in comparison with the CAR-/- mice. Taken together, these results suggest that CAR may therefore play a critical role in the hepatocarcinogenesis of the murine NASH model via the upregulation of cell proliferation.
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Affiliation(s)
- Daichi Takizawa
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma 371-8511, Japan
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Fukumasu H, Sanches DS, da Silva TC, Ward JM, Dagli MLZ. Transient disruption of liver gap junctional intercellular communication and induction of apoptosis after administration of 1,4-bis[2-(3,5 dichloropyridyloxy)]benzene in mice. EXPERIMENTAL AND TOXICOLOGIC PATHOLOGY : OFFICIAL JOURNAL OF THE GESELLSCHAFT FUR TOXIKOLOGISCHE PATHOLOGIE 2010; 62:525-31. [PMID: 19651500 DOI: 10.1016/j.etp.2009.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 07/03/2009] [Indexed: 10/20/2022]
Abstract
Gap junctional intercellular communication (GJIC) and connexin expression (Cx26 and Cx32) in mouse liver were studied after administration of 4-bis[2-(3,5 dichloropyridyloxy)]benzene (TCPOBOP), a phenobarbital-like enzyme inducer. Female C57Bl/6 mice were administered TCPOBOP (5.8 mg/kg BW) and euthanized 0, 24, 48 and 72 hours later. Liver samples were snap frozen, or fixed in formalin, or submitted to GJIC analysis. The proliferating cell nuclear antigen (PCNA) immunohistochemistry and the Western blotting for Cx26 and Cx32 were performed. After 48 and 72 h of drug administration the liver-to-body weight ratio was increased 70% and 117% (p<0.0001), respectively. There were temporal-dependent alterations in liver histopathology and a significant increase in cell proliferation was noted after 48 h and sustained after 72 h, though to a lesser extent (p<0.0001). In addition, TCPOBOP administration induced apoptosis, which appeared to be time-dependent showing statistical significance only after 72 h (p<0.0001). Interestingly, a transient disruption by nearly 50% of GJIC capacity was detected after 48 h of drug ingestion, which recovered after 72 h (p=0.003). These GJIC changes were due to altered levels of Cx26 and Cx32 in the livers of TCPOBOP-treated mice. We concluded that a single administration of TCPOBOP transiently disrupted the levels of GJIC due to decreased expression of connexins and increased apoptotic cell death in mouse liver.
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Affiliation(s)
- Heidge Fukumasu
- Laboratory of Experimental and Comparative Oncology, School of Veterinary Medicine and Animal Sciences, University of Sao Paulo, Sao Paulo, Brazil
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Hikita H, Takehara T, Shimizu S, Kodama T, Li W, Miyagi T, Hosui A, Ishida H, Ohkawa K, Kanto T, Hiramatsu N, Yin XM, Hennighausen L, Tatsumi T, Hayashi N. Mcl-1 and Bcl-xL cooperatively maintain integrity of hepatocytes in developing and adult murine liver. Hepatology 2009; 50:1217-26. [PMID: 19676108 PMCID: PMC3560852 DOI: 10.1002/hep.23126] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
UNLABELLED Anti-apoptotic members of the Bcl-2 family, including Bcl-2, Bcl-xL, Mcl-1, Bcl-w and Bfl-1, inhibit the mitochondrial pathway of apoptosis. Bcl-xL and Mcl-1 are constitutively expressed in the liver. Although previous research established Bcl-xL as a critical apoptosis antagonist in differentiated hepatocytes, the significance of Mcl-1 in the liver, especially in conjunction with Bcl-xL, has not been clear. To examine this question, we generated hepatocyte-specific Mcl-1-deficient mice by crossing mcl-1(flox/flox) mice and AlbCre mice and further crossed them with bcl-x(flox/flox) mice, giving Mcl-1/Bcl-xL-deficient mice. The mcl-1(flox/flox) AlbCre mice showed spontaneous apoptosis of hepatocytes after birth, as evidenced by elevated levels of serum alanine aminotransferase (ALT) and caspase-3/7 activity and an increased number of terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick-end labeling (TUNEL)-positive cells in the liver; these phenotypes were very close to those previously found in hepatocyte-specific Bcl-xL-deficient mice. Although mcl-1(flox/+) AlbCre mice did not display apoptosis, their susceptibility to Fas-mediated liver injury significantly increased. Further crossing of Mcl-1 mice with Bcl-xL mice showed that bcl-x(flox/+) mcl-1(flox/+) AlbCre mice also showed spontaneous hepatocyte apoptosis similar to Bcl-xL-deficient or Mcl-1-deficient mice. In contrast, bcl-x(flox/flox) mcl-1(flox/+) AlbCre, bcl-x(flox/+) mcl-1(flox/flox) AlbCre, and bcl-x(flox/flox) mcl-1(flox/flox) AlbCre mice displayed a decreased number of hepatocytes and a reduced volume of the liver on day 18.5 of embryogenesis and rapidly died within 1 day after birth, developing hepatic failure evidenced by increased levels of blood ammonia and bilirubin. CONCLUSION Mcl-1 is critical for blocking apoptosis in adult liver and, in the absence of Bcl-xL, is essential for normal liver development. Mcl-1 and Bcl-xL are two major anti-apoptotic Bcl-2 family proteins expressed in the liver and cooperatively control hepatic integrity during liver development and in adult liver homeostasis in a gene dose-dependent manner.
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Affiliation(s)
- Hayato Hikita
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Tetsuo Takehara
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Satoshi Shimizu
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Takahiro Kodama
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Wei Li
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Takuya Miyagi
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Atsushi Hosui
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hisashi Ishida
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Kazuyoshi Ohkawa
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Tatsuya Kanto
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Naoki Hiramatsu
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Xiao-Ming Yin
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Lothar Hennighausen
- Laboratory of Genetics and Physiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Tomohide Tatsumi
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Norio Hayashi
- Department of Gastroenterology and Hepatology, Osaka University Graduate School of Medicine, Osaka, Japan
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Kahraman A, Mott JL, Bronk SF, Werneburg NW, Barreyro FJ, Guicciardi ME, Akazawa Y, Braley K, Craig RW, Gores GJ. Overexpression of mcl-1 attenuates liver injury and fibrosis in the bile duct-ligated mouse. Dig Dis Sci 2009; 54:1908-17. [PMID: 19051025 PMCID: PMC2879585 DOI: 10.1007/s10620-008-0583-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 10/13/2008] [Indexed: 02/07/2023]
Abstract
Hepatocyte apoptosis contributes to liver injury and fibrosis after cholestatic injury. Our aim was to ascertain if the anti-apoptotic protein Mcl-1 alters liver injury or fibrosis in the bile duct-ligated mouse. Markers of apoptosis and fibrosis were compared in wild-type and transgenic mice expressing human Mcl-1 after bile duct ligation. Compared to hMcl-1 transgenic animals, ligated wild-type mice displayed a significant increase in TUNEL-positive cells and in caspase 3/7-positive hepatocytes. Consistent with apoptotic injury, the pro-apoptotic protein Bak underwent a conformational change to an activated form upon cholestatic injury, a change mitigated by hMcl-1 overexpression. Likewise, liver histology, number of bile infarcts, serum ALT values, markers of hepatic fibrosis, and animal survival were improved in bile duct-ligated mice transgenic for hMcl-1 as compared to wild-type mice. In conclusion, increased Mcl-1 expression plays a role in hepatoprotection upon cholestatic liver injury.
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Affiliation(s)
- Alisan Kahraman
- Division of Gastroenterology and Hepatology, Miles and Shirley, Fiterman Center for Digestive Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA,Department of Gastroenterology and Hepatology, University Clinic Essen, 45122 Essen, Germany
| | - Justin L. Mott
- Division of Gastroenterology and Hepatology, Miles and Shirley Fiterman Center for Digestive Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
| | - Steven F. Bronk
- Division of Gastroenterology and Hepatology, Miles and Shirley, Fiterman Center for Digestive Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
| | - Nathan W. Werneburg
- Division of Gastroenterology and Hepatology, Miles and Shirley, Fiterman Center for Digestive Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
| | - Fernando J. Barreyro
- Division of Gastroenterology and Hepatology, Miles and Shirley, Fiterman Center for Digestive Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
| | - Maria E. Guicciardi
- Division of Gastroenterology and Hepatology, Miles and Shirley, Fiterman Center for Digestive Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
| | - Yuko Akazawa
- Division of Gastroenterology and Hepatology, Miles and Shirley, Fiterman Center for Digestive Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
| | - Karen Braley
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH 03755-3835, USA
| | - Ruth W. Craig
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH 03755-3835, USA
| | - Gregory J. Gores
- Division of Gastroenterology and Hepatology, Miles and Shirley, Fiterman Center for Digestive Diseases, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA
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Hernandez J, Mota L, Baldwin W. Activation of CAR and PXR by Dietary, Environmental and Occupational Chemicals Alters Drug Metabolism, Intermediary Metabolism, and Cell Proliferation. CURRENT PHARMACOGENOMICS AND PERSONALIZED MEDICINE 2009; 7:81-105. [PMID: 20871735 PMCID: PMC2944248 DOI: 10.2174/187569209788654005] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The constitutive androstane receptor (CAR) and the pregnane × receptor (PXR) are activated by a variety of endogenous and exogenous ligands, such as steroid hormones, bile acids, pharmaceuticals, and environmental, dietary, and occupational chemicals. In turn, they induce phase I-III detoxification enzymes and transporters that help eliminate these chemicals. Because many of the chemicals that activate CAR and PXR are environmentally-relevant (dietary and anthropogenic), studies need to address whether these chemicals or mixtures of these chemicals may increase the susceptibility to adverse drug interactions. In addition, CAR and PXR are involved in hepatic proliferation, intermediary metabolism, and protection from cholestasis. Therefore, activation of CAR and PXR may have a wide variety of implications for personalized medicine through physiological effects on metabolism and cell proliferation; some beneficial and others adverse. Identifying the chemicals that activate these promiscuous nuclear receptors and understanding how these chemicals may act in concert will help us predict adverse drug reactions (ADRs), predict cholestasis and steatosis, and regulate intermediary metabolism. This review summarizes the available data on CAR and PXR, including the environmental chemicals that activate these receptors, the genes they control, and the physiological processes that are perturbed or depend on CAR and PXR action. This knowledge contributes to a foundation that will be necessary to discern interindividual differences in the downstream biological pathways regulated by these key nuclear receptors.
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Affiliation(s)
- J.P. Hernandez
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - L.C. Mota
- Institute of Environmental Toxicology, Clemson University, Pendleton, SC, USA
| | - W.S. Baldwin
- Institute of Environmental Toxicology, Clemson University, Pendleton, SC, USA
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Kodama Y, Taura K, Miura K, Schnabl B, Osawa Y, Brenner DA. Antiapoptotic effect of c-Jun N-terminal Kinase-1 through Mcl-1 stabilization in TNF-induced hepatocyte apoptosis. Gastroenterology 2009; 136:1423-34. [PMID: 19249395 DOI: 10.1053/j.gastro.2008.12.064] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Revised: 12/02/2008] [Accepted: 12/29/2008] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS c-Jun N-terminal Kinase (JNK) is a key regulator in tumor necrosis factor (TNF)-mediated liver injury. However, distinct roles for JNK1 and JNK2 in hepatocyte apoptosis are still unresolved. Although myeloid cell leukemia-1 (Mcl-1) has been reported as a substrate of JNK, the role of Mcl-1 and its functional regulation by JNK in TNF-induced hepatocyte apoptosis and liver injury remain to be elucidated. METHODS TNF-induced hepatocyte apoptosis was investigated in wild-type, jnk1-/- and jnk2-/- mice in vitro and in the galactosamine/TNF (GalN/TNF) liver injury model. For further analysis, we used adenoviruses expressing wild-type Mcl-1 or its substitution mutant, and the Cre/loxP system (mcl-1f/f) to delete mcl-1. RESULTS jnk2-/- Hepatocytes showed increased Mcl-1 expression and were more resistant to TNF-induced apoptosis compared with wild-type or jnk1-/- hepatocytes. Increased Mcl-1 expression in jnk2-/- hepatocytes correlated with their JNK activity, which is mediated by residual JNK1 and higher than in wild-type or jnk1-/- hepatocytes. JNK activation led to phosphorylation of Mcl-1 in hepatocytes, and this increased the half-life of the Mcl-1 protein. Overexpression of Mcl-1 confirmed its antiapoptotic effect in TNF-induced hepatocyte apoptosis in vitro and in vivo. Deletion of mcl-1 in jnk2-/- hepatocytes increased TNF-induced hepatocyte apoptosis both in vitro and in GalN/TNF-induced liver injury model. CONCLUSIONS jnk2-/- Hepatocytes are resistant to TNF-induced apoptosis. Activated JNK1 contributes to this antiapoptotic phenotype of jnk2-/- hepatocytes through phosphorylation-mediated stabilization of Mcl-1.
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Affiliation(s)
- Yuzo Kodama
- Department of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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Beilke LD, Aleksunes LM, Olson ER, Besselsen DG, Klaassen CD, Dvorak K, Cherrington NJ. Decreased apoptosis during CAR-mediated hepatoprotection against lithocholic acid-induced liver injury in mice. Toxicol Lett 2009; 188:38-44. [PMID: 19433268 DOI: 10.1016/j.toxlet.2009.03.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 03/05/2009] [Accepted: 03/06/2009] [Indexed: 01/14/2023]
Abstract
Myeloid cell leukemia-1 (Mcl-1) is an anti-apoptotic protein that is regulated by the constitutive androstane receptor (CAR). Activation of CAR can protect the liver against bile acid-induced toxicity and it may have a role in cell death via apoptosis by altering expression of Bcl-2 family proteins such as myeloid cell leukemia-1 (Mcl-1). Our aim was to determine if activation of CAR reduces hepatocellular apoptosis during cholestasis as a mechanism of hepatoprotection. CAR(+/+) (WT) and CAR(-/-) (CAR-null) mice were pre-treated with compounds known to activate CAR prior to induction of intrahepatic cholestasis using the secondary bile acid lithocholic acid (LCA). Pre-treatment with the CAR activators phenobarbital (PB) and TCPOBOP (TC), as well as the non-CAR activator pregnenolone 16alpha-carbontrile (PCN), protected against LCA-induced liver injury in WT mice, whereas liver injury was more extensive without CAR (CAR-null). Unexpectedly, expression of anti-apoptotic Mcl-1 and Bcl-x(L) was not increased in hepatoprotected mice. Compared to unprotected groups, apoptosis was decreased in hepatoprotected mice as evidenced by the absence of cleaved caspase 3 (cCasp3). In contrast to the cytoplasmic localization in the injured livers (LCA and oltipraz), Mcl-1 protein was localized in the nucleus of hepatoprotected livers to potentially promote cell survival. This study demonstrates that although apoptosis is reduced in hepatoprotected mice pre-treated with CAR and non-CAR activators; hepatoprotection is not directly a result of CAR-induced Mcl-1 expression.
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Affiliation(s)
- Lisa D Beilke
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ 85721, USA
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Vick B, Weber A, Urbanik T, Maass T, Teufel A, Krammer PH, Opferman JT, Schuchmann M, Galle PR, Schulze-Bergkamen H. Knockout of myeloid cell leukemia-1 induces liver damage and increases apoptosis susceptibility of murine hepatocytes. Hepatology 2009; 49:627-36. [PMID: 19127517 PMCID: PMC2753874 DOI: 10.1002/hep.22664] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
UNLABELLED Myeloid cell leukemia-1 (Mcl-1) is an antiapoptotic member of the Bcl-2 protein family. It interacts with proapoptotic Bcl-2 family members, thereby inhibiting mitochondrial activation and induction of apoptosis. Mcl-1 is essential for embryonal development and the maintenance of B cells, T cells, and hematopoietic stem cells. We have recently shown that induction of Mcl-1 by growth factors rescues primary human hepatocytes from CD95-mediated apoptosis. This prompted us to further analyze the relevance of Mcl-1 for hepatocellular homeostasis. Therefore, we generated a hepatocyte-specific Mcl-1 knockout mouse (Mcl-1(flox/flox)-AlbCre). Deletion of Mcl-1 in hepatocytes results in liver cell damage caused by spontaneous induction of apoptosis. Livers of Mcl-1(flox/flox)-AlbCre mice are smaller compared to control littermates, due to higher apoptosis rates. As a compensatory mechanism, proliferation of hepatocytes is enhanced in the absence of Mcl-1. Importantly, hepatic pericellular fibrosis occurs in Mcl-1 negative livers in response to chronic liver damage. Furthermore, Mcl-1(flox/flox)-AlbCre mice are more susceptible to hepatocellular damage induced by agonistic anti-CD95 antibodies or concanavalin A. CONCLUSION The present study provides in vivo evidence that Mcl-1 is a crucial antiapoptotic factor for the liver, contributing to hepatocellular homeostasis and protecting hepatocytes from apoptosis induction.
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Affiliation(s)
- Binje Vick
- 1 Department of Medicine, Johannes Gutenberg-University Mainz, Germany
| | - Achim Weber
- Department of Pathology, Institute of Surgical Pathology, University Hospital, Zurich, Switzerland
| | - Toni Urbanik
- 1 Department of Medicine, Johannes Gutenberg-University Mainz, Germany
| | - Thorsten Maass
- 1 Department of Medicine, Johannes Gutenberg-University Mainz, Germany
| | - Andreas Teufel
- 1 Department of Medicine, Johannes Gutenberg-University Mainz, Germany
| | - Peter H. Krammer
- German Cancer Research Center, Tumor Immunology Program, Heidelberg, Germany
| | - Joseph T. Opferman
- Department of Biochemistry, St. Jude Children’s Research Hospital, Memphis, USA
| | - Marcus Schuchmann
- 1 Department of Medicine, Johannes Gutenberg-University Mainz, Germany
| | - Peter R. Galle
- 1 Department of Medicine, Johannes Gutenberg-University Mainz, Germany
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Wang YD, Yang F, Chen WD, Huang X, Lai L, Forman BM, Huang W. Farnesoid X receptor protects liver cells from apoptosis induced by serum deprivation in vitro and fasting in vivo. Mol Endocrinol 2008; 22:1622-32. [PMID: 18436567 DOI: 10.1210/me.2007-0527] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The farnesoid X receptor (FXR) is a key metabolic regulator in the liver by maintaining the homeostasis of liver metabolites. Recent findings suggest that FXR may have a much broader function in liver physiology and pathology. In the present work, we identify a novel role of FXR in protecting liver cell from apoptosis induced by nutritional withdrawal including serum deprivation in vitro or starvation in vivo. Two FXR ligands, chenodeoxycholic acid (CDCA) and GW4064, rescued HepG2 cells from serum deprivation-induced apoptosis in a dose-dependent manner. This effect of FXR on apoptotic suppression was compromised when FXR was knocked down by short interfering RNA. Similarly, the effects of both CDCA and GW4064 were abolished after inhibition of the MAPK pathway by a specific inhibitor of MAPK kinase 1/2. Immunoblotting results indicated that FXR activation by CDCA and GW4064 induced ERK1/2 phosphorylation, which was attenuated by serum deprivation. In vivo, FXR(-/-) mice exhibited an exacerbated liver apoptosis and lower levels of phosphorylated-ERK1/2 compared to wild-type mice after starvation. In conclusion, our results suggest a novel role of FXR in modulating liver cell apoptosis.
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Affiliation(s)
- Yan-Dong Wang
- Department of Gene Regulation and Drug Discovery, Beckman Research Institute of City of Hope National Medical Center, Duarte, CA 91010, USA
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Takahashi T, Moriyama Y, Ikari A, Sugatani J, Suzuki T, Miwa M. Surface localization of the nuclear receptor CAR in influenza A virus-infected cells. Biochem Biophys Res Commun 2008; 368:550-5. [DOI: 10.1016/j.bbrc.2008.01.145] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 01/18/2008] [Indexed: 11/25/2022]
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Abstract
The constitutive androstane receptor (CAR), a member of the NR1I group of nuclear hormone receptors, has been implicated in regulating the expression of genes that are critical in xenobiotic and endobiotic metabolism, uptake and elimination as well as genes involved in various other physiological processes. Hence, functional variation in CAR associated with its expression and/or activity can influence the transcriptional activation of its target genes and could contribute to the observed variation in drug response and toxicity. Moreover, coadministration of agents that are also CAR activators contributes to clinically relevant drug-drug interactions in patients receiving certain combination therapies. This review will discuss the functional significance of known genetic variants in CAR and the most common alternatively spliced isoforms of CAR. We will also discuss the influence of gender and ethnicity on CAR and its target genes. Although genetic polymorphisms in CAR may have an indirect effect on drug disposition, understanding the association of genetic polymorphisms in CAR with the expression of its target genes might help us to better understand the molecular mechanisms underlying the interindividual variation in drug disposition in addition to drug-drug interactions.
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Affiliation(s)
- Jatinder K Lamba
- St Jude Children's Research Hospital, Department of Pharmaceutical Sciences, 332 North Lauderdale Street, Memphis, TN 38105, USA.
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Baskin-Bey ES, Anan A, Isomoto H, Bronk SF, Gores GJ. Constitutive androstane receptor agonist, TCPOBOP, attenuates steatohepatitis in the methionine choline-deficient diet-fed mouse. World J Gastroenterol 2007; 13:5635-41. [PMID: 17948939 PMCID: PMC4172744 DOI: 10.3748/wjg.v13.i42.5635] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To ascertain whether constitutive androstane receptor (CAR) activation by 1,4-bis-[2-(3,5,-dichloropyridyloxy)] benzene (TCPOBOP) modulates steatohepatitis in the methionine choline-deficient (MCD) diet-fed animal.
METHODS: C57/BL6 wild-type mice were fed the MCD or standard diet for 2 wk and were treated with either the CAR agonist, TCPOBOP, or the CAR inverse agonist, androstanol.
RESULTS: Expression of CYP2B10 and CYP3A11, known CAR target genes, increased 30-fold and 45-fold, respectively, in TCPOBOP-treated mice fed the MCD diet. TCPOBOP treatment reduced hepatic steatosis (44.6 ± 5.4% vs 30.4 ± 4.5%, P < 0.05) and serum triglyceride levels (48 ± 8 vs 20 ± 1 mg/dL, P < 0.05) in MCD diet-fed mice as compared with the standard diet-fed mice. This reduction in hepatic steatosis was accompanied by an increase in enzymes involved in fatty acid microsomal ω-oxidation and peroxisomal β-oxidation, namely CYP4A10, LPBE, and 3-ketoacyl-CoA thiolase. The reduction in steatosis was also accompanied by a reduction in liver cell apoptosis and inflammation. In contrast, androstanol was without effect on any of the above parameters.
CONCLUSION: CAR activation stimulates induction of genes involved in fatty acid oxidation, and ameliorates hepatic steatosis, apoptosis and inflammation.
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