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Gautheron J, Morisseau C, Chung WK, Zammouri J, Auclair M, Baujat G, Capel E, Moulin C, Wang Y, Yang J, Hammock BD, Cerame B, Phan F, Fève B, Vigouroux C, Andreelli F, Jeru I. EPHX1 mutations cause a lipoatrophic diabetes syndrome due to impaired epoxide hydrolysis and increased cellular senescence. eLife 2021; 10:68445. [PMID: 34342583 PMCID: PMC8331186 DOI: 10.7554/elife.68445] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/23/2021] [Indexed: 12/11/2022] Open
Abstract
Epoxide hydrolases (EHs) regulate cellular homeostasis through hydrolysis of epoxides to less-reactive diols. The first discovered EH was EPHX1, also known as mEH. EH functions remain partly unknown, and no pathogenic variants have been reported in humans. We identified two de novo variants located in EPHX1 catalytic site in patients with a lipoatrophic diabetes characterized by loss of adipose tissue, insulin resistance, and multiple organ dysfunction. Functional analyses revealed that these variants led to the protein aggregation within the endoplasmic reticulum and to a loss of its hydrolysis activity. CRISPR-Cas9-mediated EPHX1 knockout (KO) abolished adipocyte differentiation and decreased insulin response. This KO also promoted oxidative stress and cellular senescence, an observation confirmed in patient-derived fibroblasts. Metreleptin therapy had a beneficial effect in one patient. This translational study highlights the importance of epoxide regulation for adipocyte function and provides new insights into the physiological roles of EHs in humans.
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Affiliation(s)
- Jeremie Gautheron
- Sorbonne Université-Inserm UMRS_938, Centre de Recherche Saint-Antoine (CRSA), Paris, France.,Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
| | - Christophe Morisseau
- Department of Entomology and Nematology, and UC Davis Comprehensive Cancer Center, University of California, Davis, Davis, United States
| | - Wendy K Chung
- Department of Pediatrics, Columbia University Irving Medical Center, New York, United States.,Deparment of Medicine, Columbia University Irving Medical Center, New York, United States
| | - Jamila Zammouri
- Sorbonne Université-Inserm UMRS_938, Centre de Recherche Saint-Antoine (CRSA), Paris, France.,Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
| | - Martine Auclair
- Sorbonne Université-Inserm UMRS_938, Centre de Recherche Saint-Antoine (CRSA), Paris, France.,Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
| | - Genevieve Baujat
- Service de Génétique Clinique, Hôpital Necker-Enfants Malades, AP-HP, Paris, France
| | - Emilie Capel
- Sorbonne Université-Inserm UMRS_938, Centre de Recherche Saint-Antoine (CRSA), Paris, France.,Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
| | - Celia Moulin
- Sorbonne Université-Inserm UMRS_938, Centre de Recherche Saint-Antoine (CRSA), Paris, France.,Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
| | - Yuxin Wang
- Department of Entomology and Nematology, and UC Davis Comprehensive Cancer Center, University of California, Davis, Davis, United States
| | - Jun Yang
- Department of Entomology and Nematology, and UC Davis Comprehensive Cancer Center, University of California, Davis, Davis, United States
| | - Bruce D Hammock
- Department of Entomology and Nematology, and UC Davis Comprehensive Cancer Center, University of California, Davis, Davis, United States
| | - Barbara Cerame
- Goryeb Children's Hospital, Atlantic Health Systems, Morristown Memorial Hospital, Morristown, United States
| | - Franck Phan
- Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France.,Service de Diabétologie-Métabolisme, Hôpital Pitié-Salpêtrière, AP-HP, Paris, France.,Sorbonne Université-Inserm UMRS_1269, Paris, France
| | - Bruno Fève
- Sorbonne Université-Inserm UMRS_938, Centre de Recherche Saint-Antoine (CRSA), Paris, France.,Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France.,Centre National de Référence des Pathologies Rares de l'Insulino-Sécrétion et de l'Insulino-Sensibilité (PRISIS), Service de Diabétologie et Endocrinologie de la Reproduction, Hôpital Saint-Antoine, AP-HP, Paris, France
| | - Corinne Vigouroux
- Sorbonne Université-Inserm UMRS_938, Centre de Recherche Saint-Antoine (CRSA), Paris, France.,Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France.,Centre National de Référence des Pathologies Rares de l'Insulino-Sécrétion et de l'Insulino-Sensibilité (PRISIS), Service de Diabétologie et Endocrinologie de la Reproduction, Hôpital Saint-Antoine, AP-HP, Paris, France.,Laboratoire commun de Biologie et Génétique Moléculaires, Hôpital Saint-Antoine, AP-HP, Paris, France
| | - Fabrizio Andreelli
- Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France.,Service de Diabétologie-Métabolisme, Hôpital Pitié-Salpêtrière, AP-HP, Paris, France.,Sorbonne Université-Inserm UMRS_1269, Paris, France
| | - Isabelle Jeru
- Sorbonne Université-Inserm UMRS_938, Centre de Recherche Saint-Antoine (CRSA), Paris, France.,Institute of Cardiometabolism and Nutrition (ICAN), CHU Pitié-Salpêtrière - Saint-Antoine, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France.,Laboratoire commun de Biologie et Génétique Moléculaires, Hôpital Saint-Antoine, AP-HP, Paris, France
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2
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Edin ML, Zeldin DC. Regulation of cardiovascular biology by microsomal epoxide hydrolase. Toxicol Res 2021; 37:285-292. [PMID: 34295793 DOI: 10.1007/s43188-021-00088-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 01/06/2021] [Indexed: 11/29/2022] Open
Abstract
Microsomal epoxide hydrolase/epoxide hydrolase 1 (mEH/EPHX1) works in conjunction with cytochromes P450 to metabolize a variety of compounds, including xenobiotics, pharmaceuticals and endogenous lipids. mEH has been most widely studied for its role in metabolism of xenobiotic and pharmaceutical compounds where it converts hydrophobic and reactive epoxides to hydrophilic diols that are more readily excreted. Inhibition or genetic disruption of mEH can be deleterious in the face of many industrial, environmental or pharmaceutical exposures and EPHX1 polymorphisms are associated with the development of exposure-related cancers. The role of mEH in endogenous epoxy-fatty acid (EpFA) metabolism has been less well studied. In vitro, mEH metabolizes most EpFAs at a far slower rate than soluble epoxide hydrolase (sEH) and has thus been generally considered to exert a minor role in EpFA metabolism in vivo. Indeed, sEH inhibitors or sEH-deficiency increase EpFA levels and are protective in animal models of cardiovascular disease. Recently, however, mEH was found to have a previously unrecognized and substantial role in EpFA metabolism in vivo. While few studies have examined the role of mEH in cardiovascular homeostasis, there is now substantial evidence that mEH can regulate cardiovascular function through regulation of EpFA metabolism. The discovery of a prominent role for mEH in epoxyeicosatrienoic acid (EET) metabolism, in particular, suggests that additional studies on the role of mEH in cardiovascular biology are warranted.
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Affiliation(s)
- Matthew L Edin
- Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, Durham, NC 27709 USA
| | - Darryl C Zeldin
- Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, Durham, NC 27709 USA
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3
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Edin ML, Yamanashi H, Boeglin WE, Graves JP, DeGraff LM, Lih FB, Zeldin DC, Brash AR. Epoxide hydrolase 3 (Ephx3) gene disruption reduces ceramide linoleate epoxide hydrolysis and impairs skin barrier function. J Biol Chem 2021; 296:100198. [PMID: 33334892 PMCID: PMC7948417 DOI: 10.1074/jbc.ra120.016570] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 12/11/2022] Open
Abstract
The mammalian epoxide hydrolase (EPHX)3 is known from in vitro experiments to efficiently hydrolyze the linoleate epoxides 9,10-epoxyoctadecamonoenoic acid (EpOME) and epoxyalcohol 9R,10R-trans-epoxy-11E-13R-hydroxy-octadecenoate to corresponding diols and triols, respectively. Herein we examined the physiological relevance of EPHX3 to hydrolysis of both substrates in vivo. Ephx3−/− mice show no deficiency in EpOME-derived plasma diols, discounting a role for EPHX3 in their formation, whereas epoxyalcohol-derived triols esterified in acylceramides of the epidermal 12R-lipoxygenase pathway are reduced. Although the Ephx3−/− pups appear normal, measurements of transepidermal water loss detected a modest and statistically significant increase compared with the wild-type or heterozygote mice, reflecting a skin barrier impairment that was not evident in the knockouts of mouse microsomal (EPHX1/microsomal epoxide hydrolase) or soluble (EPHX2/sEH). This barrier phenotype in the Ephx3−/− pups was associated with a significant decrease in the covalently bound ceramides in the epidermis (40% reduction, p < 0.05), indicating a corresponding structural impairment in the integrity of the water barrier. Quantitative LC-MS analysis of the esterified linoleate-derived triols in the murine epidermis revealed a marked and isomer-specific reduction (∼85%) in the Ephx3−/− epidermis of the major trihydroxy isomer 9R,10S,13R-trihydroxy-11E-octadecenoate. We conclude that EPHX3 (and not EPHX1 or EPHX2) catalyzes hydrolysis of the 12R-LOX/eLOX3-derived epoxyalcohol esterified in acylceramide and may function to control flux through the alternative and crucial route of metabolism via the dehydrogenation pathway of SDR9C7. Importantly, our findings also identify a functional role for EPHX3 in transformation of a naturally esterified epoxide substrate, pointing to its potential contribution in other tissues.
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Affiliation(s)
- Matthew L Edin
- Division of Intramural Research, NIEHS/NIH, Research Triangle Park, North Carolina, USA
| | - Haruto Yamanashi
- Department of Pharmacology and the Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Department of Dermatology and Allergology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - William E Boeglin
- Department of Pharmacology and the Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Joan P Graves
- Division of Intramural Research, NIEHS/NIH, Research Triangle Park, North Carolina, USA
| | - Laura M DeGraff
- Division of Intramural Research, NIEHS/NIH, Research Triangle Park, North Carolina, USA
| | - Fred B Lih
- Division of Intramural Research, NIEHS/NIH, Research Triangle Park, North Carolina, USA
| | - Darryl C Zeldin
- Division of Intramural Research, NIEHS/NIH, Research Triangle Park, North Carolina, USA.
| | - Alan R Brash
- Department of Pharmacology and the Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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4
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Li Y, Cui J, Jia J. The Activation of Procarcinogens by CYP1A1/1B1 and Related Chemo-Preventive Agents: A Review. Curr Cancer Drug Targets 2021; 21:21-54. [PMID: 33023449 DOI: 10.2174/1568009620666201006143419] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 08/08/2020] [Accepted: 08/20/2020] [Indexed: 02/06/2023]
Abstract
CYP1A1 and CYP1B1 are extrahepatic P450 family members involved in the metabolism of procarcinogens, such as PAHs, heterocyclic amines and halogen-containing organic compounds. CYP1A1/1B1 also participate in the metabolism of endogenous 17-β-estradiol, producing estradiol hydroquinones, which are the intermediates of carcinogenic semiquinones and quinones. CYP1A1 and CYP1B1 proteins share approximately half amino acid sequence identity but differ in crystal structures. As a result, CYP1A1 and CYP1B1 have different substrate specificity to chemical procarcinogens. This review will introduce the general molecular biology knowledge of CYP1A1/1B1 and the metabolic processes of procarcinogens regulated by these two enzymes. Over the last four decades, a variety of natural products and synthetic compounds which interact with CYP1A1/1B1 have been identified as effective chemo-preventive agents against chemical carcinogenesis. These compounds are mainly classified as indirect or direct CYP1A1/1B1 inhibitors based on their distinct mechanisms. Indirect CYP1A1/1B1 inhibitors generally impede the transcription and translation of CYP1A1/1B1 genes or interfere with the translocation of aryl hydrocarbon receptor (AHR) from the cytosolic domain to the nucleus. On the other hand, direct inhibitors inhibit the catalytic activities of CYP1A1/1B1. Based on the structural features, the indirect inhibitors can be categorized into the following groups: flavonoids, alkaloids and synthetic aromatics, whereas the direct inhibitors can be categorized into flavonoids, coumarins, stilbenes, sulfur containing isothiocyanates and synthetic aromatics. This review will summarize the in vitro and in vivo activities of these chemo-preventive agents, their working mechanisms, and related SARs. This will provide a better understanding of the molecular mechanism of CYP1 mediated carcinogenesis and will also give great implications for the discovery of novel chemo-preventive agents in the near future.
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Affiliation(s)
- Yubei Li
- China-UK Low Carbon College, Shanghai Jiaotong University, Shanghai, China
| | - Jiahua Cui
- School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai, China
| | - Jinping Jia
- School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai, China
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5
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The Multifaceted Role of Epoxide Hydrolases in Human Health and Disease. Int J Mol Sci 2020; 22:ijms22010013. [PMID: 33374956 PMCID: PMC7792612 DOI: 10.3390/ijms22010013] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/18/2020] [Accepted: 12/19/2020] [Indexed: 12/12/2022] Open
Abstract
Epoxide hydrolases (EHs) are key enzymes involved in the detoxification of xenobiotics and biotransformation of endogenous epoxides. They catalyze the hydrolysis of highly reactive epoxides to less reactive diols. EHs thereby orchestrate crucial signaling pathways for cell homeostasis. The EH family comprises 5 proteins and 2 candidate members, for which the corresponding genes are not yet identified. Although the first EHs were identified more than 30 years ago, the full spectrum of their substrates and associated biological functions remain partly unknown. The two best-known EHs are EPHX1 and EPHX2. Their wide expression pattern and multiple functions led to the development of specific inhibitors. This review summarizes the most important points regarding the current knowledge on this protein family and highlights the particularities of each EH. These different enzymes can be distinguished by their expression pattern, spectrum of associated substrates, sub-cellular localization, and enzymatic characteristics. We also reevaluated the pathogenicity of previously reported variants in genes that encode EHs and are involved in multiple disorders, in light of large datasets that were made available due to the broad development of next generation sequencing. Although association studies underline the pleiotropic and crucial role of EHs, no data on high-effect variants are confirmed to date.
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6
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Ishitsuka Y, Ogawa T, Roop D. The KEAP1/NRF2 Signaling Pathway in Keratinization. Antioxidants (Basel) 2020; 9:E751. [PMID: 32823937 PMCID: PMC7465315 DOI: 10.3390/antiox9080751] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/09/2020] [Accepted: 08/10/2020] [Indexed: 12/18/2022] Open
Abstract
Keratinization is a tissue adaptation, but aberrant keratinization is associated with skin disorders such as ichthyoses, atopic dermatitis, psoriasis, and acne. The disease phenotype stems from the interaction between genes and the environment; therefore, an understanding of the adaptation machinery may lead to a new appreciation of pathomechanisms. The KEAP1/NRF2 signaling pathway mediates the environmental responses of squamous epithelial tissue. The unpredicted outcome of the Keap1-null mutation in mice allowed us to revisit the basic principle of the biological process of keratinization: sulfur metabolism establishes unparalleled cytoprotection in the body wall of terrestrial mammals. We summarize the recent understanding of the KEAP1/NRF2 signaling pathway, which is a thiol-based sensor-effector apparatus, with particular focuses on epidermal differentiation in the context of the gene-environment interaction, the structure/function principles involved in KEAP1/NRF2 signaling, lessons from mouse models, and their pathological implications. This synthesis may provide insights into keratinization, which provides physical insulation and constitutes an essential innate integumentary defense system.
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Affiliation(s)
- Yosuke Ishitsuka
- Department of Dermatology, Faculty of Medicine, University of Tsukuba 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan;
| | - Tatsuya Ogawa
- Department of Dermatology, Faculty of Medicine, University of Tsukuba 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan;
| | - Dennis Roop
- Department of Dermatology and Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
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7
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Enhanced DNA-repair capacity and resistance to chemically induced carcinogenesis upon deletion of the phosphatase regulator NIPP1. Oncogenesis 2020; 9:30. [PMID: 32123159 PMCID: PMC7051951 DOI: 10.1038/s41389-020-0214-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 11/16/2022] Open
Abstract
Nuclear Inhibitor of PP1 (NIPP1) is a conserved regulatory subunit of protein phosphatase PP1. The selective deletion of NIPP1 in mouse liver parenchymal cells or skin epidermal cells culminates in a late-onset hyperproliferation of a subset of resident progenitor cells. Although a hyperplastic phenotype is usually tumor promoting, we show here that the absence of NIPP1 conferred a strong resistance to chemically induced hepatocellular or skin carcinoma. The ablation of NIPP1 did not affect the metabolism of the administered mutagens (diethylnitrosamine or 7,12-dimethylbenz[a]anthracene), but reduced the conversion of mutagen-induced covalent DNA modifications into cancer-initiating mutations. This reduced sensitivity to mutagens correlated with an enhanced DNA-damage response and an augmented expression of rate-limiting DNA-repair proteins (MGMT in liver, XPD and XPG in skin), hinting at an increased DNA-repair capacity. Our data identify NIPP1 as a repressor of DNA repair and as a promising target for novel cancer prevention and treatment therapies.
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8
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Protein kinase Cδ mediates methamphetamine-induced dopaminergic neurotoxicity in mice via activation of microsomal epoxide hydrolase. Food Chem Toxicol 2019; 133:110761. [PMID: 31422080 DOI: 10.1016/j.fct.2019.110761] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 08/09/2019] [Accepted: 08/13/2019] [Indexed: 12/17/2022]
Abstract
We previously demonstrated that activation of protein kinase Cδ (PKCδ) is critical for methamphetamine (MA)-induced dopaminergic toxicity. It was recognized that microsomal epoxide hydrolase (mEH) also induces dopaminergic neurotoxicity. It was demonstrated that inhibition of PKC modulates the expression of mEH. We investigated whether MA-induced PKCδ activation requires mEH induction in mice. MA treatment (8 mg/kg, i.p., × 4; 2 h interval) significantly enhanced the level of phosphorylated PKCδ in the striatum of wild type (WT) mice. Subsequently, treatment with MA resulted in significant increases in the expression of cleaved PKCδ and mEH. Treatment with MA resulted in enhanced interaction between PKCδ and mEH. PKCδ knockout mice exhibited significant attenuation of the enhanced mEH expression induced by MA. MA-induced hyperthermia, oxidative stress, proapoptotic potentials, and dopaminergic impairments were attenuated by PKCδ knockout or mEH knockout in mice. However, treating mEH knockout in mice with PKCδ inhibitor, rottlerin did not show any additive beneficial effects, indicating that mEH is a critical mediator of neurotoxic potential of PKCδ. Our results suggest that MA-induced PKCδ activation requires mEH induction as a downstream signaling pathway and that the modulation of the PKCδ and mEH interaction is important for the pharmacological intervention against MA-induced dopaminergic neurotoxicity.
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9
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Primary aromatic amines and cancer: Novel mechanistic insights using 4-aminobiphenyl as a model carcinogen. Pharmacol Ther 2019; 200:179-189. [DOI: 10.1016/j.pharmthera.2019.05.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 05/02/2019] [Indexed: 02/07/2023]
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10
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van de Graaf SFJ, Slijepcevic D. Reply. Hepatology 2018; 67:1185-1186. [PMID: 29211937 DOI: 10.1002/hep.29709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 12/02/2017] [Indexed: 12/07/2022]
Affiliation(s)
- S F J van de Graaf
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, the Netherlands
| | - Davor Slijepcevic
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, the Netherlands
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11
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Tsukayama I, Toda K, Takeda Y, Mega T, Tanaka M, Kawakami Y, Takahashi Y, Kimoto M, Yamamoto K, Miki Y, Murakami M, Suzuki-Yamamoto T. Preventive effect of Dioscorea japonica on squamous cell carcinoma of mouse skin involving down-regulation of prostaglandin E 2 synthetic pathway. J Clin Biochem Nutr 2018; 62:139-147. [PMID: 29610553 PMCID: PMC5874233 DOI: 10.3164/jcbn.17-54] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 09/08/2017] [Indexed: 01/12/2023] Open
Abstract
Hyperproduced prostaglandin E2 by cyclooxygenase-2 and microsomal prostaglandin E synthase-1 evokes several pathophysiological responses such as inflammation and carcinogenesis. Our recent study demonstrated that Dioscorea japonica extract suppressed the expression of cyclooxygenase-2 and microsomal prostaglandin E synthase-1 and induced apoptosis in lung carcinoma A549 cells. In the present study, we investigated the effects of Dioscorea japonica on squamous cell carcinoma of mouse skin. Dioscorea japonica feeding and Dioscorea japonica extract topical application suppressed the expression of cyclooxygenase-2, microsomal prostaglandin E synthase-1, interleukin-1β and interleukin-6 and inhibited tumor formation, hyperplasia and inflammatory cell infiltration. Immunohistochemical analyses showed the immunoreactivities of cyclooxygenase-2 and microsomal prostaglandin E synthase-1 in tumor keratinocytes and stronger immunoreactivities of cyclooxygenase-2 and hematopoietic prostaglandin D synthase in epidermal dendritic cells (Langerhans cells). Treatment with Dioscorea japonica decreased the immunoreactivity of cyclooxygenase-2 and microsomal prostaglandin E synthase-1. These results indicate that Dioscorea japonica may have inhibitory effects on inflammation and carcinogenesis via suppression of the prostaglandin E2 synthetic pathway.
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Affiliation(s)
- Izumi Tsukayama
- Department of Nutritional Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197, Japan
| | - Keisuke Toda
- Department of Nutritional Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197, Japan
| | - Yasunori Takeda
- Department of Nutritional Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197, Japan
| | - Takuto Mega
- Department of Nutritional Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197, Japan
| | - Mitsuki Tanaka
- Department of Nutritional Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197, Japan
| | - Yuki Kawakami
- Department of Nutritional Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197, Japan
| | - Yoshitaka Takahashi
- Department of Nutritional Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197, Japan
| | - Masumi Kimoto
- Department of Nutritional Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197, Japan
| | - Kei Yamamoto
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan.,Graduate School of Technology, Industrial and Social Science, Tokushima University, Minami-jyosanjima, Tokushima 770-8513, Japan.,PRIME, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo 100-0004, Japan
| | - Yoshimi Miki
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan.,Laboratory of Microenvironmental and Metabolic Health Sciences, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Makoto Murakami
- Lipid Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan.,Laboratory of Microenvironmental and Metabolic Health Sciences, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.,AMED-CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo 100-0004, Japan
| | - Toshiko Suzuki-Yamamoto
- Department of Nutritional Science, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197, Japan
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12
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Edin ML, Hamedani BG, Gruzdev A, Graves JP, Lih FB, Arbes SJ, Singh R, Orjuela Leon AC, Bradbury JA, DeGraff LM, Hoopes SL, Arand M, Zeldin DC. Epoxide hydrolase 1 (EPHX1) hydrolyzes epoxyeicosanoids and impairs cardiac recovery after ischemia. J Biol Chem 2018; 293:3281-3292. [PMID: 29298899 DOI: 10.1074/jbc.ra117.000298] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/15/2017] [Indexed: 12/12/2022] Open
Abstract
Stimuli such as inflammation or hypoxia induce cytochrome P450 epoxygenase-mediated production of arachidonic acid-derived epoxyeicosatrienoic acids (EETs). EETs have cardioprotective, vasodilatory, angiogenic, anti-inflammatory, and analgesic effects, which are diminished by EET hydrolysis yielding biologically less active dihydroxyeicosatrienoic acids (DHETs). Previous in vitro assays have suggested that epoxide hydrolase 2 (EPHX2) is responsible for nearly all EET hydrolysis. EPHX1, which exhibits slow EET hydrolysis in vitro, is thought to contribute only marginally to EET hydrolysis. Using Ephx1-/-, Ephx2-/-, and Ephx1-/-Ephx2-/- mice, we show here that EPHX1 significantly contributes to EET hydrolysis in vivo Disruption of Ephx1 and/or Ephx2 genes did not induce compensatory changes in expression of other Ephx genes or CYP2 family epoxygenases. Plasma levels of 8,9-, 11,12-, and 14,15-DHET were reduced by 38, 44, and 67% in Ephx2-/- mice compared with wildtype (WT) mice, respectively; however, plasma from Ephx1-/-Ephx2-/- mice exhibited significantly greater reduction (100, 99, and 96%) of those respective DHETs. Kinetic assays and FRET experiments indicated that EPHX1 is a slow EET scavenger, but hydrolyzes EETs in a coupled reaction with cytochrome P450 to limit basal EET levels. Moreover, we also found that EPHX1 activities are biologically relevant, as Ephx1-/-Ephx2-/- hearts had significantly better postischemic functional recovery (71%) than both WT (31%) and Ephx2-/- (51%) hearts. These findings indicate that Ephx1-/-Ephx2-/- mice are a valuable model for assessing EET-mediated effects, uncover a new paradigm for EET metabolism, and suggest that dual EPHX1 and EPHX2 inhibition may represent a therapeutic approach to manage human pathologies such as myocardial infarction.
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Affiliation(s)
- Matthew L Edin
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
| | - Behin Gholipour Hamedani
- the Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Artiom Gruzdev
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
| | - Joan P Graves
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
| | - Fred B Lih
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
| | - Samuel J Arbes
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
| | - Rohanit Singh
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
| | - Anette C Orjuela Leon
- the Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - J Alyce Bradbury
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
| | - Laura M DeGraff
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
| | - Samantha L Hoopes
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
| | - Michael Arand
- the Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Darryl C Zeldin
- From the Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709 and
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Beyond detoxification: a role for mouse mEH in the hepatic metabolism of endogenous lipids. Arch Toxicol 2017; 91:3571-3585. [PMID: 28975360 PMCID: PMC5696502 DOI: 10.1007/s00204-017-2060-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 09/04/2017] [Indexed: 12/24/2022]
Abstract
Microsomal and soluble epoxide hydrolase (mEH and sEH) fulfill apparently distinct roles: Whereas mEH detoxifies xenobiotics, sEH hydrolyzes fatty acid (FA) signaling molecules and is thus implicated in a variety of physiological functions. These epoxy FAs comprise epoxyeicosatrienoic acids (EETs) and epoxy-octadecenoic acids (EpOMEs), which are formed by CYP epoxygenases from arachidonic acid (AA) and linoleic acid, respectively, and then are hydrolyzed to their respective diols, the so-called DHETs and DiHOMEs. Although EETs and EpOMEs are also substrates for mEH, its role in lipid signaling is considered minor due to lower abundance and activity relative to sEH. Surprisingly, we found that in plasma from mEH KO mice, hydrolysis rates for 8,9-EET and 9,10-EpOME were reduced by 50% compared to WT plasma. This strongly suggests that mEH contributes substantially to the turnover of these FA epoxides—despite kinetic parameters being in favor of sEH. Given the crucial role of liver in controlling plasma diol levels, we next studied the capacity of sEH and mEH KO liver microsomes to synthesize DHETs with varying concentrations of AA (1–30 μM) and NADPH. mEH-generated DHET levels were similar to the ones generated by sEH, when AA concentrations were low (1 μM) or epoxygenase activity was curbed by modulating NADPH. With increasing AA concentrations sEH became more dominant and with 30 μM AA produced twice the level of DHETs compared to mEH. Immunohistochemistry of C57BL/6 liver slices further revealed that mEH expression was more widespread than sEH expression. mEH immunoreactivity was detected in hepatocytes, Kupffer cells, endothelial cells, and bile duct epithelial cells, while sEH immunoreactivity was confined to hepatocytes and bile duct epithelial cells. Finally, transcriptome analysis of WT, mEH KO, and sEH KO liver was carried out to discern transcriptional changes associated with the loss of EH genes along the CYP-epoxygenase–EH axis. We found several prominent dysregulations occurring in a parallel manner in both KO livers: (a) gene expression of Ephx1 (encoding for mEH protein) was increased 1.35-fold in sEH KO, while expression of Ephx2 (encoding for sEH protein) was increased 1.4-fold in mEH KO liver; (b) Cyp2c genes, encoding for the predominant epoxygenases in mouse liver, were mostly dysregulated in the same manner in both sEH and mEH KO mice, showing that loss of either EH has a similar impact. Taken together, mEH appears to play a leading role in the hydrolysis of 8,9-EET and 9,10-EpOME and also contributes to the hydrolysis of other FA epoxides. It probably profits from its high affinity for FA epoxides under non-saturating conditions and its close physical proximity to CYP epoxygenases, and compensates its lower abundance by a more widespread expression, being the only EH present in several sEH-lacking cell types.
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14
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Goswami SK, Rand AA, Wan D, Yang J, Inceoglu B, Thomas M, Morisseau C, Yang GY, Hammock BD. Pharmacological inhibition of soluble epoxide hydrolase or genetic deletion reduces diclofenac-induced gastric ulcers. Life Sci 2017; 180:114-122. [PMID: 28522175 DOI: 10.1016/j.lfs.2017.05.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 05/08/2017] [Accepted: 05/14/2017] [Indexed: 12/13/2022]
Abstract
AIMS This research was conducted to evaluate the hypothesis that gastric ulcers caused by the NSAID diclofenac sodium (DCF) can be prevented by the soluble epoxide hydrolase inhibitor TPPU. MAIN METHODS Mice were administered a single dose of 10, 30 or 100mg/kg of DCF. Once an ulcerative dose of DCF was chosen, mice were pretreated with TPPU for 7days at 0.1mg/kg to evaluate anti-ulcer effects of the sEH inhibitor on anatomy, histopathology, pH, inflammatory markers and epithelial apoptosis of stomachs. KEY FINDINGS Diclofenac caused ulceration of the stomach at a dose of 100mg/kg and a time post dose of 6h. Ulcers generated under these conditions were associated with a significant increase in the levels of TNF-α and IL-6 in serum and increased apoptosis compared to control mice. Pretreatment with TPPU resulted in a decrease of ulceration in mice treated with DCF with a significant decrease in the level of apoptosis, TNF-α and IL-6 in the serum in comparison to diclofenac-treated mice. TPPU did not affect the pH of the stomach, whereas omeprazole elevated the pH of the stomach as expected. A similar anti-ulcer effect was observed in sEH gene knockout mice treated with DCF. SIGNIFICANCE The sEH inhibitor TPPU decreases the NSAID-induced stomach ulcers.
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Affiliation(s)
- Sumanta Kumar Goswami
- Department of Entomology and Nematology, and Comprehensive Cancer Center, University of California, Davis, CA 95616, USA
| | - Amelia Ann Rand
- Department of Entomology and Nematology, and Comprehensive Cancer Center, University of California, Davis, CA 95616, USA
| | - Debin Wan
- Department of Entomology and Nematology, and Comprehensive Cancer Center, University of California, Davis, CA 95616, USA
| | - Jun Yang
- Department of Entomology and Nematology, and Comprehensive Cancer Center, University of California, Davis, CA 95616, USA
| | - Bora Inceoglu
- Department of Entomology and Nematology, and Comprehensive Cancer Center, University of California, Davis, CA 95616, USA
| | - Melany Thomas
- Department of Entomology and Nematology, and Comprehensive Cancer Center, University of California, Davis, CA 95616, USA
| | - Christophe Morisseau
- Department of Entomology and Nematology, and Comprehensive Cancer Center, University of California, Davis, CA 95616, USA
| | - Guang-Yu Yang
- Department of Pathology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
| | - Bruce D Hammock
- Department of Entomology and Nematology, and Comprehensive Cancer Center, University of California, Davis, CA 95616, USA.
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15
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Shimada T. Inhibition of Carcinogen-Activating Cytochrome P450 Enzymes by Xenobiotic Chemicals in Relation to Antimutagenicity and Anticarcinogenicity. Toxicol Res 2017; 33:79-96. [PMID: 28443179 PMCID: PMC5402866 DOI: 10.5487/tr.2017.33.2.079] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 02/16/2017] [Indexed: 12/27/2022] Open
Abstract
A variety of xenobiotic chemicals, such as polycyclic aromatic hydrocarbons (PAHs), aryl- and heterocyclic amines and tobacco related nitrosamines, are ubiquitous environmental carcinogens and are required to be activated to chemically reactive metabolites by xenobiotic-metabolizing enzymes, including cytochrome P450 (P450 or CYP), in order to initiate cell transformation. Of various human P450 enzymes determined to date, CYP1A1, 1A2, 1B1, 2A13, 2A6, 2E1, and 3A4 are reported to play critical roles in the bioactivation of these carcinogenic chemicals. In vivo studies have shown that disruption of Cyp1b1 and Cyp2a5 genes in mice resulted in suppression of tumor formation caused by 7,12-dimethylbenz[a]anthracene and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, respectively. In addition, specific inhibitors for CYP1 and 2A enzymes are able to suppress tumor formation caused by several carcinogens in experimental animals in vivo, when these inhibitors are applied before or just after the administration of carcinogens. In this review, we describe recent progress, including our own studies done during past decade, on the nature of inhibitors of human CYP1 and CYP2A enzymes that have been shown to activate carcinogenic PAHs and tobacco-related nitrosamines, respectively, in humans. The inhibitors considered here include a variety of carcinogenic and/or non-carcinogenic PAHs and acethylenic PAHs, many flavonoid derivatives, derivatives of naphthalene, phenanthrene, biphenyl, and pyrene and chemopreventive organoselenium compounds, such as benzyl selenocyanate and benzyl selenocyanate; o-XSC, 1,2-, 1,3-, and 1,4-phenylenebis( methylene)selenocyanate.
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Affiliation(s)
- Tsutomu Shimada
- Laboratory of Cellular and Molecular Biology, Graduate School of Life and Environmental Sciences, Veterinary Sciences, Osaka Prefecture University, Osaka, Japan
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16
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The cold-induced lipokine 12,13-diHOME promotes fatty acid transport into brown adipose tissue. Nat Med 2017; 23:631-637. [PMID: 28346411 DOI: 10.1038/nm.4297] [Citation(s) in RCA: 282] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/03/2017] [Indexed: 12/15/2022]
Abstract
Brown adipose tissue (BAT) and beige adipose tissue combust fuels for heat production in adult humans, and so constitute an appealing target for the treatment of metabolic disorders such as obesity, diabetes and hyperlipidemia. Cold exposure can enhance energy expenditure by activating BAT, and it has been shown to improve nutrient metabolism. These therapies, however, are time consuming and uncomfortable, demonstrating the need for pharmacological interventions. Recently, lipids have been identified that are released from tissues and act locally or systemically to promote insulin sensitivity and glucose tolerance; as a class, these lipids are referred to as 'lipokines'. Because BAT is a specialized metabolic tissue that takes up and burns lipids and is linked to systemic metabolic homeostasis, we hypothesized that there might be thermogenic lipokines that activate BAT in response to cold. Here we show that the lipid 12,13-dihydroxy-9Z-octadecenoic acid (12,13-diHOME) is a stimulator of BAT activity, and that its levels are negatively correlated with body-mass index and insulin sensitivity. Using a global lipidomic analysis, we found that 12,13-diHOME was increased in the circulation of humans and mice exposed to cold. Furthermore, we found that the enzymes that produce 12,13-diHOME were uniquely induced in BAT by cold stimulation. The injection of 12,13-diHOME acutely activated BAT fuel uptake and enhanced cold tolerance, which resulted in decreased levels of serum triglycerides. Mechanistically, 12,13-diHOME increased fatty acid (FA) uptake into brown adipocytes by promoting the translocation of the FA transporters FATP1 and CD36 to the cell membrane. These data suggest that 12,13-diHOME, or a functional analog, could be developed as a treatment for metabolic disorders.
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17
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Effect of layer thickness on the elution of bulk-fill composite components. Dent Mater 2017; 33:54-62. [DOI: 10.1016/j.dental.2016.10.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 09/30/2016] [Accepted: 10/24/2016] [Indexed: 12/21/2022]
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18
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Toivonen S, Romppanen EL, Hiltunen M, Helisalmi S, Keski-Nisula L, Punnonen K, Heinonen S. Low-Activity Haplotype of the Microsomal Epoxide Hydrolase Gene Is Protective Against Placental Abruption. ACTA ACUST UNITED AC 2016; 11:540-4. [PMID: 15582499 DOI: 10.1016/j.jsgi.2004.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE We wanted to determine whether genetic variability in the gene encoding microsomal epoxide hydrolase (EPHX) contributes to individual differences in susceptibility to the occurrence of placental abruption. METHODS The study involved 117 women with placental abruption and 115 healthy control pregnant women who were genotyped for two single nucleotide polymorphisms (SNPs), T-->C (Tyr113His) in exon 3 and A-->G (His139Arg) in exon 4, in the EPHX gene. Chi-square analysis was used to assess genotype and allele frequency differences between the women with placental abruption and the control group. In addition, single-point analysis was expanded to pair of loci haplotype analysis to examine the estimated haplotype frequencies of the two SNPs, of unknown phase, among the women with placental abruption and the control group. Estimated haplotype frequencies were assessed using the maximum-likelihood method, employing an expectation-maximization algorithm. RESULTS Single-point allele and genotype distributions in exons 3 and 4 of the EPHX gene were not statistically different between the groups. However, in the haplotype estimation analysis we observed a significantly decreased frequency of haplotype C-A (His113-His139) among the placental abruption group compared with the control group (P = .007). The odds ratio for placental abruption associated with the low-activity haplotype C-A (His113-His139) was 0.552 (95% confidence interval, 0.358 to 0.851). CONCLUSIONS The use of two intragenic SNPs jointly in haplotype analysis of association demonstrated that the genetically determined low-activity haplotype C-A (His113-His139) was significantly less frequent in women with placental abruption.
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Affiliation(s)
- Sari Toivonen
- Department of Obstetrics and Gynaecology, Kuopio University and University Hospital, Kuopio, Finland
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19
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Ganesan S, Keating AF. Bisphenol A-Induced Ovotoxicity Involves DNA Damage Induction to Which the Ovary Mounts a Protective Response Indicated by Increased Expression of Proteins Involved in DNA Repair and Xenobiotic Biotransformation. Toxicol Sci 2016; 152:169-80. [DOI: 10.1093/toxsci/kfw076] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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20
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Chiba T, Thomas CP, Calcutt MW, Boeglin WE, O'Donnell VB, Brash AR. The Precise Structures and Stereochemistry of Trihydroxy-linoleates Esterified in Human and Porcine Epidermis and Their Significance in Skin Barrier Function: IMPLICATION OF AN EPOXIDE HYDROLASE IN THE TRANSFORMATIONS OF LINOLEATE. J Biol Chem 2016; 291:14540-54. [PMID: 27151221 PMCID: PMC4938176 DOI: 10.1074/jbc.m115.711267] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Indexed: 12/02/2022] Open
Abstract
Creation of an intact skin water barrier, a prerequisite for life on dry land,
requires the lipoxygenase-catalyzed oxidation of the essential fatty acid linoleate,
which is esterified to the ω-hydroxyl of an epidermis-specific ceramide.
Oxidation of the linoleate moiety by lipoxygenases is proposed to facilitate
enzymatic cleavage of the ester bond, releasing free ω-hydroxyceramide for
covalent binding to protein, thus forming the corneocyte lipid envelope, a key
component of the epidermal barrier. Herein, we report the transformations of
esterified linoleate proceed beyond the initial steps of oxidation and epoxyalcohol
synthesis catalyzed by the consecutive actions of 12R-LOX and
epidermal LOX3. The major end product in human and porcine epidermis is a trihydroxy
derivative, formed with a specificity that implicates participation of an epoxide
hydrolase in converting epoxyalcohol to triol. Of the 16 possible triols arising from
hydrolysis of 9,10-epoxy-13-hydroxy-octadecenoates, using LC-MS and chiral analyses,
we identify and quantify specifically
9R,10S,13R-trihydroxy-11E-octadecenoate
as the single major triol esterified in porcine epidermis and the same isomer with
lesser amounts of its 10R diastereomer in human epidermis. The
9R,10S,13R-triol is formed by
SN2 hydrolysis of the
9R,10R-epoxy-13R-hydroxy-octadecenoate
product of the LOX enzymes, a reaction specificity characteristic of epoxide
hydrolase. The high polarity of triol over the primary linoleate products enhances
the concept that the oxidations disrupt corneocyte membrane lipids, promoting release
of free ω-hydroxyceramide for covalent binding to protein and sealing of the
waterproof barrier.
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Affiliation(s)
| | - Christopher P Thomas
- the Systems Immunity Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XN, Wales, United Kingdom
| | - M Wade Calcutt
- Biochemistry and the Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232 and
| | | | - Valerie B O'Donnell
- the Systems Immunity Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XN, Wales, United Kingdom
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Goswami SK, Wan D, Yang J, Trindade da Silva CA, Morisseau C, Kodani SD, Yang GY, Inceoglu B, Hammock BD. Anti-Ulcer Efficacy of Soluble Epoxide Hydrolase Inhibitor TPPU on Diclofenac-Induced Intestinal Ulcers. J Pharmacol Exp Ther 2016; 357:529-36. [PMID: 26989141 DOI: 10.1124/jpet.116.232108] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 03/16/2016] [Indexed: 12/18/2022] Open
Abstract
Proton pump inhibitors such as omeprazole (OME) reduce the severity of gastrointestinal (GI) ulcers induced by nonsteroidal anti-inflammatory drugs (NSAIDs) but can also increase the chance of dysbiosis. The aim of this study was to test the hypothesis that preventive use of a soluble epoxide hydrolase inhibitor (sEHI) such as TPPU can decrease NSAID-induced ulcers by increasing anti-inflammatory epoxyeicosatrienoic acids (EETs). Dose- [10, 30, and 100 mg/kg, by mouth (PO)] and time-dependent (6 and 18 hours) ulcerative effects of diclofenac sodium (DCF, an NSAID) were studied in the small intestine of Swiss Webster mice. Dose-dependent effects of TPPU (0.001-0.1 mg/kg per day for 7 days, in drinking water) were evaluated in DCF-induced intestinal toxicity and compared with OME (20 mg/kg, PO). In addition, the effect of treatment was studied on levels of Hb in blood, EETs in plasma, inflammatory markers such as myeloperoxidase (MPO) in intestinal tissue homogenates, and tissue necrosis factor-α (TNF-α) in serum. DCF dose dependently induced ulcers that were associated with both a significant (P < 0.05) loss of Hb and an increase in the level of MPO and TNF-α, with severity of ulceration highest at 18 hours. Pretreatment with TPPU dose dependently prevented ulcer formation by DCF, increased the levels of epoxy fatty acids, including EETs, and TPPU's efficacy was comparable to OME. TPPU significantly (P < 0.05) reversed the effect of DCF on the level of Hb, MPO, and TNF-α Thus sEHI might be useful in the management of NSAID-induced ulcers.
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Affiliation(s)
- Sumanta Kumar Goswami
- Department of Entomology and Nematology, and Comprehensive Cancer Center (S.K.G., D.W., J.Y., C.A.T.S., C.M., S.D.K., B.I., B.D.H.), University of California-Davis, Davis, California; Department of Genetics and Biochemistry (C.A.T.S.), Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil; Department of Pathology (G.-Y.Y.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Debin Wan
- Department of Entomology and Nematology, and Comprehensive Cancer Center (S.K.G., D.W., J.Y., C.A.T.S., C.M., S.D.K., B.I., B.D.H.), University of California-Davis, Davis, California; Department of Genetics and Biochemistry (C.A.T.S.), Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil; Department of Pathology (G.-Y.Y.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Jun Yang
- Department of Entomology and Nematology, and Comprehensive Cancer Center (S.K.G., D.W., J.Y., C.A.T.S., C.M., S.D.K., B.I., B.D.H.), University of California-Davis, Davis, California; Department of Genetics and Biochemistry (C.A.T.S.), Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil; Department of Pathology (G.-Y.Y.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Carlos A Trindade da Silva
- Department of Entomology and Nematology, and Comprehensive Cancer Center (S.K.G., D.W., J.Y., C.A.T.S., C.M., S.D.K., B.I., B.D.H.), University of California-Davis, Davis, California; Department of Genetics and Biochemistry (C.A.T.S.), Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil; Department of Pathology (G.-Y.Y.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Christophe Morisseau
- Department of Entomology and Nematology, and Comprehensive Cancer Center (S.K.G., D.W., J.Y., C.A.T.S., C.M., S.D.K., B.I., B.D.H.), University of California-Davis, Davis, California; Department of Genetics and Biochemistry (C.A.T.S.), Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil; Department of Pathology (G.-Y.Y.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Sean D Kodani
- Department of Entomology and Nematology, and Comprehensive Cancer Center (S.K.G., D.W., J.Y., C.A.T.S., C.M., S.D.K., B.I., B.D.H.), University of California-Davis, Davis, California; Department of Genetics and Biochemistry (C.A.T.S.), Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil; Department of Pathology (G.-Y.Y.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Guang-Yu Yang
- Department of Entomology and Nematology, and Comprehensive Cancer Center (S.K.G., D.W., J.Y., C.A.T.S., C.M., S.D.K., B.I., B.D.H.), University of California-Davis, Davis, California; Department of Genetics and Biochemistry (C.A.T.S.), Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil; Department of Pathology (G.-Y.Y.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Bora Inceoglu
- Department of Entomology and Nematology, and Comprehensive Cancer Center (S.K.G., D.W., J.Y., C.A.T.S., C.M., S.D.K., B.I., B.D.H.), University of California-Davis, Davis, California; Department of Genetics and Biochemistry (C.A.T.S.), Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil; Department of Pathology (G.-Y.Y.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Bruce D Hammock
- Department of Entomology and Nematology, and Comprehensive Cancer Center (S.K.G., D.W., J.Y., C.A.T.S., C.M., S.D.K., B.I., B.D.H.), University of California-Davis, Davis, California; Department of Genetics and Biochemistry (C.A.T.S.), Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil; Department of Pathology (G.-Y.Y.), Feinberg School of Medicine, Northwestern University, Chicago, Illinois
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Marowsky A, Haenel K, Bockamp E, Heck R, Rutishauser S, Mule N, Kindler D, Rudin M, Arand M. Genetic enhancement of microsomal epoxide hydrolase improves metabolic detoxification but impairs cerebral blood flow regulation. Arch Toxicol 2016; 90:3017-3027. [PMID: 26838043 PMCID: PMC5104800 DOI: 10.1007/s00204-016-1666-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 01/06/2016] [Indexed: 01/05/2023]
Abstract
Microsomal epoxide hydrolase (mEH) is a detoxifying enzyme for xenobiotic compounds. Enzymatic activity of mEH can be greatly increased by a point mutation, leading to an E404D amino acid exchange in its catalytic triad. Surprisingly, this variant is not found in any vertebrate species, despite the obvious advantage of accelerated detoxification. We hypothesized that this evolutionary avoidance is due to the fact that the mEH plays a dualistic role in detoxification and control of endogenous vascular signaling molecules. To test this, we generated mEH E404D mice and assessed them for detoxification capacity and vascular dynamics. In liver microsomes from these mice, turnover of the xenobiotic compound phenanthrene-9,10-oxide was four times faster compared to WT liver microsomes, confirming accelerated detoxification. mEH E404D animals also showed faster metabolization of a specific class of endogenous eicosanoids, arachidonic acid-derived epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs). Significantly higher DHETs/EETs ratios were found in mEH E404D liver, urine, plasma, brain and cerebral endothelial cells compared to WT controls, suggesting a broad impact of the mEH mutant on endogenous EETs metabolism. Because EETs are strong vasodilators in cerebral vasculature, hemodynamics were assessed in mEH E404D and WT cerebral cortex and hippocampus using cerebral blood volume (CBV)-based functional magnetic resonance imaging (fMRI). Basal CBV0 levels were similar between mEH E404D and control mice in both brain areas. But vascular reactivity and vasodilation in response to the vasodilatory drug acetazolamide were reduced in mEH E404D forebrain compared to WT controls by factor 3 and 2.6, respectively. These results demonstrate a critical role for mEH E404D in vasodynamics and suggest that deregulation of endogenous signaling pathways is the undesirable gain of function associated with the E404D variant.
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Affiliation(s)
- Anne Marowsky
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Karen Haenel
- Institute of Complex Systems (ICS-6), Research Center Julich, Wilhelm-Johnen-Straße, 52425, Julich, Germany
| | - Ernesto Bockamp
- Institute of Translational Immunology, University of Mainz, Obere Zahlbacherstrasse 63, 55131, Mainz, Germany
| | - Rosario Heck
- Institute of Translational Immunology, University of Mainz, Obere Zahlbacherstrasse 63, 55131, Mainz, Germany
| | - Sibylle Rutishauser
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Nandkishor Mule
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Diana Kindler
- Institute for Biomedical Engineering, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093, Zurich, Switzerland
| | - Markus Rudin
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Institute for Biomedical Engineering, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093, Zurich, Switzerland
| | - Michael Arand
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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Tie JK, Stafford DW. Structural and functional insights into enzymes of the vitamin K cycle. J Thromb Haemost 2016; 14:236-47. [PMID: 26663892 PMCID: PMC5073812 DOI: 10.1111/jth.13217] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/25/2015] [Indexed: 12/20/2022]
Abstract
Vitamin K-dependent proteins require carboxylation of certain glutamates for their biological functions. The enzymes involved in the vitamin K-dependent carboxylation include: gamma-glutamyl carboxylase (GGCX), vitamin K epoxide reductase (VKOR) and an as-yet-unidentified vitamin K reductase (VKR). Due to the hydrophobicity of vitamin K, these enzymes are likely to be integral membrane proteins that reside in the endoplasmic reticulum. Therefore, structure-function studies on these enzymes have been challenging, and some of the results are notably controversial. Patients with naturally occurring mutations in these enzymes, who mainly exhibit bleeding disorders or are resistant to oral anticoagulant treatment, provide valuable information for the functional study of the vitamin K cycle enzymes. In this review, we discuss: (i) the discovery of the enzymatic activities and gene identifications of the vitamin K cycle enzymes; (ii) the identification of their functionally important regions and their active site residues; (iii) the membrane topology studies of GGCX and VKOR; and (iv) the controversial issues regarding the structure and function studies of these enzymes, particularly, the membrane topology, the role of the conserved cysteines and the mechanism of active site regeneration of VKOR. We also discuss the possibility that a paralogous protein of VKOR, VKOR-like 1 (VKORL1), is involved in the vitamin K cycle, and the importance of and possible approaches for identifying the unknown VKR. Overall, we describe the accomplishments and the remaining questions in regard to the structure and function studies of the enzymes in the vitamin K cycle.
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Affiliation(s)
- J-K Tie
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - D W Stafford
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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Carratt SA, Morin D, Buckpitt AR, Edwards PC, Van Winkle LS. Naphthalene cytotoxicity in microsomal epoxide hydrolase deficient mice. Toxicol Lett 2016; 246:35-41. [PMID: 26840748 DOI: 10.1016/j.toxlet.2016.01.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 01/16/2016] [Accepted: 01/24/2016] [Indexed: 12/01/2022]
Abstract
Naphthalene (NA) is a ubiquitous pollutant to which humans are widely exposed. 1,2-Dihydro-1,2-dihydroxynaphthalene (NA-dihydrodiol) is a major metabolite of NA generated by microsomal epoxide hydrolase (mEH). To investigate the role of the NA-dihydrodiol and subsequent metabolites (i.e. 1,2-naphthoquinone) in cytotoxicity, we exposed both male and female wild type (WT) and mEH null mice (KO) to NA by inhalation (5, 10, 20 ppm for 4h). NA-dihydrodiol was ablated in the KO mice. High-resolution histopathology was used to study site-specific cytotoxicity, and formation of naphthalene metabolites was measured by HPLC in microdissected airways. Swollen and vacuolated airway epithelial cells were observed in the intra- and extrapulmonary airways of all mice at and below the current OSHA standard (10 ppm). Female mice may be more susceptible to this acute cytotoxicity. In the extrapulmonary airways, WT mice were more susceptible to damage than KO mice, indicating that the metabolites associated with mEH-mediated metabolism could be partially responsible for cytotoxicity at this site. The level of cytotoxicity in the mEH KO mice at all airway levels suggests that non-mEH metabolites are contributing to NA cellular damage in the lung. Our results indicate that the apparent contribution of mEH-dependent metabolites to toxicity differs by location in the lung. These studies suggest that metabolites generated through the mEH pathway may be of minor importance in distal airway toxicity and subsequent carcinogenesis from NA exposure.
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Affiliation(s)
- S A Carratt
- Center for Health and the Environment, University of California Davis, Davis, CA 95616, USA
| | - D Morin
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA
| | - A R Buckpitt
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA
| | - P C Edwards
- Center for Health and the Environment, University of California Davis, Davis, CA 95616, USA
| | - L S Van Winkle
- Center for Health and the Environment, University of California Davis, Davis, CA 95616, USA; Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA.
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Lim J, Ortiz L, Nakamura BN, Hoang YD, Banuelos J, Flores VN, Chan JY, Luderer U. Effects of deletion of the transcription factor Nrf2 and benzo [a]pyrene treatment on ovarian follicles and ovarian surface epithelial cells in mice. Reprod Toxicol 2015; 58:24-32. [PMID: 26247513 DOI: 10.1016/j.reprotox.2015.07.080] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 06/29/2015] [Accepted: 07/31/2015] [Indexed: 02/06/2023]
Abstract
Polycyclic aromatic hydrocarbons, like benzo[a]pyrene (BaP), are ubiquitous environmental pollutants and potent ovarian toxicants. The transcription factor NRF2 is an important regulator of the cellular response to electrophilic toxicants like BaP and to oxidative stress. NRF2 regulates transcription of genes involved in the detoxification of reactive metabolites of BaP and reactive oxygen species. We therefore hypothesized that Nrf2-/- mice have accelerated ovarian aging and increased sensitivity to the ovarian toxicity of BaP. A single injection of BaP dose-dependently depleted ovarian follicles in Nrf2+/+ and Nrf2-/- mice, but the effects of BaP were not enhanced in the absence of Nrf2. Similarly, Nrf2-/- mice did not have increased ovarian BaP DNA adduct formation compared to Nrf2+/+ mice. Ovarian follicle numbers did not differ between peripubertal Nrf2-/- and Nrf2+/+ mice, but by middle age, Nrf2-/- mice had significantly fewer primordial follicles than Nrf2+/+ mice, consistent with accelerated ovarian aging.
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Affiliation(s)
- Jinhwan Lim
- Department of Medicine, University of California Irvine, USA
| | - Laura Ortiz
- Department of Medicine, University of California Irvine, USA
| | | | - Yvonne D Hoang
- Department of Medicine, University of California Irvine, USA
| | - Jesus Banuelos
- Department of Medicine, University of California Irvine, USA
| | | | - Jefferson Y Chan
- Department of Pathology and Laboratory Medicine, University of California Irvine, USA
| | - Ulrike Luderer
- Department of Medicine, University of California Irvine, USA; Department of Developmental and Cell Biology, University of California Irvine, USA.
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Václavíková R, Hughes DJ, Souček P. Microsomal epoxide hydrolase 1 (EPHX1): Gene, structure, function, and role in human disease. Gene 2015. [PMID: 26216302 DOI: 10.1016/j.gene.2015.07.071] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Microsomal epoxide hydrolase (EPHX1) is an evolutionarily highly conserved biotransformation enzyme for converting epoxides to diols. Notably, the enzyme is able to either detoxify or bioactivate a wide range of substrates. Mutations and polymorphic variants in the EPHX1 gene have been associated with susceptibility to several human diseases including cancer. This review summarizes the key knowledge concerning EPHX1 gene and protein structure, expression pattern and regulation, and substrate specificity. The relevance of EPHX1 for human pathology is especially discussed.
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Affiliation(s)
- Radka Václavíková
- Toxicogenomics Unit, National Institute of Public Health, Prague, Czech Republic
| | - David J Hughes
- Centre for Systems Medicine, Department of Physiology, Royal College of Surgeons in Ireland, Dublin 2, Ireland
| | - Pavel Souček
- Toxicogenomics Unit, National Institute of Public Health, Prague, Czech Republic; Biomedical Centre, Faculty of Medicine in Plzen, Charles University in Prague, Plzen, Czech Republic.
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Li T, Apte U. Bile Acid Metabolism and Signaling in Cholestasis, Inflammation, and Cancer. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2015; 74:263-302. [PMID: 26233910 DOI: 10.1016/bs.apha.2015.04.003] [Citation(s) in RCA: 182] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Bile acids are synthesized from cholesterol in the liver. Some cytochrome P450 (CYP) enzymes play key roles in bile acid synthesis. Bile acids are physiological detergent molecules, so are highly cytotoxic. They undergo enterohepatic circulation and play important roles in generating bile flow and facilitating biliary secretion of endogenous metabolites and xenobiotics and intestinal absorption of dietary fats and lipid-soluble vitamins. Bile acid synthesis, transport, and pool size are therefore tightly regulated under physiological conditions. In cholestasis, impaired bile flow leads to accumulation of bile acids in the liver, causing hepatocyte and biliary injury and inflammation. Chronic cholestasis is associated with fibrosis, cirrhosis, and eventually liver failure. Chronic cholestasis also increases the risk of developing hepatocellular or cholangiocellular carcinomas. Extensive research in the last two decades has shown that bile acids act as signaling molecules that regulate various cellular processes. The bile acid-activated nuclear receptors are ligand-activated transcriptional factors that play critical roles in the regulation of bile acid, drug, and xenobiotic metabolism. In cholestasis, these bile acid-activated receptors regulate a network of genes involved in bile acid synthesis, conjugation, transport, and metabolism to alleviate bile acid-induced inflammation and injury. Additionally, bile acids are known to regulate cell growth and proliferation, and altered bile acid levels in diseased conditions have been implicated in liver injury/regeneration and tumorigenesis. We will cover the mechanisms that regulate bile acid homeostasis and detoxification during cholestasis, and the roles of bile acids in the initiation and regulation of hepatic inflammation, regeneration, and carcinogenesis.
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Affiliation(s)
- Tiangang Li
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas, USA.
| | - Udayan Apte
- Department of Pharmacology, Toxicology and Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas, USA
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Oh S. Disturbance in testosterone production in leydig cells by polycyclic aromatic hydevrepocarbons. Dev Reprod 2015; 18:187-95. [PMID: 25949189 DOI: 10.12717/devrep.2014.18.4.187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 11/08/2014] [Accepted: 11/10/2014] [Indexed: 11/17/2022]
Abstract
Polycyclic aromatic hydevrepocarbons (PAHs), which are ubiquitous in the air, are present as volatile and particulate pollutants that result from incomplete combustion. Most PAHs have toxic, mutagenic, and/or carcinogenic properties. Among PAHs, benzo[a]pyrene (B[a]P) and dimethylbenz[a]anthracene (DMBA) are suspected endocrine disruptors. The testis is an important target for PAHs, yet effects on steroidogenesis in Leydig cells are yet to be ascertained. Particularly, disruption of testosterone production by these chemicals can result in serious defects in male reproduction. Exposure to B[a]P reduced serum and intratesticular fluid testosterone levels in rats. Of note, the testosterone level reductions were accompanied by decreased steroidogenic acute regulatory protein (StAR) and 3β-hydevrepoxysteroid dehydevrepogenase isomerase (3β-HSD) expression in Leydig cells. B[a]P exposure can decrease epididymal sperm quality, possibly by disturbing the testosterone level. StAR may be a key steroidogenic protein that is targeted by B[a]P or other PAHs.
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Affiliation(s)
- Seunghoon Oh
- Dept. of Physiology, College of Medicine, Dankook University, Cheonan 330-714, Korea
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Abstract
Polycyclic aromatic hydrocarbons (PAHs), which are ubiquitous in the air, are
present as volatile and particulate pollutants that result from incomplete
combustion. Most PAHs have toxic, mutagenic, and/or carcinogenic properties.
Among PAHs, benzo[a]pyrene (B[a]P) and dimethylbenz[a]anthracene (DMBA) are
suspected endocrine disruptors. The testis is an important target for PAHs, yet
effects on steroidogenesis in Leydig cells are yet to be ascertained.
Particularly, disruption of testosterone production by these chemicals can
result in serious defects in male reproduction. Exposure to B[a]P reduced serum
and intratesticular fluid testosterone levels in rats. Of note, the testosterone
level reductions were accompanied by decreased steroidogenic acute regulatory
protein (StAR) and 3β-hydroxysteroid dehydrogenase isomerase
(3β-HSD) expression in Leydig cells. B[a]P exposure can decrease
epididymal sperm quality, possibly by disturbing the testosterone level. StAR
may be a key steroidogenic protein that is targeted by B[a]P or other PAHs.
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Affiliation(s)
- Seunghoon Oh
- Dept. of Physiology, College of Medicine, Dankook University, Cheonan 330-714, Korea
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30
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Rothmund L, Shehata M, Van Landuyt KL, Schweikl H, Carell T, Geurtsen W, Hellwig E, Hickel R, Reichl FX, Högg C. Release and protein binding of components from resin based composites in native saliva and other extraction media. Dent Mater 2015; 31:496-504. [DOI: 10.1016/j.dental.2015.01.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 01/24/2015] [Accepted: 01/28/2015] [Indexed: 01/06/2023]
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Abstract
Bile acids are the end products of cholesterol catabolism. Hepatic bile acid synthesis accounts for a major fraction of daily cholesterol turnover in humans. Biliary secretion of bile acids generates bile flow and facilitates hepatobiliary secretion of lipids, lipophilic metabolites, and xenobiotics. In the intestine, bile acids are essential for the absorption, transport, and metabolism of dietary fats and lipid-soluble vitamins. Extensive research in the last 2 decades has unveiled new functions of bile acids as signaling molecules and metabolic integrators. The bile acid-activated nuclear receptors farnesoid X receptor, pregnane X receptor, constitutive androstane receptor, vitamin D receptor, and G protein-coupled bile acid receptor play critical roles in the regulation of lipid, glucose, and energy metabolism, inflammation, and drug metabolism and detoxification. Bile acid synthesis exhibits a strong diurnal rhythm, which is entrained by fasting and refeeding as well as nutrient status and plays an important role for maintaining metabolic homeostasis. Recent research revealed an interaction of liver bile acids and gut microbiota in the regulation of liver metabolism. Circadian disturbance and altered gut microbiota contribute to the pathogenesis of liver diseases, inflammatory bowel diseases, nonalcoholic fatty liver disease, diabetes, and obesity. Bile acids and their derivatives are potential therapeutic agents for treating metabolic diseases of the liver.
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Affiliation(s)
- Tiangang Li
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas (T.L.); and Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio (J.Y.L.C.)
| | - John Y L Chiang
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas (T.L.); and Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, Ohio (J.Y.L.C.)
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Ganesan S, Nteeba J, Keating AF. Enhanced susceptibility of ovaries from obese mice to 7,12-dimethylbenz[a]anthracene-induced DNA damage. Toxicol Appl Pharmacol 2014; 281:203-10. [PMID: 25448685 DOI: 10.1016/j.taap.2014.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 10/03/2014] [Accepted: 10/05/2014] [Indexed: 01/10/2023]
Abstract
7,12-Dimethylbenz[a]anthracene (DMBA) depletes ovarian follicles and induces DNA damage in extra-ovarian tissues, thus, we investigated ovarian DMBA-induced DNA damage. Additionally, since obesity is associated with increased offspring birth defect incidence, we hypothesized that a DMBA-induced DNA damage response (DDR) is compromised in ovaries from obese females. Wild type (lean) non agouti (a/a) and KK.Cg-Ay/J heterozygote (obese) mice were dosed with sesame oil or DMBA (1mg/kg; intraperitoneal injection) at 18weeks of age, for 14days. Total ovarian RNA and protein were isolated and abundance of Ataxia telangiectasia mutated (Atm), X-ray repair complementing defective repair in Chinese hamster cells 6 (Xrcc6), breast cancer type 1 (Brca1), Rad 51 homolog (Rad51), poly [ADP-ribose] polymerase 1 (Parp1) and protein kinase, DNA-activated, catalytic polypeptide (Prkdc) were quantified by RT-PCR or Western blot. Phosphorylated histone H2AX (γH2AX) level was determined by Western blotting. Obesity decreased (P<0.05) basal protein abundance of PRKDC and BRCA1 proteins but increased (P<0.05) γH2AX and PARP1 proteins. Ovarian ATM, XRCC6, PRKDC, RAD51 and PARP1 proteins were increased (P<0.05) by DMBA exposure in lean mice. A blunted DMBA-induced increase (P<0.05) in XRCC6, PRKDC, RAD51 and BRCA1 was observed in ovaries from obese mice, relative to lean counterparts. Taken together, DMBA exposure induced γH2AX as well as the ovarian DDR, supporting that DMBA causes ovarian DNA damage. Additionally, ovarian DDR was partially attenuated in obese females raising concern that obesity may be an additive factor during chemical-induced ovotoxicity.
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Affiliation(s)
- Shanthi Ganesan
- Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
| | - Jackson Nteeba
- Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
| | - Aileen F Keating
- Department of Animal Science, Iowa State University, Ames, IA 50011, USA.
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El-Sherbeni AA, El-Kadi AOS. The role of epoxide hydrolases in health and disease. Arch Toxicol 2014; 88:2013-32. [PMID: 25248500 DOI: 10.1007/s00204-014-1371-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 09/11/2014] [Indexed: 01/09/2023]
Abstract
Epoxide hydrolases (EH) are ubiquitously expressed in all living organisms and in almost all organs and tissues. They are mainly subdivided into microsomal and soluble EH and catalyze the hydration of epoxides, three-membered-cyclic ethers, to their corresponding dihydrodiols. Owning to the high chemical reactivity of xenobiotic epoxides, microsomal EH is considered protective enzyme against mutagenic and carcinogenic initiation. Nevertheless, several endogenously produced epoxides of fatty acids function as important regulatory mediators. By mediating the formation of cytotoxic dihydrodiol fatty acids on the expense of cytoprotective epoxides of fatty acids, soluble EH is considered to have cytotoxic activity. Indeed, the attenuation of microsomal EH, achieved by chemical inhibitors or preexists due to specific genetic polymorphisms, is linked to the aggravation of the toxicity of xenobiotics, as well as the risk of cancer and inflammatory diseases, whereas soluble EH inhibition has been emerged as a promising intervention against several diseases, most importantly cardiovascular, lung and metabolic diseases. However, there is reportedly a significant overlap in substrate selectivity between microsomal and soluble EH. In addition, microsomal and soluble EH were found to have the same catalytic triad and identical molecular mechanism. Consequently, the physiological functions of microsomal and soluble EH are also overlapped. Thus, studying the biological effects of microsomal or soluble EH alterations needs to include the effects on both the metabolism of reactive metabolites, as well as epoxides of fatty acids. This review focuses on the multifaceted role of EH in the metabolism of xenobiotic and endogenous epoxides and the impact of EH modulations.
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Affiliation(s)
- Ahmed A El-Sherbeni
- Faculty of Pharmacy and Pharmaceutical Sciences, 2142J Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, AB, T6G 2E1, Canada
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Chen JY, Chen WN, Jiao BY, Lin WS, Wu YL, Liu LL, Lin X. Hepatitis B spliced protein (HBSP) promotes the carcinogenic effects of benzo [alpha] pyrene by interacting with microsomal epoxide hydrolase and enhancing its hydrolysis activity. BMC Cancer 2014; 14:282. [PMID: 24758376 PMCID: PMC4002904 DOI: 10.1186/1471-2407-14-282] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 04/16/2014] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The risk of hepatocellular carcinoma (HCC) increases in chronic hepatitis B surface antigen (HBsAg) carriers who often have concomitant increase in the levels of benzo[alpha]pyrene-7,8-diol-9,10-epoxide(±) (BPDE)-DNA adduct in liver tissues, suggesting a possible co-carcinogenesis of Hepatitis B virus (HBV) and benzo[alpha]pyrene in HCC; however the exact mechanisms involved are unclear. METHODS The interaction between hepatitis B spliced protein (HBSP) and microsomal epoxide hydrolase (mEH) was confirmed using GST pull-down, co-immunoprecipitation and mammalian two-hybrid assay; the effects of HBSP on mEH-mediated B[alpha]P metabolism was examined by high performance liquid chromatography (HPLC); and the influences of HBSP on B[alpha]P carcinogenicity were evaluated by bromodeoxyuridine cell proliferation, anchorage-independent growth and tumor xenograft. RESULTS HBSP could interact with mEH in vitro and in vivo, and this interaction was mediated by the N terminal 47 amino acid residues of HBSP. HBSP could greatly enhance the hydrolysis activity of mEH in cell-free mouse liver microsomes, thus accelerating the metabolism of benzo[alpha]pyrene to produce more ultimate carcinnogen, BPDE, and this effect of HBSP requires the intact HBSP molecule. Expression of HBSP significantly increased the formation of BPDE-DNA adduct in benzo[alpha]pyrene-treated Huh-7 hepatoma cells, and this enhancement was blocked by knockdown of mEH. HBSP could enhance the cell proliferation, accelerate the G1/S transition, and promote cell transformation and tumorigenesis of B[alpha]P-treated Huh-7 hepatoma cells. CONCLUSIONS Our results demonstrated that HBSP could promote carcinogenic effects of B[alpha]P by interacting with mEH and enhancing its hydrolysis activity.
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Affiliation(s)
| | | | | | | | | | | | - Xu Lin
- Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Research Center of Molecular Medicine, Fujian Medical University, Fuzhou, Fujian 350004, P,R, China.
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Su S, Yang X, Omiecinski CJ. Intronic DNA elements regulate Nrf2 chemical responsiveness of the human microsomal epoxide hydrolase gene (EPHX1) through a far upstream alternative promoter. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:493-505. [PMID: 24704207 DOI: 10.1016/j.bbagrm.2014.03.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/16/2014] [Accepted: 03/26/2014] [Indexed: 10/25/2022]
Abstract
In humans, microsomal epoxide hydrolase (mEH) contributes important biological functions that underlie both detoxification and bioactivation fates arising from exposures to foreign chemicals. Previously, we discovered that human mEH gene transcription is initiated from alternative promoters. The respective transcripts are programmed with tissue specificity and the upstream E1b promoter contributes predominantly to mEH expression. The results presented demonstrate that exposures to the Nrf2 activators, sulforaphane (SFN) and tert-butylhydroquinone (tBHQ), markedly activate E1b transcription in human lung and liver cells. Genomic analyses identified two major DNase I hypersensitive regions (HS-1 and HS-2) within the ~15 kb intervening sequence separating E1b from the downstream E1 promoter. In BEAS-2B cells, the Nrf2 effectors, SFN and tBHQ, selectively activated the more distal HS-2 through an antioxidant response element (ARE). An activator protein 1/12-O-tetradecanoylphorbol-13-acetate interaction was further identified within the HS-2 enhancer that functioned to additionally contribute to ARE-mediated induction responsiveness of the E1b promoter. The results demonstrate that ARE modulation, integrated with additional transcriptional complexes, regulates the tissue-specific expression of mEH and that these processes likely coordinate both the protective and bioactivation functions contributed by mEH activities in human tissues.
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Affiliation(s)
- Shengzhong Su
- Center for Molecular Toxicology & Carcinogenesis, The Pennsylvania State University, 101 Life Sciences Bldg, University Park, PA 16802, USA
| | - Xi Yang
- Center for Molecular Toxicology & Carcinogenesis, The Pennsylvania State University, 101 Life Sciences Bldg, University Park, PA 16802, USA
| | - Curtis J Omiecinski
- Center for Molecular Toxicology & Carcinogenesis, The Pennsylvania State University, 101 Life Sciences Bldg, University Park, PA 16802, USA.
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Nteeba J, Ganesan S, Keating AF. Impact of obesity on ovotoxicity induced by 7,12-dimethylbenz[a]anthracene in mice. Biol Reprod 2014; 90:68. [PMID: 24501177 DOI: 10.1095/biolreprod.113.114215] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Insulin, elevated during obesity, regulates xenobiotic biotransformation enzymes, potentially through phosphatidylinositol 3-kinase (PI3K) signaling, in extraovarian tissues. PI3K regulates oocyte viability, follicular activation, and ovarian chemical biotransformation. 7,12-Dimethylbenz[a]anthracene (DMBA), a carcinogen and ovotoxicant, destroys all stages of follicles, leading to premature ovarian failure. Obesity has been reported to promote DMBA-induced tumors, but it remains unknown whether obesity affects ovarian xenobiotic metabolism. Therefore, we investigated ovarian expression of xenobiotic metabolism genes-microsomal epoxide hydrolase (Ephx1), glutathione S-transferase (GST) class Pi (Gstp1) and class mu 1 (Gstm1), and PI3K-signaling members (protein kinase B [AKT] alpha [Akt1], beta [Akt2], and the forkhead transcription factor subfamily 3 [Foxo3])-in lean and obese female mice after DMBA exposure (1 mg/kg; intraperitoneal injection for 14 days). Relative to lean, obese mice had decreased (P < 0.05) healthy primordial and primary follicle numbers but increased (P < 0.05) secondary and preovulatory follicles numbers. Obesity increased (P < 0.05) Akt1, Akt2, Gstm1, and Ephx1 mRNA and pAKT(Ser473/Thr308), GSTM1, GSTP1, and EPHX1 protein levels. DMBA decreased (P < 0.05) ovarian weight in lean and obese mice, however, obese DMBA-treated females had a greater reduction (P < 0.05) in ovarian weight. In both lean and obese mice, DMBA decreased (P < 0.05) all stages of healthy follicle numbers, increased Gstp1 and Ephx1 mRNA as well as GSTM1, GSTP1, and EPHX1 protein levels, and decreased Akt1 and Akt2 mRNA as well as pAKT(Ser473) or pAKT(Thr308), FOXO3, and pFOXO3(Ser253) protein expression. There was an additive effect between obesity and DMBA exposure for increased Gstm1 and Ephx1 mRNA as well as GSTM1 and EPHX1 protein expression.
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Affiliation(s)
- Jackson Nteeba
- Department of Animal Science, Iowa State University, Ames, Iowa
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Acute 7,12-dimethylbenz[a]anthracene exposure causes differential concentration-dependent follicle depletion and gene expression in neonatal rat ovaries. Toxicol Appl Pharmacol 2014; 276:179-87. [PMID: 24576726 DOI: 10.1016/j.taap.2014.02.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 02/06/2014] [Accepted: 02/14/2014] [Indexed: 11/22/2022]
Abstract
Chronic exposure to the polycyclic aromatic hydrocarbon 7,12-dimethylbenz[a]anthracene (DMBA), generated during combustion of organic matter including cigarette smoke, depletes all ovarian follicle types in the mouse and rat, and in vitro models mimic this effect. To investigate the mechanisms involved in follicular depletion during acute DMBA exposure, two concentrations of DMBA at which follicle depletion has (75 nM) and has not (12.5 nM) been observed were investigated. Postnatal day four F344 rat ovaries were maintained in culture for four days before a single exposure to vehicle control (1% DMSO; CT) or DMBA (12 nM; low-concentration or 75 nM; high-concentration). After four or eight additional days of culture, DMBA-induced follicle depletion was evaluated via follicle enumeration. Relative to control, DMBA did not affect follicle numbers after 4 days of exposure, but induced large primary follicle loss at both concentrations after 8 days; while, the low-concentration DMBA also caused secondary follicle depletion. Neither concentration affected primordial or small primary follicle number. RNA was isolated and quantitative RT-PCR performed prior to follicle loss to measure mRNA levels of genes involved in xenobiotic metabolism (Cyp2e1, Gstmu, Gstpi, Ephx1), autophagy (Atg7, Becn1), oxidative stress response (Sod1, Sod2) and the phosphatidylinositol 3-kinase (PI3K) pathway (Kitlg, cKit, Akt1) 1, 2 and 4 days after exposure. With the exception of Atg7 and cKit, DMBA increased (P < 0.05) expression of all genes investigated. Also, BECN1 and pAKT(Thr308) protein levels were increased while cKIT was decreased by DMBA exposure. Taken together, these results suggest an increase in DMBA bioactivation, add to the mechanistic understanding of DMBA-induced ovotoxicity and raise concern regarding female low concentration DMBA exposures.
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Hrycay E, Forrest D, Liu L, Wang R, Tai J, Deo A, Ling V, Bandiera S. Hepatic bile acid metabolism and expression of cytochrome P450 and related enzymes are altered in Bsep (-/-) mice. Mol Cell Biochem 2014; 389:119-32. [PMID: 24399466 DOI: 10.1007/s11010-013-1933-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 12/18/2013] [Indexed: 02/06/2023]
Abstract
The bile salt export pump (BSEP/Bsep; gene symbol ABCB11/Abcb11) translocates bile salts across the hepatocyte canalicular membrane into bile in humans and mice. In humans, mutations in the ABCB11 gene cause a severe childhood liver disease known as progressive familial intrahepatic cholestasis type 2. Targeted inactivation of mouse Bsep produces milder persistent cholestasis due to detoxification of bile acids through hydroxylation and alternative transport pathways. The purpose of the present study was to determine whether functional expression of hepatic cytochrome P450 (CYP) and microsomal epoxide hydrolase (mEH) is altered by Bsep inactivation in mice and whether bile acids regulate CYP and mEH expression in Bsep (-/-) mice. CYP expression was determined by measuring protein levels of Cyp2b, Cyp2c and Cyp3a enzymes and CYP-mediated activities including lithocholic acid hydroxylation, testosterone hydroxylation and alkoxyresorufin O-dealkylation in hepatic microsomes prepared from female and male Bsep (-/-) mice fed a normal or cholic acid (CA)-enriched diet. The results indicated that hepatic lithocholic acid hydroxylation was catalyzed by Cyp3a/Cyp3a11 enzymes in Bsep (-/-) mice and that 3-ketocholanoic acid and murideoxycholic acid were major metabolites. CA feeding of Bsep (-/-) mice increased hepatic Cyp3a11 protein levels and Cyp3a11-mediated testosterone 2β-, 6β-, and 15β-hydroxylation activities, increased Cyp2b10 protein levels and Cyp2b10-mediated benzyloxyresorufin O-debenzylation activity, and elevated Cyp2c29 and mEH protein levels. We propose that bile acids upregulate expression of hepatic Cyp3a11, Cyp2b10, Cyp2c29 and mEH in Bsep (-/-) mice and that Cyp3a11 and multidrug resistance-1 P-glycoproteins (Mdr1a/1b) are vital components of two distinct pathways utilized by mouse hepatocytes to expel bile acids.
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Affiliation(s)
- Eugene Hrycay
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC, V6T1Z3, Canada
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Su S, Omiecinski CJ. Sp1 and Sp3 transcription factors regulate the basal expression of human microsomal epoxide hydrolase (EPHX1) through interaction with the E1b far upstream promoter. Gene 2013; 536:135-44. [PMID: 24315822 DOI: 10.1016/j.gene.2013.11.053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 10/28/2013] [Accepted: 11/18/2013] [Indexed: 11/24/2022]
Abstract
Microsomal epoxide hydrolase (mEH, EPHX1) is a critical biotransformation enzyme, catalyzing the metabolism of many xenobiotics. Human mEH is transcribed using alternative promoters. The upstream E1 promoter is active in liver while the far upstream E1b promoter drives the expression of mEH in all tissues, including liver. Although several liver-specific transcription factors have been identified in the regulation of E1 transcription, little is known regarding the mechanisms of E1b transcriptional regulation. Genome-wide mapping of DNase I hypersensitive sites revealed an open chromatin region between nucleotide -300 upstream and +400 downstream of E1b. This area coincides with a previously described promoter region responsible for maintaining high basal promoter activity. In silico analysis of this location revealed several Sp1/Sp3 binding sites. Site-directed mutagenesis of these motifs suppressed the transactivation activity of the E1b proximal promoter, indicating their importance as contributors to E1b promoter regulation. Further, E1b promoter activities were increased significantly following Sp1 and Sp3 overexpression, while Mithramycin A, a selective Sp1 inhibitor, reduced the promoter activities. EMSA studies demonstrated that Sp1 bound to two putative Sp1/Sp3 binding sites. ChIP analysis confirmed that both endogenous Sp1 and Sp3 were bound to the proximal promoter region of E1b. Knockdown of Sp1 expression using siRNA did not alter the endogenous E1b transcriptional level, while knockdown of Sp3 greatly decreased E1b expression in different human cell lines. Taken together, these results support the concept that Sp1 and Sp3 are functionally involved as transcriptional integrators regulating the basal expression of the derived mEH E1b variant transcript.
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Affiliation(s)
- Shengzhong Su
- Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, 101 Life Sciences Bldg, University Park, PA 16802, USA
| | - Curtis J Omiecinski
- Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, 101 Life Sciences Bldg, University Park, PA 16802, USA.
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Nguyen HL, Yang X, Omiecinski CJ. Expression of a novel mRNA transcript for human microsomal epoxide hydrolase (EPHX1) is regulated by short open reading frames within its 5'-untranslated region. RNA (NEW YORK, N.Y.) 2013; 19:752-66. [PMID: 23564882 PMCID: PMC3683910 DOI: 10.1261/rna.037036.112] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Microsomal epoxide hydrolase (mEH, EPHX1) is a critical xenobiotic-metabolizing enzyme, catalyzing both detoxification and bioactivation reactions that direct the disposition of chemical epoxides, including the carcinogenic metabolites of several polycyclic aromatic hydrocarbons. Recently, we discovered that a previously unrecognized and primate-specific EPHX1 transcript, termed E1-b, was actually the predominant driver of EPHX1 expression in all human tissues. In this study, we identify another human EPHX1 transcript, designated as E1-b'. Unusually, both the E1-b and E1-b' mRNA transcripts are generated from the use of a far upstream gene promoter, localized ∼18.5 kb 5'-upstream of the EPHX1 protein-coding region. Although expressed at comparatively lower levels than E1-b, the novel E1-b' transcript is readily detected in all tissues examined, with highest levels maintained in human ovary. The E1-b' mRNA possesses unusual functional features in its 5'-untranslated region, including a GC-rich leader sequence and two upstream AUGs that encode for short peptides of 26 and 17 amino acids in length, respectively. Results from in vitro transcription/translation assays and direct transfection in mammalian cells of either the E1-b' transcript or the encoded peptides demonstrated that the E1-b' upstream open reading frames (uORFs) are functional, with their presence markedly inhibiting the translation of EPHX1 protein, both in cis and in trans configurations. These unique uORF peptides exhibit no homology to any other known uORF sequences but likely function to mediate post-transcription regulation of EPHX1 and perhaps more broadly as translational regulators in human cells.
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WESSEL NATHALIE, DÛ-LACOSTE MARIELE, BUDZINSKI HÉLÈNE, BURGEOT THIERRY, AKCHA FARIDA. UPLC MS/MS Quantification of Primary Metabolites of Benzo[a]pyrene and Fluoranthene Produced In Vitro by Sole (Solea solea) Liver Microsomal Activation. Polycycl Aromat Compd 2013. [DOI: 10.1080/10406638.2012.725197] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Bhattacharya P, Keating AF. Protective role for ovarian glutathione S-transferase isoform pi during 7,12-dimethylbenz[a]anthracene-induced ovotoxicity. Toxicol Appl Pharmacol 2012; 260:201-8. [PMID: 22406437 PMCID: PMC3319246 DOI: 10.1016/j.taap.2012.02.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 02/20/2012] [Accepted: 02/21/2012] [Indexed: 02/06/2023]
Abstract
7,12-Dimethylbenz[a]anthracene (DMBA) destroys ovarian follicles at all developmental stages. This study investigated a role for the glutathione S-transferase (Gst) isoforms alpha (a), mu (m) and pi (p) and the transcription factors, Ahr and Nrf2, during DMBA-induced ovotoxicity, and their regulation by phosphatidylinositol-3 kinase (PI3K) signaling. Negative regulation of JNK by GSTP during DMBA exposure was also studied. Post-natal day (PND) 4 Fischer 344 rat ovaries were exposed to vehicle control (1% DMSO)±DMBA (1 μM) or vehicle control (1% DMSO)±LY294002 (PI3K inhibitor; 20 μM) for 1, 2, 4, or 6 days. Total RNA or protein was isolated, followed by RT-PCR or Western blotting to determine mRNA or protein level, respectively. Immunoprecipitation using an anti-GSTP antibody was performed to determine interaction between GSTP and JNK, followed by Western blotting to determine JNK and p-c-Jun protein level. DMBA had no impact on Gsta, Gstm or Nrf2 mRNA level, but increased Gstp mRNA and protein after 2 days. Ahr mRNA and protein increased after 2 and 4 days of DMBA exposure, respectively and DMBA increased NRF2 protein level after 4 days. JNK bound to GSTP was increased during DMBA exposure, with a concomitant decrease in unbound JNK and p-c-Jun. Ahr and Gstp mRNA were decreased (2 days) and increased (4 days) by PI3K inhibition, while Gstm mRNA increased (P<0.05) after both time points, and there was no effect on Nrf2 mRNA. PI3K inhibition increased AHR, NRF2 and GSTP protein level. These findings support involvement of ovarian GSTP during DMBA exposure, and indicate a regulatory role for the PI3K signaling pathway on ovarian xenobiotic metabolism gene expression.
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Affiliation(s)
| | - Aileen F. Keating
- Department of Animal Science, Iowa State University, Ames, IA 50011, USA
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Bhattacharya P, Keating AF. Impact of environmental exposures on ovarian function and role of xenobiotic metabolism during ovotoxicity. Toxicol Appl Pharmacol 2012; 261:227-35. [PMID: 22531813 DOI: 10.1016/j.taap.2012.04.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 04/04/2012] [Accepted: 04/05/2012] [Indexed: 11/19/2022]
Abstract
The mammalian ovary is a heterogeneous organ and contains oocyte-containing follicles at varying stages of development. The most immature follicular stage, the primordial follicle, comprises the ovarian reserve and is a finite number, defined at the time of birth. Depletion of all follicles within the ovary leads to reproductive senescence, known as menopause. A number of chemical classes can destroy follicles, thus hastening entry into the menopausal state. The ovarian response to chemical exposure can determine the extent of ovotoxicity that occurs. Enzymes capable of bioactivating as well as detoxifying xenobiotics are expressed in the ovary and their impact on ovotoxicity has been partially characterized for trichloroethylene, 7,12-dimethylbenz[a]anthracene, and 4-vinylcyclohexene. This review will discuss those studies, as well as illustrate where knowledge gaps remain for chemicals that have also been established as ovotoxicants.
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44
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Modi BG, Neustadter J, Binda E, Lewis J, Filler RB, Roberts SJ, Kwong BY, Reddy S, Overton JD, Galan A, Tigelaar R, Cai L, Fu P, Shlomchik M, Kaplan DH, Hayday A, Girardi M. Langerhans cells facilitate epithelial DNA damage and squamous cell carcinoma. Science 2012; 335:104-8. [PMID: 22223807 PMCID: PMC3753811 DOI: 10.1126/science.1211600] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Polyaromatic hydrocarbons (PAHs) are prevalent, potent carcinogens, and 7,12-dimethylbenz[a]anthracene (DMBA) is a model PAH widely used to study tumorigenesis. Mice lacking Langerhans cells (LCs), a signatory epidermal dendritic cell (DC), are protected from cutaneous chemical carcinogenesis, independent of T cell immunity. Investigation of the underlying mechanism revealed that LC-deficient skin was relatively resistant to DMBA-induced DNA damage. LCs efficiently metabolized DMBA to DMBA-trans-3,4-diol, an intermediate proximal to oncogenic Hras mutation, and DMBA-treated LC-deficient skin contained significantly fewer Hras mutations. Moreover, DMBA-trans-3,4-diol application bypassed tumor resistance in LC-deficient mice. Additionally, the genotoxic impact of DMBA on human keratinocytes was significantly increased by prior incubation with human-derived LC. Thus, tissue-associated DC can enhance chemical carcinogenesis via PAH metabolism, highlighting the complex relation between immune cells and carcinogenesis.
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MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene/analogs & derivatives
- 9,10-Dimethyl-1,2-benzanthracene/metabolism
- 9,10-Dimethyl-1,2-benzanthracene/toxicity
- Animals
- Aryl Hydrocarbon Hydroxylases/metabolism
- Carcinogens/metabolism
- Carcinogens/toxicity
- Carcinoma, Squamous Cell/chemically induced
- Carcinoma, Squamous Cell/metabolism
- Cell Transformation, Neoplastic
- Cells, Cultured
- Cytochrome P-450 CYP1A1/metabolism
- Cytochrome P-450 CYP1B1
- DNA Damage
- Genes, ras
- Humans
- Keratinocytes/metabolism
- Keratinocytes/pathology
- Langerhans Cells/immunology
- Langerhans Cells/metabolism
- Mice
- Mice, Transgenic
- Skin Neoplasms/chemically induced
- Skin Neoplasms/metabolism
- T-Lymphocytes/immunology
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Affiliation(s)
- Badri G. Modi
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Jason Neustadter
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Elisa Binda
- Peter Gorer Department of Immunobiology, King’s College, the Comprehensive Biomedical Research Centre of Guy’s and St. Thomas’ Hospitals, London SE1 9RT, UK
- London Research Institute, Cancer Research UK (CRUK), London WC2A, UK
| | - Julia Lewis
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Renata B. Filler
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Scott J. Roberts
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Bernice Y. Kwong
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Swapna Reddy
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - John D. Overton
- Department of Genetics and Yale Center for Genome Analysis, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Anjela Galan
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Robert Tigelaar
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Lining Cai
- Biotranex, Monmouth Junction, NJ 08852, USA
| | - Peter Fu
- National Center for Toxicological Research, United States Food and Drug Administration (FDA), Jefferson, AR 72079, USA
| | - Mark Shlomchik
- Department of Laboratory Medicine and Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Daniel H. Kaplan
- Department of Dermatology, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Immunobiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Adrian Hayday
- Peter Gorer Department of Immunobiology, King’s College, the Comprehensive Biomedical Research Centre of Guy’s and St. Thomas’ Hospitals, London SE1 9RT, UK
- London Research Institute, Cancer Research UK (CRUK), London WC2A, UK
| | - Michael Girardi
- Department of Dermatology, Yale University School of Medicine, New Haven, CT 06520, USA
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45
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Synthesis and structure–activity relationship of acylthiourea derivatives as inhibitors of microsomal epoxide hydrolase. Med Chem Res 2012. [DOI: 10.1007/s00044-011-9953-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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46
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Radiation-induced carcinogenesis: mechanistically based differences between gamma-rays and neutrons, and interactions with DMBA. PLoS One 2011; 6:e28559. [PMID: 22194850 PMCID: PMC3237439 DOI: 10.1371/journal.pone.0028559] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 11/10/2011] [Indexed: 12/29/2022] Open
Abstract
Different types of ionizing radiation produce different dependences of cancer risk on radiation dose/dose rate. Sparsely ionizing radiation (e.g. γ-rays) generally produces linear or upwardly curving dose responses at low doses, and the risk decreases when the dose rate is reduced (direct dose rate effect). Densely ionizing radiation (e.g. neutrons) often produces downwardly curving dose responses, where the risk initially grows with dose, but eventually stabilizes or decreases. When the dose rate is reduced, the risk increases (inverse dose rate effect). These qualitative differences suggest qualitative differences in carcinogenesis mechanisms. We hypothesize that the dominant mechanism for induction of many solid cancers by sparsely ionizing radiation is initiation of stem cells to a pre-malignant state, but for densely ionizing radiation the dominant mechanism is radiation-bystander-effect mediated promotion of already pre-malignant cell clone growth. Here we present a mathematical model based on these assumptions and test it using data on the incidence of dysplastic growths and tumors in the mammary glands of mice exposed to high or low dose rates of γ-rays and neutrons, either with or without pre-treatment with the chemical carcinogen 7,12-dimethylbenz-alpha-anthracene (DMBA). The model provides a mechanistic and quantitative explanation which is consistent with the data and may provide useful insight into human carcinogenesis.
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Burnett-Hartman AN, Newcomb PA, Mandelson MT, Adams SV, Wernli KJ, Shadman M, Wurscher MA, Makar KW. Colorectal polyp type and the association with charred meat consumption, smoking, and microsomal epoxide hydrolase polymorphisms. Nutr Cancer 2011; 63:583-92. [PMID: 21598178 DOI: 10.1080/01635581.2011.553021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We determined the association between charred meat consumption, cigarette smoking, microsomal epoxide hydrolase (mEH) polymorphisms (rs1051740 and rs2234922), and colorectal adenomas and hyperplastic polyps (HPs) and explored gene-environment interactions. Men and women with colorectal adenomas (n = 519), HPs (n = 691), or concurrently with both types of polyps (n = 227) and polyp-free controls (n = 772) receiving a colonoscopy from December 2004 to September 2007 were recruited. Participants completed telephone interviews and provided buccal cell samples; genotyping of mEH was completed using Taqman assays. We conducted polytomous regression and calculated odd ratios (OR) and 95% confidence intervals. Interactions were evaluated using Wald chi-square tests. Consumption of >3 servings of charred meat per week was associated with distal HPs (OR = 2.0, 1.2-3.4) but not adenomas nor either type of proximal polyp. Heavy cigarette smoking (≥ 22 pack-years) was associated with an increased risk for colorectal adenomas (OR = 1.7, 95% CI: 1.2-2.4), HPs (OR = 2.4, 95% CI: 1.7-3.3), and both types (OR = 2.8, 95% CI: 1.8-4.3) with the strongest association for distal polyps. There was no association between mEH genotype and colorectal polyps, nor were any statistically significant gene-environment interactions identified. Future investigation of BaP exposure and colorectal neoplasia should analyze whether associations are dependent upon anatomic location.
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Boverhof DR, Chamberlain MP, Elcombe CR, Gonzalez FJ, Heflich RH, Hernández LG, Jacobs AC, Jacobson-Kram D, Luijten M, Maggi A, Manjanatha MG, Benthem JV, Gollapudi BB. Transgenic animal models in toxicology: historical perspectives and future outlook. Toxicol Sci 2011; 121:207-33. [PMID: 21447610 DOI: 10.1093/toxsci/kfr075] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Transgenic animal models are powerful tools for developing a more detailed understanding on the roles of specific genes in biological pathways and systems. Applications of these models have been made within the field of toxicology, most notably for the screening of mutagenic and carcinogenic potential and for the characterization of toxic mechanisms of action. It has long been a goal of research toxicologists to use the data from these models to refine hazard identification and characterization to better inform human health risk assessments. This review provides an overview on the applications of transgenic animal models in the assessment of mutagenicity and carcinogenicity, their use as reporter systems, and as tools for understanding the roles of xenobiotic-metabolizing enzymes and biological receptors in the etiology of chemical toxicity. Perspectives are also shared on the future outlook for these models in toxicology and risk assessment and how transgenic technologies are likely to be an integral tool for toxicity testing in the 21st century.
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Affiliation(s)
- Darrell R Boverhof
- Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, Michigan 48674, USA.
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Morisseau C, Bernay M, Escaich A, Sanborn JR, Lango J, Hammock BD. Development of fluorescent substrates for microsomal epoxide hydrolase and application to inhibition studies. Anal Biochem 2011; 414:154-62. [PMID: 21371418 DOI: 10.1016/j.ab.2011.02.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 02/23/2011] [Accepted: 02/25/2011] [Indexed: 10/18/2022]
Abstract
The microsomal epoxide hydrolase (mEH) plays a significant role in the metabolism of numerous xenobiotics. In addition, it has a potential role in sexual development and bile acid transport, and it is associated with a number of diseases such as emphysema, spontaneous abortion, eclampsia, and several forms of cancer. Toward developing chemical tools to study the biological role of mEH, we designed and synthesized a series of absorbent and fluorescent substrates. The highest activity for both rat and human mEH was obtained with the fluorescent substrate cyano(6-methoxy-naphthalen-2-yl)methyl glycidyl carbonate (11). An in vitro inhibition assay using this substrate ranked a series of known inhibitors similarly to the assay that used radioactive cis-stilbene oxide but with a greater discrimination between inhibitors. These results demonstrate that the new fluorescence-based assay is a useful tool for the discovery of structure-activity relationships among mEH inhibitors. Furthermore, this substrate could also be used for the screening chemical library with high accuracy and with a Z' value of approximately 0.7. This new assay permits a significant decrease in labor and cost and also offers the advantage of a continuous readout. However, it should not be used with crude enzyme preparations due to interfering reactions.
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Affiliation(s)
- Christophe Morisseau
- Department of Entomology and Cancer Center, University of California - Davis, 95616, USA.
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50
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Stieger B. The role of the sodium-taurocholate cotransporting polypeptide (NTCP) and of the bile salt export pump (BSEP) in physiology and pathophysiology of bile formation. Handb Exp Pharmacol 2011:205-59. [PMID: 21103971 DOI: 10.1007/978-3-642-14541-4_5] [Citation(s) in RCA: 198] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bile formation is an important function of the liver. Bile salts are a major constituent of bile and are secreted by hepatocytes into bile and delivered into the small intestine, where they assist in fat digestion. In the small intestine, bile salts are almost quantitatively reclaimed and transported back via the portal circulation to the liver. In the liver, hepatocytes take up bile salts and secrete them again into bile for ongoing enterohepatic circulation. Uptake of bile salts into hepatocytes occurs largely in a sodium-dependent manner by the sodium taurocholate cotransporting polypeptide NTCP. The transport properties of NTCP have been extensively characterized. It is an electrogenic member of the solute carrier family of transporters (SLC10A1) and transports predominantly bile salts and sulfated compounds, but is also able to mediate transport of additional substrates, such as thyroid hormones, drugs and toxins. It is highly regulated under physiologic and pathophysiologic conditions. Regulation of NTCP copes with changes of bile salt load to hepatocytes and prevents entry of cytotoxic bile salts during liver disease. Canalicular export of bile salts is mediated by the ATP-binding cassette transporter bile salt export pump BSEP (ABCB11). BSEP constitutes the rate limiting step of hepatocellular bile salt transport and drives enterohepatic circulation of bile salts. It is extensively regulated to keep intracellular bile salt levels low under normal and pathophysiologic situations. Mutations in the BSEP gene lead to severe progressive familial intrahepatic cholestasis. The substrates of BSEP are practically restricted to bile salts and their metabolites. It is, however, subject to inhibition by endogenous metabolites or by drugs. A sustained inhibition will lead to acquired cholestasis, which can end in liver injury.
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Affiliation(s)
- Bruno Stieger
- Division of Clinical Pharmacology and Toxicology, University Hospital, 8091, Zurich, Switzerland.
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