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Hirosawa K, Fujioka H, Morinaga G, Fukami T, Ishiguro N, Kishimoto W, Nakase H, Mizuguchi H, Nakajima M. Quantitative Analysis of mRNA and Protein Expression Levels of Aldo-Keto Reductase and Short-Chain Dehydrogenase/Reductase Isoforms in the Human Intestine. Drug Metab Dispos 2023; 51:1569-1577. [PMID: 37722844 DOI: 10.1124/dmd.123.001402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/31/2023] [Accepted: 09/13/2023] [Indexed: 09/20/2023] Open
Abstract
Enzymes catalyzing the reduction reaction of xenobiotics are mainly members of the aldo-keto reductase (AKR) and short-chain dehydrogenase/reductase (SDR) superfamilies. The intestine, together with the liver, is responsible for first-pass effects and is an organ that determines the bioavailability of orally administered drugs. In this study, we evaluated the mRNA and protein expression levels of 12 AKR isoforms (AKR1A1, AKR1B1, AKR1B10, AKR1B15, AKR1C1, AKR1C2, AKR1C3, AKR1C4, AKR1D1, AKR1E2, AKR7A2, and AKR7A3) and 7 SDR isoforms (CBR1, CBR3, CBR4, DCXR, DHRS4, HSD11B1, and HSD17B12) in each region of the human intestine using next-generation sequencing and data-independent acquisition proteomics. At both the mRNA and protein levels, most AKR isoforms were highly expressed in the upper regions of the intestine, namely the duodenum and jejunum, and then declined toward the rectum. Among the members in the SDR superfamily, CBR1 and DHRS4 were highly expressed in the upper regions, whereas the expression levels of the other isoforms were almost uniform in all regions. Significant positive correlations between mRNA and protein levels were observed in AKR1A1, AKR1B1, AKR1B10, AKR1C3, AKR7A2, AKR7A3, CBR1, and CBR3. The mRNA level of AKR1B10 was highest, followed by AKR7A3 and CBR1, each accounting for more than 10% of the sum of all AKR and SDR levels in the small intestine. This expression profile in the human intestine was greatly different from that in the human liver, where AKR1C isoforms are predominantly expressed. SIGNIFICANCE STATEMENT: In this study comprehensively determined the mRNA and protein expression profiles of aldo-keto reductase (AKR) and short-chain dehydrogenase/reductase isoforms involved in xenobiotic metabolism in the human intestine and found that most of them are highly expressed in the upper region, where AKR1B10, AKR7A3, and CBR1 are predominantly expressed. Since the intestine is significantly involved in the metabolism of orally administered drugs, the information provided here is valuable for pharmacokinetic studies in drug development.
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Affiliation(s)
- Keiya Hirosawa
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences (K.H., T.F., M.N.) and WPI Nano Life Science Institute (T.F., M.N.), Kanazawa University, Kanazawa, Japan; Department of Pharmacokinetics and Nonclinical Safety, Nippon Boehringer Ingelheim Co., Ltd., Kobe, Japan (H.F., G.M., N.I., W.K.); Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, Sapporo, Japan (H.N.); Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan (H.M.); Laboratory of Functional Organoid for Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan (H.M.); Global Center for Medical Engineering and Informatics (H.M.) and Center for Infectious Disease Education and Research (CiDER) (H.M.), Osaka University, Osaka, Japan
| | - Hijiri Fujioka
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences (K.H., T.F., M.N.) and WPI Nano Life Science Institute (T.F., M.N.), Kanazawa University, Kanazawa, Japan; Department of Pharmacokinetics and Nonclinical Safety, Nippon Boehringer Ingelheim Co., Ltd., Kobe, Japan (H.F., G.M., N.I., W.K.); Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, Sapporo, Japan (H.N.); Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan (H.M.); Laboratory of Functional Organoid for Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan (H.M.); Global Center for Medical Engineering and Informatics (H.M.) and Center for Infectious Disease Education and Research (CiDER) (H.M.), Osaka University, Osaka, Japan
| | - Gaku Morinaga
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences (K.H., T.F., M.N.) and WPI Nano Life Science Institute (T.F., M.N.), Kanazawa University, Kanazawa, Japan; Department of Pharmacokinetics and Nonclinical Safety, Nippon Boehringer Ingelheim Co., Ltd., Kobe, Japan (H.F., G.M., N.I., W.K.); Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, Sapporo, Japan (H.N.); Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan (H.M.); Laboratory of Functional Organoid for Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan (H.M.); Global Center for Medical Engineering and Informatics (H.M.) and Center for Infectious Disease Education and Research (CiDER) (H.M.), Osaka University, Osaka, Japan
| | - Tatsuki Fukami
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences (K.H., T.F., M.N.) and WPI Nano Life Science Institute (T.F., M.N.), Kanazawa University, Kanazawa, Japan; Department of Pharmacokinetics and Nonclinical Safety, Nippon Boehringer Ingelheim Co., Ltd., Kobe, Japan (H.F., G.M., N.I., W.K.); Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, Sapporo, Japan (H.N.); Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan (H.M.); Laboratory of Functional Organoid for Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan (H.M.); Global Center for Medical Engineering and Informatics (H.M.) and Center for Infectious Disease Education and Research (CiDER) (H.M.), Osaka University, Osaka, Japan
| | - Naoki Ishiguro
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences (K.H., T.F., M.N.) and WPI Nano Life Science Institute (T.F., M.N.), Kanazawa University, Kanazawa, Japan; Department of Pharmacokinetics and Nonclinical Safety, Nippon Boehringer Ingelheim Co., Ltd., Kobe, Japan (H.F., G.M., N.I., W.K.); Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, Sapporo, Japan (H.N.); Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan (H.M.); Laboratory of Functional Organoid for Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan (H.M.); Global Center for Medical Engineering and Informatics (H.M.) and Center for Infectious Disease Education and Research (CiDER) (H.M.), Osaka University, Osaka, Japan
| | - Wataru Kishimoto
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences (K.H., T.F., M.N.) and WPI Nano Life Science Institute (T.F., M.N.), Kanazawa University, Kanazawa, Japan; Department of Pharmacokinetics and Nonclinical Safety, Nippon Boehringer Ingelheim Co., Ltd., Kobe, Japan (H.F., G.M., N.I., W.K.); Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, Sapporo, Japan (H.N.); Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan (H.M.); Laboratory of Functional Organoid for Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan (H.M.); Global Center for Medical Engineering and Informatics (H.M.) and Center for Infectious Disease Education and Research (CiDER) (H.M.), Osaka University, Osaka, Japan
| | - Hiroshi Nakase
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences (K.H., T.F., M.N.) and WPI Nano Life Science Institute (T.F., M.N.), Kanazawa University, Kanazawa, Japan; Department of Pharmacokinetics and Nonclinical Safety, Nippon Boehringer Ingelheim Co., Ltd., Kobe, Japan (H.F., G.M., N.I., W.K.); Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, Sapporo, Japan (H.N.); Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan (H.M.); Laboratory of Functional Organoid for Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan (H.M.); Global Center for Medical Engineering and Informatics (H.M.) and Center for Infectious Disease Education and Research (CiDER) (H.M.), Osaka University, Osaka, Japan
| | - Hiroyuki Mizuguchi
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences (K.H., T.F., M.N.) and WPI Nano Life Science Institute (T.F., M.N.), Kanazawa University, Kanazawa, Japan; Department of Pharmacokinetics and Nonclinical Safety, Nippon Boehringer Ingelheim Co., Ltd., Kobe, Japan (H.F., G.M., N.I., W.K.); Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, Sapporo, Japan (H.N.); Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan (H.M.); Laboratory of Functional Organoid for Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan (H.M.); Global Center for Medical Engineering and Informatics (H.M.) and Center for Infectious Disease Education and Research (CiDER) (H.M.), Osaka University, Osaka, Japan
| | - Miki Nakajima
- Drug Metabolism and Toxicology, Faculty of Pharmaceutical Sciences (K.H., T.F., M.N.) and WPI Nano Life Science Institute (T.F., M.N.), Kanazawa University, Kanazawa, Japan; Department of Pharmacokinetics and Nonclinical Safety, Nippon Boehringer Ingelheim Co., Ltd., Kobe, Japan (H.F., G.M., N.I., W.K.); Department of Gastroenterology and Hepatology, School of Medicine, Sapporo Medical University, Sapporo, Japan (H.N.); Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan (H.M.); Laboratory of Functional Organoid for Drug Discovery, National Institutes of Biomedical Innovation, Health and Nutrition, Osaka, Japan (H.M.); Global Center for Medical Engineering and Informatics (H.M.) and Center for Infectious Disease Education and Research (CiDER) (H.M.), Osaka University, Osaka, Japan
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Jaćević V, Dumanović J, Alomar SY, Resanović R, Milovanović Z, Nepovimova E, Wu Q, Franca TCC, Wu W, Kuča K. Research update on aflatoxins toxicity, metabolism, distribution, and detection: A concise overview. Toxicology 2023; 492:153549. [PMID: 37209941 DOI: 10.1016/j.tox.2023.153549] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 05/07/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023]
Abstract
Serious health risks associated with the consumption of food products contaminated with aflatoxins (AFs) are worldwide recognized and depend predominantly on consumed AF concentration by diet. A low concentration of aflatoxins in cereals and related food commodities is unavoidable, especially in subtropic and tropic regions. Accordingly, risk assessment guidelines established by regulatory bodies in different countries help in the prevention of aflatoxin intoxication and the protection of public health. By assessing the maximal levels of aflatoxins in food products which are a potential risk to human health, it's possible to establish appropriate risk management strategies. Regarding, a few factors are crucial for making a rational risk management decision, such as toxicological profile, adequate information concerning the exposure duration, availability of routine and some novel analytical techniques, socioeconomic factors, food intake patterns, and maximal allowed levels of each aflatoxin in different food products which may be varied between countries.
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Affiliation(s)
- Vesna Jaćević
- Department for Experimental Pharmacology and Toxicology, National Poison Control Centre, Military Medical Academy, Crnotravska 17, 11000 Belgrade, Serbia; Medical Faculty of the Military Medical Academy, University of Defence, Crnotravska 17, 11000 Belgrade, Serbia; Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanského 62, 500 03 Hradec Králové, Czech Republic.
| | - Jelena Dumanović
- Medical Faculty of the Military Medical Academy, University of Defence, Crnotravska 17, 11000 Belgrade, Serbia; Department of Analytical Chemistry, Faculty of Chemistry, University of Belgrade, 11158 Belgrade, Serbia
| | - Suliman Y Alomar
- King Saud University, College of Science, Zoology Department, Riyadh, 11451, Saudi Arabia
| | - Radmila Resanović
- Faculty of Veterinary Medicine, University of Belgrade, Bulevar Oslobođenja 18, 11000 Belgrade, Serbia
| | - Zoran Milovanović
- Special Police Unit, Ministry of Interior, Trebevićka 12/A, 11 030 Belgrade, Serbia
| | - Eugenie Nepovimova
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanského 62, 500 03 Hradec Králové, Czech Republic
| | - Qinghua Wu
- College of Life Science, Yangtze University, 1 Nanhuan Road, 434023 Jingzhou, Hubei, China; Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanského 62, 500 03 Hradec Králové, Czech Republic
| | - Tanos Celmar Costa Franca
- Laboratory of Molecular Modeling Applied to the Chemical and Biological Defense, Military Institute of Engineering, Praça General Tibúrcio 80, Rio de Janeiro, RJ 22290-270, Brazil; Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanského 62, 500 03 Hradec Králové, Czech Republic
| | - Wenda Wu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanského 62, 500 03 Hradec Králové, Czech Republic
| | - Kamil Kuča
- Biomedical Research Center, University Hospital Hradec Kralove, 50005, Hradec Kralove, Czech Republic; Department of Chemistry, Faculty of Science, University of Hradec Kralove, Rokitanského 62, 500 03 Hradec Králové, Czech Republic
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Wang L, Cao H, Jiang H, Fang Y, Jiang D. A novel 3D bio-printing “liver lobule” microtissue biosensor for the detection of AFB1. Food Res Int 2023; 168:112778. [PMID: 37120227 DOI: 10.1016/j.foodres.2023.112778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 02/14/2023] [Accepted: 03/26/2023] [Indexed: 04/03/2023]
Abstract
In this paper, a novel "liver lobule" microtissue biosensor based on 3D bio-printing is developed to rapidly determine aflatoxin B1 (AFB1). Methylacylated Hyaluronic acid (HAMA) hydrogel, HepG2 cells, and carbon nanotubes are used to construct "liver lobule" models. In addition, 3D bio-printing is used to perform high-throughput and standardized preparation in order to simulate the organ morphology and induce functional formation. Afterwards, based on the electrochemical rapid detection technology, a 3D bio-printed "liver lobule" microtissue is immobilized on the screen-printed electrode, and the mycotoxin is detected by differential pulse voltammetry (DPV). The DPV response increases with the concentration of AFB1 in the range of 0.1-3.5 μg/mL. The linear detection range is 0.1-1.5 μg/mL and the calculated lowest detection limit is 0.039 μg/mL. Thus, this study develops a new mycotoxin detection method based on the 3D printing technology, which has high stability and reproducibility. It has wide application prospects in the field of detection and evaluation of food hazards.
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Affiliation(s)
- Lifeng Wang
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, Nanjing, Jiangsu 210023, PR China
| | - Hanwen Cao
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, Nanjing, Jiangsu 210023, PR China
| | - Hui Jiang
- Key Laboratory of Detection and Traceability Technology of Foodborne Pathogenic Bacteria for Jiangsu Province Market Regulation, Nanjing Institute for Food and Drug Control, Nanjing, Jiangsu 210038, PR China
| | - Yan Fang
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, Nanjing, Jiangsu 210023, PR China
| | - Donglei Jiang
- College of Food Science and Engineering, Collaborative Innovation Center for Modern Grain Circulation and Safety, Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, Nanjing, Jiangsu 210023, PR China.
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Abraham N, Schroeter KL, Zhu Y, Chan J, Evans N, Kimber MS, Carere J, Zhou T, Seah SYK. Structure-function characterization of an aldo-keto reductase involved in detoxification of the mycotoxin, deoxynivalenol. Sci Rep 2022; 12:14737. [PMID: 36042239 PMCID: PMC9427786 DOI: 10.1038/s41598-022-19040-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 08/23/2022] [Indexed: 11/09/2022] Open
Abstract
Deoxynivalenol (DON) is a mycotoxin, produced by filamentous fungi such as Fusarium graminearum, that causes significant yield losses of cereal grain crops worldwide. One of the most promising methods to detoxify this mycotoxin involves its enzymatic epimerization to 3-epi-DON. DepB plays a critical role in this process by reducing 3-keto-DON, an intermediate in the epimerization process, to 3-epi-DON. DepBRleg from Rhizobium leguminosarum is a member of the new aldo-keto reductase family, AKR18, and it has the unusual ability to utilize both NADH and NADPH as coenzymes, albeit with a 40-fold higher catalytic efficiency with NADPH compared to NADH. Structural analysis of DepBRleg revealed the putative roles of Lys-217, Arg-290, and Gln-294 in NADPH specificity. Replacement of these residues by site-specific mutagenesis to negatively charged amino acids compromised NADPH binding with minimal effects on NADH binding. The substrate-binding site of DepBRleg is larger than its closest structural homolog, AKR6A2, likely contributing to its ability to utilize a wide range of aldehydes and ketones, including the mycotoxin, patulin, as substrates. The structure of DepBRleg also suggests that 3-keto-DON can adopt two binding modes to facilitate 4-pro-R hydride transfer to either the re- or si-face of the C3 ketone providing a possible explanation for the enzyme's ability to convert 3-keto-DON to 3-epi-DON and DON in diastereomeric ratios of 67.2% and 32.8% respectively.
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Affiliation(s)
- Nadine Abraham
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada.,Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Kurt L Schroeter
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada
| | - Yan Zhu
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Jonathan Chan
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada.,Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Natasha Evans
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada.,Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Matthew S Kimber
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada
| | - Jason Carere
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Ting Zhou
- Guelph Research and Development Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
| | - Stephen Y K Seah
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada.
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A El-Sadawy A, M G Zedan A, Gamal El-Dein HM. Hepatoprotective Role of Clay and Nano Clay for Alleviating Aflatoxin Toxicity in Male Rats. Pak J Biol Sci 2021; 24:1091-1102. [PMID: 34842380 DOI: 10.3923/pjbs.2021.1091.1102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
<b>Background and Objective:</b> Aflatoxin formed by <i>Aspergillus</i> sp. causes acute hepatotoxicity by DNA damage, gene expression disruption and induced liver carcinoma in humans and laboratory animals. The objectives of this research were to evaluate the protective role of both clay and nano clay as adsorbents to inhibit the side effect of Aflatoxin (AF) by measures the common biological assay of aflatoxicosis in rats along with hepatic gene expression and comet assay. <b>Materials and Methods:</b> Six weeks old male albino rats were distributed into 6 groups with 10 rats per group fed on, Group 1: Basal diet, Group 2: Basal diet with clay (5 g kg<sup></sup><sup>1</sup> diet), Group 3: Basal diet with nano clay (5 g kg<sup></sup><sup>1</sup> diet), Group 4: AF-contaminated diet (1 mg kg<sup></sup><sup>1</sup> diet), Group 5: AF with clay, Group 6: AF with nano clay. <b>Results:</b> AF induced a noticeable increase in the liver function parameters, accompanied by a significant decrease in antioxidant enzyme activities and significant histological alterations in liver tissues. The obtained qPCR results showed a significant up regulation in the expression of Cyp3A6, HO-1, TNFα and NFKB genes in the liver of rats treated with aflatoxin. In contrast, there is a significant down regulation in the expression levels of the Glut2 gene in liver rats treated with aflatoxin. Also, aflatoxin induced a significant increase in DNA damage. Clay and nano clay succeeded in ameliorating the toxic effects of aflatoxin. <b>Conclusion:</b> The results indicated the effective role of clay and nano clay in alleviating aflatoxin and reduce its harmful effects.
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Gützkow KL, Ebmeyer J, Kröncke N, Kampschulte N, Böhmert L, Schöne C, Schebb NH, Benning R, Braeuning A, Maul R. Metabolic fate and toxicity reduction of aflatoxin B1 after uptake by edible Tenebrio molitor larvae. Food Chem Toxicol 2021; 155:112375. [PMID: 34186119 DOI: 10.1016/j.fct.2021.112375] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 10/21/2022]
Abstract
The use of insects as food and feed is gaining more attention for ecological and ethical reasons. Despite the high tolerance of edible yellow mealworm (Tenebrio molitor) larvae to aflatoxin B1 (AFB1), the metabolic fate of the toxin along with its toxic potential in the insect is uncertain. The present study aimed at investigating the AFB1 mass balance and the metabolite formation in a feeding trial with AFB1-contaminated grain flour. T. molitor larvae tolerated the AFB1 level of 10,700 μg/kg in the feed, however, weight gain was decreased by 15% over a 4-weeks feeding period. The investigation of the phase I metabolite pattern revealed the formation of AFM1 and a novel presumably monohydroxylated compound in larvae extracts that was not formed by reference incubation with rat, bovine or porcine liver microsomes. Mass balance quantification of ingested AFB1 revealed that 87% of the initial toxin remain undetected in larval body or residue. Analysis of histone H2Ax phosphorylation in human liver cells as a surrogate for genotoxicity showed that extracts from exposed larvae did not exhibit an elevated toxic potential. Although toxicological uncertainties remain due to the undetected transformation products, the resulting mutagenicity of the edible larvae appears to be low.
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Affiliation(s)
- Kim Lara Gützkow
- German Federal Institute for Risk Assessment (BfR), Department Safety in the Food Chain, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany; Max Rubner-Institute, Federal Research Institute of Nutrition and Food, Department Safety and Quality of Milk and Fish Products (MRI), Hermann-Weigmann-Straße 1, 24103 Kiel, Germany
| | - Johanna Ebmeyer
- German Federal Institute for Risk Assessment (BfR), Department Food Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Nina Kröncke
- University of Applied Sciences Bremerhaven, An der Karlstadt 8, 27568 Bremerhaven, Germany
| | - Nadja Kampschulte
- University of Wuppertal, Faculty of Mathematics and Natural Sciences, Chair of Food Chemistry, Gaußstraße 20, 42119 Wuppertal, Germany
| | - Linda Böhmert
- German Federal Institute for Risk Assessment (BfR), Department Food Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Cindy Schöne
- German Federal Institute for Risk Assessment (BfR), Department Safety in the Food Chain, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Nils Helge Schebb
- University of Wuppertal, Faculty of Mathematics and Natural Sciences, Chair of Food Chemistry, Gaußstraße 20, 42119 Wuppertal, Germany
| | - Rainer Benning
- University of Applied Sciences Bremerhaven, An der Karlstadt 8, 27568 Bremerhaven, Germany
| | - Albert Braeuning
- German Federal Institute for Risk Assessment (BfR), Department Food Safety, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Ronald Maul
- German Federal Institute for Risk Assessment (BfR), Department Safety in the Food Chain, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany; Max Rubner-Institute, Federal Research Institute of Nutrition and Food, Department Safety and Quality of Milk and Fish Products (MRI), Hermann-Weigmann-Straße 1, 24103 Kiel, Germany.
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Inoue A, Ojima T. Functional identification of the 4-deoxy-L-erythro-5-hexoseulose uronate reductase from a brown alga, Saccharina japonica. Biochem Biophys Res Commun 2021; 545:112-118. [PMID: 33548623 DOI: 10.1016/j.bbrc.2021.01.090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 01/25/2021] [Indexed: 11/23/2022]
Abstract
We previously reported the alginate lyase, SjAly, from a brown alga, Saccharina japonica, providing the first experimental evidence for a functional alginate-degradation enzyme in brown algae. 4-deoxy-L-erythro-5-hexoseulose uronate (DEHU), derived from an unsaturated monosaccharide, was identified as the minimum degradation product produced by SjAly-mediated lysis of alginate. DEHU was hitherto reported to be reduced to 2-keto-3-deoxy-gluconate (KDG) by a DEHU-specific reductase with NAD(P)H in alginate-assimilating organisms and its metabolism in alginate-producing organisms is unknown. Here, we report the functional identification of a DEHU reductase, SjRed, in S. japonica. Among the 14 tested compounds, only DEHU was used as a substrate and was converted to KDG in the presence of NADPH. Optimum temperature, pH, and KCl concentration required for SjRed activity were determined to be 25 °C, 7.2, and 100 mM, respectively. SjRed consists of 341 amino acid residues and is proposed to be a member of the aldo-keto reductase superfamily. Sequencing of SjRed revealed that it is composed of at least three exons. These results indicate the existence of an enzyme that reduces DEHU to KDG in S. japonica. This is the first report on the functional identification of a DEHU-reductase in alginate-producing organisms.
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Affiliation(s)
- Akira Inoue
- Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, 041-8611, Japan.
| | - Takao Ojima
- Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, 041-8611, Japan
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Robertson H, Dinkova-Kostova AT, Hayes JD. NRF2 and the Ambiguous Consequences of Its Activation during Initiation and the Subsequent Stages of Tumourigenesis. Cancers (Basel) 2020; 12:E3609. [PMID: 33276631 PMCID: PMC7761610 DOI: 10.3390/cancers12123609] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/19/2020] [Accepted: 11/27/2020] [Indexed: 02/06/2023] Open
Abstract
NF-E2 p45-related factor 2 (NRF2, encoded in the human by NFE2L2) mediates short-term adaptation to thiol-reactive stressors. In normal cells, activation of NRF2 by a thiol-reactive stressor helps prevent, for a limited period of time, the initiation of cancer by chemical carcinogens through induction of genes encoding drug-metabolising enzymes. However, in many tumour types, NRF2 is permanently upregulated. In such cases, its overexpressed target genes support the promotion and progression of cancer by suppressing oxidative stress, because they constitutively increase the capacity to scavenge reactive oxygen species (ROS), and they support cell proliferation by increasing ribonucleotide synthesis, serine biosynthesis and autophagy. Herein, we describe cancer chemoprevention and the discovery of the essential role played by NRF2 in orchestrating protection against chemical carcinogenesis. We similarly describe the discoveries of somatic mutations in NFE2L2 and the gene encoding the principal NRF2 repressor, Kelch-like ECH-associated protein 1 (KEAP1) along with that encoding a component of the E3 ubiquitin-ligase complex Cullin 3 (CUL3), which result in permanent activation of NRF2, and the recognition that such mutations occur frequently in many types of cancer. Notably, mutations in NFE2L2, KEAP1 and CUL3 that cause persistent upregulation of NRF2 often co-exist with mutations that activate KRAS and the PI3K-PKB/Akt pathway, suggesting NRF2 supports growth of tumours in which KRAS or PKB/Akt are hyperactive. Besides somatic mutations, NRF2 activation in human tumours can occur by other means, such as alternative splicing that results in a NRF2 protein which lacks the KEAP1-binding domain or overexpression of other KEAP1-binding partners that compete with NRF2. Lastly, as NRF2 upregulation is associated with resistance to cancer chemotherapy and radiotherapy, we describe strategies that might be employed to suppress growth and overcome drug resistance in tumours with overactive NRF2.
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Affiliation(s)
- Holly Robertson
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK; (H.R.); (A.T.D.-K.)
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Cambridge CB10 1SA, UK
| | - Albena T. Dinkova-Kostova
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK; (H.R.); (A.T.D.-K.)
| | - John D. Hayes
- Jacqui Wood Cancer Centre, Division of Cellular Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK; (H.R.); (A.T.D.-K.)
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Murcia H, Diaz GJ. Dealing with aflatoxin B1 dihydrodiol acute effects: Impact of aflatoxin B1-aldehyde reductase enzyme activity in poultry species tolerant to AFB1 toxic effects. PLoS One 2020; 15:e0235061. [PMID: 32569334 PMCID: PMC7307737 DOI: 10.1371/journal.pone.0235061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 06/07/2020] [Indexed: 11/19/2022] Open
Abstract
Aflatoxin B1 aldehyde reductase (AFAR) enzyme activity has been associated to a higher resistance to the aflatoxin B1 (AFB1) toxicity in ethoxyquin-fed rats. However, no studies about AFAR activity and its relationship with tolerance to AFB1 have been conducted in poultry. To determine the role of AFAR in poultry tolerance, the hepatic in vitro enzymatic activity of AFAR was investigated in liver cytosol from four commercial poultry species (chicken, quail, turkey and duck). Specifically, the kinetic parameters Vmax, Km and intrinsic clearance (CLint) were determined for AFB1 dialdehyde reductase (AFB1-monoalcohol production) and AFB1 monoalcohol reductase (AFB1-dialcohol production). In all cases, AFB1 monoalcohol reductase activity saturated at the highest aflatoxin B1 dialdehyde concentration tested (66.4 μM), whereas AFB1 dialdehyde reductase did not. Both activities were highly and significantly correlated and therefore are most likely catalyzed by the same AFAR enzyme. However, it appears that production of the AFB1 monoalcohol is favored over the AFB1 dialcohol. The production of alcohols from aflatoxin dialdehyde showed the highest enzymatic efficiency (highest CLint value) in chickens, a species resistant to AFB1; however, it was also high in the turkey, a species with intermediate sensitivity; further, CLint values were lowest in another tolerant species (quail) and in the most sensitive poultry species (the duck). These results suggest that AFAR activity is related to resistance to the acute toxic effects of AFB1 only in chickens and ducks. Genetic selection of ducks for high AFAR activity could be a means to control aflatoxin sensitivity in this poultry species.
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Affiliation(s)
- Hansen Murcia
- Laboratorio de Toxicología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional de Colombia, Bogotá D.C., Colombia
| | - Gonzalo J. Diaz
- Laboratorio de Toxicología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional de Colombia, Bogotá D.C., Colombia
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10
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Peles F, Sipos P, Győri Z, Pfliegler WP, Giacometti F, Serraino A, Pagliuca G, Gazzotti T, Pócsi I. Adverse Effects, Transformation and Channeling of Aflatoxins Into Food Raw Materials in Livestock. Front Microbiol 2019; 10:2861. [PMID: 31921041 PMCID: PMC6917664 DOI: 10.3389/fmicb.2019.02861] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 11/26/2019] [Indexed: 01/18/2023] Open
Abstract
Aflatoxins are wide-spread harmful carcinogenic secondary metabolites produced by Aspergillus species, which cause serious feed and food contaminations and affect farm animals deleteriously with acute or chronic manifestations of mycotoxicoses. On farm, both pre-harvest and post-harvest strategies are applied to minimize the risk of aflatoxin contaminations in feeds. The great economic losses attributable to mycotoxin contaminations have initiated a plethora of research projects to develop new, effective technologies to prevent the highly toxic effects of these secondary metabolites on domestic animals and also to block the carry-over of these mycotoxins to humans through the food chain. Among other areas, this review summarizes the latest findings on the effects of silage production technologies and silage microbiota on aflatoxins, and it also discusses the current applications of probiotic organisms and microbial products in feeding technologies. After ingesting contaminated foodstuffs, aflatoxins are metabolized and biotransformed differently in various animals depending on their inherent and acquired physiological properties. These mycotoxins may cause primary aflatoxicoses with versatile, species-specific adverse effects, which are also dependent on the susceptibility of individual animals within a species, and will be a function of the dose and duration of aflatoxin exposures. The transfer of these undesired compounds from contaminated feed into food of animal origin and the aflatoxin residues present in foods become an additional risk to human health, leading to secondary aflatoxicoses. Considering the biological transformation of aflatoxins in livestock, this review summarizes (i) the metabolism of aflatoxins in different animal species, (ii) the deleterious effects of the mycotoxins and their derivatives on the animals, and (iii) the major risks to animal health in terms of the symptoms and consequences of acute or chronic aflatoxicoses, animal welfare and productivity. Furthermore, we traced the transformation and channeling of Aspergillus-derived mycotoxins into food raw materials, particularly in the case of aflatoxin contaminated milk, which represents the major route of human exposure among animal-derived foods. The early and reliable detection of aflatoxins in feed, forage and primary commodities is an increasingly important issue and, therefore, the newly developed, easy-to-use qualitative and quantitative aflatoxin analytical methods are also summarized in the review.
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Affiliation(s)
- Ferenc Peles
- Institute of Food Science, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Debrecen, Hungary
| | - Péter Sipos
- Institute of Nutrition, University of Debrecen, Debrecen, Hungary
| | - Zoltán Győri
- Institute of Nutrition, University of Debrecen, Debrecen, Hungary
| | - Walter P. Pfliegler
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Federica Giacometti
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Andrea Serraino
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Giampiero Pagliuca
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Teresa Gazzotti
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
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11
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Rajib SA, Sharif Siam MK. Characterization and Analysis of Mammalian AKR7A Gene Promoters: Implications for Transcriptional Regulation. Biochem Genet 2019; 58:171-188. [PMID: 31529389 DOI: 10.1007/s10528-019-09936-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 09/03/2019] [Indexed: 01/14/2023]
Abstract
Aldo-keto reductase (AKR) superfamily is responsible for preventing mammalian cells from the toxic and carcinogenic effect of different genotoxic and non-genotoxic chemicals by reducing them, though the inducibility of these genes are different in different species. The aim of this paper is to compare the gene regulation mechanisms of AKR superfamily genes in different species and to identify the conserved areas, which are responsible for gene regulations in the presence of antioxidant, toxicants, and non-genotoxic carcinogens. At the beginning of the analysis AKR genes found in different species were divided into two groups based on their amino acid sequence similarities. Comparison of AKR7A gene clusters between different species revealed that Human AKR7A2 has orthologues in mammalians like rat, mouse, pigs, and other primates. On the other hand, AKR7A3 has orthologues only in rat and AKR7L is present only in primates. All the genes of AKR superfamily have a trend to stay in clusters in mammalian chromosomes having repeated sequences in between them. Transcription start site analysis revealed that genes like human AKR7A2 and rat Akr7a4 do not have conventional promoter regions such as TATA box, CAAT box and have several GC-rich regions, whereas gene like Akr7a1 contains a TATA box 25 bp upstream of transcription start site instead of having CpG islands. Putative orthologous genes i.e., rat AKR7A4, human AKR7A2, and mouse AKR7A5 share more common features such as common transcription factor binding site for specificity protein 1 (SP1), GATA binding factor family, Selenocysteine tRNA gene transcription activating factor (STAF) zinc finger protein, Krüppel-like C2H2 zinc finger (HICF) protein, negative glucocorticoid response element (NGRE) etc. Similarly, genes like rat AKR7A1, human AKR7A3, and human AKR7L share common sequence and transcription factor binding sites. Among those, Nuclear factor erythroid 2-related factor 2 (Nrf2) is thought to be responsible for the inducibility of these genes in the presence of antioxidants. Our analysis revealed that AKR7A gene family consists of genes having a large number of variations in them. Some of these, such as AKR7A2 are housekeeping genes, on the other hand, genes like AKR7A3 are highly inducible in the presence of antioxidants because of the presence of Nrf2 binding site in their promoter. AKR7A1 has a different promoter than others and function of AKR7L gene is still unknown.
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Affiliation(s)
- Samiul Alam Rajib
- Department of Pharmacy, Brac University, 41, Pacific Tower, Mohakhali, Dhaka, 1212, Bangladesh.
| | - Mohammad Kawsar Sharif Siam
- Department of Pharmacy, Brac University, 41, Pacific Tower, Mohakhali, Dhaka, 1212, Bangladesh.,Darwin College, University of Cambridge, Silver Street, Cambridge, CB3 9EU, UK
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12
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Al-Jaal BA, Jaganjac M, Barcaru A, Horvatovich P, Latiff A. Aflatoxin, fumonisin, ochratoxin, zearalenone and deoxynivalenol biomarkers in human biological fluids: A systematic literature review, 2001–2018. Food Chem Toxicol 2019; 129:211-228. [DOI: 10.1016/j.fct.2019.04.047] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 04/11/2019] [Accepted: 04/25/2019] [Indexed: 01/25/2023]
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13
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Rushing BR, Selim MI. Aflatoxin B1: A review on metabolism, toxicity, occurrence in food, occupational exposure, and detoxification methods. Food Chem Toxicol 2019; 124:81-100. [DOI: 10.1016/j.fct.2018.11.047] [Citation(s) in RCA: 325] [Impact Index Per Article: 65.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 11/16/2018] [Accepted: 11/19/2018] [Indexed: 12/30/2022]
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14
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Pate RT, Cardoso FC. Injectable trace minerals (selenium, copper, zinc, and manganese) alleviate inflammation and oxidative stress during an aflatoxin challenge in lactating multiparous Holstein cows. J Dairy Sci 2018; 101:8532-8543. [PMID: 29935830 DOI: 10.3168/jds.2018-14447] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 05/03/2018] [Indexed: 12/13/2022]
Abstract
Trace minerals are vital in the antioxidant response during oxidative stress; however, limited research is available on the effects of trace mineral supplementation during an aflatoxin (AF) challenge. The objective of the study was to determine the effects of 2 subcutaneous injections of 15 mg/mL of Cu, 5 mg/mL of Se, 60 mg/mL of Zn, and 10 mg/mL of Mn (Multimin 90, Multimin North America, Fort Collins, CO) given at 1 mL/90.7 kg of average body weight in response to an AF challenge. Fifty-eight Holstein cows [body weight (mean ± SD) = 734 ± 6 0kg; days in milk = 191 ± 93] were assigned to 1 of 3 treatments in a randomized complete block design. The experimental period (63 d) was divided into an adaptation phase (d 1-56) and a measurement phase (d 57-63). From d 57 to 59, cows received an AF challenge that consisted of 100 μg of aflatoxin B1/kg of dietary dry matter intake (DMI) administered orally via balling gun. Treatments were saline injection and no AF challenge (NEG), saline injection and AF challenge (POS), and trace mineral injection and AF challenge (MM). Injections were performed subcutaneously on d 1 and 29. Milk was sampled 3 times daily from d 56 to 63, blood was sampled on d 0, 56, 60, and 63, and liver samples were taken on d 0 and 60. Two treatment orthogonal contrasts [CONT1 (NEG vs. POS) and CONT2 (POS vs. MM)] were made. Cows in NEG had lower AF excretion in milk and greater 3.5% fat-corrected milk (32.1 ± 1.37 kg/d) compared with cows in POS (28.6 ± 1.43 kg/d). Feed efficiencies (3.5% fat-corrected milk/DMI, energy-corrected milk/DMI, and milk/DMI) were greater for cows in NEG (1.42 ± 0.07, 1.46 ± 0.07, and 1.45 ± 0.07, respectively) than cows in POS (1.16 ± 0.08, 1.18 ± 0.08, and 1.22 ± 0.07, respectively). Cows in POS had greater milk urea nitrogen and blood urea nitrogen than cows in MM. Liver concentrations of Se and Fe were greater for cows in MM compared with cows in POS. Cows in MM tended to have greater plasma glutathione peroxidase activity compared with cows in POS. An upregulation of liver GPX1 was observed for cows in POS compared with cows in MM. In conclusion, subcutaneous injection of trace minerals maintained an adequate antioxidant response when an AF challenge was present.
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Affiliation(s)
- R T Pate
- Department of Animal Sciences, University of Illinois, Urbana 61801
| | - F C Cardoso
- Department of Animal Sciences, University of Illinois, Urbana 61801.
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15
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Smith LE, Prendergast AJ, Turner PC, Humphrey JH, Stoltzfus RJ. Aflatoxin Exposure During Pregnancy, Maternal Anemia, and Adverse Birth Outcomes. Am J Trop Med Hyg 2017; 96:770-776. [PMID: 28500823 PMCID: PMC5392618 DOI: 10.4269/ajtmh.16-0730] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Pregnant women and their developing fetuses are vulnerable to multiple environmental insults, including exposure to aflatoxin, a mycotoxin that may contaminate as much as 25% of the world food supply. We reviewed and integrated findings from studies of aflatoxin exposure during pregnancy and evaluated potential links to adverse pregnancy outcomes. We identified 27 studies (10 human cross-sectional studies and 17 animal studies) assessing the relationship between aflatoxin exposure and adverse birth outcomes or anemia. Findings suggest that aflatoxin exposure during pregnancy may impair fetal growth. Only one human study investigated aflatoxin exposure and prematurity, and no studies investigated its relationship with pregnancy loss, but animal studies suggest aflatoxin exposure may increase risk for prematurity and pregnancy loss. The fetus could be affected by maternal aflatoxin exposure through direct toxicity as well as indirect toxicity, via maternal systemic inflammation, impaired placental growth, or elevation of placental cytokines. The cytotoxic and systemic effects of aflatoxin could plausibly mediate maternal anemia, intrauterine growth restriction, fetal loss, and preterm birth. Given the widespread exposure to this toxin in developing countries, longitudinal studies in pregnant women are needed to provide stronger evidence for the role of aflatoxin in adverse pregnancy outcomes, and to explore biological mechanisms. Potential pathways for intervention to reduce aflatoxin exposure are urgently needed, and this might reduce the global burden of stillbirth, preterm birth, and low birthweight.
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Affiliation(s)
- Laura E Smith
- Division of Nutritional Sciences, Cornell University, Ithaca, New York.,Zvitambo Institute for Maternal and Child Health Research, Harare, Zimbabwe
| | - Andrew J Prendergast
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,Blizard Institute, Queen Mary University of London, London, United Kingdom.,Zvitambo Institute for Maternal and Child Health Research, Harare, Zimbabwe
| | - Paul C Turner
- Maryland Institute for Applied Environmental Health, School of Public Health, University of Maryland, College Park, Maryland
| | - Jean H Humphrey
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,Blizard Institute, Queen Mary University of London, London, United Kingdom
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16
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Manzini L, Halwachs S, Girolami F, Badino P, Honscha W, Nebbia C. Interaction of mammary bovine ABCG2 with AFB1 and its metabolites and regulation by PCB 126 in a MDCKII in vitro model. J Vet Pharmacol Ther 2017; 40:591-598. [PMID: 28198024 DOI: 10.1111/jvp.12397] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 12/23/2016] [Indexed: 12/27/2022]
Abstract
The ATP-binding cassette efflux transporter ABCG2 plays a key role in the mammary excretion of drugs and toxins in humans and animals. Aflatoxins (AF) are worldwide contaminants of food and feed commodities, while PCB 126 is a dioxin-like PCB which may contaminate milk and dairy products. Both compounds are known human carcinogens. The interactions between AF and bovine ABCG2 (bABCG2) as well as the effects of PCB 126 on its efflux activity have been investigated by means of the Hoechst H33342 transport assay in MDCKII cells stably expressing mammary bABCG2. Both AFB1 and its main milk metabolite AFM1 showed interaction with bABCG2 even at concentrations approaching the legal limits in feed and food commodities. Moreover, PCB 126 significantly enhanced bABCG2 functional activity. Specific inhibitors of either AhR (CH233191) or ABCG2 (Ko143) were able to reverse the PCB 126-induced increase in bABCG2 transport activity, showing the specific upregulation of the efflux protein by the AhR pathway. The incubation of PCB 126-pretreated cells with AFM1 was able to substantially reverse such effect, with still unknown mechanism(s). Overall, results from this study point to AFB1 and AFM1 as likely bABCG2 substrates. The PCB 126-dependent increased activity of the transporter could enhance the ABCG2-mediated excretion into dairy milk of chemicals (i.e., drugs and toxins) potentially harmful to neonates and consumers.
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Affiliation(s)
- L Manzini
- Department of Veterinary Sciences, University of Torino, Grugliasco, Italy
| | - S Halwachs
- Institute of Veterinary Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - F Girolami
- Department of Veterinary Sciences, University of Torino, Grugliasco, Italy
| | - P Badino
- Department of Veterinary Sciences, University of Torino, Grugliasco, Italy
| | - W Honscha
- Institute of Veterinary Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - C Nebbia
- Department of Veterinary Sciences, University of Torino, Grugliasco, Italy
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Abstract
The biochemical facets of toxicology have always had a major role in providing insight into mechanisms. Some of the history of the development of this area is summarized, including metabolism, enzymology, and the chemistry of reactive intermediates. Knowledge in these fields has had a major impact in the areas of drug metabolism and safety assessment, which are both critical steps in the development of pharmaceuticals and the rational use of commodity chemicals. The science of toxicology has developed considerably with input from other disciplines and today is poised to emerge as a predictive science with even more dramatic impact. The challenges ahead are considerable but there is renewed excitement in the potential of the field. As in the past, further advances in the field of toxicology will require the input of knowledge from many disciplines.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
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18
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Monson MS, Cardona CJ, Coulombe RA, Reed KM. Hepatic Transcriptome Responses of Domesticated and Wild Turkey Embryos to Aflatoxin B₁. Toxins (Basel) 2016; 8:toxins8010016. [PMID: 26751476 PMCID: PMC4728538 DOI: 10.3390/toxins8010016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 12/23/2015] [Accepted: 12/30/2015] [Indexed: 11/16/2022] Open
Abstract
The mycotoxin, aflatoxin B₁ (AFB₁) is a hepatotoxic, immunotoxic, and mutagenic contaminant of food and animal feeds. In poultry, AFB₁ can be maternally transferred to embryonated eggs, affecting development, viability and performance after hatch. Domesticated turkeys (Meleagris gallopavo) are especially sensitive to aflatoxicosis, while Eastern wild turkeys (M. g. silvestris) are likely more resistant. In ovo exposure provided a controlled AFB₁ challenge and comparison of domesticated and wild turkeys. Gene expression responses to AFB₁ in the embryonic hepatic transcriptome were examined using RNA-sequencing (RNA-seq). Eggs were injected with AFB₁ (1 μg) or sham control and dissected for liver tissue after 1 day or 5 days of exposure. Libraries from domesticated turkey (n = 24) and wild turkey (n = 15) produced 89.2 Gb of sequence. Approximately 670 M reads were mapped to a turkey gene set. Differential expression analysis identified 1535 significant genes with |log₂ fold change| ≥ 1.0 in at least one pair-wise comparison. AFB₁ effects were dependent on exposure time and turkey type, occurred more rapidly in domesticated turkeys, and led to notable up-regulation in cell cycle regulators, NRF2-mediated response genes and coagulation factors. Further investigation of NRF2-response genes may identify targets to improve poultry resistance.
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Affiliation(s)
- Melissa S Monson
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USA.
| | - Carol J Cardona
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USA.
| | - Roger A Coulombe
- Department of Animal, Dairy and Veterinary Sciences, College of Agriculture, Utah State University, Logan, UT 84322, USA.
| | - Kent M Reed
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USA.
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Abdel-Wahhab MA, Aljawish A, El-Nekeety AA, Abdel-Aiezm SH, Abdel-Kader HAM, Rihn BH, Joubert O. Chitosan nanoparticles and quercetin modulate gene expression and prevent the genotoxicity of aflatoxin B 1 in rat liver. Toxicol Rep 2015; 2:737-747. [PMID: 28962409 PMCID: PMC5598511 DOI: 10.1016/j.toxrep.2015.05.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/01/2015] [Accepted: 05/04/2015] [Indexed: 11/30/2022] Open
Abstract
The aims of the current study were to prepare chitosan nanoparticles (CNPs) and to evaluate its protective role alone or in combination with quercetin (Q) against AFB1-induce cytotoxicity in rats. Male Sprague-Dawley rats were divided into 12 groups and treated orally for 4 weeks as follow: the control group, the group treated with AFB1 (80 μg/kg b.w.) in corn oil, the groups treated with low (140 mg/kg b.w.) or high (280 mg/kg b.w.) dose of CNPs, the group treated with Q (50 mg/kg b.w.), the groups treated with Q plus the low or the high dose of CNPs and the groups treated with AFB1 plus Q and/or CNPs at the two tested doses. The results also revealed that administration of AFB1 resulted in a significant increase in serum cytokines, Procollagen III, Nitric Oxide, lipid peroxidation and DNA fragmentation accompanied with a significant decrease in GPx I and Cu–Zn SOD-mRNA gene expression. Q and/or CNPs at the two tested doses overcome these effects especially in the group treated with the high dose of CNPs plus Q. It could be concluded that CNPs is a promise candidate as drug delivery enhances the protective effect of Q against the cytogenetic effects of AFB1 in high endemic areas.
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Affiliation(s)
- Mosaad A Abdel-Wahhab
- Food Toxicology & Contaminants Department, National Research Center, Dokki, Cairo, Egypt
| | - Abdulhadi Aljawish
- Université de Lorraine, Laboratoire d'Ingénierie des Biomolécules (LIBio), 2 avenue de la Forêt de Haye, TSA40602-F-54518 Vandœuvre-lès-Nancy, France
| | - Aziza A El-Nekeety
- Food Toxicology & Contaminants Department, National Research Center, Dokki, Cairo, Egypt
| | | | | | - Bertrand H Rihn
- Faculty of Pharmacy, EA 3452 CITHEFOR, Lorraine University, 54001 Nancy Cedex, France
| | - Olivier Joubert
- Faculty of Pharmacy, EA 3452 CITHEFOR, Lorraine University, 54001 Nancy Cedex, France
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20
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Weber S, Salabei JK, Möller G, Kremmer E, Bhatnagar A, Adamski J, Barski OA. Aldo-keto Reductase 1B15 (AKR1B15): a mitochondrial human aldo-keto reductase with activity toward steroids and 3-keto-acyl-CoA conjugates. J Biol Chem 2015; 290:6531-45. [PMID: 25577493 DOI: 10.1074/jbc.m114.610121] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Aldo-keto reductases (AKRs) comprise a superfamily of proteins involved in the reduction and oxidation of biogenic and xenobiotic carbonyls. In humans, at least 15 AKR superfamily members have been identified so far. One of these is a newly identified gene locus, AKR1B15, which clusters on chromosome 7 with the other human AKR1B subfamily members (i.e. AKR1B1 and AKR1B10). We show that alternative splicing of the AKR1B15 gene transcript gives rise to two protein isoforms with different N termini: AKR1B15.1 is a 316-amino acid protein with 91% amino acid identity to AKR1B10; AKR1B15.2 has a prolonged N terminus and consists of 344 amino acid residues. The two gene products differ in their expression level, subcellular localization, and activity. In contrast with other AKR enzymes, which are mostly cytosolic, AKR1B15.1 co-localizes with the mitochondria. Kinetic studies show that AKR1B15.1 is predominantly a reductive enzyme that catalyzes the reduction of androgens and estrogens with high positional selectivity (17β-hydroxysteroid dehydrogenase activity) as well as 3-keto-acyl-CoA conjugates and exhibits strong cofactor selectivity toward NADP(H). In accordance with its substrate spectrum, the enzyme is expressed at the highest levels in steroid-sensitive tissues, namely placenta, testis, and adipose tissue. Placental and adipose expression could be reproduced in the BeWo and SGBS cell lines, respectively. In contrast, AKR1B15.2 localizes to the cytosol and displays no enzymatic activity with the substrates tested. Collectively, these results demonstrate the existence of a novel catalytically active AKR, which is associated with mitochondria and expressed mainly in steroid-sensitive tissues.
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Affiliation(s)
- Susanne Weber
- From the Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Institute of Experimental Genetics, Genome Analysis Center, 85764 Neuherberg, Germany
| | - Joshua K Salabei
- the Diabetes and Obesity Center, School of Medicine, University of Louisville, Louisville, Kentucky 40202
| | - Gabriele Möller
- From the Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Institute of Experimental Genetics, Genome Analysis Center, 85764 Neuherberg, Germany
| | - Elisabeth Kremmer
- the Institute of Molecular Immunology, German Research Center for Environmental Health, Helmholtz Zentrum Muenchen, 81377 Muenchen, Germany
| | - Aruni Bhatnagar
- the Diabetes and Obesity Center, School of Medicine, University of Louisville, Louisville, Kentucky 40202
| | - Jerzy Adamski
- From the Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Institute of Experimental Genetics, Genome Analysis Center, 85764 Neuherberg, Germany, the Lehrstuhl für Experimentelle Genetik, Technische Universitaet Muenchen, 85356 Freising-Weihenstephan, Germany, and the German Center for Diabetes Research, 85764 Neuherberg, Germany
| | - Oleg A Barski
- the Diabetes and Obesity Center, School of Medicine, University of Louisville, Louisville, Kentucky 40202,
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Mary VS, Valdehita A, Navas JM, Rubinstein HR, Fernández-Cruz ML. Effects of aflatoxin B1, fumonisin B1 and their mixture on the aryl hydrocarbon receptor and cytochrome P450 1A induction. Food Chem Toxicol 2015; 75:104-11. [DOI: 10.1016/j.fct.2014.10.030] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/22/2014] [Accepted: 10/25/2014] [Indexed: 11/30/2022]
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Trp266 determines the binding specificity of a porcine aflatoxin B₁ aldehyde reductase for aflatoxin B₁-dialdehyde. Biochem Pharmacol 2013; 86:1357-65. [PMID: 24008121 DOI: 10.1016/j.bcp.2013.08.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/10/2013] [Accepted: 08/12/2013] [Indexed: 11/23/2022]
Abstract
Aflatoxin B₁ (AFB₁) is a severe threat to human and animal health. The aflatoxin B₁ aldehyde reductase (AFAR) family specifically catalyzes AFB₁-dialdehyde, a toxic metabolic intermediate of AFB₁, producing a nontoxic dialcohol. Although several AFARs have been found and characterized, the binding specificity of the family for AFB₁-dialdehyde remains unclear. Herein, according to the published sequence, we cloned a porcine AFAR gene. Recombinant porcine AFAR was expressed and purified from Escherichia coli as hexa-histidine tagged fusion protein. Using the cloned porcine AFAR as a model, site-directed mutagenesis combined with high performance liquid chromatography studies revealed that the substitution of Trp266 with Ala resulted in almost complete loss of catalytic activity for AFB₁-dialdehyde. Interestingly, the substitution of Met86 with Ala exhibited an obviously increased activity to the dialdehyde. Based on these results and by using molecular docking simulations, this work provides a structural explanation for why the AFAR family exhibits high specificity for AFB₁-dialdehyde. The Trp266 residue in porcine AFAR plays a critical role in stabilizing the binding of AFB₁-dialdehyde in the active pocket through the hydrophobic interaction of the side-chain indole ring of Trp266 with the fused coumarin rings of the dialdehyde molecule. The enhanced activity of M86A may be attributed to the formed π-π stacking interaction between Trp266 and the dialdehyde. In addition, other hydrophobic residues (e.g. Phe and Trp) around the dialdehyde molecule also stabilize the substrate binding. The findings may contribute to understanding the substrate specificity of the AFAR family for AFB₁-dialdehyde.
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Potential Antioxidant Role of Tridham in Managing Oxidative Stress against Aflatoxin-B(1)-Induced Experimental Hepatocellular Carcinoma. Int J Hepatol 2012; 2012:428373. [PMID: 22518320 PMCID: PMC3296305 DOI: 10.1155/2012/428373] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 09/23/2011] [Accepted: 10/16/2011] [Indexed: 11/17/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is one of the most fatal cancers due to delayed diagnosis and lack of effective treatment options. Significant exposure to Aflatoxin B(1) (AFB(1)), a potent hepatotoxic and hepatocarcinogenic mycotoxin, plays a major role in liver carcinogenesis through oxidative tissue damage and p53 mutation. The present study emphasizes the anticarcinogenic effect of Tridham (TD), a polyherbal traditional medicine, on AFB(1)-induced HCC in male Wistar rats. AFB(1)-administered HCC-bearing rats (Group II) showed increased levels of lipid peroxides (LPOs), thiobarbituric acid substances (TBARs), and protein carbonyls (PCOs) and decreased levels of enzymic and nonenzymic antioxidants when compared to control animals (Group I). Administration of TD orally (300 mg/kg body weight/day) for 45 days to HCC-bearing animals (Group III) significantly reduced the tissue damage accompanied by restoration of the levels of antioxidants. Histological observation confirmed the induction of tumour in Group II animals and complete regression of tumour in Group III animals. This study highlights the potent antioxidant properties of TD which contribute to its therapeutic effect in AFB(1)-induced HCC in rats.
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Škarydová L, Wsól V. Human microsomal carbonyl reducing enzymes in the metabolism of xenobiotics: well-known and promising members of the SDR superfamily. Drug Metab Rev 2011; 44:173-91. [DOI: 10.3109/03602532.2011.638304] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Ahmed MME, Wang T, Luo Y, Ye S, Wu Q, Guo Z, Roebuck BD, Sutter TR, Yang JY. Aldo-keto reductase-7A protects liver cells and tissues from acetaminophen-induced oxidative stress and hepatotoxicity. Hepatology 2011; 54:1322-32. [PMID: 21688283 DOI: 10.1002/hep.24493] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 06/01/2011] [Indexed: 12/11/2022]
Abstract
UNLABELLED Aldo-keto reductase-7A (AKR7A) is an enzyme important for bioactivation and biodetoxification. Previous studies suggested that Akr7a might be transcriptionally regulated by oxidative stress-responsive transcription factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2), a protein highly responsive to acetaminophen (APAP) or its intermediate metabolite, N-acetyl-p-benzoquinoneimine (NAPQI). This study was, therefore, carried out to investigate whether Akr7a is involved in the protection against APAP-induced oxidative stress and hepatotoxicity. We found that in response to APAP or NAPQI exposure, Akr7a3 mRNA and protein were significantly up-regulated in vitro in human HepG2 and LO2 cells. Similarly, strong induction was observed for Akr7a5 in mouse AML12 hepatocytes exposed to APAP. In vivo in wild-type rats, significant up-regulation of hepatic AKR7A1 protein was observed after administration of APAP. On the other hand, depletion of Nrf2 reduced the expression of Akr7a3, suggesting that Nrf2, indeed, contributes significantly to the induction of Akr7a. Moreover, loss of cell viability in Nrf2-depleted cells was significantly rescued by coexpression of AKR7A3. Furthermore, increased AKR7A3 in HepG2 cells was associated with the up-regulation of oxidative stress-related enzymes to enhance cellular antioxidant defense, which appeared to contribute significantly to protection against APAP-induced toxicity. In a line of transgenic rats overexpressing AKR7A1, increased AKR7A1 stimulated the expression of Nrf2 and other Nrf2-regulated genes, but did not better protect rats from APAP insults. In contrast, depletion of Akr7a5 in vitro in cultured AML12 cells or depletion of Akr7a1 in vivo in rat liver greatly increased APAP-induced hepatotoxicity. CONCLUSION AKR7A proteins are significantly up-regulated in response to APAP/NAPQI exposure to contribute significantly to protection against APAP-induced hepatotoxicity. AKR7A mediates this protection, in part, through enhancing hepatocellular antioxidant defense.
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Affiliation(s)
- Munzir M E Ahmed
- State Key Laboratory of Stress Cell Biology and Department of Biomedical Sciences, School of Life Sciences, Xiamen University, Xiamen, China
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Hayes JD, McMahon M, Chowdhry S, Dinkova-Kostova AT. Cancer chemoprevention mechanisms mediated through the Keap1-Nrf2 pathway. Antioxid Redox Signal 2010; 13:1713-48. [PMID: 20446772 DOI: 10.1089/ars.2010.3221] [Citation(s) in RCA: 412] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The cap'n'collar (CNC) bZIP transcription factor Nrf2 controls expression of genes for antioxidant enzymes, metal-binding proteins, drug-metabolising enzymes, drug transporters, and molecular chaperones. Many chemicals that protect against carcinogenesis induce Nrf2-target genes. These compounds are all thiol-reactive and stimulate an adaptive response to redox stress in cells. Such agents induce the expression of genes that posses an antioxidant response element (ARE) in their regulatory regions. Under normal homeostatic conditions, Nrf2 activity is restricted through a Keap1-dependent ubiquitylation by Cul3-Rbx1, which targets the CNC-bZIP transcription factor for proteasomal degradation. However, as the substrate adaptor function of Keap1 is redox-sensitive, Nrf2 protein evades ubiquitylation by Cul3-Rbx1 when cells are treated with chemopreventive agents. As a consequence, Nrf2 accumulates in the nucleus where it heterodimerizes with small Maf proteins and transactivates genes regulated through an ARE. In this review, we describe synthetic compounds and phytochemicals from edible plants that induce Nrf2-target genes. We also discuss evidence for the existence of different classes of ARE (a 16-bp 5'-TMAnnRTGABnnnGCR-3' versus an 11-bp 5'-RTGABnnnGCR-3', with or without the embedded activator protein 1-binding site 5'-TGASTCA-3'), species differences in the ARE-gene battery, and the identity of critical Cys residues in Keap1 required for de-repression of Nrf2 by chemopreventive agents.
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Affiliation(s)
- John D Hayes
- Biomedical Research Institute, Ninewells Hospital, University of Dundee, Scotland, United Kingdom.
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Tran QT, Xu L, Phan V, Goodwin SB, Rahman M, Jin VX, Sutter CH, Roebuck BD, Kensler TW, George E, Sutter TR. Chemical genomics of cancer chemopreventive dithiolethiones. Carcinogenesis 2009; 30:480-6. [PMID: 19126641 PMCID: PMC2650797 DOI: 10.1093/carcin/bgn292] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 12/17/2008] [Accepted: 12/20/2008] [Indexed: 01/20/2023] Open
Abstract
3H-1,2-dithiole-3-thione (D3T) and its analogues 4-methyl-5-pyrazinyl-3H-1,2-dithiole-3-thione (OLT) and 5-tert-butyl-3H-1,2-dithiole-3-thione (TBD) are chemopreventive agents that block or diminish early stages of carcinogenesis by inducing activities of detoxication enzymes. While OLT has been used in clinical trials, TBD has been shown to be more efficacious and possibly less toxic than OLT in animals. Here, we utilize a robust and high-resolution chemical genomics procedure to examine the pharmacological structure-activity relationships of these compounds in livers of male rats by microarray analyses. We identified 226 differentially expressed genes that were common to all treatments. Functional analysis identified the relation of these genes to glutathione metabolism and the nuclear factor, erythroid derived 2-related factor 2 pathway (Nrf2) that is known to regulate many of the protective actions of dithiolethiones. OLT and TBD were shown to have similar efficacies and both were weaker than D3T. In addition, we identified 40 genes whose responses were common to OLT and TBD, yet distinct from D3T. As inhibition of cytochrome P450 (CYP) has been associated with the effects of OLT on CYP expression, we determined the half maximal inhibitory concentration (IC(50)) values for inhibition of CYP1A2. The rank order of inhibitor potency was OLT >> TBD >> D3T, with IC(50) values estimated as 0.2, 12.8 and >100 microM, respectively. Functional analysis revealed that OLT and TBD, in addition to their effects on CYP, modulate liver lipid metabolism, especially fatty acids. Together, these findings provide new insight into the actions of clinically relevant and lead dithiolethione analogues.
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Affiliation(s)
- Quynh T. Tran
- Department of Mathematical Sciences
- Department of Biology, University of Memphis, Memphis, TN 38152, USA
- W. Harry Feinstone Center for Genomic Research
| | - Lijing Xu
- Department of Mathematical Sciences
- W. Harry Feinstone Center for Genomic Research
| | - Vinhthuy Phan
- W. Harry Feinstone Center for Genomic Research
- Department of Computer Science, University of Memphis, Memphis, TN 38152, USA
| | - Shirlean B. Goodwin
- Department of Biology, University of Memphis, Memphis, TN 38152, USA
- W. Harry Feinstone Center for Genomic Research
| | - Mostafizur Rahman
- Department of Biology, University of Memphis, Memphis, TN 38152, USA
- W. Harry Feinstone Center for Genomic Research
| | - Victor X. Jin
- Department of Biology, University of Memphis, Memphis, TN 38152, USA
| | - Carrie H. Sutter
- Department of Biology, University of Memphis, Memphis, TN 38152, USA
- W. Harry Feinstone Center for Genomic Research
| | - Bill D. Roebuck
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, NH 03755, USA
| | - Thomas W. Kensler
- Department of Environmental Health Sciences, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - E.Olusegun George
- Department of Mathematical Sciences
- W. Harry Feinstone Center for Genomic Research
- Department of Computer Science, University of Memphis, Memphis, TN 38152, USA
| | - Thomas R. Sutter
- Department of Biology, University of Memphis, Memphis, TN 38152, USA
- W. Harry Feinstone Center for Genomic Research
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Roebuck BD, Johnson DN, Sutter CH, Egner PA, Scholl PF, Friesen MD, Baumgartner KJ, Ware NM, Bodreddigari S, Groopman JD, Kensler TW, Sutter TR. Transgenic expression of aflatoxin aldehyde reductase (AKR7A1) modulates aflatoxin B1 metabolism but not hepatic carcinogenesis in the rat. Toxicol Sci 2009; 109:41-9. [PMID: 19168568 DOI: 10.1093/toxsci/kfp003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In both experimental animals and humans, aflatoxin B(1) (AFB(1)) is a potent hepatic toxin and carcinogen against which a variety of antioxidants and experimental or therapeutic drugs (e.g., oltipraz, related dithiolethiones, and various triterpenoids) protect from both acute toxicity and carcinogenesis. These agents induce several hepatic glutathione S-transferases (GST) as well as aldo-keto reductases (AKR) which are thought to contribute to protection. Studies were undertaken in transgenic rats to examine the role of one inducible enzyme, AKR7A1, for protection against acute and chronic actions of AFB(1) by enhancing detoxication of a reactive metabolite, AFB(1) dialdehyde, by reduction to alcohols. The AFB(1) dialdehyde forms adducts with protein amino groups by a Schiff base mechanism and these adducts have been theorized to be at least one cause of the acute toxicity of AFB(1) and to enhance carcinogenesis. A liver-specific AKR7A1 transgenic rat was constructed in the Sprague-Dawley strain and two lines, AKR7A1(Tg2) and AKR7A1(Tg5), were found to overexpress AKR7A1 by 18- and 8-fold, respectively. Rates of formation of AFB(1) alcohols, both in hepatic cytosols and as urinary excretion products, increased in the transgenic lines with AKR7A1(Tg2) being the highest. Neither line offered protection against acute AFB(1)-induced bile duct proliferation, a functional assessment of acute hepatotoxicity by AFB(1), nor did they protect against the formation of GST-P positive putative preneoplastic foci as a result of chronic exposure to AFB(1). These results imply that the prevention of protein adducts mediated by AKR are not critical to protection against AFB(1) tumorigenicity.
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Affiliation(s)
- Bill D Roebuck
- Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, USA
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Bodreddigari S, Jones LK, Egner PA, Groopman JD, Sutter CH, Roebuck BD, Guengerich FP, Kensler TW, Sutter TR. Protection against aflatoxin B1-induced cytotoxicity by expression of the cloned aflatoxin B1-aldehyde reductases rat AKR7A1 and human AKR7A3. Chem Res Toxicol 2008; 21:1134-42. [PMID: 18416522 DOI: 10.1021/tx7004458] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The reduction of the aflatoxin B 1 (AFB 1) dialdehyde metabolite to its corresponding mono and dialcohols, catalyzed by aflatoxin B 1-aldehyde reductase (AFAR, rat AKR7A1, and human AKR7A3), is greatly increased in livers of rats treated with numerous chemoprotective agents. Recombinant human AKR7A3 has been shown to reduce the AFB 1-dialdehyde at rates greater than those of the rat AKR7A1. The activity of AKR7A1 or AKR7A3 may detoxify the AFB 1-dialdehyde, which reacts with proteins, and thereby inhibits AFB 1-induced toxicity; however, direct experimental evidence of this hypothesis was lacking. Two human B lymphoblastoid cell lines, designated pMF6/1A2/AKR7A1 and pMF6/1A2, were genetically engineered to stably express AKR7A1 and/or cytochrome P4501A2 (1A2). The pMF6/1A2/AKR7A1 cells were refractory to the cytotoxic effects of 3 ng/mL AFB 1, in comparison to pM6/1A2 cells, which were more sensitive. Diminished protection occurred at higher concentrations of AFB 1 in pMF6/1A2/AKR7A1 cells, suggesting that additional factors were influencing cell survival. COS-7 cells were transfected with either vector control, rat AKR7A1, or human AKR7A3, and the cells were treated with AFB 1-dialdehyde. There was a 6-fold increase in the dialdehyde LC 50, from 66 microM in vector-transfected cells to 400 microM in AKR7A1-transfected cells, and an 8.5-fold increase from 35 microM in vector-transfected cells to 300 microM in AKR7A3-transfected cells. In both cases, this protective effect of the AFAR enzyme was accompanied by a marked decrease in protein adducts. Fractionation of the cellular protein showed that the mitochondria/nuclei and microsomal fractions contained the highest concentration of protein adducts. The levels of human AKR7A3 and AKR7A2 were measured in 12 human liver samples. The expression of AKR7A3 was detectable in all livers and lower than those of AKR7A2 in 11 of the 12 samples. Overall, these results provide the first direct evidence of a role for rat AKR7A1 and human AKR7A3 in protection against AFB 1-induced cytotoxicity and protein adduct formation.
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Affiliation(s)
- Sridevi Bodreddigari
- Department of Biology and W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee 38152, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt School of Medicine, Nashville, Tennessee 37232
| | - Laundette Knight Jones
- Department of Biology and W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee 38152, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt School of Medicine, Nashville, Tennessee 37232
| | - Patricia A Egner
- Department of Biology and W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee 38152, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt School of Medicine, Nashville, Tennessee 37232
| | - John D Groopman
- Department of Biology and W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee 38152, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt School of Medicine, Nashville, Tennessee 37232
| | - Carrie Hayes Sutter
- Department of Biology and W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee 38152, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt School of Medicine, Nashville, Tennessee 37232
| | - Bill D Roebuck
- Department of Biology and W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee 38152, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt School of Medicine, Nashville, Tennessee 37232
| | - F Peter Guengerich
- Department of Biology and W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee 38152, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt School of Medicine, Nashville, Tennessee 37232
| | - Thomas W Kensler
- Department of Biology and W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee 38152, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt School of Medicine, Nashville, Tennessee 37232
| | - Thomas R Sutter
- Department of Biology and W. Harry Feinstone Center for Genomic Research, University of Memphis, Memphis, Tennessee 38152, Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire 03755, Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt School of Medicine, Nashville, Tennessee 37232
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Johnson DN, Egner PA, Obrian G, Glassbrook N, Roebuck BD, Sutter TR, Payne GA, Kensler TW, Groopman JD. Quantification of urinary aflatoxin B1 dialdehyde metabolites formed by aflatoxin aldehyde reductase using isotope dilution tandem mass spectrometry. Chem Res Toxicol 2008; 21:752-60. [PMID: 18266327 DOI: 10.1021/tx700397n] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aflatoxin B 1 aldehyde reductases (AFARs), inducible members of the aldo-keto reductase superfamily, convert aflatoxin B 1 dialdehyde derived from the exo- and endo-8,9-epoxides into a number of reduced alcohol products that might be less capable of forming covalent adducts with proteins. An isotope dilution tandem mass spectrometry method for quantification of the metabolites, C-8 monoalcohol, dialcohol, and C-6a monoalcohol, was developed to ascertain their possible role as urinary biomarkers for application to chemoprevention investigations. This method uses a novel (13)C 17-aflatoxin B 1 dialcohol internal standard, synthesized from (13)C 17-aflatoxin B 1 biologically produced by Aspergillus flavus. Chromatographic standards of the alcohols were generated through sodium borohydride reduction of the aflatoxin B 1 dialdehyde. This method was then explored for sensitivity and specificity in urine samples of aflatoxin B 1-dosed rats that were pretreated with 3 H-1,2-dithiole-3-thione to induce the expression of AKR7A1, a rat isoform of AFAR. One of the two known monoalcohols and the dialcohol metabolite were detected in all urine samples. The concentrations were 203.5 +/- 39.0 ng of monoalcohol C-6a/mg of urinary creatinine and 10.0 +/- 1.0 ng of dialcohol/mg of creatinine (mean +/- standard error). These levels represented about 8.0 and 0.4% of the administered aflatoxin B 1 dose that was found in the urine at 24 h, respectively. Thus, this highly sensitive and specific isotope dilution method is applicable to in vivo quantification of urinary alcohol products produced by AFAR. Heretofore, the metabolic fate of the 8,9-epoxides that are critical for aflatoxin toxicities has been measured by biomarkers of lysine-albumin adducts, hepatic and urinary DNA adducts, and urinary mercapturic acids. This urinary detection of the alcohol products directly contributes to the goal of mass balancing the fate of the bioreactive 8,9-epoxides of AFB 1 in vivo.
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Affiliation(s)
- Denise N Johnson
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA
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Barski OA, Tipparaju SM, Bhatnagar A. The aldo-keto reductase superfamily and its role in drug metabolism and detoxification. Drug Metab Rev 2008; 40:553-624. [PMID: 18949601 PMCID: PMC2663408 DOI: 10.1080/03602530802431439] [Citation(s) in RCA: 351] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The aldo-keto reductase (AKR) superfamily comprises enzymes that catalyze redox transformations involved in biosynthesis, intermediary metabolism, and detoxification. Substrates of AKRs include glucose, steroids, glycosylation end-products, lipid peroxidation products, and environmental pollutants. These proteins adopt a (beta/alpha)(8) barrel structural motif interrupted by a number of extraneous loops and helixes that vary between proteins and bring structural identity to individual families. The human AKR family differs from the rodent families. Due to their broad substrate specificity, AKRs play an important role in the phase II detoxification of a large number of pharmaceuticals, drugs, and xenobiotics.
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Affiliation(s)
- Oleg A Barski
- Division of Cardiology, Department of Medicine, Institute of Molecular Cardiology, University of Louisville, Louisville, Kentucky 40202, USA.
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Testa B, Krämer SD. The biochemistry of drug metabolism--an introduction: Part 2. Redox reactions and their enzymes. Chem Biodivers 2007; 4:257-405. [PMID: 17372942 DOI: 10.1002/cbdv.200790032] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This review continues a general presentation of the metabolism of drugs and other xenobiotics started in a recent issue of Chemistry & Biodiversity. This Part 2 presents the numerous oxidoreductases involved, their nomenclature, relevant biochemical properties, catalytic mechanisms, and the very diverse reactions they catalyze. Many medicinally, environmentally, and toxicologically relevant examples are presented and discussed. Cytochromes P450 occupy a majority of the pages of Part 2, but a large number of relevant oxidoreductases are also considered, e.g., flavin-containing monooxygenases, amine oxidases, molybdenum hydroxylases, peroxidases, and the innumerable dehydrogenases/reductases.
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Affiliation(s)
- Bernard Testa
- Department of Pharmacy, University Hospital Centre (CHUV), Rue du Bugnon, CH-1011 Lausanne.
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Tulayakul P, Dong KS, Li JY, Manabe N, Kumagai S. The effect of feeding piglets with the diet containing green tea extracts or coumarin on in vitro metabolism of aflatoxin B1 by their tissues. Toxicon 2007; 50:339-48. [PMID: 17537474 DOI: 10.1016/j.toxicon.2007.04.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Revised: 04/18/2007] [Accepted: 04/18/2007] [Indexed: 10/23/2022]
Abstract
To clarify whether enzymes involved in aflatoxin B1 (AFB1) metabolism in pigs respond to antioxidant agents, the effect of feeding piglets with diets containing green tea extracts (Sunphenon) and coumarin on in vitro AFB1 metabolism by their liver and intestinal tissues was studied. The results showed that coumarin reduced AFB1-DNA adduct formation by both liver and intestinal microsomes, while Sunphenon did not have any effects. Both coumarin and Sunphenon enhanced the glutathione S-transferase (GST) activity to conjugate AFB1 to glutathione GSH in the intestine, although no effects were noted in the liver. Changes of the expression of mRNA of GSTA2 and GSTO1 were not in parallel with the observed changes of GST activity, suggesting that other GST subtypes are involved in the GST activity toward AFB1. As for lipophilic-free AFB1 metabolites, coumarin reduced the liver microsomal conversion of AFB1 to aflatoxin M1 (AFM1) and aflatoxin Q1 (AFQ1), but Sunphenon exerted no effects. Both coumarin and Sunphenon enhanced the conversion of AFB1 to aflatoxicol in the liver. All the results suggest that feeding with a diet containing coumarin affects AFB1 metabolism to enhance AFB1 detoxification through the suppression of P450 enzyme activity in the liver and the enhancement of GST activity in the intestine. Feeding with a diet containing Sunphenon enhances AFB1 detoxification, but the effects are noted mainly in the intestine.
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Affiliation(s)
- P Tulayakul
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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Oppermann U. Carbonyl reductases: the complex relationships of mammalian carbonyl- and quinone-reducing enzymes and their role in physiology. Annu Rev Pharmacol Toxicol 2007; 47:293-322. [PMID: 17009925 DOI: 10.1146/annurev.pharmtox.47.120505.105316] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Carbonyl groups are frequently found in endogenous or xenobiotic compounds. Reactive carbonyls, formed during lipid peroxidation or food processing, and xenobiotic quinones are able to covalently modify DNA or amino acids. They can also promote oxidative stress, the products of which are thought to be an important initiating factor in degenerative diseases or cancer. Carbonyl groups are reduced by an array of distinct NADPH-dependent enzymes, belonging to several oxidoreductase families. These reductases often show broad and overlapping substrate specificities and some well-characterized members, e.g., carbonyl reductase (CBR1) or NADPH-quinone reductase (NQO1) have protective roles toward xenobiotic carbonyls and quinones because metabolic reduction leads to less toxic products, which can be further metabolized and excreted. This review summarizes the current knowledge on structure and function relationships of the major human and mammalian carbonyl reductases identified.
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Affiliation(s)
- Udo Oppermann
- Structural Genomics Consortium, Botnar Research Center, University of Oxford, Oxford, OX3 7LD, United Kingdom.
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Matsunaga T, Shintani S, Hara A. Multiplicity of mammalian reductases for xenobiotic carbonyl compounds. Drug Metab Pharmacokinet 2006; 21:1-18. [PMID: 16547389 DOI: 10.2133/dmpk.21.1] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A variety of carbonyl compounds are present in foods, environmental pollutants, and drugs. These xenobiotic carbonyl compounds are metabolized into the corresponding alcohols by many mammalian NAD(P)H-dependent reductases, which belong to the short-chain dehydrogenase/reductase (SDR) and aldo-keto reductase superfamilies. Recent genomic analysis, cDNA isolation and characterization of the recombinant enzymes suggested that, in humans, the six members of each of the two superfamilies, i.e., total of 12 enzymes, are involved in the reductive metabolism of xenobiotic carbonyl compounds. They comprise three types of carbonyl reductase, dehydrogenase/reductase (SDR family) member 4, 11beta-hydroxysteroid dehydrogenase type 1, L-xylulose reductase, two types of aflatoxin B1 aldehyde reductase, 20alpha-hydroxysteroid dehydrogenase, and three types of 3alpha-hydroxysteroid dehydrogenase. Accumulating data on the human enzymes provide new insights into their roles in cellular and molecular reactions including xenobiotic metabolism. On the other hand, mice and rats lack the gene for a protein corresponding to human 3alpha-hydroxysteroid dehydrogenase type 3, but instead possess additional five or six genes encoding proteins that are structurally related to human hydroxysteroid dehydrogenases. Characterization of the additional enzymes suggested their involvement in species-specific biological events and species differences in the metabolism of xenobiotic carbonyl compounds.
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Abstract
The cytochrome P450 (P450) enzymes are the major catalysts involved in the metabolism of drugs. Bioavailability and toxicity are 2 of the most common barriers in drug development today, and P450 and the conjugation enzymes can influence these effects. The toxicity of drugs can be considered in 5 contexts: on-target toxicity, hypersensitivity and immunological reactions, off-target pharmacology, bioactivation to reactive intermediates, and idiosyncratic drug reactions. The chemistry of bioactivation is reasonably well understood, but the mechanisms underlying biological responses are not. In the article we consider what fraction of drug toxicity actually involves metabolism, and we examine how species and human interindividual variations affect pharmacokinetics and toxicity.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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Tulayakul P, Sakuda S, Dong KS, Kumagai S. Comparative activities of glutathione-S-transferase and dialdehyde reductase toward aflatoxin B1 in livers of experimental and farm animals. Toxicon 2005; 46:204-9. [PMID: 15964045 DOI: 10.1016/j.toxicon.2005.03.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Accepted: 03/25/2005] [Indexed: 11/25/2022]
Abstract
In order to gain a better understanding of the relative activities of glutathione-S-transferase (GST) and aldehyde reductase toward aflatoxin B1 (AFB1) in relation to the variation of species susceptibilities, we studied the in vitro cytosolic GST and reductase activities in liver tissues from male Fischer rats, ICR mice and golden hamsters, adult male rainbow trouts and female piglets. The GST activity was determined by incubating the liver cytosol with glutathione (GSH) and AFB1 in the presence of the hamster liver microsomes to metabolize AFB1 to AFB1-8, 9-epoxide. The reaction product, AFB1 and GSH conjugate (AFB1-GSH), was quantified with HPLC. The reductase activity was determined by incubating liver cytosol with AFB1-dialdehyde, followed by the quantification of the metabolic product, AFB1-dialcohol, with HPLC. All the animal species possessed the GST activities, and AFB1-GSH formed increasingly with the increase of the AFB1 concentration according to the model of first-order enzyme reaction kinetics. The V(max) and K(m) values of the GST activities in rodent species were higher and lower, respectively, than those in the trout and pig, being consistent with the relative susceptibilities to AFB1 of these animal species. However, no relationship was noted between the reductase activity and species susceptibility. Thus, the result of this study shows that GST toward AFB1, but not aldehyde reductase, is a determinant of the variation of species susceptibilities.
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Affiliation(s)
- P Tulayakul
- Laboratory of Veterinary Public Health, Graduate School of Agricultural and Life Sciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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Guengerich FP. Cytochrome P450 oxidations in the generation of reactive electrophiles: epoxidation and related reactions. Arch Biochem Biophys 2003; 409:59-71. [PMID: 12464245 DOI: 10.1016/s0003-9861(02)00415-0] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Much of the interest in the cytochrome P450 (P450) enzymes has been because of oxidation of chemicals to reactive products. The epoxides (oxiranes) have been a major topic of interest with olefins and aryl compounds. Epoxides vary considerably in their reactivity, with t(1/2) varying from 1s to several hours. The stability and reactivity influences not only the overall damage to biological systems but also the site of injury. Transformations of some xenobiotic chemicals may involve products other than epoxides. Chemicals considered here include olefins, aromatic hydrocarbons, heterocycles, vinyl halides, ethyl carbamate, vinyl nitrosamines, and aflatoxin B(1). These compounds either are unsaturated or are transformed to unsaturated products. The epoxides and other products provide a view of the landscape of P450-generated reactive products and the myriad of chemistry involved in the metabolism of drugs and protoxicants. Understanding the chemical nature of reactive products is necessary to develop rational strategies for intervention.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry and Center in Molecular Toxicology, School of Medicine, Vanderbilt University, 638 Robinson Research Building, 23rd and Pierce Avenues, Nashville, TN 37232-0146, USA.
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Kelly VP, Sherratt PJ, Crouch DH, Hayes JD. Novel homodimeric and heterodimeric rat gamma-hydroxybutyrate synthases that associate with the Golgi apparatus define a distinct subclass of aldo-keto reductase 7 family proteins. Biochem J 2002; 366:847-61. [PMID: 12071861 PMCID: PMC1222835 DOI: 10.1042/bj20020342] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2002] [Revised: 06/17/2002] [Accepted: 06/19/2002] [Indexed: 01/07/2023]
Abstract
The aldo-keto reductase (AKR) 7 family is composed of the dimeric aflatoxin B(1) aldehyde reductase (AFAR) isoenzymes. In the rat, two AFAR subunits exist, designated rAFAR1 and rAFAR2. Herein, we report the molecular cloning of rAFAR2, showing that it shares 76% sequence identity with rAFAR1. By contrast with rAFAR1, which comprises 327 amino acids, rAFAR2 contains 367 amino acids. The 40 extra residues in rAFAR2 are located at the N-terminus of the polypeptide as an Arg-rich domain that may form an amphipathic alpha-helical structure. Protein purification and Western blotting have shown that the two AFAR subunits are found in rat liver extracts as both homodimers and as a heterodimer. Reductase activity in rat liver towards 2-carboxybenzaldehyde (CBA) was resolved by anion-exchange chromatography into three peaks containing rAFAR1-1, rAFAR1-2 and rAFAR2-2 dimers. These isoenzymes are functionally distinct; with NADPH as cofactor, rAFAR1-1 has a low K(m) and high activity with CBA, whereas rAFAR2-2 exhibits a low K(m) and high activity towards succinic semialdehyde. These data suggest that rAFAR1-1 is a detoxication enzyme, while rAFAR2-2 serves to synthesize the endogenous neuromodulator gamma-hydroxybutyrate (GHB). Subcellular fractionation of liver extracts showed that rAFAR1-1 was recovered in the cytosol whereas rAFAR2-2 was associated with the Golgi apparatus. The distinct subcellular localization of the rAFAR1 and rAFAR2 subunits was confirmed by immunocytochemistry in H4IIE cells. Association of rAFAR2-2 with the Golgi apparatus presumably facilitates secretion of GHB, and the novel N-terminal domain may either determine the targeting of the enzyme to the Golgi or regulate the secretory process. A murine AKR protein of 367 residues has been identified in expressed sequence tag databases that shares 91% sequence identity with rAFAR2 and contains the Arg-rich extended N-terminus of 40 amino acids. Further bioinformatic evidence is presented that full-length human AKR7A2 is composed of 359 amino acids and also possesses an additional N-terminal domain. On the basis of these observations, we conclude that AKR7 proteins can be divided into two subfamilies, one of which is a Golgi-associated GHB synthase with a unique, previously unrecognized, N-terminal domain that is absent from other AKR proteins.
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MESH Headings
- Alcohol Oxidoreductases/chemistry
- Alcohol Oxidoreductases/metabolism
- Aldehyde Reductase/chemistry
- Aldehyde Reductase/genetics
- Aldehyde Reductase/metabolism
- Aldo-Keto Reductases
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Western
- Catalysis
- Cells, Cultured
- Chromatography, Ion Exchange
- Cloning, Molecular
- Cytosol/enzymology
- Cytosol/metabolism
- DNA, Complementary/metabolism
- Dimerization
- Female
- Golgi Apparatus/metabolism
- Humans
- Immunoblotting
- Immunohistochemistry
- Kinetics
- Liver/enzymology
- Liver/metabolism
- Male
- Mice
- Microscopy, Fluorescence
- Molecular Sequence Data
- Protein Binding
- Protein Structure, Tertiary
- Rats
- Rats, Inbred F344
- Rats, Sprague-Dawley
- Sequence Homology, Amino Acid
- Sodium Oxybate/metabolism
- Subcellular Fractions/metabolism
- Substrate Specificity
- gamma-Aminobutyric Acid/analogs & derivatives
- gamma-Aminobutyric Acid/metabolism
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Affiliation(s)
- Vincent P Kelly
- Biomedical Research Centre, Ninewells Hospital and Medical School, University of Dundee, Scotland, UK
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Abstract
We have characterised a novel aldo-keto reductase (AKR7A5) from mouse liver that is 78% identical to rat aflatoxin dialdehyde reductase AKR7A1 and 89% identical to human succinic semialdehyde (SSA) reductase AKR7A2. AKR7A5 can reduce 2-carboxybenzaldehyde (2-CBA) and SSA as well as a range of aldehyde and diketone substrates. Western blots show that it is expressed in liver, kidney, testis and brain, and at lower levels in skeletal muscle, spleen heart and lung. The protein is not inducible in the liver by dietary ethoxyquin. Immunodepletion of AKR7A5 from liver extracts shows that it is one of the major liver 2-CBA reductases but that it is not the main SSA reductase in this tissue.
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Affiliation(s)
- Alison Hinshelwood
- Department of Pharmaceutical Sciences, University of Strathclyde, 204 George Street, G1 1XW, Glasgow, UK
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41
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Guengerich FP. Common and uncommon cytochrome P450 reactions related to metabolism and chemical toxicity. Chem Res Toxicol 2001; 21:70-83. [PMID: 11409933 DOI: 10.1021/tx700079z] [Citation(s) in RCA: 1107] [Impact Index Per Article: 48.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cytochrome P450 (P450) enzymes catalyze a variety of reactions and convert chemicals to potentially reactive products as well as make compounds less toxic. Most of the P450 reactions are oxidations. The majority of these can be rationalized in the context of an FeO(3+) intermediate and odd electron abstraction/rebound mechanisms; however, other iron-oxygen complexes are possible and alternate chemistries can be considered. Another issue regarding P450-catalyzed reactions is the delineation of rate-limiting steps in the catalytic cycle and the contribution to reaction selectivity. In addition to the rather classical oxidations, P450s also catalyze less generally discussed reactions including reduction, desaturation, ester cleavage, ring expansion, ring formation, aldehyde scission, dehydration, ipso attack, one-electron oxidation, coupling reactions, rearrangement of fatty acid and prostaglandin hydroperoxides, and phospholipase activity. Most of these reactions are rationalized in the context of high-valent iron-oxygen intermediates and Fe(2+) reductions, but others are not and may involve acid-base catalysis. Some of these transformations are involved in the bioactivation and detoxication of xenobiotic chemicals.
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Affiliation(s)
- F P Guengerich
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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