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Lethe MCL, Paris V, Wang X, Chan CTY. Similarities in Structure and Function of UDP-Glycosyltransferase Homologs from Human and Plants. Int J Mol Sci 2024; 25:2782. [PMID: 38474028 PMCID: PMC10932239 DOI: 10.3390/ijms25052782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 02/23/2024] [Accepted: 02/25/2024] [Indexed: 03/14/2024] Open
Abstract
The uridine diphosphate glycosyltransferase (UGT) superfamily plays a key role in the metabolism of xenobiotics and metabolic wastes, which is essential for detoxifying those species. Over the last several decades, a huge effort has been put into studying human and mammalian UGT homologs, but family members in other organisms have been explored much less. Potentially, other UGT homologs can have desirable substrate specificity and biological activities that can be harnessed for detoxification in various medical settings. In this review article, we take a plant UGT homology, UGT71G1, and compare its structural and biochemical properties with the human homologs. These comparisons suggest that even though mammalian and plant UGTs are functional in different environments, they may support similar biochemical activities based on their protein structure and function. The known biological functions of these homologs are discussed so as to provide insights into the use of UGT homologs from other organisms for addressing human diseases related to UGTs.
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Affiliation(s)
- Mary Caroline L. Lethe
- Department of Biomedical Engineering, College of Engineering, University of North Texas, 3940 N Elm Street, Denton, TX 76207, USA (V.P.)
| | - Vincent Paris
- Department of Biomedical Engineering, College of Engineering, University of North Texas, 3940 N Elm Street, Denton, TX 76207, USA (V.P.)
| | - Xiaoqiang Wang
- Department of Biological Sciences, College of Science, University of North Texas, 1155 Union Circle #305220, Denton, TX 76203, USA;
- BioDiscovery Institute, University of North Texas, 1155 Union Circle #305220, Denton, TX 76203, USA
| | - Clement T. Y. Chan
- Department of Biomedical Engineering, College of Engineering, University of North Texas, 3940 N Elm Street, Denton, TX 76207, USA (V.P.)
- BioDiscovery Institute, University of North Texas, 1155 Union Circle #305220, Denton, TX 76203, USA
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2
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Ramunaidu A, Pavankumar P, Ragi N, Ramesh R, Jagannatham MV, Sripadi P. Characterization of isomeric acetyl amino acids and di-acetyl amino acids by LC/MS/MS. JOURNAL OF MASS SPECTROMETRY : JMS 2023; 58:e4982. [PMID: 38031236 DOI: 10.1002/jms.4982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 09/20/2023] [Accepted: 10/11/2023] [Indexed: 12/01/2023]
Abstract
Acetylation of amino acids is important in the molecular biology and biochemistry because they are part of several metabolic pathways. N-acetyl amino acids can form through degradation of N-acetyl proteins or direct acetylation of amino acids by specific enzymes. Acetylation of α-amino acids can be either on the alpha -NH2 or on the side-chain functional group, where both the acetyl products are isomeric and can show different biological roles. Theoretically, all proteinogenic α-amino acids are expected to undergo acetylation and they can be a part of metabolome. Thus, it is essential to detect and identify all the possible acetylated products of α-amino acids for untargeted metabolomics studies. In this study, it is aimed to synthesize and characterize all acetylated products of natural α-amino acids. A total of 20 Nα -acetyl amino acids (1-20), six side-chain acetyl amino acids (21-26), and six diacetyl amino acids (27-32) were synthesized and characterized by liquid chromatography-electrospray ionizationtandem mass spectrometry (LC-ESI-MS/MS). The [M + H]+ ions of all the acetyl amino acids were subjected to MS/MS experiments to obtain their structural information. Apart from the expected loss of (H2 O + CO) (immonium ions), most of the acetyl amino acids specifically showed loss of H2 O and loss of a ketene (C2 H2 O) from [M+H]+ ions. The side-chain acetyl amino acids showed a clear-cut structure specific fragment ions that enabled easy differentiation from their isomeric Nα -acetyl amino acids. The other isomeric/isobaric acetyl amino acids could also be easily distinguished by their MS/MS spectra. The MS/MS of immonium ions of the acetyl amino acids were also studied, and they included characteristic products reflecting the structures of parent Nα -acetyl and side-chain acetyl amino acids.
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Affiliation(s)
- Addipilli Ramunaidu
- Centre for Mass Spectrometry, Department of Analytical and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Pallerla Pavankumar
- Centre for Mass Spectrometry, Department of Analytical and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Nagarjunachary Ragi
- Centre for Mass Spectrometry, Department of Analytical and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, India
| | - Rodda Ramesh
- Centre for Mass Spectrometry, Department of Analytical and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | | | - Prabhakar Sripadi
- Centre for Mass Spectrometry, Department of Analytical and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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3
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Contente ML, Annunziata F, Cannazza P, Donzella S, Pinna C, Romano D, Tamborini L, Barbosa FG, Molinari F, Pinto A. Biocatalytic Approaches for an Efficient and Sustainable Preparation of Polyphenols and Their Derivatives. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:13669-13681. [PMID: 34762407 DOI: 10.1021/acs.jafc.1c05088] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Many sectors of industry, such as food, cosmetics, nutraceuticals, and pharmaceuticals, have increased their interest in polyphenols due to their beneficial properties. These molecules are widely found in Nature (plants) and can be obtained through direct extraction from vegetable matrices. Polyphenols introduced through the diet may be metabolized in the human body via different biotransformations leading to compounds having different bioactivities. In this context, enzyme-catalyzed reactions are the most suitable approach to produce modified polyphenols that not only can be studied for their bioactivity but also can be labeled as green, natural products. This review aims to give an overview of the potential of biocatalysis as a powerful tool for the modification of polyphenols to enhance their bioaccessibility, bioavailability, biological activity or modification of their physicochemical properties. The main polyphenol transformations occurring during their metabolism in the human body have been also presented.
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Affiliation(s)
- Martina Letizia Contente
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria 2, 20133 Milan, Italy
| | - Francesca Annunziata
- Department of Pharmaceutical Sciences (DISFARM), University of Milan, via Mangiagalli 25, 20133 Milan, Italy
| | - Pietro Cannazza
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria 2, 20133 Milan, Italy
| | - Silvia Donzella
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria 2, 20133 Milan, Italy
| | - Cecilia Pinna
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria 2, 20133 Milan, Italy
| | - Diego Romano
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria 2, 20133 Milan, Italy
| | - Lucia Tamborini
- Department of Pharmaceutical Sciences (DISFARM), University of Milan, via Mangiagalli 25, 20133 Milan, Italy
| | - Francisco Geraldo Barbosa
- Department of Organic and Inorganic Chemistry, Sciences Center, Federal University of Ceará, Fortaleza-CE 60455-970, Brazil
| | - Francesco Molinari
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria 2, 20133 Milan, Italy
| | - Andrea Pinto
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria 2, 20133 Milan, Italy
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Mukkavilli R, Gundala SR, Yang C, Jadhav GR, Vangala S, Reid MD, Aneja R. Noscapine recirculates enterohepatically and induces self-clearance. Eur J Pharm Sci 2015; 77:90-9. [PMID: 26026989 DOI: 10.1016/j.ejps.2015.05.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 04/10/2015] [Accepted: 05/26/2015] [Indexed: 01/10/2023]
Abstract
Noscapine (Nos), an antitussive benzylisoquinoline opium alkaloid, is a non-toxic tubulin-binding agent currently in Phase II clinical trials for cancer chemotherapy. While preclinical studies have established its tumor-inhibitory properties in various cancers, poor absorptivity and rapid first-pass metabolism producing several uncharacterized metabolites for efficacy, present an impediment in translating its efficacy in humans. Here we report novel formulations of Nos in combination with dietary agents like capsaicin (Cap), piperine (Pip), eugenol (Eu) and curcumin (Cur) known for modulating Phase I and II drug metabolizing enzymes. In vivo pharmacokinetic (PK), organ toxicity evaluation of combinations, microsomal stability and in vitro cytochrome P450 (CYP) inhibition effects of Nos, Cap and Pip using human liver microsomes were performed. Single-dose PK screening of combinations revealed that the relative exposure of Nos (2 μg h/mL) was enhanced by 2-fold (4 μg h/mL) by Cap and Pip and their plasma concentration-time profiles showed multiple peaking phenomena for Nos indicating enterohepatic recirculation or differential absorption from intestine. CYP inhibition studies confirmed that Nos, Cap and Pip are not potent CYP inhibitors (IC50>1 μM). Repeated oral dosing of Nos, Nos+Cap and Nos+Pip showed lower exposure (Cmax and AUClast) of Nos on day 7 compared to day 1. Nos Cmax decreased from 3087 ng/mL to 684 ng/mL and AUClast from 1024 ng h/mL to 508 ng h/mL. In presence of Cap and Pip, the decrease in Cmax and AUClast of Nos was similar. This may be due to potential enzyme induction leading to rapid clearance of Nos as the trend was observed in Nos alone group also. The lack of effect on intrinsic clearance of Nos suggests that the potential drug biotransformation modulators employed in this study did not contribute toward increased exposure of Nos on repeated dosing. We envision that Nos-induced enzyme induction could alter the therapeutic efficacy of co-administered drugs, hence emphasizing the need for strategic evaluation of the metabolism of Nos to reap its maximum efficacy.
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Affiliation(s)
- Rao Mukkavilli
- Advinus Therapeutics Limited, Karnataka 560058, India; Manipal University, Manipal, Karnataka 576104, India
| | - Sushma R Gundala
- Department of Biology, Georgia State University, Atlanta, GA 30303, United States
| | - Chunhua Yang
- Department of Biology, Georgia State University, Atlanta, GA 30303, United States
| | | | | | - Michelle D Reid
- Department of Pathology, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Ritu Aneja
- Department of Biology, Georgia State University, Atlanta, GA 30303, United States.
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Mazuy C, Helleboid A, Staels B, Lefebvre P. Nuclear bile acid signaling through the farnesoid X receptor. Cell Mol Life Sci 2015; 72:1631-50. [PMID: 25511198 PMCID: PMC11113650 DOI: 10.1007/s00018-014-1805-y] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/04/2014] [Accepted: 12/08/2014] [Indexed: 12/16/2022]
Abstract
Bile acids (BAs) are amphipathic molecules produced from cholesterol by the liver. Expelled from the gallbladder upon meal ingestion, BAs serve as fat solubilizers in the intestine. BAs are reabsorbed in the ileum and return via the portal vein to the liver where, together with nutrients, they provide signals to coordinate metabolic responses. BAs act on energy and metabolic homeostasis through the activation of membrane and nuclear receptors, among which the nuclear receptor farnesoid X receptor (FXR) is an important regulator of several metabolic pathways. Highly expressed in the liver and the small intestine, FXR contributes to BA effects on metabolism, inflammation and cell cycle control. The pharmacological modulation of its activity has emerged as a potential therapeutic strategy for liver and metabolic diseases. This review highlights recent advances regarding the mechanisms by which the BA sensor FXR contributes to global signaling effects of BAs, and how FXR activity may be regulated by nutrient-sensitive signaling pathways.
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Affiliation(s)
- Claire Mazuy
- European Genomic Institute for Diabetes (EGID), 59000 Lille, France
- INSERM UMR1011-Bâtiment J&K, 59000 Lille, France
- University Lille 2, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
| | - Audrey Helleboid
- European Genomic Institute for Diabetes (EGID), 59000 Lille, France
- INSERM UMR1011-Bâtiment J&K, 59000 Lille, France
- University Lille 2, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
| | - Bart Staels
- European Genomic Institute for Diabetes (EGID), 59000 Lille, France
- INSERM UMR1011-Bâtiment J&K, 59000 Lille, France
- University Lille 2, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
| | - Philippe Lefebvre
- European Genomic Institute for Diabetes (EGID), 59000 Lille, France
- INSERM UMR1011-Bâtiment J&K, 59000 Lille, France
- University Lille 2, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
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Reshetnyak VI. Physiological and molecular biochemical mechanisms of bile formation. World J Gastroenterol 2013; 19:7341-7360. [PMID: 24259965 PMCID: PMC3831216 DOI: 10.3748/wjg.v19.i42.7341] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 07/17/2013] [Accepted: 09/29/2013] [Indexed: 02/06/2023] Open
Abstract
This review considers the physiological and molecular biochemical mechanisms of bile formation. The composition of bile and structure of a bile canaliculus, biosynthesis and conjugation of bile acids, bile phospholipids, formation of bile micellar structures, and enterohepatic circulation of bile acids are described. In general, the review focuses on the molecular physiology of the transporting systems of the hepatocyte sinusoidal and apical membranes. Knowledge of physiological and biochemical basis of bile formation has implications for understanding the mechanisms of development of pathological processes, associated with diseases of the liver and biliary tract.
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He YJ, Fang ZZ, Ge GB, Jiang P, Jin HZ, Zhang WD, Yang L. The Inhibitory Effect of 20(S
)-Protopanaxatriol (ppt) Towards UGT1A1 and UGT2B7. Phytother Res 2012; 27:628-32. [DOI: 10.1002/ptr.4755] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 05/05/2012] [Accepted: 05/07/2012] [Indexed: 11/10/2022]
Affiliation(s)
- Ya-Jun He
- School of Pharmacy; Shanghai Jiao Tong University; No. 800, Dongchuan Road Shanghai 200240 PR China
- School of Pharmacy; Second Military Medical University; Guohe Road Shanghai 200433 PR China
| | - Zhong-Ze Fang
- Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences; 457 Zhongshan Road Dalian 116023 PR China
| | - Guang-Bo Ge
- Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences; 457 Zhongshan Road Dalian 116023 PR China
| | - Peng Jiang
- School of Pharmacy; Second Military Medical University; Guohe Road Shanghai 200433 PR China
| | - Hui-Zi Jin
- School of Pharmacy; Shanghai Jiao Tong University; No. 800, Dongchuan Road Shanghai 200240 PR China
| | - Wei-Dong Zhang
- School of Pharmacy; Shanghai Jiao Tong University; No. 800, Dongchuan Road Shanghai 200240 PR China
- School of Pharmacy; Second Military Medical University; Guohe Road Shanghai 200433 PR China
| | - Ling Yang
- Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences; 457 Zhongshan Road Dalian 116023 PR China
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Hiljadnikova Bajro M, Josifovski T, Panovski M, Jankulovski N, Kapedanovska Nestorovska A, Matevska N, Petrusevska N, Dimovski AJ. Promoter length polymorphism in UGT1A1 and the risk of sporadic colorectal cancer. Cancer Genet 2012; 205:163-7. [DOI: 10.1016/j.cancergen.2012.01.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 01/23/2012] [Accepted: 01/30/2012] [Indexed: 10/28/2022]
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Kundu R, Dasgupta S, Biswas A, Bhattacharya S, Pal BC, Bhattacharya S, Rao P, Barua N, Bordoloi M, Bhattacharya S. Carlinoside reduces hepatic bilirubin accumulation by stimulating bilirubin-UGT activity through Nrf2 gene expression. Biochem Pharmacol 2011; 82:1186-97. [DOI: 10.1016/j.bcp.2011.07.069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 06/12/2011] [Accepted: 07/07/2011] [Indexed: 01/21/2023]
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10
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Rajakannan V, Lee HS, Chong SH, Ryu HB, Bae JY, Whang EY, Huh JW, Cho SW, Kang LW, Choe H, Robinson RC. Structural basis of cooperativity in human UDP-glucose dehydrogenase. PLoS One 2011; 6:e25226. [PMID: 21984906 PMCID: PMC3184952 DOI: 10.1371/journal.pone.0025226] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 08/29/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND UDP-glucose dehydrogenase (UGDH) is the sole enzyme that catalyzes the conversion of UDP-glucose to UDP-glucuronic acid. The product is used in xenobiotic glucuronidation in hepatocytes and in the production of proteoglycans that are involved in promoting normal cellular growth and migration. Overproduction of proteoglycans has been implicated in the progression of certain epithelial cancers, while inhibition of UGDH diminished tumor angiogenesis in vivo. A better understanding of the conformational changes occurring during the UGDH reaction cycle will pave the way for inhibitor design and potential cancer therapeutics. METHODOLOGY Previously, the substrate-bound of UGDH was determined to be a symmetrical hexamer and this regular symmetry is disrupted on binding the inhibitor, UDP-α-D-xylose. Here, we have solved an alternate crystal structure of human UGDH (hUGDH) in complex with UDP-glucose at 2.8 Å resolution. Surprisingly, the quaternary structure of this substrate-bound protein complex consists of the open homohexamer that was previously observed for inhibitor-bound hUGDH, indicating that this conformation is relevant for deciphering elements of the normal reaction cycle. CONCLUSION In all subunits of the present open structure, Thr131 has translocated into the active site occupying the volume vacated by the absent active water and partially disordered NAD+ molecule. This conformation suggests a mechanism by which the enzyme may exchange NADH for NAD+ and repolarize the catalytic water bound to Asp280 while protecting the reaction intermediates. The structure also indicates how the subunits may communicate with each other through two reaction state sensors in this highly cooperative enzyme.
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Affiliation(s)
- Venkatachalam Rajakannan
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore
| | - Hui-Sun Lee
- Department of Physiology, University of Ulsan College of Medicine, Seoul, Korea
- Bio-Medical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea
| | - Seon-Ha Chong
- Department of Physiology, University of Ulsan College of Medicine, Seoul, Korea
- Bio-Medical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea
| | - Han-Bong Ryu
- Department of Physiology, University of Ulsan College of Medicine, Seoul, Korea
- Bio-Medical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea
| | - Ji-Young Bae
- Department of Physiology, University of Ulsan College of Medicine, Seoul, Korea
- Bio-Medical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea
| | - Eun-Young Whang
- Department of Biochemistry and Molecular Biology, University of Ulsan College of Medicine, Seoul, Korea
| | - Jae-Wan Huh
- Department of Biochemistry and Molecular Biology, University of Ulsan College of Medicine, Seoul, Korea
| | - Sung-Woo Cho
- Department of Biochemistry and Molecular Biology, University of Ulsan College of Medicine, Seoul, Korea
| | - Lin-Woo Kang
- Department of Advanced Technology Fusion, Kunkuk University, Seoul, Korea
| | - Han Choe
- Department of Physiology, University of Ulsan College of Medicine, Seoul, Korea
- Bio-Medical Institute of Technology, University of Ulsan College of Medicine, Seoul, Korea
- * E-mail:
| | - Robert C. Robinson
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore
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Chang JL, Chen G, Ulrich CM, Bigler J, King IB, Schwarz Y, Li S, Li L, Potter JD, Lampe JW. DNA damage and repair: fruit and vegetable effects in a feeding trial. Nutr Cancer 2010; 62:329-35. [PMID: 20358470 DOI: 10.1080/01635580903407106] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Epidemiologic studies have examined the association between fruit and vegetable (F&V) consumption and the risk of cancer. Several cancer-preventive mechanisms have been proposed, such as antioxidant properties and modulation of biotransformation enzyme activities; both may be associated with reducing DNA damage and hence the mutation rate. We investigated, in a randomized, controlled, crossover feeding trial, the effect of 10 servings/day of botanically defined F&V for 2 wk on endogenous DNA damage; resistance to gamma -irradiation damage; and DNA repair capacity in lymphocytes, measured by the Comet assay. We also explored the association between the UGT1A1*28 polymorphism and serum bilirubin concentrations and DNA damage and repair measures. Healthy men (n = 11) and women (n = 17), age 20 to 40 yr, provided blood samples at the end of each feeding period. Overall, F&V did not affect DNA damage and repair measures in lymphocytes. The number of UGT1A1*28 alleles was inversely associated with sensitivity to gamma -irradiation exposure and DNA repair capacity, but a biological mechanism to explain this association is unclear. A larger sample size is needed to investigate the association between bilirubin concentrations and endogenous DNA damage. With inconsistent findings in the literature, additional dietary intervention studies on the effect of F&V on DNA damage and repair are needed.
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Computational analysis of the quaternary structural changes induced by point mutations in human UDP-glucose dehydrogenase. Arch Biochem Biophys 2009; 486:35-43. [PMID: 19358821 DOI: 10.1016/j.abb.2009.03.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 03/12/2009] [Accepted: 03/30/2009] [Indexed: 11/23/2022]
Abstract
UDP-glucose dehydrogenase (UGDH) is an enzyme catalyzing the conversion of UDP-glucose to UDP-glucuronic acid. Site-directed mutagenesis studies have revealed that human UGDH (hUGDH) has distinct oligomeric states that vary with different point mutations. In this study we have investigated how the changes in the oligomer-forming propensity may be involved in the thermal motion of wild-type hUGDH and its mutants, using normal mode analysis (NMA). Our results show that the perturbation caused by the mutation of a residue at a considerably distant location from the oligomeric interfaces is preferentially distributed throughout specific sites, especially the large flexible regions in the hUGDH structure, thereby changing the motional fluctuation pattern at the oligomeric interfaces. A large-magnitude cooperative motion at the oligomeric interfaces is a critical factor in interfering with the hexamer formation of the enzyme. In particular, structural stability at the dimeric interface is necessary to retain the hexameric structure of hUGDH.
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13
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Calafat AM, Weuve J, Ye X, Jia LT, Hu H, Ringer S, Huttner K, Hauser R. Exposure to bisphenol A and other phenols in neonatal intensive care unit premature infants. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:639-44. [PMID: 19440505 PMCID: PMC2679610 DOI: 10.1289/ehp.0800265] [Citation(s) in RCA: 188] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Accepted: 12/10/2008] [Indexed: 04/14/2023]
Abstract
OBJECTIVE We previously demonstrated that exposure to polyvinyl chloride plastic medical devices containing di(2-ethylhexyl) phthalate (DEHP) was associated with higher urinary concentrations of several DEHP metabolites in 54 premature infants in two neonatal intensive care units than in the general population. For 42 of these infants, we evaluated urinary concentrations of several phenols, including bisphenol A (BPA), in association with the use of the same medical devices. MEASUREMENTS We measured the urinary concentrations of free and total (free plus conjugated) species of BPA, triclosan, benzophenone-3, methyl paraben, and propyl paraben. RESULTS The percentage of BPA present as its conjugated species was > 90% in more than three-quarters of the premature infants. Intensity of use of products containing DEHP was strongly associated with BPA total concentrations but not with any other phenol. Adjusting for institution and sex, BPA total concentrations among infants in the group of high use of DEHP-containing products were 8.75 times as high as among infants in the low use group (p < 0.0001). Similarly, after adjusting for sex and DEHP-containing product use category, BPA total concentrations among infants in Institution A were 16.6 times as high as those among infants in Institution B (p < 0.0001). CONCLUSION BPA geometric mean urinary concentration (30.3 microg/L) among premature infants undergoing intensive therapeutic medical interventions was one order of magnitude higher than that among the general population. Conjugated species were the primary urinary metabolites of BPA, suggesting that premature infants have some capacity to metabolize BPA. The differences in exposure to BPA by intensity of use of DEHP-containing medical products highlight the need for further studies to determine the specific source(s) of exposure to BPA.
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Affiliation(s)
- Antonia M Calafat
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, USA.
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14
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Kundu R, Dasgupta S, Biswas A, Bhattacharya A, Pal BC, Bandyopadhyay D, Bhattacharya S, Bhattacharya S. Cajanus cajan Linn. (Leguminosae) prevents alcohol-induced rat liver damage and augments cytoprotective function. JOURNAL OF ETHNOPHARMACOLOGY 2008; 118:440-7. [PMID: 18584980 DOI: 10.1016/j.jep.2008.05.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 04/29/2008] [Accepted: 05/09/2008] [Indexed: 05/22/2023]
Abstract
AIM OF THE STUDY Cajanus cajan Linn. (Leguminosae) is a nontoxic edible herb, widely used in Indian folk medicine for the prevention of various liver disorders. In the present study we have demonstrated that methanol-aqueous fraction (MAF2) of Cajanus cajan leaf extract could prevent the chronically treated alcohol induced rat liver damage. MATERIALS AND METHODS Chronic doses of alcohol (3.7 g/ kg) orally administered to rats for 28 days and liver function marker enzymes such as GPT, GOT, ALP and anti-oxidant enzyme activities were determined. Effect of MAF2 at a dose of 50mg/kg body weight on alcohol treated rats was noted. RESULTS Alcohol effected significant increase in liver marker enzyme activities and reduced the activities of anti-oxidant enzymes. Co-administration of MAF2 reversed the liver damage due to alcohol; it decreased the activities of liver marker enzymes and augmented antioxidant enzyme activities. We also demonstrate significant decrease of the phase II detoxifying enzyme, UDP-glucuronosyl transferase (UGT) activity along with a three- and two-fold decrease of UGT2B gene and protein expression respectively. MAF2 co-administration normalized UGT activity and revived the expression of UGT2B with a concomitant expression and nuclear translocation of Nrf2, a transcription factor that regulates the expression of many cytoprotective genes. CONCLUSION Cajanus cajan extract therefore shows a promise in therapeutic use in alcohol induced liver dysfunction.
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Affiliation(s)
- Rakesh Kundu
- Department of Zoology, School of Life Science, Visva-Bharati A Central University, Santiniketan, India
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Akizawa E, Koiwai K, Hayano T, Maezawa S, Matsushita T, Koiwai O. Direct binding of ligandin to uridine 5'-diphosphate glucuronosyltransferase 1A1. Hepatol Res 2008; 38:402-9. [PMID: 18021224 DOI: 10.1111/j.1872-034x.2007.00285.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM Bilirubin, a final degradation product of heme produced mainly in the spleen, is carried to the liver through its binding to albumin in the blood circulation. After its transport to hepatocytes, ligandin (glutathione S-transferase; GST) carries bilirubin to the endoplasmic reticulum (ER). uridine 5'-diphosphate-glucuronosyltransferase 1A1 (UGT1A1) glucuronidates bilirubin for solubilization in the ER. METHODS By GST pull-down and co-immunoprecipitation assays, GSTA2, a member of the alpha-class of GST, was observed to directly bind to UGT1A1 through the region present inside the ER. RESULTS GSTA2 was detected in the microsomal fraction together with the cytosolic fraction after hepatocyte fractionation. CONCLUSION These results strongly suggest that bilirubin is directly delivered to UGT1A1 from ligandin for glucuronidation.
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Affiliation(s)
- Emi Akizawa
- Department of Applied Biological Science, Tokyo University of Science, Chiba, Japan
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16
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Abstract
Cholestasis is a common complication of bacterial infections and sepsis. This article gives a comprehensive overview of the underlying molecular mechanisms of sepsis-associated cholestasis and jaundice, their clinical presentation, and diagnostic and therapeutic management.
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Huh JW, Yang SJ, Hwang EY, Choi MM, Lee HJ, Kim EA, Choi SY, Choi J, Hong HN, Cho SW. Alteration of the quaternary structure of human UDP-glucose dehydrogenase by a double mutation. BMB Rep 2008; 40:690-6. [PMID: 17927902 DOI: 10.5483/bmbrep.2007.40.5.690] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
There are conflicting views for the polymerization process of human UDP-glucose dehydrogenase (UGDH) and no clear evidence has been reported yet. Based on crystal coordinates for Streptococcus pyogenes UGDH, we made double mutant A222Q/S233G. The double mutagenesis had no effects on expression, stability, and secondary structure. Interestingly, A222Q/S233G was a dimeric form and showed an UGDH activity, although it showed increased Km values for substrates. These results suggest that Ala222 and Ser233 play an important role in maintaining the hexameric structure and the reduced binding affinities for substrates are attributable to its altered subunit communication although quaternary structure may not be critical for catalysis.
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Affiliation(s)
- Jae-Wan Huh
- Department of Biochemistry and Molecular Biology, University of Ulsan College of Medicine, Seoul 138-736, Korea
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18
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Hrebícek M, Jirásek T, Hartmannová H, Nosková L, Stránecký V, Ivánek R, Kmoch S, Cebecauerová D, Vítek L, Mikulecký M, Subhanová I, Hozák P, Jirsa M. Rotor-type hyperbilirubinaemia has no defect in the canalicular bilirubin export pump. Liver Int 2007; 27:485-91. [PMID: 17403188 DOI: 10.1111/j.1478-3231.2007.01446.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
BACKGROUND The cause of Rotor syndrome (RS), a rare-familial conjugated hyperbilirubinaemia with normal liver histology, is unclear. We hypothesized that RS can be an allelic variant of Dubin-Johnson syndrome, caused by mutation in ABCC2, and investigated ABCC2 (gene) and ABCC2 (protein) in two patients with RS. METHODS A 57-year-old male presented with a 5-year history of predominantly conjugated hyperbilirubinaemia (170 micromol/l). Urinary porphyrin excretion was increased; cholescintigraphy revealed no chromoexcretion. A 68-year-old male presented with lifelong conjugated hyperbilirubinaemia (85 micromol/l). Bromosulfophthalein elimination was typical for RS. Both patients had histologically normal liver, without pigment. ABCC2 expression was investigated by confocal fluorescence microscopy. ABCC2 was sequenced from genomic DNA and cDNA, and exon deletions/duplications were sought by comparative genomic hybridization on a custom micro-array. RESULTS In both patients, ABCC2 was expressed unremarkably at the apical membrane of hepatocytes and no sequence alterations were found in 32 exons, adjacent intronic regions and the promoter region of ABCC2. CONCLUSIONS Rotor-type hyperbilirubinaemia is not an allelic variant of ABCC2 deficiency.
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Affiliation(s)
- Martin Hrebícek
- Institute of Inherited Metabolic Diseases, Charles University 1st Faculty of Medicine, Prague, Czech Republic
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19
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Chang JL, Bigler J, Schwarz Y, Li SS, Li L, King IB, Potter JD, Lampe JW. UGT1A1 polymorphism is associated with serum bilirubin concentrations in a randomized, controlled, fruit and vegetable feeding trial. J Nutr 2007; 137:890-7. [PMID: 17374650 DOI: 10.1093/jn/137.4.890] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
UDP-glucuronosyltransferase (UGT) 1A1 glucuronidates bilirubin, estrogens, and exogenous compounds, including dietary carcinogens. The UGT1A1*28 polymorphism, characterized by variation in the number of thymine-adenine repeats in the promoter region, modulates UGT1A1 transcription. Observational and in vitro studies suggest that certain phytochemicals may increase UGT activity. We investigated, in a randomized, controlled, crossover feeding trial, whether approximately 10 servings/d (doses adjusted for body weight) of crucifers, soy, and citrus for 2 wk compared with a fruit- and vegetable-free basal diet affected UGT1A1 activity as measured by serum bilirubin concentrations and whether effects were modulated by the UGT1A1*28 polymorphism. Healthy men (n = 32) and women (n = 31), aged 20-40 y, enrolled based on UGT1A1 genotype, completed the study. We measured bilirubin in blood collected at d 8 and d 15 of each feeding period. Overall, fruit and vegetables (F&V) did not affect serum bilirubin; however, among 7/7 individuals, d 8 total (P = 0.057) and indirect (unconjugated) (P = 0.051) bilirubin tended to be lower when individuals consumed the F&V diet (28.97 +/- 2.36 micromol/L and 25.97 +/- 2.15 micromol/L) compared with the basal diet (32.46 +/- 2.63 micromol/L and 29.31 +/- 2.43 micromol/L). We no longer detected this difference at d 15, by which time bilirubin had also decreased when participants consumed the basal diet. Additionally, intervention effects on bilirubin were restricted to women with 7/7 genotype (P = 0.002). These results suggest that serum bilirubin glucuronidation is modulated by dietary intervention, but factors such as UGT1A1 genotype and sex may affect the response to diet.
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Affiliation(s)
- Jyh-Lurn Chang
- Interdisciplinary Graduate Program in Nutritional Sciences, Department of Epidemiology, University of Washington, Seattle, WA 98195, USA
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20
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Affiliation(s)
- Nisha Chand
- Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, Virginia Commonwealth University Medical Center, Richmond, VA 23298-0341, USA
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21
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Linster CL, Van Schaftingen E. Glucuronate, the precursor of vitamin C, is directly formed from UDP-glucuronate in liver. FEBS J 2006; 273:1516-27. [PMID: 16689937 DOI: 10.1111/j.1742-4658.2006.05172.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The conversion of UDP-glucuronate to glucuronate, usually thought to proceed by way of glucuronate 1-phosphate, is a site for short-term regulation of vitamin C synthesis by metyrapone and other xenobiotics in isolated rat hepatocytes. Our purpose was to explore the mechanism of this effect in cell-free systems. Metyrapone and other xenobiotics stimulated, by approximately threefold, the formation of glucuronate from UDP-glucuronate in liver extracts enriched with ATP-Mg, but did not affect the formation of glucuronate 1-phosphate from UDP-glucuronate or the conversion of glucuronate 1-phosphate to glucuronate. This and other data indicated that glucuronate 1-phosphate is not an intermediate in glucuronate formation from UDP-glucuronate, suggesting that this reaction is catalysed by a 'UDP-glucuronidase'. UDP-glucuronidase was present mainly in the microsomal fraction, where its activity was stimulated by UDP-N-acetylglucosamine, known to stimulate UDP-glucuronosyltransferases by enhancing the transport of UDP-glucuronate across the endoplasmic reticulum membrane. UDP-glucuronidase and UDP-glucuronosyltransferases displayed similar sensitivities to various detergents, which stimulated at low concentrations and generally inhibited at higher concentrations. Substrates of glucuronidation inhibited UDP-glucuronidase activity, suggesting that the latter is contributed by UDP-glucuronosyltransferase(s). Inhibitors of beta-glucuronidase and esterases did not affect the formation of glucuronate, arguing against the involvement of a glucuronidation-deglucuronidation cycle. The sensitivity of UDP-glucuronidase to metyrapone and other stimulatory xenobiotics was lost in washed microsomes, even in the presence of ATP-Mg, but it could be restored by adding a heated liver high-speed supernatant or CoASH. In conclusion, glucuronate formation in liver is catalysed by a UDP-glucuronidase which is closely related to UDP-glucuronosyltransferases. Metyrapone and other xenobiotics stimulate UDP-glucuronidase by antagonizing the inhibition exerted, presumably indirectly, by a combination of ATP-Mg and CoASH.
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Affiliation(s)
- Carole L Linster
- Laboratory of Physiological Chemistry, Université Catholique de Louvain and the Christian de Duve Institute of Cellular Pathology, Brussels, Belgium
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22
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Yu C, Ritter JK, Krieg RJ, Rege B, Karnes TH, Sarkar MA. EFFECT OF CHRONIC RENAL INSUFFICIENCY ON HEPATIC AND RENAL UDP-GLUCURONYLTRANSFERASES IN RATS. Drug Metab Dispos 2006; 34:621-7. [PMID: 16415115 DOI: 10.1124/dmd.105.006601] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Significant evidence exists regarding altered CYP450 enzymes in chronic renal insufficiency (CRI), although none exists for the phase II enzymes. The objective of this study was to investigate the effect of CRI on hepatic and renal UDP-glucuronyltransferase (UGT) enzymes. Three groups of rats were included: CRI induced by the 5/6th nephrectomy model, control, and control pair-fed (CPF) rats. UGT activities were determined in liver and kidney microsomes by the 3- and 17-glucuronidation of beta-estradiol (E2-3G and E2-17G), glucuronidation of 4-methylumbelliferone (4-MUG), and 3-glucuronidation of morphine (M3G). UGT isoforms responsible for these catalytic activities were screened using recombinant rat UGT1A1, UGT1A2, UGT1A3, UGT1A7, UGT2B2, UGT2B3, and UGT2B8. UGT protein levels were examined by Western blot analysis using polyclonal antibodies. There was no significant difference between CRI and CPF rats in hepatic and/or renal E2-3G (UGT1A1), E2-17G (UGT2B3), 4-MUG (UGT1A6), and M3G (UGT2B1) formation. Formation of E2-17G and 4-MUG in the liver and E2-3G and 4-MUG in the kidney was significantly reduced (p < 0.05) in CPF and CRI rats compared with control rats. The down-regulated glucuronidation activities were accompanied by corresponding reductions in protein content of specific UGT isoforms. These results suggest that CRI does not seem to influence the protein levels or catalytic activity of most of the major hepatic or renal UGT enzymes. The observed down-regulation of hepatic and renal UGTs in CRI and CPF rats could be caused by restricted food intake in these groups of rats.
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Affiliation(s)
- Chuanhui Yu
- Department of Pharmaceutics, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia, USA
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23
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Beauchef G, Kypriotou M, Chadjichristos C, Widom RL, Porée B, Renard E, Moslemi S, Wegrowski Y, Maquart FX, Pujol JP, Galéra P. c-Krox down-regulates the expression of UDP–glucose dehydrogenase in chondrocytes. Biochem Biophys Res Commun 2005; 333:1123-31. [PMID: 15982635 DOI: 10.1016/j.bbrc.2005.06.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Accepted: 06/02/2005] [Indexed: 11/26/2022]
Abstract
Chondrocyte glycosaminoglycan (GAG) synthesis is regulated by the availability of UDP-glucuronate, the substrate of glucuronosyl transferases which form the GAG chains in proteoglycans and hyaluronan. UDP-glucose dehydrogenase (UDPGD) is therefore a key enzyme in the synthesis of UDP-glucuronate from glucose. However, the mechanisms regulating its expression in chondrocytes are not fully understood. We investigated the effect of c-Krox, a zinc-finger transcription factor previously shown to modulate several matrix genes, on the synthesis of GAG and transcriptional activity of several UDPGD gene promoter constructs, using transient transfection and decoy experiments in rabbit articular chondrocytes (RACs). We show that overexpression of c-Krox inhibits radiosulfate incorporation into neosynthesized GAG and that the effect was mediated by a cis-sequence located between +18 and +39bp of the UDPGD gene. Since that sequence can also bind Sp1/Sp3 factors, it is likely that c-Krox acts in concert with these proteins to modulate the UDPGD gene expression in articular chondrocytes.
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Affiliation(s)
- Gallic Beauchef
- Laboratory of Connective Tissue Biochemistry, Faculty of Medicine, Caen, France
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Peterson S, Bigler J, Horner NK, Potter JD, Lampe JW. Cruciferae interact with the UGT1A1*28 polymorphism to determine serum bilirubin levels in humans. J Nutr 2005; 135:1051-5. [PMID: 15867280 DOI: 10.1093/jn/135.5.1051] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
UDP-glucuronosyltransferase (UGT) 1A1 is a conjugating biotransformation enzyme that plays a role in maintaining levels of endogenous compounds (e.g., bilirubin) and handling exogenous compounds, including carcinogens. The UGT1A1*28 polymorphism results in decreased UGT1A1 promoter activity due to 7 thymine-adenine (TA) repeats instead of the commonly found 6 repeats. Studies indicate that foods from the botanical families Cruciferae (e.g., broccoli), Rutaceae (citrus), Liliaceae (e.g., onions), and Leguminosae (legumes) may increase UGT activity. We investigated, in an observational study, whether foods from these botanical groups were associated with increased UGT1A1 activity as indicated by serum bilirubin concentrations and whether the effect varied by UGT1A1*28 genotype, comparing those homozygous for the [TA](7)-repeat allele (7/7) to homozygous wild-types (6/6) and heterozygotes (6/7) combined. Healthy volunteers completed 3-d food records. Blood samples were drawn for genomic DNA collection and bilirubin measures. For total, direct, and indirect bilirubin measures, there was no significant association with any botanical group independently. There was a significant inverse association between all 3 bilirubin measures and interaction of UGT1A1*28 genotype with Cruciferae intake (P < 0.02 for each measure); individuals with the 7/7 genotype had reduced bilirubin concentrations with increased intake of cruciferous vegetables, whereas individuals with the 6/6 or 6/7 genotype did not. With regard to UGT1A1-conjugated carcinogens (e.g., heterocyclic amines, polycyclic aromatic hydrocarbons), individuals with decreased UGT1A1 activity due to the 7/7 genotype may be at greater risk for carcinogenesis, but our results imply that they also may have greater opportunity to decrease that risk through dietary intervention.
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Affiliation(s)
- Sabrina Peterson
- Interdisciplinary Graduate Program in Nutritional Sciences, Department of Epidemiology, University of Washington, Seattle, WA, USA
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25
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Taura KI, Naito E, Ishii Y, Mori MA, Oguri K, Yamada H. Cytochrome P450 1A1 (CYP1A1) inhibitor alpha-naphthoflavone interferes with UDP-glucuronosyltransferase (UGT) activity in intact but not in permeabilized hepatic microsomes from 3-methylcholanthrene-treated rats: possible involvement of UGT-P450 interactions. Biol Pharm Bull 2004; 27:56-60. [PMID: 14709899 DOI: 10.1248/bpb.27.56] [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] [Indexed: 11/22/2022]
Abstract
The effects of cytochrome P450 (P450, CYP) ligands and permeabilization of microsomes on 3-hydroxybenzo(a)pyrene [3-OH-B(a)P] glucuronidation mediated by rat hepatic microsomes were studied. While the UDP-glucuronosyltransferase (UGT) activity with non-permeabilized microsomes from 3-methylcholanthrene (MC)-treated rats was markedly reduced by alpha-naphthoflavone (NF), this inhibitor had hardly any effect when permeabilized microsomes were used in which the inhibitor was expected to have easy access to UGT. Kinetic analysis indicated that the inhibitory effect of alpha-NF is competitive. These results suggest that a UGT isoform(s) involved in 3-OH-B(a)P glucuronidation is interfered by a CYP1A inhibitor via a mechanism dependent on the intact nature of microsomal membranes in MC-treated rats. It is likely that P450 functions as a substrate transporter for some isoforms of UGT via possible interactions between UGT and P450.
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Affiliation(s)
- Ken-ichiro Taura
- Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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Grant DJ, Hall IJ, Eastmond DA, Jones IM, Bell DA. Bilirubin UDP-glucuronosyltransferase 1A1 (UGT1A1) gene promoter polymorphisms and HPRT, glycophorin A, and micronuclei mutant frequencies in human blood. Mutat Res 2004; 560:1-10. [PMID: 15099818 DOI: 10.1016/j.mrgentox.2004.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2003] [Revised: 12/22/2003] [Accepted: 01/29/2004] [Indexed: 11/21/2022]
Abstract
A dinucleotide repeat polymorphism (5-, 6-, 7-, or 8-TA units) has been identified within the promoter region of UDP-glucuronosyltransferase 1A1 (UGT1A1) gene. The 7-TA repeat allele has been associated with elevated serum bilirubin levels that cause a mild hyperbilirubinemia (Gilbert's syndrome). Studies suggest that promoter transcriptional activity of UGT1A1 is inversely related to the number of TA repeats, and that unconjugated bilirubin concentration increases directly with the number of TA repeat elements. Because bilirubin is a known antioxidant, we hypothesized that UGT1A1 repeats associated with higher bilirubin may be protective against oxidative damage. We examined the effect of UGT1A1 genotype on somatic mutant frequency in the hypoxanthine-guanine phosphoribosyl-transferase (HPRT) gene in human lymphocytes and the glycophorin A (GPA) gene of red blood cells (both N0, NN mutants), and the frequency of lymphocyte micronuclei (both kinetochore (K)-positive or micronuclei K-negative) in 101 healthy smoking and nonsmoking individuals. As hypothesized, genotypes containing 7- and 8-TA displayed marginally lower GPA_NN mutant frequency relative to 5/5, 5/6, 6/6 genotypes ( [Formula: see text] ). In contrast, our analysis showed that lower expressing UGT1A1 alleles (7- and 8-TA) were associated with modestly increased HPRT mutation frequency ( [Formula: see text] ), while the same low-expression genotypes were not significantly associated with micronuclei frequencies (K-positive or K-negative) when compared to high-expression genotypes (5- and 6-TA). We found weak evidence that UGT1A1 genotypes containing 7- and 8-TA were associated with increased GPA_NØ mutant frequency relative to 5/5, 5/6, 6/6 genotypes ( [Formula: see text] ). These data suggest that UGT1A1 genotype may modulate somatic mutation of some types, in some cell lineages, by a mechanism not involving bilirubin antioxidant activity. More detailed studies examining UGT1A1 promoter variation, oxidant/antioxidant balance and genetic damage will be needed.
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Affiliation(s)
- Delores J Grant
- Environmental Genomics Section, Laboratory of Computational Biology and Risk Assessment, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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Schulpis KH, Gavrili S, Tjamouranis J, Karikas GA, Kapiki A, Costalos C. The effect of neonatal jaundice on biotinidase activity. Early Hum Dev 2003; 72:15-24. [PMID: 12706308 DOI: 10.1016/s0378-3782(02)00097-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Jaundice is one of the most common and one of the vexing problems that can occur in newborns. A newborn screening test for biotinidase deficiency has been added to many national screening programmes. AIM To clarify the problem of false-positive screening tests in neonates, especially in term babies, we evaluated the biotinidase activity in the serum of fullterm, premature and small-for-dates newborn infants with jaundice. METHODS 1296 fullterms (controls N=426), 246 prematures (controls N=86) and 156 small-for-dates babies (controls N=38) aged 2-3 days with jaundice were included in the study. In jaundiced neonates and controls, 3.0 ml of blood was drawn for the evaluation of total bilirubin (t.bil), liver enzymes and biotinidase activity in the serum using a fluorimetric method. In order to test whether or not t.bil causes an artifact in the previous method, biotinidase activity was also evaluated in a number of jaundiced newborns using an HPLC method. Additionally, a preliminary in vitro experiment was carried out to test whether t.bil is an inhibitor of the enzyme. RESULTS Biotinidase activities in the group of controls of prematures (3.30+/-1.2 mmol/min/l) and small-for-dates babies (3.34+/-0.8 mmol/min/l) were lower than those of term babies (4.99+/-1.1 mmol/min/l, p<0.001). T.bil and liver enzymes showed a statistically significant inverse correlation with biotinidase activity (p<0.001) in all the jaundiced infants of this study. Additionally, biotinidase activity, evaluated in a number of neonates with both fluorimetric and HPLC methods showed similar results. Preincubation of the serum enzyme with t.bil (>10 mg/dl) resulted in a 50% or more inhibition. CONCLUSIONS (a) Low biotinidase activity was found in term babies, prematures and small-for-dates with jaundice. (b) The low activity of the enzyme could be due to their impaired liver function. (c) The high t.bil levels in the studied groups may play the role of an "inhibitor" of the enzyme. (d) Gestational age as well as t.bil levels should always be written on Guthrie cards for a correct evaluation of biotinidase activity.
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Affiliation(s)
- Kleopatra H Schulpis
- Institute of Child Health, "Aghia Sophia" Children's Hospital, 11527, Athens, Greece.
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Senay C, Jedlitschky G, Terrier N, Burchell B, Magdalou J, Fournel-Gigleux S. The importance of cysteine 126 in the human liver UDP-glucuronosyltransferase UGT1A6. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1597:90-6. [PMID: 12009407 DOI: 10.1016/s0167-4838(02)00266-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The human UDP-glucuronosyltransferase 1A6 (UGT1A6) isoform is actively involved in the detoxication of phenolic compounds. In an effort to gain insight on active-site amino acids, we investigated the functional relevance of cysteinyl residues in the glucuronidation process. The enzyme was irreversibly inactivated upon exposure to thiol-specific reagents, especially N-phenylmaleimide. Site-directed mutagenesis of the conserved Cys126 into valine led to a fully inactive mutant, whereas conservative substitution with serine significantly restored the glucuronidation activity toward 4-methylumbelliferone used as a reference substrate. This mutant exhibited a reduced affinity toward the acceptor substrate, as evidenced by a 10-times increase in K(m) value, compared to the wild-type enzyme. The two mutations did not alter the stability of UGT1A6 nor change the subcellular localization of the protein in the endoplasmic reticulum of recombinant cells. These results support the conclusion that Cys126 is an essential residue for the integrity of the substrate binding site of UGT1A6.
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Affiliation(s)
- Claire Senay
- UMR 7561 CNRS-Université Henri Poincaré Nancy 1, Faculté de Médecine, 9, avenue de la Forêt de Haye, BP184 54505 Vandoeuvre-lès-Nancy Cedex, France
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29
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Grant DJ, Bell DA. Bilirubin UDP-glucuronosyltransferase1A1 gene polymorphisms: Susceptibility to oxidative damage and cancer? Mol Carcinog 2001. [DOI: 10.1002/1098-2744(200012)29:4<198::aid-mc1001>3.0.co;2-k] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
The majority of studies of fetal hepatic elimination have concentrated on the expression and activity of the metabolizing enzymes, but the unique physiologic milieu of the fetal liver should also be considered. The basic structure of the liver is formed by the end of the first trimester. The fetal hepatic circulation differs substantially from that of the adult in that there is an extra input vessel, the umbilical vein, and there is shunting of 30-70% of hepatic blood flow via the ductus venosus. The left and right lobes of the fetal liver seem to function independently with respect to a variety of biochemical parameters, due at least in part to the lower oxygen supply to the right lobe. The zonation of drug-metabolizing enzymes along the hepatic acinus, which is prominent in the adult liver, is absent in the fetal liver. Unlike rodent species, the human fetal liver has a significant capacity for drug metabolism. Of the oxidative enzymes, CYP3A7 accounts for up to 50% of total fetal hepatic cytochrome P450 content. Expression of this enzyme decreases dramatically after birth. CYP1A1 and CYP2D6 have also been detected in human fetal liver, but whether CYP2E1 is expressed remains controversial. Several other cytochrome P450s have been identified and await characterization. Fetal hepatic drug conjugation may prolong fetal exposure to the metabolites produced, which, being more water soluble, do not readily cross the placenta back to the mother and, if excreted in fetal urine, can be recycled in the fetus via amniotic fluid and fetal swallowing. Limited activity of glucuronidation enzymes has been demonstrated in human fetal liver in contrast to the activity of sulfation enzymes, which is significant. Limited in vivo studies in fetal sheep have demonstrated significant fetal hepatic drug elimination, and this has been confirmed in studies of the isolated perfused fetal sheep liver. Our understanding of fetal hepatic elimination processes has advanced steadily over the years. Future developments, however, should consider more fully the influence of the unique physiological milieu of the fetal liver, in addition to the expression and activity of drug metabolizing enzymes.
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Affiliation(s)
- J A Ring
- Department of Medicine, University of Melbourne, Austin, Australia
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31
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Radominska-Pandya A, Czernik PJ, Little JM, Battaglia E, Mackenzie PI. Structural and functional studies of UDP-glucuronosyltransferases. Drug Metab Rev 1999; 31:817-99. [PMID: 10575553 DOI: 10.1081/dmr-100101944] [Citation(s) in RCA: 360] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
UDP-Glucuronosyltransferases (UGTs) are glycoproteins localized in the endoplasmic reticulum (ER) which catalyze the conjugation of a broad variety of lipophilic aglycon substrates with glucuronic acid using UDP-glucuronic acid (UDP-GIcUA) as the sugar donor. Glucuronidation is a major factor in the elimination of lipophilic compounds from the body. In this review, current information on the substrate specificities of UGT1A and 2B family isoforms is discussed. Recent findings with regard to UGT structure and topology are presented, including a dynamic topological model of UGTs in the ER. Evidence from experiments on UGT interactions with inhibitors directed at specific amino acids, photoaffinity labeling, and analysis of amino acid alignments suggest that UDP-GIcUA interacts with residues in both the N- and C-terminal domains, whereas aglycon binding sites are localized in the N-terminal domain. The amino acids identified so far as crucial for substrate binding and catalysis are arginine, lysine, histidine, proline, and residues containing carboxylic acid. Site-directed mutagenesis experiments are critical for unambiguous identification of the active-site architecture.
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Affiliation(s)
- A Radominska-Pandya
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock 72205, USA.
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32
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Bernard P, Goudonnet H, Artur Y, Desvergne B, Wahli W. Activation of the mouse TATA-less and human TATA-containing UDP-glucuronosyltransferase 1A1 promoters by hepatocyte nuclear factor 1. Mol Pharmacol 1999; 56:526-36. [PMID: 10462540 DOI: 10.1124/mol.56.3.526] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
UDP-glucuronosyltransferase (UGT) 1A1 (UGT1A1) catalyzes the glucuronidation of bilirubin in liver. Among all UGT isoforms identified to date, it is the only relevant bilirubin-glucuronidating enzyme in human. Because glucuronoconjugation is the major route of bilirubin elimination, any genetic alteration that affects bilirubin glucuronosyltransferase activity may result in a more or less severe hyperbilirubinemia. In this study, we report the cloning and characterization of the transcriptional regulation of the mouse UGT1A1 gene. Primary-structure analysis of the mouse Thymidine Adevice promoter revealed marked differences with its human homolog. First, the mouse promoter lacks the highly polymorphic thymidine/adenine repeat occurring in the human promoter, which has been associated with some forms of hyperbilirubinemia. Second, an L1 transposon element, which is absent in the human promoter, is found 480 bp upstream of the transcription start site in mouse. Using the electromobility shift and DNase I footprinting experiments, we have identified a hepatocyte nuclear factor 1-binding site in the mouse UGT1A1 promoter that confers responsiveness to both factors HNF1alpha and HNF1beta in HEK293 cells. Furthermore, we show that this element, which is conserved in the human promoter, also confers strong HNF1 responsiveness to the human UGT1A1 gene. Together, these results provide evidence for a major regulatory function of this liver-enriched transcription factor in UGT1A1 activity in both rodents and human.
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Affiliation(s)
- P Bernard
- Institut de Biologie Animale, Bâtiment de Biologie, Université de Lausanne, Lausanne, Switzerland
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33
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Ikushiro S, Emi Y, Kimura S, Iyanagi T. Chemical modification of rat hepatic microsomes with N-ethylmaleimide results in inactivation of both UDP-N-acetylglucosamine-dependent stimulation of glucuronidation and UDP-glucuronic acid uptake. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1428:388-96. [PMID: 10434058 DOI: 10.1016/s0304-4165(99)00066-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Chemical modification of rat hepatic microsomes with N-ethylmaleimide (NEM) resulted in inactivation of UDP-N-acetylglucosamine (UDP-GlcNAc)-dependent stimulation of glucuronidation of p-nitrophenol. Inactivation kinetics and pH dependence were in agreement with the modification of a single sulfhydryl group. NEM also inactivated the uptake of UDP-glucuronic acid (UDP-GlcUA) but not UDP-glucose. With various sulfhydryl-modifying reagents, the inactivation of UDP-GlcUA uptake was linked to that of glucuronidation. UDP-GlcUA protected against NEM-sensitive inactivation of both UDP-GlcNAc-dependent stimulation of glucuronidation and UDP-GlcUA uptake, suggesting that the sulfhydryl group is located within or near the UDP-GlcUA binding site of the microsomal protein involved in the stimulation. Using microsomes labeled with biotin-conjugated maleimide and immunopurification with anti-peptide antibody against UDP-glucuronosyltransferase family 1 (UGT1) isozymes, immunopurified UGT1s were found to be labeled with the maleimide and UDP-GlcUA protected against the labeling as it did with the NEM-sensitive inactivation. These data suggest the involvement of a sulfhydryl residue of microsomal protein in the UDP-GlcNAc-dependent stimulation mechanism via the stimulation of UDP-GlcUA uptake into microsomal vesicles.
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Affiliation(s)
- S Ikushiro
- Department of Life Science, Faculty of Science, Himeji Institute of Technology, Harima Science Garden City, Hyogo 678-1297, Japan.
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Zucker SD, Goessling W, Hoppin AG. Unconjugated bilirubin exhibits spontaneous diffusion through model lipid bilayers and native hepatocyte membranes. J Biol Chem 1999; 274:10852-62. [PMID: 10196162 DOI: 10.1074/jbc.274.16.10852] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The liver is responsible for the clearance and metabolism of unconjugated bilirubin, the hydrophobic end-product of heme catabolism. Although several putative bilirubin transporters have been described, it has been alternatively proposed that bilirubin enters the hepatocyte by passive diffusion through the plasma membrane. In order to elucidate the mechanism of bilirubin uptake, we measured the rate of bilirubin transmembrane diffusion (flip-flop) using stopped-flow fluorescence techniques. Unconjugated bilirubin rapidly diffuses through model phosphatidylcholine vesicles, with a first-order rate constant of 5.3 s-1 (t(1)/(2) = 130 ms). The flip-flop rate is independent of membrane cholesterol content, phospholipid acyl saturation, and lipid packing, consistent with thermodynamic analyses demonstrating minimal steric constraint to bilirubin transmembrane diffusion. The coincident decrease in pH of the entrapped vesicle volume supports a mechanism whereby the bilirubin molecule crosses the lipid bilayer as the uncharged diacid. Transport of bilirubin by native rat hepatocyte membranes exhibits kinetics comparable with that in model vesicles, suggesting that unconjugated bilirubin crosses cellular membranes by passive diffusion through the hydrophobic lipid core. In contrast, there is no demonstrable flip-flop of bilirubin diglucuronide or bilirubin ditaurate in phospholipid vesicles, yet these compounds rapidly traverse isolated rat hepatocyte membranes, confirming the presence of a facilitated uptake system(s) for hydrophilic bilirubin conjugates.
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Affiliation(s)
- S D Zucker
- Division of Digestive Diseases, University of Cincinnati Medical Center, Cincinnati, Ohio 45267-0595, USA
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Spicer AP, Kaback LA, Smith TJ, Seldin MF. Molecular cloning and characterization of the human and mouse UDP-glucose dehydrogenase genes. J Biol Chem 1998; 273:25117-24. [PMID: 9737970 DOI: 10.1074/jbc.273.39.25117] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The enzyme UDP-glucose dehydrogenase (Udpgdh) (EC 1.1.1.22) converts UDP-glucose to UDP-glucuronate, a critical component of the glycosaminoglycans, hyaluronan, chondroitin sulfate, and heparan sulfate. Although Udpgdh is a comparatively well characterized enzyme, no vertebrate genes encoding this enzyme have been reported to date. We report the cloning and characterization of the human and mouse UDP-glucose dehydrogenase genes. Mouse and human cDNAs predicted proteins of 493 and 494 amino acids, 24-25 residues longer at their carboxyl termini than the previously reported bovine Udpgdh sequence. The mouse Ugdh gene is composed of 10 exons, spanning 15 kilobases. Northern analyses indicated widespread expression of the gene in embryo and adult. Through interspecific backcross analyses, we localized the Ugdh gene to mouse chromosome 5 at approximately 39 centimorgans, suggesting that the human UGDH gene is localized to chromosome 4p13-15. Results from Southern analyses strongly suggest that Udpgdh is encoded by a single gene in the mouse. Transfection of mouse Ugdh expression vectors led to an increase in detectable Udpgdh activity in mammalian cells. Preliminary expression studies indicated that proinflammatory cytokines, such as interleukin 1beta, can substantially increase the expression of human UGDH in cultured human fibroblasts, suggesting that glycosaminoglycan biosynthesis may be partly regulated by the availability of activated UDP-glucuronate, as determined by relative Udpgdh expression levels.
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Affiliation(s)
- A P Spicer
- Rowe Program in Human Genetics and Molecular Medicine, Department of Biological Chemistry, School of Medicine, Tupper Hall, University of California, Davis, California 95616, USA.
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36
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Ishiyama S, Fuse A, Kuzu H, Igarashi Y, Urayama M, Tsukamoto M. Altered biliary bilirubin profile in patients with persistent hyperbilirubinaemia after hepatic resection: analysis of bile bilirubin subfractions by high-performance liquid chromatography. J Gastroenterol Hepatol 1998; 13:709-14. [PMID: 9715422 DOI: 10.1111/j.1440-1746.1998.tb00718.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Subfractions of bilirubin in bile, obtained via biliary drainage tubes from 23 patients who had undergone radical surgery for bile duct cancer, were analysed by high-performance liquid chromatography for 14 days after surgery. Five principal conjugated bilirubins were resolved: bilirubin diglucuronide (BDG); bilirubin monoglucuronide monoglucoside (BGG); bilirubin monoglucuronide monoxyloside (BGX); and two isomers of bilirubin monoglucuronide. After surgery, depression in concentration of BDG and elevation of BGG and BGX were found. These alterations were of higher magnitude in patients who had undergone hepatectomy, and especially prolonged in patients with hyperbilirubinaemia. These results suggest that the alteration in proportions of bilirubin conjugates might be a cause of hyperbilirubinaemia after hepatectomy.
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Affiliation(s)
- S Ishiyama
- First Department of Surgery, Yamagata University, School of Medicine, Japan
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37
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Meech R, Mackenzie PI. Structure and function of uridine diphosphate glucuronosyltransferases. Clin Exp Pharmacol Physiol 1997; 24:907-15. [PMID: 9406655 DOI: 10.1111/j.1440-1681.1997.tb02718.x] [Citation(s) in RCA: 156] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1. The uridine diphosphate (UDP)-glucuronosyltransferases (UGT) are a family of enzymes that catalyse the covalent addition of glucuronic acid to a wide range of lipophilic chemicals. They play a major role in the detoxification of many exogenous and endogenous compounds by generating products that are more polar and, thus, more readily excreted in bile or urine. 2. Inherited deficiencies in UGT forms are deleterious, as exemplified by the debilitating effects of hyperbilirubinaemia and neurotoxicity in subjects with mutations in the enzyme that converts bilirubin to its more polar glucuronide. 3. The UGT protein can be conceptually divided into two domains with the amino-terminal half of the protein demonstrating greater sequence divergence between isoforms. This region apparently determines aglycone specificity. The aglycone binding site is presumed to be a 'loose' fit, as many structurally diverse substrates can be bound by the same UGT isoform. The carboxyl-terminal half, which is more conserved in sequence between different isoforms, is believed to contain a binding site for the cosubstrate UDP glucuronic acid (UDPGA). 4. Uridine diphosphate glucuronosyltransferase is localized to the endoplasmic reticulum (ER) and spans the membrane with a type I topology. The putative transmembrane domain is located near the carboxyl terminus of the protein such that only a small portion of the protein resides in the cytosol. This cytosolic tail is believed to contain an ER-targeting signal. The major portion of the protein is located in the ER lumen, including the proposed substrate-binding domains and the catalytic site. 5. The microsomal membrane impedes the access of UDPGA to the active site, resulting in latency of UGT activity in intact ER-derived microsomes. Active transport of UDPGA is believed to occur in hepatocytes, but the transport system has not been fully characterized. Uridine diphosphate glucuronosyltransferase activity is also highly lipid dependent and the enzyme may contain regions of membrane association in addition to the transmembrane domain.
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Affiliation(s)
- R Meech
- Department of Clinical Pharmacology, Flinders University of South Australia, Australia
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38
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Sturgill MG, Lambert GH. Xenobiotic-induced hepatotoxicity: mechanisms of liver injury and methods of monitoring hepatic function. Clin Chem 1997. [DOI: 10.1093/clinchem/43.8.1512] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
AbstractXenobiotic-induced liver injury is a clinically important etiology of hepatic disease that, if not recognized, can lead to hepatic failure. In this article we discuss the mechanisms of xenobiotic-induced liver injury, various factors that can alter the risk and severity of injury, the clinical and laboratory manifestations of injury, and the methods used to detect the presence of injury and (or) functioning liver mass.
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Affiliation(s)
- Marc G Sturgill
- Department of Pharmacy Practice and Administration, Rutgers University College of Pharmacy, PO Box 789 William Levine Hall, Piscataway, NJ 08855-0789
- Division of Pediatric Pharmacology and Toxicology, University of Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School, 681 Frelinghuysen Rd., PO Box 1179, Piscataway, NJ 08855-1179
| | - George H Lambert
- Division of Pediatric Pharmacology and Toxicology, University of Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School, 681 Frelinghuysen Rd., PO Box 1179, Piscataway, NJ 08855-1179
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39
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Debinski HS, Lee CS, Dhillon AP, Mackenzie P, Rhode J, Desmond PV. UDP-glucuronosyltransferase in Gilbert's syndrome. Pathology 1996; 28:238-41. [PMID: 8912353 DOI: 10.1080/00313029600169064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The diagnosis of Gilbert's syndrome, a condition characterised by mild jaundice related to chronic unconjugated hyperbilirubinemia, is often presumptive and the pathogenesis is incompletely understood. It would be of interest to develop an immunohistochemical staining method to confirm a diagnosis of Gilbert's syndrome. To this end liver tissues from ten patients with a presumed diagnosis of Gilbert's syndrome and six normal controls were examined by immunohistochemistry with polyclonal antibodies raised to UDP-glucuronosyltransferase (UGT). All subjects had normal liver biopsies by hemotoxylin and eosin staining. In normal human liver specific staining for UGT was seen diffusely in all hepatocytes of the hepatic lobule with zone 3 accentuation. There was a reduction of immunostaining throughout the hepatic lobule in all specimens from patients with Gilbert's syndrome and faint residual staining was seen in zone 3. This thus proved a useful method to confirm a clinical diagnosis of Gilbert's syndrome. Raising monospecific antibodies to UGT may give an insight into polypmorphisms of phase II drug metabolism. Bosma et al.* have recently provided evidence from in vitro studies that subjects with Gilbert's syndrome have a putative defect in the promoter region of the gene encoding UDP-glucuronosyltransferase 1, resulting in reduced transcription. These studies have yet to be confirmed from human biopsy specimens and the possibility of second mutations in intronic sequences affecting the stability of UDP-glucuronosyltransferase 1 m RNA are being explored. *Bosma PJ, Chowdhury JR, Bakker C et al. The genetic basis of the reduced expression of bilirubin UDP-glucuronosyltransferase 1 in Gilbert's syndrome. N Engl J Med 1995; 333: 1171-5.
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Affiliation(s)
- H S Debinski
- Department of Gastroenterology, St Vincent's Hospital, Melbourne, Vic
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40
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Seppen J, Steenken E, Lindhout D, Bosma PJ, Elferink RP. A mutation which disrupts the hydrophobic core of the signal peptide of bilirubin UDP-glucuronosyltransferase, an endoplasmic reticulum membrane protein, causes Crigler-Najjar type II. FEBS Lett 1996; 390:294-8. [PMID: 8706880 DOI: 10.1016/0014-5793(96)00677-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Crigler-Najjar (CN) disease is caused by a deficiency of the hepatic enzyme, bilirubin UDP-glucuronosyltransferase (B-UGT). We have found two CN type II patients, who were homozygous for a leucine to arginine transition at position 15 of B-UGT1. This mutation is expected to disrupt the hydrophobic core of the signal peptide of B-UGT1. Wild type and mutant B-UGT cDNAs were transfected in COS cells. Mutant and wild type mRNA were formed in equal amounts. The mutant protein was expressed with 0.5% efficiency, as compared to wild type. Mutant and wild type mRNAs were translated in vitro. Wild type transferase is processed by microsomes, no processing of the mutant protein was observed.
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Affiliation(s)
- J Seppen
- Department of Gastrointestinal and Liver Diseases, Academic Medical Centre, Amsterdam, The Netherlands.
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41
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Debinski HS, Mackenzie PI, Lee CS, Mashford ML, Danks JA, Tephly TR, Green M, Desmond PV. UDP glucuronosyltransferase in the cirrhotic rat liver. J Gastroenterol Hepatol 1996; 11:373-9. [PMID: 8713705 DOI: 10.1111/j.1440-1746.1996.tb01386.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In patients with cirrhosis, the elimination of drugs metabolized by glucuronidation is relatively preserved, in comparison with the metabolism of drugs by oxidation. This study explores this phenomenon at a molecular level. In cirrhotic rat livers the content of UDP-glucuronosyltransferase (UGT) was examined by immunohistochemistry and immunoblotting using three antibodies: (i) a polyclonal antibody directed against a broad number of UGT isoforms from both family 1 and family 2; (ii) a family 2-specific antibody; and a (iii) family 1-specific antibody. The steady state mRNA level of UGT of a family 2 isoform was also detected by northern blot analysis. The results demonstrate normal or increased UGT protein by immunohistochemistry and immunoblot in cirrhotic livers compared with controls. This was accompanied by increased steady state mRNA encoding the UGT isoform UGT2B1. In contrast, an isoform of cytochrome P450 (CYP2C11) was reduced markedly in both immunohistochemical staining and immunoblot analysis. These results suggest that in cirrhosis there is a comparative increase or at least a maintenance of UGT enzyme content and that this most likely occurs at a pretranslational level.
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Affiliation(s)
- H S Debinski
- Department of Gastroenterology, St Vincent's Hospital, Fitzroy, Victoria, Australia
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42
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Bánhegyi G, Braun L, Marcolongo P, Csala M, Fulceri R, Mandl J, Benedetti A. Evidence for an UDP-glucuronic acid/phenol glucuronide antiport in rat liver microsomal vesicles. Biochem J 1996; 315 ( Pt 1):171-6. [PMID: 8670103 PMCID: PMC1217167 DOI: 10.1042/bj3150171] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The transport of glucuronides synthesized in the luminal compartment of the endoplasmic reticulum by UDP-glucuronosyltransferase isoenzymes was studied in rat liver microsomal vesicles. Microsomal vesicles were loaded with p-nitrophenol glucuronide (5 mM), phenolphthalein glucuronide or UDP-glucuronic acid, by a freeze-thawing method. In was shown that: (i) the loading procedure resulted in millimolar intravesicular concentrations of the different loading compounds; (ii) addition of UDP-glucuronic acid (5 mM) to the vesicles released both intravesicular glucuronides within 1 min; (iii) glucuronides stimulated the release of UDP-glucuronic acid from UDP acid-loaded microsomal vesicles; (iv) trans-stimulation of UDP-glucuronic acid entry by loading of microsomal vesicles with p-nitrophenol glucuronide, phenolphthalein glucuronide, UDP-glucuronic acid and UDP-N-acetyl-glucosamine almost completely abolished the latency of UDP-glucuronosyltransferase, although mannose 6-phosphatase latency remained unaltered; (v) the loading compounds by themselves did not stimulate UDP-glucuronosyltransferase activity. This study indicates that glucuronides synthesized in the lumen of endoplasmic reticulum can leave by an antiport, which concurrently transports USP-glucuronic acid into the lumen of the endoplasmic reticulum.
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Affiliation(s)
- G Bánhegyi
- 1st Institute of Biochemistry, Semmelweis Medical University, Budapest, Hungary
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43
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Seppen J, Tada K, Hellwig S, Bakker CT, Prasad VR, Roy Chowdhury N, Roy Chowdhury J, Bosma PJ, Oude Elferink RP. Bilirubin glucuronidation by intact Gunn rat fibroblasts expressing bilirubin UDP-glucuronosyltransferase. Biochem J 1996; 314 ( Pt 2):477-83. [PMID: 8670060 PMCID: PMC1217075 DOI: 10.1042/bj3140477] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Crigler-Najjar (CN) disease is an inherited disorder of bilirubin metabolism. The disease is caused by a deficiency of the hepatic enzyme bilirubin UDP-glucuronosyltransferase (B-UGT). Patients with CN disease have high serum levels of the toxic compound, unconjugated bilirubin. The only defect in bilirubin metabolism of CN patients is the absence of B-UGT activity. The transplantation of cells able to glucuronidate bilirubin should therefore lower serum bilirubin levels. The Gunn rat is the animal model of CN disease. Primary Gunn rat fibroblasts (GURF) were transduced with a recombinant retrovirus, capable of transferring B-UGT cDNA. A cell line was obtained expressing B-UGT at a level comparable to hepatocytes. Bilirubin added to the culture medium of these cells was glucuronidated and excreted. The B-UGT activities of transduced GURF and freshly isolated Wistar hepatocytes were compared at different bilirubin concentrations. The specific B-UGT activities of these two cell types were comparable when physiological bilirubin concentrations (5-10 microM) were present in the culture media. At higher bilirubin concentrations (20-80 microM) the hepatocytes were more active than the transduced GURF. We conclude that with the addition of only one enzyme (B-UGT) fibroblasts can perform the complete set of reactions necessary for bilirubin glucuronidation. The difference in B-UGT activity between transduced GURF and hepatocytes at 20-80 microM bilirubin can be explained by lower UDP-glucuronic acid and glutathione S-transferase levels in GURF. Our findings also indicate that these cells could be used to develop extrahepatic gene therapy for CN disease.
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Affiliation(s)
- J Seppen
- Department of Gastrointestinal and Liver Disease, Academic Medical Centre, Amsterdam, The Netherlands
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44
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Mulder GJ. Polymorphism in drug conjugation in man: is it a factor of concern in drug toxicity or efficacy? Eur J Pharm Sci 1995. [DOI: 10.1016/0928-0987(94)00066-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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45
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Güldütuna S, Langenbeck U, Bock KW, Sieg A, Leuschner U. Crigler-Najjar syndrome type II. New observation of possible autosomal recessive inheritance. Dig Dis Sci 1995; 40:28-32. [PMID: 7821116 DOI: 10.1007/bf02063937] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The inheritance of Crigler-Najjar syndrome type II (CNS II) is still unclear. Both autosomal dominant transmission with variable penetrance and autosomal recessive transmission have been reported. We describe the diagnosis of CNS II in an adult patient with unconjugated serum bilirubin levels up to 19.6 mg/dl and no detectable activity of bilirubin UDP-glucuronosyltransferase in the liver biopsy. Serum bilirubin levels decreased markedly on phenobarbital treatment. The parents of our patient are first cousins. The mother and three of the patient's five sibs were jaundiced within a few days of birth. Our patient and her jaundiced siblings have 11 children, all healthy and anicteric. We conclude from these data that the inheritance of this very rare disease follows an autosomal recessive pattern, with pseudodominance in this family.
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Affiliation(s)
- S Güldütuna
- Abt. für Gastroenterologie, Johann Wolfgang Goethe-Universität, Frankfurt/M, Germany
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46
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Boelsterli UA, Zimmerman HJ, Kretz-Rommel A. Idiosyncratic liver toxicity of nonsteroidal antiinflammatory drugs: molecular mechanisms and pathology. Crit Rev Toxicol 1995; 25:207-35. [PMID: 7576152 DOI: 10.3109/10408449509089888] [Citation(s) in RCA: 135] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This review explores the clinical hepatic pathology associated with the use of nonsteroidal antiinflammatory drugs (NSAIDs), possible cellular and molecular mechanisms of injury, and future challenges. NSAIDs comprise a group of widely used compounds that have been associated with rare adverse reactions in the liver, including fulminant hepatitis and cholestasis. These reactions are idiosyncratic, mostly independent of the dose administered, and host-dependent. The mechanisms responsible for the initiation and perpetuation of NSAID-induced hepatotoxicity remain poorly understood and have been largely inferred from clinical manifestation. A mounting body of evidence, however, indicates that many acidic NSAIDs are metabolized to reactive acyl glucuronides that can form covalent adducts with plasma proteins and hepatocellular proteins. In hepatocytes cocultured with lymphocytes, these NSAID-altered proteins can become antigenic. Thus, long-lived, drug-altered proteins may act as immunogens and produce cytotoxic T-cell-mediated or antibody-dependent, cell-mediated toxicity in susceptible patients. Alternatively, individual abnormalities in metabolism or disposition of some NSAIDs may lead to the formation or accumulation of toxic metabolites. Additional work with transgenic animal models is needed to permit better understanding of the general and specific risk factors involved in the pathogenesis of the idiosyncratic liver injuries related to NSAIDs and other drugs.
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Affiliation(s)
- U A Boelsterli
- Institute of Toxicology, Swiss Federal Institute of Technology, Schwerzenbach
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47
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Seppen J, Bosma PJ, Goldhoorn BG, Bakker CT, Chowdhury JR, Chowdhury NR, Jansen PL, Oude Elferink RP. Discrimination between Crigler-Najjar type I and II by expression of mutant bilirubin uridine diphosphate-glucuronosyltransferase. J Clin Invest 1994; 94:2385-91. [PMID: 7989595 PMCID: PMC330068 DOI: 10.1172/jci117604] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Crigler-Najjar (CN) disease is classified into two subtypes, type I and II. The molecular basis for the difference between these types is not well understood. Several mutations in the bilirubin UDP-glucuronosyl-transferase (B-UGT) gene of six CN type I and two CN type II patients were identified. Recombinant cDNAs containing these mutations were expressed in COS cells. B-UGT activity was measured using HPLC and the amount of expressed protein was quantitated using a sandwich ELISA. This enabled us to determine the specific activities of the expressed enzymes. All type I patients examined had mutations in the B-UGT1 gene that lead to completely inactive enzymes. The mutations in the B-UGT1 gene of patients with CN type II only partially inactivated the enzyme. At saturating concentrations of bilirubin (75 microM) CN type II patient A had 4.4 +/- 2% residual activity and CN type II patient B had 38 +/- 2% residual activity. Kinetic constants for the glucuronidation of bilirubin were determined. The affinities for bilirubin of B-UGT1 expressed in COS cells and B-UGT from human liver microsomes were similar with Km of 5.1 +/- 0.9 microM and 7.9 +/- 5.3 microM, respectively. B-UGT1 from patient B had a tenfold decreased affinity for bilirubin, Km = 56 +/- 23 microM. At physiological concentrations of bilirubin both type II patients will have a strongly reduced conjugation capacity, whereas type I patients have no B-UGT activity. We conclude that CN type I is caused by a complete absence of functional B-UGT and that in CN type II B-UGT activity is reduced.
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Affiliation(s)
- J Seppen
- Department of Gastrointestinal and Liver Diseases, Academic Medical Centre, Amsterdam, The Netherlands
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48
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Radominska A, Berg C, Treat S, Little JM, Lester R, Gollan JL, Drake RR. Characterization of UDP-glucuronic acid transport in rat liver microsomal vesicles with photoaffinity analogs. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1195:63-70. [PMID: 7918567 DOI: 10.1016/0005-2736(94)90010-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The endoplasmic reticulum (ER) of rat liver contains several well characterized UDP-glucuronosyltransferases (UGTs), membrane-bound proteins of 50-54 kDa, and also less well identified UDP-glucosyltransferases, with nucleotide binding sites located on the lumenal surface. There is evidence that the substrates for these enzymes, UDP-glucuronic acid (UDP-GlcUA) and UDP-glucose (UDP-Glc), biosynthesized in the cytosol, are transported into the lumen of the ER via unknown mechanisms, the characteristics of which are poorly defined. A new approach for the study of the transport process has been devised using two active-site directed photoaffinity analogs, [beta-32P]5-azido-UDP-GlcUA and [beta-32P]5-azido-UDP-Glc. Photoincorporation of these probes into the lumenally oriented UGTs of intact rat liver microsomal vesicles was used as an indicator of transport. In intact vesicles, [32P]5N3UDP-GlcUA was efficiently incorporated into UGTs in a time, temperature and concentration dependent manner. In contrast, [32P]5N3UDP-Glc apparently was not transported effectively; maximal photolabeling of the 50-54 kDa proteins by this probe was dependent on detergent disruption of the vesicles. Vesicular uptake of and subsequent photolabeling of the 50-54 kDa proteins by [32P]5N3UDP-GlcUA were inhibited by UDP-GlcUA and 5N3UDP-GlcUA while UDP-Glc, 5N3UDP-Glc, UDP-xylose and UDP-N-acetylglucosamine were less inhibitory, suggesting a high degree of specificity for the uptake/photolabeling process. The anionic transport inhibitors DIDS and SITS inhibited [32P]5N3UDP-GlcUA photoincorporation into UGTs in intact vesicles, but also inhibited photolabeling of these and other enzymes in detergent disrupted vesicles. These data suggest the presence in rat liver microsomal vesicles of a specific, carrier-mediated transport process for UDP-GlcUA which is distinct from the mechanism of UDP-Glc transport.
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Affiliation(s)
- A Radominska
- Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock 72205
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49
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Münzel PA, Brück M, Bock KW. Tissue-specific constitutive and inducible expression of rat phenol UDP-glucuronosyltransferase. Biochem Pharmacol 1994; 47:1445-8. [PMID: 8185651 DOI: 10.1016/0006-2952(94)90345-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To investigate constitutive and inducible expression of rat phenol UDP-glucuronosyltransferase (UGT1A1) in liver and extrahepatic tissues, a selective cDNA probe for its unique exon 1 was utilized. 6-Hydroxychrysene was used as a functional probe of UGT1A1 activity. Constitutive expression of UGT1A1 was low in liver, but high in kidney, testis, epididymis and ovary. After treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 10 micrograms/kg for 7 days) the UGT1A1 mRNA level was markedly increased in liver (ca. 10-fold), and only moderately enhanced (up to 2-fold) in extrahepatic tissues where constitutive enzyme expression was high. UGT activity toward 6-hydroxychrysene was strongly inducible in liver (ca. 9-fold) and only moderately inducible in extrahepatic tissues (up to 2-fold). The results suggest complex tissue-specific regulation of UGT1A1 including positive and negative transcriptional factors and marked inducibility by TCDD in liver.
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Affiliation(s)
- P A Münzel
- Institute of Toxicology, University of Tübingen, Germany
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50
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Radominska A, Paul P, Treat S, Towbin H, Pratt C, Little J, Magdalou J, Lester R, Drake R. Photoaffinity labeling for evaluation of uridinyl analogs as specific inhibitors of rat liver microsomal UDP-glucuronosyltransferases. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1205:336-45. [PMID: 8155717 DOI: 10.1016/0167-4838(94)90253-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The UDP-glucuronosyltransferases (UGT) involved in glucuronidation of endogenous and exogenous toxic compounds transfer the glucuronic acid residue from UDP-glucuronic acid (UDP-GlcUA), to various acceptor groups. A series of compounds that contain N-acyl phenylaminoalcohol derivatives linked to uridine or isopropylideneuridine were tested as UGT inhibitors. The potency of these inhibitors was determined by studying their effect on the photoaffinity labeling of rat liver microsomal UGTs by two photoaffinity probes, [beta-32P]5-azido-UDP-glucuronic acid (5N3UDP-GlcUA) and [beta-32P]5-azido-UDP-glucose (5N3UDP-Glc) and on the enzymatic formation of the two glucuronide conjugates (3-O- and carboxyl-specific) of lithocholic acid. All but one of the compounds tested proved to have an inhibitory effect on UGTs, both in the photoaffinity labeling system and in the enzymatic glucuronidation assay. In the photoaffinity labeling system, the inhibitors containing the isopropylidene moiety were less effective than their unprotected derivatives; however, the protected forms were, with one exception, more potent inhibitors of enzymatic activity. The photoaffinity labeling of UGTs with [beta-32P]5N3UDP-Glc was more susceptible to inhibition by all derivatives than that with [beta-32P]5N3UDP-GlcUA. The effect of one inhibitor, PP50B, on the two enzymatic activities involved in LA glucuronidation was extensively tested. A double-reciprocal plot suggested a competitive inhibition for UDP-GlcUA with an apparent Ki of 35 microM for LA 3-O-glucuronide formation and 94 microM for the carboxyl-linked glucuronide of the same substrate.
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Affiliation(s)
- A Radominska
- Department of Internal Medicine, University of Arkansas for Medical Sciences, Little Rock 72204
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