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Tang L, Platek ME, Yao S, Till C, Goodman PJ, Tangen CM, Wu Y, Platz EA, Neuhouser ML, Stanczyk FZ, Reichardt JKV, Santella RM, Hsing A, Figg WD, Lippman SM, Thompson IM, Ambrosone CB. Associations between polymorphisms in genes related to estrogen metabolism and function and prostate cancer risk: results from the Prostate Cancer Prevention Trial. Carcinogenesis 2018; 39:125-133. [PMID: 29228205 DOI: 10.1093/carcin/bgx144] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/05/2017] [Indexed: 11/12/2022] Open
Abstract
Substantial preclinical data suggest estrogen's carcinogenic role in prostate cancer development; however, epidemiological evidence based on circulating estrogen levels is largely null. Compared with circulating estrogen, the intraprostatic estrogen milieu may play a more important role in prostate carcinogenesis. Using a nested case-control design in the Prostate Cancer Prevention Trial (PCPT), we examined associations of genetic variants of genes that are involved in estrogen synthesis, metabolism and function with prostate cancer risk. A total of 25 potentially functional single nucleotide polymorphisms (SNPs) in 13 genes (PGR, ESR1, ESR2, CYP17A1, HSD17B1, CYP19A1, CYP1A1, CYP1B1, COMT, UGT1A6, UGT1A10, UGT2B7, UGT2B15) were examined in whites only. Controls (n = 1380) were frequency matched to cases on age, PCPT treatment arm, and family history (n = 1506). Logistic regression models adjusted for age and family history were used to estimate odds ratios (OR) and 95% confidence intervals (CI) separately in the placebo and finasteride arms. SNPs associated with prostate cancer risk differed by treatment arm. The associations appeared to be modified by circulating estrogen and androgen levels. CYP19A1 was the only gene harboring SNPs that were significantly associated with risk in both the placebo and finasteride arms. Haplotype analysis with all three CYP19A1 SNPs genotyped (rs700518, rs2445765, rs700519) showed that risk-allele haplotypes are associated with the increased prostate cancer risk in both arms when comparing with the non-risk allele haplotype. In conclusion, associations between SNPs in estrogen-related genes and prostate cancer risk are complex and may be modified by circulating hormone levels and finasteride treatment.
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Affiliation(s)
- Li Tang
- Department of Cancer Prevention & Control, Roswell Park Cancer Institute, Buffalo, NY, USA
| | - Mary E Platek
- Department of Cancer Prevention & Control, Roswell Park Cancer Institute, Buffalo, NY, USA
| | - Song Yao
- Department of Cancer Prevention & Control, Roswell Park Cancer Institute, Buffalo, NY, USA
| | - Cathee Till
- SWOG Statistical Center, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Phyllis J Goodman
- SWOG Statistical Center, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Catherine M Tangen
- SWOG Statistical Center, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Yue Wu
- Department of Urology, Roswell Park Cancer Institute, Buffalo, NY, USA
| | - Elizabeth A Platz
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Marian L Neuhouser
- Department of Epidemiology, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Frank Z Stanczyk
- Department of Obstetrics & Gynecology, University of Southern California, Los Angeles, CA, USA
| | | | - Regina M Santella
- Environmental Health Sciences, Columbia University, New York, NY, USA
| | - Ann Hsing
- Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, CA, USA
| | - William D Figg
- Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Scott M Lippman
- Cancer Research and Care, UC San Diego Moores Cancer Center, La Jolla, CA, USA
| | - Ian M Thompson
- Department of Urology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Christine B Ambrosone
- Department of Cancer Prevention & Control, Roswell Park Cancer Institute, Buffalo, NY, USA
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2
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Tripathi SP, Bhadauriya A, Patil A, Sangamwar AT. Substrate selectivity of human intestinal UDP-glucuronosyltransferases (UGTs): in silico and in vitro insights. Drug Metab Rev 2013; 45:231-52. [PMID: 23461702 DOI: 10.3109/03602532.2013.767345] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The current drug development process aims to produce safe, effective drugs within a reasonable time and at a reasonable cost. Phase II metabolism (glucuronidation) can affect drug action and pharmacokinetics to a considerable extent and so its studies and prediction at initial stages of drug development are very imperative. Extensive glucuronidation is an obstacle to oral bioavailability because the first-pass glucuronidation [or premature clearance by UDP-glucuronosyltransferases (UGTs)] of orally administered agents frequently results in poor oral bioavailability and lack of efficacy. Modeling of new chemical entities/drugs for UGTs and their kinetic data can be useful in understanding the binding patterns to be used in the design of better molecules. This review concentrates on first-pass glucuronidation by intestinal UGTs, including their topology, expression profile, and pharmacogenomics. In addition, recent advances are discussed with respect to substrate selectivity at the binding pocket, structural requirements, and mechanism of enzyme actions.
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Affiliation(s)
- Satya Prakash Tripathi
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER), Punjab, India
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3
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Korprasertthaworn P, Rowland A, Lewis BC, Mackenzie PI, Yoovathaworn K, Miners JO. Effects of amino acid substitutions at positions 33 and 37 on UDP-glucuronosyltransferase 1A9 (UGT1A9) activity and substrate selectivity. Biochem Pharmacol 2012; 84:1511-21. [DOI: 10.1016/j.bcp.2012.08.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 08/29/2012] [Accepted: 08/29/2012] [Indexed: 10/27/2022]
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4
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Bratton SM, Mosher CM, Khallouki F, Finel M, Court MH, Moran JH, Radominska-Pandya A. Analysis of R- and S-hydroxywarfarin glucuronidation catalyzed by human liver microsomes and recombinant UDP-glucuronosyltransferases. J Pharmacol Exp Ther 2011; 340:46-55. [PMID: 21972237 DOI: 10.1124/jpet.111.184721] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Coumadin (R-, S-warfarin) is a challenging drug to accurately dose, both initially and for maintenance, because of its narrow therapeutic range and wide interpatient variability and is typically administered as a racemic (Rac) mixture, which complicates the biotransformation pathways. The goal of the current work was to identify the human UDP-glucuronosyltransferases (UGTs) involved in the glucuronidation of the separated R- and S-enantiomers of 6-, 7-, and 8-hydroxywarfarin and the possible interactions between these enantiomers. The kinetic and inhibition constants for human recombinant 1A family UGTs toward these separated enantiomers have been assessed using high-performance liquid chromatography (HPLC)-UV-visible analysis, and product confirmations have been made using HPLC-mass spectrometry/mass spectrometry. We found that separated R- and S-enantiomers of 6-, 7-, and 8-hydroxywarfarin demonstrate significantly different glucuronidation kinetics and can be mutually inhibitory. In some cases significant substrate inhibition was observed, as shown by K(m), V(max), and K(i), comparisons. In particular, UGT1A1 and extrahepatic UGT1A10 have significantly higher capacities than other isoforms for S-7-hydroxywarfarin and R-7-hydroxywarfarin glucuronidation, respectively. Activity data generated using a set of well characterized human liver microsomes supported the recombinant enzyme data, suggesting an important (although not exclusive) role for UGT1A1 in glucuronidation of the main warfarin metabolites, including Rac-6- and 7-hydroxywarfarin and their R- and S-enantiomers in the liver. This is the first demonstration that the R- and S-enantiomers of hydroxywarfarins are glucuronidated, with significantly different enzymatic affinity and capacity, and supports the importance of UGT1A1 as the major hepatic isoform involved.
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Affiliation(s)
- Stacie M Bratton
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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5
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Latli B, Hrapchak M, Seetharama R, Krishnamurthy D, Senanayake CH. Chemical synthesis of allyl-[13C6]-glucuronate. J Labelled Comp Radiopharm 2011. [DOI: 10.1002/jlcr.1875] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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6
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Phenotype prediction of nonsynonymous single nucleotide polymorphisms in human phase II drug/xenobiotic metabolizing enzymes: perspectives on molecular evolution. SCIENCE CHINA-LIFE SCIENCES 2010; 53:1252-62. [DOI: 10.1007/s11427-010-4062-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2010] [Accepted: 05/27/2010] [Indexed: 12/18/2022]
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7
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Itäaho K, Laakkonen L, Finel M. How many and which amino acids are responsible for the large activity differences between the highly homologous UDP-glucuronosyltransferases (UGT) 1A9 and UGT1A10? Drug Metab Dispos 2010; 38:687-96. [PMID: 20089735 DOI: 10.1124/dmd.109.031229] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The amino acid sequences of the human UDP-glucuronosyltransferases (UGTs) 1A9 and 1A10 are 93% identical, yet there are large differences in their activity and substrate selectivity. For example, the regioselectivity in propranolol glucuronidation, the regioselectivity in dobutamine glucuronidation, and the glucuronidation rate of alpha- and beta-estradiol differ greatly between UGT1A9 and UGT1A10. To identify the residue responsible for the activity differences, we divided the N-terminal half of the two UGTs into five comparable segments by inserting four unique restriction sites at identical positions in both genes and constructing chimeras in which segments of UGT1A9 were individually replaced by the corresponding segments from UGT1A10. Activity analyses of the resulting mutants, 910A [1A10((1-83))/1A9((84-285))], 910B [1A9((1-83))/1A10((84-147))/1A9((148-285))], 910C [1A9((1-147))/1A10((148-181))/1A9((182-285))], 910D [1A9((1-181))/1A10((182-235))/1A9((236-285))], and 910E [1A9((1-235))/1A10((236-285))] indicated that more than one residue is responsible for the differences between UGT1A9 and UGT1A10. We next prepared four double chimeras, in which two of the above UGT1A9 segments were replaced simultaneously by the corresponding UGT1A10 segments. However, none of the double chimeras glucuronidated either estradiol, propranolol, or dobutamine at rates that resembled those of UGT1A10. On the other hand, studying the kinetics of 1-naphthol glucuronidation yielded more focused results, indicating that residues within segment B (84-147) contribute directly to the K(m) value for this substrate. Further mutagenesis and activity assays suggested that Phe117 of UGT1A9 participates in 1-naphthol binding. In addition, it appears that residues within segment C of the N-terminal domain, mainly at positions 152 and 169, contribute to the higher glucuronidation rates of UGT1A10.
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8
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Di YM, Chan E, Wei MQ, Liu JP, Zhou SF. Prediction of deleterious non-synonymous single-nucleotide polymorphisms of human uridine diphosphate glucuronosyltransferase genes. AAPS JOURNAL 2009; 11:469-80. [PMID: 19572200 DOI: 10.1208/s12248-009-9126-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Accepted: 06/15/2009] [Indexed: 01/15/2023]
Abstract
UDP glucuronosyltransferases (UGTs) are an important class of Phase II enzymes involved in the metabolism and detoxification of numerous xenobiotics including therapeutic drugs and endogenous compounds (e.g. bilirubin). To date, there are 21 human UGT genes identified, and most of them contain single-nucleotide polymorphisms (SNPs). Non-synonymous SNPs (nsSNPs) of the human UGT genes may cause absent or reduced enzyme activity and polymorphisms of UGT have been found to be closely related to altered drug clearance and/or drug response, hyperbilirubinemia, Gilbert's syndrome, and Crigler-Najjar syndrome. However, it is unlikely to study the functional impact of all identified nsSNPs in humans using laboratory approach due to its giant number. We have investigated the potential for bioinformatics approach for the prediction of phenotype based on known nsSNPs. We have identified a total of 248 nsSNPs from human UGT genes. The two algorithms tools, sorting intolerant from tolerant (SIFT) and polymorphism phenotyping (PolyPhen), were used to predict the impact of these nsSNPs on protein function. SIFT classified 35.5% of the UGT nsSNPs as "deleterious"; while PolyPhen identified 46.0% of the UGT nsSNPs as "potentially damaging" and "damaging". The results from the two algorithms were highly associated. Among 63 functionally characterized nsSNPs in the UGTs, 24 showed altered enzyme expression/activities and 45 were associated with disease susceptibility. SIFT and Polyphen had a correct prediction rate of 57.1% and 66.7%, respectively. These findings demonstrate the potential use of bioinformatics techniques to predict genotype-phenotype relationships which may constitute the basis for future functional studies.
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Affiliation(s)
- Yuan Ming Di
- Discipline of Chinese Medicine, School of Health Sciences, RMIT University, Bundoora, Melbourne, Victoria, Australia
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9
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Kerdpin O, Mackenzie PI, Bowalgaha K, Finel M, Miners JO. Influence of N-terminal domain histidine and proline residues on the substrate selectivities of human UDP-glucuronosyltransferase 1A1, 1A6, 1A9, 2B7, and 2B10. Drug Metab Dispos 2009; 37:1948-55. [PMID: 19487247 DOI: 10.1124/dmd.109.028225] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
An N-terminal domain histidine [corresponding to position 39 of UDP-glucuronosyltransferase (UGT) 1A1] is conserved in all UGT1A and UGT2B subfamily proteins except UGT1A4 (Pro-40) and UGT2B10 (Leu-34). Unlike most UGT1A and UGT2B xenobiotic-metabolizing enzymes, UGT1A4 and UGT2B10 lack the ability to glucuronidate 4-methylumbelliferone (4MU) and 1-naphthol (1NP), both planar phenols, and naproxen (a carboxylic acid). However, only UGT1A4 glucuronidates the tertiary amines lamotrigine (LTG) and trifluoperazine (TFP). In this study, we sought to elucidate the influence of specific N-terminal histidine and proline residues on UGT enzyme substrate selectivity. The conserved N-terminal domain histidine of UGT1A1, UGT1A6, UGT1A9, and UGT2B7 was mutated to proline and leucine 34 of UGT2B10 was substituted with histidine, and the capacity of the wild-type and mutant proteins to glucuronidate 4MU, 1NP, LTG, TFP, and naproxen was characterized. Whereas UGT1A1(H39P), UGT1A6(H38P), and UGT1A9(H37P) lacked the ability to metabolize 4MU, 1NP, and naproxen, all glucuronidated LTG. K(m) values for UGT1A1(H39P) and UGT1A9(H37P) were 774 and 3812 microM, respectively, compared with 1579 microM for UGT1A4. UGT1A1(H39P) also glucuronidated TFP with a V(max)/K(m) value comparable to that of UGT1A4. In contrast to the wild-type enzyme, UGT2B10(L34H) glucuronidated 4MU and 1NP with respective K(m) values of 260 and 118 microM. UGT2B7(H35P) lacked activity toward all substrates. The data confirm a pivotal role for an N-terminal domain proline in the glucuronidation of the tertiary amines LTG and TFP by UGT1A subfamily proteins, whereas glucuronidation reactions involving proton abstraction generally, although not invariably, require a histidine at the equivalent position in both UGT1A and UGT2B enzymes.
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Affiliation(s)
- Oranun Kerdpin
- Department of Clinical Pharmacology, Flinders University School of Medicine, Flinders Medical Centre, Bedford Park, SA 5042, Australia
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10
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Strassburg CP, Kalthoff S, Ehmer U. Variability and function of family 1 uridine-5'-diphosphate glucuronosyltransferases (UGT1A). Crit Rev Clin Lab Sci 2009; 45:485-530. [PMID: 19003600 DOI: 10.1080/10408360802374624] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The substrate spectrum of human UDP-glucuronosyltransferase 1A (UGT1A) proteins includes the glucuronidation of non-steroidal anti-inflammatory drugs, anticonvulsants, chemotherapeutics, steroid hormones, bile acids, and bilirubin. The unique genetic organization of the human UGT1A gene locus, and an increasing number of functionally relevant genetic variants define tissue specificity as well as a broad range of interindividual variabilities of glucuronidation. Genetic UGT1A variability has been conserved throughout the protein's evolution and shows ethnic diversity. It is the biochemical and genetic basis for clinical phenotypes such as Gilbert's syndrome and Crigler-Najjar's disease as well as for the potential for severe, unwanted drug side effects such as in irinotecan treatment. UGT1A variants influence the metabolic effects of xenobiotic exposure and therefore have been linked to cancer risk. Detailed knowledge of the organization, function, and pharmacogenetics of the human UGT1A gene locus is likely to significantly contribute to the improvement of drug safety and efficacy as well as to the provision of steps toward the goal of individualized drug therapy and disease risk prediction.
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Affiliation(s)
- Christian P Strassburg
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany.
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11
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Argikar UA, Iwuchukwu OF, Nagar S. Update on tools for evaluation of uridine diphosphoglucuronosyltransferase polymorphisms. Expert Opin Drug Metab Toxicol 2008; 4:879-94. [DOI: 10.1517/17425255.4.7.879] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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12
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Amino acid positions 69-132 of UGT1A9 are involved in the C-glucuronidation of phenylbutazone. Arch Biochem Biophys 2008; 478:75-80. [PMID: 18602884 DOI: 10.1016/j.abb.2008.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 06/12/2008] [Accepted: 06/17/2008] [Indexed: 11/20/2022]
Abstract
Phenylbutazone (PB) is known to be biotransformed to its O- and C-glucuronide. Recently, we reported that PB C-glucuronide formation is catalyzed by UGT1A9. Interestingly, despite UGT1A8 sharing high amino acid sequence identity with UGT1A9, UGT1A8 had no PB C-glucuronidating activity. In the present study, we constructed eight UGT1A9/UGT1A8 chimeras and evaluated which region is important for PB C-glucuronide formation. All of the chimeras and UGT1A8 and UGT1A9 had 7-hydroxy-(4-trifluoromethyl)coumarin (HFC) O-glucuronidating activity. The K(m) values for HFC glucuronidation of UGT1A8, UGT1A9 and their chimeras were divided into two types, UGT1A8 type (high K(m)) and UGT1A9 type (low K(m)), and these types were determined according to whether their amino acids at positions 69-132 were those of UGT1A8 or UGT1A9. Likewise, PB O-glucuronidating activity was also detected by all of the chimeras, and their K(m) values were divided into two types. On the contrary, PB C-glucuronidating activity was detected by UGT1A9((1-132))/1A8((133-286)), UGT1A9((1-212))/1A8((213-286)), UGT1A8((1-68))/1A9((69-286)), and UGT1A8((1-68))/1A9((69-132))/1A8((133-286)) chimeras. The region 1A9((69-132)) was common among chimeras having PB C-glucuronidating activity. Of interest is that UGT1A9((1-68))/1A8((69-132))/1A9((133-286)) had lost PB C-glucuronidation activity, but retained activities of PB and HFC O-glucuronidation. These results strongly suggested that amino acid positions 69-132 of UGT1A9 are responsible for chemoselectivity for PB and affinity to substrates such as PB and HFC.
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Kubota T, Lewis BC, Elliot DJ, Mackenzie PI, Miners JO. Critical Roles of Residues 36 and 40 in the Phenol and Tertiary Amine Aglycone Substrate Selectivities of UDP-Glucuronosyltransferases 1A3 and 1A4. Mol Pharmacol 2007; 72:1054-62. [PMID: 17636046 DOI: 10.1124/mol.107.037952] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Despite high sequence identity, UGT1A3 and UGT1A4 differ in terms of substrate selectivity. UGT1A3 glucuronidates the planar phenols 1-naphthol (1-NP) and 4-methylumbelliferone (4-MU), whereas UGT1A4 converts the tertiary amines lamotrigine (LTG) and trifluoperazine (TFP) to quaternary ammonium glucuronides. Residues 45 to 154 (which incorporate 21 of the 35 amino acid differences) and 45 to 535 were exchanged between UGT1A3 and UGT1A4 to generate UGT1A3-4((45-535)), UGT1A3-4((45-154))-3, UGT1A4-3((45-535)), and UGT1A4-3((45-154))-4 hybrid proteins. Although differences in kinetic parameters were observed between the parent enzymes and chimeras, UGT1A4-3((45-535)) and UGT1A4-3((45-154))-4 [but not UGT1A3-4((45-535)) and UGT1A3-4((45-154))-3] retained the capacity to glucuronidate LTG and TFP. Likewise, UGT1A3-4((45-535)) and UGT1A3-4((45-154))-3 retained the capacity to glucuronidate 1-NP and 4-MU, but UGT1A4-3((45-535)) and UGT1A4-3((45-154))-4 exhibited low or absent activity. Within the first 44 residues, UGT1A3 and UGT1A4 differ in sequence at positions 36 and 40. "Reciprocal" mutagenesis was performed to generate the UGT1A3(I36T), UGT1A3(H40P), UGT1A4(T36I), and UGT1A4 (P40H) mutants. The T36I and P40H mutations in UGT1A4 reduced in vitro clearances for LTG and TFP glucuronidation by >90%. Conversely, the I36T and H40P mutations in UGT1A3 reduced the in vitro clearances for 1-NP and 4-MU glucuronidation by >90%. Introduction of the single H40P mutation in UGT1A3 conferred LTG and TFP glucuronidation, whereas the single T36I mutation in UGT1A4 conferred 1-NP and 4-MU glucuronidation. Thus, residues 36 and 40 of UGT1A3 and UGT1A4 are pivotal for the respective selectivities of these enzymes toward planar phenols and tertiary amines, although other regions of the proteins influence binding affinity and/or turnover.
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Affiliation(s)
- Takahiro Kubota
- Department of Clinical Pharmacology, Flinders Medical Centre, Bedford Park, SA 5042, Australia.
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Owens IS, Basu NK, Banerjee R. UDP-glucuronosyltransferases: gene structures of UGT1 and UGT2 families. Methods Enzymol 2005; 400:1-22. [PMID: 16399340 DOI: 10.1016/s0076-6879(05)00001-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
In human, rat, and mice, a UGT1 complex locus provides for developmental-, inducer-, and cell-specific synthesis of a family of chemical-detoxifying isozymes, UDP-glucuronosyltransferases, which prevent toxicities, mutagenesis, and/or carcinogenesis. Between 10 and 14 first exons with individual promoter elements are tandemly arrayed upstream of 4 shared exons so as to synthesize independently as many overlapping primary transcripts. RNA splice sites allow a lead exon to join the common exons to generate mRNAs with unique 5' ends, but common 3' ends. Intra- and interspecies comparisons of amino acid sequences encoded by first exons show an evolutionary continuum; also, recognizable bilirubin- and phenol-specific catalytic units are differentially regulated by model compounds, phenobarbital, and/or aromatic hydrocarbons. Whereas UGT1 loci allow minimal changes to achieve new isozymes, a single deleterious mutation in a common exon negatively impacts the arrangement by inactivating the entire family of isozymes compared to an event at independent loci as seen in the UGT2 family. In humans, lethal hyperbilirubinemic Crigler-Najjar type 1 and milder diseases/syndromes are due to deleterious to mildly deleterious mutations in the bilirubin-specific UGT1A1 or a common exon. In addition, the number of TA repeats (N(5-8)) in the UGT1A1 proximal TATA box affects transcriptional rate and, thus, activity. Evidence also shows that polymorphisms in nonbilirubin-specific first exons also impact chemical detoxifications and other diseases.
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Affiliation(s)
- Ida S Owens
- Section on Genetic Disorders of Drug Metabolism, Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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Basu NK, Kole L, Kubota S, Owens IS. RESPONSE TO THE LETTER TO THE EDITOR BY DRS. N. PICARD AND P. MARQUET REGARDING A PUBLICATION: BASU ET AL., DRUG METABOLISM AND DISPOSITION (32:768–773, (2004). Drug Metab Dispos 2004. [DOI: 10.1124/dmd.104.002345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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