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Xue J, Li Q, Wang Y, Yin R, Zhang J. Insight into the structure, oligomerization, and the role in drug resistance of human UDP-glucuronosyltransferases. Arch Toxicol 2025; 99:1153-1165. [PMID: 39812829 DOI: 10.1007/s00204-024-03929-6] [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: 10/12/2024] [Accepted: 11/28/2024] [Indexed: 01/16/2025]
Abstract
Human UDP-glucuronosyltransferases (UGTs) are pivotal phase II metabolic enzymes facilitating the transfer of glucuronic acid from UDP-glucuronic acid (UDPGA) to various substrates. UGTs are classic type I transmembrane glycoproteins, mainly localized in the endoplasmic reticulum (ER) membrane. This review comprehensively explores UGTs, encompassing gene expression, functional characteristics, substrate specificity, and metabolic mechanisms. A recent analysis of C-terminal structures, compared with original data, underscores the pivotal role of α3, α4, and β4 functional domains in selectively recognizing diverse glycosyl donors. Accumulating evidence suggests that UGTs function as homo- and heterodimers, with oligomers likely stabilizing UGTs and modulating their activity. The review sheds light on the implications of UGT oligomerization on substrate glucuronidation and the interplay between protein-protein interaction and glucuronidation activity. UGT-mediated drug resistance, often underestimated, emerges as a clinically relevant form of chemical resistance, with delineated outcomes in tumors and other diseases. This review provides a multifaceted exploration of the physiological significance of UGTs, spanning genetics, proteins, oligomerization, drug resistance, and more, offering insights into their metabolic mechanisms. Understanding interactions between UGT isoforms is crucial for predicting drug-drug interactions, preventing drug toxicity, and enabling precision treatment.
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Affiliation(s)
- Jia Xue
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Qiuyi Li
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Yao Wang
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Ruxi Yin
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Jian Zhang
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu, 610041, China.
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2
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Wang S, Huang W, Li M, Wang N, Liu X, Chen M, Peng X. RpUGT344J7 is involved in the reproduction switch of Rhopalosiphum padi with holocyclic life cycle. INSECT SCIENCE 2024. [PMID: 38282241 DOI: 10.1111/1744-7917.13325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 12/11/2023] [Accepted: 12/13/2023] [Indexed: 01/30/2024]
Abstract
Many aphid species exhibit both cyclical parthenogenesis (CP) and the obligate parthenogenesis (OP) life history, which are genetically determined. In CP aphid lineages, the parthenogenetic individuals can switch from asexual to sexual reproduction quickly in response to environmental factors such as changes in photoperiod and temperature. However, the OP aphid lineages do not undergo sexual reproduction under any conditions. So far, mechanisms underlying the reproduction switch in CP aphids have not been fully elucidated. Rhopalosiphum padi, a serious worldwide insect pest of wheat, has both CP and OP lineages. Uridine diphosphate-glycosyltransferases (UGTs) are enzymes that participate in the metabolic detoxification of xenobiotics. Here, we identified 43 RpUGT genes from R. padi genome and transcriptome sequences, and found that: (1) the UGT content of the CP lineage was significantly higher than that in the OP lineage at the key time points when CP lineage mainly produce virginoparae, gynoparae, and males under inducing condition, while there were no significant difference under normal conditions; (2) RpUGT344J7 gene was highly expressed during the time points when CP lineages produce gynopara and males; (3) the critical time points for CP lineages to produce virginoparaee, gynoparae, and males were affected when the CP lineages were injected with dsRpUGT344J7; (4) the knockdown of RpUGT344J7 caused a significant reduction in the total number of virginoparae, gynoparae, and males in the offspring under inducing condition. The findings contribute to our understanding of the molecular mechanisms underlying the quick shift from asexual to sexual reproduction in aphid species.
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Affiliation(s)
- Suji Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
| | - Wenjie Huang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
| | - Mengtian Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
| | - Ni Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
| | - Xi Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
| | - Maohua Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
| | - Xiong Peng
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Key Laboratory of Integrated Pest Management on the Loess Plateau of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi Province, China
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3
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Xue J, Yin J, Nie J, Jiang H, Zhang H, Zeng S. Heterodimerization of Human UDP-Glucuronosyltransferase 1A9 and UDP-Glucuronosyltransferase 2B7 Alters Their Glucuronidation Activities. Drug Metab Dispos 2023; 51:1499-1507. [PMID: 37643881 DOI: 10.1124/dmd.123.001369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 08/31/2023] Open
Abstract
Human UDP-glucuronosyltransferases (UGTs) play a pivotal role as prominent phase II metabolic enzymes, mediating the glucuronidation of both endobiotics and xenobiotics. Dimerization greatly modulates the enzymatic activities of UGTs. In this study, we examined the influence of three mutations (H35A, H268Y, and N68A/N315A) and four truncations (signal peptide, single transmembrane helix, cytosolic tail, and di-lysine motif) in UGT2B7 on its heterodimerization with wild-type UGT1A9, using a Bac-to-Bac expression system. We employed quantitative fluorescence resonance energy transfer (FRET) techniques and co-immunoprecipitation assays to evaluate the formation of heterodimers between UGT1A9 and UGT2B7 allozymes. Furthermore, we evaluated the glucuronidation activities of the heterodimers using zidovudine and propofol as substrates for UGT2B7 and UGT1A9, respectively. Our findings revealed that the histidine residue at codon 35 was involved in the dimeric interaction, as evidenced by the FRET efficiencies and catalytic activities. Interestingly, the signal peptide and single transmembrane helix domain of UGT2B7 had no impact on the protein-protein interaction. These results provide valuable insights for a comprehensive understanding of UGT1A9/UGT2B7 heterodimer formation and its association with glucuronidation activity. SIGNIFICANCE STATEMENT: Our findings revealed that the H35A mutation in UGT2B7 affected the affinity of protein-protein interaction, leading to discernable variations in fluorescence resonance energy transfer efficiencies and catalytic activity. Furthermore, the signal peptide and single transmembrane helix domain of UGT2B7 did not influence heterodimer formation. These results provide valuable insights into the combined effects of polymorphisms and protein-protein interactions on the catalytic activity of UGT1A9 and UGT2B7, enhancing our understanding of UGT dimerization and its impact on metabolite formation.
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Affiliation(s)
- Jia Xue
- Institute of Drug Metabolism and Pharmaceutical Analysis (J.X., J.Y., J.N., H.J., S.Z.) and Hangzhou Institute of Innovative Medicine, Institute of Pharmacology and Toxicology (H.Z.), Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Pharmacy, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang, China (J.N.); and The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (H.Z.)
| | - Jiayi Yin
- Institute of Drug Metabolism and Pharmaceutical Analysis (J.X., J.Y., J.N., H.J., S.Z.) and Hangzhou Institute of Innovative Medicine, Institute of Pharmacology and Toxicology (H.Z.), Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Pharmacy, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang, China (J.N.); and The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (H.Z.)
| | - Jing Nie
- Institute of Drug Metabolism and Pharmaceutical Analysis (J.X., J.Y., J.N., H.J., S.Z.) and Hangzhou Institute of Innovative Medicine, Institute of Pharmacology and Toxicology (H.Z.), Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Pharmacy, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang, China (J.N.); and The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (H.Z.)
| | - Huidi Jiang
- Institute of Drug Metabolism and Pharmaceutical Analysis (J.X., J.Y., J.N., H.J., S.Z.) and Hangzhou Institute of Innovative Medicine, Institute of Pharmacology and Toxicology (H.Z.), Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Pharmacy, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang, China (J.N.); and The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (H.Z.)
| | - Haitao Zhang
- Institute of Drug Metabolism and Pharmaceutical Analysis (J.X., J.Y., J.N., H.J., S.Z.) and Hangzhou Institute of Innovative Medicine, Institute of Pharmacology and Toxicology (H.Z.), Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Pharmacy, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang, China (J.N.); and The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (H.Z.)
| | - Su Zeng
- Institute of Drug Metabolism and Pharmaceutical Analysis (J.X., J.Y., J.N., H.J., S.Z.) and Hangzhou Institute of Innovative Medicine, Institute of Pharmacology and Toxicology (H.Z.), Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Pharmacy, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang, China (J.N.); and The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (H.Z.)
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Xue J, Zhang H, Zeng S. Integrate thermostabilized fusion protein apocytochrome b562RIL and N-glycosylation mutations: A novel approach to heterologous expression of human UDP-glucuronosyltransferase (UGT) 2B7. Front Pharmacol 2022; 13:965038. [PMID: 36034790 PMCID: PMC9412022 DOI: 10.3389/fphar.2022.965038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/19/2022] [Indexed: 11/15/2022] Open
Abstract
Human UDP-glucuronosyltransferase (UGT) 2B7 is a crucial phase II metabolic enzyme that transfers glucuronic acid from UDP-glucuronic acid (UDPGA) to endobiotic and xenobiotic substrates. Biophysical and biochemical investigations of UGT2B7 are hampered by the challenge of the integral membrane protein purification. This study focused on the expression and purification of recombinant UGT2B7 by optimizing the insertion sites for the thermostabilized fusion protein apocytochrome b562RIL (BRIL) and various mutations to improve the protein yields and homogeneity. Preparation of the recombinant proteins with high purity accelerated the measurement of pharmacokinetic parameters of UGT2B7. The dissociation constants (KD) of two classical substrates (zidovudine and androsterone) and two inhibitors (schisanhenol and hesperetin) of UGT2B7 were determined using the surface plasmon resonance spectroscopy (SPR) for the first time. Using negative-staining transmission electron microscopy (TEM), UGT2B7 protein particles were characterized, which could be useful for further exploring its three-dimensional structure. The methods described in this study could be broadly applied to other UGTs and are expected to provide the basis for the exploration of metabolic enzyme kinetics, the mechanisms of drug metabolisms and drug interactions, changes in pharmacokinetics, and pharmacodynamics studies in vitro.
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Affiliation(s)
- Jia Xue
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Haitao Zhang
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, Hangzhou Institute of Innovative Medicine, Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- *Correspondence: Haitao Zhang, ; Su Zeng,
| | - Su Zeng
- Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- *Correspondence: Haitao Zhang, ; Su Zeng,
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5
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Carvalho Henriques B, Yang EH, Lapetina D, Carr MS, Yavorskyy V, Hague J, Aitchison KJ. How Can Drug Metabolism and Transporter Genetics Inform Psychotropic Prescribing? Front Genet 2020; 11:491895. [PMID: 33363564 PMCID: PMC7753050 DOI: 10.3389/fgene.2020.491895] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 09/25/2020] [Indexed: 12/11/2022] Open
Abstract
Many genetic variants in drug metabolizing enzymes and transporters have been shown to be relevant for treating psychiatric disorders. Associations are strong enough to feature on drug labels and for prescribing guidelines based on such data. A range of commercial tests are available; however, there is variability in included genetic variants, methodology, and interpretation. We herein provide relevant background for understanding clinical associations with specific variants, other factors that are relevant to consider when interpreting such data (such as age, gender, drug-drug interactions), and summarize the data relevant to clinical utility of pharmacogenetic testing in psychiatry and the available prescribing guidelines. We also highlight areas for future research focus in this field.
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Affiliation(s)
| | - Esther H. Yang
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
| | - Diego Lapetina
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
| | - Michael S. Carr
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Vasyl Yavorskyy
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Joshua Hague
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
| | - Katherine J. Aitchison
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
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Miyauchi Y, Kurohara K, Kimura A, Esaki M, Fujimoto K, Hirota Y, Takechi S, Mackenzie PI, Ishii Y, Tanaka Y. The carboxyl-terminal di-lysine motif is essential for catalytic activity of UDP-glucuronosyltransferase 1A9. Drug Metab Pharmacokinet 2020; 35:466-474. [PMID: 32883578 DOI: 10.1016/j.dmpk.2020.07.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 11/25/2022]
Abstract
UDP-Glucuronosyltransferase (UGT) is a type I membrane protein localized to the endoplasmic reticulum (ER). UGT has a di-lysine motif (KKXX/KXKXX) in its cytoplasmic domain, which is defined as an ER retention signal. However, our previous study has revealed that UGT2B7, one of the major UGT isoform in human, localizes to the ER in a manner that is independent of this motif. In this study, we focused on another UGT isoform, UGT1A9, and investigated the role of the di-lysine motif in its ER localization, glucuronidation activity, and homo-oligomer formation. Immunofluorescence microscopy indicated that the cytoplasmic domain of UGT1A9 functioned as an ER retention signal in a chimeric protein with CD4, but UGT1A9 itself could localize to the ER in a di-lysine motif-independent manner. In addition, UGT1A9 formed homo-oligomers in the absence of the motif. However, deletion of the di-lysine motif or substitution of lysines in the motif for alanines, severely impaired glucuronidation activity of UGT1A9. This is the first study that re-defines the cytoplasmic di-lysine motif of UGT as an essential peptide for retaining glucuronidation capacity.
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Affiliation(s)
- Yuu Miyauchi
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan; Laboratory of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, Japan.
| | - Ken Kurohara
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Akane Kimura
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Madoka Esaki
- Laboratory of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, Japan
| | - Keiko Fujimoto
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Yuko Hirota
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Shinji Takechi
- Laboratory of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, Japan
| | - Peter I Mackenzie
- Clinical Pharmacology, College of Medicine and Public Health, Flinders Medical Centre and Flinders University, Adelaide, Australia
| | - Yuji Ishii
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan; Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
| | - Yoshitaka Tanaka
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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Lapetina DL, Yang EH, Henriques BC, Aitchison KJ. Pharmacogenomics and Psychopharmacology. SEMINARS IN CLINICAL PSYCHOPHARMACOLOGY 2020:151-202. [DOI: 10.1017/9781911623465.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2025]
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Smith A, Page BDG, Collier AC, Coughtrie MWH. Homology Modeling of Human Uridine-5'-diphosphate-glucuronosyltransferase 1A6 Reveals Insights into Factors Influencing Substrate and Cosubstrate Binding. ACS OMEGA 2020; 5:6872-6887. [PMID: 32258923 PMCID: PMC7114752 DOI: 10.1021/acsomega.0c00205] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 03/11/2020] [Indexed: 05/05/2023]
Abstract
The elimination of numerous endogenous compounds and xenobiotics via glucuronidation by uridine-5'-diphosphate glycosyltransferase enzymes (UGTs) is an essential process of the body's chemical defense system. UGTs have distinct but overlapping substrate preferences, but the molecular basis for their substrate specificity remains poorly understood. Three-dimensional protein structures can greatly enhance our understanding of the interactions between enzymes and their substrates, but because of the inherent difficulties in purifying and crystallizing integral endoplasmic reticulum membrane proteins, no complete mammalian UGT structure has yet been produced. To address this problem, we have created a homology model of UGT1A6 using I-TASSER to explore, in detail, the interactions of human UGT1A6 with its substrates. Ligands were docked into our model in the presence of the cosubstrate uridine-5'-diphosphate-glucuronic acid, interacting residues were examined, and poses were compared to those cocrystallized with various plant and bacterial glycosyltransferases (GTs). Our model structurally resembles other GTs, and docking experiments replicated many of the expected UGT-substrate interactions. Some bias toward the template structures' protein-substrate interactions and binding preferences was evident.
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Cook I, Asenjo AB, Sosa H, Leyh TS. The Human UGT2B7 Nanodisc. Drug Metab Dispos 2020; 48:198-204. [PMID: 31892527 PMCID: PMC7031764 DOI: 10.1124/dmd.119.089946] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 12/30/2019] [Indexed: 01/01/2023] Open
Abstract
The 20 uridine diphosphate glycosyl-transferases (UGTs) encoded in the human genome form an essential homeostatic network of overlapping catalytic functions that surveil and regulate the activity and clearance of scores of small molecule metabolites. Biochemical and biophysical UGT studies have been hampered by the inability to purify these membrane-bound proteins. Here, using cell-free expression and nanodisc technology, we assemble and purify to homogeneity the first UGT nanodisc-the human UGT2B7•nanodisc. The complex is readily isolated in milligram quantities. It is stable and its initial-rate parameters are identical within error to those associated with UGT2B7 in microsomal preparations (i.e., Supersomes). The high purity of the nanodisc preparation simplifies UGT assays, which allows complexities traditionally associated with microsomal assays (latency and the albumin effect) to be circumvented. Each nanodisc is shown to harbor a single UGT2B7 monomer. The methods described herein should be widely applicable to UGTs, and these findings are expected to set the stage for experimentalists to more freely explore the structure, function, and biology of this important area of phase II metabolism. SIGNIFICANCE STATEMENT: Lack of access to pure, catalytically competent human uridine diphosphate glucuronosyl-transferases (UGTs) has long been an impediment to biochemical and biophysical studies of this disease-relevant enzyme family. Here, we demonstrate this barrier can be removed using nanodisc technology-a human UGT2B7•nanodisc is assembled, purified to homogeneity, and shown to have activity comparable to microsomal UGT2B7.
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Affiliation(s)
- Ian Cook
- Departments of Microbiology and Immunology (I.C., T.S.L.) and Physiology and Biophysics (A.B.A., H.S.), Albert Einstein College of Medicine, New York City, New York
| | - Anna B Asenjo
- Departments of Microbiology and Immunology (I.C., T.S.L.) and Physiology and Biophysics (A.B.A., H.S.), Albert Einstein College of Medicine, New York City, New York
| | - Hernando Sosa
- Departments of Microbiology and Immunology (I.C., T.S.L.) and Physiology and Biophysics (A.B.A., H.S.), Albert Einstein College of Medicine, New York City, New York
| | - Thomas S Leyh
- Departments of Microbiology and Immunology (I.C., T.S.L.) and Physiology and Biophysics (A.B.A., H.S.), Albert Einstein College of Medicine, New York City, New York
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10
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Attwood MM, Schiöth HB. Classification of Trispanins: A Diverse Group of Proteins That Function in Membrane Synthesis and Transport Mechanisms. Front Cell Dev Biol 2020; 7:386. [PMID: 32039202 PMCID: PMC6987440 DOI: 10.3389/fcell.2019.00386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 12/19/2019] [Indexed: 11/13/2022] Open
Abstract
As the structure and functions of proteins are correlated, investigating groups of proteins with the same gross structure may provide important insights about their functional roles. Trispanins, proteins that contain three alpha-helical transmembrane (3TM) regions, have not been previously studied considering their transmembrane features. Our comprehensive identification and classification using bioinformatic methods describe 152 3TM proteins. These proteins are frequently involved in membrane biosynthesis and lipid biogenesis, protein trafficking, catabolic processes, and in particular signal transduction due to the large ionotropic glutamate receptor family. Proteins that localize to intracellular compartments are overrepresented in the dataset in comparison to the entire human transmembrane proteome, and nearly 45% localize specifically to the endoplasmic reticulum (ER). Furthermore, nearly 20% of the trispanins function in lipid metabolic processes and transport, which are also overrepresented. Nearly one-third of trispanins are identified as being targeted by drugs and/or being associated with diseases. A high number of 3TMs have unknown functions and based on this analysis we speculate on the functional involvement of uncharacterized trispanins in relationship to disease or important cellular activities. This first overall study of trispanins provides a unique analysis of a diverse group of membrane proteins.
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Affiliation(s)
- Misty M. Attwood
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Helgi B. Schiöth
- Functional Pharmacology, Department of Neuroscience, Uppsala University, Uppsala, Sweden
- Institute for Translational Medicine and Biotechnology, Sechenov First Moscow State Medical University, Moscow, Russia
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Miyauchi Y, Tanaka Y, Nagata K, Yamazoe Y, Mackenzie PI, Yamada H, Ishii Y. UDP-Glucuronosyltransferase (UGT)-mediated attenuations of cytochrome P450 3A4 activity: UGT isoform-dependent mechanism of suppression. Br J Pharmacol 2019; 177:1077-1089. [PMID: 31660580 DOI: 10.1111/bph.14900] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 09/19/2019] [Accepted: 09/28/2019] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND AND PURPOSE Cytochrome P450 (CYP, P450) 3A4 is involved in the metabolism of 50% of drugs and its catalytic activity in vivo is not explained only by hepatic expression levels. We previously demonstrated that UDP-glucuronosyltransferase (UGT) 2B7 suppressed CYP3A4 activity through an interaction. In the present study, we target UGT1A9 as another candidate modulator of CYP3A4. EXPERIMENTAL APPROACH We prepared co-expressed enzymes using the baculovirus-insect cell expression system and compared CYP3A4 activity in the presence and absence of UGT1A9. Wistar rats were treated with dexamethasone and liver microsomes were used to elucidate the role of CYP3A-UGT1A interactions. KEY RESULTS UGT1A9 and UGT2B7 interacted with and suppressed CYP3A4. Kinetic analyses showed that both of the UGTs significantly reduced Vmax of CYP3A4 activity. In addition, C-terminal truncated mutants of UGT1A9 and UGT2B7 still retained the suppressive capacity. Dexamethasone treatment induced hepatic CYP3As and UGT1As at different magnitudes. Turnover of CYP3A was enhanced about twofold by this treatment. CONCLUSION AND IMPLICATIONS The changes of kinetic parameters suggested that UGT1A9 suppressed CYP3A4 activity with almost the same mechanism as UGT2B7. The luminal domain of UGTs contains the suppressive interaction site(s), whereas the C-terminal domain may contribute to modulating suppression in a UGT isoform-specific manner. CYP3A-UGT1A interaction seemed to be disturbed by dexamethasone treatment and the suppression was partially cancelled. CYP3A4-UGT interactions would help to better understand the causes of inter/intra-individual differences in CYP3A4 activity.
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Affiliation(s)
- Yuu Miyauchi
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.,Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Yoshitaka Tanaka
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Kiyoshi Nagata
- Department of Environmental and Health Science, School of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Yasushi Yamazoe
- Food Safety Commission, Cabinet Office, Government of Japan, Tokyo, Japan
| | - Peter I Mackenzie
- Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, SA, Australia
| | - Hideyuki Yamada
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Yuji Ishii
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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12
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Hu DG, Hulin JUA, Nair PC, Haines AZ, McKinnon RA, Mackenzie PI, Meech R. The UGTome: The expanding diversity of UDP glycosyltransferases and its impact on small molecule metabolism. Pharmacol Ther 2019; 204:107414. [PMID: 31647974 DOI: 10.1016/j.pharmthera.2019.107414] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 09/17/2019] [Indexed: 01/23/2023]
Abstract
The UDP glycosyltransferase (UGT) superfamily of enzymes is responsible for the metabolism and clearance of thousands of lipophilic chemicals including drugs, toxins and endogenous signaling molecules. They provide a protective interface between the organism and its chemical-rich environment, as well as controlling critical signaling pathways to maintain healthy tissue function. UGTs are associated with drug responses and interactions, as well as a wide range of diseases including cancer. The human genome contains 22 UGT genes; however as befitting their exceptionally diverse substrate ranges and biological activities, the output of these UGT genes is functionally diversified by multiple processes including alternative splicing, post-translational modification, homo- and hetero-oligomerization, and interactions with other proteins. All UGT genes are subject to extensive alternative splicing generating variant/truncated UGT proteins with altered functions including the capacity to dominantly modulate/inhibit cognate full-length forms. Heterotypic oligomerization of different UGTs can alter kinetic properties relative to monotypic complexes, and potentially produce novel substrate specificities. Moreover, the recently profiled interactions of UGTs with non-UGT proteins may facilitate coordination between different metabolic processes, as well as providing opportunities for UGTs to engage in novel 'moonlighting' functions. Herein we provide a detailed and comprehensive review of all known modes of UGT functional diversification and propose a UGTome model to describe the resulting expansion of metabolic capacity and its potential to modulate drug/xenobiotic responses and cell behaviours in normal and disease contexts.
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Affiliation(s)
- Dong Gui Hu
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - J Ulie-Ann Hulin
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Pramod C Nair
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Alex Z Haines
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Ross A McKinnon
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Peter I Mackenzie
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia
| | - Robyn Meech
- Department of Clinical Pharmacology and Flinders Cancer Centre, Flinders University College of Medicine and Public Health, Flinders Medical Centre, Bedford Park, South Australia, Australia.
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13
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Recombinant Tk0522, a carbohydrate esterase homologue from Thermococcus kodakarensis, does not require a signal sequence for translocation to periplasmic space in Escherichia coli. Biologia (Bratisl) 2019. [DOI: 10.2478/s11756-019-00243-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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14
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Dmitriev AV, Lagunin AA, Karasev DА, Rudik AV, Pogodin PV, Filimonov DA, Poroikov VV. Prediction of Drug-Drug Interactions Related to Inhibition or Induction of Drug-Metabolizing Enzymes. Curr Top Med Chem 2019; 19:319-336. [PMID: 30674264 DOI: 10.2174/1568026619666190123160406] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/02/2019] [Accepted: 01/07/2019] [Indexed: 02/07/2023]
Abstract
Drug-drug interaction (DDI) is the phenomenon of alteration of the pharmacological activity of a drug(s) when another drug(s) is co-administered in cases of so-called polypharmacy. There are three types of DDIs: pharmacokinetic (PK), pharmacodynamic, and pharmaceutical. PK is the most frequent type of DDI, which often appears as a result of the inhibition or induction of drug-metabolising enzymes (DME). In this review, we summarise in silico methods that may be applied for the prediction of the inhibition or induction of DMEs and describe appropriate computational methods for DDI prediction, showing the current situation and perspectives of these approaches in medicinal and pharmaceutical chemistry. We review sources of information on DDI, which can be used in pharmaceutical investigations and medicinal practice and/or for the creation of computational models. The problem of the inaccuracy and redundancy of these data are discussed. We provide information on the state-of-the-art physiologically- based pharmacokinetic modelling (PBPK) approaches and DME-based in silico methods. In the section on ligand-based methods, we describe pharmacophore models, molecular field analysis, quantitative structure-activity relationships (QSAR), and similarity analysis applied to the prediction of DDI related to the inhibition or induction of DME. In conclusion, we discuss the problems of DDI severity assessment, mention factors that influence severity, and highlight the issues, perspectives and practical using of in silico methods.
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Affiliation(s)
| | - Alexey A Lagunin
- Institute of Biomedical Chemistry, Moscow, Russian Federation.,Pirogov Russian National Research Medical University, Moscow, RussiaN Federation
| | | | | | - Pavel V Pogodin
- Institute of Biomedical Chemistry, Moscow, Russian Federation
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15
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Miyauchi Y, Kimura S, Kimura A, Kurohara K, Hirota Y, Fujimoto K, Mackenzie PI, Tanaka Y, Ishii Y. Investigation of the Endoplasmic Reticulum Localization of UDP-Glucuronosyltransferase 2B7 with Systematic Deletion Mutants. Mol Pharmacol 2019; 95:551-562. [PMID: 30944207 DOI: 10.1124/mol.118.113902] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 03/05/2019] [Indexed: 11/22/2022] Open
Abstract
UDP-Glucuronosyltransferase (UGT) plays an important role in the metabolism of endogenous and exogenous compounds. UGT is a type I membrane protein, and has a dilysine motif (KKXX/KXKXX) in its C-terminal cytoplasmic domain. Although a dilysine motif is defined as an endoplasmic reticulum (ER) retrieval signal, it remains a matter of debate whether this motif functions in the ER localization of UGT. To address this issue, we generated systematic deletion mutants of UGT2B7, a major human isoform, and compared their subcellular localizations with that of an ER marker protein calnexin (CNX), using subcellular fractionation and immunofluorescent microscopy. We found that although the dilysine motif functioned as the ER retention signal in a chimera that replaced the cytoplasmic domain of CD4 with that of UGT2B7, UGT2B7 truncated mutants lacking this motif extensively colocalized with CNX, indicating dilysine motif-independent ER retention of UGT2B7. Moreover, deletion of the C-terminal transmembrane and cytoplasmic domains did not affect ER localization of UGT2B7, suggesting that the signal necessary for ER retention of UGT2B7 is present in its luminal domain. Serial deletions of the luminal domain, however, did not affect the ER retention of the mutants. Further, a cytoplasmic and transmembrane domain-deleted mutant of UGT2B7 was localized to the ER without being secreted. These results suggest that UGT2B7 could localize to the ER without any retention signal, and lead to the conclusion that the static localization of UGT results from lack of a signal for export from the ER.
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Affiliation(s)
- Yuu Miyauchi
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Sora Kimura
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Akane Kimura
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Ken Kurohara
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Yuko Hirota
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Keiko Fujimoto
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Peter I Mackenzie
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Yoshitaka Tanaka
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
| | - Yuji Ishii
- Division of Pharmaceutical Cell Biology, Graduate School of Pharmaceutical Sciences (Y.M., A.K., K.K., Y.H., K.F., Y.T.) and Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences (Y.M., S.K., Y.I.), Kyushu University, Fukuoka, Japan; and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia (P.I.M.)
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16
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Chau N, Kaya L, Lewis BC, Mackenzie PI, Miners JO. Drug and Chemical Glucosidation by Control Supersomes and Membranes from Spodoptera frugiperda (Sf) 9 Cells: Implications for the Apparent Glucuronidation of Xenobiotics by UDP-glucuronosyltransferase 1A5. Drug Metab Dispos 2019; 47:271-278. [PMID: 30541877 DOI: 10.1124/dmd.118.084947] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Accepted: 11/29/2018] [Indexed: 01/13/2023] Open
Abstract
Accumulating evidence indicates that several human UDP-glucuronosyltransferase (UGT) enzymes catalyze both glucuronidation and glucosidation reactions. Baculovirus-infected insect cells [Trichoplusia ni and Spodoptera frugiperda (Sf9)] are used widely for the expression of recombinant human UGT enzymes. Following the observation that control Supersomes (c-SUP) express a native enzyme capable of glucosidating morphine, we characterized the glucosidation of a series of aglycones with a hydroxyl (aliphatic or phenolic), carboxylic acid, or amine functional group by c-SUP and membranes from uninfected Sf9 cells. Although both enzyme sources glucosidated the phenolic substrates investigated, albeit with differing activities, differences were observed in the selectivities of the native UDP-glucosyltransferases toward aliphatic alcohols, carboxylic acids, and amines. For example, zidovudine was solely glucosidated by c-SUP. By contrast, c-SUP lacked activity toward the amines lamotrigine and trifluoperazine and did not form the acyl glucoside of mycophenolic acid, reactions all catalyzed by uninfected Sf9 membranes. Glucosidation intrinsic clearances were high for several substrates, notably 1-hydroxypyrene (∼1400-1900 µl/min⋅mg). The results underscore the importance of including control cell membranes in the investigation of drug and chemical glucosidation by UGT enzymes expressed in T. ni (High-Five) and Sf9 cells. In a coincident study, we observed that UGT1A5 expressed in Sf9, human embryonic kidney 293T, and COS7 cells lacked glucuronidation activity toward prototypic phenolic substrates. However, Sf9 cells expressing UGT1A5 glucosidated 1-hydroxypyrene with UDP-glucuronic acid as the cofactor, presumably due to the presence of UDP-glucose as an impurity. Artifactual glucosidation may explain, at least in part, a previous report of phenolic glucuronidation by UGT1A5.
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Affiliation(s)
- Nuy Chau
- Department of Clinical Pharmacology (N.C., L.K., B.C.L., P.I.M., J.O.M.) and Flinders Centre for Innovation in Cancer (B.C.L., P.I.M., J.O.M.), Flinders University College of Medicine and Public Health, Adelaide, Australia
| | - Leyla Kaya
- Department of Clinical Pharmacology (N.C., L.K., B.C.L., P.I.M., J.O.M.) and Flinders Centre for Innovation in Cancer (B.C.L., P.I.M., J.O.M.), Flinders University College of Medicine and Public Health, Adelaide, Australia
| | - Benjamin C Lewis
- Department of Clinical Pharmacology (N.C., L.K., B.C.L., P.I.M., J.O.M.) and Flinders Centre for Innovation in Cancer (B.C.L., P.I.M., J.O.M.), Flinders University College of Medicine and Public Health, Adelaide, Australia
| | - Peter I Mackenzie
- Department of Clinical Pharmacology (N.C., L.K., B.C.L., P.I.M., J.O.M.) and Flinders Centre for Innovation in Cancer (B.C.L., P.I.M., J.O.M.), Flinders University College of Medicine and Public Health, Adelaide, Australia
| | - John O Miners
- Department of Clinical Pharmacology (N.C., L.K., B.C.L., P.I.M., J.O.M.) and Flinders Centre for Innovation in Cancer (B.C.L., P.I.M., J.O.M.), Flinders University College of Medicine and Public Health, Adelaide, Australia
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17
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Labriet A, Allain EP, Rouleau M, Audet-Delage Y, Villeneuve L, Guillemette C. Post-transcriptional Regulation of UGT2B10 Hepatic Expression and Activity by Alternative Splicing. Drug Metab Dispos 2018; 46:514-524. [PMID: 29438977 PMCID: PMC5894810 DOI: 10.1124/dmd.117.079921] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 01/31/2018] [Indexed: 12/17/2022] Open
Abstract
The detoxification enzyme UDP-glucuronosyltransferase UGT2B10 is specialized in the N-linked glucuronidation of many drugs and xenobiotics. Preferred substrates possess tertiary aliphatic amines and heterocyclic amines, such as tobacco carcinogens and several antidepressants and antipsychotics. We hypothesized that alternative splicing (AS) constitutes a means to regulate steady-state levels of UGT2B10 and enzyme activity. We established the transcriptome of UGT2B10 in normal and tumoral tissues of multiple individuals. The highest expression was in the liver, where 10 AS transcripts represented 50% of the UGT2B10 transcriptome in 50 normal livers and 44 hepatocellular carcinomas. One abundant class of transcripts involves a novel exonic sequence and leads to two alternative (alt.) variants with novel in-frame C termini of 10 or 65 amino acids. Their hepatic expression was highly variable among individuals, correlated with canonical transcript levels, and was 3.5-fold higher in tumors. Evidence for their translation in liver tissues was acquired by mass spectrometry. In cell models, they colocalized with the enzyme and influenced the conjugation of amitriptyline and levomedetomidine by repressing or activating the enzyme (40%-70%; P < 0.01) in a cell context-specific manner. A high turnover rate for the alt. proteins, regulated by the proteasome, was observed in contrast to the more stable UGT2B10 enzyme. Moreover, a drug-induced remodeling of UGT2B10 splicing was demonstrated in the HepaRG hepatic cell model, which favored alt. variants expression over the canonical transcript. Our findings support a significant contribution of AS in the regulation of UGT2B10 expression in the liver with an impact on enzyme activity.
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Affiliation(s)
- Adrien Labriet
- Pharmacogenomics Laboratory, Centre Hospitalier Universitaire de Québec Research Center and Faculty of Pharmacy, Québec, Canada Research Chair in Pharmacogenomics, Université Laval, Québec, Canada
| | - Eric P Allain
- Pharmacogenomics Laboratory, Centre Hospitalier Universitaire de Québec Research Center and Faculty of Pharmacy, Québec, Canada Research Chair in Pharmacogenomics, Université Laval, Québec, Canada
| | - Michèle Rouleau
- Pharmacogenomics Laboratory, Centre Hospitalier Universitaire de Québec Research Center and Faculty of Pharmacy, Québec, Canada Research Chair in Pharmacogenomics, Université Laval, Québec, Canada
| | - Yannick Audet-Delage
- Pharmacogenomics Laboratory, Centre Hospitalier Universitaire de Québec Research Center and Faculty of Pharmacy, Québec, Canada Research Chair in Pharmacogenomics, Université Laval, Québec, Canada
| | - Lyne Villeneuve
- Pharmacogenomics Laboratory, Centre Hospitalier Universitaire de Québec Research Center and Faculty of Pharmacy, Québec, Canada Research Chair in Pharmacogenomics, Université Laval, Québec, Canada
| | - Chantal Guillemette
- Pharmacogenomics Laboratory, Centre Hospitalier Universitaire de Québec Research Center and Faculty of Pharmacy, Québec, Canada Research Chair in Pharmacogenomics, Université Laval, Québec, Canada
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18
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Characterization of a membrane-bound C-glucosyltransferase responsible for carminic acid biosynthesis in Dactylopius coccus Costa. Nat Commun 2017; 8:1987. [PMID: 29215010 PMCID: PMC5719414 DOI: 10.1038/s41467-017-02031-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 11/02/2017] [Indexed: 11/09/2022] Open
Abstract
Carminic acid, a glucosylated anthraquinone found in scale insects like Dactylopius coccus, has since ancient times been used as a red colorant in various applications. Here we show that a membrane-bound C-glucosyltransferase, isolated from D. coccus and designated DcUGT2, catalyzes the glucosylation of flavokermesic acid and kermesic acid into their respective C-glucosides dcII and carminic acid. DcUGT2 is predicted to be a type I integral endoplasmic reticulum (ER) membrane protein, containing a cleavable N-terminal signal peptide and a C-terminal transmembrane helix that anchors the protein to the ER, followed by a short cytoplasmic tail. DcUGT2 is found to be heavily glycosylated. Truncated DcUGT2 proteins synthesized in yeast indicate the presence of an internal ER-targeting signal. The cleavable N-terminal signal peptide is shown to be essential for the activity of DcUGT2, whereas the transmembrane helix/cytoplasmic domains, although important, are not crucial for its catalytic function. Carminic acid is a widely applied red colorant that is still harvested from insects because its biosynthesis is not fully understood. Here, the authors identify and characterize a membrane-bound C-glucosyltransferase catalyzing the final step during carminic acid biosynthesis.
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Liu Y, Coughtrie MWH. Revisiting the Latency of Uridine Diphosphate-Glucuronosyltransferases (UGTs)-How Does the Endoplasmic Reticulum Membrane Influence Their Function? Pharmaceutics 2017; 9:E32. [PMID: 28867809 PMCID: PMC5620573 DOI: 10.3390/pharmaceutics9030032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 08/26/2017] [Accepted: 08/28/2017] [Indexed: 11/18/2022] Open
Abstract
Uridine diphosphate-glucuronosyltransferases (UGTs) are phase 2 conjugation enzymes mainly located in the endoplasmic reticulum (ER) of the liver and many other tissues, and can be recovered in artificial ER membrane preparations (microsomes). They catalyze glucuronidation reactions in various aglycone substrates, contributing significantly to the body's chemical defense mechanism. There has been controversy over the last 50 years in the UGT field with respect to the explanation for the phenomenon of latency: full UGT activity revealed by chemical or physical disruption of the microsomal membrane. Because latency can lead to inaccurate measurements of UGT activity in vitro, and subsequent underprediction of drug clearance in vivo, it is important to understand the mechanisms behind this phenomenon. Three major hypotheses have been advanced to explain UGT latency: compartmentation, conformation, and adenine nucleotide inhibition. In this review, we discuss the evidence behind each hypothesis in depth, and suggest some additional studies that may reveal more information on this intriguing phenomenon.
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Affiliation(s)
- Yuejian Liu
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
| | - Michael W H Coughtrie
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
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20
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Dixit VA, Lal LA, Agrawal SR. Recent advances in the prediction of non‐
CYP450
‐mediated drug metabolism. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1323] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Vaibhav A. Dixit
- Department of Pharmaceutical Chemistry, School of Pharmacy & Technology Management (SPTM)Shri Vile Parle Kelavani Mandal's (SVKM's), Narsee Monjee Institute of Management Studies (NMIMS)ShirpurIndia
| | - L. Arun Lal
- Department of Pharmaceutical Chemistry, School of Pharmacy & Technology Management (SPTM)Shri Vile Parle Kelavani Mandal's (SVKM's), Narsee Monjee Institute of Management Studies (NMIMS)ShirpurIndia
| | - Simran R. Agrawal
- Department of Pharmaceutical Chemistry, School of Pharmacy & Technology Management (SPTM)Shri Vile Parle Kelavani Mandal's (SVKM's), Narsee Monjee Institute of Management Studies (NMIMS)ShirpurIndia
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21
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Miyauchi Y, Nagata K, Yamazoe Y, Mackenzie PI, Yamada H, Ishii Y. Suppression of Cytochrome P450 3A4 Function by UDP-Glucuronosyltransferase 2B7 through a Protein-Protein Interaction: Cooperative Roles of the Cytosolic Carboxyl-Terminal Domain and the Luminal Anchoring Region. Mol Pharmacol 2015; 88:800-12. [PMID: 26243732 DOI: 10.1124/mol.115.098582] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 07/31/2015] [Indexed: 12/13/2022] Open
Abstract
There is a large discrepancy between the interindividual difference in the hepatic expression level of cytochrome P450 3A4 (CYP3A4) and that of drug clearance mediated by this enzyme. However, the reason for this discrepancy remains largely unknown. Because CYP3A4 interacts with UDP-glucuronosyltransferase 2B7 (UGT2B7) to alter its function, the reverse regulation is expected to modulate CYP3A4-catalyzed activity. To address this issue, we investigated whether protein-protein interaction between CYP3A4 and UGT2B7 modulates CYP3A4 function. For this purpose, we coexpressed CYP3A4, NADPH-cytochrome P450 reductase, and UGT2B7 using a baculovirus-insect cell system. The activity of CYP3A4 was significantly suppressed by coexpressing UGT2B7, and this suppressive effect was lost when UGT2B7 was replaced with calnexin (CNX). These results strongly suggest that UGT2B7 negatively regulates CYP3A4 activity through a protein-protein interaction. To identify the UGT2B7 domain associated with CYP3A4 suppression we generated 12 mutants including chimeras with CNX. Mutations introduced into the UGT2B7 carboxyl-terminal transmembrane helix caused a loss of the suppressive effect on CYP3A4. Thus, this hydrophobic region is necessary for the suppression of CYP3A4 activity. Replacement of the hydrophilic end of UGT2B7 with that of CNX produced a similar suppressive effect as the native enzyme. The data using chimeric protein demonstrated that the internal membrane-anchoring region of UGT2B7 is also needed for the association with CYP3A4. These data suggest that 1) UGT2B7 suppresses CYP3A4 function, and 2) both hydrophobic domains located near the C terminus and within UGT2B7 are needed for interaction with CYP3A4.
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Affiliation(s)
- Yuu Miyauchi
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan (Y.M., H.Y., Y.I.); Tohoku Pharmaceutical University, Sendai, Japan (K.N.); Food Safety Commission, Cabinet Office, Government of Japan, Tokyo, Japan (Y.Y.); and Department of Clinical Pharmacology, Flinders Medical Center and Flinders University, Adelaide, Australia (P.I.M.)
| | - Kiyoshi Nagata
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan (Y.M., H.Y., Y.I.); Tohoku Pharmaceutical University, Sendai, Japan (K.N.); Food Safety Commission, Cabinet Office, Government of Japan, Tokyo, Japan (Y.Y.); and Department of Clinical Pharmacology, Flinders Medical Center and Flinders University, Adelaide, Australia (P.I.M.)
| | - Yasushi Yamazoe
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan (Y.M., H.Y., Y.I.); Tohoku Pharmaceutical University, Sendai, Japan (K.N.); Food Safety Commission, Cabinet Office, Government of Japan, Tokyo, Japan (Y.Y.); and Department of Clinical Pharmacology, Flinders Medical Center and Flinders University, Adelaide, Australia (P.I.M.)
| | - Peter I Mackenzie
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan (Y.M., H.Y., Y.I.); Tohoku Pharmaceutical University, Sendai, Japan (K.N.); Food Safety Commission, Cabinet Office, Government of Japan, Tokyo, Japan (Y.Y.); and Department of Clinical Pharmacology, Flinders Medical Center and Flinders University, Adelaide, Australia (P.I.M.)
| | - Hideyuki Yamada
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan (Y.M., H.Y., Y.I.); Tohoku Pharmaceutical University, Sendai, Japan (K.N.); Food Safety Commission, Cabinet Office, Government of Japan, Tokyo, Japan (Y.Y.); and Department of Clinical Pharmacology, Flinders Medical Center and Flinders University, Adelaide, Australia (P.I.M.)
| | - Yuji Ishii
- Laboratory of Molecular Life Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan (Y.M., H.Y., Y.I.); Tohoku Pharmaceutical University, Sendai, Japan (K.N.); Food Safety Commission, Cabinet Office, Government of Japan, Tokyo, Japan (Y.Y.); and Department of Clinical Pharmacology, Flinders Medical Center and Flinders University, Adelaide, Australia (P.I.M.)
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22
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Riches Z, Collier AC. Posttranscriptional regulation of uridine diphosphate glucuronosyltransferases. Expert Opin Drug Metab Toxicol 2015; 11:949-65. [PMID: 25797307 DOI: 10.1517/17425255.2015.1028355] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION The uridine diphosphate (UDP)-glucuronosyltransferase (UGT) superfamily of enzymes (EC 2.4.1.17) conjugates glucuronic acid to an aglycone substrate to make them more polar and readily excreted. In general, this reaction terminates the activities of chemicals, drugs and toxins, although occasionally a more active or toxic species is produced. AREAS COVERED In addition to their well-known transcriptional responsiveness, UGTs are also regulated by posttranscriptional mechanisms. Here, the authors review these mechanisms, including latency, modulation of co-substrate accessibility and binding, dimerization and oligomerization, protein-protein interactions, allosteric inhibition and activation, posttranslational structural and functional modifications and developmental switching for UGTs. EXPERT OPINION Posttranscriptional regulation of UGTs has traditionally received less attention than nuclear regulation, in part because mechanisms involving ribosomes and endoplasmic reticula are challenging to investigate. Most promising of the posttranscriptional mechanisms reviewed are likely to be effects on co-substrate (UDP-glucuronic acid) transport and availability and structure-function changes to UGT proteins through, for example, glycosylation and phosphorylation. Although classical biochemistry continues to illuminate many aspects of UGT function, advances in proteomics and structural biology are beginning to assist in the determination of posttranscriptional regulation mechanisms for UGTs.
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Affiliation(s)
- Zoe Riches
- University of British Columbia, Faculty of Pharmaceutical Sciences , 2405 Wesbrook Mall, Vancouver, BC V6T 1Z3 , Canada +1 604 827 2380 ;
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23
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Ziegler K, Tumova S, Kerimi A, Williamson G. Cellular asymmetric catalysis by UDP-glucuronosyltransferase 1A8 shows functional localization to the basolateral plasma membrane. J Biol Chem 2015; 290:7622-33. [PMID: 25586184 DOI: 10.1074/jbc.m114.634428] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
UDP-glucuronosyltransferases (UGTs) are highly expressed in liver, intestine and kidney, and catalyze the glucuronic acid conjugation of both endogenous compounds and xenobiotics. Using recombinant human UGT isoforms, we show that glucuronic acid conjugation of the model substrate, (-)-epicatechin, is catalyzed mainly by UGT1A8 and UGT1A9. In HepG2 cells, pretreatment with polyunsaturated fatty acids increased substrate glucuronidation. In the intestinal Caco-2/HT29-MTX co-culture model, overall relative glucuronidation rates were much higher than in HepG2 cells, and (-)-epicatechin was much more readily conjugated when applied to the basolateral side of the cell monolayer. Under these conditions, 95% of the conjugated product was effluxed back to the site of application, and none of the other phase 2-derived metabolites followed this distribution pattern. HT29-MTX cells contained >1000-fold higher levels of UGT1A8 mRNA than Caco-2 or HepG2 cells. Gene expression of UGT1A8 increased after treatment of cells with docosahexaenoic acid, as did UGT1A protein levels. Immunofluorescence staining and Western blotting showed the presence of UGT1A in the basal and lateral parts of the plasma membrane of HT29-MTX cells. These results suggest that some of the UGT1A8 enzyme is not residing in the endoplasmic reticulum but spans the plasma membrane, resulting in increased accessibility to compounds outside the cell. This facilitates more efficient conjugation of substrate and is additionally coupled with rapid efflux by functionally associated basolateral transporters. This novel molecular strategy allows the cell to carry out conjugation without the xenobiotic entering into the interior of the cell.
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Affiliation(s)
- Kerstin Ziegler
- From the Faculty of Mathematics and Physical Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Sarka Tumova
- From the Faculty of Mathematics and Physical Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Asimina Kerimi
- From the Faculty of Mathematics and Physical Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Gary Williamson
- From the Faculty of Mathematics and Physical Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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24
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Ouzzine M, Gulberti S, Ramalanjaona N, Magdalou J, Fournel-Gigleux S. The UDP-glucuronosyltransferases of the blood-brain barrier: their role in drug metabolism and detoxication. Front Cell Neurosci 2014; 8:349. [PMID: 25389387 PMCID: PMC4211562 DOI: 10.3389/fncel.2014.00349] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/06/2014] [Indexed: 12/12/2022] Open
Abstract
UDP-glucuronosyltransferases (UGTs) form a multigenic family of membrane-bound enzymes expressed in various tissues, including brain. They catalyze the formation of β-D-glucuronides from structurally unrelated substances (drugs, other xenobiotics, as well as endogenous compounds) by the linkage of glucuronic acid from the high energy donor, UDP-α-D-glucuronic acid. In brain, UGTs actively participate to the overall protection of the tissue against the intrusion of potentially harmful lipophilic substances that are metabolized as hydrophilic glucuronides. These metabolites are generally inactive, except for important pharmacologically glucuronides such as morphine-6-glucuronide. UGTs are mainly expressed in endothelial cells and astrocytes of the blood brain barrier (BBB). They are also associated to brain interfaces devoid of BBB, such as circumventricular organ, pineal gland, pituitary gland and neuro-olfactory tissues. Beside their key-role as a detoxication barrier, UGTs play a role in the steady-state of endogenous compounds, like steroids or dopamine (DA) that participate to the function of the brain. UGT isoforms of family 1A, 2A, 2B and 3A are expressed in brain tissues to various levels and are known to present distinct but overlapping substrate specificity. The importance of these enzyme species with regard to the formation of toxic, pharmacologically or physiologically relevant glucuronides in the brain will be discussed.
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Affiliation(s)
- Mohamed Ouzzine
- UMR 7365 CNRS-Université de Lorraine "Ingénierie Moléculaire, Physiopathologie Articulaire" Vandoeuvre-lès-Nancy, France
| | - Sandrine Gulberti
- UMR 7365 CNRS-Université de Lorraine "Ingénierie Moléculaire, Physiopathologie Articulaire" Vandoeuvre-lès-Nancy, France
| | - Nick Ramalanjaona
- UMR 7365 CNRS-Université de Lorraine "Ingénierie Moléculaire, Physiopathologie Articulaire" Vandoeuvre-lès-Nancy, France
| | - Jacques Magdalou
- UMR 7365 CNRS-Université de Lorraine "Ingénierie Moléculaire, Physiopathologie Articulaire" Vandoeuvre-lès-Nancy, France
| | - Sylvie Fournel-Gigleux
- UMR 7365 CNRS-Université de Lorraine "Ingénierie Moléculaire, Physiopathologie Articulaire" Vandoeuvre-lès-Nancy, France
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25
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Ishii Y, Koba H, Kinoshita K, Oizaki T, Iwamoto Y, Takeda S, Miyauchi Y, Nishimura Y, Egoshi N, Taura F, Morimoto S, Ikushiro S, Nagata K, Yamazoe Y, Mackenzie PI, Yamada H. Alteration of the function of the UDP-glucuronosyltransferase 1A subfamily by cytochrome P450 3A4: different susceptibility for UGT isoforms and UGT1A1/7 variants. Drug Metab Dispos 2014; 42:229-38. [PMID: 24255116 DOI: 10.1124/dmd.113.054833] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2025] Open
Abstract
Functional protein-protein interactions between UDP-glucuronosyltransferase (UGT)1A isoforms and cytochrome P450 (CYP)3A4 were studied. To this end, UGT1A-catalyzed glucuronidation was assayed in Sf-9 cells that simultaneously expressed UGT and CYP3A4. In the kinetics of UGT1A6-catalyzed glucuronidation of serotonin, both Michaelis constant (Km) and maximal velocity (Vmax) were increased by CYP3A4. When CYP3A4 was coexpressed with either UGT1A1 or 1A7, the Vmax for the glucuronidation of the irinotecan metabolite (SN-38) was significantly increased. S50 and Km both which are the substrate concentration giving 0.5 Vmax were little affected by simultaneous expression of CYP3A4. This study also examined the catalytic properties of the allelic variants of UGT1A1 and 1A7 and their effects on the interaction with CYP3A4. Although the UGT1A1-catalyzing activity of 4-methylumbelliferone glucuronidation was reduced in its variant, UGT1A1*6, the coexpression of CYP3A4 restored the impaired function to a level comparable with the wild type. Similarly, simultaneous expression of CYP3A4 increased the Vmax of UGT1A7*1 (wild type) and *2 (N129K and R131K), whereas the same was not observed in UGT1A7*3 (N129K, R131K, and W208R). In the kinetics involving different concentrations of UDP-glucuronic acid (UDP-GlcUA), the Km for UDP-GlcUA was significantly higher for UGT1A7*2 and *3 than *1. The Km of UGT1A7*1 and *3 was increased by CYP3A4, whereas *2 did not exhibit any such change. These results suggest that (1) CYP3A4 changes the catalytic function of the UGT1A subfamily in a UGT isoform-specific manner and (2) nonsynonymous mutations in UGT1A7*3 reduce not only the ability of UGT to use UDP-GlcUA but also CYP3A4-mediated enhancement of catalytic activity, whereas CYP3A4 is able to restore the UGT1A1*6 function.
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Affiliation(s)
- Yuji Ishii
- Laboratory of Molecular Life Sciences (Y.Is., H.K., K.K., T.O., Y.Iw., S.T., Y.M., Y.N., N.E., H.Y.) and Laboratory of Medicinal Resource Regulation (F.T., S.M.), Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan; Biotechnology Research Center, Faculty of Engineering, Toyama Prefectural University, Imizu, Toyama, Japan (S.I.); Tohoku Pharmaceutical University, Sendai, Japan (K.N.); Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan (Y.Y.); and Department of Clinical Pharmacology, Flinders Medical Centre and Flinders University, Adelaide, Australia (P.I.M.)
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26
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Wang XL, Hu ZY, You CX, Kong XZ, Shi XP. Subcellular localization and vacuolar targeting of sorbitol dehydrogenase in apple seed. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2013; 210:36-45. [PMID: 23849111 DOI: 10.1016/j.plantsci.2013.04.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/21/2013] [Accepted: 04/24/2013] [Indexed: 06/02/2023]
Abstract
Sorbitol is the primary photosynthate and translocated carbohydrate in fruit trees of the Rosaceae family. NAD(+)-dependent sorbitol dehydrogenase (NAD-SDH, EC 1.1.1.14), which mainly catalyzes the oxidation of sorbitol to fructose, plays a key role in regulating sink strength in apple. In this study, we found that apple NAD-SDH was ubiquitously distributed in epidermis, parenchyma, and vascular bundle in developing cotyledon. NAD-SDH was localized in the cytosol, the membranes of endoplasmic reticulum and vesicles, and the vacuolar lumen in the cotyledon at the middle stage of seed development. In contrast, NAD-SDH was mainly distributed in the protein storage vacuoles in cotyledon at the late stage of seed development. Sequence analysis revealed there is a putative signal peptide (SP), also being predicated to be a transmembrane domain, in the middle of proteins of apple NAD-SDH isoforms. To investigate whether the putative internal SP functions in the vacuolar targeting of NAD-SDH, we analyzed the localization of the SP-deletion mutants of MdSDH5 and MdSDH6 (two NAD-SDH isoforms in apple) by the transient expression system in Arabidopsis protoplasts. MdSDH5 and MdSDH6 were not localized in the vacuoles after their SPs were deleted, suggesting the internal SP functions in the vacuolar targeting of apple NAD-SDH.
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Affiliation(s)
- Xiu-Ling Wang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, China.
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27
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Protein-protein interactions between the bilirubin-conjugating UDP-glucuronosyltransferase UGT1A1 and its shorter isoform 2 regulatory partner derived from alternative splicing. Biochem J 2013; 450:107-14. [PMID: 23148825 DOI: 10.1042/bj20121594] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The oligomerization of UGTs [UDP (uridine diphosphate)-glucuronosyltransferases] modulates their enzyme activities. Recent findings also indicate that glucuronidation is negatively regulated by the formation of inactive oligomeric complexes between UGT1A enzymes [i1 (isoform 1)] and an enzymatically inactive alternatively spliced i2 (isoform 2). In the present paper, we assessed whether deletion of the UGT-interacting domains previously reported to be critical for enzyme function might be involved in i1-i2 interactions. The bilirubin-conjugating UGT1A1 was used as a prototype. We also explored whether intermolecular disulfide bonds are involved in i1-i2 interactions and the potential role of selected cysteine residues. Co-immunoprecipitation assays showed that UGT1A1 lacking the SP (signal peptide) alone or also lacking the transmembrane domain (absent from i2) did not self-interact, but still interacted with i2. The deletion of other N- or C-terminal domains did not compromise i1-i2 complex formation. Under non-reducing conditions, we also observed formation of HMWCs (high-molecular-mass complexes) for cells overexpressing i1 and i2. The presence of UGTs in these complexes was confirmed by MS. Mutation of individual cysteine residues throughout UGT1A1 did not compromise i1-i1 or i1-i2 complex formation. These findings are compatible with the hypothesis that the interaction between i1 and i2 proteins (either transient or stable) involves binding of more than one domain that probably differs from those involved in i1-i1 interactions.
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28
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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: 16] [Impact Index Per Article: 1.3] [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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29
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Nagaraj S, Wong S, Truong K. Parts-based assembly of synthetic transmembrane proteins in mammalian cells. ACS Synth Biol 2012; 1:111-7. [PMID: 23651113 DOI: 10.1021/sb200007r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Transmembrane proteins span cellular membranes such as the plasma membrane and endoplasmic reticulum (ER) membrane to mediate inter- and intracellular interactions. An N-terminal signal peptide and transmembrane helices facilitate recruitment to the ER and integration into the membrane, respectively. Using a parts-based assembly approach in this study, we confirm that the minimum requirement to create a transmembrane protein is indeed only a transmembrane helix (TM). When transfected in mammalian cells, our fusion proteins in the schematic form X-TM-Y were localized to vesicles, the golgi apparatus, the nuclear envelope, or the endoplasmic reticulum, consistent with ER targeting. Further studies to determine orientation showed that X was facing the cytoplasm, and Y the lumen. Lastly, in our fusion proteins with an N-terminal TM, the TM effectively reversed the orientation of X and Y. This knowledge can be applied to the parts-based engineering of synthetic transmembrane proteins with varied functions and biological applications.
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Affiliation(s)
- Seema Nagaraj
- Institute of Biomaterials
and
Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9, Canada
| | - Stanley Wong
- Institute of Biomaterials
and
Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9, Canada
| | - Kevin Truong
- Institute of Biomaterials
and
Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9, Canada
- Edward S. Rogers, Sr. Department
of Electrical and Computer Engineering, University of Toronto, 10 King’s College Circle, Toronto, Ontario,
M5S 3G4, Canada
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30
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Cheng X, Wang H. Multiple targeting motifs direct NRAMP1 into lysosomes. Biochem Biophys Res Commun 2012; 419:578-83. [PMID: 22382021 DOI: 10.1016/j.bbrc.2012.02.078] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 02/12/2012] [Indexed: 11/16/2022]
Abstract
Natural resistance-associated macrophage protein 1 (NRAMP1) containing 548 amino acids (AA) and 12 transmembrane domains (TMDs) is localized in membranes of lysosomes. Our study aimed to investigate the targeting motifs of NRAMP1 by expressing GFP-tagged full-length and truncated NRAMP1 proteins and overlapping with the lysosomal marker Lamp1-RFP in Chinese hamster ovary (CHO) cells. The NH(2)-terminal amino acids 73-140 region including TMD2 was essential for NRAMP1 lysosomal targeting. The AA.263-334 region containing the tyrosine-based motif (327)YAPI(330) targeted NRAMP1 into lysosomes. Additionally, two internal signal peptides AA.451-483 and AA.489-522 were identified as lysosomal targeting motifs. Taken together, NRAMP1 consists of multiple targeting motifs for trafficking into lysosomes.
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Affiliation(s)
- Xiang Cheng
- Department of Animal Biotechnology, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, China
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31
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Vander Heyden AB, Naismith TV, Snapp EL, Hanson PI. Static retention of the lumenal monotopic membrane protein torsinA in the endoplasmic reticulum. EMBO J 2011; 30:3217-31. [PMID: 21785409 DOI: 10.1038/emboj.2011.233] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 06/16/2011] [Indexed: 02/06/2023] Open
Abstract
TorsinA is a membrane-associated enzyme in the endoplasmic reticulum (ER) lumen that is mutated in DYT1 dystonia. How it remains in the ER has been unclear. We report that a hydrophobic N-terminal domain (NTD) directs static retention of torsinA within the ER by excluding it from ER exit sites, as has been previously reported for short transmembrane domains (TMDs). We show that despite the NTD's physicochemical similarity to TMDs, it does not traverse the membrane, defining torsinA as a lumenal monotopic membrane protein and requiring a new paradigm to explain retention. ER retention and membrane association are perturbed by a subset of nonconservative mutations to the NTD, suggesting that a helical structure with defined orientation in the membrane is required. TorsinA preferentially enriches in ER sheets, as might be expected for a lumenal monotopic membrane protein. We propose that the principle of membrane-based protein sorting extends to monotopic membrane proteins, and identify other proteins including the monotopic lumenal enzyme cyclooxygenase 1 (prostaglandin H synthase 1) that share this mechanism of retention with torsinA.
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Affiliation(s)
- Abigail B Vander Heyden
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO, USA
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32
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Juanes MA, Martínez-Garay CA, Igual JC, Bañó MC. Targeting and membrane insertion into the endoplasmic reticulum membrane of Saccharomyces cerevisiae essential protein Rot1. FEMS Yeast Res 2010; 10:639-47. [PMID: 20608986 DOI: 10.1111/j.1567-1364.2010.00653.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Rot1 is an essential yeast protein that has been related to cell wall biosynthesis, actin cytoskeleton dynamics and protein folding. Rot1 is an N-glycosylated protein anchored to the nuclear envelope-endoplasmic reticulum (ER) membrane by a transmembrane domain at its C-terminal end. Rot1 is translocated to the ER by a post-translational mechanism. Here, we investigate the protein domain required to target and translocate Rot1 to the ER membrane. We found that several deletions of the N-terminal region of Rot1 prevented neither membrane targeting nor the insertion of this protein. Interestingly, we obtained the same results when different truncated forms in the C-terminal transmembrane domain were analyzed, suggesting the presence of an internal topogenic element that is capable of translocating Rot1 to the ER. To identify this sequence, we generated a combination of N- and C-terminal deletion mutants of Rot1 and we investigated their insertion into the membrane. The results show that two regions, amino acids 26-60 and 200-228, are involved in the post-translational translocation of Rot1 across the ER membrane.
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Affiliation(s)
- María Angeles Juanes
- Departament de Bioquímica i Biologia Molecular, Universitat de València, València, Spain
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33
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Laakkonen L, Finel M. A molecular model of the human UDP-glucuronosyltransferase 1A1, its membrane orientation, and the interactions between different parts of the enzyme. Mol Pharmacol 2010; 77:931-9. [PMID: 20215562 DOI: 10.1124/mol.109.063289] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The vertebrate UDP-glucuronosyltransferases (UGTs) are membrane-bound enzymes of the endoplasmic reticulum that process both endogenous and exogenous substrates. The human UGTs are well known biologically, but biophysical understanding is scarce, largely because of problems in purification. The one resolved crystal structure covers the C-terminal domain of the human UGT2B7. Here, we present a homology model of the complete monomeric human UGT1A1, the enzyme that catalyzes bilirubin glucuronidation. The enzyme can be seen as composed of four different domains: two large ones, the N- and C-terminal domains, and two small ones, the "envelope" helices and the transmembrane segment that includes the cytoplasmic tail. The hydrophobic core of the N-terminal domain and the two envelope helices that connect the large domains are shown to be structurally well conserved even among distant homologs and can thus be modeled with good certainty according to plant and bacterial structures. We consider alternative solutions for the highly variable N-terminal regions that probably contribute to substrate binding. The bilirubin binding site, known pathological mutations in UGT1A1, and other specific residues have been examined in the context of the model with regard to available experimental data. A putative orientation of the protein relative to the membrane has been derived from the location of predicted N-glycosylation sites. The model presents extensive interactions between the N- and C-terminal domains, the two envelope helices, and the membrane. Together, these interactions could allow for a concerted large-scale conformational change during catalysis.
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Affiliation(s)
- Liisa Laakkonen
- Centre for Drug Research, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
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Magdalou J, Fournel-Gigleux S, Ouzzine M. Insights on membrane topology and structure/function of UDP-glucuronosyltransferases. Drug Metab Rev 2010; 42:159-66. [PMID: 19807219 DOI: 10.3109/03602530903209270] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The main characteristic of uridine diphosphate (UDP)-glucuronosyltransferases is their potency to glucuronidate a large array of structurally unrelated substances with various nucleophilic groups. The activity of these enzymes strongly depends on their tight association to the membrane of the endoplasmic reticulum. In light of recent data, this review is focused on the membrane-assembly process, which is a prerequisite for activity, and on the amino acids that govern substrate recognition and catalysis at the active site. The major implication of the highly variable N-terminal domain of UDP-glucuronosyltransferases in the substrate specificity of these enzymes is highlighted. In the absence of crystal data of the N-terminal domain, multidisciplinary approaches of genetic-/protein-engineering techniques, homology modeling with glycosyltransferases, and quantitative structure-activity relationships allowed us to point out crucial amino acids. On the basis of these results, possible reaction mechanisms for the glucuronidation of xenobiotics, involving histidine and aspartic acid residues, have been built and are discussed.
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Affiliation(s)
- Jacques Magdalou
- UMR 7561 CNRS-Université Henri Poincaré-Nancy-1, Faculté de Médecine, Vandoeuvre-lès-Nancy, France.
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35
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Radominska-Pandya A, Bratton SM, Redinbo MR, Miley MJ. The crystal structure of human UDP-glucuronosyltransferase 2B7 C-terminal end is the first mammalian UGT target to be revealed: the significance for human UGTs from both the 1A and 2B families. Drug Metab Rev 2010; 42:133-44. [PMID: 19821783 DOI: 10.3109/03602530903209049] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Human UDP-glucuronosyltransferases (EC 2.4.1.17) (UGTs) are major phase II metabolism enzymes that detoxify a multitude of endo- and xenobiotics through the covalent addition of a glucuronic acid moiety. UGTs are promiscuous enzymes that regulate the levels of numerous important endobiotics in a range of tissues, and inactivate most therapeutic compounds in concert with phase I enzymes. In spite of the importance of these enzymes, we have only a limited understanding of the molecular mechanisms governing their substrate specificity and catalytic activity. Until recently, no three-dimensional structural information was available for any mammalian UGT. The 1.8-å resolution apo crystal structure of the UDP-glucuronic acid binding domain of human UGT2B7 (2B7CT) is the only structure of a mammalian UGT target determined to date. In this review, we summarize what has been learned about human UGT function from the analysis of this and other related glycosyltransferase (GT) crystal structures.
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Affiliation(s)
- Anna Radominska-Pandya
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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Ishii Y, Takeda S, Yamada H. Modulation of UDP-glucuronosyltransferase activity by protein-protein association. Drug Metab Rev 2010; 42:145-58. [PMID: 19817679 DOI: 10.3109/03602530903208579] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Drug oxidation and conjugation mediated by cytochrome P450 (P450) and UDP-glucuronosyltransferase (UGT) have long been considered to take place separately. However, our recent studies have suggested that CYP3A4 specifically associates with UGT2B7 and alters the regioselectivity of morphine glucuronidation. This observation strongly supports the view that there is functional cooperation between P450 and UGT to facilitate multistep drug metabolism. In recent years, accumulating evidence has suggested an interaction between UGT isoforms or between P450 and UGTs and a change in UGT function by protein-protein association. In this review, we summarize these interactions and discuss their relevance to UGT function.
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Affiliation(s)
- Yuji Ishii
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
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Bellemare J, Rouleau M, Harvey M, Guillemette C. Modulation of the human glucuronosyltransferase UGT1A pathway by splice isoform polypeptides is mediated through protein-protein interactions. J Biol Chem 2009; 285:3600-3607. [PMID: 19996319 DOI: 10.1074/jbc.m109.083139] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This study investigated the molecular mechanisms underlying the regulatory effect of the newly discovered 45-kDa enzymatically inactive UGT1A spliced polypeptides, named isoform i2, upon UGT1A-mediated glucuronidation. Initially, using an inducible system that mimics the relative abundance of isoforms 1 and 2 of UGT1A1 in human tissues, the rates of formation of glucuronides were significantly reduced. We then used a heterologous system constitutively expressing both isoforms i1 and i2 for an in-depth investigation of the presence of spliced i2 on glucuronidation kinetics. UGT1A1, UGT1A7, and UGT1A8 were selected as candidates for these studies. In all cases, co-expression of i1 and i2 in HEK293 cells leads to a significant reduction of the velocity of the glucuronidation reaction without affecting the affinity (K(m) (app)) for all substrates tested and the K(m) for the co-substrate, UDP-glucuronic acid. The data are consistent with a dominant-negative model of inhibition but do not sustain with an UGT1A_i2-mediated inhibition by competitive binding for substrate or the co-substrate. In contrast, the data from the co-immunoprecipitation experiments are indicative of the existence of a mixture homo-oligomeric (i1-i1 or i2-i2) and hetero-oligomeric (i1-i2) complexes in which the i2-i2 and i1-i2 subunits would be inactive. Thus, protein-protein interactions are likely responsible for the inhibition of active UGT1A_i1 by i2 spliced polypeptides. This new regulatory mechanism may alternatively modulate cellular response to endo/xeno stimulus.
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Affiliation(s)
- Judith Bellemare
- From the Pharmacogenomics Laboratory, Centre Hospitalier de l'Université Laval Research Center and Faculty of Pharmacy, Laval University, Québec, Québec G1V 4G2, Canada
| | - Mélanie Rouleau
- From the Pharmacogenomics Laboratory, Centre Hospitalier de l'Université Laval Research Center and Faculty of Pharmacy, Laval University, Québec, Québec G1V 4G2, Canada
| | - Mario Harvey
- From the Pharmacogenomics Laboratory, Centre Hospitalier de l'Université Laval Research Center and Faculty of Pharmacy, Laval University, Québec, Québec G1V 4G2, Canada
| | - Chantal Guillemette
- From the Pharmacogenomics Laboratory, Centre Hospitalier de l'Université Laval Research Center and Faculty of Pharmacy, Laval University, Québec, Québec G1V 4G2, Canada.
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Guillemette C, Lévesque E, Harvey M, Bellemare J, Menard V. UGT genomic diversity: beyond gene duplication. Drug Metab Rev 2009; 42:24-44. [DOI: 10.3109/03602530903210682] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Bock KW, Köhle C. Topological aspects of oligomeric UDP-glucuronosyltransferases in endoplasmic reticulum membranes: Advances and open questions. Biochem Pharmacol 2009; 77:1458-65. [DOI: 10.1016/j.bcp.2008.12.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 12/04/2008] [Accepted: 12/09/2008] [Indexed: 11/24/2022]
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Takeda S, Ishii Y, Iwanaga M, Nurrochmad A, Ito Y, Mackenzie PI, Nagata K, Yamazoe Y, Oguri K, Yamada H. Interaction of cytochrome P450 3A4 and UDP-glucuronosyltransferase 2B7: evidence for protein-protein association and possible involvement of CYP3A4 J-helix in the interaction. Mol Pharmacol 2009; 75:956-64. [PMID: 19158361 DOI: 10.1124/mol.108.052001] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have reported that the protein-protein interaction between UDP-glucuronosyltransferase (UGT) 2B7 and cytochrome P450 3A4 (CYP3A4) alters UGT2B7 function. However, the domain(s) involved in the interaction are largely unknown. To address this issue, we examined in more detail the CYP3A4-UGT2B7 association by means of immunoprecipitation, overlay assay, and cross-linking involving 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. Purified CYP3A4 or glutathione transferase (GST)-tagged CYP3A4 was cross-linked to UGT2B7 in solubilized baculosomes. The formation of the cross-linked complex was detected by immunoblotting using both antibodies against CYP3A4 and UGTs. Although the GST-tagged CYP3A4 containing the region ranging from Tyr25 to Ala503 was cross-linked to UGT2B7, the same did not occur when another construct containing Met145 to His267 was used. This observation was consistent with the result of the overlay assay indicating that CYP3A4 lacking the N-terminal hydrophobic segment retains the ability to associate with UGT2B7, whereas the Met145-to-His267 region loses this capacity. Although the Met145-to-His267 peptide was recognized by one anti-CYP3A4 antibody that has the ability to coimmunoprecipitate UGT2B7, it was not recognized by another antibody incapable of coimmunoprecipitating UGT2B7. The epitope of the latter antibody was mapped to the Leu331-to-Lys342 region, which is located on the J-helix of CYP3A4. Taken together, the results obtained suggest that 1) CYP3A4 and UGT2B7 are a pair of enzymes in proximity to each other and 2) either the Leu331-to-Lys342 domain or the surrounding region plays a role in the interaction with UGT2B7, whereas the hydrophobic Met145-to-His267 region does not contribute to this interaction.
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Affiliation(s)
- Shuso Takeda
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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Hiss JA, Resch E, Schreiner A, Meissner M, Starzinski-Powitz A, Schneider G. Domain organization of long signal peptides of single-pass integral membrane proteins reveals multiple functional capacity. PLoS One 2008; 3:e2767. [PMID: 18648515 PMCID: PMC2447879 DOI: 10.1371/journal.pone.0002767] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 06/25/2008] [Indexed: 01/22/2023] Open
Abstract
Targeting signals direct proteins to their extra - or intracellular destination such as the plasma membrane or cellular organelles. Here we investigated the structure and function of exceptionally long signal peptides encompassing at least 40 amino acid residues. We discovered a two-domain organization (“NtraC model”) in many long signals from vertebrate precursor proteins. Accordingly, long signal peptides may contain an N-terminal domain (N-domain) and a C-terminal domain (C-domain) with different signal or targeting capabilities, separable by a presumably turn-rich transition area (tra). Individual domain functions were probed by cellular targeting experiments with fusion proteins containing parts of the long signal peptide of human membrane protein shrew-1 and secreted alkaline phosphatase as a reporter protein. As predicted, the N-domain of the fusion protein alone was shown to act as a mitochondrial targeting signal, whereas the C-domain alone functions as an export signal. Selective disruption of the transition area in the signal peptide impairs the export efficiency of the reporter protein. Altogether, the results of cellular targeting studies provide a proof-of-principle for our NtraC model and highlight the particular functional importance of the predicted transition area, which critically affects the rate of protein export. In conclusion, the NtraC approach enables the systematic detection and prediction of cryptic targeting signals present in one coherent sequence, and provides a structurally motivated basis for decoding the functional complexity of long protein targeting signals.
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Affiliation(s)
- Jan A. Hiss
- Centre for Membrane Proteomics, Institute of Cell Biology and Neuroscience, Goethe-University, Frankfurt am Main, Germany
| | - Eduard Resch
- Centre for Membrane Proteomics, Institute of Cell Biology and Neuroscience, Goethe-University, Frankfurt am Main, Germany
| | - Alexander Schreiner
- Centre for Membrane Proteomics, Institute of Cell Biology and Neuroscience, Goethe-University, Frankfurt am Main, Germany
| | - Michael Meissner
- Centre for Membrane Proteomics, Institute of Cell Biology and Neuroscience, Goethe-University, Frankfurt am Main, Germany
| | - Anna Starzinski-Powitz
- Centre for Membrane Proteomics, Institute of Cell Biology and Neuroscience, Goethe-University, Frankfurt am Main, Germany
| | - Gisbert Schneider
- Centre for Membrane Proteomics, Institute of Cell Biology and Neuroscience, Goethe-University, Frankfurt am Main, Germany
- * E-mail:
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Genetic diversity at the UGT1 locus is amplified by a novel 3' alternative splicing mechanism leading to nine additional UGT1A proteins that act as regulators of glucuronidation activity. Pharmacogenet Genomics 2008; 17:1077-89. [PMID: 18004212 DOI: 10.1097/fpc.0b013e3282f1f118] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The gene UGT1 encodes phase II detoxification proteins involved in the elimination of small hydrophobic substances of both endogenous and exogenous origin. To date, nine functional UGT1A proteins are known to be produced from a single gene composed of alternative first exons shared with four common exons. Recently, a novel exon (referred to as exon 5b) was identified in the common shared region. RESULTS We now reveal a novel alternative splicing mechanism and demonstrate that the exon 5a and the new exon 5b are alternatively spliced, generating several variant mRNAs and up to nine previously unknown variant UGT1A proteins, referred to as isoforms 2 or i2. Isoform-specific RT-PCR analyses reveal that the alternatively spliced mRNAs are widely distributed in human tissues. Immunoreactive proteins at the predicted molecular weight of approximately 45 kDa were confirmed in microsomes of human tissues using antibodies against UGT1A1 and anti-UGT1A7/8/9/10. Functional enzyme assays demonstrate that i2 proteins containing exon 5b are enzymatically inactive. On the other hand, co-expression experiments of i2 of UGT1A1, UGT1A7, UGT1A8 and UGT1A9 with their classical isoform 1 homologs results in a significant repression (15 to 79%) of UGT1A_i1-mediated drug metabolism. CONCLUSION The UGT1A isoforms 2 act as negative modulators of their isoform 1 homologs in microsome preparations, revealing a new regulatory mechanism of the glucuronidation pathway. Findings further provide the first direct evidence of a novel alternative splicing mechanism at the 3' end of the UGT1 locus that further increases the number of proteins derived from this single gene.
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Li D, Fournel-Gigleux S, Barré L, Mulliert G, Netter P, Magdalou J, Ouzzine M. Identification of aspartic acid and histidine residues mediating the reaction mechanism and the substrate specificity of the human UDP-glucuronosyltransferases 1A. J Biol Chem 2007; 282:36514-24. [PMID: 17956868 DOI: 10.1074/jbc.m703107200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human UDP-glucuronosyltransferase UGT1A6 is the primary phenol-metabolizing UDP-glucuronosyltransferase isoform. It catalyzes the nucleophilic attack of phenolic xenobiotics on UDP-glucuronic acid, leading to the formation of water-soluble glucuronides. The catalytic mechanism proposed for this reaction is an acid-base mechanism that involves an aspartic/glutamic acid and/or histidine residue. Here, we investigated the role of 14 highly conserved aspartic/glutamic acid residues over the entire sequence of human UGT1A6 by site-directed mutagenesis. We showed that except for aspartic residues Asp-150 and Asp-488, the substitution of carboxylic residues by alanine led to active mutants but with decreased enzyme activity and lower affinity for acceptor and/or donor substrate. Further analysis including mutation of the corresponding residue in other UGT1A isoforms suggests that Asp-150 plays a major catalytic role. In this report we also identified a single active site residue important for glucuronidation of phenols and carboxylic acid substrates by UGT1A enzyme family. Replacing Pro-40 of UGT1A4 by histidine expanded the glucuronidation activity of the enzyme to phenolic and carboxylic compounds, therefore, leading to UGT1A3-type isoform in terms of substrate specificity. Conversely, when His-40 residue of UGT1A3 was replaced with proline, the substrate specificity shifted toward that of UGT1A4 with loss of glucuronidation of phenolic substrates. Furthermore, mutation of His-39 residue of UGT1A1 (His-40 in UGT1A4) to proline led to loss of glucuronidation of phenols but not of estrogens. This study provides a step forward to better understand the glucuronidation mechanism and substrate recognition, which is invaluable for a better prediction of drug metabolism and toxicity in human.
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Affiliation(s)
- Dong Li
- UMR 7561, Faculté de Médecine and UMR 7036, Faculté des Sciences, CNRS-Université Henri Poincaré Nancy 1, 54505 Vandoeuvre-lès-Nancy, France
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Samanta K, Kar P, Ghosh B, Chakraborti T, Chakraborti S. Localization of m-calpain and calpastatin and studies of their association in pulmonary smooth muscle endoplasmic reticulum. Biochim Biophys Acta Gen Subj 2007; 1770:1297-307. [PMID: 17656025 DOI: 10.1016/j.bbagen.2007.06.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 06/18/2007] [Accepted: 06/22/2007] [Indexed: 11/25/2022]
Abstract
Calpain and calpastatin have been demonstrated to play many physiological roles in a variety of systems. It, therefore, appears important to study their localization and association in different suborganelles. Using immunoblot studies, we have identified 80 kDa m-calpain in both lumen and membrane of ER isolated from bovine pulmonary artery smooth muscle. Treatment of the ER with Na(2)CO(3) and proteinase K demonstrated that 80 kDa catalytic subunit and 28 kDa regulatory subunit (Rs) of m-calpain, and the 110-kDa and 70-kDa calpastatin (Cs) forms are localized in the cytosolic side of the ER membrane. Coimmunoprecipitation studies revealed that m-calpain is associated with calpastatin in the cytosolic face of the ER membrane. We have also identified m-calpain activity both in the ER membrane and lumen by casein-zymography. The casein-zymogram has also been utilized to demonstrate differential pattern of the effects of reversible and irreversible cysteine protease inhibitors on m-calpain activity. Thus, a potential site of Cs regulation of m-calpain activity is created by positioning Cs, 80 kDa and 28 kDa m-calpain in the cytosolic face of ER membrane. However, such is not the case for the 80-kDa m-calpain found within the lumen of the ER because of the conspicuous absence of 28 kDa Rs of m-calpain and Cs in this locale.
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Affiliation(s)
- Krishna Samanta
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal, India
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Fondeur-Gelinotte M, Lattard V, Gulberti S, Oriol R, Mulliert G, Coughtrie MW, Magdalou J, Netter P, Ouzzine M, Fournel-Gigleux S. Molecular basis for acceptor substrate specificity of the human β1,3-glucuronosyltransferases GlcAT-I and GlcAT-P involved in glycosaminoglycan and HNK-1 carbohydrate epitope biosynthesis, respectively. Glycobiology 2007; 17:857-67. [PMID: 17567734 DOI: 10.1093/glycob/cwm055] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The human beta1,3-glucuronosyltransferases galactose-beta1,3-glucuronosyltransferase I (GlcAT-I) and galactose-beta1,3-glucuronosyltransferase P (GlcAT-P) are key enzymes involved in proteoglycan and HNK-1 carbohydrate epitope synthesis, respectively. Analysis of their acceptor specificity revealed that GlcAT-I was selective toward Galbeta1,3Gal (referred to as Gal2-Gal1), whereas GlcAT-P presented a broader profile. To understand the molecular basis of acceptor substrate recognition, we constructed mutants and chimeric enzymes based on multiple sequence alignment and structural information. The drastic effect of mutations of Glu227, Arg247, Asp252, and Glu281 on GlcAT-I activity indicated a key role for the hydrogen bond network formed by these four conserved residues in dictating Gal2 binding. Investigation of GlcAT-I determinants governing Gal1 recognition showed that Trp243 could not be replaced by its counterpart Phe in GlcAT-P. This result combined with molecular modeling provided evidence for the importance of stacking interactions with Trp at position 243 in the selectivity of GlcAT-I toward Galbeta1,3Gal. Mutation of Gln318 predicted to be hydrogen-bonded to 6-hydroxyl of Gal1 had little effect on GlcAT-I activity, reinforcing the role of Trp243 in Gal1 binding. Substitution of Phe245 in GlcAT-P by Ala selectively abolished Galbeta1,3Gal activity, also highlighting the importance of an aromatic residue at this position in defining the specificity of GlcAT-P. Finally, substituting Phe245, Val320, or Asn321 in GlcAT-P predicted to interact with N-acetylglucosamine (GlcNAc), by their counterpart in GlcAT-I, moderately affected the activity toward the reference substrate of GlcAT-P, N-acetyllactosamine, indicating that its active site tolerates amino acid substitutions, an observation that parallels its promiscuous substrate profile. Taken together, the data clearly define key residues governing the specificity of beta1,3-glucuronosyltransferases.
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Miley MJ, Zielinska AK, Keenan JE, Bratton SM, Radominska-Pandya A, Redinbo MR. Crystal structure of the cofactor-binding domain of the human phase II drug-metabolism enzyme UDP-glucuronosyltransferase 2B7. J Mol Biol 2007; 369:498-511. [PMID: 17442341 PMCID: PMC1976284 DOI: 10.1016/j.jmb.2007.03.066] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 03/22/2007] [Accepted: 03/24/2007] [Indexed: 10/23/2022]
Abstract
Human UDP-glucuronosyltransferases (UGT) are the dominant phase II conjugative drug metabolism enzymes that also play a central role in processing a range of endobiotic compounds. UGTs catalyze the covalent addition of glucuronic acid sugar moieties to a host of therapeutics and environmental toxins, as well as to a variety of endogenous steroids and other signaling molecules. We report the 1.8-A resolution apo crystal structure of the UDP-glucuronic acid binding domain of human UGT isoform 2B7 (UGT2B7), which catalyzes the conjugative elimination of opioid, antiviral, and anticancer drugs. This is the first crystal structure of any region of a mammalian UGT drug metabolism enzyme. Designated UGT2B7 mutants at residues predicted to interact with the UDP-glucuronic acid cofactor exhibited significantly impaired catalytic activity, with maximum effects observed for amino acids closest to the glucuronic acid sugar transferred to the acceptor molecule. Homology modeling of UGT2B7 with related plant flavonoid glucosyltransferases indicates human UGTs share a common catalytic mechanism. Point mutations at predicted catalytic residues in UGT2B7 abrogated activity, strongly suggesting human UGTs also utilize a serine hydrolase-like catalytic mechanism to facilitate glucuronic acid transfer.
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Affiliation(s)
- Michael J. Miley
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3290 USA
| | - Agnieszka K. Zielinska
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | - Jeffrey E. Keenan
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3290 USA
| | - Stacie M. Bratton
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | - Anna Radominska-Pandya
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | - Matthew R. Redinbo
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3290 USA
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3290 USA
- Program in Molecular Biology and Biotechnology, and the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3290 USA
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Lévesque E, Girard H, Journault K, Lépine J, Guillemette C. Regulation of the UGT1A1 bilirubin-conjugating pathway: role of a new splicing event at the UGT1A locus. Hepatology 2007; 45:128-38. [PMID: 17187418 DOI: 10.1002/hep.21464] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
UNLABELLED UDP-glucuronosyltransferase 1A1 (UGT1A1) is involved in a wide range of biological and pharmacological processes because of its critical role in the conjugation of a diverse array of endogenous and exogenous compounds. We now describe a new UGT1A1 isoform, referred to as isoform 2 (UGT1A1_i2), encoded by a 1495-bp complementary DNA isolated from human liver and generated by an alternative splicing event involving an additional exon found at the 3' end of the UGT1A locus. The N-terminal portion of the 45-kd UGT1A1_i2 protein is identical to UGT1A1 (55 kd, UGT1A1_i1); however, UGT1A1_i2 contains a unique 10-residue sequence instead of the 99-amino acid C-terminal domain of UGT1A1_i1. RT-PCR and Western blot analyses with a specific antibody against UGT1A1 indicate that isoform 2 is differentially expressed in liver, kidney, colon, and small intestine at levels that reach or exceed, for some tissues, those of isoform 1. Western blots of different cell fractions and immunofluorescence experiments indicate that UGT1A1_i1 and UGT1A1_i2 colocalize in microsomes. Functional enzymatic data indicate that UGT1A1_i2, which lacks transferase activity when stably expressed alone in HEK293 cells, acts as a negative modulator of UGT1A1_i1, decreasing its activity by up to 78%. Coimmunoprecipitation of UGT1A1_i1 and UGT1A1_i2 suggests that this repression may occur via direct protein-protein interactions. CONCLUSION Our results indicate that this newly discovered alternative splicing mechanism at the UGT1A locus amplifies the structural diversity of human UGT proteins and describes the identification of an additional posttranscriptional regulatory mechanism of the glucuronidation pathway.
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Affiliation(s)
- Eric Lévesque
- Laboratory of Pharmacogenomics, Oncology and Molecular Endocrinology Research Center, CHUL Research Center and Faculty of Pharmacy, Laval University, Québec, Canada
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Hanioka N, Takeda Y, Jinno H, Tanaka-Kagawa T, Naito S, Koeda A, Shimizu T, Nomura M, Narimatsu S. Functional characterization of human and cynomolgus monkey UDP-glucuronosyltransferase 1A6 enzymes. Chem Biol Interact 2006; 164:136-45. [PMID: 17027947 DOI: 10.1016/j.cbi.2006.09.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2006] [Revised: 09/11/2006] [Accepted: 09/11/2006] [Indexed: 12/01/2022]
Abstract
UDP-glucuronosyltransferase 1A6 (UGT1A6) is a major isoform in the human liver that glucuronidates numerous drugs, environmental chemicals and endogenous substrates. In this study, human and cynomolgus monkey UGT1A6 cDNAs (humUGT1A6 and monUGT1A6, respectively) were cloned, and the corresponding proteins were heterologously expressed in yeast cells to identify the functions of primate UGT1A6s. The enzymatic properties of UGT1A6 proteins were characterized by the kinetic analysis of serotonin (5-hydroxytryptamine, 5-HT) and 4-methylumbelliferone (4-MU) glucuronidation. humUGT1A6 and monUGT1A6 showed 96% identity in their nucleotide and amino acid sequences. Immunoblotting analysis using an antibody raised against human UGT1A6 showed that protein staining intensities were different between human and cynomolgus monkey UGT1A6 enzymes in microsomal fractions from livers and yeast cells, although both enzymes were detectable. The apparent K(m) value (15 mM) for 5-HT glucuronidation of cynomolgus monkey liver microsomes was significantly higher than that (8.6mM) of human liver microsomes, whereas V(max) values were lower in cynomolgus monkeys (2.8 nmol/min/mg protein) than in humans (8.6 nmol/min/mg protein). No significant species difference was observed in K(m) (approximately 90 microM) or V(max) (approximately 25 nmol/min/mg protein) values for liver microsomal 4-MU glucuronidation. In yeast cell microsomes, K(m) values (approximately 6mM) for 5-HT glucuronidation by recombinant UGT1A6s were similar, while a V(max) value (0.1nmol/min/mg protein) of monUGT1A6 was significantly lower than that (0.7 nmol/min/mg protein) of humUGT1A6. In 4-MU glucuronidation, both K(m) (210 microM) and V(max) (3.5 nmol/min/mg protein) values of monUGT1A6 were significantly higher than those of humUGT1A6 (K(m), 110 microM; V(max), 1.5nmol/min/mg protein). These findings suggest that the enzymatic properties of UGT1A6 were extensively different between humans and cynomolgus monkeys, although humUGT1A6 and monUGT1A6 showed high homology at the amino acid level. The information gained in this study should help with in vivo extrapolation and to assess the toxicity of xenobiotics.
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Affiliation(s)
- Nobumitsu Hanioka
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan
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Barré L, Venkatesan N, Magdalou J, Netter P, Fournel-Gigleux S, Ouzzine M. Evidence of calcium‐dependent pathway in the regulation of human β1,3‐glucuronosyltransferase‐1 (GlcAT‐I) gene expression: a key enzyme in proteoglycan synthesis. FASEB J 2006; 20:1692-4. [PMID: 16807373 DOI: 10.1096/fj.05-5073fje] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The importance of heparan- and chondroitin-sulfate proteoglycans in physiological and pathological processes led to the investigation of the regulation of beta1,3-glucuronosyltransferase I (GlcAT-I), responsible for the completion of glycosaminoglycan-protein linkage tetrasaccharide, a key step prior to polymerization of chondroitin- and heparan-sulfate chains. We have cloned and functionally characterized GlcAT-I 5'-flanking regulatory region. Mutation analysis and electrophoretic mobility shift assays demonstrated the importance of Sp1 motif located at -65/-56 position in promoter activity. Furthermore, we found that elevation of intracellular calcium concentration by the calcium ionophore ionomycin stimulated GlcAT-I gene expression as well as glycosaminoglycan chain synthesis in HeLa cells. Bisanthracycline, an anti-Sp1 compound, inhibited GlcAT-I basal promoter activity and suppressed ionomycin induction, suggesting the importance of Sp1 in calcium induction of GlcAT-I gene expression. Nuclear protein extracts from ionomycin-induced cells exhibited an increased DNA binding of Sp1 factor to the consensus sequence at position -65/-56. Signaling pathway analysis and MEK inhibition studies revealed the important role of p42/p44 MAPK in the stimulation of GlcAT-I promoter activity by ionomycin. The present study identifies, for the first time, GlcAT-I as a target of calcium-dependent signaling pathway and evidences the critical role of Sp1 transcription factor in the activation of GlcAT-I expression.
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Affiliation(s)
- Lydia Barré
- UMR CNRS 7561-Université Henri Poincaré Nancy 1, Faculté de Médecine, BP 184, Vandoeuvre-lès-Nancy 54505, France
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Abstract
The uridine diphosphoglucuronosyltransferases (UGTs) belong to a superfamily of enzymes that catalyse the glucuronidation of numerous endobiotics and xenobiotics. Several human hepatic and extrahepatic UGT isozymes have been characterized with respect to their substrate specificity, tissue expression and gene structure. Genetic polymorphisms have been identified for almost all the UGT family members. A wide variety of anticancer drugs, dietary chemopreventives and carcinogens are known to be conjugated by members of both UGT1A and UGT2B subfamilies. This review examines in detail each UGT isozyme known to be associated with cancer and carcinogenesis. The cancer-related substrates for several UGTs are summarized, and the functionally relevant genetic polymorphisms of UGTs are reviewed. A number of genotype-phenotype association studies have been carried out to characterize the role of UGT pharmacogenetics in several types of cancer, and these examples are discussed here. In summary, this review focuses on the role of the human UGT genetic polymorphisms in carcinogenesis, chemoprevention and cancer risk.
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Affiliation(s)
- S Nagar
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA.
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