1
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Takeda K, Manago K, Morita A, Kawai YK, Yasuo N, Sekijima M, Ikenaka Y, Hashimoto T, Minato R, Oyamada Y, Horikoshi K, Suzuki H, Ishizuka M, Nakayama SMM. Toxicokinetic analysis of the anticoagulant rodenticides warfarin & diphacinone in Egyptian fruit bats (Rousettus aegyptiacus) as a comparative sensitivity assessment for Bonin fruit bats (Pteropus pselaphon). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 243:113971. [PMID: 35981482 DOI: 10.1016/j.ecoenv.2022.113971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 08/09/2022] [Accepted: 08/11/2022] [Indexed: 06/15/2023]
Abstract
Anticoagulant rodenticides have been widely used to eliminate wild rodents, which as invasive species on remote islands can disturb ecosystems. Since rodenticides can cause wildlife poisoning, it is necessary to evaluate the sensitivity of local mammals and birds to the poisons to ensure the rodenticides are used effectively. The Bonin Islands are an archipelago located 1000 km southeast of the Japanese mainland and are famous for the unique ecosystems. Here the first-generation anticoagulant rodenticide diphacinone has been used against introduced black rats (Rattus rattus). The only land mammal native to the archipelago is the Bonin fruit bat (Pteropus pselaphon), but little is known regarding its sensitivity to rodenticides. In this study, the Egyptian fruit bats (Rousettus aegyptiacus) was used as a model animal for in vivo pharmacokinetics and pharmacodynamics analysis and in vitro enzyme kinetics using their hepatic microsomal fractions. The structure of vitamin K epoxide reductase (VKORC1), the target protein of the rodenticide in the Bonin fruit bat, was predicted from its genome and its binding affinity to rodenticides was evaluated. The Egyptian fruit bats excreted diphacinone slowly and showed similar sensitivity to rats. In contrast, they excreted warfarin, another first-generation rodenticide, faster than rats and recovered from the toxic effect faster. An in silico binding study also indicated that the VKORC1 of fruit bats is relatively tolerant to warfarin, but binds strongly to diphacinone. These results suggest that even chemicals with the same mode of action display different sensitivities in different species: fruit bat species are relatively resistant to warfarin, but vulnerable to diphacinone.
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Affiliation(s)
- Kazuki Takeda
- Laboratory of Toxicology, School of Veterinary Medicine, Kitasato University, E23-35-1, Towada, Aomori 034-0021, Japan; Department of Computer Science, Tokyo Institute of Technology, 4259-J3-1818, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-0026, Japan; Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, N18 W9, Kita-ku, Sapporo 060-0818, Japan
| | - Kosuke Manago
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, N18 W9, Kita-ku, Sapporo 060-0818, Japan
| | - Ayuko Morita
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, N18 W9, Kita-ku, Sapporo 060-0818, Japan
| | - Yusuke K Kawai
- Department of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan
| | - Nobuaki Yasuo
- Department of Computer Science, Tokyo Institute of Technology, 4259-J3-1818, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-0026, Japan
| | - Masakazu Sekijima
- Department of Computer Science, Tokyo Institute of Technology, 4259-J3-1818, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-0026, Japan
| | - Yoshinori Ikenaka
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, N18 W9, Kita-ku, Sapporo 060-0818, Japan; Water Research Group, Unit for Environmental Sciences and Management, North-West University, 11 Hoffman Street, Potchefstroom 2531, South Africa; Translational Research Unit, Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan; One Health Research Center, Hokkaido University, Sapporo, Japan
| | - Takuma Hashimoto
- Japan Wildlife Research Center, Kotobashi 3-3-7, Sumida-ku, Tokyo 130-8606, Japan
| | - Ryuichi Minato
- Japan Wildlife Research Center, Kotobashi 3-3-7, Sumida-ku, Tokyo 130-8606, Japan
| | - Yusuke Oyamada
- Japan Wildlife Research Center, Kotobashi 3-3-7, Sumida-ku, Tokyo 130-8606, Japan
| | - Kazuo Horikoshi
- Institute of Boninology, Azanishimachi, Chichijima, Tokyo 100-2101, Japan
| | - Hajime Suzuki
- Institute of Boninology, Azanishimachi, Chichijima, Tokyo 100-2101, Japan
| | - Mayumi Ishizuka
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, N18 W9, Kita-ku, Sapporo 060-0818, Japan
| | - Shouta M M Nakayama
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, N18 W9, Kita-ku, Sapporo 060-0818, Japan; School of Veterinary Medicine, The University of Zambia, Great East Road PO Box 32379, Lusaka, Zambia.
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2
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Liu S, Shen G, Li W. Structural and cellular basis of vitamin K antagonism. J Thromb Haemost 2022; 20:1971-1983. [PMID: 35748323 DOI: 10.1111/jth.15800] [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: 05/02/2022] [Revised: 06/15/2022] [Accepted: 06/20/2022] [Indexed: 11/30/2022]
Abstract
Vitamin K antagonists (VKAs), such as warfarin, are oral anticoagulants widely used to treat and prevent thromboembolic diseases. Therapeutic use of these drugs requires frequent monitoring and dose adjustments, whereas overdose often causes severe bleeding. Addressing these drawbacks requires mechanistic understandings at cellular and structural levels. As the target of VKAs, vitamin K epoxide reductase (VKOR) generates the active, hydroquinone form of vitamin K, which in turn drives the γ-carboxylation of several coagulation factors required for their activity. Crystal structures revealed that VKAs inhibit VKOR via mimicking its catalytic process. At the active site, two strong hydrogen bonds that facilitate the catalysis also afford the binding specificity for VKAs. Binding of VKAs induces a global change from open to closed conformation. Similar conformational change is induced by substrate binding to promote an electron transfer process that reduces the VKOR active site. In the cellular environment, reducing partner proteins or small reducing molecules may afford electrons to maintain the VKOR activity. The catalysis and VKA inhibition require VKOR in different cellular redox states, explaining the complex kinetics behavior of VKAs. Recent studies also revealed the mechanisms underlying warfarin resistance, warfarin dose variation, and antidoting by vitamin K. These mechanistic understandings may lead to improved anticoagulation strategies targeting the vitamin K cycle.
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Affiliation(s)
- Shixuan Liu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Guomin Shen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
- Henan International Joint Laboratory of Thrombosis and Hemostasis, School of Basic Medical Science, Henan University of Science and Technology, Luoyang, China
- Department of Cell Biology, Harbin Medical University, Harbin, China
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
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3
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Sato R, Watanabe K, Kamata R, Takeda K. Development of a sandwich enzyme-linked immunosorbent assay (ELISA) to quantify γ-glutamyl-carboxylated clotting factor IX and assess redox susceptibility of anticoagulant chemicals. J Vet Med Sci 2022; 84:804-808. [PMID: 35444089 PMCID: PMC9246686 DOI: 10.1292/jvms.22-0079] [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] [Indexed: 11/22/2022] Open
Abstract
Anticoagulant chemicals (ACCs) such as warfarin are widely used in medical applications
as well as for their rodenticide properties. Their efficacy is greatly influenced by
polymorphisms in the gene encoding vitamin K epoxide reductase (VKOR). Evaluation of the
activity of ACCs toward VKOR variants is essential to determine their proper use.
Presently, this is achieved by co-expressing VKOR of Rattus Norvegicus
and human clotting factor IX in cultured cells and measuring inhibition of vitamin
K-dependent gamma-glutamyl carboxylation of factor IX (glaFIX) activity. However, glaFIX
has only been quantified using indirect methods like blood coagulation assays. We have
developed a sandwich enzyme-linked immunosorbent assay using a glaFIX-specific antibody to
quantify glaFIX and used this to analyze inhibition of VKOR activity by warfarin.
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Affiliation(s)
- Ryo Sato
- Laboratory of Toxicology, School of Veterinary Medicine, Kitasato University
| | - Kanami Watanabe
- Laboratory of Toxicology, School of Veterinary Medicine, Kitasato University
| | - Ryo Kamata
- Laboratory of Toxicology, School of Veterinary Medicine, Kitasato University
| | - Kazuki Takeda
- Laboratory of Toxicology, School of Veterinary Medicine, Kitasato University.,Department of Computer Science, Tokyo Institute of Technology
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Chetot T, Benoit E, Lambert V, Lattard V. Overexpression of protein disulfide isomerase enhances vitamin K epoxide reductase activity. Biochem Cell Biol 2022; 100:152-161. [PMID: 35007172 DOI: 10.1139/bcb-2021-0441] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vitamin K epoxide reductase (VKOR) activity is catalyzed by the VKORC1 enzyme. It is the target of vitamin K antagonists (VKA). Numerous mutations of VKORC1 have been reported and have been suspected to confer resistance to VKA and/or affect its velocity. Nevertheless, the results between studies have been conflicting, the functional characterization of these mutations in a cell system being complex due to the interweaving of VKOR activity in the vitamin K cycle. In this study, a new cellular approach was implemented to globally evaluate the vitamin K cycle in the HEK293 cells. This global approach was based on the vitamin K quinone/vitamin K epoxide (K/KO) balance. In the presence of VKA or when the VKORC1/VKORC1L1 were knocked out, the K/KO balance decreased significantly due to an accumulation of vitamin KO. On the contrary, when VKORC1 was overexpressed, the balance remained unchanged, demonstrating a limitation of the VKOR activity. This limitation was shown to be due to an insufficient expression of the activation partner of VKORC1, as overexpressing the protein disulfide isomerase (PDI) overcomes the limitation. This study is the first to demonstrate a functional interaction between VKORC1 and the PDI enzyme.
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Affiliation(s)
| | | | | | - Virginie Lattard
- VetAgro Sup, 88622, USC1233 INRAe-VetAgroSup, Marcy-l'Etoile, France, 69280;
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Incremental Value of Genotype Bins over the HAS-BLED Score for the Prediction of Bleeding Risk in Warfarin-Treated Patients with Atrial Fibrillation. Cardiol Res Pract 2021; 2021:9030005. [PMID: 34858664 PMCID: PMC8632379 DOI: 10.1155/2021/9030005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 09/25/2021] [Accepted: 10/26/2021] [Indexed: 11/17/2022] Open
Abstract
Background This study aimed to analyse the role of the HAS-BLED score with the addition of genotype bins for bleeding risk prediction in warfarin-treated patients with atrial fibrillation (AF). Methods and Results Consecutive patients with AF on initial warfarin treatment were recruited. For each patient, CYP2C9 ∗ 3 and VKORC1-1639 A/G genotyping was performed to create 3 genotype functional bins. The predictive values of the HAS-BLED score with or without the addition of genotype bins were compared. According to the carrier status of the genotype bins, the numbers of normal, sensitive, and highly sensitive responders among 526 patients were 64 (12.17%), 422 (80.23%), and 40 (7.60%), respectively. A highly sensitive response was independently associated with clinically relevant bleeding (HR: 3.85, 95% CI: 1.88-7.91, P=0.001) and major bleeding (HR:3.75, 95% CI: 1.17-11.97, P=0.03). With the addition of genotype bins, the performance of the HAS-BLED score for bleeding risk prediction was significantly improved (c-statistic from 0.60 to 0.64 for clinically relevant bleeding and from 0.64 to 0.70 for major bleeding, P < 0.01). Using the integrated discriminatory, net reclassification improvement, and decision curve analysis, the HAS-BLED score plus genotype bins could perform better in predicting any clinically relevant bleeding than the HAS-BLED score alone. Conclusions Genotypes have an incremental predictive value when combined with the HAS-BLED score for the prediction of clinically relevant bleeding in warfarin-treated patients with AF.
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6
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Competitive tight-binding inhibition of VKORC1 underlies warfarin dosage variation and antidotal efficacy. Blood Adv 2021; 4:2202-2212. [PMID: 32433747 DOI: 10.1182/bloodadvances.2020001750] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 04/24/2020] [Indexed: 11/20/2022] Open
Abstract
Dose control of warfarin is a major complication in anticoagulation therapy and overdose is reversed by the vitamin K antidote. Improving the dosage management and antidotal efficacy requires mechanistic understanding. Here we find that effects of the major predictor of warfarin dosage, SNP -1639 G>A, follow a general correlation that warfarin 50% inhibitory concentration decreases with cellular level of vitamin K epoxide reductase (VKORC1), suggesting stoichiometric inhibition. Characterization of the inhibition kinetics required the use of microsomal VKORC1 with a native reductant, glutathione, that enables effective warfarin inhibition in vitro. The kinetics data can be fitted with the Morrison equation, giving a nanomolar inhibition constant and demonstrating that warfarin is a tight-binding inhibitor. However, warfarin is released from purified VKORC1-warfarin complex with increasing amount of vitamin K, indicating competitive inhibition. The competition occurs also in cells, resulting in rescued VKORC1 activity that augments the antidotal effects of vitamin K. Taken together, warfarin is a competitive inhibitor that binds VKORC1 tightly and inhibits at a stoichiometric (1:1) concentration, whereas exceeding the VKORC1 level results in warfarin overdose. Thus, warfarin dosage control should use VKORC1 level as a major indicator, and improved antidotes may be designed based on their competition with warfarin.
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Takeda K, Ikenaka Y, Fourches D, Tanaka KD, Nakayama SMM, Triki D, Li X, Igarashi M, Tanikawa T, Ishizuka M. The VKORC1 ER-luminal loop mutation (Leu76Pro) leads to a significant resistance to warfarin in black rats (Rattus rattus). PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2021; 173:104774. [PMID: 33771253 DOI: 10.1016/j.pestbp.2021.104774] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 12/10/2020] [Accepted: 01/04/2021] [Indexed: 06/12/2023]
Abstract
Well-known 4-hydroxycoumarin derivatives, such as warfarin, act as inhibitors of the vitamin K epoxide reductase (VKOR) and are used as anticoagulants. Mutations of the VKOR enzyme can lead to resistance to those compounds. This has been a problem in using them as medicine or rodenticide. Most of these mutations lie in the vicinity of potential warfarin-binding sites within the ER-luminal loop structure (Lys30, Phe55) and the transmembrane helix (Tyr138). However, a VKOR mutation found in Tokyo in warfarin-resistant rats does not follow that pattern (Leu76Pro), and its effect on VKOR function and structure remains unclear. We conducted both in vitro kinetic analyses and in silico docking studies to characterize the VKOR mutant. On the one hand, resistant rats (R-rats) showed a 37.5-fold increased IC50 value to warfarin when compared to susceptible rats (S-rats); on the other hand, R-rats showed a 16.5-fold lower basal VKOR activity (Vmax/Km). Docking calculations exhibited that the mutated VKOR of R-rats has a decreased affinity for warfarin. Molecular dynamics simulations further revealed that VKOR-associated warfarin was more exposed to solvents in R-rats and key interactions between Lys30, Phe55, and warfarin were less favored. This study concludes that a single mutation of VKOR at position 76 leads to a significant resistance to warfarin by modifying the types and numbers of intermolecular interactions between the two.
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Affiliation(s)
- Kazuki Takeda
- Laboratory of Toxicology, Department of Environmental Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo 060-0818, Japan
| | - Yoshinori Ikenaka
- Laboratory of Toxicology, Department of Environmental Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo 060-0818, Japan; Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Denis Fourches
- Department of Chemistry, Bioinformatics Research Center, North Carolina State University, Raleigh, NC, USA
| | - Kazuyuki D Tanaka
- Technical Research Laboratory, IKARI SHODOKU CO., Ltd., Narashino, Chiba, Japan
| | - Shouta M M Nakayama
- Laboratory of Toxicology, Department of Environmental Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo 060-0818, Japan
| | - Dhoha Triki
- Department of Chemistry, Bioinformatics Research Center, North Carolina State University, Raleigh, NC, USA
| | - Xinhao Li
- Department of Chemistry, Bioinformatics Research Center, North Carolina State University, Raleigh, NC, USA
| | - Manabu Igarashi
- Division of Global Epidemiology, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan; Global Station for Zoonosis Control, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan
| | - Tsutomu Tanikawa
- Technical Research Laboratory, IKARI SHODOKU CO., Ltd., Narashino, Chiba, Japan
| | - Mayumi Ishizuka
- Laboratory of Toxicology, Department of Environmental Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo 060-0818, Japan.
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8
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Li S, Liu S, Yang Y, Li W. Characterization of Warfarin Inhibition Kinetics Requires Stabilization of Intramembrane Vitamin K Epoxide Reductases. J Mol Biol 2020; 432:5197-5208. [PMID: 32445640 DOI: 10.1016/j.jmb.2020.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 04/24/2020] [Accepted: 05/14/2020] [Indexed: 01/04/2023]
Abstract
Intramembrane enzymes are often difficult for biochemical characterization. Human vitamin K epoxide reductase (VKOR) is the target of warfarin. However, this intramembrane enzyme becomes insensitive to warfarin inhibition in vitro, preventing the characterization of inhibition kinetics for decades. Here we employ structural biology methods to identify stable VKOR and VKOR-like proteins and purify them to near homogeneity. We find that the key to maintain their warfarin sensitivity is to stabilize their native protein conformation in vitro. Reduced glutathione drastically increases the warfarin sensitivity of a VKOR-like protein from Takifugu rubripes, presumably through maintaining a disulfide-bonded conformation. Effective inhibition of human VKOR-like requires also the use of LMNG, a mild detergent developed for crystallography to increase membrane protein stability. Human VKOR needs to be preserved in ER-enriched microsomes to exhibit warfarin sensitivity, whereas human VKOR purified in LMNG is stable only with pre-bound warfarin. Under these optimal conditions, warfarin inhibits with tight-binding kinetics. Overall, our studies show that structural biology methods are ideal for stabilizing intramembrane enzymes. Optimizing toward their inhibitor-binding conformation enables the characterization of enzyme kinetics in difficult cases.
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Affiliation(s)
- Shuang Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Shixuan Liu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yihu Yang
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
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9
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Takeda K, Morita A, Ikenaka Y, Nakayama SMM, Ishizuka M. Comparison of two reducing agents dithiothreitol and tris(3-hydroxypropyl)phosphine for in vitro kinetic assay of vitamin K epoxide reductase. Vet Anim Sci 2020; 9:100095. [PMID: 32734105 PMCID: PMC7386777 DOI: 10.1016/j.vas.2020.100095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 01/15/2020] [Accepted: 01/30/2020] [Indexed: 11/30/2022] Open
Abstract
Vitamin K epoxide reductase (VKOR) is a target enzyme for anticoagulants, such as warfarin, that are used as medicines or rodenticides. Assessing VKOR activity is required to ensure the proper usage of these drugs. Dithiothreitol (DTT) is a typical disulfide reductant that is used as a substrate for in vitro VKOR assays. However, DTT is considered problematic because of its side effects. Tris(3-hydroxypropyl)phosphine (THP) has been found to be a reliable alternative to DTT, as shown by kinetic analyses of the VKOR with them. THP showed significantly lower Vmax and Km values than those of DTT; however, there was no significant difference in their Vmax/Km and IC50 for warfarin.
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Affiliation(s)
- Kazuki Takeda
- Department of Environmental Sciences, Laboratory of Toxicology, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo 060-0818, Japan
| | - Ayuko Morita
- Department of Environmental Sciences, Laboratory of Toxicology, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo 060-0818, Japan
| | - Yoshinori Ikenaka
- Department of Environmental Sciences, Laboratory of Toxicology, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo 060-0818, Japan.,Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa
| | - Shouta M M Nakayama
- Department of Environmental Sciences, Laboratory of Toxicology, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo 060-0818, Japan
| | - Mayumi Ishizuka
- Department of Environmental Sciences, Laboratory of Toxicology, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo 060-0818, Japan
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10
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Chen X, Wei Q, Lu Q, Zhao Z, Yu Z, Zhang Y. Sodium dehydroacetate induces coagulation dysfunction by inhibiting liver vitamin K epoxide reductase complex subunit 1 in Wistar rats. Res Vet Sci 2019; 124:399-405. [PMID: 31078787 DOI: 10.1016/j.rvsc.2019.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 04/30/2019] [Accepted: 05/03/2019] [Indexed: 02/06/2023]
Abstract
Sodium dehydroacetate (Na-DHA), an antibiotic agent that combats growth of bacteria, fungi, and yeast, is used as a preservative in animal feed, food, and cosmetics. We previously reported that Na-DHA induces coagulation anomalies in Wistar rats, but the anticoagulant mechanism of Na-DHA remains to be established. Here we report that Na-DHA prolonged prothrombin time (PT) and activated partial thromboplastin time (APTT) in male and female Wistar rats. In addition, Na-DHA decreased vitamin K (VK) levels and increased the levels of protein induced by vitamin K absence/antagonist-II (PIVKA-II) in rat serum. Moreover, we found that treatment with VK not only reversed Na-DHA-decreased serum VK and -increased PIVKA-II levels, but also attenuated Na-DHA-prolonged PT and APTT, suggesting that Na-DHA-decreased serum VK level contributes to the anticoagulation due to Na-DHA. Further we found that Na-DHA inhibited vitamin K epoxide reductase complex subunit 1 (VKORC1), a key enzyme in VK recycling, in the liver tissue of Wistar rats, as evidenced by reduced mRNA and protein levels of VKORC1 following Na-DHA treatment. Taken together, our data indicate that Na-DHA inhibits liver VKORC1, resulting in a decrease of serum VK levels, leading to abnormal coagulation in rats.
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Affiliation(s)
- Xin Chen
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, PR China
| | - Qianhan Wei
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, PR China
| | - Qianqian Lu
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, PR China
| | - Zeting Zhao
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, PR China
| | - Zhengrong Yu
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, PR China
| | - Yumei Zhang
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, PR China.
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11
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VKORC1 and VKORC1L1 have distinctly different oral anticoagulant dose-response characteristics and binding sites. Blood Adv 2019; 2:691-702. [PMID: 29581108 DOI: 10.1182/bloodadvances.2017006775] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 01/22/2018] [Indexed: 01/11/2023] Open
Abstract
Vitamin K reduction is catalyzed by 2 enzymes in vitro: the vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) and its isozyme VKORC1-like1 (VKORC1L1). In vivo, VKORC1 reduces vitamin K to sustain γ-carboxylation of vitamin K-dependent proteins, including coagulation factors. Inhibition of VKORC1 by oral anticoagulants (OACs) is clinically used in therapy and in prevention of thrombosis. However, OACs also inhibit VKORC1L1, which was previously shown to play a role in intracellular redox homeostasis in vitro. Here, we report data for the first time on specific inhibition of both VKOR enzymes for various OACs and rodenticides examined in a cell-based assay. Effects on endogenous VKORC1 and VKORC1L1 were independently investigated in genetically engineered HEK 293T cells that were knocked out for the respective genes by CRISPR/Cas9 technology. In general, dose-responses for 4-hydroxycoumarins and 1,3-indandiones were enzyme-dependent, with lower susceptibility for VKORC1L1 compared with VKORC1. In contrast, rodenticides exhibited nearly identical dose-responses for both enzymes. To explain the distinct inhibition pattern, we performed in silico modeling suggesting different warfarin binding sites for VKORC1 and VKORC1L1. We identified arginine residues at positions 38, 42, and 68 in the endoplasmatic reticulum luminal loop of VKORC1L1 responsible for charge-stabilized warfarin binding, resulting in a binding pocket that is diametrically opposite to that of VKORC1. In conclusion, our findings provide insight into structural and molecular drug binding on VKORC1, and especially on VKORC1L1.
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Abstract
Vitamin K (VK) is an essential cofactor for the post-translational conversion of peptide-bound glutamate to γ-carboxyglutamate. The resultant vitamin K-dependent proteins are known or postulated to possess a variety of biological functions, chiefly in the maintenance of hemostasis. The vitamin K cycle is a cellular pathway that drives γ-carboxylation and recycling of VK via γ-carboxyglutamyl carboxylase (GGCX) and vitamin K epoxide reductase (VKOR), respectively. In this review, we show how novel molecular biological approaches are providing new insights into the pathophysiological mechanisms caused by rare mutations of both GGCX and VKOR. We also discuss how other protein regulators influence the intermediary metabolism of VK, first through intestinal absorption and second through a pathway that converts some dietary phylloquinone to menadione, which is prenylated to menaquinone-4 (MK-4) in target tissues by UBIAD1. The contribution of MK-4 synthesis to VK functions is yet to be revealed.
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Affiliation(s)
- Martin J Shearer
- Centre for Haemostasis and Thrombosis, Guy's and St Thomas' NHS Foundation Trust, London SE1 7EH, United Kingdom;
| | - Toshio Okano
- Department of Hygienic Sciences, Kobe Pharmaceutical University, Kobe 658-8558 Japan;
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13
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Shen G, Li S, Cui W, Liu S, Liu Q, Yang Y, Gross M, Li W. Stabilization of warfarin-binding pocket of VKORC1 and VKORL1 by a peripheral region determines their different sensitivity to warfarin inhibition. J Thromb Haemost 2018; 16:1164-1175. [PMID: 29665197 PMCID: PMC6231229 DOI: 10.1111/jth.14127] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Indexed: 11/30/2022]
Abstract
Essentials VKORL1 and VKORC1 have a similar overall structure and warfarin-binding pocket. A peripheral region stabilizing this pocket controls warfarin sensitivity of the VKOR paralogs. A human single nucleotide polymorphism in this region renders VKORL1 sensitive to warfarin. A group of warfarin-resistant mutations in VKORC1 acts by disrupting peripheral interactions. SUMMARY Background The human genome encodes two paralogs of vitamin-K-epoxide reductase, VKORC1 and VKORL1, that support blood coagulation and other vitamin-K-dependent processes. Warfarin inhibits both enzymes, but VKORL1 is relatively resistant to warfarin. Objectives To understand the difference between VKORL1 and VKORC1, and the cause of warfarin-resistant (WR) mutations in VKORC1. Methods We performed systematic mutagenesis and analyzed warfarin responses with a cell-based activity assay. Mass spectrometry analyses were used to detect cellular redox state. Results VKORC1 and VKORL1 adopt a similar intracellular redox state with four-transmembrane-helix topology. Most WR mutations identified in VKORC1 also confer resistance in VKORL1, indicating that warfarin inhibits these paralogs at a common binding site. A group of WR mutations, distant from the warfarin-binding site, show significantly less resistance in VKORL1 than in VKORC1, implying that their different warfarin responses are determined by peripheral interactions. Remarkably, we identify a critical peripheral region in which single mutations, Glu37Lys or His46Tyr, drastically increase the warfarin sensitivity of VKORL1. In the background of these warfarin-sensitive VKORL1 mutants, WR mutations showing relative less resistance in wild-type VKORL1 become much more resistant, suggesting a structural conversion to resemble VKORC1. At this peripheral region, we also identified a human single nucleotide polymorphism that confers warfarin sensitivity of VKORL1. Conclusions Peripheral regions of VKORC1 and VKORL1 primarily maintain the stability of their common warfarin-binding pocket, and differences of such interactions determine their relative sensitivity to warfarin inhibition. This new model also explains most WR mutations located at the peripheral regions of VKORC1.
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Affiliation(s)
- G Shen
- Institute of Hemostasis and Thrombosis, College of Medicine, Henan University of Science and Technology, Luoyang, Henan, China
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
| | - S Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
| | - W Cui
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA
| | - S Liu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
| | - Q Liu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Y Yang
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
| | - M Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA
| | - W Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
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14
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Warfarin alters vitamin K metabolism: a surprising mechanism of VKORC1 uncoupling necessitates an additional reductase. Blood 2018; 131:2826-2835. [PMID: 29592891 DOI: 10.1182/blood-2017-09-804666] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 03/07/2018] [Indexed: 11/20/2022] Open
Abstract
The anticoagulant warfarin inhibits the vitamin K oxidoreductase (VKORC1), which generates vitamin K hydroquinone (KH2) required for the carboxylation and consequent activation of vitamin K-dependent (VKD) proteins. VKORC1 produces KH2 in 2 reactions: reduction of vitamin K epoxide (KO) to quinone (K), and then KH2 Our dissection of full reduction vs the individual reactions revealed a surprising mechanism of warfarin inhibition. Warfarin inhibition of KO to K reduction and carboxylation that requires full reduction were compared in wild-type VKORC1 or mutants (Y139H, Y139F) that cause warfarin resistance. Carboxylation was much more strongly inhibited (∼400-fold) than KO reduction (two- to threefold). The K to KH2 reaction was analyzed using low K concentrations that result from inhibition of KO to K. Carboxylation that required only K to KH2 reduction was inhibited much less than observed with the KO substrate that requires full VKORC1 reduction (eg, 2.5-fold vs 70-fold, respectively, in cells expressing wild-type VKORC1 and factor IX). The results indicate that warfarin uncouples the 2 reactions that fully reduce KO. Uncoupling was revealed because a second activity, a warfarin-resistant quinone reductase, was not present. In contrast, 293 cells expressing factor IX and this reductase activity showed much less inhibition of carboxylation. This activity therefore appears to cooperate with VKORC1 to accomplish full KO reduction. Cooperation during warfarin therapy would have significant consequences, as VKD proteins function in numerous physiologies in many tissues, but may be poorly carboxylated and dysfunctional if the second activity is not ubiquitously expressed similar to VKORC1.
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15
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Pezeshkpoor B, Czogalla KJ, Caspers M, Berkemeier AC, Liphardt K, Ghosh S, Kellner M, Ulrich S, Pavlova A, Oldenburg J. Variants in FIX propeptide associated with vitamin K antagonist hypersensitivity: functional analysis and additional data confirming the common founder mutations. Ann Hematol 2018; 97:1061-1069. [PMID: 29450643 DOI: 10.1007/s00277-018-3264-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/28/2018] [Indexed: 11/30/2022]
Abstract
One of the most common and unwanted side effects during oral anticoagulant therapy (OAT) is bleeding complications. In rare cases, vitamin K antagonist (VKA)-related bleeding events are associated with mutations affecting the F9 propeptide at amino acid position 37 due to a substitution of alanine to either valine or threonine. Based on our actual cohort of 18 patients, we update the knowledge on this rare phenotype and its origin. A founder mutation for both variants was reconfirmed by haplotype analysis of intronic and extragenic short tandem repeat (STR) polymorphisms with a higher prevalence in Switzerland than in other regions of Europe. Screening of healthy individuals for the presence of these F9 gene mutations did not identify any of these variants, thus proving the rare occurrence of this genotype. Furthermore, both variants were expressed in vitro and warfarin dose responses were studied. Our warfarin dose response analysis confirmed higher sensitivity of both variants to warfarin with the effect being more apparent for Ala37Thr. Thus, although F9 propeptide mutation-associated hypersensitivity to VKA is a rare phenomenon, awareness towards this bleeding phenotype is important to identify patients at risk.
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Affiliation(s)
- Behnaz Pezeshkpoor
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund-Freud-Str. 25, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany
| | - Katrin J Czogalla
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund-Freud-Str. 25, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany
| | - Michael Caspers
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund-Freud-Str. 25, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany
| | - Ann-Cristin Berkemeier
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund-Freud-Str. 25, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany
| | - Kerstin Liphardt
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund-Freud-Str. 25, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany
| | - Suvoshree Ghosh
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund-Freud-Str. 25, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany
| | | | - Silvia Ulrich
- Clinic of Pulmonology, University Hospital of Zürich, Zürich, Switzerland
| | - Anna Pavlova
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund-Freud-Str. 25, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany
| | - Johannes Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund-Freud-Str. 25, Bonn, Germany. .,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany.
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16
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Czogalla KJ, Biswas A, Höning K, Hornung V, Liphardt K, Watzka M, Oldenburg J. Warfarin and vitamin K compete for binding to Phe55 in human VKOR. Nat Struct Mol Biol 2016; 24:77-85. [PMID: 27941861 DOI: 10.1038/nsmb.3338] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 11/08/2016] [Indexed: 11/09/2022]
Abstract
Vitamin K epoxide reductase (VKOR) catalyzes the reduction of vitamin K quinone and vitamin K 2,3-epoxide, a process essential to sustain γ-carboxylation of vitamin K-dependent proteins. VKOR is also a therapeutic target of warfarin, a treatment for thrombotic disorders. However, the structural and functional basis of vitamin K reduction and the antagonism of warfarin inhibition remain elusive. Here, we identified putative binding sites of both K vitamers and warfarin on human VKOR. The predicted warfarin-binding site was verified by shifted dose-response curves of specified mutated residues. We used CRISPR-Cas9-engineered HEK 293T cells to assess the vitamin K quinone and vitamin K 2,3-epoxide reductase activities of VKOR variants to characterize the vitamin K naphthoquinone head- and isoprenoid side chain-binding regions. Our results challenge the prevailing concept of noncompetitive warfarin inhibition because K vitamers and warfarin share binding sites on VKOR that include Phe55, a key residue binding either the substrate or inhibitor.
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Affiliation(s)
- Katrin J Czogalla
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Arijit Biswas
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Klara Höning
- Institute of Molecular Medicine, University Hospital Bonn, Bonn, Germany
| | - Veit Hornung
- Institute of Molecular Medicine, University Hospital Bonn, Bonn, Germany.,Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Kerstin Liphardt
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Matthias Watzka
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany
| | - Johannes Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany.,Center for Rare Diseases Bonn (ZSEB), University Clinic Bonn, Bonn, Germany
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17
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Shen G, Cui W, Zhang H, Zhou F, Huang W, Liu Q, Yang Y, Li S, Bowman GR, Sadler JE, Gross ML, Li W. Warfarin traps human vitamin K epoxide reductase in an intermediate state during electron transfer. Nat Struct Mol Biol 2016; 24:69-76. [PMID: 27918545 DOI: 10.1038/nsmb.3333] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 10/24/2016] [Indexed: 01/25/2023]
Abstract
Although warfarin is the most widely used anticoagulant worldwide, the mechanism by which warfarin inhibits its target, human vitamin K epoxide reductase (hVKOR), remains unclear. Here we show that warfarin blocks a dynamic electron-transfer process in hVKOR. A major fraction of cellular hVKOR is in an intermediate redox state containing a Cys51-Cys132 disulfide, a characteristic accommodated by a four-transmembrane-helix structure of hVKOR. Warfarin selectively inhibits this major cellular form of hVKOR, whereas disruption of the Cys51-Cys132 disulfide impairs warfarin binding and causes warfarin resistance. Relying on binding interactions identified by cysteine alkylation footprinting and mass spectrometry coupled with mutagenesis analysis, we conducted structure simulations, which revealed a closed warfarin-binding pocket stabilized by the Cys51-Cys132 linkage. Understanding the selective warfarin inhibition of a specific redox state of hVKOR should enable the rational design of drugs that exploit the redox chemistry and associated conformational changes in hVKOR.
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Affiliation(s)
- Guomin Shen
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Weidong Cui
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Hao Zhang
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Fengbo Zhou
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Wei Huang
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA.,School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Qian Liu
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Forensic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yihu Yang
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Shuang Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Gregory R Bowman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - J Evan Sadler
- Division of Hematology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
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18
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Abstract
Vitamin K-dependent carboxylation, an essential posttranslational modification catalyzed by gamma-glutamyl carboxylase, is required for the biological functions of proteins that control blood coagulation, vascular calcification, bone metabolism, and other important physiological processes. Concomitant with carboxylation, reduced vitamin K (KH2) is oxidized to vitamin K epoxide (KO). KO must be recycled back to KH2 by the enzymes vitamin K epoxide reductase and vitamin K reductase in a pathway known as the vitamin K cycle. Our current knowledge about the enzymes of the vitamin K cycle is mainly based on in vitro studies of each individual enzymes under artificial conditions, which are of limited usefulness in understanding how the complex carboxylation process is carried out in the physiological environment. In this chapter, we review the current in vitro activity assays for vitamin K cycle enzymes. We describe the rationale, establishment, and application of cell-based assays for the functional study of these enzymes in the native cellular milieu. In these cell-based assays, different vitamin K-dependent proteins were designed and stably expressed in mammalian cells as reporter proteins to accommodate the readily used enzyme-linked immunosorbent assay for carboxylation efficiency evaluation. Additionally, recently emerged genome-editing techniques TALENs and CRISPR-Cas9 were used to knock out the endogenous enzymes in the reporter cell lines to eliminate the background. These cell-based assays are easy to scale up for high-throughput screening of inhibitors of vitamin K cycle enzymes and have been successfully used to clarify the genotypes and their clinical phenotypes of enzymes of the vitamin K cycle.
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Affiliation(s)
- J-K Tie
- University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.
| | - D W Stafford
- University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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19
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Goulois J, Chapuzet A, Lambert V, Chatron N, Tchertanov L, Legros L, Benoît E, Lattard V. Evidence of a target resistance to antivitamin K rodenticides in the roof rat Rattus rattus: identification and characterisation of a novel Y25F mutation in the Vkorc1 gene. PEST MANAGEMENT SCIENCE 2016; 72:544-550. [PMID: 25847836 DOI: 10.1002/ps.4020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/23/2015] [Accepted: 04/01/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND In spite of intensive use of bromadiolone, rodent control was inefficient on a farm infested by rats in Zaragoza, Spain. While metabolic resistance was previously described in this rodent species, the observation of a target resistance to antivitamin K rodenticides had been poorly documented in Rattus rattus. RESULTS From rats trapped on the farm, cytochrome b and Vkorc1 genes were amplified by PCR and sequenced in order to identify species and detect potential Vkorc1 mutations. VKORC1-deduced amino acid sequences were thus expressed in Pichia pastoris, and inhibition constants towards various rodenticides were determined. The ten rats trapped on the farm were all identified as R. rattus. They were found to be homozygous for the g.74A>T nucleotide replacement in exon 1 of the Vkorc1 gene, leading to p.Y25F mutation. This mutation led to increased apparent inhibition constants towards various rodenticides, probably caused by a partial loss of helical structure of TM4. CONCLUSION The p.Y25F mutation detected in the Vkorc1 gene in R. rattus trapped on the Spanish farm is associated with the resistance phenotype to bromadiolone that has been observed. It is the first evidence of target resistance to antivitamin K anticoagulants in R. rattus.
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Affiliation(s)
- Joffrey Goulois
- USC 1233 INRA-Vetagro Sup, Veterinary School of Lyon, Marcy l'Etoile, France
- Liphatech, Bonnel, France
| | - Audrey Chapuzet
- USC 1233 INRA-Vetagro Sup, Veterinary School of Lyon, Marcy l'Etoile, France
| | - Véronique Lambert
- USC 1233 INRA-Vetagro Sup, Veterinary School of Lyon, Marcy l'Etoile, France
| | - Nolan Chatron
- USC 1233 INRA-Vetagro Sup, Veterinary School of Lyon, Marcy l'Etoile, France
- Liphatech, Bonnel, France
- Centre de Mathématiques et de Leurs Applications (CMLA UMR 8536), Ecole Normale Supérieure de Cachan, Cachan, France
| | - Luba Tchertanov
- Centre de Mathématiques et de Leurs Applications (CMLA UMR 8536), Ecole Normale Supérieure de Cachan, Cachan, France
| | | | - Etienne Benoît
- USC 1233 INRA-Vetagro Sup, Veterinary School of Lyon, Marcy l'Etoile, France
| | - Virginie Lattard
- USC 1233 INRA-Vetagro Sup, Veterinary School of Lyon, Marcy l'Etoile, France
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20
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Structural Modeling Insights into Human VKORC1 Phenotypes. Nutrients 2015; 7:6837-51. [PMID: 26287237 PMCID: PMC4555152 DOI: 10.3390/nu7085313] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/03/2015] [Accepted: 08/06/2015] [Indexed: 11/17/2022] Open
Abstract
Vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) catalyses the reduction of vitamin K and its 2,3-epoxide essential to sustain γ-carboxylation of vitamin K-dependent proteins. Two different phenotypes are associated with mutations in human VKORC1. The majority of mutations cause resistance to 4-hydroxycoumarin- and indandione-based vitamin K antagonists (VKA) used in the prevention and therapy of thromboembolism. Patients with these mutations require greater doses of VKA for stable anticoagulation than patients without mutations. The second phenotype, a very rare autosomal-recessive bleeding disorder caused by combined deficiency of vitamin K dependent clotting factors type 2 (VKCFD2) arises from a homozygous Arg98Trp mutation. The bleeding phenotype can be corrected by vitamin K administration. Here, we summarize published experimental data and in silico modeling results in order to rationalize the mechanisms of VKA resistance and VKCFD2.
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21
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Oldenburg J, Watzka M, Bevans CG. VKORC1 and VKORC1L1: Why do Vertebrates Have Two Vitamin K 2,3-Epoxide Reductases? Nutrients 2015; 7:6250-80. [PMID: 26264021 PMCID: PMC4555119 DOI: 10.3390/nu7085280] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/08/2015] [Accepted: 07/15/2015] [Indexed: 01/01/2023] Open
Abstract
Among all cellular life on earth, with the exception of yeasts, fungi, and some prokaryotes, VKOR family homologs are ubiquitously encoded in nuclear genomes, suggesting ancient and important biological roles for these enzymes. Despite single gene and whole genome duplications on the largest evolutionary timescales, and the fact that most gene duplications eventually result in loss of one copy, it is surprising that all jawed vertebrates (gnathostomes) have retained two paralogous VKOR genes. Both VKOR paralogs function as entry points for nutritionally acquired and recycled K vitamers in the vitamin K cycle. Here we present phylogenetic evidence that the human paralogs likely arose earlier than gnathostomes, possibly in the ancestor of crown chordates. We ask why gnathostomes have maintained these paralogs throughout evolution and present a current summary of what we know. In particular, we look to published studies about tissue- and developmental stage-specific expression, enzymatic function, phylogeny, biological roles and associated pathways that together suggest subfunctionalization as a major influence in evolutionary fixation of both paralogs. Additionally, we investigate on what evolutionary timescale the paralogs arose and under what circumstances in order to gain insight into the biological raison d’être for both VKOR paralogs in gnathostomes.
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Affiliation(s)
- Johannes Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn 53105, Germany.
| | - Matthias Watzka
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn 53105, Germany.
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22
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Krettler C, Bevans CG, Reinhart C, Watzka M, Oldenburg J. Tris(3-hydroxypropyl)phosphine is superior to dithiothreitol for in vitro assessment of vitamin K 2,3-epoxide reductase activity. Anal Biochem 2015; 474:89-94. [DOI: 10.1016/j.ab.2014.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Accepted: 12/08/2014] [Indexed: 11/27/2022]
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23
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Shearer MJ, Newman P. Recent trends in the metabolism and cell biology of vitamin K with special reference to vitamin K cycling and MK-4 biosynthesis. J Lipid Res 2014; 55:345-62. [PMID: 24489112 PMCID: PMC3934721 DOI: 10.1194/jlr.r045559] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 01/30/2014] [Indexed: 12/25/2022] Open
Abstract
In contrast to other fat-soluble vitamins, dietary vitamin K is rapidly lost to the body resulting in comparatively low tissue stores. Deficiency is kept at bay by the ubiquity of vitamin K in the diet, synthesis by gut microflora in some species, and relatively low vitamin K cofactor requirements for γ-glutamyl carboxylation. However, as shown by fatal neonatal bleeding in mice that lack vitamin K epoxide reductase (VKOR), the low requirements are dependent on the ability of animals to regenerate vitamin K from its epoxide metabolite via the vitamin K cycle. The identification of the genes encoding VKOR and its paralog VKOR-like 1 (VKORL1) has accelerated understanding of the enzymology of this salvage pathway. In parallel, a novel human enzyme that participates in the cellular conversion of phylloquinone to menaquinone (MK)-4 was identified as UbiA prenyltransferase-containing domain 1 (UBIAD1). Recent studies suggest that side-chain cleavage of oral phylloquinone occurs in the intestine, and that menadione is a circulating precursor of tissue MK-4. The mechanisms and functions of vitamin K recycling and MK-4 synthesis have dominated advances made in vitamin K biochemistry over the last five years and, after a brief overview of general metabolism, are the main focuses of this review.
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Affiliation(s)
- Martin J. Shearer
- Centre for Haemostasis and Thrombosis, Guy's and St. Thomas’ NHS Foundation Trust, London SE1 7EH, UK; and
| | - Paul Newman
- Cancer Research UK London Research Institute, London WC2A 3LY, UK
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24
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Tie JK, Jin DY, Stafford DW. Conserved loop cysteines of vitamin K epoxide reductase complex subunit 1-like 1 (VKORC1L1) are involved in its active site regeneration. J Biol Chem 2014; 289:9396-407. [PMID: 24532791 DOI: 10.1074/jbc.m113.534446] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vitamin K epoxide reductase complex subunit 1 (VKORC1) reduces vitamin K epoxide in the vitamin K cycle for post-translational modification of proteins that are involved in a variety of biological functions. However, the physiological function of VKORC1-like 1 (VKORC1L1), a paralogous enzyme sharing about 50% protein identity with VKORC1, is unknown. Here we determined the structural and functional differences of these two enzymes using fluorescence protease protection (FPP) assay and an in vivo cell-based activity assay. We show that in vivo VKORC1L1 reduces vitamin K epoxide to support vitamin K-dependent carboxylation as efficiently as does VKORC1. However, FPP assays show that unlike VKORC1, VKORC1L1 is a four-transmembrane domain protein with both its termini located in the cytoplasm. Moreover, the conserved loop cysteines, which are not required for VKORC1 activity, are essential for VKORC1L1's active site regeneration. Results from domain exchanges between VKORC1L1 and VKORC1 suggest that it is VKORC1L1's overall structure that uniquely allows for active site regeneration by the conserved loop cysteines. Intermediate disulfide trapping results confirmed an intra-molecular electron transfer pathway for VKORC1L1's active site reduction. Our results allow us to propose a concerted action of the four conserved cysteines of VKORC1L1 for active site regeneration; the second loop cysteine, Cys-58, attacks the active site disulfide, forming an intermediate disulfide with Cys-139; the first loop cysteine, Cys-50, attacks the intermediate disulfide resulting in active site reduction. The different membrane topologies and reaction mechanisms between VKORC1L1 and VKORC1 suggest that these two proteins might have different physiological functions.
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Affiliation(s)
- Jian-Ke Tie
- From the Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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Müller E, Keller A, Fregin A, Müller CR, Rost S. Confirmation of warfarin resistance of naturally occurring VKORC1 variants by coexpression with coagulation factor IX and in silico protein modelling. BMC Genet 2014; 15:17. [PMID: 24491178 PMCID: PMC3927768 DOI: 10.1186/1471-2156-15-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 01/31/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND VKORC1 has been identified some years ago as the gene encoding vitamin K epoxide reductase (VKOR) - the target protein for coumarin derivates like warfarin or phenprocoumon. Resistance against warfarin and other coumarin-type anticoagulants has been frequently reported over the last 50 years in rodents due to problems in pest control as well as in thrombophilic patients showing variable response to anticoagulant treatment. Many different mutations have already been detected in the VKORC1 gene leading to warfarin resistance in rats, mice and in humans. Since the conventional in vitro dithiothreitol (DTT)-driven VKOR enzymatic assay often did not reflect the in vivo status concerning warfarin resistance, we recently developed a cell culture-based method for coexpression of VKORC1 with coagulation factor IX and subsequent measurement of secreted FIX in order to test warfarin inhibition in wild-type and mutated VKORC1. RESULTS In the present study, we coexpressed wild-type factor IX with 12 different VKORC1 variants which were previously detected in warfarin resistant rats and mice. The results show that amino acid substitutions in VKORC1 maintain VKOR activity and are associated with warfarin resistance. When we projected in silico the amino acid substitutions onto the published three-dimensional model of the bacterial VKOR enzyme, the predicted effects matched well the catalytic mechanism proposed for the bacterial enzyme. CONCLUSIONS The established cell-based system for coexpression of VKORC1 and factor IX uses FIX activity as an indicator of carboxylation efficiency. This system reflects the warfarin resistance status of VKORC1 mutations from anticoagulant resistant rodents more closely than the traditional DTT-driven enzyme assay. All mutations studied were also predicted to be involved in the reaction mechanism.
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Affiliation(s)
| | | | | | | | - Simone Rost
- Department of Human Genetics, University of Würzburg, Würzburg, Germany.
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A cellular system for quantitation of vitamin K cycle activity: structure-activity effects on vitamin K antagonism by warfarin metabolites. Blood 2013; 123:582-9. [PMID: 24297869 DOI: 10.1182/blood-2013-05-505123] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Warfarin and other 4-hydroxycoumarins inhibit vitamin K epoxide reductase (VKOR) by depleting reduced vitamin K that is required for posttranslational modification of vitamin K-dependent clotting factors. In vitro prediction of the in vivo potency of vitamin K antagonists is complicated by the complex multicomponent nature of the vitamin K cycle. Here we describe a sensitive assay that enables quantitative analysis of γ-glutamyl carboxylation and its antagonism in live cells. We engineered a human embryonic kidney (HEK) 293-derived cell line (HEK 293-C3) to express a chimeric protein (F9CH) comprising the Gla domain of factor IX fused to the transmembrane and cytoplasmic regions of proline-rich Gla protein 2. Maximal γ-glutamyl carboxylation of F9CH required vitamin K supplementation, and was dose-dependently inhibited by racemic warfarin at a physiologically relevant concentration. Cellular γ-glutamyl carboxylation also exhibited differential VKOR inhibition by warfarin enantiomers (S > R) consistent with their in vivo potencies. We further analyzed the structure-activity relationship for inhibition of γ-glutamyl carboxylation by warfarin metabolites, observing tolerance to phenolic substitution at the C-5 and especially C-6, but not C-7 or C-8, positions on the 4-hydroxycoumarin nucleus. After correction for in vivo concentration and protein binding, 10-hydroxywarfarin and warfarin alcohols were predicted to be the most potent inhibitory metabolites in vivo.
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27
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Human VKORC1 mutations cause variable degrees of 4-hydroxycoumarin resistance and affect putative warfarin binding interfaces. Blood 2013; 122:2743-50. [PMID: 23982176 DOI: 10.1182/blood-2013-05-501692] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Since the discovery of warfarin-sensitive vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1), 26 human VKORC1 (hVKORC1) missense mutations have been associated with oral anticoagulant resistance (OACR). Assessment of warfarin resistance using the "classical" dithiothreitol-driven vitamin K 2,3-epoxide reductase (VKOR) assay has not reflected clinical resistance phenotypes for most mutations. Here, we present half maximal inhibitory concentrations (IC50) results for 21 further hVKORC1 mutations obtained using a recently validated cell-based assay (J Thromb Haemost 11(5):872). In contrast to results from the dithiothreitol-driven VKOR assay, all mutations exhibited basal VKOR activity and warfarin IC50 values that correspond well to patient OACR phenotypes. Thus, the present assay is useful for functional investigations of VKORC1 and oral anticoagulant inhibition of the vitamin K cycle. Additionally, we modeled hVKORC1 on the previously solved structure of a homologous bacterial enzyme and performed in silico docking of warfarin on this model. We identified one binding site delineated by 3 putative binding interfaces. These interfaces comprise linear sequences of the endoplasmic reticulum-lumenal loop (Ser52-Phe55) and the first (Leu22-Lys30) and fourth (Phe131-Thr137) transmembrane helices. All known OACR-associated hVKORC1 mutations are located in or around these putative interfaces, supporting our model.
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28
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Tie JK, Jin DY, Tie K, Stafford DW. Evaluation of warfarin resistance using transcription activator-like effector nucleases-mediated vitamin K epoxide reductase knockout HEK293 cells. J Thromb Haemost 2013; 11:1556-64. [PMID: 23710884 PMCID: PMC3745541 DOI: 10.1111/jth.12306] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 05/24/2013] [Indexed: 12/31/2022]
Abstract
BACKGROUND Single nucleotide polymorphisms in the vitamin K epoxide reductase (VKOR) gene have been successfully used for warfarin dosage prediction. However, warfarin resistance studies of naturally occurring VKOR mutants do not correlate with their clinical phenotype. This discrepancy presumably arises because the in vitro VKOR activity assay is performed under artificial conditions using the non-physiological reductant dithiothreitol. OBJECTIVES The aim of this study is to establish an in vivo VKOR activity assay in mammalian cells (HEK293) where VKOR functions in its native milieu without interference from endogenous enzymes. METHODS Endogenous VKOR activity in HEK293 cells was knocked out by transcription activator-like effector nucleases (TALENs)-mediated genome editing. RESULTS AND CONCLUSIONS Knockout of VKOR in HEK293 cells significantly decreased vitamin K-dependent carboxylation with vitamin K epoxide (KO) as substrate. However, the paralog of VKOR, VKORC1L1, also exhibits substantial ability to convert KO to vitamin K for carboxylation. Using both VKOR and VKORC1L1 knockout cells, we examined the enzymatic activity and warfarin resistance of 10 naturally occurring VKOR mutants that were reported previously to have no activity in an in vitro assay. All 10 mutants are fully active; five have increased warfarin resistance, with the order being W59R>L128R≈W59L>N77S≈S52L. Except for the L128R mutant, this order is consistent with the clinical anticoagulant dosages. The other five VKOR mutants do not change VKOR's warfarin sensitivity, suggesting that factors other than VKOR play important roles. In addition, we confirmed that the conserved loop cysteines in VKOR are not required for active site regeneration after each cycle of oxidation.
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Affiliation(s)
- J-K Tie
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Determination of the warfarin inhibition constant Ki for vitamin K 2,3-epoxide reductase complex subunit-1 (VKORC1) using an in vitro DTT-driven assay. Biochim Biophys Acta Gen Subj 2013; 1830:4202-10. [PMID: 23618698 DOI: 10.1016/j.bbagen.2013.04.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/12/2013] [Accepted: 04/15/2013] [Indexed: 11/23/2022]
Abstract
BACKGROUND Warfarin directly inhibits vitamin K 2,3-epoxide reductase (VKOR) enzymes. Since the early 1970s, warfarin inhibition of vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1), an essential enzyme for proper function of blood coagulation in higher vertebrates, has been studied using an in vitro dithiothreitol (DTT) driven enzymatic assay. However, various studies based on this assay have reported warfarin dose-response data, usually summarized as half-maximal inhibitory concentration (IC50), that vary over orders of magnitude and reflect the broad range of conditions used to obtain VKOR assay data. METHODS We standardized the implementation of the DTT-driven VKOR activity assay to measure enzymatic Michaelis constants (Km) and warfarin IC50 for human VKORC1. A data transformation is defined, based on the previously confirmed bi bi ping-pong mechanism for VKORC1, that relates assay condition-dependent IC50 to condition-independent Ki. RESULTS Determination of the warfarin Ki specifically depends on measuring both substrate concentrations, both Michaelis constants for the VKORC1 enzyme, and pH in the assay. CONCLUSION The Ki is not equal to the IC50 value directly measured using the DTT-driven VKOR assay. GENERAL SIGNIFICANCE In contrast to warfarin IC50 values determined in previous studies, warfarin inhibition expressed as Ki can now be compared between studies, even when the specific DTT-driven VKOR assay conditions differ. This implies that warfarin inhibition reported for wild-type and variant VKORC1 enzymes from previous reports should be reassessed and new determinations of Ki are required to accurately report and compare in vitro warfarin inhibition results.
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