1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Pratt VM, Cavallari LH, Del Tredici AL, Hachad H, Ji Y, Kalman LV, Ly RC, Moyer AM, Scott SA, Whirl-Carrillo M, Weck KE. Recommendations for Clinical Warfarin Genotyping Allele Selection: A Report of the Association for Molecular Pathology and the College of American Pathologists. J Mol Diagn 2020; 22:847-859. [PMID: 32380173 DOI: 10.1016/j.jmoldx.2020.04.204] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 03/18/2020] [Accepted: 04/01/2020] [Indexed: 11/19/2022] Open
Abstract
The goal of the Association for Molecular Pathology (AMP) Clinical Practice Committee's AMP Pharmacogenomics (PGx) Working Group is to define the key attributes of PGx alleles recommended for clinical testing and a minimum set of variants that should be included in clinical PGx genotyping assays. This document series provides recommendations for a minimum panel of variant alleles (tier 1) and an extended panel of variant alleles (tier 2) that will aid clinical laboratories when designing assays for PGx testing. The AMP PGx Working Group considered functional impact of the variants, allele frequencies in multiethnic populations, the availability of reference materials, as well as other technical considerations for PGx testing when developing these recommendations. The ultimate goal is to promote standardization of PGx gene/allele testing across clinical laboratories. These recommendations are not to be interpreted as prescriptive but to provide a reference guide. Of note, a separate article with recommendations for CYP2C9 allele selection was previously developed by the PGx Working Group that can be applied broadly to CYP2C9-related medications. The warfarin allele recommendations in this report incorporate the previous CYP2C9 allele recommendations and additional genes and alleles that are specific to warfarin testing.
Collapse
Affiliation(s)
- Victoria M Pratt
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana.
| | - Larisa H Cavallari
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Pharmacotherapy and Translational Research and Center for Pharmacogenomics and Precision Medicine, University of Florida, Gainesville, Florida
| | - Andria L Del Tredici
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Millennium Health, LLC, San Diego, California
| | - Houda Hachad
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Translational Software, Bellevue, Washington
| | - Yuan Ji
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Pathology and ARUP Laboratories, University of Utah School of Medicine, Salt Lake City, Utah
| | - Lisa V Kalman
- Division of Laboratory Systems, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Reynold C Ly
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ann M Moyer
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Stuart A Scott
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York; Sema4, a Mount Sinai venture, Stamford, Connecticut
| | - Michelle Whirl-Carrillo
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Department of Biomedical Data Science, Stanford University, Stanford, California
| | - Karen E Weck
- The Pharmacogenomics Working Group of the Clinical Practice Committee, Association for Molecular Pathology, Rockville, Maryland; Departments of Pathology and Laboratory Medicine and Genetics, University of North Carolina, Chapel Hill, North Carolina
| |
Collapse
|
3
|
Goulois J, Lambert V, Legros L, Benoit E, Lattard V. Adaptative evolution of the Vkorc1 gene in Mus musculus domesticus is influenced by the selective pressure of anticoagulant rodenticides. Ecol Evol 2017; 7:2767-2776. [PMID: 28428867 PMCID: PMC5395456 DOI: 10.1002/ece3.2829] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 01/15/2017] [Accepted: 01/28/2017] [Indexed: 11/24/2022] Open
Abstract
Anticoagulant rodenticides are commonly used to control rodent pests worldwide. They specifically inhibit the vitamin K epoxide reductase (VKORC1), which is an enzyme encoded by the Vkorc1 gene, involved in the recycling of vitamin K. Therefore, they prevent blood clotting. Numerous mutations of Vkorc1 gene were reported in rodents, and some are involved in the resistant to rodenticides phenotype. Two hundred and sixty‐six mice tails were received from 65 different locations in France. Coding sequences of Vkorc1 gene were sequenced in order to detect mutations. Consequences of the observed mutations were evaluated by the use of recombinant VKORC1. More than 70% of mice presented Vkorc1 mutations. Among these mice, 80% were homozygous. Contrary to brown rats for which only one predominant Vkorc1 genotype was found in France, nine missense single mutations and four double mutations were observed in house mice. The single mutations lead to resistance to first‐generation antivitamin K (AVKs) only and are certainly associated with the use of these first‐generation molecules by nonprofessionals for the control of mice populations. The double mutations, probably obtained by genetic recombination, lead to in vitro resistance to all AVKs. They must be regarded as an adaptive evolution to the current use of second‐generation AVKs. The intensive use of first‐generation anticoagulants probably allowed the selection of a high diversity of mutations, which makes possible the genetic recombination and consequently provokes the emergence of the more resistant mutated Vkorc1 described to date.
Collapse
Affiliation(s)
- Joffrey Goulois
- USC 1233 RS2GPVetAgro Sup, INRA, Univ LyonF‐69280MARCY L’ETOILEFrance
- Liphatech, BonnelPont du CasseFrance
| | - Véronique Lambert
- USC 1233 RS2GPVetAgro Sup, INRA, Univ LyonF‐69280MARCY L’ETOILEFrance
| | | | - Etienne Benoit
- USC 1233 RS2GPVetAgro Sup, INRA, Univ LyonF‐69280MARCY L’ETOILEFrance
| | - Virginie Lattard
- USC 1233 RS2GPVetAgro Sup, INRA, Univ LyonF‐69280MARCY L’ETOILEFrance
| |
Collapse
|
4
|
Freyburger G, Labrouche S, Hubert C, Bauduer F. Haemostaseome-associated SNPs: has the thrombotic phenotype a greater influence than ethnicity? GMT study from Aquitaine including Basque individuals. Thromb Haemost 2014; 113:66-76. [PMID: 25374097 DOI: 10.1160/th14-02-0189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 08/15/2014] [Indexed: 11/05/2022]
Abstract
The Genetic Markers for Thrombosis (GMT) study compared the relative influence of ethnicity and thrombotic phenotype regarding the distribution of SNPs implicated in haemostasis pathophysiology ("haemostaseome"). We assessed 384 SNPs in three groups, each of 480 subjects: 1) general population of Aquitaine region (Southwestern France) used as control; 2) patients with venous thromboembolism from the same area; and 3) autochthonous Basques, a genetic isolate, who demonstrate unusual characteristics regarding the coagulation system. This study sought to evaluate i) the value of looking for a large number of genes in order to identify new genetic markers of thrombosis, ii) the value of investigating low risk factors and potential preferential associations, iii) the impact of ethnicity on the characterisation of markers for thrombosis. We did not detect any previously unrecognised SNP significantly associated with thrombosis risk or any preferential associations of low-risk factors in patients with thrombosis. The sum of ϰ² values for our 110 significant SNPs demonstrated a smaller genetic distance between patients and controls (321 cumulated ϰ² value) than between Basques and controls (1,570 cumulated ϰ² value). Hence, our study confirms the genetic particularity of Basques especially regarding a significantly lower expression of the non-O blood group (p< 0.0004). This is mitigated by a higher prevalence of factor II Leiden (p< 0.02) while factor V Leiden prevalence does not differ. Numerous other differences covering a wide range of proteins of the haemostaseome may result in an overall different genetic risk for venous thromboembolism.
Collapse
Affiliation(s)
- Geneviève Freyburger
- Geneviève Freyburger, Laboratory for Hematology, CHU Pellegrin, 33076 Bordeaux cedex, France, Tel.: +335 57 820 206, Fax: +335 56 79 60 20, E-mail:
| | | | | | | |
Collapse
|
5
|
Oldenburg J, Müller CR, Rost S, Watzka M, Bevans CG. Comparative genetics of warfarin resistance. Hamostaseologie 2013; 34:143-59. [PMID: 24287886 DOI: 10.5482/hamo-13-09-0047] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 09/25/2013] [Indexed: 11/05/2022] Open
Abstract
Warfarin and other 4-hydroxycoumarin-based oral anticoagulants targeting vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) are administered to humans, mice and rats with different purposes in mind - to act as pesticides in high-dosage baits for killing rodents, but also to save lives when administered in low dosages as antithrombotic drugs in humans. However, high-dosage warfarin used to control rodent populations has resulted in numerous mutations causing warfarin resistance. Currently, six single missense mutations in mice, 12 distinct missense mutations in rats, as well as compound heterozygous or homozygous mutations with up to six distinct missense mutations per Vkorc1 allele have been described. Warfarin resistance missense mutations for human VKORC1 have also been found world-wide, but differ characteristically from those in rodents. In humans, 26 distinct mutations have been characterized, but occur only rarely either in heterozygous or, even rarer, in homozygous form. In this review, we summarize the known VKORC1 missense mutations causing warfarin and other 4-hydroxycoumarin drug resistance, identify genomics databases as new sources of data, explore possible underlying genetic mechanisms, and summarize similarities and differences between warfarin resistant VKORC1 variants in humans and rodents.
Collapse
Affiliation(s)
- J Oldenburg
- Prof. Dr. Johannes Oldenburg, Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Sigmund Freud Str. 25, 53105 Bonn, Germany, E-mail: , Tel. +49/(0)228/287 51 75, Fax +49/(0)228/287 51 76
| | | | | | | | | |
Collapse
|
6
|
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.
Collapse
|
7
|
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.
Collapse
Affiliation(s)
- J-K Tie
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | | | | | | |
Collapse
|
8
|
Hodroge A, Matagrin B, Moreau C, Fourel I, Hammed A, Benoit E, Lattard V. VKORC1 mutations detected in patients resistant to vitamin K antagonists are not all associated with a resistant VKOR activity. J Thromb Haemost 2012; 10:2535-43. [PMID: 23039877 DOI: 10.1111/jth.12019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND The VKORC1 gene codes for the VKORC1 enzyme, which is responsible for the reduction of vitamin K epoxide into vitamin K. VKORC1 enzyme is the target of vitamin K antagonists (VKA). Twenty-eight rare single mutations in the VKORC1 coding sequence have been reported from resistant patients receiving unusually high doses of VKA to achieve therapeutic anticoagulation. OBJECTIVES It has been suggested that these mutations are responsible for the resistant phenotype, while biochemical consequences of these mutations on the VKORC1 enzyme have not yet been evaluated. Therefore, the aim of this study was to investigate the causality of the VKORC1 mutations in the resistance phenotype. METHODS Wild-type VKORC1 and its spontaneous mutants were expressed in Pichia pastoris and susceptibility to VKA was assessed by the in vitro determination of kinetic and inhibition constants. RESULTS AND CONCLUSIONS The in vitro analysis revealed that six mutations only (A26P, A41S, V54L, H68Y, I123N and Y139H) were associated with increase in K(i) , suggesting their involvement in the resistance phenotype observed in patients. A41S and H68Y led to selective resistance, respectively, to indane-1,3-dione and 4-hydroxycoumarine derivatives. The other mutations did not increase the K(i). Furthermore, 10 mutations (S52L, S52W, W59L, W59R, V66M, V66G, G71A, N77S, N77T and L128R) led to an almost complete loss of activity. These results suggest the existence of other resistance mechanisms.
Collapse
Affiliation(s)
- A Hodroge
- USC 1233 INRA-Vetagro Sup, Veterinary School of Lyon, 69280 Marcy l'Etoile, France
| | | | | | | | | | | | | |
Collapse
|
9
|
Burmester JK, Berg RL, Glurich I, Yale SH, Schmelzer JR, Caldwell MD. Absence of novel CYP4F2 and VKORC1 coding region DNA variants in patients requiring high warfarin doses. Clin Med Res 2011; 9:119-24. [PMID: 21562135 PMCID: PMC3251364 DOI: 10.3121/cmr.2011.951] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Warfarin is an FDA-approved oral anticoagulant for long-term prevention of thromboembolism. Substantial inter-individual variation in dosing requirements and the narrow therapeutic index of this widely-prescribed drug make safe initiation and dose stabilization challenging. Single nucleotide polymorphisms (SNPs) occurring in CYP2C9, VKORC1, and CYP4F2 genes are known to impact dose, and VKORC1 and CYP4F2 polymorphisms are associated with higher therapeutic dose requirements in our cohort. However, the most advanced regression models using personal, clinical, and genetic factors to predict individual stable dose account for only 50% to 60% of the observed variability in stable therapeutic dose in Caucasians. DESIGN AND METHODS In this study, we used DNA sequence analysis to determine whether additional variants in CYP4F2 and VKORC1 gene coding regions contribute to variable dosing requirements among individuals for whom the actual dose was the highest relative to regression model- predicted dose. RESULTS AND CONCLUSIONS No novel DNA variants in the coding regions of these genes were identified among subjects requiring high warfarin doses, suggesting that other factors yet to be defined contribute to variability in warfarin dose requirements in this subset of our cohort.
Collapse
Affiliation(s)
- James K Burmester
- Center for Human Genetics, Marshfield Clinic Research Foundation, Marshfield, WI 54449, USA.
| | | | | | | | | | | |
Collapse
|
10
|
Wu S, Liu S, Davis CH, Stafford DW, Kulman JD, Pedersen LG. A hetero-dimer model for concerted action of vitamin K carboxylase and vitamin K reductase in vitamin K cycle. J Theor Biol 2011; 279:143-9. [PMID: 21453708 DOI: 10.1016/j.jtbi.2011.03.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 03/23/2011] [Accepted: 03/23/2011] [Indexed: 10/18/2022]
Abstract
Vitamin K carboxylase (VKC) is believed to convert vitamin K, in the vitamin K cycle, to an alkoxide-epoxide form which then reacts with CO(2) and glutamate to generate γ-carboxyglutamic acid (Gla). Subsequently, vitamin K epoxide reductase (VKOR) is thought to convert the alkoxide-epoxide to a hydroquinone form. By recycling vitamin K, the two integral-membrane proteins, VKC and VKOR, maintain vitamin K levels and sustain the blood coagulation cascade. Unfortunately, NMR or X-ray crystal structures of the two proteins have not been characterized. Thus, our understanding of the vitamin K cycle is only partial at the molecular level. In this study, based on prior biochemical experiments on VKC and VKOR, we propose a hetero-dimeric form of VKC and VKOR that may explain the efficient oxidation and reduction of vitamin K during the vitamin K cycle.
Collapse
Affiliation(s)
- Sangwook Wu
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, USA
| | | | | | | | | | | |
Collapse
|
11
|
Watzka M, Geisen C, Bevans CG, Sittinger K, Spohn G, Rost S, Seifried E, Müller CR, Oldenburg J. Thirteen novel VKORC1 mutations associated with oral anticoagulant resistance: insights into improved patient diagnosis and treatment. J Thromb Haemost 2011; 9:109-18. [PMID: 20946155 DOI: 10.1111/j.1538-7836.2010.04095.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND Vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) is the molecular target of oral anticoagulants. Mutations in VKORC1 cause partial or total coumarin resistance. OBJECTIVES To identify new VKORC1 oral anticoagulant (OAC) resistance (OACR) mutations and compare the severity of patient phenotypes across different mutations and prescribed OAC drugs. PATIENTS/METHODS Six hundred and twenty-six individuals exhibiting partial or complete coumarin resistance were analyzed by VKORC1 gene sequencing and CYP2C9 haplotyping. RESULTS We identified 13 patients, each with a different, novel human VKORC1 heterozygous mutation associated with an OACR phenotype. These mutations result in amino acid substitutions: Ala26→Thr, His28→Gln, Asp36→Gly, Ser52→Trp, Ser56→Phe, Trp59→Leu, Trp59→Cys, Val66→Gly, Gly71→Ala, Asn77→Ser, Asn77→Tyr, Ile123→Asn, and Tyr139→His. Ten additional patients each had one of three previously reported VKORC1 mutations (Val29→Leu, Asp36→Tyr, and Val66→Met). Genotyping of frequent VKORC1 and CYP2C9 polymorphisms in these patients revealed a predominant association with combined non-VKORC1*2 and wild-type CYP2C9 haplotypes. Additionally, data for OAC dosage and the associated measured International Normalized Ratio (INR) demonstrate that OAC therapy is often discontinued by physicians, although stable therapeutic INR levels may be reached at higher OAC dosages. Bioinformatic analysis of VKORC1 homologous protein sequences indicated that most mutations cluster into protein sequence segments predicted to be localized in the lumenal loop or at the endoplasmic reticulum membrane-lumen interface. CONCLUSIONS OACR mutations of VKORC1 predispose afflicted patients to high OAC dosage requirements, for which stable, therapeutic INRs can sometimes be attained.
Collapse
Affiliation(s)
- M Watzka
- Institute of Experimental Hematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Rishavy MA, Usubalieva A, Hallgren KW, Berkner KL. Novel insight into the mechanism of the vitamin K oxidoreductase (VKOR): electron relay through Cys43 and Cys51 reduces VKOR to allow vitamin K reduction and facilitation of vitamin K-dependent protein carboxylation. J Biol Chem 2010; 286:7267-78. [PMID: 20978134 DOI: 10.1074/jbc.m110.172213] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The vitamin K oxidoreductase (VKOR) reduces vitamin K to support the carboxylation and consequent activation of vitamin K-dependent proteins, but the mechanism of reduction is poorly understood. VKOR is an integral membrane protein that reduces vitamin K using membrane-embedded thiols (Cys-132 and Cys-135), which become oxidized with concomitant VKOR inactivation. VKOR is subsequently reactivated by an unknown redox protein that is currently thought to act directly on the Cys132-Cys135 residues. However, VKOR contains evolutionarily conserved Cys residues (Cys-43 and Cys-51) that reside in a loop outside of the membrane, raising the question of whether they mediate electron transfer from a redox protein to Cys-132/Cys-135. To assess a possible role, the activities of mutants with Ala substituted for Cys (C43A and C51A) were analyzed in intact membranes using reductants that were either membrane-permeable or -impermeable. Both reductants resulted in wild type VKOR reduction of vitamin K epoxide; however, the C43A and C51A mutants only showed activity with the membrane-permeant reductant. We obtained similar results when testing the ability of wild type and mutant VKORs to support carboxylation, using intact membranes from cells coexpressing VKOR and carboxylase. These results indicate a role for Cys-43 and Cys-51 in catalysis, suggesting a relay mechanism in which a redox protein transfers electrons to these loop residues, which in turn reduce the membrane-embedded Cys132-Cys135 disulfide bond to activate VKOR. The results have implications for the mechanism of warfarin resistance, the topology of VKOR in the membrane, and the interaction of VKOR with the carboxylase.
Collapse
Affiliation(s)
- Mark A Rishavy
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
| | | | | | | |
Collapse
|
13
|
Orsi FA, Annichino Bizzacchi JM, de Paula EV, Ozelo MC, Langley MR, Weck KE. VKORC1 V66M mutation in African Brazilian patients resistant to oral anticoagulant therapy. Thromb Res 2010; 126:e206-10. [PMID: 20615525 DOI: 10.1016/j.thromres.2010.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 05/12/2010] [Accepted: 06/07/2010] [Indexed: 11/28/2022]
Abstract
Warfarin-based anticoagulant therapy is associated with large variability in dose response. Genetic variability in the VKORC1 and CYP2C9 genes is associated with increased warfarin sensitivity. In addition, rare coding region mutations in VKORC1 have been associated with resistance to warfarin. VKORC1 and CYP2C9 variability associated with altered warfarin response is less well characterized in African and mixed-raced populations such as Brazilians. To determine genetic variability associated with altered warfarin response among Brazilian patients, sixty-two adult patients with extreme resistance or sensitivity to warfarin were genotyped for variants in CYP2C9 and VKORC1. Of the 51 patients on low doses of warfarin, the VKORC1--1639 (3673) G>A polymorphism associated with warfarin sensitivity was present in 48 (94.1%), including 97% of Caucasians, 82% of African-descent patients, and all 7 (100%) patients of Indian descent. Additionally, 52.9% of warfarin sensitive patients had at least one CYP2C9*2 or CYP2C9*3 decreased metabolism allele, 63.6% of Caucasians and 54% of African-descent patients. Of the 11 patients on high doses of warfarin, sequencing of VKORC1 revealed a nonsynonymous V66M mutation in two warfarin resistant patients, both of African-descent. Brazilian patients requiring low doses of warfarin have a high frequency of VKORC1 and CYP2C9 variants associated with warfarin sensitivity. The presence of the rare VKORC1 V66M in two warfarin high dose outlier patients implies that this variant may be more frequent among African Brazilians and has implications for future warfarin studies in other populations of African descent.
Collapse
Affiliation(s)
- Fernanda A Orsi
- Hematology and Hemotherapy Center, State University of Campinas, Brazil.
| | | | | | | | | | | |
Collapse
|
14
|
Stepien E, Branicka A, Ciesla-Dul M, Undas A. A vitamin K epoxide reductase-oxidase complex gene polymorphism (-1639G>A) and interindividual variability in the dose-effect of vitamin K antagonists. J Appl Genet 2010; 50:399-403. [PMID: 19875892 DOI: 10.1007/bf03195700] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A daily dose of vitamin K antagonists (VKAs) may vary and its range depends on various interrelated factors. Low responsiveness to VKA (defined as a failure to achieve a target international normalized ratio [INR]) is associated with polymorphisms of the vitamin K epoxide reductase-oxidase complex gene (VKORC1). A highly prevalent promoter single-nucleotide polymorphism (VKORC1-1639 G>A, rs17878363) impairs VKORC1 expression and determines the interindividual variability of the target INR. We studied 57 patients receiving oral anticoagulation, including 50 subjects treated with acenocoumarol (mean dose: 5.7+/-2.3 mg/day) and 7 treated with warfarin (mean dose: 9.6+/-4.2 mg/day). The indications for the use of oral anticoagulant therapy were as follows: deep-vein thrombosis (N = 23); pulmonary embolism (N = 20); arterial thrombosis (N = 5); stroke (N = 4); atrial fibrillation with transient ischemic attacks (N = 2), and history of multiple thromboembolic events (N = 3). Identification of the VKORC1 genomic variation was performed using DNA sequencing methods. The prevalence of the mutated allele (VKORC1 -1639A) was 41%. The VKORC1 -1639G allele carriers required a higher daily dose of acenocoumarol (5.9+/-1.9 mg) than the noncarriers (4.1+/-3.3 mg; P < 0.001). All of 5 low responders (who failed to achieve a target INR using standard dose requirements of VKAs) were homozygous for the 1639G allele. Low responders did not differ from good responders with respect to age, gender, and body mass index. Our findings suggest the potential benefits from pharmacogenetic testing, and provide evidence that the VKORC1 -1639 G>A gene polymorphism may explain at least in part the low responsiveness to acenocoumarol.
Collapse
Affiliation(s)
- E Stepien
- John Paul II Hospital, Krakow, Poland.
| | | | | | | |
Collapse
|
15
|
Schmeits PCJ, Hermans MHA, van Geest-Daalderop JHH, Poodt J, de Sauvage Nolting PRW, Conemans JMH. VKORC1mutations in patients with partial resistance to phenprocoumon. Br J Haematol 2010; 148:955-7. [DOI: 10.1111/j.1365-2141.2009.08017.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
16
|
Peoc’h K, Pruvot S, Gourmel C, dit Sollier CB, Drouet L. A newVKORC1mutation leading to an isolated resistance to fluindione. Br J Haematol 2009; 145:841-3. [DOI: 10.1111/j.1365-2141.2009.07687.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
17
|
Langley MR, Booker JK, Evans JP, McLeod HL, Weck KE. Validation of clinical testing for warfarin sensitivity: comparison of CYP2C9-VKORC1 genotyping assays and warfarin-dosing algorithms. J Mol Diagn 2009; 11:216-25. [PMID: 19324988 DOI: 10.2353/jmoldx.2009.080123] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Responses to warfarin (Coumadin) anticoagulation therapy are affected by genetic variability in both the CYP2C9 and VKORC1 genes. Validation of pharmacogenetic testing for warfarin responses includes demonstration of analytical validity of testing platforms and of the clinical validity of testing. We compared four platforms for determining the relevant single nucleotide polymorphisms (SNPs) in both CYP2C9 and VKORC1 that are associated with warfarin sensitivity (Third Wave Invader Plus, ParagonDx/Cepheid Smart Cycler, Idaho Technology LightCycler, and AutoGenomics Infiniti). Each method was examined for accuracy, cost, and turnaround time. All genotyping methods demonstrated greater than 95% accuracy for identifying the relevant SNPs (CYP2C9 *2 and *3; VKORC1 -1639 or 1173). The ParagonDx and Idaho Technology assays had the shortest turnaround and hands-on times. The Third Wave assay was readily scalable to higher test volumes but had the longest hands-on time. The AutoGenomics assay interrogated the largest number of SNPs but had the longest turnaround time. Four published warfarin-dosing algorithms (Washington University, UCSF, Louisville, and Newcastle) were compared for accuracy for predicting warfarin dose in a retrospective analysis of a local patient population on long-term, stable warfarin therapy. The predicted doses from both the Washington University and UCSF algorithms demonstrated the best correlation with actual warfarin doses.
Collapse
Affiliation(s)
- Michael R Langley
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7525, USA
| | | | | | | | | |
Collapse
|
18
|
Bodin L, Perdu J, Diry M, Horellou MH, Loriot MA. Multiple genetic alterations in vitamin K epoxide reductase complex subunit 1 gene (VKORC1) can explain the high dose requirement during oral anticoagulation in humans. J Thromb Haemost 2008; 6:1436-9. [PMID: 18532998 DOI: 10.1111/j.1538-7836.2008.03049.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|