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Ghosh S, Oldenburg J, Czogalla-Nitsche KJ. The Role of GRP and MGP in the Development of Non-Hemorrhagic VKCFD1 Phenotypes. Int J Mol Sci 2022; 23:798. [PMID: 35054981 PMCID: PMC8775833 DOI: 10.3390/ijms23020798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/05/2022] [Accepted: 01/08/2022] [Indexed: 11/21/2022] Open
Abstract
Vitamin K dependent coagulation factor deficiency type 1 (VKCFD1) is a rare hereditary bleeding disorder caused by mutations in γ-Glutamyl carboxylase (GGCX) gene. The GGCX enzyme catalyzes the γ-carboxylation of 15 different vitamin K dependent (VKD) proteins, which have function in blood coagulation, calcification, and cell signaling. Therefore, in addition to bleedings, some VKCFD1 patients develop diverse non-hemorrhagic phenotypes such as skin hyper-laxity, skeletal dysmorphologies, and/or cardiac defects. Recent studies showed that GGCX mutations differentially effect γ-carboxylation of VKD proteins, where clotting factors are sufficiently γ-carboxylated, but not certain non-hemostatic VKD proteins. This could be one reason for the development of diverse phenotypes. The major manifestation of non-hemorrhagic phenotypes in VKCFD1 patients are mineralization defects. Therefore, the mechanism of regulation of calcification by specific VKD proteins as matrix Gla protein (MGP) and Gla-rich protein (GRP) in physiological and pathological conditions is of high interest. This will also help to understand the patho-mechanism of VKCFD1 phenotypes and to deduce new treatment strategies. In the present review article, we have summarized the recent findings on the function of GRP and MGP and how these proteins influence the development of non-hemorrhagic phenotypes in VKCFD1 patients.
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Affiliation(s)
- Suvoshree Ghosh
- Institute of Experimental Haematology and Transfusion Medicine, Venusberg Campus 1, University Clinic Bonn, 53127 Bonn, Germany; (S.G.); (J.O.)
| | - Johannes Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine, Venusberg Campus 1, University Clinic Bonn, 53127 Bonn, Germany; (S.G.); (J.O.)
- Center for Rare Diseases Bonn, Venusberg Campus 1, University Clinic Bonn, 53127 Bonn, Germany
| | - Katrin J. Czogalla-Nitsche
- Institute of Experimental Haematology and Transfusion Medicine, Venusberg Campus 1, University Clinic Bonn, 53127 Bonn, Germany; (S.G.); (J.O.)
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Ghosh S, Kraus K, Biswas A, Müller J, Forin F, Singer H, Höning K, Hornung V, Watzka M, Oldenburg J, Czogalla-Nitsche KJ. GGCX variants leading to biallelic deficiency to γ-carboxylate GRP cause skin laxity in VKCFD1 patients. Hum Mutat 2021; 43:42-55. [PMID: 34816548 DOI: 10.1002/humu.24300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 09/06/2021] [Accepted: 10/19/2021] [Indexed: 12/17/2022]
Abstract
γ-Glutamyl carboxylase (GGCX) catalyzes the γ-carboxylation of 15 different vitamin K dependent (VKD) proteins. Pathogenic variants in GGCX cause a rare hereditary bleeding disorder called Vitamin K dependent coagulation factor deficiency type 1 (VKCFD1). In addition to bleedings, some VKCFD1 patients develop skin laxity and skeletal dysmorphologies. However, the pathophysiological mechanisms underlying these non-hemorrhagic phenotypes remain elusive. Therefore, we have analyzed 20 pathogenic GGCX variants on their ability to γ-carboxylate six non-hemostatic VKD proteins in an in vitro assay, where GGCX variants were expressed in GGCX-/- cells and levels of γ-carboxylated co-expressed VKD proteins were detected by a functional ELISA. We observed that GGCX variants causing markedly reduced γ-carboxylation of Gla rich protein (GRP) in vitro were reported in patients with skin laxity. Reduced levels of γ-carboxylated Matrix gla protein (MGP) are not exclusive for causing skeletal dysmorphologies in VKCFD1 patients. In silico docking of vitamin K hydroquinone on a GGCX model revealed a binding site, which was validated by in vitro assays. GGCX variants affecting this site result in disability to γ-carboxylate VKD proteins and hence are involved in the most severe phenotypes. This genotype-phenotype analysis will help to understand the development of non-hemorrhagic phenotypes and hence improve treatment in VKCFD1 patients.
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Affiliation(s)
- Suvoshree Ghosh
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Katrin Kraus
- 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
| | - Jens Müller
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Francesco Forin
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Heike Singer
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Klara Höning
- Unit for Clinical Biochemistry, Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Bonn, Germany
| | - Veit Hornung
- Unit for Clinical Biochemistry, Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Bonn, Germany.,GeneCenter and Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Matthias Watzka
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany.,Center for Rare Diseases Bonn, University Clinic Bonn, Bonn, Germany
| | - Johannes Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany.,Center for Rare Diseases Bonn, University Clinic Bonn, Bonn, Germany
| | - Katrin J Czogalla-Nitsche
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
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Ghosh S, Kraus K, Biswas A, Müller J, Buhl AL, Forin F, Singer H, Höning K, Hornung V, Watzka M, Czogalla-Nitsche KJ, Oldenburg J. GGCX mutations show different responses to vitamin K thereby determining the severity of the hemorrhagic phenotype in VKCFD1 patients. J Thromb Haemost 2021; 19:1412-1424. [PMID: 33590680 DOI: 10.1111/jth.15238] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/22/2020] [Accepted: 01/04/2021] [Indexed: 01/09/2023]
Abstract
BACKGROUND Vitamin K dependent coagulation factor deficiency type 1 (VKCFD1) is a rare hereditary bleeding disorder caused by mutations in γ-glutamyl carboxylase (GGCX). VKCFD1 patients are treated life-long with high doses of vitamin K in order to correct the bleeding phenotype. However, normalization of clotting factor activities cannot be achieved for all VKCFD1 patients. OBJECTIVE The current study aims to investigate the responsiveness to vitamin K for all reported GGCX mutations with respect to clotting factors in order to optimize treatment. METHODS This study developed an assay using genetically engineered GGCX-/- cells, in which GGCX mutations were analyzed with respect to their ability to γ-carboxylate vitamin K dependent pro-coagulatory and anti-coagulatory clotting factors by ELISA. Additionally, factor VII activity was measured in order to proof protein functionality. For specific GGCX mutations immunofluorescent staining was performed to assess the intracellular localization of clotting factors with respect to GGCX wild-type and mutations. RESULTS All GGCX mutations were categorized into responder and low responder mutations, thereby determining the efficiency of vitamin K supplementation. Most VKCFD1 patients have at least one vitamin K responsive GGCX allele that is able to γ-carboxylate clotting factors. In few patients, the hemorrhagic phenotype cannot be reversed by vitamin K administration because GGCX mutations on both alleles affect either structural or catalytically important sites thereby resulting in residual ability to γ-carboxylate clotting factors. CONCLUSION With these new functional data we can predict the hemorrhagic outcome of each VKCFD1 genotype, thus recommending treatments with either vitamin K or prothrombin complex concentrate.
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Affiliation(s)
- Suvoshree Ghosh
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Katrin Kraus
- 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
| | - Jens Müller
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Anna-Lena Buhl
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Francesco Forin
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Heike Singer
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Klara Höning
- Institute for Clinical Chemistry and Clinical Pharmacology, Unit for Clinical Biochemistry, University Hospital, University of Bonn, Bonn, Germany
| | - Veit Hornung
- Institute for Clinical Chemistry and Clinical Pharmacology, Unit for Clinical Biochemistry, University Hospital, University of Bonn, Bonn, Germany
- GeneCenter and Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Matthias Watzka
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
- Center for Rare Diseases Bonn, University Clinic Bonn, Bonn, Germany
| | - Katrin J Czogalla-Nitsche
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
| | - Johannes Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Bonn, Germany
- Center for Rare Diseases Bonn, University Clinic Bonn, Bonn, Germany
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Dorgalaleh A, Tabibian S, Hosseini MS, Shams M. Pharmacological management of rare coagulation factor deficiencies besides hemophilia. Expert Rev Hematol 2020; 13:811-834. [PMID: 32667216 DOI: 10.1080/17474086.2020.1796622] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Rare coagulation factor deficiencies are less-known disorders with variable effects on the patient's life. Management of such patients is a challenge due to the paucity of evidence-based data, more so when patients with these rare disorders encounter a more rare, related condition, like inhibitor development or thrombosis. AREA COVERED A comprehensive literature search related to RCFDs and management was performed in PubMed in order to discuss therapeutic options and challenges, prophylaxis, management of minor and major surgeries, obstetric and gynecological complications, inhibitor development, and thrombosis. EXPERT OPINION Although significant changes have occurred in the management of RCFDs in recent years, more evidence-based studies besides expert opinion are needed for optimal management.
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Affiliation(s)
- Akbar Dorgalaleh
- Department of Hematology and Blood Transfusion, School of Allied Medicine, Iran University of Medical Sciences , Tehran, Iran
| | - Shadi Tabibian
- Department of Hematology and Blood Transfusion, School of Allied Medicine, Iran University of Medical Sciences , Tehran, Iran.,Iranian Comprehensive Hemophilia Care Center , Tehran, Iran
| | - Maryam Sadat Hosseini
- Department of Hematology and Blood Transfusion, School of Allied Medicine, Shahid Beheshti University of Medical Sciences , Tehran, Iran
| | - Mahmood Shams
- Department of Medical Laboratory, Faculty of Paramedical Sciences, Babol University of Medical Sciences , Babol, Iran
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Al-Doory S, Radaideh M, Saleh S, Al Sabbah M. Congenital Vitamin K-Dependent Clotting Factors Deficiency Type 1: A Rare Bleeding Disorder. DUBAI MEDICAL JOURNAL 2020. [DOI: 10.1159/000506457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Combined deficiency of vitamin K-dependent clotting factors is usually an acquired clinical problem, often resulting from liver disease, malabsorption or warfarin overdose. However, an inherited form of the disease is very rare. Here we report a 4-month-old girl who presented with a 2-week history of multiple bruises and a 1-day history of right thigh swelling after receiving her 4th month vaccine. Laboratory investigations showed anemia (Hb 6.0 g/dL) with extremely prolonged PT and APTT. Factor assay revealed deficiency of vitamin K-dependent clotting factors II, VII, IX, X as well as protein C and protein S. Whole-exome sequencing detected a novel homozygous mutation (c.44-5T>A p.(?)) in the γ-glutamyl carboxylase (GGCX) gene responsible for the autosomal recessive combined vitamin K-dependent clotting factors deficiency type 1.
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6
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Shapiro A. The use of prophylaxis in the treatment of rare bleeding disorders. Thromb Res 2019; 196:590-602. [PMID: 31420204 DOI: 10.1016/j.thromres.2019.07.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 07/02/2019] [Accepted: 07/16/2019] [Indexed: 12/15/2022]
Abstract
Rare bleeding disorders (RBDs) are a heterogeneous group of coagulation factor deficiencies that include fibrinogen, prothrombin, α2-antiplasmin, plasminogen activator inhibitor-1, and factors II, V, V/VIII, VII, X, XI and XIII. The incidence varies based upon the disorder and typically ranges from 1 in 500,000 to 1 per million population. Symptoms vary with the disorder and residual level of the clotting factor, and can range from relatively minor such as epistaxis, to life threatening, such as intracranial hemorrhage. Rapid treatment of bleeding episodes in individuals with severe bleeding phenotypes is essential to preserve life or limb and to prevent long-term sequelae; therapeutic options depend on the deficiency and range from plasma-derived (eg, fresh frozen plasma, prothrombin complex concentrates, factor X concentrate) to highly purified and recombinant single factor concentrates. The rarity of these disorders limits the feasibility of conventional prospective clinical trials; instead, clinicians rely upon registries, published case reports/series and experience to guide treatment. In some disorders, long-term prophylactic therapy is administered in response to the bleeding phenotype in an individual patient or based on the known natural history and severity of the deficiency. Intermittent prophylaxis, surrounding surgery, pregnancy, labor, and menstruation may be required to prevent or control excessive bleeding. This review summarizes therapeutic options, guidelines, recommendations and observations from the published literature for long-term, surgical, gynecological, and obstetric prophylaxis in deficiencies of fibrinogen; prothrombin; factors II, V, V/VIII, VII, X, XI and XIII; combined vitamin-K dependent factors; α2-antiplasmin; and plasminogen activator inhibitor 1. Platelet disorders including Glanzmann's thrombasthenia and Bernard-Soulier syndrome are also addressed.
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Affiliation(s)
- Amy Shapiro
- Indiana Hemophilia & Thrombosis Center, 8326 Naab Rd., Indianapolis, IN 46260, USA.
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Rishavy MA, Hallgren KW, Zhang H, Runge KW, Berkner KL. Exon 2 skipping eliminates γ-glutamyl carboxylase activity, indicating a partial splicing defect in a patient with vitamin K clotting factor deficiency. J Thromb Haemost 2019; 17:1053-1063. [PMID: 31009158 PMCID: PMC7181818 DOI: 10.1111/jth.14456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 03/12/2019] [Indexed: 12/01/2022]
Abstract
Essentials A carboxylase mutation that impairs splicing to delete exon 2 sequences was previously reported. We found that the mutant was inactive for vitamin K-dependent (VKD) protein carboxylation. An incomplete splicing defect likely accounts for VKD clotting activity observed in the patient. The results indicate the importance of proper carboxylase embedment in the membrane for function. BACKGROUND Mutations in the γ-glutamyl carboxylase (GGCX), which is required for vitamin K-dependent (VKD) protein activation, can result in vitamin K clotting factor deficiency (VKCFD1). A recent report described a VKCFD1 patient with a homozygous carboxylase mutation that altered splicing and deleted exon 2 (Δ2GGCX). Only Δ2GGCX RNA was observed in the patient. OBJECTIVES Loss of exon 2 results in the deletion of carboxylase sequences thought to be important for membrane topology and consequent function. Carboxylase activity is required for life, and we therefore tested whether the Δ2GGCX mutant is active. METHODS HEK 293 cells were edited by the use of CRISPR-Cas9 to eliminate endogenous carboxylase. Recombinant wild-type GGCX and recombinant Δ2GGCX were then expressed and tested for carboxylation of the VKD protein factor IX. A second approach was used to monitor carboxylation biochemically, using recombinant carboxylases expressed in insect cells that lack endogenous carboxylase. RESULTS AND CONCLUSIONS Δ2GGCX activity was undetectable in both assays, which is strikingly different from the low levels of carboxylase activity observed with other VKCFD1 mutants. The similarity in clotting function between patients with Δ2GGCX and these mutations must therefore arise from a novel mechanism. Low levels of properly spliced carboxylase RNA that produce full-length protein would not have been observed in the previous study. The results suggest that the splicing defect is incomplete. Δ2GGCX RNA has been detected in normal human liver, and has been designated carboxylase isoform 2; however, Δ2GGCX protein was not observed in normal human liver. The lack of activity and protein expression suggest that isoform 2 is not physiologically relevant to normal VKD protein carboxylation.
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Affiliation(s)
- Mark A Rishavy
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine at CWRU, Cleveland Clinic, Cleveland, Ohio
| | - Kevin W Hallgren
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine at CWRU, Cleveland Clinic, Cleveland, Ohio
| | - Haitao Zhang
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine at CWRU, Cleveland Clinic, Cleveland, Ohio
| | - Kurt W Runge
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine at CWRU, Cleveland Clinic, Cleveland, Ohio
| | - Kathleen L Berkner
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine at CWRU, Cleveland Clinic, Cleveland, Ohio
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8
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GGCX-Associated Phenotypes: An Overview in Search of Genotype-Phenotype Correlations. Int J Mol Sci 2017; 18:ijms18020240. [PMID: 28125048 PMCID: PMC5343777 DOI: 10.3390/ijms18020240] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/21/2016] [Accepted: 01/13/2017] [Indexed: 11/16/2022] Open
Abstract
Gamma-carboxylation, performed by gamma-glutamyl carboxylase (GGCX), is an enzymatic process essential for activating vitamin K-dependent proteins (VKDP) with important functions in various biological processes. Mutations in the encoding GGCX gene are associated with multiple phenotypes, amongst which vitamin K-dependent coagulation factor deficiency (VKCFD1) is best known. Other patients have skin, eye, heart or bone manifestations. As genotype–phenotype correlations were never described, literature was systematically reviewed in search of patients with at least one GGCX mutation with a phenotypic description, resulting in a case series of 47 patients. Though this number was too low for statistically valid correlations—a frequent problem in orphan diseases—we demonstrate the crucial role of the horizontally transferred transmembrane domain in developing cardiac and bone manifestations. Moreover, natural history suggests ageing as the principal determinant to develop skin and eye symptoms. VKCFD1 symptoms seemed more severe in patients with both mutations in the same protein domain, though this could not be linked to a more perturbed coagulation factor function. Finally, distinct GGCX functional domains might be dedicated to carboxylation of very specific VKDP. In conclusion, this systematic review suggests that there indeed may be genotype–phenotype correlations for GGCX-related phenotypes, which can guide patient counseling and management.
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9
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Human teratogens and genetic phenocopies. Understanding pathogenesis through human genes mutation. Eur J Med Genet 2016; 60:22-31. [PMID: 27639441 DOI: 10.1016/j.ejmg.2016.09.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 09/12/2016] [Indexed: 12/27/2022]
Abstract
Exposure to teratogenic drugs during pregnancy is associated with a wide range of embryo-fetal anomalies and sometimes results in recurrent and recognizable patterns of malformations; however, the comprehension of the mechanisms underlying the pathogenesis of drug-induced birth defects is difficult, since teratogenesis is a multifactorial process which is always the result of a complex interaction between several environmental factors and the genetic background of both the mother and the fetus. Animal models have been extensively used to assess the teratogenic potential of pharmacological agents and to study their teratogenic mechanisms; however, a still open issue concerns how the information gained through animal models can be translated to humans. Instead, significant information can be obtained by the identification and analysis of human genetic syndromes characterized by clinical features overlapping with those observed in drug-induced embryopathies. Until now, genetic phenocopies have been reported for the embryopathies/fetopathies associated with prenatal exposure to warfarin, leflunomide, mycophenolate mofetil, fluconazole, thalidomide and ACE inhibitors. In most cases, genetic phenocopies are caused by mutations in genes encoding for the main targets of teratogens or for proteins belonging to the same molecular pathways. The aim of this paper is to review the proposed teratogenic mechanisms of these drugs, by the analysis of human monogenic disorders and their molecular pathogenesis.
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Watzka M, Geisen C, Scheer M, Wieland R, Wiegering V, Dörner T, Laws HJ, Gümrük F, Hanalioglu S, Unal S, Albayrak D, Oldenburg J. Bleeding and non-bleeding phenotypes in patients with GGCX gene mutations. Thromb Res 2014; 134:856-65. [PMID: 25151188 DOI: 10.1016/j.thromres.2014.07.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/13/2014] [Accepted: 07/07/2014] [Indexed: 11/30/2022]
Abstract
Functional limitations for the vitamin K cycle, caused either by mutations in gamma-glutamyl carboxylase or vitamin K epoxide reductase genes, result in hereditary deficiency of vitamin K-dependent coagulation factors (VKCFD1 and VKCFD2, respectively). Patients suffering from VKCFD often share several other anatomical irregularities which are not related to haemostasis. Here we report on nine patients, eight of them previously unreported, who presented with VKCFD1. All were examined with special attention to vitamin K-dependent coagulation factors as well as to bone and heart development and to other anatomical signs of embryonal vitamin K deficiency. In total, we detected ten mutations in the gamma-glutamyl carboxylase gene of which seven have not been previously reported. Most interestingly, additional non-bleeding phenotypes were observed in all patients including midfacial hypoplasia, premature osteoporosis, cochlear hearing loss, heart valve defects, pulmonary stenosis, or pseudoxanthoma elasticum-like phenotype. Undercarboxylated matrix Gla protein, osteocalcin, and periostin appear to be responsible for these defects which are also observed in cases of fetal warfarin syndrome.
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Affiliation(s)
- Matthias Watzka
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, 53105 Bonn, Germany
| | - Christof Geisen
- Institute of Transfusion Medicine and Immunohaematology, DRK Blood Donor Service Baden-Württemberg-Hessen, 60526 Frankfurt/Main, Germany
| | - Monika Scheer
- Pediatrics 5 (Oncology, Hematology, Immunology), Klinikum Stuttgart, Olgahospital, 70176 Stuttgart, Germany
| | - Regina Wieland
- Department of Paediatric Haematology and Oncology, Children's Hospital, University of Essen, 45122 Essen, Germany
| | - Verena Wiegering
- Department of Paediatric Haematology, Oncology, Paediatric Stem Cell Transplantation Program, University Children's Hospital Würzburg, 97080 Würzburg, Germany
| | - Thomas Dörner
- Department of Medicine/ Rheumatology and Clinical Immunology, Clinical Hemostaseology, Charité University Medicine Berlin, 10098 Berlin, Germany
| | - Hans-Jürgen Laws
- Department of Pediatric Oncology, Hematology and Clinical Immunology, Center of Child and Adolescent Health, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Fatma Gümrük
- Division of Pediatric Hematology, Faculty of Medicine, Hacettepe University, 06100 Sihhiye/Ankara, Turkey
| | - Sahin Hanalioglu
- Division of Pediatric Hematology, Faculty of Medicine, Hacettepe University, 06100 Sihhiye/Ankara, Turkey
| | - Sule Unal
- Division of Pediatric Hematology, Faculty of Medicine, Hacettepe University, 06100 Sihhiye/Ankara, Turkey
| | - Davut Albayrak
- Department of Pediatric Hematology, Ondokuz Mayis University, 55139 Samsun, Turkey
| | - Johannes Oldenburg
- Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, 53105 Bonn, Germany.
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Li WZ, Wang J, Long R, Su GH, Bukhory DK, Dai J, Jin N, Huang SY, Jia P, Li T, Fan C, Liu K, Wang Z. Novel antibody against a glutamic acid-rich human fibrinogen-like protein 2-derived peptide near Ser91 inhibits hfgl2 prothrombinase activity. PLoS One 2014; 9:e94551. [PMID: 24728278 PMCID: PMC3984148 DOI: 10.1371/journal.pone.0094551] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Accepted: 03/17/2014] [Indexed: 12/11/2022] Open
Abstract
Fibrinogen-like protein 2 (fgl2) is highly expressed in microvascular endothelial cells in diseases associated with microcirculatory disturbances and plays a crucial role in microthrombosis. Previous studies have demonstrated that the Ser89 residue is a critical site for mouse fgl2 prothrombinase activity. The aim of this study was to investigate the prothrombinase inhibitory ability of antibodies against an hfgl2-derived peptide. The peptide was termed NPG-12 because it is located at the N-terminus of membrane-bound hfgl2, contains 12 amino acid residues (corresponding to residues 76 to 87), and is rich in Glu. This peptide was selected as an antigenic determinant to produce antibodies in immunized rabbits using the DNAStar and HomoloGene software program. Abundant hfgl2 expression was induced in human umbilical vein endothelial cells through treatment with TNF-α. The generated anti-NPG-12 antibodies specifically recognize fgl2, as determined by ELISA, Western Blot and immunostaining. Moreover, one-stage clotting and thrombin generation tests provide evidence that the antibodies can reduce the hfgl2 prothrombinase activity without affecting the platelet-poor plasma prothrombin time (PT) or the activated partial thromboplastin time (APTT). In addition, the antibodies exerted undetectable influence on the proliferation or activation of bulk T cell populations. In conclusion, the selected peptide sequence NPG-12 may be a critical domain for hfgl2 prothrombinase activity, and the development of inhibitors against this sequence may be promising for research or management of hfgl2-associated microcirculatory disturbances.
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Affiliation(s)
- Wen-Zhu Li
- Department of Cardiology, Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jue Wang
- Department of Hematology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Rui Long
- Department of Geriatrics, Institute of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Guan-Hua Su
- Department of Cardiology, Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Dinesh-Kumar Bukhory
- Department of Cardiology, Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing Dai
- Department of Geriatrics, Institute of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Nan Jin
- Department of Geriatrics, Institute of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shi-Yuan Huang
- Department of Cardiology, Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Peng Jia
- Department of Cardiology, Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ting Li
- Department of Cardiology, Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chen Fan
- Department of Cardiology, Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kun Liu
- Department of Cardiology, Institute of Cardiovascular Disease, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhaohui Wang
- Department of Geriatrics, Institute of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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12
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Parker CH, Morgan C, Rand KD, Engen JR, Jorgenson J, Stafford DW. A conformational investigation of propeptide binding to the integral membrane protein γ-glutamyl carboxylase using nanodisc hydrogen exchange mass spectrometry. Biochemistry 2014; 53:1511-20. [PMID: 24512177 PMCID: PMC3970815 DOI: 10.1021/bi401536m] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 02/07/2014] [Indexed: 01/16/2023]
Abstract
Gamma (γ)-glutamyl carboxylase (GGCX) is an integral membrane protein responsible for the post-translational catalytic conversion of select glutamic acid (Glu) residues to γ-carboxy glutamic acid (Gla) in vitamin K-dependent (VKD) proteins. Understanding the mechanism of carboxylation and the role of GGCX in the vitamin K cycle is of biological interest in the development of therapeutics for blood coagulation disorders. Historically, biophysical investigations and structural characterizations of GGCX have been limited due to complexities involving the availability of an appropriate model membrane system. In previous work, a hydrogen exchange mass spectrometry (HX MS) platform was developed to study the structural configuration of GGCX in a near-native nanodisc phospholipid environment. Here we have applied the nanodisc-HX MS approach to characterize specific domains of GGCX that exhibit structural rearrangements upon binding the high-affinity consensus propeptide (pCon; AVFLSREQANQVLQRRRR). pCon binding was shown to be specific for monomeric GGCX-nanodiscs and promoted enhanced structural stability to the nanodisc-integrated complex while maintaining catalytic activity in the presence of carboxylation co-substrates. Noteworthy modifications in HX of GGCX were prominently observed in GGCX peptides 491-507 and 395-401 upon pCon association, consistent with regions previously identified as sites for propeptide and glutamate binding. Several additional protein regions exhibited minor gains in solvent protection upon propeptide incorporation, providing evidence for a structural reorientation of the GGCX complex in association with VKD carboxylation. The results herein demonstrate that nanodisc-HX MS can be utilized to study molecular interactions of membrane-bound enzymes in the absence of a complete three-dimensional structure and to map dynamic rearrangements induced upon ligand binding.
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Affiliation(s)
- Christine H. Parker
- Department of Chemistry and Department of
Biology, University of North Carolina at
Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Christopher
R. Morgan
- Department
of Chemistry & Chemical Biology, Northeastern
University, Boston, Massachusetts 02115, United States
| | - Kasper D. Rand
- Department
of Chemistry & Chemical Biology, Northeastern
University, Boston, Massachusetts 02115, United States
| | - John R. Engen
- Department
of Chemistry & Chemical Biology, Northeastern
University, Boston, Massachusetts 02115, United States
| | - James
W. Jorgenson
- Department of Chemistry and Department of
Biology, University of North Carolina at
Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Darrel W. Stafford
- Department of Chemistry and Department of
Biology, University of North Carolina at
Chapel Hill, Chapel Hill, North Carolina 27599, United States
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13
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Rishavy MA, Berkner KL. Vitamin K oxygenation, glutamate carboxylation, and processivity: defining the three critical facets of catalysis by the vitamin K-dependent carboxylase. Adv Nutr 2012; 3:135-48. [PMID: 22516721 PMCID: PMC3648714 DOI: 10.3945/an.111.001719] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The vitamin K-dependent carboxylase uses vitamin K oxygenation to drive carboxylation of multiple glutamates in vitamin K-dependent proteins, rendering them active in a variety of physiologies. Multiple carboxylations of proteins are required for their activity, and the carboxylase is processive, so that premature dissociation of proteins from the carboxylase does not occur. The carboxylase is unique, with no known homology to other enzyme families, and structural determinations have not been made, rendering an understanding of catalysis elusive. Although a model explaining the relationship of oxygenation to carboxylation had been developed, until recently almost nothing was known of the function of the carboxylase itself in catalysis. In the past decade, discovery and analysis of naturally occurring carboxylase mutants has led to identification of functionally relevant residues and domains. Further, identification of nonmammalian carboxylase orthologs has provided a basis for bioinformatic analysis to identify candidates for critical functional residues. Biochemical analysis of rationally chosen carboxylase mutants has led to breakthroughs in understanding vitamin K oxygenation, glutamate carboxylation, and maintenance of processivity by the carboxylase. Protein carboxylation has also been assessed in vivo, and the intracellular environment strongly affects carboxylase function. The carboxylase is an integral membrane protein, and topological analysis, coupled with biochemical determinations, suggests that interaction of the carboxylase with the membrane is an important facet of function. Carboxylase homologs, likely acquired by horizontal transfer, have been discovered in some bacteria, and functional analysis of these homologs has the potential to lead to the discovery of new roles of vitamin K in biology.
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14
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Rishavy MA, Hallgren KW, Berkner KL. The vitamin K-dependent carboxylase generates γ-carboxylated glutamates by using CO2 to facilitate glutamate deprotonation in a concerted mechanism that drives catalysis. J Biol Chem 2011; 286:44821-32. [PMID: 21896484 DOI: 10.1074/jbc.m111.249177] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The γ-glutamyl carboxylase converts Glu to carboxylated Glu (Gla) to activate a large number of vitamin K-dependent proteins with diverse functions, and this broad physiological impact makes it critical to understand the mechanism of carboxylation. Gla formation is thought to occur in two independent steps (i.e. Glu deprotonation to form a carbanion that then reacts with CO(2)), based on previous studies showing unresponsiveness of Glu deprotonation to CO(2). However, our recent studies on the kinetic properties of a variant enzyme (H160A) showing impaired Glu deprotonation prompted a reevaluation of this model. Glu deprotonation monitored by tritium release from the glutamyl γ-carbon was dependent upon CO(2), and a proportional increase in both tritium release and Gla formation occurred over a range of CO(2) concentrations. This discrepancy with the earlier studies using microsomes is probably due to the known accessibility of microsomal carboxylase to water, which reprotonates the carbanion. In contrast, tritium incorporation experiments with purified carboxylase showed very little carbanion reprotonation and consequently revealed the dependence of Glu deprotonation on CO(2). Cyanide stimulated Glu deprotonation and carbanion reprotonation to the same extent in wild type enzyme but not in the H160A variant. Glu deprotonation that depends upon CO(2) but that also occurs when water or cyanide are present strongly suggests a concerted mechanism facilitated by His-160 in which an electrophile accepts the negative charge on the developing carbanion. This revised mechanism provides important insight into how the carboxylase catalyzes the reaction by avoiding the formation of a high energy discrete carbanion.
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Affiliation(s)
- Mark A Rishavy
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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15
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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.
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Affiliation(s)
- Sangwook Wu
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, USA
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16
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17
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Wu S, Liu S, Davis CH, Stafford DW, Pedersen LG. Quantum Chemical Study of the Mechanism of Action of Vitamin K Carboxylase in Solvent. INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY 2010; 110:2744-2751. [PMID: 21892230 PMCID: PMC3164839 DOI: 10.1002/qua.22740] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We investigate the post-translational generation of Gla (γ-carboxy glutamic acid) from Glu (glutamic acid) by vitamin K carboxylase (VKC) in solvent. VKC is thought to convert vitamin K, in the vitamin K cycle, to an alkoxide-epoxide form, which then reacts with CO(2) to generate an essential ingredient in blood coagulation, γ-carboxyglutamic acid (Gla). The generation of Gla from Glu is found to be exergenic (-15 kcal/mol) in aqueous solution with the SM6 method. We also produced the free energy profile for this model biochemical process with other solvent methods (polarizable continuum model, dielectric polarizable continuum model) and different dielectric constants. The biological implications are discussed.
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Affiliation(s)
- Sangwook Wu
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290
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18
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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.
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Affiliation(s)
- Mark A Rishavy
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
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19
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Napolitano M, Mariani G, Lapecorella M. Hereditary combined deficiency of the vitamin K-dependent clotting factors. Orphanet J Rare Dis 2010; 5:21. [PMID: 20630065 PMCID: PMC2913942 DOI: 10.1186/1750-1172-5-21] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Accepted: 07/14/2010] [Indexed: 12/16/2022] Open
Abstract
Hereditary combined vitamin K-dependent clotting factors deficiency (VKCFD) is a rare congenital bleeding disorder resulting from variably decreased levels of coagulation factors II, VII, IX and X as well as natural anticoagulants protein C, protein S and protein Z. The spectrum of bleeding symptoms ranges from mild to severe with onset in the neonatal period in severe cases. The bleeding symptoms are often life-threatening, occur both spontaneously and in a surgical setting, and usually involve the skin and mucosae. A range of non-haemostatic symptoms are often present, including developmental and skeletal anomalies. VKCFD is an autosomal recessive disorder caused by mutations in the genes of either gamma-glutamyl carboxylase or vitamin K2,3-epoxide reductase complex. These two proteins are necessary for gamma-carboxylation, a post-synthetic modification that allows coagulation proteins to display their proper function. The developmental and skeletal anomalies seen in VKCFD are the result of defective gamma-carboxylation of a number of non-haemostatic proteins. Diagnostic differentiation from other conditions, both congenital and acquired, is mandatory and genotype analysis is needed to confirm the defect. Vitamin K administration is the mainstay of therapy in VKCFD, with plasma supplementation during surgery or severe bleeding episodes. In addition, prothrombin complex concentrates and combination therapy with recombinant activated FVII and vitamin K supplementation may constitute alternative treatment options. The overall prognosis is good and with the availability of several effective therapeutic options, VKCFD has only a small impact on the quality of life of affected patients.
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20
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Giansily-Blaizot M, Schved JF. Comprehensive pediatric care of rare bleeding disorders. ACTA ACUST UNITED AC 2010. [DOI: 10.2217/phe.10.15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Although less common than hemophilia or von Willebrand disease, inherited rare bleeding disorders, comprising afibrinogenemia and deficiencies in factors II, V, VII, X, XI, XIII or V plus VIII combined, or in vitamin K-dependent coagulation factors, may lead to severe bleeding episodes such as recurrent hemarthroses and neonatal intracranial or gastrointestinal hemorrhage. Consanguinity significantly increases the risk of the occurrence of all rare bleeding disorders that are associated with an autosomal recessive pattern of inheritance. Each of the disorders is characterized by a wide interindividual variation in clinical phenotype and a large mutational spectrum with no clear correlation between the phenotype and genotype. Replacement therapy relies on specific molecules or concentrates (afibrinogenemia, factor VII, XI and XIII deficiencies), on a mixture of different concentrates that are otherwise known as a prothrombin complex, which contains factors II, VII, IX and X, or on fresh frozen plasma. International consensus guidelines for treatment modalities are progressing; however, guidelines for prophylaxis, especially in pediatric patients, are lacking.
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Affiliation(s)
- Muriel Giansily-Blaizot
- Laboratoire d’hématologie, CHU de Montpellier, 80 avenue Augustin Fliche, 34095 Montpellier Cedex 5, France
| | - Jean-François Schved
- Laboratoire d’hématologie, CHU de Montpellier, 80 avenue Augustin Fliche, 34095 Montpellier Cedex 5, France
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21
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Abstract
Combined deficiency of vitamin K-dependent clotting factors II, VII, IX and X (and proteins C, S, and Z) is usually an acquired clinical problem, often resulting from liver disease, malabsorption, or warfarin overdose. A rare inherited form of defective gamma-carboxylation resulting in early onset of bleeding was first described by McMillan and Roberts in 1966 and subsequently has been termed 'vitamin K-dependent clotting factor deficiency' (VKCFD). Biochemical and molecular studies identify two variants of this autosomal recessive disorder: VKCFD1, which is associated with point mutations in the gamma-glutamylcarboxylase gene (GGCX), and VKCFD2, which results from point mutations in the vitamin K epoxide reductase gene (VKOR). Bleeding ranges in severity from mild to severe. Therapy includes high oral doses of vitamin K for prophylaxis, usually resulting in partial correction of factor deficiency, and episodic use of plasma infusions or prothrombin complex concentrate. Recent molecular studies have the potential to further our understanding of vitamin K metabolism, gamma-carboxylation, and the functional role this post-translational modification has for other proteins. The results may also provide potential targets for molecular therapeutics and pharmacogenetics.
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Affiliation(s)
- B W Weston
- The Harold R. Roberts Comprehensive Hemophilia Treatment Center, Department of Pediatrics, Division of Hematology-Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7220, USA.
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22
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Titapiwatanakun R, Rodriguez V, Middha S, Dukek BA, Pruthi RK. Novel splice site mutations in the gamma glutamyl carboxylase gene in a child with congenital combined deficiency of the vitamin K-dependent coagulation factors (VKCFD). Pediatr Blood Cancer 2009; 53:92-5. [PMID: 19340858 DOI: 10.1002/pbc.22011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Congenital combined deficiency of the vitamin K-dependent coagulation factors is a rare bleeding disorder caused by either a defect in the gamma-glutamyl carboxylase or the vitamin K epoxide reductase enzyme complex. The diagnosis should be considered when vitamin-K dependent factor activities are decreased and liver dysfunction, vitamin K deficiency, and factitious coumarin ingestion have been excluded. We report a case of VKCFD in a child resulting from compound heterozygosity for two novel splice site mutations of the gamma-glutamyl carboxylase gene. Oral vitamin K supplementation resulted in partial resolution of proteins and complete resolution of bleeding.
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23
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Abstract
Although used for many years, a detailed understanding of the mechanism of action and metabolism of anticoagulants has become available only recently. After the addition of pharmacogenetic data to the drug label by the U.S. Food and Drug Administration, interest in the pharmacogenetics of warfarin and its clinical application has grown exponentially. Dosing algorithms have been developed and continue to be refined that incorporate the polymorphisms of P450 2C9 and vitamin K epoxide reductase. Widespread adoption of these algorithms has been slow because of factors such as physician education, timely testing, complexity of dosing calculations, dietary variations, and other confounding variables. Although most useful before the first dose, these tests are also being used to explain labile responses to warfarin. Current protocols are capable of predicting a large portion of interindividual dosing variation and, as more data become available, truly personalized dosing of warfarin should be achievable, improving patient safety and clinical efficacy.
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Affiliation(s)
- Charles E Hill
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Emory University Hospital, 1364 Clifton Road, Atlanta, GA 30322, USA.
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24
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Li Q, Schurgers LJ, Smith ACM, Tsokos M, Uitto J, Cowen EW. Co-existent pseudoxanthoma elasticum and vitamin K-dependent coagulation factor deficiency: compound heterozygosity for mutations in the GGCX gene. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:534-40. [PMID: 19116367 PMCID: PMC2630561 DOI: 10.2353/ajpath.2009.080865] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/04/2008] [Indexed: 12/29/2022]
Abstract
Pseudoxanthoma elasticum (PXE) is a multisystem disorder characterized by ectopic mineralization of connective tissues with primary manifestations in the skin, eyes, and cardiovascular system. The classic forms of PXE are due to mutations in the ABCC6 gene that encodes the ABCC6 protein, a putative transmembrane transporter expressed primarily in the liver and the kidneys. PXE-like clinical findings have been encountered in association with vitamin K-dependent coagulation factor deficiency, an autosomal recessive disorder that is due to mutations in either the GGCX or VKORC1 genes. In this study, we investigated a family with two siblings with characteristic features of PXE and vitamin K-dependent coagulation factor deficiency. Mutation analysis identified two GGCX mutations in the affected individuals (p. R83W and p.Q374X); however, no mutations in either ABCC6 or VKORC1 could be found. GGCX encodes a gamma-glutamyl carboxylase necessary for activation of both coagulation factors in the liver and matrix gla protein, which, in fully carboxylated form, is able to prevent ectopic mineralization. Analysis of skin by specific antibodies demonstrated that matrix gla protein was found predominantly in undercarboxylated form and was associated with the mineralized areas in the patients' lesional skin. These observations pathomechanistically suggest that, in our patients, reduced carboxylase activity results in a reduction of matrix gla protein carboxylation, thus allowing peripheral mineralization to occur. Our findings also confirm GGCX as the second gene locus causing PXE.
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Affiliation(s)
- Qiaoli Li
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA
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25
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Franchini M, Mannucci PM. Multiple gene interaction and modulation of hemostatic balance. Clin Chem Lab Med 2009; 47:1455-60. [DOI: 10.1515/cclm.2009.331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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26
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Mutations in the GGCX and ABCC6 genes in a family with pseudoxanthoma elasticum-like phenotypes. J Invest Dermatol 2008; 129:553-63. [PMID: 18800149 DOI: 10.1038/jid.2008.271] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A characteristic feature of classic pseudoxanthoma elasticum (PXE), an autosomal recessive disorder caused by mutations in the ABCC6 gene, is aberrant mineralization of connective tissues, particularly the elastic fibers. Here, we report a family with PXE-like cutaneous features in association with multiple coagulation factor deficiency, an autosomal recessive disorder associated with GGCX mutations. The proband and her sister, both with severe skin findings with extensive mineralization, were compound heterozygotes for missense mutations in the GGCX gene, which were shown to result in reduced gamma-glutamyl carboxylase activity and in undercarboxylation of matrix gla protein. The proband's mother and aunt, also manifesting with PXE-like skin changes, were heterozygous carriers of a missense mutation (p.V255M) in GGCX and a null mutation (p.R1141X) in the ABCC6 gene, suggesting digenic nature of their skin findings. Thus, reduced gamma-glutamyl carboxylase activity in individuals either compound heterozygous for a missense mutation in GGCX or with haploinsufficiency in GGCX in combination with heterozygosity for ABCC6 gene expression results in aberrant mineralization of skin leading to PXE-like phenotype. These findings expand the molecular basis of PXE-like phenotypes, and suggest a role for multiple genetic factors in pathologic tissue mineralization in general.
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27
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Rishavy MA, Berkner KL. Insight into the coupling mechanism of the vitamin K-dependent carboxylase: mutation of histidine 160 disrupts glutamic acid carbanion formation and efficient coupling of vitamin K epoxidation to glutamic acid carboxylation. Biochemistry 2008; 47:9836-46. [PMID: 18717596 DOI: 10.1021/bi800296r] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vitamin K-dependent (VKD) proteins become activated by the VKD carboxylase, which converts Glu's to carboxylated Glu's (Gla's) in their Gla domains. The carboxylase uses vitamin K epoxidation to drive Glu carboxylation, and the two half-reactions are coupled in 1:1 stoichiometry by an unknown mechanism. We now report the first identification of a residue, His160, required for coupling. A H160A mutant showed wild-type levels of epoxidation but substantially less carboxylation. Monitoring proton abstraction using a peptide with Glu tritiated at the gamma-carbon position revealed that poor coupling was due to impaired carbanion formation. H160A showed a 10-fold lower ratio of tritium release to vitamin K epoxidation than wild-type enzyme (i.e., 0.12 versus 1.14, respectively), which could fully account for the fold decrease in coupling efficiency. The Ala substitution in His160 did not affect the K m for vitamin K and caused only a 2-fold increase in the K m for Glu and 2-fold decrease in the activation of vitamin K epoxidation by Glu. The H160A K m for CO 2 was 5-fold higher than the wild-type enzyme. However, the k cat for H160A carboxylation was 8-9-fold lower than the wild-type enzyme with all three substrates (i.e., Glu, CO 2, and vitamin K), suggesting a catalytic role for His160 in carbanion formation. We propose that His160 facilitates the formation of the transition state for carbanion formation. His160 is highly conserved in metazoan VKD carboxylases but not in some bacterial orthologues (acquired by horizontal gene transfer), which has implications for how bacteria have adapted the carboxylase for novel functions.
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Affiliation(s)
- Mark A Rishavy
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, 9500 Euclid Avenue, Cleveland, Ohio 44195, USA
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28
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Abstract
Vitamin K-dependent (VKD) protein carboxylation uses vitamin K epoxidation to convert Glus to carboxylated Glus (Glas), rendering VKD proteins active in physiologies that include hemostasis, apoptosis, bone mineralization, calcium homeostasis, growth control, and signal transduction. Clusters of Glus are modified by a processive carboxylase, generating a calcium-binding module that allows binding to either hydroxyapatite in the extracellular matrices or cell surfaces where anionic phospholipids become exposed, for example, during apoptosis or cell activation. Naturally occurring carboxylase mutations have been informative for function and are associated with bleeding complications and, surprisingly, a pseudoxanthoma elasticum (PXE)-like phenotype. A major advance in defining carboxylase function is the identification of the base that initiates carboxylation, which raises interesting possibilities for how vitamin K epoxidation is regulated by Glu substrate and carboxylase membrane topology. Vitamin K oxidoreductase (VKOR), the target of warfarin, generates the reduced vitamin K cofactor used by the carboxylase. Oxidation of active site thiols during vitamin K reduction inactivates VKOR, and activity is regenerated by an unknown reductase. The amounts of reduced vitamin K limit the capacity for carboxylation in cells, and overexpression of VKOR, but not carboxylase, improves carboxylation. However, the effect of VKOR overexpression is small, possibly because the reductase that regenerates VKOR activity is saturated. The review discusses these advances, as well as the potential impact of secretory components on carboxylation, which occurs during VKD protein secretion. Also discussed is the role of the carboxylase in mammals and lower organisms, including the bacterial pathogen Leptospira interrogans that has acquired a VKD carboxylase by horizontal transfer.
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Affiliation(s)
- Kathleen L Berkner
- Department of Molecular Cardiology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Lerner Research Institute, 9500 Euclid Avenue, Cleveland, Ohio 44195, USA
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29
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Zhu A, Sun H, Raymond RM, Furie BC, Furie B, Bronstein M, Kaufman RJ, Westrick R, Ginsburg D. Fatal hemorrhage in mice lacking gamma-glutamyl carboxylase. Blood 2007; 109:5270-5. [PMID: 17327402 PMCID: PMC1890832 DOI: 10.1182/blood-2006-12-064188] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The carboxylation of glutamic acid residues to gamma-carboxyglutamic acid (Gla) by the vitamin K-dependent gamma-glutamyl carboxylase (gamma-carboxylase) is an essential posttranslational modification required for the biological activity of a number of proteins, including proteins involved in blood coagulation and its regulation. Heterozygous mice carrying a null mutation at the gamma-carboxylase (Ggcx) gene exhibit normal development and survival with no evidence of hemorrhage and normal functional activity of the vitamin K-dependent clotting factors IX, X, and prothrombin. Analysis of a Ggcx(+/-) intercross revealed a partial developmental block with only 50% of expected Ggcx(-/-) offspring surviving to term, with the latter animals dying uniformly at birth of massive intra-abdominal hemorrhage. This phenotype closely resembles the partial midembryonic loss and postnatal hemorrhage previously reported for both prothrombin- and factor V (F5)-deficient mice. These data exclude the existence of a redundant carboxylase pathway and suggest that functionally critical substrates for gamma-carboxylation, at least in the developing embryo and neonate, are primarily restricted to components of the blood coagulation cascade.
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Affiliation(s)
- Aihua Zhu
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA
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