Vitamin K-dependent Proteins Research Articles

Vitamin K and the Visual System-A Narrative Review.

Vitamin K occupies a unique and often obscured place among its fellow fat-soluble vitamins. Evidence is mounting, however, that vitamin K (VK) may play an important role in the visual system apart from the hepatic carboxylation of hemostatic-related proteins. However, to our knowledge, no review covering the topic has appeared in the medical literature. Recent studies have confirmed that matrix Gla protein (MGP), a vitamin K-dependent protein (VKDP), is essential for the regulation of intraocular pressure in mice. The PREDIMED (Prevención con Dieta Mediterránea) study, a randomized trial involving 5860 adults at risk for cardiovascular disease, demonstrated a 29% reduction in the risk of cataract surgery in participants with the highest tertile of dietary vitamin K1 (PK) intake compared with those with the lowest tertile. However, the specific requirements of the eye and visual system (EVS) for VK, and what might constitute an optimized VK status, is currently unknown and largely unexplored. It is, therefore, the intention of this narrative review to provide an introduction concerning VK and the visual system, review ocular VK biology, and provide some historical context for recent discoveries. Potential opportunities and gaps in current research efforts will be touched upon in the hope of raising awareness and encouraging continued VK-related investigations in this important and highly specialized sensory system.

Targeted Blood Plasma Proteomics and Hemostasis Assessment of Post COVID-19 Patients with Acute Myocardial Infarction

The molecular mechanisms underlying cardiovascular complications after the SARS-CoV-2 infection remain unknown. The goal of our study was to analyze the features of blood coagulation, platelet aggregation, and plasma proteomics in COVID-19 convalescents with AMI. The study included 66 AMI patients and 58 healthy volunteers. The groups were divided according to the anti-N IgG levels (AMI post-COVID (n = 44), AMI control (n = 22), control post-COVID (n = 31), and control (n = 27)). All participants underwent rotational thromboelastometry, thrombodynamics, impedance aggregometry, and blood plasma proteomics analysis. Both AMI groups of patients demonstrated higher values of clot growth rates, thrombus size and density, as well as the elevated levels of components of the complement system, proteins modifying the state of endothelium, acute-phase and procoagulant proteins. In comparison with AMI control, AMI post-COVID patients demonstrated decreased levels of proteins connected to inflammation and hemostasis (lipopolysaccharide-binding protein, C4b-binding protein alpha-chain, plasma protease C1 inhibitor, fibrinogen beta-chain, vitamin K-dependent protein S), and altered correlations between inflammation and fibrinolysis. A new finding is that AMI post-COVID patients opposite the AMI control group, are characterized by a less noticeable growth of acute-phase proteins and hemostatic markers that could be explained by prolonged immune system alteration after COVID-19.

Proteomics analysis of serum from thymoma patients

Thymoma is the most common malignant tumor in thymic epithelial tumors (TETS). This study aimed to identify the changes in serum proteomics in patients with thymoma. Proteins were extracted from twenty patients with thymoma serum and nine healthy controls and prepared for mass spectrometry (MS) analysis. Data independent acquisition (DIA) quantitative proteomics technique was used to examine the serum proteome. Differential proteins of abundance changes in the serum were identified. Bioinformatics was used to examine the differential proteins. Functional tagging and enrichment analysis were conducted using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The string database was used to assess the interaction of different proteins. In all, 486 proteins were found in all samples. There were differences in 58 serum proteins between patients and healthy blood donors, 35 up-regulated and 23 down-regulated. These proteins are primarily exocrine and serum membrane proteins involved in controlling immunological responses and antigen binding, according to GO functional annotation. KEGG functional annotation showed that these proteins play a significant role in the complement and coagulation cascade and the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signal pathway. Notably, the KEGG pathway (complement and coagulation cascade) is enriched, and three key activators were up-regulated: von willebrand factor (VWF), coagulation factor v (F5) and vitamin k-dependent protein c (PC). Protein–protein interaction (PPI) analysis showed that six proteins ((VWF, F5, thrombin reactive protein 1 (THBS1), mannose-binding lectin-associated serine protease 2 (MASP2), apolipoprotein B (APOB), and apolipoprotein (a) (LPA)) were up-regulated and two proteins (Metalloproteinase inhibitor 1(TIMP1), ferritin light chain (FTL)) were down-regulated. The results of this study showed that several proteins involved in complement and coagulation cascades were up-regulated in the serum of patients.

Coagulation factor dysregulation in polycystic ovary syndrome is an epiphenomenon of obesity.

Obese women with polycystic ovary syndrome (PCOS) exhibit a hypercoagulable state, with the suggestion that this may be obesity-driven rather than an intrinsic facet of PCOS; however, this has not yet been definitively determined since body mass index (BMI)is so highly correlated with PCOS. Therefore, only a study design where obesity, insulin resistance and inflammation are matched can answer this question. This was a cohort study. Patients Weight and aged-matched nonobese women with PCOS (n = 29) and control women (n = 29) were included. Measurements Plasma coagulation pathway protein levels were measured. Circulating levels of a panel of nine clotting proteins known to differ in obese women with PCOS were determined by Slow Off-rate Modified Aptamer (SOMA)-scan plasma protein measurement. Women with PCOS showed a higher free androgen index (FAI) and anti-Müllerian hormone, but measures of insulin resistance, and C reactive protein (as a marker of inflammation), did not differ between the nonobese women with PCOS and the control women. Seven pro-coagulation proteins (plasminogen activator inhibitor-1, fibrinogen, fibrinogen gamma chain, fibronectin, d-dimer, P-selectinand plasma kallikrein) and two anticoagulant proteins (vitamin K-dependent protein-S and heparin cofactor-II) known to be elevated in obese women with PCOS did not differ from controls in this cohort. This novel data showthat clotting system abnormalities do not contribute to the intrinsic mechanisms underlying PCOS in this nonobese noninsulin resistant population of women with PCOS matched for age and BMI, and without evidence of underlying inflammation, but rather the clotting factor changes are an epiphenomenon coincident with obesity; therefore, increased coagulability is unlikely in these nonobese PCOS women.

Dysregulation of metalloproteins in ischemic heart disease patients with systolic dysfunction

Ischemic heart disease (IHD) is the leading cause of mortality worldwide. Metalloproteins have been linked to human health and diseases. The molecular functions of metalloproteins in IHD is not well understood and require further exploration. The objective of this study was to find out the role of metalloproteins in the pericardial fluid of IHD patients having normal (EF > 45) and impaired (EF < 45) left ventricular ejection fraction (LVEF). IHD patients were grouped into two categories: LVEF<45 (n = 12) and LVEF >45 (n = 33). Pooled samples of pericardial fluid were fractionated by using ZOOM-isoelectric focusing (IEF) followed by further processing using one-dimensional gel electrophoresis (1D SDS-PAGE) and filter-aided sample preparation (FASP). Tryptic peptides of each fraction and differential bands were then analyzed by nano-LC-ESI-MS/MS. Protein identification was performed through a Mascot search engine using NCBI-Prot and SwissProt databases. A total of 1082 proteins including 154 metalloproteins were identified. In the differential bands, 60 metalloproteins were identified, while 115 metalloproteins were identified in all ZOOM-IEF fractions. Twelve differentially expressed metalloproteins were selected in the intense bands according to their molecular weight (MW) and isoelectric point (pI). The 12 differentially expressed metalloprotein includes ceruloplasmin, Prothrombin, Vitamin K-dependent protein, Fibulin-1, Ribosomal protein S6 kinase alpha-6, nidogen, partial, Serum albumin, Hemopexin, C-reactive protein, Serum amyloid P-component, and Intelectin-1 protein which were all up-regulated while serotransferrin is the only metalloprotein that was down-regulated in impaired (LVEF<45) group. Among the metalloproteins, Zn-binding proteins are 36.5 % followed by Ca-binging 32.2 %, and Fe-binging 12.2 %. KEGG, pathway analysis revealed the association of ceruloplasmin and serotransferrin with the ferroptosis pathway. In conclusion, 154 metalloproteins were identified of them the Zn-binding protein followed by Ca-binding and Fe-binding proteins were the most abundant metalloproteins. The two metalloproteins, the Cu-binding protein ceruloplasmin, and Fe-binding protein serotransferrin are involved in the ferroptosis pathway, an iron-dependent form of regulated cell death that has been linked to cardiac pathology, especially in IHD patients having impaired systolic (LVEF<45) dysfunction. However, further research is required to validate these findings.

Plasma GAS6 predicts mortality risk in acute heart failure patients: insights from the DRAGON-HF trial

BackgroundGrowth arrest-specific 6 (GAS6) is a vitamin K-dependent protein related to inflammation, fibrosis, as well as platelet function. Genetic ablation of GAS6 in mice protects against cardiac hypertrophy and dysfunction. Nonetheless, the association between plasma GAS6 levels and acute heart failure (AHF) patients is still unknown.MethodsWe measured plasma GAS6 concentrations in 1039 patients with AHF who were enrolled in the DRAGON-HF trial (NCT03727828). Mean follow-up of the study was 889 days. The primary endpoint is all-cause death.ResultsIn total, there were 195 primary endpoints of all-cause death and 135 secondary endpoints of cardiovascular death during the mean follow-up duration of 889 days. The higher levels of GAS6 were associated with higher rates of all-cause and cardiovascular death (P < 0.05). Baseline plasma GAS6 levels were still strongly correlated with clinical outcomes in different models after adjustment for clinical factors and N-terminal pro-brain natriuretic peptide (NT-proBNP, P < 0.05). GAS6 could further distinguish the risks of clinical outcomes based on NT-proBNP measurement.ConclusionElevated plasma GAS6 levels were associated with an increased risk of all-cause and cardiovascular death in patients with AHF.Trial registration NCT03727828 (DRAGON-HF trial) clinicaltrials.gov

Gas6/TAM Axis Involvement in Modulating Inflammation and Fibrosis in COVID-19 Patients.

Gas6 (growth arrest-specific gene 6) is a widely expressed vitamin K-dependent protein that is involved in many biological processes such as homeostatic regulation, inflammation and repair/fibrotic processes. It is known that it is the main ligand of TAMs, a tyrosine kinase receptor family of three members, namely MerTK, Tyro-3 and Axl, for which it displays the highest affinity. Gas6/TAM axis activation is known to be involved in modulating inflammatory responses as well as fibrotic evolution in many different pathological conditions. Due to the rapidly evolving COVID-19 pandemic, this review will focus on Gas6/TAM axis activation in SARS-CoV-2 infection, where de-regulated inflammatory responses and fibrosis represent a relevant feature of severe disease manifestation. Furthermore, this review will highlight the most recent scientific evidence supporting an unsuspected role of Axl as a SARS-CoV-2 infection driver, and the potential therapeutic advantages of the use of existing Axl inhibitors in COVID-19 management. From a physiological point of view, the Gas6/TAM axis plays a dual role, fostering the tissue repair processes or leading to organ damage and loss of function, depending on the prevalence of its anti-inflammatory or profibrotic properties. This review makes a strong case for further research focusing on the Gas6/TAM axis as a pharmacological target to manage different disease conditions, such as chronic fibrosis or COVID-19.

Novel Gamma-Glutamyl Carboxylase Mutation Causing Hemorrhagic and Non-Hemorrhagic VKCFD1 Phenotypes

Background: Vitamin K clotting factor deficiency (VKCFD) types 1 and 2 are very rare autosomal recessive disorders associated with reduced clotting factors activities for all vitamin K dependent clotting factors. Less than 30 cases are reported with defects in GGCX (gamma-glutamyl carboxylase) leading to VKCFD Type 1 (VKCFD1) or VKORC1 (vitamin K epoxide reductase complex subunit 1) leading to VKCFD Type 2 (VKCFD2). In addition to clotting factor deficiency, GGCX mutations can be associated with skeletal abnormalities such as bone hypoplasia, conductive hearing loss, mental retardation, and skin hyperlaxity. Here, we report an Arabic family with VKCFD1 harboring an unreported, new pathogenic variant in the GGCX gene. The proband presented at 17 months of age with severe bruising following trauma and work up demonstrated deficiencies of all Vitamin K dependent (VKD) coagulation proteins. Another sibling born 8 years later was also diagnosed with the same condition with abnormal coagulation parameters at birth. Additionally, the non-hemorrhagic manifestations diagnosed in both siblings were mid-facial hypoplasia with flat nasal bridge, dental abnormalities, and shortened distal phalanges representing a keutel syndrome-like phenotype. Both patients are currently managed with oral vitamin K supplementation with resolution of bleeding symptoms. Here we present the in-vitro assessment of the mutations effects to vitamin K supplementation and potential clinical implications. Methods: The proband, affected brother and mother, all underwent genetic evaluation at the University Clinic Bonn in Germany. DNA was isolated from the patient's blood and Sanger Sequencing was performed for the genes VKORC1 and GGCX. The identified new pathogenic variant in GGCX was further characterized by the in-vitro assay published by Ghosh et al. in 2021. Results: The brothers were found to be homozygous for c.[416G>A];[416G>A] p.(Cys139Tyr), a genetic variant in exon 4 of the GGCX gene. Mutations in VKORC1 gene leading to reduced activity for the VKD clotting factors were excluded confirming the diagnosis of VKCFD Type 1 (VKCFD1). The mother was found to be heterozygous for the same GGCX variant. The affected siblings and the mother were further genotyped for the promoter single nucleotide polymorphism in VKORC1 gene NG_011564.1:g.3588G>A (VKORC1:c.-1639 G>A) since this might correlate with the severity of the phenotypes in patients with skeletal manifestations. The brothers and mother were found to harbor VKORC1:c.-1639 GA, which has been associated with a 33% reduced VKORC1 expression. Treatment with 5mg of vitamin K resulted in increased activities of the VKD clotting factors (Table 1). However, clotting factor activities did not normalized after vitamin K supplementation. The in vitro characterization of the new identified pathogenic variant GGCX:p.C139Y (Figure 1) showed reduced activities for all VKD clotting factors, which did not reach wild type levels despite increasing concentrations of vitamin K. The levels of Matrix Gla protein (MGP), Bone Gla protein (BGLAP), and Gla-rich protein (GRP) showed almost no response to increasing amount of vitamin K. Discussion: Here, we report a new pathogenic variant in exon 4 of GGCX c.[416G>A];[416G>A] p.(Cys139Tyr) leading to VKCFD1 with reduced clotting factor activities and non-hemorrhagic manifestations. The pre and post vitamin K supplementation factor levels in the patients correlate with the in-vitro data and demonstrate failure of the clotting factor levels to normalize despite vitamin K supplementation. The in vitro data for the non-hematological VKD proteins indicate that the patients might develop a pseudoxanthoma elasticum (PXE)-like phenotype resulting into hyperlaxity of skin due to the almost zero levels of carboxylated GRP. The skeletal/bone phenotypes can be explained by the almost zero values for carboxylated MGP and GRP. To assess this in-vivo, levels of human MGP and BGLAP are currently being analyzed in the patients and mothers blood samples. These patients highlight the nuances associated with the diagnosis and management of patients with VKCFD. The antenatal management and timing of Vitamin K supplementation to prevent intrauterine bleeding is also unknown, and there may be benefit to starting early to prevent the bone and skin manifestations. Further research is warranted in rare bleeding disorders such as VKCFD. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Protein S Deficiency with Recurrent Deep Vein Thrombosis and Post Thrombotic Syndrome: A Case Report

deep vein thrombosis; protein S deficiency; rivaroxaban.

New insights into vitamin K biology with relevance to cancer.

Phylloquinone (vitamin K1) and menaquinones (vitamin K2 family) are essential for post-translational γ-carboxylation of a small number of proteins, including clotting factors. These modified proteins have now been implicated in diverse physiological and pathological processes including cancer. Vitamin K intake has been inversely associated with cancer incidence and mortality in observational studies. Newly discovered functions of vitamin K in cancer cells include activation of the steroid and xenobiotic receptor (SXR) and regulation of oxidative stress, apoptosis, and autophagy. We provide an update of vitamin K biology, non-canonical mechanisms of vitamin K actions, the potential functions of vitamin K-dependent proteins in cancer, and observational trials on vitamin K intake and cancer.

Blood plasma proteome alteration after local tissue damage induced by Bothrops erythromelas snake venom in mice

Snakes of the genus Bothrops are responsible the most snakebites in the Brazil, causing a diverse and complex pathophysiological condition. Bothrops erythromelas is the main specie of medical relevance found in the Caatinga from the Brazilian Northeast region. The pathophysiological effects involving B. erythromelas snakebite as well as the organism reaction in response to this envenomation are not so explored. Thus, edema was induced in mice paws using 2.5 μg or 5.0 μg of B. erythromelas venom, and the percentage of edema was measured. Plasma was collected 30 minutes after the envenomation-induced in mice and analyzed by mass spectrometry. It was identified a total of 112 common plasma proteins differentially abundant among experimental groups, which are involved with the complement system and coagulation cascades, oxidative stress, neutrophil degranulation, platelets degranulation and inflammatory response. Apolipoprotein A1 (Apoa), serum amyloid protein A-4 (Saa4), adiponectin (Adipoq) showed up-regulated in mice plasma after injection of venom, while fibulin (Fbln1), factor XII (F12) and vitamin K-dependent protein Z (Proz) showed down-regulated. The results indicate a protein pattern of thrombo-inflammation to the B. erythromelas snakebite, evidencing potential biomarkers for monitoring this snakebite, new therapeutic targets and its correlations with the degree of envenomation once showed modulations in the abundance among the different groups according to the amount of venom injected into the mice.

Vitamin K as a Simple but Efficient Add-on to the Current Treatment Regime of COVID-19: A Narrative Review

Background: Intravascular thrombosis and pulmonary fibrosis in COVID-19 patients with pneumonia are significantly associated with the severity of the disease. Vitamin K is known to balance the coagulation mechanisms and also prevent calcification and fibrosis of the extrahepatic soft tissues. This narrative review focuses on the role of vitamin K as a linking factor for thrombotic as well as pulmonary complications of COVID-19. Methods and Results: Article search was performed in databases of WHO, PubMed, Scopus and Clinical Trial Registry using appropriate keywords. Original articles included very few observational studies which showed a reduced level of vitamin K as well as activated extrahepatic vitamin K Dependent Proteins (VKDP) in COVID-19 patients when compared to healthy controls. Chronic treatment with vitamin K Antagonists did not reduce the risk of in-hospital death. Docking study was performed using Swiss dock, and it demonstrated a significant interaction between menaquinone and SARS-CoV-2 main protease (SARS-CoV-2 Mpro). Discussion: Deficiency of vitamin K in COVID-19 can be due to excessive use of antagonists or defective ingestion or absorption. This triggers an imbalance in the normal coagulation- anticoagulation mechanism by channeling the available vitamin K to the liver, thereby causing a deficiency of the same in extrahepatic tissues, thus finally leading to thrombosis. This also prevents carboxylation and activation of extrahepatic VKDP required to prevent the calcification of soft tissues, thus leading to lung fibrosis. Conclutions: Supplementation of vitamin K should be considered as a potentially modifiable risk factor in severe COVID-19. Randomized control trials are highly recommended to provide clearer evidence on the same.

Role of vitamin K2 in bone-vascular crosstalk.

Vitamin K (VK) is a fat-soluble vitamin that is indispensable for the activation of vitamin K-dependent proteins (VKDPs). It has been shown to play an important role in the proper calcium deposit at the bone level, hindering that on the vascular walls. The deficiency of this vitamin in European populations is frequent and unknown. It is related to several factors, poor dietary intake, altered intestinal absorption or altered production by bacteria, indicating possible dysbiosis. For Vitamin K2 (VK2), there is currently no official reference daily intake (RDI). However, the effects of VK2 on the improvement of health in cardiovascular diseases, on bone metabolism, on chronic kidney diseases have been the subject of research in recent decades. The microbiota in the gastrointestinal tract plays an important role: Bacteroides are primarily capable of synthetizing very long chain forms of menaquinones and, in addition to the bacteria present in the intestinal flora, VK2 is also produced by bacteria used in food fermentation processes. This review provides an update on the current literature regarding the origin of VK2 and its implications in what is called the "calcium paradox", namely the lack of calcium in the bone and its storage in the wall of the vessel.

Vitamin K1 and progression of cardiovascular calcifications in hemodialysis patients: the VitaVasK randomized controlled trial.

Cardiovascular calcifications are prevented by matrix Gla protein (MGP), a vitamin K-dependent protein. Haemodialysis patients exhibit marked vitamin K deficiency. The randomized, prospective, open-label, multicentre VitaVasK trial analysed whether vitamin K1 supplementation reduces progression of coronary artery calcifications (CACs) and thoracic aortic calcifications (TACs). Patients with pre-existing CACs were randomized to continue on standard care or to additionally receive 5mg of vitamin K1 orally thrice weekly. Hierarchically ordered primary endpoints were progression of TAC and CAC in computed tomography scans at 18months. Linear mixed effects models with repeated measures at baseline and 12 and 18months assessed treatment effects after adjusting for study site. Of 60 randomized patients, 20 dropped out for reasons unrelated to vitamin K1, resulting in 23 control and 17 vitamin K1 patients. The trial was stopped early due to slow recruitment. At 18months, the average TAC progression was 56% lower in the vitamin K1 compared with the control group (p=.039). CAC significantly progressed within the control group, but not within the vitamin K1 group. Average progression at 18 months was 68% lower in the vitamin K1 compared to the control group (P=.072). Vitamin K1 reduced plasma levels of pro-calcific uncarboxylated MGP by 69% at 18months. No treatment-related adverse events were noted. Vitamin K1 intervention is a potent, safe and cost-effective approach to correct vitamin K deficiency and to potentially reduce cardiovascular calcification in this high-risk population.

Vitamin K : A Micro-Nutrient with New Perspective

Age-related diseases are becoming more common as people live longer. According to scientific research, a nutritious diet containing beneficial fats, vitamins, minerals, or polyphenols may have antioxidant and antioxidant properties that slow ageing. Studies also show that vitamin K is an essential cofactor in activating many proteins that fight age-related diseases. Vitamin k1 (phylloquinone), which is mainly contained in plants, and vitamin k2 (menaquinone), which is mainly contained in animal foods and dairy products, are both naturally occurring fat-soluble vitamins. Benefits of vitamin K include improved heart disease, bone and cognitive health, and blood clotting. Vitamin K-dependent proteins such as clotting factors (II, VII, IX, X and prothrombin), protein C and protein S, osteocalcin, matrix Gla protein, and periostin support calcium homeostasis and regulate vascular wall mineralization. Inhibits and promotes bone mineralization. Controls and a host of other sequelae. Currently, the demand for vitamin K in health products is increasing. It is found mainly in dairy and meat products, vegetable oils, and green leafy vegetables. Adults need approximately 1 µg of vitamin K per kg of body weight. Vitamin K is popular because it deposits less, needs replenishment, and is difficult to absorb. This review seeks to synthesize information on the origin, metabolism of many forms of vitamin K, deficiency, recommended dietary intake, toxicity, and the role of vitamin K in preventing various therapeutic disorders.

Urinary matrix Gla protein is associated with mortality risk in Flemish population: A prospective study.

BackgroundVascular calcification is strongly related to the risk of mortality and cardiovascular (CV) diseases. In vascular calcification, matrix Gla protein (MGP), a small vitamin K-dependent protein, is an important mineralization inhibitor. Recent studies showed that circulating MGP is associated with mortality risk. However, the longitudinal association between urinary excretion of MGP and all-cause mortality was not established.Materials and methodsUrinary MGP was measured in 776 randomly recruited Flemish population (mean age: 51.2 years; 50.9% women) at baseline (during 2005–2010) using capillary electrophoresis coupled with mass spectrometry. Plasma inactive MGP [desphospho-uncarboxylated MGP (dp-ucMGP)] levels were quantified in 646 individuals by ELISA kits. Mortality status was ascertained through the Belgian Population Registry until 2016. The longitudinal association with mortality was determined by the multivariate-adjusted Cox proportional hazards regression models. The multivariate linear regression models were used to identify determinants of urinary MGP level.ResultsOver the 9.2 years, 47 (6.06%) participants died, including 15 CV deaths. For a doubling of urinary MGP, the hazard ratios (HRs) were 1.31 (95% CI: 1.01–1.69, P = 0.040) for all-cause mortality and 2.05 (95% CI: 1.11–3.79, P = 0.023) for CV mortality with adjustment for covariates, including estimated glomerular filtration rate and urine microalbumin. The addition of urinary MGP to the basic models improved the reclassification as suggested by the increased net reclassification improvement [64.01% (95% CI: 32.64–98.63)] and integrated discrimination improvement [2.33% (95% CI: 0.24–4.71)]. Circulating inactive MGP, total cholesterol, urine microalbumin, and smoking were significantly associated with urinary MGP levels (P ≤ 0.041), independent of sex and age.ConclusionElevated urinary MGP was associated with an increased risk of all-cause mortality and CV mortality and improved the risk reclassification for all-cause mortality. These findings suggested that urinary MGP might be useful in mortality risk assessment in the general population. However, these observations need to be replicated in larger studies with a longer follow-up time.

Molecular View into Preferential Binding of the Factor VII Gla Domain to Phosphatidic Acid.

Factor VII (FVII) is a serine protease with a key role in initiating the coagulation cascade. It is part of a family of vitamin K-dependent clotting proteins, which require vitamin K for formation of their specialized membrane-binding domains (Gla domains). Membrane binding of the FVII Gla domain is critical to the activity of FVII, mediating the formation of its complex with other clotting factors. While Gla domains among coagulation factors are highly conserved in terms of amino acid sequence and structure, they demonstrate differential binding specificity toward anionic lipids. Although most Gla domain-containing clotting proteins display a strong preference for phosphatidylserine (PS), it has been demonstrated that FVII and protein C instead bind preferentially to phosphatidic acid (PA). We have developed the first model of the FVII Gla domain bound to PA lipids in membranes containing PA, the highly mobile membrane mimetic model, which accelerates slow diffusion of lipids in molecular dynamics simulations and therefore facilitates the membrane binding process and enhances sampling of lipid interactions. Simulations were performed using atomic level molecular dynamics, requiring a fixed charge to all atoms. The overall charge assigned to each PA lipid for this study was -1. We also developed an additional model of the FVII Gla domain bound to a 1:1 PS/PC membrane and compared the modes of binding of PS and PA lipids to FVII, allowing us to identify potential PA-specific binding sites.

GGCX mutants that impair hemostasis reveal the importance of processivity and full carboxylation to VKD protein function

Abstractγ-Glutamyl carboxylase (GGCX) generates multiple carboxylated Glus (Glas) in vitamin K–dependent (VKD) proteins that are required for their functions. GGCX is processive, remaining bound to VKD proteins throughout multiple Glu carboxylations, and this study reveals the essentiality of processivity to VKD protein function. GGCX mutants (V255M and S300F) whose combined heterozygosity in a patient causes defective clotting and calcification were studied using a novel assay that mimics in vivo carboxylation. Complexes between variant carboxylases and VKD proteins important to hemostasis (factor IX [FIX]) or calcification (matrix Gla protein [MGP]) were reacted in the presence of a challenge VKD protein that could potentially interfere with carboxylation of the VKD protein in the complex. The VKD protein in the complex with wild-type carboxylase was carboxylated before challenge protein carboxylation occurred and became fully carboxylated. In contrast, the V255M mutant carboxylated both forms at the same time and did not completely carboxylate FIX in the complex. S300F carboxylation was poor with both FIX and MGP. Additional studies analyzed FIX- and MGP-derived peptides containing the Gla domain linked to sequences that mediate carboxylase binding. The total amount of carboxylated peptide generated by the V255M mutant was higher than that of wild-type GGCX; however, the individual peptides were partially carboxylated. Analysis of the V255M mutant in FIX HEK293 cells lacking endogenous GGCX revealed poor FIX clotting activity. This study shows that disrupted processivity causes disease and explains the defect in the patient. Kinetic analyses also suggest that disrupted processivity may occur in wild-type carboxylase under some conditions (eg, warfarin therapy or vitamin K deficiency).

Arterial stiffness, vascular calcification and osteoporosis — common mechanisms of interaction (literature review)

Introduction. The problem of cardiovascular morbidity and mortality remains an urgent issue of modern medicine, and arterial stiffness is its independent predictor. Lively discussions about the correct approach to the prevention and treatment of comorbid conditions – increased vascular stiffness as an influential factor of the cardiovascular events and decreased bone mineral density (osteoporosis), primarily arise against the background of the need and safety of calcium and vitamin D supplements. The purpose was to search for literature data as for possible common pathogenetic links in the progression of arterial stiffness and the development of osteoporosis in order to assess the safety of the use of drugs to prevent osteoporotic fractures. Results. Analysis of literature sourses had showed that possible osteogenic factors affecting arterial stiffness may be: secondary hyperparathyroidism, disbalance of the RANK/RANKL/OPG system, inhibition of vitamin K-dependent matrix proteins (Gla-protein), osteopontin, etc. Conclusions. Today, there are many hypotheses confirming the possible influence of osteogenic factors on vascular stiffness and arterial calcification. Therefore, the search for sensitive markers and the development of screening protocols for the patients with risk factors for both osteoporosis and vascular changes are extremely relevant. A special issue is the possibility of using monotherapy for these comorbid pathologies, which can safely and efficiently influence the prevention of complications – both low-energy osteoporotic fractures and cardiovascular catastrophes. This will be the focus of our further research.

Association of desphospho-uncarboxylated matrix gla protein with incident cardiovascular disease and all-cause mortality: Results from the prospective Bruneck Study

Background and aimsMatrix Gla protein (MGP), a vitamin K-dependent protein, is a potent inhibitor of vascular calcification. Desphospho-uncarboxylated MGP (dp-ucMGP), a marker of vitamin K insufficiency, has been shown to predict cardiovascular disease (CVD) and all-cause mortality in high-risk populations. Whether the increased risk associated with dp-ucMGP also applies to the general, and especially, the elderly population has not yet been fully elucidated. Methods and resultsPlasma dp-ucMGP was measured in 684 individuals aged 50–89 years of the prospective population-based Bruneck Study (baseline evaluation in 2000). Baseline median dp-ucMGP was 478.4 (IQR 335.0–635.2) pmol/L. Over a median follow-up of 15.5 years, 163 CVD events occurred and 235 participants died. Age-/sex-adjusted hazard ratios (HRs) per 1-SD higher level of loge transformed dp-ucMGP were 1.30 (95%CI: 1.09–1.55; p=0.004) for incident CVD and 1.36 (95%CI: 1.17–1.57; p<0.001) for all-cause mortality. After multivariable adjustment, the associations remained significant with HRs of 1.23 (95%CI: 1.02–1.47, p=0.029) for CVD and 1.40 (95%CI: 1.20–1.64; p<0.001) for all-cause mortality. The associations remained virtually unchanged after additional adjustment for dietary quality as measured with the Alternative Healthy Eating Index. We found no association of dp-ucMGP with myocardial infarction and sudden cardiac deaths, but a strong association with other vascular deaths and non-vascular/non-cancer deaths. ConclusionsThis study shows a significant association of plasma dp-ucMGP with incident CVD and a significant and even stronger association with all-cause mortality. Clinical trials are needed to investigate whether vitamin K substitution results in improved health outcomes.