scholarly journals Vitamin K-dependent proteins: osteocalcin, matrix Gla-protein and extra osseous effects

2013 ◽  
Vol 10 (2) ◽  
pp. 11-18
Author(s):  
Yu В Pankratova ◽  
E A Pigarova ◽  
L K Dzeranova

Vitamin K - is a fat-soluble vitamin which plays an important role in the metabolism of bone and connective tissue, maintenance blood clotting properties. Vitamin K is involved in carboxylation of glutamic acid residues in the polypeptide chains of 14 human proteins, providing them with the necessary functional properties. Lack of vitamin K-dependent carboxylation of these proteins leads to changes in their biological activity. In this literature review we cover the mechanisms of vitamin K-dependent carboxylation and none bone actions of osteocalcin and matrix Gla-protein with different degrees of carboxylation.

1968 ◽  
Vol 20 (01/02) ◽  
pp. 078-087 ◽  
Author(s):  
H. C Hemker ◽  
A. D Muller

SummaryPIVKA, the circulating anticoagulant protein found in vitamin K deficiency can, on kinetical grounds, be recognized as an analogue of factor X. The existence of analogues of other vitamin K-dependent clotting factors cannot be ruled out, but need not be assumed to explain the experimental results.


2018 ◽  
Vol 22 (1) ◽  
pp. 29-37
Author(s):  
N. Y. Petkova ◽  
K. B. Petrova ◽  
M. I. Bliznakova ◽  
D. N. Paskalev ◽  
B. T. Galunska

2021 ◽  
Vol 80 (5) ◽  
pp. 598-604
Author(s):  
Cindy G Boer ◽  
Ingrid Szilagyi ◽  
N Long Nguyen ◽  
Tuhina Neogi ◽  
Ingrid Meulenbelt ◽  
...  

ObjectivesVitamin K is hypothesised to play a role in osteoarthritis (OA) pathogenesis through effects on vitamin K-dependent bone and cartilage proteins, and therefore may represent a modifiable risk factor. A genetic variant in a vitamin K-dependent protein that is an essential inhibitor for cartilage calcification, matrix Gla protein (MGP), was associated with an increased risk for OA. Vitamin K antagonist anticoagulants (VKAs), such as warfarin and acenocoumarol, act as anticoagulants through inhibition of vitamin K-dependent blood coagulation proteins. VKAs likely also affect the functioning of other vitamin K-dependent proteins such as MGP.MethodsWe investigated the effect of acenocoumarol usage on progression and incidence of radiographic OA in 3494 participants of the Rotterdam Study cohort. We also examined the effect of MGP and VKORC1 single nucleotide variants on this association.ResultsAcenocoumarol usage was associated with an increased risk of OA incidence and progression (OR=2.50, 95% CI=1.94–3.20), both for knee (OR=2.34, 95% CI=1.67–3.22) and hip OA (OR=2.74, 95% CI=1.82–4.11). Among acenocoumarol users, carriers of the high VKORC1(BB) expression haplotype together with the MGP OA risk allele (rs1800801-T) had an increased risk of OA incidence and progression (OR=4.18, 95% CI=2.69–6.50), while this relationship was not present in non-users of that group (OR=1.01, 95% CI=0.78–1.33).ConclusionsThese findings support the importance of vitamin K and vitamin K-dependent proteins, as MGP, in the pathogenesis of OA. Additionally, these results may have direct implications for the clinical prevention of OA, supporting the consideration of direct oral anticoagulants in favour of VKAs.


2020 ◽  
Vol 22 (1) ◽  
pp. 278
Author(s):  
Jianjian Sun ◽  
Peilu She ◽  
Xu Liu ◽  
Bangjun Gao ◽  
Daqin Jin ◽  
...  

Pseudoxanthoma elasticum (PXE), caused by ABCC6/MRP6 mutation, is a heritable multisystem disorder in humans. The progressive clinical manifestations of PXE are accompanied by ectopic mineralization in various connective tissues. However, the pathomechanisms underlying the PXE multisystem disorder remains obscure, and effective treatment is currently available. In this study, we generated zebrafish abcc6a mutants using the transcription activator-like effector nuclease (TALEN) technique. In young adult zebrafish, abcc6a is expressed in the eyes, heart, intestine, and other tissues. abcc6a mutants exhibit extensive calcification in the ocular sclera and Bruch’s membrane, recapitulating part of the PXE manifestations. Mutations in abcc6a upregulate extracellular matrix (ECM) genes, leading to fibrotic heart with reduced cardiomyocyte number. We found that abcc6a mutation reduced levels of both vitamin K and pyrophosphate (PPi) in the serum and diverse tissues. Vitamin K administration increased the gamma-glutamyl carboxylated form of matrix gla protein (cMGP), alleviating ectopic calcification and fibrosis in vertebrae, eyes, and hearts. Our findings contribute to a comprehensive understanding of PXE pathophysiology from zebrafish models.


Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 737
Author(s):  
Marko Kumric ◽  
Josip A. Borovac ◽  
Tina Ticinovic Kurir ◽  
Dinko Martinovic ◽  
Ivan Frka Separovic ◽  
...  

Coronary artery disease (CAD) is widely recognized as one of the most important clinical entities. In recent years, a large body of accumulated data suggest that coronary artery calcification, a process highly prevalent in patients with CAD, occurs via well-organized biologic processes, rather than passively, as previously regarded. Matrix Gla protein (MGP), a vitamin K-dependent protein, emerged as an important inhibitor of both intimal and medial vascular calcification. The functionality of MGP hinges on two post-translational modifications: phosphorylation and carboxylation. Depending on the above-noted modifications, various species of MGP may exist in circulation, each with their respective level of functionality. Emerging data suggest that dysfunctional species of MGP, markedly, dephosphorylated-uncarboxylated MGP, might find its application as biomarkers of microvascular health, and assist in clinical decision making with regard to initiation of vitamin K supplementation. Hence, in this review we summarized the current knowledge with respect to the role of MGP in the complex network of vascular calcification with concurrent inferences to CAD. In addition, we discussed the effects of warfarin use on MGP functionality, with concomitant implications to coronary plaque stability.


1994 ◽  
Vol 108 (6) ◽  
pp. 507-508 ◽  
Author(s):  
R. Benson-Mitchell ◽  
N. Tolley ◽  
C. B. Croft ◽  
D. Roberts

AbstractLipomas are common benign connective tissue tumours composed of adult adipose tissue. They are relatively rare in the upper aerodigestive tract, although they occur with considerable frequency in other areas, particularly in the subcutaneous tissues of the neck. Although there are several reports of this tumour occurring in the oropharynx, there is no recorded case of a lipoma of the tonsillar fossa. An 83-year-old man with a left tonsillar fossa lipoma is presented. Clinical presentation, management and a literature review are discussed.


1999 ◽  
Vol 82 (12) ◽  
pp. 1764-1767 ◽  
Author(s):  
Dean Cain ◽  
David Sane ◽  
Reidar Wallin

SummaryMatrix GLA protein (MGP) is an inhibitor of calcification in the arterial wall and its activity is dependent upon vitamin K-dependent γ-carboxylation. This modification is carried out by a warfarin sensitive enzyme system that converts specific Glu residues to γ-carboxyglutamic acid (GLA) residues. Recent studies have demonstrated that the γ-carboxylation system in the arterial wall, in contrast to that in the liver, is unable to use vitamin K as an antidote to warfarin.By use of immunohistochemistry we demonstrate that MGP is expressed in the arterial wall and immunocytochemistry localized the MGP precursors to the endoplasmic reticulum in vascular smooth muscle cells. Resting smooth vascular muscle cells in the aortic wall and proliferating cells from explants of the aorta have all the enzymes needed for γ-carboxylation of MGP. However, when compared to the liver system, expression of the enzymes of the γ-carboxylation system in vascular smooth muscle cells is different. Of particular interest is the finding that the specific activity of the warfarin sensitive enzyme vitamin K epoxide reductase is 3-fold higher in vascular smooth muscle cells than in liver. DT-diaphorase, which catalyses the antidotal pathway for vitamin K reduction in liver, is 100-fold less active in resting vascular smooth muscle cells than in liver. Data obtained from an in vitro γ-carboxylation system suggest that the antidotal pathway catalyzed by DT-diaphorase in the vessel wall is unable to provide the carboxylase with enough reduced vitamin K to trigger γ-carboxylation of MGP. This finding provides an explanation to the inability of vitamin K to work as an antidote to warfarin intoxication of the arterial wall. Therefore the vitamin K dependent γ-carboxylation system in the arterial wall share a common feature with the system in bone cells by being unable to utilize vitamin K as an antidote.


2014 ◽  
Vol 21 (2) ◽  
pp. 153-158 ◽  
Author(s):  
Na-Ri Lee ◽  
Tae-Hun Go ◽  
Sang-Mee Lee ◽  
Seong-Yun Jeong ◽  
Geun-Tae Park ◽  
...  

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