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Endocrine Abstracts (2015) 37 EP554 | DOI: 10.1530/endoabs.37.EP554

Obesity and cardiovascular endocrinology

Enzymes of the vitamin K cycle and progression of calcification in the vessel wall

Natascha Schweighofer1, Ariane Aigelsreiter2, Olivia Trummer1, Martina Graf-Rechberger2, Nicole Hacker1, Florian Iberer3, Doris Wagner3, Daniela Kniepeiss3, Philipp Stiegler3, Thomas Pieber1, Helmut Müller3 & Barbara Obermayer-Pietsch1

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1Department of Internal Medicine, Divison of Endocrinology and Metabolism, Medical University of Graz, Graz, Austria; 2Institute of Pathology, Medical University of Graz, Graz, Austria; 3Department of Surgery, Division of Transplantation Surgery, Medical University of Graz, Graz, Austria.


Calcification is a physiological process in bone but occurs also pathologically in the vasculature, favouring cardio- and cerebrovascular diseases (CVD). Vitamin K metabolites, particularly K1 and MK-4, are associated with decreased vascular calcification especially in patients with chronic kidney disease. We investigated the expression of components of the vitamin K cycle (VKC) and the MK-4 synthesis (MKS) in aorta and bone of 26 brain dead organ donors in order to identify differences in the expression pattern during atherosclerosis (AS) stages in aortic vascular tissue and to compare these profiles in both tissue types. Gene expression was performed using TaqMan gene expression assays with a LC480 system. Determination of calcification stage was done histologically: (0 (unaffected vessels), 1 (intima thickening), 2 (intima calcification)). VKC enzymes VKOR, VKORL1, GGCX and the chaperone calu and the enzymes NQO1 and UBIAD1, necessary for MKS are both expressed in aortic and bone tissue. In the aorta, gene expression of VKOR, VKORL1, and calu differed significantly between the three atherosclerotic stages (P=0.040; P=0.023 and P=0.038, respectively), whereas the expression of GGCX showed borderline significance (P=0.060). In bone, gene expression of VKC and the MKS proteins did not differ in respective AS stages. Comparison of bone and aorta showed only significant differences in gene expression of calu, GGCX and NQO1 in the last stage of intima calcification. We are able to demonstrate that bone and aorta express the components of vitamin K cycle and of MK-4 synthesis. We also show the existence of a different gene expression pattern in AS progression in bone and aorta. These data might lead to a more comprehensive insight into the role of vitamin K metabolising enzymes in vascular calcification.

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