Vitamin K-Dependent Carboxylation of Osteocalcin: Friend or Foe?
Vitamin K-Dependent Carboxylation of Osteocalcin: Friend or Foe?
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DOI：
10.3945/an.112.001834
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发表时间：
2012-03-01
影响因子：
9.3
通讯作者：
Booth, Sarah L.
中科院分区：
文献类型：
--
作者：
Gundberg, Caren M.;Lian, Jane B.;Booth, Sarah L.
骨钙素来源于成骨细胞合成，并沉积到骨中或释放到循环中，在循环中它与骨形成的组织学测量相关。3个维生素K依赖性γ-羧基谷氨酸残基的存在对于骨钙素的结构至关重要，骨钙素似乎调节骨矿物质的成熟。在人类中，未被γ-羧基化的循环骨钙素的百分比（ucOC百分比）被用作维生素K状态的生物标志物。相反，当ucOC未校正总骨钙素时，该测量的解释受到成骨细胞活性的混淆，与维生素K无关。使用ucOC百分比的观察性研究得出结论，维生素K不足导致年龄相关的骨质流失。然而，临床试验并没有为一般人群补充维生素K会降低骨丢失或骨折风险的建议提供全面支持。最近，使用动物模型进行的体外和体内研究结果表明，ucOC是一种在葡萄糖代谢中具有积极作用的活性激素。由此推断，降低ucOC的维生素K会产生不利影响。然而，在人类中，这一假设并没有得到有限数据的支持，也没有得到骨钙素化学的支持。总之，骨钙素在骨和葡萄糖代谢中的具体功能尚未阐明。高级Nutr. 3：149 - 157，2012.
Osteocalcin originates from osteoblastic synthesis and is deposited into bone or released into circulation, where it correlates with histological measures of bone formation. The presence of 3 vitamin K-dependent gamma carboxyglutamic acid residues is critical for osteocalcin's structure, which appears to regulate the maturation of bone mineral. In humans, the percentage of the circulating osteocalcin that is not gamma-carboxylated (percent ucOC) is used as a biomarker of vitamin K status. In contrast, when ucOC is not corrected for total osteocalcin, the interpretation of this measure is confounded by osteoblastic activity, independent of vitamin K. Observational studies using percent ucOC have led to the conclusion that vitamin K insufficiency leads to age-related bone loss. However, clinical trials do not provide overall support for the suggestion that vitamin K supplementation of the general population will reduce bone loss or fracture risk More recently, results from in vitro and in vivo studies using animal models indicate that ucOC is an active hormone with a positive role in glucose metabolism. By inference, vitamin K, which decreases ucOC, would have a detrimental effect. However, in humans this hypothesis is not supported by the limited data available, nor is it supported by what has been established regarding osteocalcin chemistry. In summary, the specific function of osteocalcin in bone and glucose metabolism has yet to be elucidated. Adv. Nutr. 3: 149-157, 2012.