Physiological role of vitamin K2 (manaquinone-4) that is converted from other vitamin K analogue in animal organs

本文分析了哺乳动物体内新合成的甲基萘醌-4（MK-4）的生理作用，以及维生素K抗炎和调节类固醇生成的分子机制。I.以二乙酰基醌（dK 1）为维生素K源，建立了肝外组织维生素K含量低而无出血症状的动物模型，并对其表型进行了分析。dK 1组大鼠血浆骨钙素水平显著升高，而dK 1组大鼠血浆骨钙素水平显著升高。另一方面，血浆钙水平未发生变化。因此，dK 1的饲养可能会促进成骨细胞的分化，而不是骨的翻转。二.为了阐明睾丸MK-4在类固醇生成中的直接参与，我们给亚慢性维生素K缺乏大鼠注射脂多糖而不出血，并分析睾丸中睾酮的产生。结果表明，LPS处理后睾丸组织中睾酮的合成和Cyp 11 a基因的表达随MK-4浓度的增加而降低。提示睾丸MK-4具有抗炎作用，维持正常的类固醇合成。三.本研究以小鼠巨噬细胞为模型，探讨了维生素K抗炎作用的分子机制。MK-4可显著降低LPS刺激的IL-1β、IL-6和TNFα mRNA的表达，并呈剂量依赖性。用MK-4处理的条件培养基也具有减少炎性细胞因子表达的活性。这些结果表明MK-4代谢产物或由MK-4处理的细胞分泌的某种物质显示出抗炎作用。

We analyzed the physiological role of de novo synthesized menaquinone-4 (MK-4) in mammal, and also molecular mechanism of anti-inflammation and regulation of steroidogenesis by vitamin K. I. We developed the model that has low vitamin K in extra-hepatic tissues without any bleeding sym ptom by feeding of dihydrophylloquinone (dK1) as a vitamin K source, and analyzed its phenotype. The plasma osteocalcin level that is one of bone metabolic markers was significantly increased in dK1 feeding group. On the other hand, plasma calcium level was not changed. Therefore dK1 feeding coup d enhance the differentiation of osteoblast not turn over of bone. II. To clarify the direct involvement of testis MK-4 in steroidogenesis, we administered lipopolysaccharide to the subchronic vitamin K deficient rats without any bleeding and analyzed testosterone production in testis. As a result, the synthesis of testosterone and gene expression of Cyp11a was decreased by LPS treatment depending on testis MK-4 concentration. These results indicate that testis MK-4 shows anti-inflammation effect to keep the normal steroidogenesis. III. We analyzed the molecular mechanism of the anti-inflammation by vitamin K using mouse macrophage derived cells. MK-4 significantly reduced IL-1β, IL-6, and TNFα mRNA stimulated by LPS treatment dose-dependent manner. Conditioned medium treated with MK-4 also has a reducing activity of inflammatory cytokine expression. These results suggested that MK-4 metabolite or something secreted from MK-4 treated cells show anti-inflammatory effect.