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

本文分析了新合成的维生素K-4(MK-4)在哺乳动物体内的生理作用，以及维生素K-I抗炎和调节类固醇合成的分子机制。以二氢叶醌(DK1)为维生素K来源，建立了肝外组织低维生素K、无出血症状的动物模型，并对其表型进行了分析。饲喂DK1组大鼠血浆骨钙素水平明显升高，骨钙素是骨代谢指标之一。而血浆钙水平无明显变化。因此，DK1饲喂对成骨细胞的分化有促进作用，而不是翻转成骨。II.为了阐明睾丸MK-4在类固醇合成中的直接作用，我们给亚慢性维生素K缺乏大鼠注射脂多糖，没有任何出血，并分析了睾丸中睾酮的产生。结果表明，内毒素可抑制睾丸MK-4的合成，降低Cyp11a基因的表达，并与MK-4浓度呈正相关。这些结果表明，睾丸MK-4具有抗炎作用，以维持正常的类固醇合成。利用小鼠巨噬细胞来源的细胞分析了维生素K抗炎的分子机制。MK-4能显著降低脂多糖刺激的IL-1β、IL-6和肿瘤坏死因子α的表达，并呈剂量依赖关系。经MK-4处理的条件培养液也具有减少炎性细胞因子表达的活性。提示MK-4代谢产物或MK-4处理细胞分泌的物质具有抗炎作用。

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.