Clarification of a novel physiological function of menaquinone-4 (vitamin K2), a postulated active form of vitamin K in various tissues

澄清 Menaquinone-4（维生素 K2）的新生理功能，这是维生素 K 在多种组织中的一种假定活性形式

基本信息

批准号：
13660115
负责人：
KOMAI Michio
金额：
$ 2.24万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Phylloquinone (vitamin K1=VK1) and the menaquinones (MK-n, or vitamin K2=VK2) are naturally occurring forms of vitamin K. Most of the menaquinones are synthesized by micro-organisms, but we have reported that MK-4 is usual in being synthesized by the conversion of orally ingested VK1 or menadione (=VK3) in the major tissues of germfree rats and mice which lack their intestinal microflora. This result denies Martius' theory that described the participation of bacterial enzyme of the intestinal flora to this conversion. Recently MK-4 has been attracted the attention of researchers due to its specific physiological action such as apoptotic activity on osteoclast cells and leukemia cells, etc. that is beneficial for the maintainance of our healthy quality of life. Therefore, we considered that MK-4 may have a specific novel function in various tissues of animals besides of coagulation in the liver and Gla-protein related action in the other tissues which all analogues of vitamin Ks have.In … More order to elucidate this hypothesis, we tried to identify genes of which expression is up-or down-regulated under VK deficient condition. DNA microarray technique is a very powerful tool to see the pofile of gene expression simultaneously. Two groups of germfree rats fed VK deficient or VK1 supplemented diet for eight days were sacrificed, and blood and tissue samples were deprived. The results of blood coagulation time (prothrombin time and activated-partial thromboplastin time) and the measurement of VK levels in various tissues supported that rats fed deficient diet showed much more sevefe VK deficient symptoms.The profile of gene expression in the liver, brain, and testis showed that the expression of diverse genes was affected under vitamin K deficiency. The series of genes which were markedly up-regulated in VK deficient liver belonged to a particular group of protein, i.e., acute phase proteins. This result was consistent with our previoous observations that VK deficient germfree mice had acute histological changes in the liver and muscle. Dietary VK1 has an anti-inflammatory effect in the LPS (lipopolysaccharide)-stimulated system in vivo, probably through its conversion to MK-4, because we observed that LPS-stimulated IL-6 expression in the primary cultured spleen was significantly inhibited by the addition of MK-4 to the culture medium rather than VK1. In conclusion, any kind of dietary VK that is considered to convert to MK-4 in various tissues has an anti-inflammatory role in the rodents and probably in humans, though detailed mechanisms involved in the effect of MK-4 should be clarified further. Less

叶绿醌（维生素 K1=VK1）和甲基萘醌（MK-n，或维生素 K2=VK2）是维生素 K 的天然形式。大多数甲基萘醌是由微生物合成的，但我们已报道 MK-4 是常见的通过口服摄入的 VK1 或甲萘醌 (=VK3) 在缺乏肠道的无菌大鼠和小鼠的主要组织中转化而合成这一结果否定了Martius的理论，该理论描述了肠道菌群的细菌酶参与了这种转化，最近MK-4因其特定的生理作用（例如对破骨细胞和白血病细胞的凋亡活性）而引起了研究人员的关注。因此，我们认为MK-4除了在肝脏中的凝血作用和在其他方面与Gla蛋白相关的作用外，可能在动物的各个组织中具有特定的新功能。为了阐明这一假设，我们试图鉴定在 VK 缺乏条件下表达上调或下调的基因。DNA 微阵列技术是观察 POFILE 的非常强大的工具。同时处死两组喂食缺乏 VK 或补充 VK1 饮食的无菌大鼠，并采集血液和组织样本，检测凝血时间（凝血酶原时间和凝血酶原时间）。激活部分凝血活酶时间）和各组织中 VK 水平的测量表明，喂食缺乏饮食的大鼠表现出更严重的 VK 缺乏症状。肝脏、大脑和睾丸中的基因表达谱表明，不同基因的表达在维生素 K 缺乏的肝脏中显着上调的一系列基因属于一组特定的蛋白质，即急性期蛋白质，这一结果与我们之前观察到的 VK 缺乏的无菌状态一致。小鼠的肝脏和肌肉发生了急性组织学变化，膳食 VK1 在体内 LPS（脂多糖）刺激的系统中具有抗炎作用，可能是通过其转化为 MK-4，因为我们观察到 LPS 刺激的 IL-6。在培养基中添加 MK-4 而不是 VK1 会显着抑制原代培养脾脏中的表达。总之，任何种类的膳食 VK 都被认为会转化为 MK-4。尽管 MK-4 的作用的详细机制尚需进一步阐明，但在啮齿类动物甚至人类中也可能具有抗炎作用。