Studies on Regulatory Mechanism of Secretion of VLDL

需要建立动脉粥样硬化的治疗和预防方法以预防心脏病。特别地，基于VLDL从肝脏分泌到血液中的减少的预防方法被认为对VLDL-和LDL-高脂血症都有效。基于此，我们对与载脂蛋白B-100降解调控有关的ER-60进行了研究。ER-60的活性通过与钙连接蛋白的管腔结构域结合来调节，钙连接蛋白是内质网的凝集素样分子伴侣。为了鉴定ER-60与钙连接蛋白结合的位点，确定了ER-60的结构域结构。ER-60由四个结构域a、B、B'和a'组成。在结构域中，B'是与calnexin结合所必需的。以往的研究表明，在HepG 2细胞中，ER-60与载脂蛋白B-100和BiP均结合。在这项研究中，BiP被证明对ER-60的活性具有刺激作用。另外，我们发现大豆7S球蛋白，其对载脂蛋白100-B的合成具有降低作用，抑制ER-60的转录。

Establishment of therapeutics and prevention methods of an atherosclerosis is demanded to prevent a cardiac disease. Especially, the preventing method based on decrease in the VLDL secretion from liver into blood is thought effective in both VLDL- and LDL-hyperlipidemia. Based on these ideas, ER-60, which is concerned to the regulatory degradation of apolipoprotein B-100, was studied. The activity of ER-60 is regulated by a binding with the lumen domain of calnexin, which is a lectin-like molecular chaperone of endoplasmic reticulum. To identify the site of ER-60 for the binding with calnexin, the domain structure of ER-60 was determined. ER-60 was shown to be composed of four domains, a, b, b' and a'. Among domains, b' was essential for the binding with calnexin. In previous study, it has been shown that ER-60 bound to both apolopoprotein B-100 and BiP in HepG2 cell. In this study, BiP was shown to have stimulating effect on the activity of ER-60. In addition, we found that a soy 7S globulin, which has a lowering effect on synthesis of apolipoprotein 100-B, depresses the transcription of ER-60.