Molecular Basis of Intracellular Cholesterol Homeostasis

在本资助期内，关于载脂蛋白与细胞相互作用对高密度脂蛋白组装的机制和生理相关性的研究成果总结如下。降低高密度脂蛋白药物普罗布考对高密度脂蛋白组装反应的抑制作用在小鼠体内重现，并证明该反应是血浆高密度脂蛋白的主要来源（BBA 1485: 199,2000），而该反应的主要器官是肝脏（ATVB 21,394, 2001）。在小鼠单核白血病细胞RAW 264中，cAMP诱导高密度脂蛋白的组装与载脂蛋白与细胞的物理结合并行，abca1 mRNA的10组增加（生物化学39,11092,2000）。通过对THP-1细胞和成纤维细胞的实验，我们发现ABCA1并不是HDL组装的绝对必需，而caveolin-1在胆固醇进入HDL的过程中起着重要作用，黄体酮通过一种未知的机制抑制了这一途径（JLR 41,1952,2000; jbc277,7929,2002; BBA 1532,173,2001）。膜筏被认为是高密度脂蛋白组装的一个地点（JLR41, 894, 2000）。当ABCA1被转染并在HEK293中功能性表达时，该蛋白显示出一个信号肽被切割，n端暴露于外部（BBRC 283, 1019,2001）。在一篇综述文章（BBA 1529, 231, 2000）中总结了上述部分结果。

During the current grant term, research accomplishment is summarized below for the mechanism and physiological relevance of HDL assembly by apolipoprotein-cell interaction. Inhibition of the HDL assembly reaction by an HDL-lowering drug probucol was reproduced in mice in vivo, and demonstrated the this reaction is a main source of plasma HDL (BBA 1485 : 199, 2000) and the main organ for the reaction is the liver (ATVB 21, 394, 2001). Assembly of HDL in mouse monocytic leukemia cell RAW 264 is induced by cAMP in parallel with physical binding of apolipoprotein to the cell, and with 10-tome increase of abca1 mRNA (Biochemistry 39, 11092, 2000). From the experiments with THP-1 cells and fibroblasts, it was revealed that ABCA1 is not absolute requirement for the HDL assembly, that caveolin-1 plays an important role in incorporation of cholesterol into the HDL, and that progesterone inhibits this pathway by an unknown mechanism (JLR 41, 1952, 2000 ; JBC277, 7929, 2002 ; BBA 1532, 173, 2001). Membrane raft was suggested to be a site for the HDL assembly (JLR41, 894, 2000). When ABCA1 is transfected and functionally expressed in HEK293, the protein was shown with a signal peptide cleaved and the N-terminal exposed to outside (BBRC 283, 1019, 2001). A part of the results above is summarized in a review article (BBA 1529, 231, 2000).