Homeostasis and its pathology of cellular lipid

1)小鼠白血病细胞株RAW 264中载脂蛋白相互作用部位的研究。为使该细胞表达与载脂蛋白的结合部位，并使高密度脂蛋白与细胞脂质结合，必须激活一种激酶。需要几个小时才能完全表达，而蛋白质合成的各种代谢抑制剂会抑制它的表达。因此，提出了一种膜蛋白(S)的贡献。有趣的是，在家族性高密度脂蛋白缺乏症中，ABC1的表达没有明显的差异。2)人类白血病细胞系THP-1中与高密度脂蛋白装配系统相关的细胞内胆固醇转运的研究。而THP-1细胞在分化前只通过载脂蛋白与细胞磷脂生成高密度脂蛋白，而在PMA诱导分化后，高密度脂蛋白富含胆固醇。ABC1和小窝蛋白-1都是由PMA诱导的，反义DNA选择性地降低产生的高密度脂蛋白中的胆固醇含量。因此，小凹蛋白-1负责将胆固醇掺入高密度脂蛋白))通过使用载脂蛋白-细胞相互作用的抑制剂普罗布考，在小鼠模型中研究高密度脂蛋白组装系统的生理相关性。普罗布考能迅速显著降低小鼠的高密度脂蛋白，而对包括ABC1在内的高密度脂蛋白相关蛋白的信息和高密度脂蛋白的清除没有明显的影响。普罗布考显著降低载脂蛋白和腹膜巨噬细胞对高密度脂蛋白的聚集，表明这是小鼠血浆高密度脂蛋白的主要来源。

We studied the HDL assembly system mediated by apolipoprotein-cell interaction by using three model systems.1) Study on the apolipoprotein interaction site in mouse leukemic cell line cells RAW 264. A kinase must be activated for this cell to express the binding site with apolipoprotein and to gegerate HDL with cellular lipid. It takes several hours for the full expression which is suppressed by various metabolic inhibitors for protein synthesis. Therefore, contribution of a membrane protein(s) is suggested. Interestingly, there was no apparent difference in expression of ABC1 which has been shown as a mutation site in familial HDL deficiencies.2) Study on intracellular cholesterol trafficking linked to the HDL assembly system in human leukemic cell line cells THP-1. While THP-1 cells gegerate HDL only with cellular phospholipid by apolipoprotein before differentiation, HDL is enriched with cholesterol after PMA induces differentiation. Both ABC1 and caveolin-1 are induced by PMA, and the antisense DNA selectively reduces cholesterol content in the HDL generated. Therefore, caveolin-1 is responsible for incorporation of cholesterol into the HDL.3) Study on physiological relevance of the HDL assembly system in a mouse model by using an inhibitor of the apolipoprotein-cell interaction, probucol. Mouse HDL is rapidly and remarkably decreased by probucol, while no significant change is demonstrated in the massages of HDL-relating proteins including ABC1 and in the HDL clearance. The HDL assembly by apolipoprotein and the peritoneal macrophage is markedly decreased by probucol, showing that this is a major source of plasma HDL in mice.