Somatic Cell Genetic Mutants with Altered Cholesterol Metabolism and Altered Endocytosis of Low Density Lipoprotein

胆固醇代谢改变和低密度脂蛋白内吞作用改变的体细胞遗传突变体

基本信息

批准号：
60480142
负责人：
KUWANO Michihiko
金额：
$ 4.03万
依托单位：
Medical College of Oita
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

* Cellular uptake of low density lipoprotein (LDL) is mediated through receptor mediated endocytosis. Familiar hypercholesterolemia is closely linked to a number of mutations which distort the transport and processing of LDL receptors. To understand pathological changes in sterol metabolism in relation to receptor-mediated endocytosis of LDL, somatic cell mutants with altered sterol metabolism could be valuable. In particular, we try to propose such somatic cell mutants as model cell for abnormal sterol metabolic diseases. In this study we have studied three different mutants with altered receptor-mediated pathway of LDL.1. Monensin-resistant mutant of Chinese hamster overy (CHO) cells was defective in LDL binding to the cell surface receptor. This mutant showed higher sterol synthesis in the presence of LDL than CHO cells, and defective down-regulation of LDL receptors was observed in the mutant. N-linked glycosylation appeared to be altered among N- and O- linked oligosaccharides associated with LDL receptors in the mutant, suggesting altered function of Golgi apparatus.2. Monensin-resistant mutant of mouse Balb/3T3 cells was defective in endocytosis of LDL. This mutant also showed poor down-regulation of function of Golgi function appears to cause change(s) of membranous component, which may affect the endocytosis of LDL.3. Compactin-resistant mutant of Chinese hamster V79 cells was defective in LDL-receptor as well as endocytosis of LDL. LDL receptor synthesized in the mutant showed truncated molecules with aberrant O-linked sugar glycosylation.The turnover of mutant LDL receptors was much faster than that of wild ones, suggesting that the receptor molecules lacking O-linked sugars is sensitive to protease action.

* 低密度脂蛋白 (LDL) 的细胞摄取是通过受体介导的内吞作用介导的。常见的高胆固醇血症与许多扭曲 LDL 受体运输和加工的突变密切相关。为了了解与受体介导的 LDL 内吞作用相关的甾醇代谢的病理变化，甾醇代谢改变的体细胞突变体可能是有价值的。特别是，我们尝试提出此类体细胞突变体作为异常甾醇代谢疾病的模型细胞。在这项研究中，我们研究了三种不同的突变体，其受体介导的 LDL.1 途径发生了改变。中国仓鼠 Overy (CHO) 细胞的莫能菌素抗性突变体在 LDL 与细胞表面受体的结合方面存在缺陷。在 LDL 存在的情况下，该突变体表现出比 CHO 细胞更高的甾醇合成，并且在突变体中观察到 LDL 受体的下调有缺陷。突变体中与LDL受体相关的N-和O-连接寡糖中的N-连接糖基化似乎发生了改变，表明高尔基体的功能发生了改变。2．小鼠 Balb/3T3 细胞的莫能菌素抗性突变体在 LDL 内吞作用方面存在缺陷。该突变体还表现出高尔基体功能的较差下调，似乎导致膜成分的变化，这可能影响LDL的内吞作用。3。中国仓鼠V79细胞的Compactin抗性突变体在LDL受体和LDL内吞作用方面存在缺陷。突变体中合成的LDL受体显示出具有异常O-联糖糖基化的截短分子。突变体LDL受体的周转速度比野生LDL受体快得多，表明缺乏O-联糖的受体分子对蛋白酶作用敏感。