RECEPTOR-DEPENDENT HYDROLYSIS OF CHOLESTERYL ESTERS CONTAINED IN PLASMA LOW-DENSITY LIPOPROTEIN
RECEPTOR-DEPENDENT HYDROLYSIS OF CHOLESTERYL ESTERS CONTAINED IN PLASMA LOW-DENSITY LIPOPROTEIN
复制标题
DOI：
10.1073/pnas.72.8.2925
复制
发表时间：
1975-01-01
影响因子：
11.1
通讯作者：
GOLDSTEIN, JL
中科院分区：
文献类型：
--
作者：
BROWN, MS;DANA, SE;GOLDSTEIN, JL
人血浆低密度脂蛋白中所含胆固醇酯的选择性放射性标记允许研究这些分子在单层和培养的人成纤维细胞提取物中的代谢。在正常细胞单层中，低密度脂蛋白与其细胞表面受体结合后，脂蛋白中所含的[3H]胆固醇亚油酸酯迅速水解，释放的[3H]胆固醇在细胞内蓄积。降解过程的化学计量表明，蛋白质和胆固醇酯组分的脂蛋白水解平行。孵育完整的成纤维细胞与氯喹，一种已知的抑制剂的溶酶体降解过程，抑制脂蛋白结合的胆固醇酯的水解。来自患有纯合子形式的家族性高胆固醇血症的受试者的成纤维细胞缺乏功能性低密度脂蛋白受体，因此当该脂蛋白以低浓度存在于培养基中时不能摄取该脂蛋白，因此不能水解脂蛋白结合的[3H]胆固醇亚油酸酯。然而，从这些突变体细胞的无细胞提取物能够水解脂蛋白结合的[3H]胆固醇亚油酸酯在相同的快速速率作为正常细胞培养时，在酸性pH值。这些数据说明了低密度脂蛋白受体和溶酶体酸水解酶在低密度脂蛋白的代谢利用培养的人成纤维细胞的重要作用。
Selective radioactive labeling of the cholesteryl esters contained within human plasma low density lipoprotein has allowed the study of the metabolism of these molecules in monolayers and extracts of cultured human fibroblasts. In monolayers of normal cells, binding of low density lipoprotein to its cell surface receptor was followed by rapid hydrolysis of the [3H]cholesteryl linoleate contained within the lipoprotein and accumulation of the liberated [3H]cholesterol within the cell. The stoichiometry of the degradative process suggested that the protein and cholesteryl ester components of the lipoprotein were hydrolyzed in parallel. Incubation of intact fibroblasts with chloroquine, a known inhibitor of lysosomal degradative processes, inhibited the hydrolysis of the lipoprotein-bound cholesteryl esters. Fibroblasts from subjects with the homozygous form of familial hypercholesterolemia, which lack functional low density lipoprotein receptors and thus are unable to take up this lipoprotein when it is present in the culture medium at low concentrations, were therefore unable to hydrolyze the lipoprotein-bound [3H]cholesteryl linoleate. However, cell-free extracts from these mutant cells were capable of hydrolyzing the lipoprotein-bound [3H]cholesteryl linoleate at the same rapid rate as normal cells when incubated at acid pH. These data illustrate the essential role of the low density lipoprotein receptor and of lysosomal acid hydrolases in the metabolic utilization of low density lipoproteins by cultured human fibroblasts.