人体培养细胞的低密度脂蛋白受体功能研究

Studies on LDL receptor activities in human cultured cells

本文介绍培养的人体细胞低密度脂蛋白受体功能的测定方法,报告用此法测定的正常值及有关动力学,某些生理病理影响因素等的研究结果。正常人皮肤纤维母细胞对I-LDL的结合,内移和降解分别为66±11,350±70和1710±279ng/mg细胞蛋白(均值±标准误)。动力学研究证实受体功能与培养液中I-LDL浓度呈可饱和性指数曲线关系,一例正常人纤维母细胞37℃时的最大高亲和性结合为280ng/mg细胞蛋白,达到半数最大结合量所需I-LDL的浓度为20ng/ml。一例家族性高胆固醇血症患者的受体功能仅为正常值的2~5%。Dibutyryl-cAMP可抑制人皮肤纤维细胞对I-LDL的结合、摄取和降解,且呈浓度依赖性关系。

LDL receptor activities in human cultured cells were measured by Goldstein and Brown’s method.I-LDL binding,internalization and degradation values in healthy human skin fibroblasts were 66±11,350±70,and 1710±279 ng/mg cell protein respectively.kinetic studies showed a saturable exponential curve correlation between LDL receptor activities andI-LDL concentrations in medium.The maximal high affinity binding of a normal human(B max)at 37℃was 280 ngI-LDL/mg cell protein and the appar ent K mvalue 20μg/ml.Ficroblasts from a homozygous familial hypercholesterolemic patient yielded LDL receptor activities only equal to 2—5%of normal.Dibutyryl-cAMP inhibited the receptor mediatedI-LDL binding,internalization and degradation in human skin fibroblasts,and had a dose-effect relationship.