概括
肝素释放与纤维细胞表面受体结合的低密度脂蛋白 (LDL),区分初始结合与内细胞分裂. 这种LDL受体机制对于细胞吸收至关重要,在家族性高胆固醇血症中缺席.
科学领域:
- 细胞生物学 细胞生物学
- 生物化学 生物化学
- 分子医学是分子医学.
背景情况:
- 细胞吸收低密度脂蛋白 (LDL) 对于胆固醇稳态至关重要.
- 这种LDL受体调解了LDL的内部化到细胞中.
- 家族性高胆固醇血症是一种遗传性疾病,其特征是由于缺陷的LDL受体导致LDL水平高.
研究的目的:
- 研究人类纤维细胞结合和吸收LDL的机制.
- 要区分细胞表面结合和LDL的内细胞分裂.
- 评估LDL受体在细胞LDL吸收中的作用.
主要方法:
- 使用125I标记的LDL和正常的人类纤维细胞.
- 使用肝素释放与细胞表面结合的LDL.
- 在37摄氏度和4摄氏度进行实验.
- 利用来自同卵性家族高胆固醇血症患者的突变纤维细胞.
- 将肝素与α-甲基-D-mannopyranoside对3H-concanavalin A释放的作用进行比较.
主要成果:
- 氨酸有效地从正常纤维细胞的表面释放了125I-LDL,表明可逆结合.
- 确定了LDL吸收的两部分过程:快速的,可释放氨酸的表面结合和较慢的,可释放氨酸的耐氨酸内细胞分裂.
- 在4摄氏度时,LDL内部化 (内细胞化) 不发生,而表面结合仍然存在.
- 来自家族性高胆固醇血症患者的纤维细胞没有显示氨酸可释放的LDL结合,证实了功能性LDL受体的缺失.
- 肝素从各自的受体特别释放LDL,而不是康卡纳瓦林A.
结论:
- 肝素作为一种有价值的工具,可以区分LDL结合和内细胞形成.
- 纤维细胞通过LDL受体吸收LDL是一种受体介导的吸附性内细胞分裂的模型.
- 在LDL受体通路中的缺陷,如在家族性高胆固醇血症中所见,严重损害了细胞LDL吸收.
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