Fidge N, Leonard-Kanevsky M, Nestel P
Biochim Biophys Acta. 1984 Apr 18;793(2):180-6. doi: 10.1016/0005-2760(84)90319-9.
Several studies have shown that high-density lipoprotein stimulates steroidogenesis in rat tissues which have been treated with pituitary hormones. To determine whether these hormones can directly affect receptors for high-density lipoprotein, we have incubated cultured rat adrenal cortical cells with 125I-labeled human HDL3 and studied the effect of corticotrophin on the binding, internalization and degradation of this lipoprotein. ACTH stimulated all these parameters of HDL metabolism in a dose-dependent manner with maximal stimulation occurring between 10 and 20 mU/ml. The effect was temperature-dependent and showed target cell specificity. Although the hormone stimulated binding and internalization 5-6-fold, degradation of HDL3 was substantially less (2-fold) than anticipated. This suggests that the lipoprotein was taken up by vesicles resembling receptosomes which escape fusion with lysosomes; thus degradation of entrapped particles does not occur, while transfer of cholesterol for steroidogenesis is unaffected.
多项研究表明，高密度脂蛋白可刺激经垂体激素处理的大鼠组织中的类固醇生成。为了确定这些激素是否能直接影响高密度脂蛋白的受体，我们用125I标记的人HDL3孵育培养的大鼠肾上腺皮质细胞，并研究促肾上腺皮质激素对这种脂蛋白的结合、内化和降解的影响。促肾上腺皮质激素以剂量依赖的方式刺激HDL代谢的所有这些参数，最大刺激发生在10至20 mU/ml之间。该效应是温度依赖性的，并表现出靶细胞特异性。尽管该激素刺激结合和内化5至6倍，但HDL3的降解比预期的要少得多（2倍）。这表明脂蛋白被类似于受体小体的囊泡摄取，这些囊泡逃避与溶酶体的融合；因此，被困颗粒不会发生降解，而用于类固醇生成的胆固醇转移不受影响。
