REGULATION OF 1,25-DIHYDROXYVITAMIN-D3 RECEPTORS BY VITAMIN-D ANALOGS IN CULTURED MAMMALIAN-CELLS
REGULATION OF 1,25-DIHYDROXYVITAMIN-D3 RECEPTORS BY VITAMIN-D ANALOGS IN CULTURED MAMMALIAN-CELLS
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DOI：
10.1210/endo-117-5-2203
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发表时间：
1985-01-01
期刊：
影响因子：
4.8
通讯作者：
FELDMAN, D
中科院分区：
文献类型：
--
作者：
COSTA, EM;HIRST, MA;FELDMAN, D
猪肾细胞系（LLC-PK 1）已被证明具有1，25-二羟基维生素D3 [1，25-（OH）2D 3]受体，并对维生素D代谢物表现出功能反应。在这里，我们报告说，这些受体似乎进行同源上调1，25-（OH）2D 3和其他维生素D类似物。在其他细胞系中也观察到这种现象，包括人皮肤成纤维细胞和人乳腺癌细胞（MCF-7）。用活性激素或维生素D类似物治疗导致1，25-（OH）2D 3受体数量的显著增加（200-400%），而不改变受体对激素的亲和力。上调的受体，如基础受体，具有约0.04 nM的表观Kd，并在高渗蔗糖梯度上在3.3S处沉积。此外，在0.18 M KCl下，来自对照和处理细胞的总受体的约50%与DNA-纤维素和DNA-纤维素结合。这些结果表明，上调的受体类似于经典的1，25-（OH）2D 3受体。虽然达到最大受体增量所需的时间是16-20小时，有一个快速的组成部分，在5分钟内观察到的上升。激素去除后的最大效果持续4-6小时。增加的结合不是可提取性的差异受体定位的结果。1，25-（OH）2D 3、1，24，25-三羟基维生素D3、24，25-（OH）2D 3和25-羟基维生素D3均将受体结合增加至相似水平，所需剂量密切反映了各种代谢物对受体的亲和力。用RNA合成抑制剂放线菌素D处理细胞表明受体的增加部分依赖于RNA合成。来自维生素D依赖性佝偻病II型患者的突变皮肤成纤维细胞，含有无反应的1，25-（OH）2D 3受体，未能表现出在正常细胞中观察到的特征性上调。综上所述，这些结果表明，维生素D代谢物调节1，25-（OH）2D 3受体的数量，部分通过受体占有率，更重要的是，通过受体介导的诱导机制。
The pig kidney cell line (LLC-PK1) has been shown to possess 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] receptors and to exhibit functional responses to vitamin D metabolites. Here we report that these receptors appear to undergo homologous up-regulation by 1,25-(OH)2D3 and other vitamin D analogs. This phenomenon was also observed in other cell lines, including human skin fibroblasts and human mammary cancer cells (MCF-7). Treatment with active hormone or vitamin D analogs results in a substantial increase (200-400%) in the number of 1,25-(OH)2D3 receptors without altering the affinity of receptor for hormone. The up-regulated receptor, like the basal receptor, has an apparent Kd of about 0.04 nM and sediments at 3.3S on hypertonic sucrose gradients. In addition, approximately 50% of the total receptors from both control and treated cells bind to DNA-cellulose and elute at 0.18 M KCl. These results indicate that the up-regulated receptor is similar to the classical 1,25-(OH)2D3 receptor. While the time necessary to achieve the maximal receptor increment is 16-20 h, there is a rapid component in the rise observed within 5 min. The maximal effect persists for 4-6 h after hormone removal. The increased binding is not a result of differential receptor localization of extractability. 1,25-(OH)2D3, 1,24,25-trihydroxyvitamin D3,24,25-(OH)2D3 and 25-hydroxyvitamin D3 all increase receptor binding to similar levels, and the dose required closely reflects the affinities of the various metabolites for the receptor. Treatment of cells with the RNA synthesis inhibitor actinomycin D indicates that the increase in receptors is partially dependent on RNA synthesis. Mutant skin fibroblasts from patients with vitamin D-dependent rickets type II, containing nonresponsive 1,25-(OH)2D3 receptors, failed to exhibit the characteristic up-regulation observed in normal cells. Taken together, these results indicate that vitamin D metabolites regulate the number of 1,25-(OH)2D3 receptors in part by receptor occupancy and, more importantly, by a receptor-mediated induction mechanism.