VITAMIN-D-3 RETINOID-X-RECEPTOR DIMERIZATION, DNA-BINDING, AND TRANSACTIVATION ARE DIFFERENTIALLY AFFECTED BY ANALOGS OF 1,25-DIHYDROXYVITAMIN D-3
VITAMIN-D-3 RETINOID-X-RECEPTOR DIMERIZATION, DNA-BINDING, AND TRANSACTIVATION ARE DIFFERENTIALLY AFFECTED BY ANALOGS OF 1,25-DIHYDROXYVITAMIN D-3
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DOI：
10.1210/me.9.12.1814
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发表时间：
1995-12-01
影响因子：
--
通讯作者：
FREEDMAN, LP
中科院分区：
文献类型：
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作者：
CHESKIS, B;LEMON, BD;FREEDMAN, LP
已经合成了许多1，25-二羟基维生素D-3 [1，25-（OH）（2）D-3]的类似物，其作为比天然配体更有效的细胞分化诱导剂和细胞生长抑制剂;同时，许多类似物具有降低的高钙特性。这种组合使这些化合物成为临床应用的有吸引力的候选物。然而，类似物的作用机制尚不清楚。潜在地，类似物可以更容易地被吸收，更缓慢地被分解代谢，或者对维生素D受体（VDR）具有更高的结合亲和力。1，25-（OH）（2）D-3的类似物也可以差异调节VDR的一种或多种活性，即二聚化、DNA结合和/或转录调节。为了直接检查后一种可能性，我们使用了二聚化和DNA结合动力学的灵敏测定、表面等离子体共振，并在此报道了三种1，25-（OH）（2）D-3类似物，1，25-（OH）（2）-16-烯-23-炔-D-3、1，25-（OH）（2）-16-烯-23-炔-26，27-二高-D-3和1，25-（OH）（2）-26，27-六氟-16-烯-23-炔-D-3，都赋予了VDR-类维生素A X受体异二聚化和DNA与特定维生素D反应元件结合相对于天然配体的不同速率和平衡常数。作为对六氟类似物的响应，VDR与DNA结合的表观Kd显著低于1，25-（OH）（2）D-3，相应地，来自响应性报告物的体内反式激活更大。有趣的是，溶液异源二聚化不受这种类似物的影响。这些结果表明，维生素D类似物确实通过在VDR水平直接和差异地作用而赋予生物学效应，并且特定的维生素D类似物可以作用于不同的受体功能。
A number of analogs of 1,25-dihydroxyvitamin D-3 [1,25-(OH)(2)D-3] have been synthesized that act as more potent inducers of cellular differentiation and inhibitors of cell growth than the natural ligand; at the same time, many of the analogs have reduced hypercalcemic properties. This combination makes these compounds attractive candidates for clinical use. The mechanism by which the analogs act, however, is unclear. Potentially, the analogs could be taken up more readily, be more slowly catabolized, or have higher binding affinities for the vitamin D receptor (VDR). Analogs of 1,25-(OH)(2)D-3 could also differentially modulate one or more of the activities of VDR, namely dimerization, DNA binding, and/or transcriptional regulation. To directly examine this latter possibility, we used a sensitive assay for the kinetics of dimerization and DNA binding, surface plasmon resonance, and report here that three 1,25-(OH)(2)D-3 analogs, 1,25-(OH)(2)-16-ene-23-yne-D-3, 1,25-(OH)(2)-16-ene-23-yne-26,27-di homo-D-3, and 1,25-(OH)(2)-26,27-hexafluoro-16-ene-23-yne-D-3, all confer distinct rate and equilibrium constants for VDR-retinoid X receptor heterodimerization and DNA binding to a specific vitamin D response element relative to the natural ligand. In response to the hexafluoro analog, the apparent K-d for DNA binding by VDR was significantly lower than that for 1,25-(OH)(2)D-3, and correspondingly, in vivo transactivation from a responsive reporter was greater. Interestingly, solution heterodimerization was not affected by this analog. These results suggest that vitamin D analogs do indeed confer biological effects by acting directly and differentially at the level of VDR, and that specific vitamin D analogs can act on distinct receptor functions.