Structural requirements of ligands for the oxysterol liver X receptors LXRα and LXRβ
Structural requirements of ligands for the oxysterol liver X receptors LXRα and LXRβ
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DOI：
10.1073/pnas.96.1.266
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发表时间：
1999-01-05
影响因子：
11.1
通讯作者：
Mangelsdorf, DJ
中科院分区：
文献类型：
--
作者：
Janowski, BA;Grogan, MJ;Mangelsdorf, DJ
LXR α和β是调节几种重要脂质代谢的核受体，包括胆固醇和胆汁酸。以前，我们已经提出LXR通过与特定的天然存在的氧化固醇（包括22（R）-羟基胆固醇，24（S）-羟基胆固醇和24（S），25-环氧胆固醇）相互作用来调节这些途径。使用的配体结合试验，采用闪烁接近技术，以规避与测定极疏水配体相关的许多问题，我们现在证明，这些氧化固醇直接结合到LXR在体内发生的浓度。为了进一步表征有效LXR配体所需的结构决定因素，我们合成并测试了一系列与LXR结合和转录激活的相关化合物。这些研究表明，甾醇侧链的位置特异性单氧化是LXR高亲和力结合和活化所必需的。增强的结合和活化也可以通过使用在侧链中充当氢键受体的24-氧代配体来实现。此外，在甾醇B环上引入氧导致具有LXR α-亚型选择性的配体。这些结果支持了天然存在的氧固醇是LXR的生理配体的假设，并表明合理的，基于结构的方法可用于设计有效的LXR配体用于药理学用途。
LXR alpha and -beta are nuclear receptors that regulate the metabolism of several important lipids, including cholesterol and bile acids. Previously, we have proposed that LXRs regulate these pathways through their interaction with specific, naturally occurring oxysterols, including 22(R)-hydroxycholesterol, 24(S)-hydroxycholesterol, and 24(S),25-epoxycholesterol. Using a ligand binding assay that incorporates scintillation proximity technology to circumvent many of the problems associated with assaying extremely hydrophobic ligands, we now demonstrate that these oxysterols bind directly to LXRs at concentrations that occur in vivo. To characterize further the structural determinants required for potent LXR ligands, we synthesized and tested a series of related compounds for binding to LXRs and activation of transcription. These studies revealed that position-specific monooxidation of the sterol side chain is requisite for LXR high-affinity binding and activation. Enhanced binding and activation can also be achieved through the use of 24-oxo ligands that act as hydrogen bond accepters in the side chain. In addition, introduction of an oxygen on the sterol B-ring results in a ligand with LXR alpha-subtype selectivity. These results support the hypothesis that naturally occurring oxysterols are physiological ligands for LXRs and show that a rational, structure-based approach can be used to design potent LXR ligands for pharmacologic use.