Evidence that ligand binding is a key determinant of Ah receptor-mediated transcriptional activity
Evidence that ligand binding is a key determinant of Ah receptor-mediated transcriptional activity
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DOI：
10.1016/j.abb.2005.07.014
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发表时间：
2005-10-01
影响因子：
3.9
通讯作者：
Perdew, GH
中科院分区：
文献类型：
--
作者：
Murray, IA;Reen, RK;Perdew, GH
芳烃受体 (AhR) 介导 2,3,7,8-四氯二苯并-对二恶英的生物活性。在没有配体结合的情况下，AhR 是否可以介导转录活性的增强尚未确定。使用猿猴病毒 40 使来自 AhR 缺失 (AhR-KO) 和野生型 (AhR-WT) 新生小鼠的肝细胞永生化。产生 AhR 的两个点突变体 A375I 和 A375F，以测试 AhR 需要配体结合才能表现出显着转录活性的假设，两种突变体均无法结合配体或在暴露于 AhR 配体的细胞中表现出增强的活性。在 AhR-KO 细胞中，ARNT 与 AhR-A375I 或 AhR-A375F 瞬时共表达后，这些突变体表现出显着的配体依赖性转录活性。然而，在 CV-1 细胞中（其他人之前已证明其含有相对较高水平的 AhR 配体），这些 AhR 突变体基本上不表现出组成型活性。这些结果表明，虽然 AhR 在没有配体结合的情况下可能表现出活性，但在许多细胞系中观察到的高组成型受体活性似乎是由于内源性 AhR 配体的存在。 (c) 2005 Elsevier Inc. 保留所有权利。
The aryl hydrocarbon receptor (AhR) mediates the biological activity of 2,3,7,8 -tetrachlorodibenzo-p-dioxin. Whether the AhR can mediate enhanced transcriptional activity in the absence of ligand binding has not been established. Hepatocytes from AhR-null (AhR-KO) and wild-type (AhR-WT) neonatal mice were immortalized with Simian virus 40. Two point mutants of the AhR, A375I and A375F, were generated to test the hypothesis that the AhR requires ligand binding to exhibit significant transcriptional activity, both mutants fail to bind ligand or exhibit enhanced activity in cells exposed to AhR ligands. Upon transient, co-expression of ARNT with AhR-A375I or AhR-A375F in AhR-KO cells, these mutants exhibited significant ligand-independent transcriptional activity. However, in CV-1 cells, which others have previously shown to contain relatively high levels of AhR ligand(s), these AhR mutants exhibit essentially no constitutive activity. These results indicate that while the AhR can potentially exhibit activity in the absence of ligand binding, the high constitutive receptor activity observed in many cell lines appears to be due to the presence of endogenous AhR ligands. (c) 2005 Elsevier Inc. All rights reserved.