Identification of Amino Acid Residues in the Ligand-Binding Domain of the Aryl Hydrocarbon Receptor Causing the Species-Specific Response to Omeprazole: Possible Determinants for Binding Putative Endogenous Ligands
Identification of Amino Acid Residues in the Ligand-Binding Domain of the Aryl Hydrocarbon Receptor Causing the Species-Specific Response to Omeprazole: Possible Determinants for Binding Putative Endogenous Ligands
复制标题
芳基烃受体配体结合域中引起奥美拉唑物种特异性反应的氨基酸残基的鉴定：结合假定内源配体的可能决定因素
DOI：
10.1124/mol.113.088856
复制
发表时间：
2014
影响因子：
3.6
通讯作者：
T. Yagi
中科院分区：
文献类型：
--
作者：
K. Shiizaki;S. Ohsako;M. Kawanishi;T. Yagi
奥美拉唑（OME）通过体内和体外激活芳香烃受体（AhR）诱导编码药物代谢酶（如CYP1A1）的基因表达。然而，OME介导的AhR激活的确切机制仍在研究中。在阐明物种特异性对二恶英的敏感性的同时，我们发现OME介导的AhR激活是哺乳动物物种特异性的。此外，我们以前报道过OME对CYP1A1酶具有抑制活性。根据这些观察结果，我们推测OME介导的AhR靶基因转录是由于通过抑制CYP1A1活性增加血清中推定AhR配体的量而激活AhR。我们比较了OME敏感的兔AhR和不敏感的小鼠AhR的氨基酸序列，以确定负责物种特异性反应的残基。通过在小鼠和兔AhR之间交换结构域来构建嵌合AhR，以限定对OME的应答所需的区域。OME介导的反式激活仅在嵌合AhR中观察到，该嵌合AhR包括兔AhR的配体结合结构域（LBD）。定点突变揭示了三个氨基酸（M328，T353，和F367）在兔AhR负责OME介导的反式激活。用小鼠AhR的那些残基替换这些残基消除了兔AhR的响应。与此相反，这些氨基酸的取代与那些兔AhR改变不敏感的小鼠AhR成为敏感的OME。这些结果表明，OME介导的AhR激活需要LBD内的特定结构，这可能是必不可少的结合与神秘的内源性配体。
Omeprazole (OME) induces the expression of genes encoding drug-metabolizing enzymes, such as CYP1A1, via activation of the aryl hydrocarbon receptor (AhR) both in vivo and in vitro. However, the precise mechanism of OME-mediated AhR activation is still under investigation. While elucidating species-specific susceptibility to dioxin, we found that OME-mediated AhR activation was mammalian species specific. Moreover, we previously reported that OME has inhibitory activity toward CYP1A1 enzymes. From these observations, we speculated that OME-mediated AhR target gene transcription is due to AhR activation by increasing amounts of putative AhR ligands in serum by inhibition of CYP1A1 activity. We compared the amino acid sequences of OME-sensitive rabbit AhR and nonsensitive mouse AhR to identify the residues responsible for the species-specific response. Chimeric AhRs were constructed by exchanging domains between mouse and rabbit AhRs to define the region required for the response to OME. OME-mediated transactivation was observed only with the chimeric AhR that included the ligand-binding domain (LBD) of the rabbit AhR. Site-directed mutagenesis revealed three amino acids (M328, T353, and F367) in the rabbit AhR that were responsible for OME-mediated transactivation. Replacing these residues with those of the mouse AhR abolished the response of the rabbit AhR. In contrast, substitutions of these amino acids with those of the rabbit AhR altered nonsensitive mouse AhR to become sensitive to OME. These results suggest that OME-mediated AhR activation requires a specific structure within LBD that is probably essential for binding with enigmatic endogenous ligands.
登录
查看更多内容
DOI：
--
发表时间：
1989-10
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
M. Denison;J. Fisher;J. Whitlock
通讯作者：
M. Denison;J. Fisher;J. Whitlock
DOI：
10.1073/pnas.89.17.8185
发表时间：
1992-09-01
影响因子：
11.1
作者：
BURBACH, KM;POLAND, A;BRADFIELD, CA
通讯作者：
BRADFIELD, CA
影响因子：
3.8
作者：
DiNatale, Brett C.;Murray, Iain A.;Perdew, Gary H.
通讯作者：
Perdew, Gary H.
影响因子：
3.9
作者：
Murray, IA;Reen, RK;Perdew, GH
通讯作者：
Perdew, GH