Post-transcriptional regulation of human pregnane x receptor by micro-RNA affects the expression of cytochrome P450 3A4
Post-transcriptional regulation of human pregnane x receptor by micro-RNA affects the expression of cytochrome P450 3A4
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DOI：
10.1074/jbc.m709382200
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发表时间：
2008-04-11
影响因子：
4.8
通讯作者：
Yokoi, Tsuyoshi
中科院分区：
文献类型：
--
作者：
Takagi, Shingo;Nakajima, Miki;Yokoi, Tsuyoshi
妊娠素X受体（Pregnane X receptor， PXR）是调节多种转运蛋白和药物代谢酶诱导表达的主要转录因子，包括CYP3A4 （cytochrome P450 3A4）。我们首先在25个人类肝脏中发现PXR mRNA水平与PXR蛋白水平不相关，这表明参与了转录后调控。值得注意的是，在人类PXR mRNA的3'-非翻译区发现了一个潜在的miR-148a识别元件。我们研究了PXR是否可能受到miR-148a的调控。报告细胞实验显示miR-148a可以识别PXR mRNA的miR-148a识别元件。过表达miR-148a可使PXR蛋白水平降低，抑制miR-148a可使PXR蛋白水平升高。mir -148a依赖性PXR蛋白的降低减弱了CYP3A4 mRNA的诱导作用。此外，PXR的翻译效率（PXR蛋白/PXR mRNA比值）与miR-148a在25个人类肝脏中的表达水平呈负相关，支持miR-148a依赖于人类肝脏中PXR的调控。最终，PXR蛋白水平与CYP3A4 mRNA和蛋白水平显著相关。总之，我们发现miR-148a转录后调控人PXR，导致人肝脏中CYP3A4诱导和/或构成水平的调节。这项研究将为尚未解决的CYP3A4表达的大个体间差异的机制提供新的见解。
Pregnane X receptor (PXR) is a major transcription factor regulating the inducible expression of a variety of transporters and drug-metabolizing enzymes, including CYP3A4 (cytochrome P450 3A4). We first found that the PXR mRNA level was not correlated with the PXR protein level in a panel of 25 human livers, indicating the involvement of post-transcriptional regulation. Notably, a potential miR-148a recognition element was identified in the 3'-untranslated region of human PXR mRNA. We investigated whether PXR might be regulated by miR-148a. A reporter assay revealed that miR-148a could recognize the miR-148a recognition element of PXR mRNA. The PXR protein level was decreased by the overexpression of miR-148a, whereas it was increased by inhibition of miR-148a. The miR-148a-dependent decrease of PXR protein attenuated the induction CYP3A4 mRNA. Furthermore, the translational efficiency of PXR (PXR protein/PXR mRNA ratio) was inversely correlated with the expression levels of miR-148a in a panel of 25 human livers, supporting the miR-148a-dependent regulation of PXR in human livers. Eventually, the PXR protein level was significantly correlated with the CYP3A4 mRNA and protein levels. In conclusion, we found that miR-148a post-transcriptionally regulated human PXR, resulting in the modulation of the inducible and/or constitutive levels of CYP3A4 in human liver. This study will provide new insight into the unsolved mechanism of the large interindividual variability of CYP3A4 expression.