Differences in transactivation between rat CYP3A1 and human CYP3A4 genes by human pregnane X receptor.
Differences in transactivation between rat CYP3A1 and human CYP3A4 genes by human pregnane X receptor.
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DOI：
10.2133/dmpk.19.103
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发表时间：
2004-04-01
影响因子：
2.1
通讯作者：
Yamazoe, Yasushi
中科院分区：
文献类型：
--
作者：
Takada, Tomonari;Ogino, Makoto;Yamazoe, Yasushi
在使用用启动子构建的人CYP 3A 4报告基因的测定系统中，（+11 nt至-362 nt）和增强子（-7.2knt至-7.8knt）区域，包括由六个核苷酸分隔的翻转重复（ER-6）和由三个核苷酸分隔的直接重复（DR-3）基序，在利福平处理的HepG 2细胞中检测到CYP 3A 4反式激活，而没有任何核受体的过表达。过表达人PXR增强了反式激活。大鼠CYP 3A 1报告基因构建的启动子区（+31 nt至-171 nt），包括DR-3和ER-6基序，然而，没有反式激活利福平处理的细胞，即使在过表达hPXR。尽管类维生素A X受体α（RXR α）的过表达对两种CYP 3A报告基因均无明显影响，但载脂蛋白AI调节蛋白-1（阿普-1）与hPXR的共表达导致了利福平诱导的CYP 3A 1报告基因的反式激活。保留两个基序的截短CYP 3A 4报告基因显示利福平诱导的hPXR和阿普-1过表达的反式激活，而在hPXR过表达的细胞中未观察到反式激活。这些结果支持这样的想法，即RXR α以外的核受体可能在CYP 3A反式激活中与hPXR一起发挥作用。本研究还表明，一个新的顺式元件参与hPXR介导的CYP 3A 4反式激活。
In an assay system using a human CYP3A4 reporter constructed with the promoter (+11 nt to -362 nt) and enhancer (-7.2 knt to -7.8 knt) regions including everted repeat separated by six nucleotides (ER-6) and direct repeat separated by three nucleotides (DR-3) motifs, the CYP3A4 transactivation was detected without overexpression of any nuclear receptors in rifampicin-treated HepG2 cells. Overexpression of human pregnane X receptor (hPXR) enhanced the transactivation. Rat CYP3A1 reporter constructed with the promoter region (+31 nt to -171 nt) including both DR-3 and ER-6 motifs was, however, not transactivated in rifampicin-treated cells, even after overexpression of hPXR. Although overexpression of retinoid X receptor alpha (RXRalpha) had no clear effect for both CYP3A reporters, co-expression of apolipoprotein AI regulatory protein-1 (ARP-1) with hPXR resulted in the rifampicin-induced transactivation of the CYP3A1 reporter. A truncated CYP3A4 reporter retaining the both motifs showed the rifampicin-induced transactivation by overexpression of hPXR and ARP-1, while the transactivation in hPXR-overexpressed cells was not observed. These results support the idea that a nuclear receptor other than RXRalpha may play a role in the CYP3A transactivation together with hPXR. The present study also suggests the involvement of a novel cis-element in the hPXR-mediated CYP3A4 transactivation.