REGULATION OF MOUSE CYP1A1 GENE-EXPRESSION BY DIOXIN - REQUIREMENT OF 2 CIS-ACTING ELEMENTS DURING INDUCTION
REGULATION OF MOUSE CYP1A1 GENE-EXPRESSION BY DIOXIN - REQUIREMENT OF 2 CIS-ACTING ELEMENTS DURING INDUCTION
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DOI：
10.1128/mcb.9.6.2378
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发表时间：
1989-06-01
影响因子：
5.3
通讯作者：
NEBERT, DW
中科院分区：
文献类型：
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作者：
NEUHOLD, LA;SHIRAYOSHI, Y;NEBERT, DW
小鼠细胞色素 P1450 (CYP1A1) 基因负责多种致癌物和有毒化学物质的代谢。环境污染物四氯二苯并二恶英 (TCDD) 的诱导需要功能性芳香烃 (Ah) 受体。我们检查了小鼠肝癌 Hepa-1 野生型细胞和 TCDD 受体复合物染色质结合缺陷的突变株系中 CYP1A1 基因的 5'' 侧翼区域。我们确定了组成型和 TCDD 诱导型 CYP1A1 基因表达所需的两个顺式作用元件（远端，-1071 至 -901 区域；近端，-245 至 -50 区域）。鉴定出与远端元件结合的三类 DNA-蛋白质复合物： I 类，仅在 TCDD 和功能性 Ah 受体存在时发现，其对热不稳定且不与猿猴病毒 40 (SV 40) 早期启动子 DNA 竞争； II类，由至少三个热稳定且与SV40 DNA结合的组成型复合物组成； III类，由至少三个不耐热且不与SV40 DNA竞争的组成型复合物组成。这些蛋白质的基本接触点对于I类复合物集中在-993至-990，对于II类复合物集中在-987、-986或两者，对于III类复合物集中在-938至-927。近端元件对于组成型和 TCDD 诱导型 CYP1A1 基因表达都是绝对必要的，并且至少有两个组成型复合物与该区域结合。这些数据与结合蛋白质的近端元件是必要的但不足以诱导基因表达相一致；发现这些蛋白质与远端元件的相互作用是 TCDD 完全诱导 CYP1A1 所必需的。
The mouse cytochrome P1450 (CYP1A1) gene is responsible for the metabolism of numerous carcinogens and toxic chemicals. Induction by the environmental contaminant tetrachlorodibenzo-p-dioxin (TCDD) requires a functional aromatic hydrocarbon (Ah) receptor. We examined the 5''-flanking region of the CYP1A1 gene in mouse hepatoma Hepa-1 wild-tpe cells and a mutant line having a defect in chromatin binding of the TCDD-receptor complex. We identified two cis-acting elements (distal, -1071 to -901 region; proximal, -245 to -50 region) required for constitutive and TCDD-inducible CYP1A1 gene expression. Three classes of DNA-protein complexes binding to the distal element were identified: class I, found only in the presence of TCDD and a functional Ah receptor, that was heat labile and not competed against by simian virus 40 (SV 40) early promoter DNA; class II, consisting of at least three constitutive complexes that were heat stable and bound to SV40 DNA; and class III, composed of at least three constitutive complexes that were thermolabile and were not competed against by SV40 DNA. Essential contacts for these proteins were centered at -993 to -990 for the class I complex, -987, -986, or both for the class II complexes, and -938 to -927 for the class III complexes. The proximal element was absolutely essential for both constitutive and TCDD-inducible CYP1A1 gene expression, and at least two constitutive complexes bound to this region. These data are consistent with the proximal element that binds proteins being necessary but not sufficient for inducible gene expression; interaction of these proteins with those of the distal element was found to be required for full CYP1A1 induction by TCDD.