Kuhl D, de la Fuente J, Chaturvedi M, Parimoo S, Ryals J, Meyer F, Weissmann C
Cell. 1987 Sep 25;50(7):1057-69. doi: 10.1016/0092-8674(87)90172-3.
The virus-responsive element of the IFN-alpha 1 promoter, VRE(IFN alpha), comprises two imperfect 19 bp repeats, repA and repB. VRE(IFN alpha), tetrameric repA, and tetrameric GAAAGT (a subsequence of repB) or tetrameric AAGTGA conferred inducibility on a reporter gene when placed upstream of a complete or truncated promoter. Induced transcription was weak with a minimal promoter (TATA box only), but was strongly stimulated by the SV40 enhancer placed immediately upstream of the inducible element. Surprisingly, under noninduced conditions, tetrameric repA, GAAAGT, and AAGTGA (but not VRE(IFN alpha)) completely silenced enhancement of constitutive transcription by the SV40 72 bp repeat when interposed between the latter and the TATA box; silencing was fully abrogated by induction.
IFN-α1启动子的病毒反应元件VRE(IFNα)由两个不完全的19bp重复序列repA和repB组成。当置于完整或截短的启动子上游时，VRE(IFNα)、四聚体repA以及四聚体GAAAGT（repB的一个子序列）或四聚体AAGTGA可赋予报告基因诱导性。用最小启动子（仅TATA盒）时诱导转录较弱，但位于诱导元件紧邻上游的SV40增强子可强烈刺激转录。令人惊讶的是，在非诱导条件下，当四聚体repA、GAAAGT和AAGTGA（但不是VRE(IFNα)）插入SV40 72bp重复序列与TATA盒之间时，可完全沉默该重复序列对组成型转录的增强作用；诱导可完全消除这种沉默作用。
