Interactions at a dioxin responsive element (DRE) and an overlapping κB site within the hs4 domain of the 3′α immunoglobulin heavy chain enhancer
Interactions at a dioxin responsive element (DRE) and an overlapping κB site within the hs4 domain of the 3′α immunoglobulin heavy chain enhancer
复制标题
DOI：
10.1016/j.tox.2004.03.015
复制
发表时间：
2004-08-05
期刊：
影响因子：
4.5
通讯作者：
Kaminski, NE
中科院分区：
文献类型：
--
作者：
Sulentic, CEW;Kang, JS;Kaminski, NE
我们先前描述的CH 12. LX（AhR表达）和BCL-1（AhR缺陷）B细胞系的结果支持AhR/二恶英反应元件（DRE）介导的TCDD诱导的μ重链表达抑制机制，从而抑制IgM分泌。IG重链基因的转录调控涉及几个调控元件，包括3 'α IG重链增强子，其由跨越约40 kb的四个调控结构域组成。这些结构域之一，hs4，包含一个DRE样的网站，重叠的kappaB基序。我们先前已经证明了TCDD诱导的AhR核复合物和NF-κ B/Rel蛋白分别与DRE和κ B基序的结合，以及TCDD和LPS通过hs4结构域诱导的转录活性。本研究的目的是确定AhR核复合物和NF-κ B/Rel蛋白是否会聚在这两个重叠的顺式元件上并协同作用以影响增强子活性。为了消除与hs4结构域结合的其他转录因子的潜在影响，该方法是构建一系列含有可变重链（V-H）启动子和1.4 kb hs4调节结构域的42 bp片段的荧光素酶报告基因，其仅包括重叠的DRE和kappaB基序或这些基序的突变，用于在CH 12.LX和BCL-1细胞中的瞬时转染实验。在CH12.LX细胞中，TCDD激活了hs4片段;然而，与LPS共处理导致了与野生型1.4 kb hs4结构域相同的显著和协同激活。DRE和kappaB基序中的一个或两个的突变减弱了TCDD和LIPS对具有hs4的42 bp部分的荧光素酶报告子的影响，并且类似于这些处理对单独的启动子的影响。在BCL-1细胞中，hs4片段的活性不被TCDD和/或LPS处理诱导。这些结果表明，AhR核复合物和NF-κ B/Rel蛋白会聚在DRE和κ B基序，以影响hs4增强子片段的转录活性。(C)2004爱思唯尔爱尔兰有限公司保留所有权利。
Our previous results describing the CH12.LX (AhR-expressing) and BCL-1 (AhR-deficient) B cell lines have supported an AhR/dioxin-responsive element (DRE)-mediated mechanism for TCDD-induced inhibition of mu heavy chain expression and thus of IgM secretion. Transcriptional regulation of the Ig heavy chain genes involves several regulatory elements including the 3'alpha Ig heavy chain enhancer, which is composed of four regulatory domains that span approximately 40 kb. One of these domains, hs4, contains a DRE-like site that overlaps a kappaB motif. We have previously demonstrated TCDD-inducible binding of both the AhR nuclear complex and NF-kappaB/Rel proteins to the DRE and kappaB motifs, respectively, as well as TCDD and LPS-induced transcriptional activity through the hs4 domain. The objective of the present study was to determine if the AhR nuclear complex and NF-kappaB/Rel proteins converge at these two overlapping cis-elements and act cooperatively to influence enhancer activity. To eliminate the potential influence of other transcription factors which bind to the hs4 domain, the approach was to construct a series of luciferase reporters containing a variable heavy chain (V-H) promoter and a 42 bp fragment of the 1.4 kb hs4 regulatory domain, that included only the overlapping DRE and kappaB motif or mutations of these motifs for transient transfection experiments in CH12.LX and BCL-1 cells. In the CH12.LX cells, TCDD activated the hs4 fragment; however, co-treatment with LPS led to a marked and synergistic activation as previously observed with the wild type 1.4 kb hs4 domain. Mutation of either or both of the DRE and kappaB motifs diminished the effect of TCDD and LIPS on the luciferase reporters possessing the 42 bp portion of hs4, and resembled the effect of these treatments on the promoter alone. In the BCL-1 cells, activity of the hs4 fragment was not induced by TCDD and/or LPS treatment. These results suggest that the AhR nuclear complex and NF-kappaB/Rel proteins converge at the DRE and kappaB motif to influence transcriptional activity of the hs4 enhancer fragment. (C) 2004 Elsevier Ireland Ltd. All rights reserved.