An HMG I/Y-containing repressor complex and supercoiled DNA topology are critical for long-range enhancer-dependent transcription in vitro.
An HMG I/Y-containing repressor complex and supercoiled DNA topology are critical for long-range enhancer-dependent transcription in vitro.
复制标题
含有 HMG I/Y 的阻遏物复合物和超螺旋 DNA 拓扑对于体外长程增强子依赖性转录至关重要。
DOI：
10.1101/gad.11.5.629
复制
发表时间：
1997
影响因子：
10.5
通讯作者：
Emerson,BM
中科院分区：
文献类型：
--
作者：
Bagga,R;Emerson,BM
T 细胞受体 α 链 (TCR α) 基因的 3' 增强子指导该基因位点的组织和阶段特异性表达以及 V(D)J 重组。使用有效复制 TCR α 增强子活性的体外系统，我们发现长程启动子-增强子调节需要 T 细胞特异性阻遏物复合物，并且对 DNA 拓扑结构敏感。在该系统中，增强子的作用是去抑制超螺旋模板上的启动子，但不是松弛的模板。我们发现 TCR α 启动子被包含结构蛋白 HMG I/Y 的阻遏复合物失活。在缺乏该阻遏复合物的情况下，TCR α 基因的表达完全独立于 3' 增强子和 DNA 拓扑。 T 细胞限制蛋白 LEF-1 与 TCR α 增强子的相互作用是启动子去抑制所必需的。在该系统中，TCR α 增强子增加活性启动子的数量而不是转录速率。因此，长程增强子以与启动子不同的方式发挥作用，并提供阻遏子、DNA 拓扑和基因活性之间的调节联系。
The 3' enhancer of the T cell receptor alpha-chain (TCR alpha) gene directs the tissue- and stage-specific expression and V(D)J recombination of this gene locus. Using an in vitro system that reproduces TCR alpha enhancer activity efficiently, we show that long-range promoter-enhancer regulation requires a T cell-specific repressor complex and is sensitive to DNA topology. In this system, the enhancer functions to derepress the promoter on supercoiled, but not relaxed, templates. We find that the TCR alpha promoter is inactivated by a repressor complex that contains the architectural protein HMG I/Y. In the absence of this repressor complex, expression of the TCR alpha gene is completely independent of the 3' enhancer and DNA topology. The interaction of the T cell-restricted protein LEF-1 with the TCR alpha enhancer is required for promoter derepression. In this system, the TCR alpha enhancer increases the number of active promoters rather than the rate of transcription. Thus, long-range enhancers function in a distinct manner from promoters and provide the regulatory link between repressors, DNA topology, and gene activity.