Department of Human Genetics, Laboratory of Developmental Biology, Royal Victoria Hospital, H-5, McGill University Health Centre, Montreal, Quebec, Canada.
Nucleic Acids Res. 2011 Apr;39(7):2548-58. doi: 10.1093/nar/gkq1160. Epub 2010 Dec 3.
Multiple regulatory modules contribute to the complex expression programs realized by many loci. Although long thought of as isolated components, recent studies demonstrate that such regulatory sequences can physically associate with promoters and with each other and may localize to specific sub-nuclear transcription factories. These associations provide a substrate for putative interactions and have led to the suggested existence of a transcriptional interactome. Here, using a controlled strategy of transgenesis, we analyzed the functional consequences of regulatory sequence interaction within the myelin basic protein (mbp) locus. Interactions were revealed through comparisons of the qualitative and quantitative expression programs conferred by an allelic series of 11 different enhancer/inter-enhancer combinations ligated to a common promoter/reporter gene. In a developmentally contextual manner, the regulatory output of all modules changed markedly in the presence of other sequences. Predicted by transgene expression programs, deletion of one such module from the endogenous locus reduced oligodendrocyte expression levels but unexpectedly, also attenuated expression of the overlapping golli transcriptional unit. These observations support a regulatory architecture that extends beyond a combinatorial model to include frequent interactions capable of significantly modulating the functions conferred through regulatory modules in isolation.
多个调控模块有助于许多基因座实现复杂的表达程序。尽管这些调控序列长期以来被认为是相互隔离的元件，但最近的研究表明，它们可以与启动子和彼此发生物理关联，并可能定位于特定的核转录工厂。这些关联为潜在的相互作用提供了基础，并导致了转录组相互作用体的提出。在这里，我们使用转基因的受控策略，分析了髓鞘碱性蛋白 (mbp) 基因座内调控序列相互作用的功能后果。通过比较连接到共同启动子/报告基因的 11 种不同增强子/增强子组合的等位基因系列赋予的定性和定量表达程序，揭示了相互作用。以发育上下文的方式，所有模块的调控输出在存在其他序列的情况下都发生了显著变化。根据转基因表达程序预测，从内源性基因座中删除一个这样的模块会降低少突胶质细胞的表达水平，但出人意料的是，也会减弱重叠的 golli 转录单元的表达。这些观察结果支持一种调控架构，该架构超越了组合模型，包括频繁的相互作用，这些相互作用能够显著调节通过单独的调控模块赋予的功能。
