PDF(Pubmed)
Abstract：
Transcription enhancers are essential activators of V(D)J recombination that orchestrate non-coding transcription through complementary, unrearranged gene segments. How transcription is coordinately increased at spatially distinct promoters, however, remains poorly understood. Using the murine immunoglobulin lambda (Igλ) locus as model, we find that three enhancer-like elements in the 3\' Igλ domain, Eλ3-1, HSCλ1 and HSE-1, show strikingly similar transcription factor binding dynamics and close spatial proximity, suggesting that they form an active enhancer hub. Temporal analyses show coordinate recruitment of complementary V and J gene segments to this hub, with comparable transcription factor binding dynamics to that at enhancers. We find further that E2A, p300, Mediator and Integrator bind to enhancers as early events, whereas YY1 recruitment and eRNA synthesis occur later, corresponding to transcription activation. Remarkably, the interplay between sense and antisense enhancer RNA is central to both active enhancer hub formation and coordinate Igλ transcription: Antisense Eλ3-1 eRNA represses Igλ activation whereas temporal analyses demonstrate that accumulating levels of sense eRNA boost YY1 recruitment to stabilise enhancer hub/promoter interactions and lead to coordinate transcription activation. These studies therefore demonstrate for the first time a critical role for threshold levels of sense versus antisense eRNA in locus activation.
摘要：
转录增强子是V（D）J重组的重要激活子，通过互补，协调非编码转录，未重排的基因片段。转录如何在空间不同的启动子处协调增加，然而,仍然知之甚少。以鼠免疫球蛋白λ（Igλ）基因座为模型，我们发现在3'Igλ域中有三个增强子样元件，Eλ3-1，HSCλ1和HSE-1显示出惊人相似的转录因子结合动力学和紧密的空间接近性，表明它们形成了一个活跃的增强剂中心。时间分析表明，互补的V和J基因片段的协调募集到这个中心，具有与增强子相当的转录因子结合动力学。我们进一步发现E2A，P300，Mediator和Integrator作为早期事件与增强子绑定，而YY1募集和eRNA合成发生较晚，对应于转录激活。值得注意的是,有义和反义增强子RNA之间的相互作用是活性增强子hub形成和协调Igλ转录的中心：反义Eλ3-1eRNA抑制Igλ激活，而时间分析表明，有义eRNA的积累水平促进YY1募集以稳定增强子hub/启动子相互作用并导致协调转录激活。因此，这些研究首次证明了有义与反义eRNA的阈值水平在基因座激活中的关键作用。
