Analysis of the "de novo" chromatin opening induced by C/EBPß

C/EBPà 诱导的“从头”染色质打开分析

• 批准号: 5451888
• 负责人: Professor Dr. Karl-Heinz Klempnauer
• 金额: --
• 依托单位: Institut für Biochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5451888?language=en
• 关键词: Analysis; de; novo; chromatin; opening

In eukaryotic cells DNA is associated with histones and exists as a compact structure, the chromatin. The activation of a gene is accompanied by local alterations of the chromatin structure making regulatory regions of the gene accessible for regulatory proteins. The mechanisms of the chromatin-remodeling have been studied in great detail, however, the initial step of opening compacted chromatin structures during the activation of a gene is only poorly understood at present. So-called “pioneer-factors” are assumed to somehow recognize the relevant regions in compact chromatin but how they initiate the opening of the compact chromatin structure has not been studied in much detail because of few of such factors have been identified. The variant histone H3.3 has currently also attracted a lot of attention because it is specifically incorporated into active chromatin regions and appears to play an important role in epigenetic mechanisms, such as epigenetic memory. Our recent work has provided us with an experimental system to study both of these processes, initial chromatin remodelling and H3.3 deposition, and establish the causal relationship between them. Using the chicken mim-1 gene as a model system we have shown that the transcription factor C/EBPβ can act as a pioneer factor and initiate „de novo“ remodelling of silent chromatin at a myeloid-specific enhancer. Furthermore, we have observed that C/EBPβ interacts with the H3.3-specific histone chaperone Hira and induces H3.3 deposition at the mim-1 enhancer, raising the intriguing possibility that both events are linked. In this research project we would like to investigate the novel functions of C/EBPβ in chromatin opening and H3.3 deposition in detail, in order to understand the mechanistic basis and causal relationship of both processes. We expect that this will not only extend our knowledge of the function of C/EBPβ but will also be of general relevance by providing novel insight into the mechanisms that are responsible for initiating chromatin remodelling in silent chromatin and into the role histone H3.3 in this process.

在真核细胞中，DNA与组蛋白结合，并以致密结构染色质的形式存在。基因的激活伴随着染色质结构的局部改变，使得基因的调节区域可被调节蛋白接近。染色质重塑的机制已被详细研究，然而，在基因激活过程中打开紧密染色质结构的初始步骤目前知之甚少。所谓的“先驱因子”被认为以某种方式识别紧密染色质中的相关区域，但是它们如何启动紧密染色质结构的打开还没有被详细研究，因为很少有这样的因子被识别。变异组蛋白H3.3目前也引起了很多关注，因为它被特异性地掺入活性染色质区域，并且似乎在表观遗传机制（如表观遗传记忆）中发挥重要作用。我们最近的工作为我们提供了一个实验系统来研究这两个过程，初始染色质重塑和H3.3沉积，并建立它们之间的因果关系。使用鸡mim-1基因作为模型系统，我们已经表明转录因子C/EBPβ可以作为先锋因子，并在骨髓特异性增强子处启动沉默染色质的“从头”重塑。此外，我们还观察到C/EBPβ与H3.3特异性组蛋白伴侣Hira相互作用，并诱导H3.3沉积在mim-1增强子上，这增加了这两个事件相关的有趣可能性。在本研究项目中，我们希望详细研究C/EBPβ在染色质开放和H3.3沉积中的新功能，以了解这两个过程的机制基础和因果关系。我们希望这不仅将扩展我们对C/EBPβ功能的了解，而且还将通过提供对沉默染色质中启动染色质重塑的机制以及组蛋白H3.3在此过程中的作用的新见解而具有普遍意义。