Chromatin Assembly Structure and Function

描述(申请人提供)：将真核基因组和组蛋白一起包装到染色质中，对DNA模板上发生的所有过程都有深远的影响，包括复制、转录和修复。染色质的组装和拆解是基因组复制所必需的，但人们对此知之甚少。最近的研究(包括我们自己的研究)发现，染色质的组装和拆解与基因组复制无关，是转录调控的新的和重要的手段。该项目的长期目标是对染色质拆解和重组如何调控转录产生统一的理解。我们已经发现了一种新的染色质分解的前体，在体内，在核小体分解之前，转录激活子结合在核小体的二联体对称轴附近。因此，我们的第一个目标是确定染色质的变化，使激活剂足以破坏核小体的稳定，从而驱动染色质的分解。我们的第二个目标是发现启动子染色质分解和重组分别对转录激活和抑制至关重要的基本分子机制。这项拟议的研究还将辨别组蛋白修饰的最终目标是否是调控染色质的拆解和重新组装，并可能识别足以通过复制保持裸露DNA状态的表观遗传标记。我们的第三个目标是描述我们发现的蛋白酶体在染色质分解中的新角色。通过继续使用分子遗传分析，重点放在特征良好的出芽酵母PH05启动子上，结合生物化学和结构方法，我们处于独特的地位，可以填补目前对转录程序的基本调控和遗传的理解中的关键空白。真核生物物种转录调控机制的高度保守性表明，我们的发现将直接适用于人类疾病的分析，包括涉及染色质利用过程缺陷的许多形式的癌症。与公众健康的相关性。许多疾病都是基因表达不正确的结果。这项工作将从机制上理解染色质的组装和拆解，这将进一步促进我们修改人类疾病中涉及的表观遗传密码的能力，以达到治疗干预的目的。

DESCRIPTION (provided by applicant): The packaging of the eukaryotic genome together with histone proteins into chromatin has profound implications for all processes that occur on the DMA template, including replication, transcription and repair. Chromatin assembly and disassembly are essential for duplication of the genome, yet are poorly understood. Recent studies (including our own) have discovered that chromatin assembly and disassembly, independent of genome duplication, are novel and important means of transcriptional regulation. The long-term goal of this project is to generate a unified understanding of how chromatin disassembly and reassembly regulate transcription. We have uncovered a novel precursor of chromatin disassembly where a transcriptional activator is bound near the dyad axis of symmetry of a nucleosome in vivo, prior to nucleosome disassembly. Our first goal therefore is to identify the chromatin changes that enable activators to destabilize a nucleosome enough to drive chromatin disassembly. Our second goal is to discover the fundamental molecular mechanisms whereby promoter chromatin disassembly and reassembly are essential for transcriptional activation and repression, respectively. The proposed research will also discern whether the ultimate target of histone modifications is to regulate chromatin disassembly and reassembly, and may identify the epigenetic mark that is sufficient to maintain a naked DNA state through replication. Our third goal is to characterize the novel role that we have discovered for the proteasome in chromatin disassembly. By continuing to use molecular genetic analyses focusing on the well-characterized budding yeast PH05 promoter coupled with biochemistry and structural approaches, we are uniquely positioned to fill critical gaps in the current understanding of the fundamental regulation and inheritance of transcription programs. The highly conserved nature of transcriptional regulation mechanisms across eukaryotic species indicates that our findings will be directly applicable to the analysis of human diseases, including many forms of cancer that involve defects in chromatin-utilizing processes. Relevance to the public health. Many diseases are the result of incorrect gene expression. The mechanistic understanding of chromatin assembly and disassembly that will come from this work will further our ability to modify the epigenetic codes involved in human diseases for the purpose of therapeutic intervention.