Chromatin Assembly Structure and Function

描述（由申请人提供）：真核基因组与组蛋白一起包装到染色质中对DMA模板上发生的所有过程（包括复制、转录和修复）具有深远意义。染色质的组装和拆卸是基因组复制所必需的，但了解甚少。最近的研究（包括我们自己的）发现，染色质组装和拆卸，独立于基因组复制，是新的和重要的转录调控手段。该项目的长期目标是对染色质的拆卸和重组如何调节转录产生统一的理解。我们已经发现了一种新的前体染色质拆卸转录激活剂结合在附近的二分体对称轴的核小体在体内，核小体拆卸之前。因此，我们的第一个目标是确定染色质的变化，使激活剂不稳定的核小体足以驱动染色质解体。我们的第二个目标是发现基本的分子机制，启动子染色质拆卸和重组是必不可少的转录激活和抑制，分别。拟议的研究还将辨别组蛋白修饰的最终目标是否是调节染色质的分解和重组，并可能确定足以通过复制维持裸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作用。通过继续使用分子遗传学分析，重点是充分表征的芽殖酵母PH05启动子，再加上生物化学和结构方法，我们处于独特的地位，以填补关键的空白，在目前的理解的基本调控和遗传的转录程序。跨真核物种的转录调控机制的高度保守性表明，我们的研究结果将直接适用于人类疾病的分析，包括许多形式的癌症，涉及在染色质利用过程中的缺陷。与公众健康的相关性。许多疾病是基因表达不正确的结果。从这项工作中对染色质组装和拆卸的机械理解将进一步提高我们修改人类疾病所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.