Role of DNA localization in regulating transcription

描述（由申请人提供）：DNA的亚核定位在所有真核生物中都受到高度调控，并且对转录和染色质结构具有重要但鲜为人知的影响。DNA在细胞核边缘的定位在转录抑制的建立中具有明确的作用（Fisher和Merkenschlager， 2002）。我对酿酒酵母的研究表明，某些基因在激活后也被招募到核周围（Brickner和Walter， 2004）。我的工作还证实，核外围的定位促进转录激活（Brickner和Walter， 2004）。酵母全基因组研究表明，许多转录活性基因位于细胞核外围（Casolari et al., 2004）。小鼠3-珠蛋白位点的转录激活也发生在核外周，这表明这种现象在酵母和哺乳动物之间是保守的（Ragoczy et al., 2006）。我的实验室已经扩展了这些研究，我们发现基因募集到核周围是最近转录的细胞记忆的一种形式，标记最近被抑制的基因，以允许更快的重新激活。这项提议的最终目的是了解细胞生物学中的两个基本问题：细胞核是如何在空间上组织的，以及这种组织如何影响转录？我们将重点研究INO1和GAL1基因在酿酒酵母核外周的动态募集。酵母提供了分子遗传学和生物化学的强大结合，将为研究这一过程提供理想的模型系统。我们将定义基因募集到核外周的功能结果和用于影响再定位的分子机制。最后，我们将定义Scs2的生化功能，Scs2是一种核包膜蛋白，在核外周的转录激活和抑制中发挥重要作用。这项工作将首次提供对两种人类疾病中可能存在缺陷的基因表达调节机制的理解。许多急性髓性白血病是由DMA结合域与核孔蛋白融合引起的，可能导致靶基因重新定位到核外周并改变基因表达（Lawrence等人，1999；Nakamura等人，1996）。人类Scs2同源基因突变可导致遗传性肌萎缩性侧索硬化症（Nishimura et al., 2004）。了解DMA定位在控制基因表达中的作用可能有助于阐明这些疾病的细胞和分子缺陷。

DESCRIPTION (provided by applicant): The sub-nuclear localization of DNA is highly regulated in all eukaryotes and has important but poorly understood effects on transcription and chromatin structure. The localization of DNA to the nuclear periphery has a clear role in establishing transcriptional repression (Fisher and Merkenschlager, 2002). My studies in Saccharomyces cerevisiae revealed that certain genes are also recruited to the nuclear periphery upon activation (Brickner and Walter, 2004). My work also established that localization to the nuclear periphery promotes transcriptional activation (Brickner and Walter, 2004). Genome-wide studies in yeast indicate that many transcriptionally active genes localize at the nuclear periphery (Casolari et al., 2004). Transcriptional activation of the (3-globin locus in mice also occurs at the nuclear periphery, suggesting that this phenomenon is conserved between yeast and mammals (Ragoczy et al., 2006). My lab has extended these studies and we have discovered that gene recruitment to the nuclear periphery serves as a form of cellular memory of recent transcription, marking recently repressed genes to allow more rapid reactivation. The ultimate objective of this proposal is to understand two fundamental questions in cell biology: how is the nucleus spatially organized and how does this organization affect transcription? We will focus on the dynamic recruitment of the INO1 and GAL1 genes to the nuclear periphery in Saccharomyces cerevisiae. Yeast offers a powerful combination of molecular genetics and biochemistry and will provide an ideal model system for studying this process. We will define the functional outcome of gene recruitment to the nuclear periphery and the molecular mechanisms used to affect relocalization. Finally, we will define the biochemical function of Scs2, a nuclear envelope membrane protein that plays important roles in both transcriptional activation and repression at the nuclear periphery. This work will provide the first understanding of a mechanism of regulating gene expression that may be defective in two human diseases. A number of acute myeloid leukemias result from fusion of DMA binding domains with nuclear pore proteins, presumably leading to relocalization of target genes to the nuclear periphery and alterations in gene expression (Lawrence et al., 1999; Nakamura et al., 1996). Mutations in the human homologue of Scs2 result in an inherited form of amyotrophic lateral sclerosis (Nishimura et al., 2004). Understanding the role of DMA localization in controlling gene expression may illuminate the cellular and molecular defects in these diseases.