Role of DNA localization in regulating transcription

描述(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，并对转录和染色质结构具有重要但知之甚少的影响。DNA定位到核外周在建立转录抑制中具有明显的作用(Fisher和Merkenschlager，2002)。我对酿酒酵母的研究表明，某些基因在激活时也会被招募到核外围(Brickner和Walter，2004)。我的工作也证实了核周定位促进转录激活(Brickner和Walter，2004)。对酵母的全基因组研究表明，许多转录活性基因定位于核周(Casolari等人，2004年)。小鼠的(3-珠蛋白基因座)转录激活也发生在核周，这表明这一现象在酵母和哺乳动物之间是保守的(Ragoczy等人，2006年)。我的实验室扩大了这些研究的范围，我们发现，向核边缘招募基因是最近转录的一种细胞记忆形式，标记了最近被抑制的基因，以允许更快地重新激活。这个提议的最终目的是理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，以及这种组织是如何影响转录的？我们将重点研究INO1和GAL1基因在酿酒酵母中向核外的动态募集。酵母提供了分子遗传学和生物化学的强大结合，并将为研究这一过程提供一个理想的模型系统。我们将确定基因募集到核外周的功能结果，以及用于影响重定位的分子机制。最后，我们将确定Scs2的生化功能，Scs2是一种核膜蛋白，在核外围的转录激活和抑制中发挥重要作用。这项工作将提供对调节基因表达的机制的第一次理解，这种机制可能在两种人类疾病中存在缺陷。许多急性髓系白血病是由于DMA结合域与核孔蛋白融合所致，推测导致靶基因重新定位到核周并改变基因表达(Lawrence等人，1999；Nakamura等人，1996)。人类Scs2同源基因的突变导致遗传性肌萎缩侧索硬化症(Nishimura等人，2004年)。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.