Eukaryotic Chromosome Replication

描述（由申请人提供）：真核DNA复制是通过在S期以有序序列在多个复制起点启动复制叉来完成的。复制缺陷是导致包括癌症在内的多种人类疾病的基因组不稳定性的主要来源;在酿酒酵母中，扰乱基因组的有序复制导致基因组不稳定。细胞已经进化出复杂的监视机制来监控其基因组的完整性和有序复制。因此，为了充分了解基因组不稳定性疾病的原因和机制，我们必须了解设计复制程序的分子机制以及在面对DNA损伤和压力时确保基因组忠实维持的机制。在研究酵母中报道的一些染色体重排时，我们注意到除了已知的重复元件（如tRNA和转座子）之外，还有轶事证据表明复制起点非常接近断点，这使我们进入了一个新的研究方向：询问起点是否是基因组中固有的不稳定因素。利用S.酿酒酵母与其远缘的、前基因组复制的相对的克鲁维酵母Waltii，我们已经发现起源于S.酿酒酵母与基因组重排断裂点确实高度相关。因此，这项建议有两个广泛的主题：7继续我们正在进行的努力，以了解原产地的行动和监管的分子机制，特别是重点对原产地如何应对复制压力和限制复制因子。7复制起点的存在和活动与基因组不稳定性之间的直接联系的实验测试。由于基因组重排是癌症进展的主要标志，我们认为这些研究将阐明起源功能和基因组稳定性之间的相互作用，并在长期内有可能开发诊断和治疗策略。 公共卫生相关性：染色体DNA有序复制的扰动是导致包括癌症在内的多种人类疾病的基因组不稳定性的主要来源。与此同时，有证据表明，复制起点，即DNA合成起始的位点，本身就是基因组重排的潜在因素。在这项工作中，我们建议继续我们的调查机制，调节复制的有序进行，并开始探索可能的作用，导致基因组不稳定的复制起点。这项工作将扩大我们对基因组疾病的机制的理解，阐明健康重要性的问题，并有助于我们正在进行的努力，以了解基因组结构和复制之间的相互作用。

DESCRIPTION (provided by applicant): Eukaryotic DNA replication is accomplished by initiating replication forks at multiple origins of replication in an ordered sequence during S phase. Replication defects are a major source of genomic instability leading to a variety of human disorders including cancer; in the yeast Saccharomyces cerevisiae, perturbing the orderly replication of the genome leads to genome instability. Cells have evolved elaborate surveillance mechanisms to monitor the integrity and orderly duplication of their genomes. To fully understand the causes and mechanisms of genome-instability disorders, therefore, it is crucial that we understand the molecular mechanisms choreographing the replication program and the mechanisms that ensure faithful genome maintenance in the face of DNA damage and stress. In examining some chromosomal rearrangements that have been reported in yeast, we note that in addition to the known repeated elements (such as tRNAs and transposons), there is anecdotal evidence for origins of replication very close to the breakpoint, leading us a to a new line of enquiry: to ask whether origins are intrinsically destabilizing elements in the genome. Drawing on evolutionary comparisons of S. cerevisiae with its distant, pre-genome- duplication relative Kluyveromyces waltii, we have found that origins in S. cerevisiae are indeed very highly correlated with genome rearrangement breakpoints. This proposal therefore has two broad themes: 7 A continuation of our ongoing efforts to understand the molecular mechanisms of origin action and regulation, with particular focus on how origins respond to replication stress and limiting replication factors. 7 Experimental tests for a direct link between the presence and activity of replication origins and genome instability. Because genome rearrangements are a major hallmark of cancer progression, we feel that these lines of enquiry will elucidate the interplay between origin function and genome stability, and in the long term have potential for developing both diagnostic and treatment strategies. PUBLIC HEALTH RELEVANCE: Perturbations in the orderly duplication of chromosomal DNA are a major source of genomic instability leading to a variety of human disorders including cancer. At the same time, there is evidence that origins of replication, the sites where DNA synthesis is initiated, are themselves potential agents of genome rearrangements. In this work, we propose to continue our investigations into the mechanisms that modulate the orderly progression of replication, and begin exploring the possible role of replication origins in leading to genome instability. This work will expand our understanding of the mechanisms underlying genome disorders, shed light on questions of health importance, and contribute to our ongoing efforts to understand the interplay between genome structure and replication.