Eukaryotic Chromosome Replication

描述(申请人提供)：真核细胞的DNA复制是在S阶段，通过在多个复制起点有序地启动复制分叉来完成的。复制缺陷是基因组不稳定的主要来源，导致包括癌症在内的各种人类疾病；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测机制，以监测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损伤和压力时确保忠实基因组维持的机制。在研究酵母中已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tRNAs和转座子)外，还有非常接近断点的复制起源的坊间证据，这将我们引向一条新的询问路线：询问起源是否是基因组中固有的不稳定元素。通过对酿酒酵母与其远亲、基因组复制前的沃尔蒂克鲁维酵母的进化比较，我们发现酿酒酵母的起源确实与基因组重排断裂点高度相关。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，以了解起源的作用和调控的分子机制，特别是起源如何对复制压力和限制复制因素作出反应。7复制起始点的存在和活性与基因组不稳定性之间的直接联系的实验测试。因为基因组重排是癌症进展的一个主要标志，我们认为这些研究路线将阐明起源功能和基因组稳定性之间的相互作用，并在长期内具有开发诊断和治疗策略的潜力。 与公共卫生相关：染色体DNA有序复制的扰动是基因组不稳定的主要来源，导致包括癌症在内的各种人类疾病。与此同时，有证据表明，复制的起源，也就是DNA合成的起始位置，本身就是基因组重排的潜在因素。在这项工作中，我们建议继续研究调控复制有序进行的机制，并开始探索复制起点在导致基因组不稳定中的可能作用。这项工作将扩大我们对基因组疾病潜在机制的理解，阐明健康重要性问题，并有助于我们持续努力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.