NSF-BSF: Studying the relationship between DNA replication and tandem repeat instability

简单重复DNA序列占人类基因组的3%。个体DNA重复序列的长度可以在世代之间增加，并且这种重复序列的扩增导致超过50种遗传性人类疾病，例如脆性X综合征、弗里德赖希共济失调和亨廷顿病。虽然这些疾病中的每一种都很罕见，但它们总共影响数千名新生儿中的一名，使其成为重大的医疗和社会负担。因此，了解DNA重复序列扩增的基本机制是至关重要的。据信，重复序列在DNA复制过程中偶尔会延长，但对其详细机制知之甚少。美国和以色列的两个研究小组之间的这个合作项目在一个模型实验系统中结合了尖端的遗传学和显微镜研究，以了解重复序列长度在复制过程中如何变化。该项目还为研究生、本科生和高中生创造了跨学科的培训机会。简单DNA重复序列的扩增是人类许多遗传性疾病的标志。Mirkin（塔夫茨大学）和Aharoni（内盖夫本-古里安大学）实验室之间的这个合作项目旨在了解复制体完整性如何确保简单DNA重复序列的正确复制并抵消其不稳定性。利用S.酿酒酵母作为模式生物，该项目结合了测量各种DNA重复序列不稳定性的遗传测定（例如，扩增、收缩和脆性），通过这些序列进行复制体进展的单细胞活显微镜分析。这种双重方法将有可能解决重复序列的长度，其形成动态DNA结构的倾向，以及其相对于复制方向的方向如何影响分叉的进展。该项目特别强调的是在重复不稳定性中前导链和滞后链合成之间的耦合以及dNTP池复杂性的作用。这一美国/以色列合作项目得到了美国国家科学基金会和以色列两国科学基金会的支持。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Simple repetitive DNA sequences account for 3% of human genome. The length of individual DNA repeats can increase between generations, and this repeat expansion leads to over 50 hereditary human diseases, such as fragile X syndrome, Friedreich’s ataxia and Huntington’s disease. While each of these diseases is rare, altogether they affect one in several thousand newborns, making them a significant medical and societal burden. Thus, understanding the fundamental mechanisms of DNA repeat expansions is of prime importance. It is believed that repeats can occasionally lengthen during DNA replication, but the detailed mechanisms are poorly understood. This collaborative project between two research groups in the US and Israel combines cutting edge genetic and microscopy studies in a model experimental system to understand how repeat length changes during their replication. The project also creates cross-disciplinary training opportunities for graduate, undergraduate and high school students.Expansion of simple DNA repeats is a hallmark of numerous hereditary diseases in humans. This collaborative project between the Mirkin (Tufts University) and Aharoni (Ben-Gurion University of the Negev) laboratories aims to understand how replisome integrity ensures proper replication of simple DNA repeats and counteracts their instability. Using S. cerevisiae as a model organism, the project combines genetic assays that measure instability of various DNA repeats (e.g., expansions, contractions, and fragility), with single-cell live-microscopy analysis of replisome progression through these sequences. This dual approach will make it possible to resolve how a repeat’s length, its propensity to form dynamic DNA structures, and its orientation relative to the direction of replication affect progression of the fork. A particular emphasis of the project is on the role of coupling between leading and lagging strand syntheses and dNTP pool complexity in repeat instability.This collaborative US/Israel project is supported by the US National Science Foundation and the Israeli Binational Science Foundation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.