Mechanism of subtelomeric breaks

描述（由申请人提供）：拷贝数变异（CNV）是基因组多样性和人类疾病的重要来源9,10。亚端粒CNVs是发生在染色体末端的大量缺失、重复和易位，3-6%的特发性智力迟钝病例与此有关6,11-13。亚端粒重排的个体有智力障碍、自闭症、畸形特征和/或其他出生缺陷。儿童通常诊断为亚端粒重排使用细胞遗传学测试，如亚端粒荧光原位杂交（FISH）或阵列比较基因组杂交（CGH）。据估计，亚端粒重排占患病儿童中检测到的致病性CNVs的30%，而亚端粒重排的总体患病率估计为万分之一15。尽管对人类健康有影响，但对染色体断裂和修复引起亚端粒CNV的机制知之甚少。CNV形成的基础生物学研究对于理解致病结构重排的原因和相关危险因素至关重要。我们假设特定的DNA序列容易断裂。为此，我们建议分离亚端粒断裂位点的人类DNA序列，并从功能上剖析导致双链断裂（dsb）的基序。本提案的目的是1)精细绘制亚端粒断点，2)鉴定导致基因组不稳定的亚端粒序列基序，以及3)在酵母总染色体重排（GCR）试验中对断裂基序进行功能性注释，该试验可量化亚端粒序列中的染色体断裂。整合基因组学、生物信息学和体内断裂实验将确定DNA序列是否在亚端粒断裂中起作用。我们的研究还将捕获亚端粒重排的基因组结构，这将使我们能够确定作用于亚端粒dsb的修复机制。这一建议有望揭示促进基因组不稳定性和DNA修复新机制的新序列基序。这些数据对于理解亚端粒重排和整个人类基因组中其他CNV的形成力量至关重要。

DESCRIPTION (provided by applicant): Copy number variation (CNV) is a significant source of genomic diversity and human disease9,10. Subtelomeric CNVs are large deletions, duplications, and translocations that occur at chromosome ends and are responsible for 3-6% of idiopathic mental retardation cases6,11-13. Individuals with subtelomeric rearrangements have intellectual disabilities, autism, dysmorphic features, and/or other birth defects. Children are typically diagnosed with a subtelomeric rearrangement using cytogenetic tests such as subtelomeric fluorescence in situ hybridization (FISH) or array comparative genomic hybridization (CGH). Subtelomeric rearrangements have been estimated to account for up to 30% of pathogenic CNVs detected in affected children9,14, and the overall prevalence of subtelomeric rearrangements is estimated at 1/10,00015. Despite the impact on human health, very little is known about the mechanisms of chromosome breakage and repair that give rise to subtelomeric CNV. Research on the fundamental biology of CNV formation is critical to understanding the causes of and risk factors associated with disease-causing structural rearrangements. We hypothesize that particular DNA sequences are susceptible to breakage. To this end, we propose to isolate human DNA sequences that underlie subtelomeric breakage sites and functionally dissect the motifs that cause double-strand breaks (DSBs). The aims of this proposal are to 1) fine-map subtelomeric breakpoints, 2) identify subtelomeric sequence motifs that contribute to genomic instability, and 3) functionally annotate breakage motifs in a yeast gross chromosomal rearrangement (GCR) assay that quantifies chromosome breakage in the subtelomeric sequence. Integrated genomic, bioinformatics, and in vivo breakage experiments will determine whether or not DNA sequence plays a role in subtelomeric breakage. Our studies will also capture the genomic structure of subtelomeric rearrangements, which will allow us to determine the mechanisms of repair acting on subtelomeric DSBs. This proposal promises to reveal new sequence motifs that promote genomic instability and novel mechanisms of DNA repair. These data will be critical to understanding the forces that shape subtelomeric rearrangements and other CNV throughout the human genome.