Modeling chromosome structure instability in the mouse

小鼠染色体结构不稳定性建模

• 批准号: 8757755
• 负责人: MATHEW J THAYER
• 金额: $ 20.1万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8757755
• 关键词: Adult; Affect; Alleles; Biological Assay; Biological Models; Biology; Cell Cycle; Centromere; Characteristics; Chromatin Structure; Chromosomal Instability; Chromosome Condensation; Chromosome Structures; Chromosomes; Chromosomes, Human, Pair 15; Chromosomes, Human, Pair 3; Chromosomes, Human, Pair 4; Chromosomes, Human, Pair 6; Chromosomes, Human, Pair 7; Cis-Acting Sequence; Collaborations; DNA Sequence Rearrangement; Elements; Engineering; Ensure; Exhibits; Foundations; Functional RNA; Gene Expression; Genes; Genetic Transcription; Genome; Genomic Instability; Heart; Human; Human Chromosomes; Human Development; In Vitro; Indium; Individual; Knock-out; Lead; Malignant Neoplasms; Mammalian Chromosomes; Mitotic; Mitotic Chromosome; Modeling; Molecular; Mono-S; Mus; Mutation; Names; Pathogenesis; Phenocopy; Phenotype; Physical condensation; Property; RNA; Replication Origin; Somatic Cell; Stem cells; Structure; Testing; Time; Transgenes; Tumor Suppressor Proteins; Tumor-Derived; Work; X Chromosome; autosome; cancer cell; cis acting element; design; embryonic stem cell; in vivo; insight; mammalian genome; mouse model; neoplastic cell; novel; novel therapeutic intervention; public health relevance; research study; segregation; telomere; tumor; tumorigenesis

DESCRIPTION (provided by applicant): Cancer cells differ from their normal cellular counterparts in many important characteristics. These 'hallmarks' of cancer are acquired during the multistep development of human cancer. Not surprisingly, genetic alterations are present in most, if not all cancers, and are thought to lie at the heart of these phenotypic alterations. In addition, genomic instability, defined as an increase in the rate at which spontaneous mutations occur, is considered to be one of the hallmarks of cancer and is thought to be required to generate the numerous genetic changes that are present in individual tumor cells. Previous studies from my lab indicate that certain tumor-derived chromosome rearrangements exhibit a chromosome wide delay in replication timing (DRT) and a subsequent delay in mitotic chromosome condensation (DMC). In addition, we found that DRT/DMC causes an ~50 fold increase in the rate at which secondary rearrangements occur on the affected chromosome, providing formal proof that DRT/DMC causes genomic instability. In our most recent studies, we have used chromosome-engineering strategies to identify an autosomal locus that when disrupted results in DRT/DMC. These studies led to the identification of a discrete cis-acting locus that controls replication timing, mitotic condensation and structural stability of human chromosome 6. Moreover, molecular characterization of this locus identified a large non-coding RNA gene, which we named Asynchronous replication and Autosomal RNA on chromosome 6 (ASAR6). As the name implies, ASAR6 displays asynchronous replication timing between alleles. In addition, ASAR6 displays random monoallelic expression, and disruption of the expressed allele results in DRT/DMC and structural instability of human chromosome 6. Importantly, recent work from the Y. Marahrens' indicated that deletion of the Xist gene, in adult somatic cells, results in delayed replication, abnormal chromatin structure and instability of the chromosome. Therefore, disruption of ASAR6 results in an apparent phenocopy of deletion of Xist. Because we have detected DRT/DMC on numerous human and mouse chromosomes, our observations have led to the novel hypothesis that 'inactivation/stability centers' are present on all mammalian chromosomes. We believe that these observations represent the discovery of a new fundamental property of all mammalian chromosomes. Thus, we are proposing that every mammalian chromosome contains four cis-acting elements that ensure proper replication, segregation and stability: 1) centromeres, 2) telomeres, 3) origins of replication, and 4) inactivation/stability centers. This proposal represents collaboration between the Thayer and Grompe labs, and is designed to characterize the ASAR6-syntenic locus in the mouse. In addition, this proposal is designed to determine if the structural instability of individual chromosomes caused by disruption of an autosomal inactivation/stability center results in an increase in tumor formation using conditional knockout strategies in the mouse.

描述（由申请人提供）：癌细胞在许多重要特征上不同于其正常细胞对应物。这些癌症的“标志”是在人类癌症的多步发展过程中获得的。毫不奇怪，遗传改变存在于大多数（如果不是所有）癌症中，并且被认为是这些表型改变的核心。此外，基因组不稳定性（定义为自发突变发生率的增加）被认为是癌症的标志之一，并且被认为是产生个体肿瘤细胞中存在的众多遗传变化所必需的。我实验室以前的研究表明，某些肿瘤来源的染色体重排表现出复制时间（DRT）的染色体范围延迟和随后的有丝分裂染色体浓缩（DMC）延迟。此外，我们发现DRT/DMC导致受影响染色体上发生二级重排的速率增加约50倍，这为DRT/DMC导致基因组不稳定性提供了正式证据。在我们最近的研究中，我们已经使用染色体工程策略来确定一个常染色体位点，当被破坏时会导致DRT/DMC。这些研究导致了一个离散的顺式作用基因座，控制复制时间，有丝分裂凝聚和人类6号染色体的结构稳定性的鉴定。此外，该位点的分子特征鉴定了一个大的非编码RNA基因，我们将其命名为6号染色体上的异步复制和常染色体RNA（ASAR 6）。顾名思义，ASAR 6在等位基因之间显示异步复制时间。此外，ASAR 6显示随机单等位基因表达，并且表达的等位基因的破坏导致DRT/DMC和人6号染色体的结构不稳定性。重要的是，Y. Marahrens的研究表明，在成体细胞中，Xist基因的缺失导致复制延迟、染色质结构异常和染色体不稳定。因此，ASAR 6的破坏导致Xist缺失的明显表型。因为我们已经在许多人类和小鼠染色体上检测到DRT/DMC，我们的观察导致了“失活/稳定中心”存在于所有哺乳动物染色体上的新假设。我们相信，这些观察结果代表了所有哺乳动物染色体的一个新的基本性质的发现。因此，我们提出每个哺乳动物染色体都含有四个顺式作用元件，以确保正确的复制，分离和稳定性：1）着丝粒，2）端粒，3）复制起点，和4）失活/稳定中心。该提案代表了Thayer和Grompe实验室之间的合作，旨在表征小鼠中的ASAR 6-同线基因座。此外，该提议旨在确定是否由常染色体失活/稳定性中心的破坏引起的单个染色体的结构不稳定性导致在小鼠中使用条件性敲除策略的肿瘤形成增加。