Effect of Spatial Proximity on Chromosomal Translocations

描述（由申请人提供）：空间邻近性对染色体易位的影响染色体易位是一种已知参与癌症发展和进展的基因组重排类型，它们涉及两个非同源染色体之间的遗传物质交换。在某些癌症中，特别是白血病，淋巴瘤和肉瘤，特定的易位是复发性的，这意味着不同的患者存在涉及相同两条染色体上相同两个位点的易位。某些易位的重复出现导致了这样的假设，即基因组的某些区域更容易重排，可能是通过核空间中的紧密空间接近。尽管使用例如荧光原位杂交（FISH）技术的相关证据表明基因组的通常易位区域的紧密空间接近，但是空间接近有助于染色体易位的形成的想法尚未被直接或彻底地测试。我们的实验室开发了一种新的遗传系统，我们可以检测非同源末端连接（NHEJ）介导的相互染色体易位在S。酿酒模式生物该系统允许同时诱导不同染色体上的DNA双链断裂，以及相互染色体易位的真实的时间检测。此外，酵母基因组最近被绘制在三维空间中，揭示了细胞核中非随机染色体区域的模式，着丝粒聚集在纺锤体极体附近，染色体臂伸展，端粒拴在核膜上。这个建议的重点是直接测试的想法，空间接近有助于形成复发性染色体易位的两种方式。首先，以三维基因组图谱为指导，将两个DNA断裂位点放置在基因组的不同位置，彼此之间的空间距离不同。染色体易位形成的频率将与空间距离相关，如通过染色体构象捕获（3C）测定所测量的。接下来，在这些特定的位置，染色质结构将通过改变细胞周期时相和删除参与端粒与核周边的连接的因子来改变。将分别使用3C试验和易位遗传菌株评估空间邻近性和染色体易位频率。这项研究将阐明导致染色体易位的分子机制，并为表征人类的等效过程奠定基础。

DESCRIPTION (provided by applicant): Effect of Spatial Proximity on Chromosomal Translocations Chromosomal translocations are a type of genomic rearrangement known to be involved in cancer development and progression, and they involve the exchange of genetic material between two non- homologous chromosomes. In certain cancers, especially leukemias, lymphomas, and sarcomas, specific translocations are recurrent, meaning different patients present with translocations involving the same two loci on the same two chromosomes. This recurrence of certain translocations leads to the hypothesis that certain regions of the genome are more susceptible to rearrangement, likely through a close spatial proximity in the nuclear space. Despite correlative evidence demonstrating close spatial proximity of commonly translocated regions of the genome using, for instance, Fluorescent In-Situ Hybridization (FISH) techniques, the idea that spatial proximity contributes to the formation of chromosomal translocations has not be directly or thoroughly tested. Our laboratory developed a novel genetic system with which we can detect Non-Homologous End- Joining (NHEJ)-mediated reciprocal chromosomal translocations in the S. cerevisiae model organism. This system allows for the simultaneous induction of DNA duplex breaks on separate chromosomes, and the real time detection of reciprocal chromosomal translocations. Additionally, the yeast genome has recently been mapped in three-dimensional space, revealing the patterns of non-random chromosomal territories in the nucleus, with the centromeres clustered near the spindle pole body, the chromosome arms outstretched, and the telomeres tethered to the nuclear membrane. The focus of this proposal is to directly test the idea that spatial proximity contributes to the formation of recurrent chromosomal translocations in two ways. First, using the three-dimensional genome map as a guide, two DNA break-sites will be placed at different locations in the genome, at different spatial distances from each other. The frequency of chromosomal translocation formation will be correlated to the spatial distance, as measure by the Chromosome Conformation Capture (3C) assay. Next, at these specified locations, the chromatin architecture will be modified by changing the cell cycle phase and by deleting factors involved in the telomere-tethering to the nuclear periphery. Spatial proximity and chromosomal translocation frequency will be assessed using the 3C assay and the translocation genetic strain, respectively. This study will shed light on the molecular mechanism leading to chromosomal translocations and set the stage for characterizing the equivalent processes in humans.