Runx1 Binding Sites as Scaffolds That Mediate Chromosome Translocation

描述(申请人提供)：人类急性和慢性白血病的一个显著特征是发现它们是非随机的、躯体获得性染色体易位的结果。我们研究的长期目标是确定染色体易位的产生是否有共同的机制。作为一个生物学模型，我们使用了RUNX1基因，它编码了一种重要的造血转录因子，也是急性髓系白血病(AMI)最常见的染色体易位靶点。RUNX1基因位于21号染色体上，有趣的是，在(8；21)和(16；21)AML相关易位中，所有的基因组断裂点都在内含子5上。因此，一个关键的问题是什么因素使RUNX1基因参与染色体易位？我们的工作假设是，存在于断点区的染色质结构是t(8；21)易位的决定因素。此外，我们假设，基因的亚核定位可能决定了基因对dsDNA断裂的易感性，以及在产生易位时对伴侣基因的选择。对染色质的结构特征与RUNX1、ETO和重组AML/ETO基因座的核定位进行详细比较，将使我们能够确定是否存在共同特征，这些特征可能是在断点区观察到的更多可及性的原因。基于我们初步数据的拟议实验将结合合作实验室的专业知识来调查可能决定RUNX1基因座重组频率的顺式和反式作用因素。父母资助的重点是染色质组织、RUNX因子的核区划和基因表达之间的相互关系。在FIRCA的这项提案中，我们扩大了这些研究的范围，以解决RUNX调节因子、核定位和染色体易位易感性之间的关系。这项研究将主要在智利康塞普西翁大学与索拉亚·古铁雷斯合作进行，作为NIH赠款5P01 AR48818项目的延伸。

DESCRIPTION (provided by applicant): A striking characteristic of the human acute and chronic leukemias is the finding that they are the result of nonrandom, somatically acquired chromosomal translocations. The long-term goal of our research is to determine if there is a common mechanism involved in the generation of chromosomal translocations. As a biological model, we are using the RUNX1 gene, which encodes an important hematopoietic transcription factor and is the most frequent target of chromosomal translocations in acute myeloid leukemia (AMI). The RUNX1 gene is located on chromosome 21, and interestingly, for both the (8; 21) and (16; 21) AML-related translocations, all the genomic breakpoints are found in intron 5. Therefore, a key question is what are the factors that predispose the RUNX1 gene to be involved in chromosomal translocations? Our working hypothesis is that the chromatin structure present at the breakpoint regions is determinant for the t(8;21) translocation. Moreover, we hypothesize that the sub-nuclear localization of a gene may be determinant both of the gene susceptibility to dsDNA breaks and in the selection of the partner gene when a translocation is generated. A detailed comparison between the structural characteristics of chromatin and the nuclear positioning of the RUNX1, ETO and the recombinant AML/ETO locus will allow us to identify the presence of common features that may account for the increased accessibility observed at the breakpoint regions. The proposed experiments based on our preliminary data will combine the expertise of the collaborating laboratories to investigate the cis and trans acting factors that can be determinants of the RUNX1 locus recombination frequency. The focus of the parent grant is the interrelationship between chromatin organization, nuclear compartmentalization of Runx factors, and gene expression. In this FIRCA proposal, we extend the scope of these studies to address the relationship between Runx regulatory factors, nuclear localization, and susceptibility to chromosomal translocations. This research will be done primarily in Chile at the Universidad de Concepcion in collaboration with Soraya Gutierrez as an extension of NIH grant 5P01 AR48818, projects.