Mutual reinforcement between somatic mutations and transcription factors in clonal hematopoiesis

项目总结/摘要 最近的高通量外显子组测序已经揭示了克隆性大肠癌个体中的各种体细胞突变。 造血（CH）和骨髓增生异常综合征（MDS）患者。在这些突变中，C到T 突变是在CH和MDS中观察到的最常见的单突变类型。现在还没有 解释了为什么C到T突变优先在CH和MDS中富集，以及C到T转换如何改变 造血干细胞和祖细胞（HSPC）的适应性，并导致异常的克隆扩增。通过组合 MDS骨髓样本的体外生化和结构分析及表观基因组分析 研究小组发现，在C-T转换之间存在一种以前被低估的相互强化作用， 和转录因子（TF）的基因组结合，其有助于HSPC的克隆扩增， 加重CH和MDS。在Aim 1中，该团队将使用基因修饰的小鼠模型和CRISPR/Cas9- 基于基因组编辑的方法来探测HSPC中C到T转变和TF结合之间的因果关系。在 目标2，研究小组将测试C-to-T转换和DNA甲基化失调如何重塑基因组 转录因子的分布，随后改变下游转录产物，导致克隆扩增， HSPC。同时，研究小组将使用从CH和MDS患者中纯化的HSPC进一步验证研究结果 在离体和啮齿动物模型中制备。预计拟议的研究将大大推进我们的 对转录因子如何塑造基因组以及体细胞突变如何改变转录水平的机械理解 HSPC中的规则。从翻译的角度来看，这项研究的发现将导致 确定CH和MDS治疗的治疗弱点。

Project Summary/ Abstract Recent highthroughput exome sequencing has revealed various somatic mutations in individuals with clonal hematopoiesis (CH) and myelodysplastic syndromes (MDS) patients. Among these mutations, C-to-T mutations is among the most common type of single mutations observed in CH and MDS. It remains yet to be explained why C-to-T mutations are preferentially enriched in CH and MDS and how the C-to-T transition alters hematopoietic stem and progenitor cells (HSPCs) fitness and leads to aberrant clonal expansion. By combining in vitro biochemical and structural analyses with epigenomic profiling of bone marrow samples from MDS patients, the team discovered a previously-underappreciated mutual reinforcement between C-to-T transition and genomic binding of transcription factors (TFs), which contributes to the clonal expansion of HSPCs and aggravate CH and MDS. In Aim1, the team will use genetically-modified mouse models and CRISPR/Cas9- based genome editing methods to probe the causality between C-to-T transition and TF binding in HSPCs. In Aim 2, the team will test how the C-to-T transition and DNA methylation deregulation reshape the genomic distribution of TFs, subsequently altering downstream transcriptional outputs to cause clonal expansion in HSPCs. In parallel, the team will use HSPCs purified from CH and MDS patients to further validate findings made ex vivo and in rodent models. The proposed studies are anticipated to significantly advance our mechanistic understanding on how TFs shape the genome and how somatic mutations alter transcriptional regulation in HSPCs. From a translational perspective, discoveries made from this study will lead to the identification of therapeutic vulnerabilities for CH and MDS treatment.