Identifying Molecular Signatures Underlying Preleukemic Clonal Expansion

项目摘要 当一个细胞的后代在数量上过度增加时，就会发生克隆扩增。起着 在许多造血系统疾病如骨髓增生性疾病的早期阶段起着至关重要的作用， 骨髓增生异常综合征和白血病。在疾病发生过程中，克隆扩张通常由以下启动： 体细胞突变，这反过来又允许积累额外的分子变化，导致 疾病进展。然而，并非所有的克隆扩增都会导致血液疾病或白血病。最近 研究表明，造血干细胞和祖细胞（HSPCs）通常表现出克隆扩增， 在骨髓移植后和无任何明显疾病的健康老年人中。知之甚少 关于正常和白血病前期克隆扩增之间的差异，特别是关于 它们差异背后的分子事件。拟议的研究项目将解决假设 白血病前克隆性扩增与不同的基因表达和/或表观遗传相关， 除了已知的白血病相关突变，如Tet 2突变之外，还存在其他特征。克隆 在Tet 2诱导型敲除小鼠中使用遗传条形码技术追踪扩增。此外，委员会认为， 遗传条形码技术与基于液滴的单细胞RNA测序（scRNA- seq）和用于可转座接近的染色质测序的单细胞测定（scATAC-seq）来鉴定 分子事件与不同的克隆扩张。已识别的分子特征 将使用dCas 9-KRAB小鼠模型功能性地测试白血病前克隆扩增。的 一项拟议的研究比较了不同克隆的细胞扩增，以鉴定罕见的细胞和分子 Tet 2诱导的白血病前期克隆性扩增相关事件。这些实验将揭示 使用常规的大体积分析检测不到的触发白血病前期克隆扩增的分子驱动因素 细胞群这些发现将有助于改善造血系统疾病的诊断，特别是TET 2 相关疾病，并可能确定其治疗的新的治疗靶点。

Project Summary Clonal expansion occurs when the progeny of a cell excessively increases in number. It plays a crucial role in theearly phase of many hematopoietic disorders such as myeloproliferative disorders, myelodysplastic syndromes, and leukemias. During disease genesis, clonal expansion is often initiated by somatic mutations,which in turn allow the accumulation of additional molecular changes that lead to disease progression. However, not all clonal expansions lead to blood disorders or leukemia. Recent studies show that hematopoietic stem and progenitor cells (HSPCs) commonly exhibit clonal expansion after bone marrow transplantation and in healthy elderly without any apparent disease. Little is known about the differences between normal and preleukemic clonal expansion, particularly with respect to the molecular events underlying their differences. The proposed research project will address the hypothesis that preleukemic clonal expansion is associated with distinct gene expression and/or epigenetic characteristics in addition to the known leukemia-associated mutations, such as Tet2 mutations. Clonal expansion will be tracked using a genetic barcoding technology in Tet2 inducible knockout mice. Moreover, the genetic barcoding technology is integrated with droplet-based single cell RNA-sequencing (scRNA- seq) and with single cell assay for transposable accessible chromatin-sequencing (scATAC-seq) to identify molecular events that are associated with the distinct clonal expansion. The identified molecular signatures of pre-leukemic clonal expansion will be functionally tested using the dCas9-KRAB mouse model. The proposed study compares cellular expansion across different clones to identify rare cellular and molecular events associated with Tet2-induced pre-leukemic clonalexpansion. These experiments will reveal the key molecular drivers that trigger preleukemic clonal expansion undetectable using conventional assays of bulk cell populations. The findings will help improve diagnosis of hematopoietic diseases, particularly TET2 related diseases, and may identify new therapeutic targets for their treatments.