Biologic and Therapeutic Consequences of Distinct Hotspot SF3B1 Mutations in MDS

项目摘要 骨髓增生异常综合征（MDS）是最常见的克隆性血液病，其特征是 异常干细胞对骨髓的支配和血细胞生成的损害。患者 MDS患有贫血、感染、出血和进行性疾病引起的多器官衰竭的组合。 结果很差，治疗也不够。开发新疗法的关键是更好地了解 这些突变导致了这些疾病。大约一半的MDS患者在剪接体中存在突变 这些基因中，SF3B1是最常见的突变。突变体SF3B1是新形态的，破坏RNA 剪接，以创造我们所说的JEM（剪接接头富集在Muje-spliceosome细胞），但如何 JEM产生MDS表型是未知的。SF3B1突变被认为是一个有利的预后标志物， MDS。然而，在SF3B1突变的病理特征和临床结果中存在相当大的异质性， 无法解释的骨髓增生异常综合征。由于这种异质性影响了有效的疾病管理，其原因需要 更好地被理解。我们的建议的前提是，理解SF3B1突变型MDS的关键是 研究不同SF3B1突变之间的差异。这种基因在影响多种疾病的热点发生突变， 我们的初步数据表明，特定的突变与不同的临床特征，RNA， 剪接模式和对治疗的反应我们也有数据表明，SF3B1突变会破坏代谢， 可能影响铁粒幼细胞性贫血和代谢脆弱性的特定方式，我们已经开发了新的 SF3B1突变造血的人类模型，以研究这些过程。拟议工作 结合了专门从事细胞生物学，遗传学和人类学的医生科学家（道尔顿博士）的专业知识， 疾病的细胞建模与专门从事骨临床研究的临床研究者（DeZern博士）的建模 骨髓衰竭症我们将共同追求三个目标：1）描绘私人和私人的景观， 在MDS中热点SF3B1突变之间共享JEM。我们将使用原发性MDS样品的RNA-seq， 等基因人类细胞模型来绘制不同SF3B1突变的RNA剪接景观，并将其用作 了解它们破坏的途径。2)确定不同的SF3B1突变在 人造血细胞的生长和分化。我们将使用原代MDS样本和同基因细胞， 确定SF3B1突变型铁粒幼细胞性贫血、细胞适应性和代谢脆弱性的机制 造血细胞3)定义MDS中不同SF3B1突变的临床病理特征。借力 NHLBI国家MDS研究的高质量数据，我们将确定不同的热点SF3B1突变 影响MDS的病理和临床特征。圆满完成这些目标 有望揭示RNA剪接的病理生理机制，重新定义疾病分类和预后， 并改善MDS的治疗方法。

Project Summary The myelodysplastic syndromes (MDS) are the most common clonal blood disorders, characterized by dominance of the bone marrow by abnormal stem cells and impairment of blood cell production. Patients with MDS suffer from combinations of anemia, infection, bleeding, and multiorgan failure from progressive disease. Outcomes are poor, and treatments are inadequate. Key to developing new treatments is better understanding of the mutations which create these diseases. Roughly half of MDS patients have mutations in spliceosome genes, and of these, SF3B1 is the most commonly mutated. Mutant SF3B1 is neomorphic, disrupting RNA splicing to create what we refer to as JEMs (splice Junctions Enriched in Mutant-spliceosome cells), though how JEMs produce MDS phenotypes is unknown. SF3B1 mutation is regarded as a favorable prognostic marker in MDS. Yet, there is considerable heterogeneity in the pathologic features and clinical outcomes of SF3B1-mutant MDS that remains unexplained. As this heterogeneity beguiles effective disease management, its causes need to be better understood. The premise of our proposal is that a key to understanding SF3B1-mutant MDS is to study the differences between distinct SF3B1 mutations. This gene is mutated in hotspots affecting multiple amino acids, and our preliminary data show that specific mutations associate with distinct clinical features, RNA splicing patterns, and responses to therapy. We also have data that SF3B1 mutations disrupt metabolism in specific ways that likely affect sideroblastic anemia and metabolic vulnerabilities, and we have developed novel human models of SF3B1-mutant hematopoiesis with which to study these processes. The proposed work combines the expertise of a physician-scientist (Dr. Dalton) who specializes in cell biology, genetics, and human cell modeling of disease with that of a clinical investigator (Dr. DeZern) who specializes in clinical studies of bone marrow failure disorders. Together, we will pursue three aims: 1) Characterize the landscape of private and shared JEMs among hotspot SF3B1 mutations in MDS. We will use RNA-seq of primary MDS samples and isogenic human cell models to map the RNA splicing landscape of different SF3B1 mutations and use this as a ‘way in’ to understanding the pathways they disrupt. 2) Establish the role of distinct SF3B1 mutations in the growth and differentiation of human hematopoietic cells. We will use primary MDS samples and isogenic cells to determine mechanisms of sideroblastic anemia, cell fitness, and metabolic vulnerability in SF3B1-mutant hematopoietic cells. 3) Define the clinicopathologic features of distinct SF3B1 mutations in MDS. Leveraging the high-quality data from the NHLBI National MDS Study, we will determine how distinct hotspot SF3B1 mutations affect pathologic and clinical features of MDS through multivariate analysis. Successful completion of these aims promises to reveal pathophysiologic mechanisms of RNA splicing, redefine disease classification and prognosis, and improve treatment approaches in MDS.