Functional and molecular basis of ineffective erythropoiesis in SF3B1-mutant myelodysplastic syndromes

摘要 大多数患者患有骨髓增生异常综合征(MDS)，这是一组不同类型的血液疾病 以无效和克隆性造血为特征，携带影响RNA剪接的体细胞突变 因素。最常见的突变剪接因子是SF3B1，它是剪接体的核心成分 在有环状铁粒母细胞的MDS中优先突变(MDS-RS)。尽管SF3B1突变属于 虽然MDS中最常见的遗传损害，但人们对它们的了解相对较少。我们的不完整 对SF3B1突变的理解在一定程度上是由于缺乏概括标志的模型系统 疾病表型，包括环状铁粒母细胞形成和无效的红细胞生成。因此，它是 不清楚SF3B1突变是如何改变RNA剪接机制的，哪些特定的错误剪接基因导致了标志 疾病表型，以及SF3B1突变细胞是否可以通过靶向治疗而被杀死。 在这里，我们建议阐明的功能基础以及机制和表型后果 MDS-RS中的SF3B1突变。我们的团队由一位在血液病方面有专长的干细胞生物学家组成。 建模(Doulatov)，在RNA剪接和功能基因组学方面拥有专业知识的基础科学家(Bradley)和 内科医生--在红细胞生成和血红素生物学方面有专长的科学家(阿布科维茨)。在初步研究中，我们 产生的MDS-RS患者来源的诱导多能干细胞(IPSCs)概括了标志性疾病 红系分化过程中的表型，确定了导致无效的特定错接基因 红细胞生成，并进行功能基因组筛选以鉴定SF3B1突变的分子脆弱性 细胞。我们建议在这些初步研究的基础上如下：目标1，定义分子后果 目的2，确定环的功能基础 SF3B1突变MDS-RS的铁粒母细胞形成和无效的红细胞生成；目标3，确定治疗 治疗带有SF3B1突变的MDS-RS的机会。这些研究的意义在于，它们将 阐明MDS-RS中SF3B1突变的机制和功能后果。健康 相关性是，拟议的工作可能会确定通过专门针对MDS治疗的新机会 SF3B1-突变细胞。随着MDS发病率的上升和SF3B1突变MDS-RS患者面临终身 输血负担和相关的发病率和死亡率，公共卫生需要开发新的 治疗这种疾病的方法。

SUMMARY The majority of patients with myelodysplastic syndromes (MDS), a heterogeneous group of blood disorders characterized by ineffective and clonal hematopoiesis, carry a somatic mutation affecting an RNA splicing factor. The most commonly mutated splicing factor is SF3B1, a core component of the spliceosome that is preferentially mutated in MDS with ring sideroblasts (MDS-RS). Although SF3B1 mutations are among the most common genetic lesions in MDS, they are nonetheless relatively poorly understood. Our incomplete understanding of SF3B1 mutations is due in part to the absence of a model system that recapitulates hallmark disease phenotypes, including ring sideroblast formation and ineffective erythropoiesis. As a consequence, it is unclear how SF3B1 mutations alter RNA splicing mechanisms, which specific mis-spliced genes drive hallmark disease phenotypes, and whether SF3B1-mutant cells can be killed by targeted therapies. Here, we propose to elucidate the functional basis as well as mechanistic and phenotypic consequences of SF3B1 mutations in MDS-RS. Our team consists of a stem cell biologist with expertise in hematologic disease modeling (Doulatov), a basic scientist with expertise in RNA splicing and functional genomics (Bradley), and a physician-scientist with expertise in erythropoiesis and heme biology (Abkowitz). In preliminary studies, we generated MDS-RS patient-derived induced pluripotent stem cells (iPSCs) that recapitulate hallmark disease phenotypes during erythroid differentiation, identified specific mis-spliced genes that contribute to ineffective erythropoiesis, and performed functional genomic screens to identify molecular vulnerabilities of SF3B1-mutant cells. We propose to build on those preliminary studies as follows: Aim 1, Define the molecular consequences of SF3B1 mutations for mRNA splicing, stability, and translation; Aim 2, Determine the functional basis of ring sideroblast formation and ineffective erythropoiesis in SF3B1-mutant MDS-RS; Aim 3, Identify therapeutic opportunities for treating MDS-RS with SF3B1 mutations. The significance of these studies is that they will elucidate the mechanistic and functional consequences of SF3B1 mutations in MDS-RS. The health relatedness is that the proposed work may identify new opportunities for treating MDS by specifically targeting SF3B1-mutant cells. As the incidence of MDS is rising and patients with SF3B1-mutant MDS-RS face life-long transfusion burdens and associated morbidity and mortality, there is a public health need to develop new therapies for this disorder.