Examining role of splicing factor mutations in myelodysplastic syndrome (PQ11)

描述(由申请人提供)：细胞转录组的调节剪接对正常生长和发育是必不可少的。剪接模式的异常表达与癌症和许多其他疾病有关。这些异常的剪接模式可能是由于前信使核糖核酸剪接位点或剪接机制的蛋白质成分的突变引起的。最近对骨髓增生异常综合征(MDS)患者的外显子组分析表明，剪接机制核心蛋白质的点突变与疾病发病机制之间存在联系。8个剪接蛋白的体细胞突变在MDS病例中被发现是复发的。这种关联使得理解这些剪接体蛋白突变导致疾病表型的机制变得至关重要。我们假设剪接因子中MDS突变的致病作用是通过其剪接功能的变化来介导的。MDS突变影响这些蛋白质的正常功能，导致转录本的异常剪接模式的产生，这在造血中是重要的。这导致了HSPC异常的生长控制。该项目的目标是确定MDS突变对剪接因子功能的分子影响，并确定它们在造血过程中诱导的全基因组剪接异常，这些异常与MDS的发病机制有关。我们将重点关注SF3B1和U2AF35蛋白的突变。这两种蛋白突变的分布在不同的MDS类型中不同。SF3B1突变在以环状铁粒母细胞(RS)为特征的MDS类型中常见，而U2AF35突变发生在没有RS的MDS中。这种相互排斥的发生和它们非常特殊的疾病结果表明它们的致病作用和可能不同的疾病进展机制存在差异。我们将使用先进的高密度RNA测序技术来鉴定MDS突变导致的造血干/祖细胞剪接谱的异常。这些突变对HSPC正常增殖和分化的影响将被确定。异常剪接的机制将通过使用生化技术定义MDS突变引起的U2AF35和SF3B1剪接功能的变化来确定。通过这种方法，我们希望定义正常造血过程中由U2AF35和SF3B1控制的特定剪接事件，然后阐明它们的突变是如何在MDS发病中起作用的。 公共卫生相关性：骨髓增生异常综合征(MDS)是一种表型多样的血细胞癌，由HSPC的异常生长和分化引起。在美国，每年约有12000例MDS病例被诊断出来。为了开发更好的预后标记物，并确定新的可用药靶点，了解正常造血细胞向MDS转化的机制是至关重要的。

DESCRIPTION (provided by applicant): Regulated splicing of the cellular transcriptome is essential for normal growth and development. Aberrant expression of splicing patterns is linked to cancers and many other diseases. These abnormal splicing patterns may arise from mutations in pre-mRNA splice sites or in the protein components of the splicing machinery. Recent exome analysis of myelodysplastic syndrome (MDS) patients indicates a link between point mutations in core proteins of the splicing machinery and disease pathogenesis. Somatic mutations in eight splicing proteins were found to be recurrent in MDS cases. This association makes it essential to understand the mechanisms by which these spliceosomal proteins mutations lead to a disease phenotype. We hypothesize that the pathogenic effects of MDS mutations in splicing factors are mediated through changes in their splicing functions. The MDS mutations affect the normal functions of these proteins, resulting in generation of abnormal splicing patterns of transcripts that are important in hematopoiesis. This causes aberrant growth control in HSPCs. The goal of this project is to determine the molecular effects of MDS mutations on splicing factor function and to identify genome-wide splicing aberrations they induce during hematopoiesis that contribute to MDS pathogenesis. We will focus on mutations in SF3B1 and U2AF35 proteins. Distribution of mutations in these two proteins differs amongst the MDS types. SF3B1 mutations are frequent in MDS types that are characterized by ringed sideroblasts (RS), whereas U2AF35 mutations occur in forms of MDS without RS. This mutually exclusive occurrence and their very specific disease outcomes indicate differences in their pathogenic effect and likely distinct mechanisms of disease progression. We will use advanced high density RNA sequencing techniques to identify the MDS mutation induced aberrations in splicing profile of hematopoietic stem/progenitor cells. Effect of these mutations on normal proliferation and differentiation of HSPCs will be determined. Mechanisms underlying aberrant splicing will be determined by defining the MDS mutation- induced changes in U2AF35 and SF3B1 splicing functions using biochemical techniques. Using this approach we expect to define specific splicing events controlled by U2AF35 and SF3B1 during normal hematopoiesis and then elucidates how their mutation contributes to MDS pathogenesis. PUBLIC HEALTH RELEVANCE: Myelodysplastic syndromes (MDS) are a phenotypically diverse group of blood cell cancers that arise from abnormal growth and differentiation of HSPCs. In United States, about 12,000 MDS cases are diagnosed every year. To develop better prognostic markers, and to identify new druggable targets, it is essential to understand the mechanisms that lead to transformation of normal hematopoietic cells to MDS.