Targeting splicing in myelodysplasia through GSK-3

(请保存在Word中，不要保存为PDF) 剪接因子SRSF2和SF3B1的反复突变在骨髓发育不良中很常见 (MDS)。这些功能突变的获得是相互排斥的，并且总是杂合的， 这表明具有剪接因子突变的细胞需要一些野生型剪接活性来 活下去。剪接设备的进一步扰动是致命的，造成了治疗的脆弱性 用于剪接因子突变的肿瘤。因此，小分子剪接抑制剂目前正在被 探索过治疗剪接因子突变的MDS，但它们有不可耐受的副作用和 到目前为止效果有限，这表明需要新的方法来抑制剪接。我们发现 信号蛋白糖原合成酶-3(GSK-3)磷酸化多剪接 影响和调节广泛的mRNAs的选择性剪接。GSK-3的抑制作用 在杂合子的造血细胞系中选择性地破坏剪接和促进细胞死亡 SRSF2或SF3B1突变。我们的长期目标是将GSK-3定义为 新型的全球剪接调控因子并测试GSK-3抑制剂是否具有选择性 对带有剪接因子突变的MDS细胞来说，体内是致命的。我们的初步数据支持这一点 在造血细胞系中的假说，但重要的是在原代建立这些发现 MDS和CMML患者的人类细胞。我们将表达SRSF2wt或致病性 MDS患者原代细胞中SRSF2P95H突变是否表达 致病突变赋予了对GSK-3抑制的敏感性，在其他相同的基因背景下。 这些实验将提供关键的初步数据，并为以后的工作奠定基础 研究GSK-3作为全球剪接调节因子和作为潜在调控因子的作用的实验 剪接因子突变体MDS的治疗靶点。

(PLEASE KEEP IN WORD, DO NOT PDF) Recurrent mutations in the splicing factors SRSF2 and SF3B1 are common in myelodysplasia (MDS). These gain of function mutations are mutually exclusive and invariably heterozygous, indicating that cells with splicing factor mutations require some wild-type splicing activity to survive. Further perturbation of the splicing apparatus is lethal, creating a therapeutic vulnerability for splicing factor mutant neoplasms. Thus, small molecule splicing inhibitors are currently being explored to treat splicing factor mutant MDS, but they have had intolerable side effects and limited efficacy so far, indicating that new approaches to inhibit splicing are needed. We found that the signaling protein glycogen synthase kinase-3 (GSK-3) phosphorylates multiple splicing factors and regulates the alternative splicing of a broad range of mRNAs. Inhibition of GSK-3 disrupts splicing and promotes cell death selectively in hematopoietic cell lines with heterozygous mutations in SRSF2 or SF3B1. Our long-term goals are to define the role of GSK-3 as a novel, global regulator of splicing and to test whether GSK-3 inhibitors are selectively lethal in vivo for MDS cells with splicing factor mutations. Our preliminary data support this hypothesis in hematopoietic cell lines, but it is important to establish these findings in primary human cells from patients with MDS and CMML. We will express SRSF2wt or the pathogenic SRSF2P95H mutation in primary cells from patients with MDS to ask whether expression of the pathogenic mutation confers sensitivity to GSK-3 inhibition in an otherwise isogenic context. These experiments will provide critical preliminary data and lay the groundwork for future experiments to investigate the role of GSK-3 as a global regulator of splicing and as a potential therapeutic target in splicing factor mutant MDS.