Synergestic roles of SRF2 and RUNX1 in blood cell development and pathology

摘要 骨髓增生异常综合征(MDS)是一种以发育不良、效率低下为特征的慢性造血系统疾病 造血和转化为急性髓系白血病(AML)的倾向。的最新进展 基因组测序显示了与这种疾病相关的大量突变，大致可以是 分为三类：(1)参与信号传递的基因(即Flt3、JAK2、KRAS)，(2)在 染色质和前mRNA剪接(即RUNX1、ASXL1、SRSF2、U2AF1)的水平，以及(3)基因 负责建立/维护基因组甲基组(即DNMT3a、TET2、IDH1/2)。假设MDS为 其临床特征具有高度的异质性，一个基本的问题是个体突变是否会导致 疾病通过不同的机制，或者是否许多突变在一些汇聚的途径中发挥作用。支持 后一种可能性是许多这些因果突变在MDS患者中共同出现。 作为面向疾病(Zhang)和机制中心(FU)的实验室，我们一直在利用我们的 将专业知识结合在一起，在这项资助的R01下合作，解决该领域的一些紧迫问题， 重点关注RUNX1和SRSF2。在上一个供资周期(2013年9月至今)，我们提出了两个概念 突破性进展。首先，通过将特定突变与MDS患者的剪接反应联系起来，我们发现非 剪接因子突变引起的重叠反应汇聚到细胞的共同途径 循环和DNA损伤反应。第二，我们意外地发现，除了他们在 剪接，关键剪接因子的所有原因突变都会触发过度的R-环形成，导致复制 应激和细胞周期检查点激活。这些发现指向dna损伤反应的失调。 作为MDS病因学的共同基础。重要的是，这种阐明的共同点奠定了关键 为我们下一阶段的调查奠定基础，这一阶段将了解个体突变对 MDS和它们之间的潜在协同作用，尽管它们在调节基因表达方面扮演着不同的角色。建房 根据我们已公布和未公布的结果，我们建议在下一步实现以下具体目标 阶段：目标1.RUNX1的功能及其与SRSF2在防止DNA损伤中的协同作用；目标2.突变 SRSF2和表观遗传调节因子协同驱动异常基因表达；目标3.潜力 绕过R环诱导的细胞周期检查点激活的机制。

Summary Myelodysplastic Syndromes (MDS) are chronic hematopoietic disorders characterized by dysplasia, inefficient hematopoiesis, and the propensity to transform into acute myeloid leukemia (AML). Recent advances in genomic sequencing revealed a large number of mutations associated with the disease, which can be roughly grouped into three classes: (1) genes involved in signaling (i.e. FLT3, JAK2, KRAS), (2) genes functioning at the levels of chromatin and pre-mRNA splicing (i.e. RUNX1, ASXL1, SRSF2, U2AF1), and (3) genes responsible for establishing/maintaining the genome methylome (i.e. DNMT3a, TET2, IDH1/2). Given MDS is highly heterogeneous in its clinical features, a fundamental question is whether individual mutations cause the disease via distinct mechanisms or whether many mutations function in some converging pathways. Support of the latter possibility is the co-occurrence of many of these causal mutations in MDS patients. As disease-oriented (Zhang) and mechanism-central (Fu) labs, we have been taking advantage of our combined expertise to work together under this funded R01 to attack some pressing questions in the field, focusing on RUNX1 and SRSF2. In the past funding cycle (9/2013-present), we have made two conceptual breakthroughs. First, by linking specific mutations to splicing responses in MDS patients, we found that non- overlapping responses induced by splicing factor mutations are converged to the common pathways of cell cycle and DNA damage response. Second, we unexpectedly uncovered that, besides their traditional roles in splicing, all causal mutations in key splicing factors trigger excessive R-loop formation, leading to replication stress and cell cycle checkpoint activation. These findings point to dysregulation of the DNA damage response as a common ground for MDS etiology. Importantly, such elucidated common ground has laid a critical foundation for our next phase of investigation, which is to understand the contribution of individual mutations to MDS and potential synergy among them, despite their diverse roles in regulating gene expression. Building upon both our published and unpublished results, we propose to pursue the following specific aims in the next phase: Aim 1. Function of RUNX1 and its synergy with SRSF2 in preventing DNA damage; Aim 2. Mutant SRSF2 and epigenetic regulators to synergistically drive aberrant gene expression; Aim 3. Potential mechanism for bypassing R-loop-induced cell cycle checkpoint activation.