The functional role of DDX41 in myelodysplastic syndromes

DDX41 在骨髓增生异常综合征中的功能作用

• 批准号: 10750070
• 负责人: Honghao Bi
• 金额: $ 7.63万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-30 至 2026-09-29
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10750070
• 关键词: Acute Myelocytic Leukemia; Affect; Alleles; Apoptosis; Binding Sites; Biogenesis; Biological Assay; Body Weight; Bone Marrow; CD34 gene; Cell Death; Cell Lineage; Cells; Characteristics; Complete Blood Count; DNA Structure; Data; Defect; Development; Dysmyelopoietic Syndromes; Erythroblasts; Erythroid Cells; Erythropoiesis; Flow Cytometry; Functional disorder; G-Quartets; Genes; Genome; Germ-Line Mutation; Guanine; Hematologic Neoplasms; Hematopoiesis; Hematopoietic; Hematopoietic System; Hematopoietic stem cells; Human; In Vitro; Knock-out; Knockout Mice; Lead; Mediating; Modeling; Molecular; Mus; Mutate; Mutation; Pathogenesis; Pathway interactions; Patients; Reporting; Research; Ribosomal Proteins; Ribosomes; Risk; Role; Running; Site; Small Nucleolar RNA; Somatic Mutation; Spleen; Stress; Susceptibility Gene; Symptoms; TP53 gene; Technology; Testing; Up-Regulation; Zebrafish; cytopenia; experimental study; helicase; in vivo; loss of function; mouse model; novel; novel therapeutics; peripheral blood; response; targeted treatment

Project Summary Myelodysplastic syndromes (MDS) are a group of hematologic malignancies characterized by clonal hematopoiesis, one or more cytopenias, and increased risks to transform into acute myeloid leukemia (AML). Multiple mutations have been identified to be associated with MDS. One of these mutations occurs on DEAD- box helicase 4 (DDX41) gene. At least 70 DDX41 germline or somatic mutations have been reported, making DDX41 one of the most frequently mutated MDS predisposition genes. Germline DDX41 mutations lead to its loss of function whereas somatic mutations often produce hypomorphic changes. Recent studies in zebrafish showed that knockout of DDX41 induces increased R-loop accumulation and aberrant hematopoiesis. Another research using conditional DDX41 knockout mice reported that DDX41 biallelic mutations disrupt snoRNA biogenesis and lead to apoptosis in hematopoietic cells. These and other studies started to shed lights on the mechanisms of DDX41 mutated pathogenesis of MDS. However, it still remains unknown how loss of DDX41 in hematopoietic cells causes apoptosis and what lineages are most sensitive to its deficiency. Therefore, it is essential to dissect the molecular and cellular mechanisms of DDX41’s functions, which could be helpful to develop targeted therapy for DDX41 mutated MDS. G-quadruplexes (G4) are four-stranded, noncanonical secondary DNA structures formed in guanine-rich sequences. We showed in our preliminary study that loss of DDX41 led to aberrant upregulation of G4 in the hematopoietic system. We further revealed that G4 is enriched during erythropoiesis. G4 accumulation due to DDX41 deficiency severely disrupted erythropoiesis with less effects in other lineages in vitro and ex vivo. Importantly, we validated these in vitro findings and revealed that the lethality of hematopoietic-specific DDX41 knockout mice is likely due to the defects in erythropoiesis. Our preliminary mechanistic studies also revealed that DDX41 deficiency-mediated G4 upregulation in erythroid cells compromised the expression of various ribosome proteins that led to p53-dependent apoptosis in erythroid cells. Based on these data, we hypothesize that DDX41 deficiency in MDS leads to G4 accumulation and defects in ribosome biogenesis, which induces p53-mediated cell death specifically in erythroid cells. To test our hypothesis, we propose three specific aims. Aim 1 will focus on the study of the functions of DDX41 in various lineages of hematopoietic cells by generating lineage specific DDX41 knockout mice. In aim 2, we will investigate how DDX41 regulates the accumulation of G4 in erythropoiesis. Aim 3 will focus on the mechanistic studies on DDX41-G4-ribosomal biogenesis-p53 pathway. Successful completion of our proposed research will provide novel mechanisms of DDX41’s functional role in normal and abnormal hematopoiesis, which will be impactful for the development of novel therapies for DDX41 mutation-related hematologic malignancies.

项目摘要 骨髓增生综合征（MDS）是一组血液学恶性肿瘤，其特征是克隆 造血，一种或多种细胞质，并增加了转化为急性髓样白血病（AML）的风险。 已确定多个突变与MDS相关。这些突变之一发生在死亡 - 盒子解旋酶4（DDX41）基因。据报道至少有70种DDX41种系或体细胞突变，使得 DDX41最常见的MDS易感基因之一。种系DDX41突变导致其 功能的丧失，而体细胞突变通常会导致肌阵变量变化。斑马鱼的最新研究 表明DDX41的敲除诱导R环的积累增加和异常的造血。其他 使用条件DDX41基因敲除小鼠的研究报告说DDX41双重突变破坏了SNORNA 生物发生并导致造血细胞的凋亡。这些和其他研究开始在 DDX41 MDS的突变发病机理。但是，仍然尚不清楚ddx41在 造血细胞会导致凋亡以及哪些谱系对其缺乏最敏感。因此，是 剖析DDX41功能的分子和细胞机制必不可少的，这可能有助于 开发了针对DDX41突变MD的靶向治疗。 G四链体（G4）是四链，非规范的 以鸟嘌呤序列形成的次级DNA结构。我们在初步研究中表明了丧失 DDX41导致造血系统中G4的异常上调。我们进一步揭示了G4丰富 在红细胞生成期间。 DDX41缺乏引起的G4积累严重破坏了红细胞生成 在其他体外和离体的其他谱系中的影响。重要的是，我们验证了这些体外发现，并揭示了 造血特异性DDX41敲除小鼠的致死性可能是由于促红细胞生成的缺陷。我们的 初步机械研究还表明，DDX41缺乏介导的红细胞细胞上调的G4上调 损害了各种核糖体蛋白的表达，这些核糖体蛋白导致红细胞细胞中p53依赖性凋亡。 基于这些数据，我们假设MDS中的DDX41缺乏导致G4积累和缺陷 核糖体生物发生，该生物发生在红细胞细胞中诱导p53介导的细胞死亡。为了检验我们的假设， 我们提出了三个具体目标。 AIM 1将重点研究DDX41在各种谱系的功能的研究上 造血细胞通过产生谱系特定的DDX41敲除小鼠。在AIM 2中，我们将调查如何 DDX41调节G4在红细胞生成中的积累。 AIM 3将侧重于有关的机械研究 DDX41-G4-核糖体生物发生p53途径。成功完成我们拟议的研究将提供 DDX41在正常和异常造血的功能作用的新型机制，这对 DDX41突变相关的血液学恶性肿瘤的新型疗法的发展。