The Role of DDX41 in Inherited Myelodysplastic Syndromes

DDX41 在遗传性骨髓增生异常综合征中的作用

基本信息

批准号：
10226159
负责人：
Timothy Michael Chlon
金额：
$ 15.04万
依托单位：
CINCINNATI CHILDRENS HOSP MED CTR
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-01 至 2024-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10226159
关键词：
AML/MDS Acute Myelocytic Leukemia Adult Affinity Alleles Amino Acid Substitution Binding Biochemical Biogenesis Biological Assay Blood Cell Cycle Progression Cell Death Cell Differentiation process Cell physiology Cells DNA Damage DNA Modification Methylases DNA biosynthesis DNMT3a Data Defect Development Disease Dysmyelopoietic Syndromes Dysplasia Embryo Frameshift Mutation Functional disorder Genetic Diseases Genomic Instability Germ-Line Mutation Goals Growth Helicase Gene Hematologic Neoplasms Hematological Disease Hematopoiesis Hematopoietic Hematopoietic stem cells Heterozygote Host Defense Human Immune Immune signaling Impairment In Vitro Incidence Individual Ineffective Hematopoiesis Infection Inherited Knock-out Lead Leukemic Cell Link Malignant - descriptor Malignant Neoplasms Missense Mutation Modeling Molecular Monitor Mus Mutation Myelogenous Pathogenesis Patients Phenotype Proteins Proteomics RNA Helicase RNA Splicing Ribosomes Role Somatic Mutation Testing Transplantation Virus Replication aging population cytopenia de novo mutation disease-causing mutation hematopoietic stem cell self-renewal high risk in vivo loss of function malignant phenotype mutant new therapeutic target novel self-renewal sensor small hairpin RNA stem cell function stem cell homeostasis targeted treatment therapeutic target

项目摘要

Project Summary Myelodysplastic syndromes (MDS) are genetic disorders caused by impaired hematopoietic stem/progenitor cells (HSPC), which can transform to acute myeloid leukemia (AML). MDS typically occurs in the ageing population, however MDS can also manifest as a result of inherited germline mutations in younger individuals. Mutations in the DEAD/H-box helicase gene DDX41 are among the most common alterations associated with inherited MDS. Inherited DDX41 mutations are heterozygous and are typically frameshifts, suggesting that these mutations result in loss of DDX41 function. DDX41 mutations are also observed in de novo MDS and AML, and are typically missense mutations frequently resulting in the amino acid substitution R525H. DDX41 is an RNA helicase that hydrolyzes ATP, and can function as an innate immune sensor, RNA splicing factor, and ribosome regulator. The precise mechanism(s) by which DDX41 mutations alter HSPC function and contribute to MDS/AML remains unknown. As such, the proposed project will define the role of DDX41 mutations in the pathogenesis of MDS/AML. To mimic the frameshift mutations observed in human MDS and determine the role of DDX41 in normal hematopoiesis, we generated hematopoietic-specific and conditional Ddx41-deficient mice. Our preliminary data has revealed that DDX41-deficiency (complete knockout) is not compatible with HSPC function and hematopoiesis, whereas DDX41 heterozygosity increases BM HPSC. In addition, through integrative proteomic and biochemical approaches we identified a novel DDX41-interacting protein in leukemic cells, SAMHD1, a dNTPase and host defense factor, which controls cellular pools of dNTPs. Collectively, our preliminary data indicate that DDX41 has a critical role in hematopoiesis and HSPC function. We hypothesize that diminished DDX41 expression and/or function contributes to ineffective hematopoiesis and to the pathogenesis of MDS and AML, in part due to increased SAMHD1 activity and altered cellular dNTP pools. Therefore, the objectives of this proposal are to model somatic and germline DDX41 mutations in normal and malignant hematopoiesis, and to elucidate the molecular function of DDX41 required for HSPC function. Through extensive hematopoietic approaches, we will define the role of DDX41 deficiency and R525H expression in MDS incidence and progression to AML (Aim 1). Since DNMT3A and DDX41 mutations commonly co-occur in MDS patients that have progressed to AML, we will determine whether DDX41 heterozygosity or R525H expression combined with DNMT3A-deficient mice will result in high-risk MDS or overt AML. Reduced cellular dNTP pools impair cell cycle progression and result in genomic instability; therefore, we will determine the role of SAMHD1 activity in DDX41-deficient HSPC or mutant MDS, and whether diminished cellular dNTPs pools lead to genomic instability and development of AML (Aim 2). By elucidating the function of DDX41 malignant hematopoiesis, we predict to uncover novel mechanisms underlying inherited and de novo MDS.

项目概要骨髓增生异常综合征 (MDS) 是由造血干/祖细胞受损引起的遗传性疾病细胞（HSPC），可转化为急性髓系白血病（AML）。 MDS 通常发生在衰老过程中然而，MDS 也可能是年轻个体遗传性种系突变的结果。 DEAD/H-box 解旋酶基因 DDX41 的突变是与遗传性MDS。遗传性 DDX41 突变是杂合的，并且通常是移码，这表明这些突变导致 DDX41 功能丧失。在新发 MDS 中也观察到 DDX41 突变 AML 和 AML 是典型的错义突变，经常导致氨基酸取代 R525H。 DDX41 是一种 RNA 解旋酶，可水解 ATP，并可充当先天免疫传感器、RNA 剪接因子和核糖体调节剂。 DDX41 突变改变 HSPC 功能并贡献的精确机制 MDS/AML 的影响仍未知。因此，拟议的项目将定义 DDX41 突变在 MDS/AML 的发病机制。模拟人类 MDS 中观察到的移码突变并确定其作用 DDX41 在正常造血中的作用，我们产生了造血特异性和条件性 Ddx41 缺陷老鼠。我们的初步数据表明，DDX41 缺陷（完全敲除）与 HSPC 功能和造血作用，而 DDX41 杂合性则增加 BM HPSC。此外，通过通过综合蛋白质组学和生化方法，我们在白血病中发现了一种新型 DDX41 相互作用蛋白 SAMHD1，一种 dNTP 酶和宿主防御因子，控制细胞的 dNTP 池。总的来说，我们的初步数据表明DDX41在造血和HSPC功能中具有关键作用。我们假设 DDX41 表达和/或功能的减少会导致无效的造血作用和 MDS 和 AML 的发病机制部分是由于 SAMHD1 活性增加和细胞 dNTP 池改变。因此，本提案的目标是模拟正常和生殖细胞中的体细胞和种系 DDX41 突变。恶性造血，并阐明 HSPC 功能所需的 DDX41 分子功能。通过广泛的造血方法，我们将确定 DDX41 缺陷和 R525H 的作用 MDS 发病率和 AML 进展中的表达（目标 1）。由于 DNMT3A 和 DDX41 突变常见于已进展为 AML 的 MDS 患者，我们将确定 DDX41 是否杂合性或R525H表达与DNMT3A缺陷小鼠结合将导致高危MDS或公开的反洗钱。细胞 dNTP 池减少会损害细胞周期进程并导致基因组不稳定；因此，我们将确定 SAMHD1 活性在 DDX41 缺陷型 HSPC 或突变型 MDS 中的作用，以及细胞 dNTP 库的减少是否会导致基因组不稳定和 AML 的发展（目标 2）。经过阐明 DDX41 恶性造血功能，我们预计会发现新的机制潜在的遗传性和新发MDS。