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：
10461039
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/10461039
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.

项目摘要骨髓增生综合征（MDS）是由造血茎/祖细胞受损引起的遗传疾病细胞（HSPC），可以转化为急性髓样白血病（AML）。 MD通常发生在衰老中但是，人口，MDS也可能是由于年轻人的遗传种系突变而表现出来的。死亡/H-box解旋酶基因DDX41中的突变是与继承的MD。遗传的DDX41突变是杂合的，通常是移料器，表明这些突变导致DDX41功能的丧失。在从头MDS中也观察到DDX41突变，并且 AML，通常是错义突变，通常导致氨基酸取代R525H。 DDX41是水解ATP的RNA解旋酶，可以作为先天免疫传感器，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对MDS/AML仍然未知。因此，提出的项目将定义DDX41突变在 MDS/AML的发病机理。模仿在人MD中观察到的移码突变，并确定作用 DDX41在正常造血中，我们产生了造血特异性和条件DDX41缺陷型老鼠。我们的初步数据表明，DDX41缺陷（完全淘汰）与 HSPC功能和造血作用，而DDX41杂合性增加了BM HPSC。另外，通过综合蛋白质组学和生化方法我们鉴定了一种新型的DDX41相互作用蛋白细胞，SAMHD1，一种DNTPase和宿主防御因子，它控制DNTP的细胞池。总体而言，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的表达和/或功能降低了无效的造血和/或功能 MDS和AML的发病机理，部分是由于SAMHD1活性增加和细胞DNTP池的改变。因此，该提案的目标是在正常和恶性造血，并阐明HSPC功能所需的DDX41的分子功能。通过广泛的造血方法，我们将定义DDX41缺陷和R525H的作用 MDS的发病率和向AML的表达（AIM 1）。由于DNMT3A和DDX41突变在已经发展为AML的MDS患者中，通常共同发生，我们将确定DDX41是否杂合性或R525H表达与DNMT3A缺乏小鼠结合将导致高危MD或公开AML。降低的细胞DNTP池会损害细胞周期的进展，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或突变体MD中的作用，以及细胞DNTPS池减少是否导致基因组不稳定性和AML的发育（AIM 2）。经过阐明DDX41恶性造血的功能，我们预计会发现新的机制基本的继承和从头启用。