The role of the aged BM microenvironment in accelerating Dnmt3a mutant clonal hematopoiesis

衰老的BM微环境在加速Dnmt3a突变体克隆造血中的作用

• 批准号: 10472571
• 负责人: Logan Sari Schwartz
• 金额: $ 4.25万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10472571
• 关键词: Adipocytes; Age; Aging; Automobile Driving; Biological Assay; Bone Marrow; Cells; Clonal Expansion; Clonal Hematopoietic Stem Cell; Coculture Techniques; Coronary heart disease; DNA Modification Methylases; DNMT3a; Data; Development; Disease; Elderly; Genes; Goals; Hematologic Neoplasms; Hematological Disease; Hematopoiesis; Hematopoietic; Hematopoietic System; Hematopoietic stem cells; Human Cloning; In Vitro; Incidence; Individual; Inflammatory; Intervention; Ischemic Stroke; Liquid substance; Literature; Maintenance; Molecular; Mus; Mutate; Mutation; Population; Prevention strategy; Risk; Role; Signal Pathway; Signal Transduction; Somatic Mutation; Source; Stromal Cells; Testing; United States; Work; aged; base; bone; bone aging; cell type; cytokine; hematopoietic stem cell expansion; hematopoietic stem cell niche; high risk; human old age (65+); improved; in vivo; mouse model; mutant; new therapeutic target; next generation sequencing; novel; novel strategies; oncostatin M; pressure; prevent; progenitor; response; stem cell function; transcriptome sequencing

PROJECT SUMMARY As we age, we acquire somatic mutations in our hematopoietic stem cells (HSCs), some of which can confer a competitive advantage causing clonal HSC expansion. This clonal expansion is known as clonal hematopoiesis (CH) and is present in 10-15% of individuals aged 70 years or older. Individuals with CH have an increased risk of progression to hematologic malignancy compared to age-matched controls, as well as a higher risk of coronary heart disease and ischemic stroke. While CH can be detected using next-generation sequencing, this information is not sufficient to predict which individuals with CH will develop hematologic malignancy, coronary heart disease, ischemic stroke, or other complications. This prediction is currently not possible due to a lack of understanding of the mechanisms by which clonal HSC expansion and disease development occurs. The long-term goal of my work is to improve understanding of these mechanisms and discover interventions to stop or slow clonal HSC expansion and therefore decrease risk of CH-associated diseases in aging individuals. The novel approach that I am taking is to focus on alterations that occur during aging in context of the bone marrow (BM) microenvironment, which provides critical support for HSC function. To test the concept that CH is aging-associated because of changes occurring in the aged BM microenvironment, I will utilize an inducible mouse model of a hotspot mutation in the gene most frequently mutated in human CH, DNA methyltransferase 3A (DNMT3A). I hypothesize that a major source of selection pressure driving clonal HSC expansion is alterations in the aged BM microenvironment in which HSCs reside. I will test this hypothesis by evaluating the functional impact of changes in the BM microenvironment that have been previously described to occur generally with aging; altered cell type composition and increase in inflammatory cytokines, on expansion of Dnmt3a-mutant (Dnmt3amut) HSCs. I will determine cell type composition and differentiation potential of cells within young and old, Dnmt3amut and wild-type bones to identify cell type(s) and potential mechanisms driving Dnmt3amut HSC expansion in the aged BM microenvironment. Following this, I will functionally evaluate the effects candidate BM microenvironment cell types isolated from aged mice on Dnmt3amut and control HSCs using in vitro co-culture. Additionally, I will identify the cell type(s) in the BM that produce OSM, and perform ex vivo and in vivo studies inducing or inhibiting OSM signaling to assess Dnmt3amut HSC expansion. Successful completion of this project will determine the mechanisms by which, and extent to which, the aged BM microenvironment accelerates development of CH. Targeting these mechanisms has high potential to prevent or reduce clonal hematopoietic burden, and thus reduce incidence of hematologic malignancy, coronary heart disease, and ischemic stroke in aging populations.

项目摘要 随着年龄的增长，我们的造血干细胞（HSC）中会发生体细胞突变，其中一些突变可以赋予造血干细胞（HSC） 竞争优势导致克隆HSC扩增。这种克隆扩张被称为克隆 在某些实施方案中，造血系统疾病（CH）在70岁或更老的个体中存在10-15%。患有CH的人 与年龄匹配的对照组相比，进展为血液学恶性肿瘤的风险增加，以及 冠心病和缺血性中风的风险更高。虽然CH可以使用下一代 测序，该信息不足以预测哪些CH个体将发展血液学 恶性肿瘤、冠心病、缺血性中风或其他并发症。这一预测目前还没有 这可能是由于缺乏对克隆HSC扩增和疾病发生机制的了解， 发展发生。我工作的长期目标是提高对这些机制的理解， 发现干预措施，以阻止或减缓克隆HSC扩增，从而降低CH相关的风险 老年人的疾病。我所采取的新颖方法是关注发生在 在骨髓（BM）微环境的背景下衰老，其为HSC功能提供关键支持。 为了检验CH与衰老相关的概念，因为衰老的BM中发生了变化 微环境中，我将最频繁地利用基因热点突变的诱导型小鼠模型 在人CH中突变，DNA甲基转移酶3A（DNMT 3A）。我假设选择的主要来源 压力驱动克隆HSC扩增是HSC所处的老化BM微环境的改变。我 将通过评估BM微环境变化的功能影响来验证这一假设， 以前描述过通常随着衰老而发生;改变细胞类型组成和增加 炎性细胞因子对Dnmt 3a突变体（Dnmt 3amut）HSC扩增的影响。我会确定细胞类型 年轻和老年、Dnmt 3amut和野生型骨内细胞的组成和分化潜能， 鉴定在老化BM中驱动Dnmt 3amut HSC扩增的细胞类型和潜在机制 微环境在此之后，我将对候选BM微环境细胞的作用进行功能评估， 使用体外共培养从Dnmt 3amut上的老年小鼠和对照HSC中分离的类型。另外，我将 鉴定BM中产生OSM的细胞类型，并进行离体和体内研究， 抑制OSM信号传导以评估Dnmt 3amut HSC扩增。该项目的成功完成将 确定老化BM微环境加速的机制和程度 针对这些机制具有很高的潜力，以防止或减少克隆造血 负担，从而降低血液恶性肿瘤、冠心病和缺血性卒中的发生率， 人口老龄化。