Cellular and functional impact of SAMD9L mutations on hematopoiesis and myelodysplasia

项目总结： 骨髓增生异常综合征(MDS)的发展是一个多步骤的过程，涉及疾病的起始， 获得协同突变的克隆性进展以及与 微环境。在这份提案中，我们将特别关注这条途径中的最初事件，最终 导致儿童7号染色体丢失和MDS。通过我们最近对儿科MDS的研究，我们 染色体7-SAMD9和SAMD9上两个干扰素诱导基因的种系杂合突变 SAMD9L-在组织培养细胞中外源表达时会导致生长抑制，并 与一系列不同髓系异常的儿童的7号单体相关。奇怪的是，这份复制品 在这些患者中普遍丢失的7号染色体的拷贝是含有突变等位基因的副本。因此，它 在这种情况下，单体7似乎是对这些突变的细胞效应的一种适应，虽然 可能为这些患者的造血细胞生长提供了一种机制，丢失一个拷贝的 7号染色体可导致MDS或其他造血异常。这些基因组和临床发现 为研究SAMD9L突变对细胞和功能的影响建立强有力的科学前提 在人类和小鼠的造血细胞中，他们的长期目标是了解这些突变是如何 最终导致具有单体7的MDS。我们假设突变的SAMD9L的表达减少 造血细胞的生长和分化，以及不同的SAMD9L等位基因可以与细胞协同 影响造血表型的内在或外在因素。我们将使用 在人类和小鼠中使用遗传工具和功能分析的组合来跟踪特定的目标 造血细胞。具体目标1：我们将测试不同SAMD9L突变对原发肿瘤细胞的体外影响 造血细胞。具体目标2：我们将确定Samd9l等位基因对自我更新和 转型。具体目标3：我们将测试环境压力和SAMD9L表达的贡献 对人细胞中造血细胞的生长和分化的影响。黄瓜种系突变的鉴定 SAMD9或SAMD9L在儿童MDS中的应用是儿童髓系领域的重大进步 肿瘤。我们提出的研究将确定突变型和野生型SAMD9L在造血中的作用， 其结果最终将影响这些突变患者的临床处理方式。不仅 这项提案是否会显著增强我们对SAMD9L生物学的了解，但我们将广泛讨论如何 染色体非整倍体可能是对细胞压力的适应性反应，这可能是共同的 不同发育异常或癌症的机制。

PROJECT SUMMARY: The development of a myelodysplastic syndrome (MDS) is a multistep process involving disease initiation, clonal progression with acquisition of cooperating mutations and a complex interplay with the microenvironment. In this proposal, we will focus specifically on the initial event in this pathway that ultimately leads to loss of chromosome 7 and MDS in children. Through our recent studies on pediatric MDS, we identified germline heterozygous mutations in two interferon-inducible genes on chromosome 7-SAMD9 and SAMD9L-that result in growth suppression when exogenously expressed in tissue culture cells and are associated with monosomy 7 in children with a range of different myeloid abnormalities. Curiously, the copy of chromosome 7 that is lost in these patients universally is the copy that harbors the mutant allele. Thus, it appears that in this context, monosomy 7 is an adaptation to the cellular effect of these mutations and while likely providing a mechanism for hematopoietic cells to grow in these patients, the loss of one copy of chromosome 7 can lead to MDS or other hematopoietic abnormalities. These genomic and clinical findings establish a strong scientific premise to investigate the cellular and functional impacts of SAMD9L mutations in human and mouse hematopoietic cells with a long-term goal to understand how these mutations can ultimately lead to MDS with monosomy 7. We hypothesize that expression of mutant SAMD9L decreases hematopoietic cell growth and differentiation, and that different SAMD9L alleles can cooperate with cell intrinsic or extrinsic factors to influence hematopoietic phenotypes. We will test our hypothesis with the following specific aims using a combination of genetic tools and functional assays in human and mouse hematopoietic cells. Specific Aim 1: We will test the in vitro impact of different SAMD9L mutations in primary hematopoietic cells. Specific Aim 2: We will determine the effect of Samd9l alleles on self-renewal and transformation. Specific Aim 3: We will test the contribution of environmental stress and SAMD9L expression on hematopoietic cell growth and differentiation in human cells. The identification of germline mutations in SAMD9 or SAMD9L in children with MDS is a significant advancement in the field of pediatric myeloid neoplasms. Our proposed studies will define the role of both mutant and wild-type SAMD9L in hematopoiesis, the results of which will ultimately impact how patients with these mutations are clinically managed. Not only will this proposal significantly enhance our knowledge of SAMD9L biology, but we will broadly address how chromosomal aneuploidy can be an adaptive response to cellular stresses, which is likely a shared mechanism across different developmental abnormalities or cancers.