A mosaic Down syndrome model system comparing isogenic trisomic/disomic cells to unmask trisomy-21 related genomic, epigenomic, and senescence changes acquired across the lifespan

项目总结 唐氏综合症(DS)也与多种共同发生的健康和行为状况有关 早熟(或加速)衰老。最近的临床研究结果提供了一幅更清晰的图景 儿童期、青春期和成年期发育障碍患者的健康结局；然而，人们对此知之甚少 与21三体相关的生物变化的级联，最终导致共发生 条件。胞质DNA作为体细胞获得性变化的“整合因子”的最新发现 为鉴定与年龄和21三体相关的生物改变提供了新的研究方向。细胞可以 通过形成微核(MN)和染色体外端粒环(T环)获得胞质DNA。一个 这种细胞质自身DNA的子集被先天性免疫监视途径识别，这反过来又导致 衰老程度的增加。我们假设21三体增加了MN水平和端粒磨损， 导致衰老和甲基化改变的永久化循环，从而积累/增加频率 随着年龄的增长。发现21三体特异性改变的一种有效方法是评估生物学属性 来自21三体嵌合体(MDS)嵌合体的细胞。人们可以揭开并量化由21三体引起的 通过将等基因二体细胞中观察到的值与三体细胞中存在的值相减去而发生的变化(从而 消除由于总背景遗传构成以及环境影响而产生的混杂效应)。 因此，为了确定21三体不平衡对胞浆dna通路的影响，我们将纵向比较 65名MDS患者在3个时间点上的等基因三体与二体细胞的生物学指标， (包括基线数据，以及长达30年的跟踪调查)。为了检验我们的研究假设，我们将 定量：(1)通过MN检测胞浆中的自身DNA；(2)亚端粒/端粒改变或功能障碍；(3) 衰老模式和细胞因子水平；(4)DNA甲基化模式。这些生物因素中的每一个都会 使用我们开发/优化的“最先进”工具进行分析，其中包括：染色体特异性分析 新的端粒/亚端粒长度分析[Q-FISH和纳米映射]；端粒 功能障碍分析.衰老、转录组和细胞因子标记分析.DNA全基因组研究 甲基化；以及生物信息学建模。我们还将收集/评估深层表型数据。通过审问 生物学指标与表型性状之间的关系，我们将发现它们在 调解健康结果。总之，这种对等基因三体/二体细胞的纵向研究将使我们能够 揭示生物级联中与21三体相关的变化，并将提供对 胞质DNA在DS/MDS相关健康状况中的作用。通过确定驱动程序/中介者关系 在生物标记物之间，我们将创建新的算法，帮助医生识别 DS/MDS患者年龄较早。重要的是，我们将确定新的治疗靶点，这些靶点可以改变我们的 开发治疗方法，以缓解MDS/DS患者获得的健康状况症状。

PROJECT SUMMARY Down syndrome (Ds) has been associated with multiple, co-occurring health and behavioral conditions, as well as precocious (or accelerated) aging. The results of recent clinical studies are providing a clearer picture of health outcomes in childhood, adolescence, and early adulthood in people with Ds; yet very little is known about the cascade of trisomy 21-related biological changes that arise to culminate in the development of co-occurring conditions. The recent discovery of cytosolic DNA as an “integrator” of changes acquired in somatic cells provides a new research direction for identifying age- and trisomy 21-related biological alterations. Cells can acquire cytosolic DNA via micronuclei (MN) formation and extrachromosomal telomere circles (t-circles). A subset of this cytoplasmic self-DNA is recognized by innate immune surveillance pathways, which, in turn, lead to increased levels of senescence. We hypothesize that trisomy 21 increases MN levels and telomere attrition, leading to a perpetuating cycle of senescence and methylation alterations that accumulate/increase in frequency with age. One powerful approach for discovering trisomy 21-specific alterations is to evaluate biological attributes in cells from people with mosaicism for trisomy 21 (mDs). One can unmask and quantify trisomy 21-induced changes by “subtracting” values observed in isogenic disomic cells from those present in trisomic cells (thereby removing the confounding effects due to total background genetic make-up, as well as environmental influences). Thus, to identify the impact of a trisomy 21 imbalance on cytosolic DNA pathways, we will longitudinally compare biological measures in isogenic trisomic versus disomic cells from 65 people with mDs over 3 time points, (including baseline data, and spanning as much as 30 years of follow-up). To test our study hypothesis, we will quantify: (1) cytosolic self-DNA via a MN assay; (2) subtelomere/telomere alterations or dysfunction; (3) senescence patterns and cytokine levels; and (4) DNA methylation patterns. Each of these biological factors will be analyzed with “state of the art” tools we developed/optimized, which include: chromosome-specific assays for MN [SKY/FISH MN assay]); novel telomere/subtelomere length assays [Q-FISH & nanomapping]; telomere dysfunction assays; senescence, transcriptome, and cytokine marker assays; genome-wide studies for DNA methylation; and bioinformatic modeling. We will also collect/evaluate deep phenotype data. By interrogating relationships among and between biological measures with phenotypic traits, we will discover their role in mediating health outcomes. In summary, this longitudinal study of isogenic trisomic/disomic cells will enable us to “unmask” trisomy 21-associated changes in biological cascades and will provide the first assessment of the role of cytosolic DNA in health conditions associated with Ds/mDs. By identifying driver/mediator relationships between biomarkers, we will create new algorithms that will help physicians recognize health conditions at an earlier age in people with Ds/mDs. Importantly, we will identify new therapeutic targets that could transform our approach for developing treatments to alleviate symptoms of health conditions acquired by people with mDs/Ds.