Interrogating genome folding trajectories in health and disease

项目摘要 探测和识别我们感知为气味的挥发性化学物质的天文数字 取决于嗅觉中嗅觉受体(OR)基因的单基因和单等位基因表达 神经元(OSN)。OSN特有的染色体间相互作用的复杂网络协调 分布在18个不同物种的&gt；2000或等位基因中只有1个或等位基因转录激活 染色体。沉默或基因之间的基因组相互作用组装异染色质多染色体 保持OR基因转录不活跃的间隔区，而基因间的基因组相互作用 或增强剂导致多染色体增强子中心，激活单一或转录。在这里，我们 建议将单细胞HIC的变体Dip-C与基于病毒的细胞标记技术相结合，以实现 跨OSN分化谱系的基因组折叠中间体的鉴定。这个“摇篮到板条箱” 基因组分析将跟踪单个OSN前体及其条形码后代，从而实现完整的 绘制每个OR等位基因在转录激活过程中的基因组相互作用图。单人 分子DNA FISH实验将补充拟议的基因组研究，提供高分辨率 洞察在发育过程中协调单个或基因选择的基因组编排。最后， 我们试图探索OSN基因组折叠的轨迹是如何在一种 阿尔茨海默病(AD)的人性化模型。嗅觉障碍、嗅觉减退和嗅觉缺失构成了良好的- 阿尔茨海默病的前驱症状已经确定，但这种有趣的联系的分子病因学尚不清楚。 使用AD的人性化模型，我们发现染色体间或间隔区在 神经退行性变的开始，导致OR转录的强烈下调。因此，我们建议 将我们对基因组折叠转变的单细胞询问应用于AD的背景下，并建立 人类OSN中的核结构基线。破译或隔间如何在健康状态下聚集，以及 它们在疾病中是如何被破坏的，可能为AD的新的预后和诊断工具提供基础， 以及用于AD治疗药物体内筛选的分子检测。

Project Summary Detection and identification of the astronomical number of volatile chemicals that we perceive as odors depends upon the monogenic and monoallelic expression of olfactory receptor (OR) genes in olfactory sensory neurons (OSNs). An intricate network of OSN-specific interchromosomal interactions coordinates the transcriptional activation of only 1 OR allele out of >2000 OR alleles distributed across 18 different chromosomes. Genomic interactions between silent OR genes assemble heterochromatic multi-chromosomal compartments that keep OR genes transcriptionally inactive, whereas genomic interactions between intergenic OR enhancers result in a multi-chromosomal enhancer hub that activates singular OR transcription. Here, we propose to combine Dip-C, a variation of single cell HiC, with viral-based cell tagging technologies, towards the identification of genome folding intermediates across OSN differentiation lineages. This “cradle to crate” genomic analysis will follow individual OSN progenitors and their barcoded progeny, allowing a complete cartography of genomic interactions made by every OR allele en route to transcriptional activation. Single molecule DNA FISH experiments will complement the proposed genomic studies, providing high resolution insight to the genomic choreography that orchestrates singular OR gene choice during development. Finally, we seek to explore how the trajectories of OSN genomic folding become altered and eventually disrupted in a humanized model for Alzheimer’s disease (AD). Olfactory dysfunction, hyposmia, and anosmia constitute well- established prodromal symptoms of AD, but the molecular etiology of this intriguing connection is not known. Using a humanized model for AD we discovered that interchromosomal OR compartments dissipate prior to the onset of neurodegeneration, resulting in strong downregulation of OR transcription. Thus, we propose to apply our single cell interrogation of genome folding transition in the context of AD and to establish the baseline of nuclear architecture in human OSNs. Deciphering how OR compartments assemble in health, and how they become disrupted in disease, may provide the basis for novel prognostic and diagnostic tools for AD, and molecular assays for in vivo screening of AD therapeutics.