Single cell transcriptome profiling of aqueous humor outflow development for discovery of novel childhood glaucoma genes

项目总结/摘要 原发性先天性青光眼（PCG）是一种影响婴儿的破坏性眼部疾病， 对男性的总体性别偏见（1.5：1）。它是由眼内压（IOP）升高引发的， 眼球肿胀，眼球增大，疼痛，严重的组织损伤，常导致失明和眼球摘除， 很大一部分儿童。所有已知的原因都是由于未能正确地发展水状体 流出（AHO）结构对调节液体引流很重要-主要是小梁网（TM） Schlemm氏管（SC）目前已知CYP 1B 1、LTBP 2、TEK和ANGPT 1 4个基因的突变， 在不同人群中导致25%的PCG。CYP 1B 1突变单独占病例的20%， 女性（1：2）。这些已知的基因对于TM和/或SC的发展都是重要的。 迄今为止，外显子组测序工作，其余75%的病例的潜在机制仍未发现 而男性的性连锁基因还有待鉴定。我们假设隐藏在基因中的难以捉摸的基因 PCG对AHO通路的发展至关重要，因此在AHO通路的发展过程中表达，但我们 目前缺乏对这些重要基因形成过程中基因表达的全面了解， 眼结构我们认为，这些重要途径的鉴定将有助于发现 PCG的难以捉摸的分子机制，这反过来将允许治疗的发展 针对潜在的疾病生物学。直到最近，表达谱的可行性， 由于其复杂的结构和细胞类型的多样性，该途径受到限制。单细胞RNA测序 （scRNAseq）技术已经通过基于RNA的不同细胞群的分子分离实现了这样的研究。 在单细胞水平上的表达谱。为了解决我们的中心假设，我们将分析转录组， 从AHO途径内的所有细胞类型中，利用scRNAseq在其整个开发过程中获得。大鼠组织将 因为它们与人类共享AHO的所有主要阶段和形态特征 途径发育，可以繁殖到定义的发育年龄，并将提供显着更大的组织 对比小鼠进行scRNAseq分析。我们将在6时从男性和女性组织中生成单独的数据集 不同年龄（P4、P8、P16、P48、P80和P180），使得能够鉴定差异表达的基因， 特定于每种细胞类型、发育阶段和性别的途径。然后我们将利用这些资源来揭示 来自分子上未解决的PCG的现有外显子组测序数据中可能的致病基因变异 例候选疾病基因在发育中的AHO结构中的表达将通过原位杂交来证实。 杂交（RNAscope）研究。最后，将创建野生型和变异的迷你基因来测试 使用各种基于细胞的测定来确定每个候选致病变异对基因功能的影响。

Project Summary / Abstract Primary congenital glaucoma (PCG) is a devastating eye disorder that affects infants and demonstrates an overall gender bias towards males (1.5:1). It is triggered by elevated intraocular pressure (IOP) which leads to painful enlargement of the eye and severe tissue damage, often resulting in blindness and eye enucleation in a significant proportion of children. All known causes are due to failure to correctly develop the aqueous humor outflow (AHO) structures important for regulation of fluid drainage - primarily the trabecular meshwork (TM) and Schlemm’s canal (SC). Mutations in 4 genes, CYP1B1, LTBP2, TEK, and ANGPT1, are currently known to cause 25% of PCG in diverse populations. CYP1B1 mutations alone account for 20% of cases and effect more females (1:2). These known genes are all important for development of the TM and/or SC. Despite global exome sequencing efforts to date, the mechanisms underlying the remaining 75% cases remain undiscovered and male sex-linked genes have yet to be identified. We hypothesize that the elusive genes underlying PCG are critical for and therefore expressed during the development of the AHO pathway, but we currently lack a comprehensive knowledge of gene expression during the formation of these important ocular structures. We propose that the identification of these vital pathways will enable discovery of the elusive molecular mechanisms of PCG, which in-turn will permit the development of treatments aimed at the underlying disease biology. Until recently, the feasibility of expression profiling the AHO pathway was limited due to its complex architecture and variety of cell types. Now, single-cell RNA sequencing (scRNAseq) technology has enabled such studies by molecular separation of different cell populations based on expression profiles at the single-cell level. To address our central hypothesis, we will profile transcriptomes from all cell types within the AHO pathway throughout of its development utilizing scRNAseq. Rat tissues will be utilized because they share with humans all major stages and morphological characteristics of AHO pathway development, can be bred to defined developmental ages, and will supply significantly larger tissues versus mice for scRNAseq profiling. We will generate separate datasets from male and female tissues at 6 different ages (P4, P8, P16, P48, P80, and P180), enabling identification of differentially expressed genes and pathways specific to each cell type, developmental stage, and gender. We will then use this resource to reveal likely disease-causing gene variants within existing exome sequencing data from molecularly unsolved PCG cases. Candidate disease gene expression within the developing AHO structures will be confirmed by in situ hybridization (RNAscope) studies. Finally, wild-type and variant mini-genes will be created to test the effect of each candidate disease-causing variant on the gene’s function using a variety of cell-based assays.