microRNA and Down Syndrome

microRNA 和唐氏综合症

• 批准号: 7740409
• 负责人: TERRY S ELTON
• 金额: $ 20.15万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7740409
• 关键词: 21q; 3' Untranslated Regions; Activities of Daily Living; Address; Adult; Age; Attenuated; Base Pairing; Binding Sites; Bioinformatics; Blood; Brain; Brain region; CREB1 gene; Cell Line; Child; Chromosome abnormality; Chromosomes, Human, Pair 21; Code; Cognitive; Cognitive deficits; Complex; Congenital Abnormality; Congenital Heart Defects; Craniofacial Abnormalities; Data; Defect; Disadvantaged; Down Syndrome; Down-Regulation; Dysplasia; Family; Family health status; Figs - dietary; Future; Gene Expression; Gene Targeting; Genes; Genetic; Healthcare Systems; Heart; Hereditary Disease; Human; Human Chromosomes; Impaired cognition; In Situ Hybridization; Incidence; Individual; Injection of therapeutic agent; Knowledge; Lead; Live Birth; Messenger RNA; Methyl-CpG-Binding Protein 2; MicroRNAs; Molecular; Molecular Profiling; Mus; Mutation; Neoplasms; Neurodegenerative Disorders; Neurodevelopmental Disorder; Neurologic; Neuronal Plasticity; Neuropathogenesis; Pathogenesis; Patients; Penetrance; Perinatal; Phenotype; Play; Population; Proteins; Quality of life; RNA Degradation; Regulation; Regulator Genes; Relative (related person); Repression; Research; Rett Syndrome; Reverse Transcriptase Polymerase Chain Reaction; Role; Secondary to; Site; Specimen; Syndrome; Testing; Therapeutic Intervention; Transcript; Translations; United States; Untranslated Regions; Ventricular; base; care burden; clinically relevant; combinatorial; fetal; gastrointestinal; genetic regulatory protein; human tissue; in vivo; innovation; knock-down; mouse model; neurodevelopment; neuron development; novel; novel therapeutics; protein expression; public health relevance; research study; sex; transcription factor

DESCRIPTION (provided by applicant): The chromosome abnormality in Down syndrome (DS) results from a triplication in a portion of human chromosome 21 (Hsa21), but how this chromosomal anomaly causes the DS phenotype is not clear. The current proposal will directly address this issue, with an emphasis on a novel class of endogenous gene regulators, microRNAs (miRNAs). MiRNAs are generally regarded as negative regulators of gene expression that inhibit translation and/or promote messenger RNA (mRNA) degradation by base-pairing to complementary sequences within protein-coding mRNA transcripts. Our recent bioinformatic analyses established that Hsa21 harbors five miRNA genes. Importantly, miRNA expression profiling, miRNA RT-PCR, and miRNA in situ hybridization experiments demonstrated that all five Hsa21-derived miRNAs are over-expressed in brain and heart specimens from individuals with DS. We now hypothesize that the over-expression of the five Hsa21-derived miRNAs results in the under-expression of a number of important protein targets which contribute, in part, to the DS phenotype. Bioinformatic analyses demonstrated that several thousand proteins may be regulated by these miRNAs. Because combinatorial targeting of multiple miRNAs with a single mRNA may lead to a more pronounced down-regulation relative to mRNAs targeted by a few miRNAs, all of the Hsa21-derived miRNA/mRNA pairs were re-analyzed for the presence of multiple Hsa21-derived miRNA binding sites. This list of candidate targets was subsequently prioritized with respect to the potential clinical relevance of an individual target gene in playing a role in DS. Based on these criteria, we chose to investigate the methyl-CpG-binding protein (MeCP2), a transcription factor, as a potentially important Hsa21- derived miRNA target since its 34-untranslated region harbors at least one putative recognition site for all of the Has21-derived miRNAs. Additionally, MeCP2 is a provocative miRNA target since mutations in this gene contribute to Rett syndrome, a neurodevelopmental disorder that shares some of the neurologic abnormalities observed in DS. Our preliminary data now demonstrate that MeCP2 mRNA is a direct target of Hsa21-derived miR-155 and that MeCP2 is under-expressed in human fetal and adult DS brain specimens and in a mouse model of DS. As a consequence of attenuated MeCP2 expression, transcriptionally-activated and -silenced MeCP2 target genes are aberrantly regulated in these DS brain specimens. To begin to substantiate a causal role of Hsa21-derived miRNAs in DS, in vivo silencing of endogenous mature miR-155 expression by intra- ventricular injection of antagomir-155 resulted in the normalization of miR-155 and MeCP2 expression levels in the DS mouse brains. Taken together, these preliminary data suggest that improper repression of MeCP2, secondary to trisomic over-expression of miR-155, result in the aberrant regulation of MeCP2 target genes. This dysregulation subsequently results in the destabilization of important "regulatory circuits" that contribute, in part, to the cognitive defects that occur in DS individuals. PUBLIC HEALTH RELEVANCE: This project represents a novel line of inquiry regarding the molecular mechanisms of DS. This study will provide "proof of concept" that Hsa21-derived miRNAs inhibit the expression of critical regulatory proteins, which in turn, results in aberrant expression of a number of factors critical for neurodevelopment. Our approach includes a comprehensive and multi-disciplinary approach and includes human tissues, cell lines, and a DS mouse model. Our project will define miRNA/mRNA targets responsible for DS and will potentially lead to novel therapeutic strategies to treat DS individuals in the perinatal period to change the course of pathogenesis.

描述（申请人提供）：唐氏综合症（DS）的染色体异常是由人类21号染色体（Hsa21）部分三倍体引起的，但这种染色体异常如何导致DS表型尚不清楚。当前的提案将直接解决这个问题，重点是一类新型的内源基因调节因子，microRNA (miRNA)。 miRNA 通常被认为是基因表达的负调节因子，通过与蛋白质编码 mRNA 转录物内的互补序列进行碱基配对来抑制翻译和/或促进信使 RNA (mRNA) 降解。我们最近的生物信息分析表明 Hsa21 含有 5 个 miRNA 基因。重要的是，miRNA 表达谱、miRNA RT-PCR 和 miRNA 原位杂交实验表明，所有五种源自 Hsa21 的 miRNA 在 DS 患者的大脑和心脏样本中均过度表达。我们现在假设五个 Hsa21 衍生的 miRNA 的过度表达导致许多重要蛋白质靶标的表达不足，这些蛋白质靶标在一定程度上促成了 DS 表型。生物信息学分析表明，数千种蛋白质可能受到这些 miRNA 的调节。由于多个 miRNA 与单个 mRNA 的组合靶向可能会导致相对于少数 miRNA 靶向的 mRNA 更显着的下调，因此重新分析了所有 Hsa21 衍生的 miRNA/mRNA 对是否存在多个 Hsa21 衍生的 miRNA。 miRNA 结合位点。随后，根据单个靶基因在 DS 中发挥作用的潜在临床相关性，对候选靶点列表进行了优先排序。基于这些标准，我们选择研究甲基 CpG 结合蛋白 (MeCP2)（一种转录因子）作为潜在的重要 Hsa21 衍生 miRNA 靶标，因为它的 34 个非翻译区至少有一个假定的所有转录因子识别位点。 Has21 衍生的 miRNA。此外，MeCP2 是一个令人兴奋的 miRNA 靶标，因为该基因的突变会导致 Rett 综合征，这是一种神经发育障碍，与 DS 中观察到的一些神经系统异常相同。我们的初步数据现在表明，MeCP2 mRNA 是 Hsa21 衍生的 miR-155 的直接靶标，并且 MeCP2 在人类胎儿和成人 DS 脑标本以及 DS 小鼠模型中表达不足。由于 MeCP2 表达减弱，转录激活和沉默的 MeCP2 靶基因在这些 DS 脑标本中受到异常调节。为了开始证实 Hsa21 衍生的 miRNA 在 DS 中的因果作用，通过心室内注射 antagomir-155 体内沉默内源性成熟 miR-155 表达，导致 DS 小鼠中 miR-155 和 MeCP2 表达水平正常化大脑。综上所述，这些初步数据表明，继发于 miR-155 三体过度表达之后，对 MeCP2 的不当抑制会导致 MeCP2 靶基因的异常调节。这种失调随后会导致重要“调节回路”的不稳定，从而在一定程度上导致 DS 个体出现认知缺陷。公共健康相关性：该项目代表了有关 DS 分子机制的新颖探究路线。这项研究将提供“概念证明”，证明 Hsa21 衍生的 miRNA 会抑制关键调节蛋白的表达，进而导致许多对神经发育至关重要的因子的异常表达。我们的方法包括全面的多学科方法，包括人体组织、细胞系和 DS 小鼠模型。我们的项目将定义与 DS 相关的 miRNA/mRNA 靶标，并有可能产生新的治疗策略来治疗围产期 DS 个体，以改变发病机制。