MicroRNA genes and their functions

描述（由申请人提供）： microRNAs（miRNAs）是一类22-nt的RNA，主要在3'非翻译区（3' UTR）与动植物细胞的mRNA配对，指导转录后抑制这些信息。在人类中已经发现了500多个miRNA基因，并且由于大多数人类基因一直处于选择性压力下以维持其与miRNA的配对，因此miRNA已经被证明在哺乳动物发育和人类疾病中发挥重要作用，包括病毒感染和癌症。该提案的重点是miRNA的调控靶点和抑制作用，其广泛的长期目标是了解RNA在调控基因表达中的作用。随着miRNA基因组学的最新进展，将miRNA置于基因调控网络中的能力受到未知miRNA的限制较少，而更多地受到未知3 'UTR的限制，特别是在一些细胞中发现的替代3' UTR同种型，而不是其他细胞。该提议的具体目标是：1）鉴定果蝇和脊椎动物的3 'UTR，2）鉴定影响miRNA靶向特异性的其他mRNA和细胞特征，以及3）确定miRNA抑制效应的多样性和时间序列。目标#1的实验将使用新开发的高通量方法来表征果蝇、斑马鱼和哺乳动物细胞系的3 'UTR，并了解3' UTR同种型在发育和细胞周期停滞期间如何变化。他们还将鉴定秀丽隐杆线虫、苍蝇和脊椎动物中的长非编码RNA。目标#2的实验将确定poly（A）-尾长度、mRNA稳定性和细胞特征影响miRNA靶向功效的程度。这些结果和目标#1的结果将用于提供一个更精确和全面的预测miRNA靶点列表，这是所有生物学家的资源，对那些关注真核基因调控，发育和疾病的人特别有价值。目标#3的实验将确定从降低的转录水平中可以辨别miRNA介导的阻遏的程度。他们还将在全球范围内确定靶向的最早可检测的分子后果。了解每个miRNA抑制哪些基因以及这种抑制的分子后果将有助于确定miRNA的其他生物学功能，并了解它们的功能障碍如何导致疾病。 公共卫生相关性： 该提案的实验重点是称为microRNA的RNA短片段，它可以与细胞的蛋白质合作，以确定单个基因产生多少蛋白质，包括许多与癌症和其他疾病有关的基因。目标是了解如何最好地预测microRNA调控哪些基因，并确定减少每个受调控基因蛋白质输出的一系列分子事件。实现这些目标将揭示为什么microRNA是正常生长和发育所必需的，以及它们的功能障碍如何导致人类疾病。

DESCRIPTION (provided by applicant): MicroRNAs (miRNAs) are 22-nt RNAs that pair to the mRNAs of plant and animal cells, primarily in their 3' untranslated regions (3'UTRs), to direct the posttranscriptional repression o these messages. More than 500 miRNA genes have been identified in humans, and because most human genes have been under selective pressure to maintain their pairing to miRNAs, it is no surprise that miRNAs have already been shown to play important roles in mammalian development and human disease, including viral infection and cancer. This proposal focuses on the regulatory targets and repressive effects of miRNAs, with the broad, long-term objective of understanding the roles of RNA in regulating gene expression. With recent advances in miRNA genomics, the ability to place miRNAs into gene regulatory networks is limited less by unknown miRNAs and more by unknown 3'UTRs, particularly the alternative 3'UTR isoforms found in some cells but not others. The specific aims of this proposal are: 1) to identify 3'UTRs of flies and vertebrates, 2) to identify additional mRNA and cellular features that influence miRNA targeting specificity, and 3) to determine the diversity and temporal sequence of miRNA repressive effects. Experiments of Aim #1 will use a newly developed high-throughput method both to characterize 3'UTRs of flies, zebrafish, and mammalian cell lines and to learn how 3'UTR isoforms change during development and cell-cycle arrest. They will also identify long noncoding RNAs in Caenorhabditis elegans, flies, and vertebrates. Experiments of Aim #2 will determine the degree to which poly(A)-tail length, mRNA stability and cellular features influence the efficacy of miRNA targeting. These results and those of Aim #1 will be used to provide a more precise and comprehensive list of predicted miRNA targets-a resource for all biologists, and of particular value for those concerned with eukaryotic gene regulation, development, and disease. Experiments of Aim #3 will determine the extent to which miRNA-mediated repression can be discerned from reduced transcript levels. They also will determine, on a global scale, the earliest detectable molecular consequences of targeting. Knowing which genes each miRNA represses and the molecular consequences of this repression will be useful for determining additional biological functions of miRNAs and learning how their dysfunction can contribute to disease. PUBLIC HEALTH RELEVANCE: The experiments of this proposal focus on short snippets of RNA called microRNAs, which can collaborate with the proteins of the cell to determine how much protein is produced from individual genes, including many genes implicated in cancer and other diseases. The goals are to learn how best to predict which genes the microRNAs regulate and to determine the series of molecular events that reduces protein output from each regulated gene. Achieving these goals will shed light on why microRNAs are needed for normal growth and development, and how their dysfunction can contribute to human diseases.