MicroRNA genes and their functions

描述(由申请人提供)： MicroRNAs(MiRNAs)是与植物和动物细胞的mRNAs配对的22个核苷酸，主要位于它们的3‘非翻译区(3’UTRs)，指导这些信息的转录后抑制。已经在人类中发现了500多个miRNA基因，由于大多数人类基因都面临着保持与miRNAs配对的选择压力，因此miRNAs已经被证明在哺乳动物发育和人类疾病(包括病毒感染和癌症)中发挥重要作用也就不足为奇了。这项建议侧重于miRNAs的调控靶点和抑制效应，其广泛的、长期的目标是了解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miRNAs放入基因调控网络的能力受到未知miRNAs的限制较少，而更多地受到未知3‘UTRs的限制，特别是在一些细胞中发现的替代3’UTR亚型，而不是在其他细胞中发现的。这一建议的具体目的是：1)鉴定果蝇和脊椎动物的3‘UTRs；2)鉴定影响miRNA靶向特异性的额外的mRNA和细胞特征；3)确定miRNA抑制效应的多样性和时间序列。AIM#1的实验将使用一种新开发的高通量方法来表征苍蝇、斑马鱼和哺乳动物细胞系的3‘UTRs，并了解3’Utr亚型在发育和细胞周期停滞过程中的变化。他们还将在秀丽线虫、苍蝇和脊椎动物中识别长的非编码RNA。Aim#2的实验将确定Poly(A)-尾长、mRNA稳定性和细胞特性对miRNA靶向效果的影响程度。这些结果和目标1的结果将被用来提供更准确和更全面的预测miRNA靶标的列表--这是所有生物学家的资源，对于那些关心真核基因调控、发育和疾病的人来说具有特别的价值。Aim#3的实验将确定从降低的转录水平中可以区分miRNA介导的抑制的程度。他们还将在全球范围内确定靶向的最早可检测到的分子后果。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miRNAs的额外生物学功能，并了解它们的功能障碍如何导致疾病。

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.