MicroRNAs in aging

描述(申请人提供)：microRNAs(MiRNAs)是一类新的丰富的小RNA元件，具有调节基因表达的作用。据估计，miRNAs构成了动物基因组中1-4%的基因，它们可能调控多达三分之一的人类基因。此外，最近的一项研究发现，70%-90%的基因组被转录成RNA，其中相当大一部分代表ncRNAs，包括许多未知的miRNAs。然而，大多数miRNAs的作用尚不清楚。我们最近的工作表明，线虫miRNA在长寿中起着重要作用。对线虫的遗传学研究已经确定了无数影响寿命的基因和途径。然而，miRNA参与衰老的程度以及这些基因调节衰老的遗传电路和机制尚未阐明。这项提议将检验以下假设：miRNAs通过作用于衰老途径在寿命中发挥重要作用，以及它们的表达模式提供了新的衰老生物标志物。拟议的研究针对的是一个重要的生物医学研究领域--衰老--在一个肥沃的生物学研究新领域--miRNAs。鉴于miRNAs在不同物种中的高度保守性，这项研究发现的见解很可能与我们对高等生物体衰老的理解有很高的相关性，并可能为治疗人类衰老疾病提供新的诊断和治疗途径。在特定的目标1中，我们将检验额外的已知miRNAs在调节线虫寿命中发挥作用的假设。在这里，我们研究了所有线虫miRNAs的表达模式，并发现在衰老过程中多个miRNAs的表达发生了显着变化。为了研究这些miRNAs在衰老中的作用，我们将表征与衰老相关的顶级miRNA候选基因缺失或过度表达的突变体的寿命。为了了解受年龄相关miRNAs影响的通路，我们将寻找这些miRNAs的靶标。在特定的目标2中，我们将检验新的miRNAs在衰老过程中表达并在寿命调节中发挥作用的假设？虽然已在高等真核生物中鉴定出数千个miRNAs，但很可能还有更多的miRNAs尚未鉴定。在我们的老年线虫克隆筛选(目标1)中，我们获得了近500,000个与已知miRNAs不匹配的小RNA读数。初步的生物信息学分析表明，其中许多序列可能是新的miRNAs。在特定的目标3中，我们将检验miRNA表达模式在决定未来寿命方面提供预测价值的假设。在这里，我们建议将GFP融合到在衰老过程中改变的miRNAs的启动子，并识别其在特定时间或特定组织中表达预测未来寿命的少数miRNAs。

DESCRIPTION (provided by applicant): MicroRNAs (miRNAs) are a novel class of abundant small RNA elements with regulatory roles in gene expression. Estimates are that miRNAs constitute 1-4% of genes in animal genomes and that they may regulate as many as a third of all human genes. In addition, a recent study found that 70-90% of the genome is transcribed into RNA and that a significant percentage of these RNAs represent ncRNAs, including many unidentified miRNAs. However the roles of most miRNAs are unknown. Our recent work demonstrates that a C. elegans miRNA plays a significant role in longevity. Genetic studies in C. elegans have identified myriad genes and pathways that affect longevity. However, the extent of miRNA involvement in aging, and the genetic circuitry and mechanisms by which these genes modulate aging, has not been elucidated. This proposal will test the hypotheses that miRNAs play a fundamental role in life span by acting in aging pathways, and that their expression patterns provide novel biomarkers of aging. The proposed research targets an important biomedical area of research - aging - in the context of a fertile new field of biological research - miRNAs. Given the high conservation of miRNAs across species, it is likely that insights uncovered by this research will have high relevance towards our understanding of aging in higher organisms and may suggest new diagnostic and therapeutic avenues to treat diseases of aging in humans. In Specific Aim 1, we will test the hypothesis that additional known miRNAs function in regulation of C. elegans life span. Here we have examined the expression patterns of all C. elegans miRNAs and have uncovered significant expression changes of multiple miRNAs during aging. To study the role of these miRNAs in aging, we will characterize the life spans of mutants with loss or over-expression of our top aging-associated miRNA candidates. In order to understand the pathways affected by age-related miRNAs, we will search for targets of these miRNAs. In Specific Aim 2, we will test the hypothesis that novel miRNAs are expressed during aging and function in life span regulation? Although thousands of miRNAs have been identified in higher eukaryotes, it is likely that many more remain unidentified. In our cloning screen of aged C. elegans (Aim 1) we obtained nearly 500,000 small RNA reads that do not match known miRNAs. Preliminary bioinformatic analysis suggests many of these sequences may be novel miRNAs. In Specific Aim 3, we will test the hypothesis that miRNA expression patterns provide predictive value in determining future life span. Here, we propose to make GFP fusions to the promoters of miRNAs altered in aging and identify a few miRNAs whose expression at a particular time or in a particular tissue predicts future life span.