Mechanisms of microRNA turnover in Arabidopsis

 描述(申请人提供)：microRNAs(MiRNAs)是基因表达的序列特异性调节因子，影响各种真核生物的几乎所有生物学过程。MiRNA水平或活性的缺陷与许多疾病有关。生物发生和降解都有助于体内miRNAs的稳定水平。MiRNA生物发生的基本分子框架已经被阐明。相反，尽管在纤毛虫、藻类、植物和动物模型中的研究表明，存在降解miRNAs和相关小RNAs的保守过程，如小干扰RNAs(SiRNAs)和piwi相互作用RNAs(PiRNAs)，但在大多数生物中尚未确定降解小RNAs的酶。因此，miRNA降解的基本框架有待进一步研究。该项目的目标就是建立这样一个框架。该项目利用了PI实验室使用拟南芥模型在miRNA降解领域取得的最新进展。PI的实验室确定了真核生物中负责两个保守的miRNA降解过程的酶，3‘截断和3’尿苷化(在miRNAs上增加了一个短的富含U的尾巴)。这项拟议的研究结合了遗传学、基因组学和生物化学的方法来研究这些酶的活性、相互依赖和协同作用，目的是建立一个一般的miRNA降解框架。PI的实验室还收集了初步证据，表明内源性目标模拟RNA与miRNA周转有关。该项目将研究目标模拟RNA与一般miRNA降解机制之间的相互作用如何导致特定miRNAs的周转。通过阐明miRNA降解的原理，该项目将产生深远的影响。随着越来越多的证据表明在不同的真核生物中miRNA降解的保守分子机制，利用拟南芥模型的拟议研究将建立一个可能适用于包括人类在内的其他真核生物的miRNA降解的一般框架。这些知识将丰富我们对miRNAs影响的各种生物学过程的理解，并增强我们控制miRNA丰度以治疗疾病的能力。MiRNA降解的分子框架也可能适用于siRNAs或piRNAs，它们正在作为赋予动植物表观遗传记忆的试剂出现，从而进一步扩大了这项工作的影响。

 DESCRIPTION (provided by applicant): microRNAs (miRNAs) are sequence-specific regulators of gene expression that impact almost all biological processes in diverse eukaryotes. Defects in miRNA levels or activities are associated with numerous diseases. Both biogenesis and degradation contribute to the steady-state levels of miRNAs in vivo. The basic molecular framework underlying miRNA biogenesis has been elucidated. In contrast, although studies in ciliate, algal, plant, and animal models have implicated the existence of conserved processes that degrade miRNAs and related small RNAs, such as small interfering RNAs (siRNAs) and piwi-interacting RNAs (piRNAs), the enzymes that degrade small RNAs have yet to be identified in most organisms. As such, a basic framework of miRNA degradation awaits further studies. The goal of this project is to establish such a framework. The project capitalizes on recent advances in the area of miRNA degradation made in the PI's laboratory using the Arabidopsis model. The PI's lab identified the enzymes responsible for two conserved miRNA degradation processes in eukaryotes, 3' truncation and 3' uridylation (addition of a short, U-rich tail to miRNAs). The proposed research employs a combination of genetics, genomics, and biochemical approaches to examine the activities, interdependence and concerted actions of these enzymes with the goal of establishing a general framework of miRNA degradation. The PI's lab has also gathered preliminary evidence that implicates endogenous target mimic RNAs in miRNA turnover. The project will examine how the interplay between target mimic RNAs and the general miRNA degradation machinery results in the turnover of specific miRNAs. By elucidating principles governing miRNA degradation, the project will generate far-reaching impacts. As mounting evidence points to conserved molecular mechanisms underlying miRNA degradation in diverse eukaryotes, the proposed studies using the Arabidopsis model, from which two conserved miRNA degradation processes were first described and the enzymes responsible for these processes were first identified, will establish a general framework of miRNA degradation that is likely applicable to other eukaryotes including humans. The knowledge will enrich our understanding of various biological processes that are influenced by miRNAs and enhance our ability to control miRNA abundance to treat diseases. The molecular framework of miRNA degradation is also likely applicable to siRNAs or piRNAs, which are emerging as agents that confer epigenetic memory in plants and animals, thus further broadening the impacts of the work.