The Control of Gene Expression by Eukaryotic Ribonucleases

项目总结/摘要 RNA降解在基因表达调控中起着重要的作用。它 不仅调节全球转录本丰度， 消除处理不当或定位错误的转录本的机制，或 含有过早翻译终止密码子（PTC）。在我们的实验室工作 专注于真核细胞中两种主要的RNA降解途径：无意义- 介导的衰变（NMD），其降解含PTC的转录物，和外泌体， 它处理各种非编码RNA，并在转录过程中降解转录物。 质量控制过程。基因组学方法和经典遗传学方法的结合 生物化学分析使我们能够确定这些途径的新作用， 基因调控，包括剪接位点选择的校对，特异性 mRNA和Pol.II终止的不同模式下的机制。我们有 还确定了外泌体亚单位临床突变的分子后果， 脑桥小脑发育不全（PCH）。本申请中提出的工作 将广泛扩展我们对外泌体亚基和外泌体蛋白的作用的理解。 其相关因素对RNA加工和降解全基因组。另外我们 将决定外泌体的活动在压力下是如何被控制的，以及它是如何 与其他RNA质量控制途径合作，例如与 翻译.最后，我们将描述促进3 ′-末端形成的机制 对于一类新的mRNAs，它使用一种完全独立于 经典的裂解和多聚腺苷酸化途径。总体而言，拟议的研究将 提供了我们对真核生物参与机制的理解的重大进展， 转录后调节和RNA加工。

Project Summary/Abstract RNA degradation plays multiple essential functions in the control of gene expression. It not only regulates global transcript abundance, but also provides quality control mechanisms to eliminate improperly processed or mis-localized transcripts, or those containing premature translation termination codons (PTCs). Work in our laboratory focuses on two major RNA degradation pathways in eukaryotic cells: Nonsense- Mediated Decay (NMD), which degrades PTC-containing transcripts, and the Exosome, which processes a variety of non-coding RNAs and also degrades transcripts during quality-control processes. A combination of genomic approaches and classical genetic and biochemical analyses has allowed us to identify new roles for these pathways in gene regulation, including proofreading of splice site selection, regulation of specific mRNAs and the mechanisms underlying distinct modes of Pol.II termination. We have also identified the molecular consequences of clinical mutations in exosome subunits implicated in pontocerebellar hypoplasia (PCH). The work proposed in this application will broadly expand our understanding of the role of the subunits of the exosome and of its associated factors on RNA processing and degradation genome-wide. In addition, we will determine how the activity of the exosome is controlled during stress, and how it cooperates with other RNA quality control pathways such as those coupled to translation. Finally we will characterize the mechanisms that promote 3´-end formation for a novel class of mRNAs, which use a mechanism completely independent from the classical cleavage and polyadenylation pathway. Overall, the proposed studies will provide major advances in our understanding of the mechanisms involved in eukaryotic post-transcriptional regulations and RNA processing.