Genetic & Molecular Studies of Nematode mRNA Degradation

描述（由申请人提供）：真核mRNA的稳态丰度由其合成和降解的相对速率决定。虽然我们对转录控制的分子机制了解很多，但相比之下，我们对mRNA降解的理解是粗略的。mRNA稳定性是组成型和调控型基因表达的重要控制点。我们将研究C。RNA降解所需的基因。含有提前终止密码子的信使RNA比它们的野生型对应物降解得更快，这种现象称为“无义介导的mRNA衰变”（NMD）或“mRNA监视”。NMD发生在所有测试的真核生物中，并且其作用对人类遗传疾病具有实质性影响。大约三分之一的遗传性疾病是由于无义或移码突变。NMD通过影响突变mRNA的丰度来改变许多疾病表型。疾病严重程度通常反映突变mRNA对NMD的敏感性。影响八个C中任何一个的功能丧失突变。elegans基因（smg-1至smg-8）消除NMD。我们将利用这些突变体研究NMD的遗传和分子特性。我们的工作福尔斯两大类：（1）研究NMD的分子机制;（2）研究NMD在野生型动物中的生物学功能。我们的工作旨在回答两个一般性问题：SMG蛋白与什么相互作用以及它们如何调节mRNA降解？野生型动物的哪些mRNA被NMD降解？我们的方法结合了联合收割机对smg基因及其编码蛋白的遗传、分子和生物化学研究。我们的长期目标是了解mRNA周转的分子机制和NMD的生物学作用。我们的实验有助于这些目标，通过确定所需的NMD的蛋白质，通过描述其在体内的活动，并通过调查NMD在正常生长和发育过程中的作用。

DESCRIPTION (provided by applicant): The steady-state abundance of eukaryotic mRNAs is dictated by the relative rates of their synthesis and degradation. While we know a great deal about molecular mechanisms of transcriptional control, our understanding of mRNA degradation is sketchy by comparison. mRNA stability is an important control point for both constitutive and regulated gene expression. We will investigate C. elegans genes required for mRNA decay. Messenger RNAs that contain premature stop codons are degraded more rapidly than their wild-type counterparts, a phenomenon termed "nonsense-mediated mRNA decay" (NMD) or "mRNA surveillance". NMD occurs in all eukaryotes tested, and its action has a substantial impact on human genetic disease. Approximately one third of inherited diseases are due to nonsense or frameshift mutations. NMD modifies many disease phenotypes by affecting abundance of the mutant mRNA. Disease severity often reflects sensitivity of the mutant mRNA to NMD. Loss-of-function mutations affecting any of eight C. elegans genes (smg-1 through smg-8) eliminate NMD. We will study genetic and molecular properties of NMD using these mutants. Our work falls into two broad categories: (1) investigating the molecular mechanisms of NMD; and (2) investigating the biological function of NMD in wild-type animals. Our work is designed to answer two general questions: With what do the SMG proteins interact and how do they regulate mRNA degradation? What mRNAs of wild-type animals are degraded by NMD? Our methods combine genetic, molecular, and biochemical investigations of smg genes and their encoded proteins. Our long-range goals are to understand the molecular mechanisms of mRNA turnover and the biological roles of NMD. Our experiments contribute to these goals by identifying proteins that are required for NMD, by describing their activities in vivo, and by investigating the role of NMD during normal growth and development.