The role of nonsense-mediated mRNA decay in embryonic stem cell gene expression

描述（由申请人提供）：基因表达是一个复杂的过程，包括细胞的遗传信息从其DNA到mRNA分子，然后到功能蛋白质的顺序转移。特定的RNA监视机制监测这一过程，并负责降解有缺陷的mRNA，以保护细胞不产生异常蛋白质。无义介导的mRNA衰变（NMD）是一种保守的RNA监视途径，其检测并破坏编码提前终止密码子（PTC）的mRNA，从而阻止截短产物的翻译。作为疾病病理学的重要调节剂，NMD途径是目前正在开发的几种治疗策略的靶点。除了靶向异常的mRNA，NMD还调节正常的基因表达，通常通过调节可变剪接的变化。此外，NMD是多种生物体中正常胚胎发育所必需的。尽管有大量的研究，但是，这一过程在细胞内稳态中的作用和控制其活性的机制仍然不完全清楚。本研究采用高通量测序技术结合分子生物学和计算技术研究NMD通路在小鼠胚胎干细胞（mESC）基因表达中的作用。为了实现这一目标，将确定其稳定性和翻译效率受NMD调节的那些mRNA亚型以及决定其对该途径的易感性的mRNA特征。还将确定与国家导弹防御系统途径的重要组成部分Upf1直接相关的信息。这些研究的结果将阐明这种RNA监视途径对基因表达的影响的广度，以及这些影响超出清除异常mRNA分子的程度，这些问题与理解NMD抑制疗法的影响特别相关。此外，这些研究将专门解决的作用，基本的NMD因子，Upf1，在mRNA表达在早期发展，并可能有助于解释的原因，胚胎发育的依赖NMD途径。! 公共卫生相关性：近三分之一的人类遗传疾病与DNA突变有关，这些突变导致基因内产生无义密码子。由于无义介导的mRNA衰变（NMD）途径是无义mRNA稳定性的关键调节剂，因此了解如何以及何时触发该活性与治疗此类疾病的病理学和治疗开发相关。

DESCRIPTION (provided by applicant): Gene expression is a complex process that encompasses the sequential transfer of a cell's genetic information from its DNA into mRNA molecules and then into functional proteins. Specific RNA surveillance mechanisms monitor this process and are responsible for degrading defective mRNAs to protect the cell from producing aberrant proteins. Nonsense-mediated mRNA decay (NMD) is a conserved RNA surveillance pathway that detects and destroys mRNAs encoding premature termination codons (PTCs), thus preventing the translation of truncated products. As an important modulator of disease pathology, the NMD pathway is the target of several therapeutic strategies currently in development. In addition to targeting aberrant mRNAs, NMD also regulates normal gene expression, often via regulated changes in alternative splicing. Furthermore, NMD is required for proper embryonic development in multiple organisms. Despite significant research, however, the role of this process in cellular homeostasis and the mechanisms that govern its activity remain incompletely understood. This proposal uses high-throughput sequencing combined with molecular biological and computational techniques to investigate the role of the NMD pathway in mouse embryonic stem cell (mESC) gene expression. Towards this goal, those mRNA isoforms whose stability and translational efficiency are regulated by NMD and the mRNA features that determine their susceptibility to this pathway will be determined. Messages that directly associate with Upf1, an essential component of the NMD pathway, will also be identified. The results of these studies will illuminate the breadth of the impact that this RNA surveillance pathway has over gene expression and the extent to which these effects extend beyond the clearing of aberrant mRNA molecules, questions particularly relevant to understanding the repercussions of NMD-suppression therapies. Furthermore, these studies will specifically address the role that the essential NMD factor, Upf1, has in mRNA expression in early development and may help to explain the reasons for the dependency of embryogenesis on the NMD pathway. ! PUBLIC HEALTH RELEVANCE: Nearly one third of all human genetic disorders have been linked to DNA mutations that result in the production of nonsense codons within genes. As the nonsense-mediated mRNA decay (NMD) pathway is a key modulator of the stability of nonsense mRNAs, understanding how and when this activity is triggered is relevant to the pathology of and therapeutic development for the treatment of such disorders.