Nonsense-mediated mRNA decay and beyond

这种MIRA应用扩展了我们数十年来对无义介导的mRNA衰变（NMD）的研究， NMD因子如何在细胞代谢的其他方面发挥作用。NMD是一个基本的生物武器系统， 哺乳动物细胞消除含有无义密码子的mRNA的过程，所述无义密码子来源于遗传或 获得性移码或无义突变。NMD还消除了估计三分之一的mRNA， 由基因转录和/或mRNA产生过程中的常规错误产生。多年来我们 致力于阐明NMD的分子机制。作为众多成果之一，我们建立了一个 临床医生和研究人员用来预测哪些无义密码子会导致遗传性与非遗传性的“规则”。 显性遗传病我们还证明了细胞如何调节NMD作为一种免疫调节剂的效率。 在变化的环境中的适应机制，例如在发育、分化或药物 治疗。该应用程序追求我们的偶然发现，即NMD在脆性X中过度激活 综合征（FXS），这是最常见的单基因原因的智力残疾和自闭症，影响 1/4000男孩和1/6000-8000女孩。我们的目标是通过以下途径了解FXS中缺失的蛋白质是如何发挥作用的： 与其他蛋白质和mRNA的相互作用，以保护这些mRNA免受翻译和衰变。我们还旨在 以破译RNA结合蛋白Staufen防止免疫反应失控的机制。 另一方面，我们长期以来对细胞核中前mRNA剪接的机械连接的兴趣 细胞质中的mRNA翻译和衰变将扩展到包括基因转录和细胞核 mRNA衰变。长期以来，我们一直对原子核的结构动力学和功能着迷， 帽结合异源二聚体CBP 80 − CBP 20，与新生前mRNA的5 '帽共转录结合。 虽然我们过去的兴趣集中在CBP 80-CBP 20在细胞质的先驱轮中的作用， 翻译，在此期间，我们已经表明外显子连接复合物介导的NMD发生，我们的目的是了解 CBP 80-CBP 20在细胞核中的作用。举个例子，我们正在研究一个大师 其产物调节关键细胞过程的基因的转录辅激活因子与 CBP 80-CBP 20，以促进研究不足的RNA聚合酶III的表达， 转录基因在相关的工作中，我们正在研究CBP 80-CBP 20和小- 核帽结合蛋白（NCBP）3。我们的目标是阐明我们的 发现NCBP 3调节来自编码线粒体功能蛋白质的基因的新mRNA， 生物学这些连接将在体外和离体的骨骼肌细胞中进行检查，后者使用小鼠， 这将有助于深入了解许多人类疾病的病因和发病机理， 神经肌肉疾病和心肌病。虽然我们的利益是广泛的，但它们是由目标联系在一起的。 了解健康和疾病的分子机制，重点是RNA代谢。

This MIRA application extends our decades-long research on nonsense-mediated mRNA decay (NMD) and how NMD factors can function in other aspects of cellular metabolism. NMD is a fundamental biological process by which mammalian cells eliminate mRNAs containing a nonsense codon deriving from a genetic or acquired frameshift or nonsense mutation. NMD also eliminates an estimated one-third of mRNAs that cells produce by routine mistakes made during gene transcription and/or mRNA production. Over the years, we have worked to elucidate the molecular mechanism of NMD. As one of many outcomes, we have established a “rule” that clinicians and researchers use to predict which nonsense codons result in recessively inherited vs. dominantly inherited disease. We have also demonstrated how cells regulate the efficiency of NMD as an adaptive mechanism during changing environments, e.g. during development, differentiation, or drug treatments. This application pursues our serendipitous finding that NMD is hyperactivated in fragile X syndrome (FXS), which is the most common single-gene cause of intellectual disability and autism, affecting 1/4000 boys and 1/6000-8000 girls. We aim to understand how the protein that is missing in FXS functions via interactions with other proteins and mRNAs to protect these mRNAs from translation and decay. We also aim to decipher the mechanism by which the RNA-binding protein Staufen prevents a runaway immune response. On another front, our long-time interest in mechanistic connections that span pre-mRNA splicing in the nucleus to mRNA translation and decay in the cytoplasm will be extended to include gene transcription and nuclear mRNA decay. We have long been fascinated by the structural dynamics and functions of the largely nuclear cap-binding heterodimer CBP80−CBP20, which binds co-transcriptionally to the 5'-cap of nascent pre-mRNAs. While our past interests have focused on the role of CBP80−CBP20 in the pioneer round(s) of cytoplasmic translation, during which we have shown exon-junction complex-mediated NMD occurs, we aim to understand roles of CBP80−CBP20 in the nucleus. As one example, we are studying the mechanism by which a master transcriptional co-activator of genes whose products regulate critical cellular processes engages with CBP80−CBP20 so as to promote the expression of an understudied category of RNA polymerase III- transcribed genes. In related work, we are studying connections between CBP80−CBP20 and the little- understood, and so-called, nuclear cap-binding protein (NCBP)3. We aim to elucidate the significance of our finding that NCBP3 regulates newly made mRNAs from genes encoding proteins that function in mitochondrial biology. These connections will be examined in skeletal-muscle cells in vitro and ex vivo, the latter using mice, which should lend insight into the etiology and pathogenesis of many human diseases that include sarcopenia, neuromuscular disorders, and cardiomyopathies. While our interests are broad, they are connected by the goal to understand molecular mechanisms in health and in disease, with a focus on RNA metabolism.