Nonsense-mediated mRNA decay and beyond

这一Mira应用扩展了我们数十年来对无意义介导的mRNA衰变(NMD)的研究，并 NMD因子如何在细胞新陈代谢的其他方面发挥作用。国家导弹防御系统是一种基本的生物学 哺乳动物细胞消除含有无义密码子的mRNAs的过程，该密码子来源于基因或基因 获得性移码或无义突变。NMD还消除了大约三分之一的细胞内的mRNAs 由基因转录和/或信使核糖核酸生产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，我们已经建立了一个 临床医生和研究人员用来预测哪些无用密码子会导致隐性遗传的规则。 主要是遗传性疾病。我们还演示了细胞如何调节NMD作为一种 环境变化期间的适应机制，例如在发育、分化或药物期间 治疗。这个应用程序继续我们的偶然发现，在脆性X中NMD被过度激活 综合征(FXS)，这是导致智力残疾和自闭症的最常见单基因原因，影响 4000个男孩中有1个，6000-8000个女孩中有1个。我们的目标是了解FXS中缺失的蛋白质是如何通过 与其他蛋白质和mRNAs的相互作用，以保护这些mRNAs免受翻译和衰退。我们还瞄准了 为了破译RNA结合蛋白Staufen阻止失控免疫反应的机制。 另一方面，我们长期以来对跨越细胞核内前信使核糖核酸剪接的机械连接感兴趣 在细胞质中的翻译和衰变将扩展到包括基因转录和核 信使核糖核酸衰变。长期以来，我们一直对以核能为主的核燃料的结构动力学和功能着迷 帽结合异二聚体CBP80−CBP20，它与新生前mRNAs的5‘-帽转录结合。 虽然我们过去的兴趣集中在Cbp80−Cbp20在细胞质先锋回合(S)中的作用 翻译，在这个过程中，我们已经证明了外显子连接复合体介导的NMD的发生，我们的目的是理解 Cp80−Cp20在细胞核中的作用。作为一个例子，我们正在研究一位大师 其产物调节关键细胞过程的基因转录共激活因子与 以促进一类未被研究的−聚合酶III- 转录的基因。在相关工作中，我们正在研究Cp80−Cp20与小- 被理解并被称为核帽结合蛋白(NCBP)3。我们的目的是阐明我们的 发现NCBP3从编码线粒体功能的蛋白质的基因中调节新生成的mRNAs 生物学。这些连接将在体外和体外的骨骼肌细胞中进行检测，后者使用小鼠， 这应该有助于深入了解包括石棺减少症在内的许多人类疾病的病因和发病机制， 神经肌肉疾病和心肌病。虽然我们的利益是广泛的，但它们通过目标联系在一起 了解健康和疾病中的分子机制，重点是RNA新陈代谢。

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.