Regulation of Aberrant Protein Production

摘要 蛋白质缺陷是由突变、转录错误、压力和其他因素造成的。这些反常现象 蛋白质通常是有毒的，会导致许多人类疾病。有几种质量控制(QC) 细胞中的途径：无义介导的、不停止的和不进行的有缺陷的mRNAs的衰退，以及 已经合成的错误折叠蛋白质的泛素/蛋白酶体系统。最近，我们发现了一个新的QC 被称为异常蛋白产生调节(RAPP)的途径。RAPP是先发制人的QC，它监控 蛋白质在核糖体合成的过程中，感知有缺陷的蛋白质，并降解它们的mRNA模板。 这是第一个将关于异常蛋白质的信息转移到mRNA降解机制的例子。 正常情况下，从核糖体出口通道中出现的新生多肽与靶向或折叠因子相互作用。 当突变阻止了这些相互作用时，RAPP反应中的传感器Ago2蛋白检测到 失去这些重要的相互作用并触发信使核糖核酸降解。令人惊讶的是，Ago2内切酶活性 在这个过程中不是必需的。因此，RAPP的分子机制还不是很清楚，很少有人知道。 了解其信使核糖核酸的降解机制和底物。拟议的项目将在#年填补这些空白 知识。我们的假设是，RAPP是一个一般的蛋白质质量控制途径，由三个 主要步骤：检测异常的新生链状复合体、翻译抑制和形成 降解异常信使核糖核酸的细胞质专化灶。我们的具体目标就是测试这一点 假说，旨在(1)阐明蛋白质表达下调的机制。 以及(2)确定RAPP是否是分泌和分泌蛋白质质量控制的一般机制 哺乳动物细胞中的膜蛋白。该方案涉及体内和体内的综合应用 体外方法，包括我们独特的技术iPINCH，用于鉴定与之相互作用的蛋白质 新生的链条。确定RAPP的范围和机制将对蛋白质质量控制领域产生影响 通过更好地了解针对错误和潜在毒性的细胞防御进行的研究 蛋白质。

ABSTRACT Defective proteins result from mutations, mistakes of transcription, stress, and other factors. These aberrant proteins are often toxic and cause a number of human diseases. There are several quality control (QC) pathways in the cells: nonsense-mediated, no-stop, and no-go decays for defective mRNAs, and the ubiquitin/proteasome system for already synthesized misfolded proteins. Recently, we discovered a new QC pathway called Regulation of Aberrant Protein Production (RAPP). RAPP is a preemptive QC, it monitors proteins during their synthesis at the ribosome, senses defective proteins and degrades their mRNA templates. It is the first example of transferring information about aberrant proteins to mRNA degradation machinery. Normally, nascent polypeptides emerged from the ribosome exit tunnel interact with targeting or folding factors. When a mutation prevents these interactions, the Ago2 protein, a sensor in the RAPP response, detects the loss of these important interactions and triggers mRNA degradation. Surprisingly, Ago2 endonuclease activity is not required in the process. Thus, the molecular mechanism of RAPP is not well understood, very little is known about its mRNA degradation machinery and its substrates. The proposed project will fill these gaps in knowledge. Our hypothesis is that RAPP is a general protein quality control pathway that consists of three major steps: detection of an aberrant nascent chain complex, translational repression, and formation of specialized cytoplasmic foci for degradation of the aberrant mRNA. Our specific aims are designed to test this hypothesis and directed to (1) elucidate the mechanism by which protein expression is down-regulated in RAPP, and (2) determine whether RAPP is a general mechanism of protein quality control for secretory and membrane proteins in mammalian cells. The proposal involves application of comprehensive in vivo and in vitro approaches, including our unique technology, iPINCH, for identification of Proteins Interacting with Nascent Chains. Determining the scope and mechanism of RAPP will impact the field of protein quality control research by providing a better understanding of cellular defense against erroneous and potentially toxic proteins.