Post-transcriptional control of cellular stress responses

所有的有机体都暴露在各种各样的环境压力下，这些压力对它们的生存构成了挑战。压力可能包括热、冷、污染物、辐射、氧自由基和香烟烟雾中的化学物质，仅举几例。这些药物可以引发各种细胞应激反应，帮助细胞应对细胞生理的变化。其中比较著名的应激途径是P53肿瘤抑制途径。P53蛋白是一种转录因子，在许多压力下被激活，包括上面列出的大多数压力。一般来说，转录因子帮助控制哪些基因在任何给定的时间被打开或关闭。激活的p53控制着几个编码蛋白质的基因，这些蛋白质参与了一种称为细胞凋亡的细胞死亡形式，这种形式有助于消除高度受损的细胞。然而，对细胞压力的过度反应可能是有害的，因为它会杀死健康的细胞，损害健康的组织。事实上，人们已经知道，在小鼠模型中，过度活跃的P53版本会加速衰老。因此，当P53转录因子完成其工作时，关闭它与能够打开它一样重要。近年来，我的研究项目一直专注于在一定的压力下如何关闭和控制p53的反应。我们已经发现，P53的反应被设计成能够快速地开启和关闭，这涉及到信使RNA(MRNAs)的调节，因此被称为基因表达的转录后调节。有各种转录后调控步骤来控制mRNAs的命运，包括前mRNA剪接、选择性多聚腺苷基化和microRNA介导的基因沉默，所有这些都构成了这一提议的一部分。此外，我们最近发现的证据表明，另一个众所周知的应激反应是由银杏叶中的一种天然化学物质激活的，这种化学物质干扰了前mRNA剪接的过程。我们的工作表明，这种应激途径(未折叠蛋白反应)是由异常蛋白的产生启动的，最终导致三种不同的转录因子(XBP1、ATF3和ATF6)的激活。我们建议破译前mRNA剪接缺陷和未折叠蛋白质反应之间的联系。在本提案中，我们将使用该领域最前沿的各种技术，包括下一代测序、异源报告构建和CRISPR介导的基因编辑，以解决使用p53反应和未折叠蛋白反应进行基因调控的基本问题，以更好地了解转录后调控过程在维持体内平衡中的作用。

All organisms are exposed to a variety of environmental stresses that pose a challenge to their survival. Stresses could include heat, cold, pollutants, radiation, oxygen radicals and chemicals in cigarette smoke, to name a few. These agents can elicit a variety of cellular stress responses that help cells deal with changes in cell physiology. Among the more renowned stress pathways is the p53 tumour suppressor pathway. The p53 protein is a transcription factor that is activated in response to many stresses, including most of those listed above. In general, transcription factors help control what genes are turned on or off at any given time. Activated p53 controls several genes that encode proteins involved in a form of cell death called apoptosis that helps eliminate highly damaged cells. However, over-reacting to cellular stresses could be detrimental by killing healthy cells, damaging healthy tissue. In fact, it is known that hyperactive versions of p53 accelerate aging in mouse models. Therefore, turning off the p53 transcription factor when its job is done is just as important as being able to turn it on. In recent years, my research program has been focussed on how the p53 response is shut off and controlled after a defined stress. We have found that the p53 response is designed to be able to turn on and off rapidly and that this involves the regulation of messenger RNAs (mRNAs) after they are made and is thus referred to as post-transcriptional regulation of gene expression. There are a variety of post-transcriptional regulatory steps that control the fate of mRNAs, including pre-mRNA splicing, alternative polyadenylation and microRNA-mediated gene silencing that all form a part of this proposal. In addition, we recently uncovered evidence that another well-known stress response is activated by a natural chemical from Ginkgo biloba leaves that interferes with the process of pre-mRNA splicing. Our work suggests that this stress pathway (the unfolded protein response) is initiated by the production of aberrant proteins and ultimately leads to the activation of three different transcription factors (XBP1, ATF3 and ATF6). We are proposing to decipher the link between pre-mRNA splicing defects and the unfolded protein response. In the present proposal, we will use a variety of technologies at the forefront of our field, including next generation sequencing, heterologous reporter constructs and CRISPR-mediated gene editing to address fundamental questions in gene regulation using the p53 response and the unfolded protein response to better understand the roles of post-transcriptional regulatory processes in maintaining homeostasis.