Regulation of mRNA Translation During Cellular Stress and Apoptosis

基因表达的过程在不同水平上受到严格调控，包括转录、翻译和翻译后步骤。在翻译水平上对基因表达的调节使细胞能够快速地重新编程蛋白质输出，以响应压力刺激。在应激条件下，由于关键的真核生物翻译起始因子(EIF)的修饰，整体mRNA翻译(规范翻译)减少。然而，另一种翻译启动的方法(非规范翻译)允许产生管理应激条件所需的蛋白质。例如，支持生存和支持死亡的蛋白质的产生都通过非规范的翻译机制进行调节。因此，非正则翻译被认为在细胞应激过程中起着核心作用。我的研究计划的长期目标是了解非规范翻译如何在压力条件下影响细胞动态平衡和细胞死亡之间的平衡。 内部核糖体进入位点(IRES)介导的翻译是应激条件下有效的非规范翻译启动机制之一。许多影响细胞死亡的蛋白质的产生受到IRES依赖的机制的调节。大量证据表明，IRES介导的细胞内mRNAs的翻译在很大程度上依赖于IRES反式作用因子(ITAFs)。然而，细胞内IRESes和ITAFs在应激相关蛋白表达过程中的作用机制尚不清楚。在这个提案的目标1中，我将研究在应激条件下IRES和ITAFs介导的细胞mRNAs翻译的机制。 上游开放阅读框架(UORF)依赖的翻译启动机制是应激条件下的另一种非典范翻译启动机制。在细胞周期调控和细胞死亡中起关键作用的关键蛋白受uORF依赖机制的翻译调控。目前尚不清楚EIF是否通过调节含有uORFs的mRNAs的翻译而在细胞周期调节和细胞死亡中发挥作用。在目标2中，我将定义一个eIF(EIF5B)在细胞周期和细胞死亡中的作用。 我的研究计划将对信使核糖核酸的翻译过程提供重要的见解。所产生的知识将适用于发育、分化和变态的分子生物学研究领域。此外，这项拟议的研究将为理解失调的mRNA翻译与各种生理疾病(如癌症和阿尔茨海默病)的相关性提供线索。我的研究计划将为我的学员提供细胞和分子生物学以及生物化学研究领域的最先进技能，并为他们在学术界、公共部门和不断增长的基于RNA的行业就业做好准备。

The process of gene expression is tightly regulated at various levels including transcriptional, translational and post-translational steps. The regulation of gene expression at the translational level allows cells to rapidly reprogram protein output in response to stress stimuli. During stress conditions, global mRNA translation (canonical translation) is reduced due to modification of key eukaryotic translation initiation factors (eIFs). However, the alternative means of translation initiation (non-canonical translation) allow production of proteins that are required to manage stress conditions. For example, the production of both pro-survival and pro-death proteins is regulated via non-canonical translation mechanisms. Thus, the non-canonical translation is considered to play a central role during cellular stress. The long-term goal of my research program is to understand how non-canonical translation impacts the balance between cellular homeostasis and cell death during stress conditions. Internal ribosome entry site (IRES)-mediated translation is one of the validated non-canonical translation initiation mechanisms that operates under stress conditions. The production of many proteins that affect cell death is regulated by an IRES-dependent mechanism. Extensive evidence suggests that IRES-mediated translation of cellular mRNAs greatly relies on IRES trans-acting factors (ITAFs). However, the mechanisms of cellular IRESes and ITAFs during expression of stress-related proteins are poorly defined. In Objective 1 of this proposal, I will investigate the mechanism of IRES- and ITAFs-mediated translation of cellular mRNAs during stress conditions. Upstream open reading frame (uORF)-dependent translation initiation is another non-canonical translation initiation mechanism used under stress conditions. Key proteins, which play critical roles in cell cycle regulation and cell death, are translationally regulated by the uORF-dependent mechanism. It remains unknown if eIFs play a role in cell cycle regulation and cell death by modulating translation of uORFs-containing mRNAs. In Objective 2, I will define the role of one eIF (eIF5B) for uORF-dependent translation in cell cycle and cell death. My research program will provide significant insight into the process of mRNA translation. The knowledge generated will be applicable to the molecular biology research areas of development, differentiation, and metamorphosis. Moreover, this proposed study will provide clues toward understanding the relevance of dysregulated mRNA translation in various physiological disorders such as cancer, and Alzheimer's disease. My research program will provide state-of-the-art skills to my trainees in cellular and molecular biology as well as biochemistry research areas and prepare them for employment in academia, public sector, and the growing RNA-based industry.