Regulation of mRNA Translation During Cellular Stress and Apoptosis

基因表达过程在转录、翻译和翻译后等多个水平受到严格调控。在翻译水平上对基因表达的调节允许细胞响应于应激刺激而快速重编程蛋白质输出。在应激条件下，由于关键真核翻译起始因子（eIF）的修饰，整体mRNA翻译（规范翻译）减少。然而，翻译起始的替代手段（非规范翻译）允许产生管理应激条件所需的蛋白质。例如，促存活蛋白和促死亡蛋白的产生通过非经典翻译机制来调节。因此，非规范翻译被认为在细胞应激期间发挥核心作用。我的研究计划的长期目标是了解非经典翻译如何影响细胞稳态和细胞死亡之间的平衡在压力条件下。 内部核糖体进入位点（IRES）介导的翻译是在应激条件下有效的非经典翻译起始机制之一。许多影响细胞死亡的蛋白质的产生受到IRES依赖性机制的调节。大量的证据表明，IRES介导的细胞mRNA翻译在很大程度上依赖于IRES反式作用因子（ITAF）。然而，在应激相关蛋白的表达过程中，细胞IRES和ITAFs的机制还不清楚。在本提案的目标1中，我将研究应激条件下IRES和ITAF介导的细胞mRNA翻译的机制。 上游开放阅读框（uORF）依赖性翻译起始是在应激条件下使用的另一种非经典翻译起始机制。在细胞周期调控和细胞死亡中起关键作用的关键蛋白质受uORF依赖性机制的调控。目前尚不清楚eIFs是否通过调节含uORFs的mRNA的翻译在细胞周期调控和细胞死亡中发挥作用。在目标2中，我将定义一个eIF（eIF5B）的uORF依赖性翻译在细胞周期和细胞死亡中的作用。 我的研究计划将为mRNA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，这项拟议的研究将提供线索，了解各种生理疾病，如癌症和阿尔茨海默氏病中失调的mRNA翻译的相关性。我的研究计划将提供国家的最先进的技能，我的学员在细胞和分子生物学以及生物化学研究领域，并准备他们在学术界，公共部门和不断增长的RNA为基础的行业就业。

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.