The Regulation of Protein Synthesis by Oxygen

生命的标准之一是有机体对刺激做出反应和适应的能力。我的研究计划集中在蛋白质合成机制方面的这一标准。蛋白质合成也被称为翻译，是遗传信息从信使核糖核酸（mRNA）流向蛋白质的基本生物过程。细胞应激导致翻译工作从维持基本细胞功能转向应激反应蛋白的产生。这通过抑制典型的帽依赖性翻译起始而发生，其通过mRNA的5'帽进入mRNA并占翻译的>95%。我的研究项目解决了细胞生物学中的一个主要问题：当帽依赖性翻译受到抑制时，细胞如何在应激期间将其mRNA翻译成蛋白质？我们专注于人类细胞中的缺氧（低氧），因为充足的氧气获取是生命最重要的适应过程之一，以最大限度地提高细胞能量生产。事实上，2019年诺贝尔生理学或医学奖授予了Kaelin，Ratcliffe和Semenza博士，以表彰他们发现细胞如何感知和适应氧气供应。直到最近，人们认为缺氧细胞在应激期间从典型的帽依赖性翻译（由帽结合eIF4E介导）转换为帽非依赖性过程以翻译选择的mRNA。我们的实验室研究了一种非经典的帽依赖性翻译途径，这是我在博士后研究中发现的，是人类细胞适应缺氧所必需的。该途径利用帽结合蛋白eIF4E2，但仍存在许多问题。该提案的目的是探索低氧可用性如何通过募集专门的翻译因子（Aim 1）和核糖体（Aim 2）产生专门的翻译反应。我们还将研究基因表达如何受到生理氧气的影响，这是人类细胞居住的环境（目的3）。我们将通过免疫沉淀和RNA测序监测DNA和RNA中氧化核苷酸掺入的变化。我们研究计划的长期总体目标是突出翻译装置的可塑性，使人类细胞能够对氧气供应的变化做出反应。我的创新研究计划将继续对自然科学产生影响，通过影响哺乳动物细胞培养实践，包括氧作为一个变量，并更新目前的教科书翻译控制模型。 该计划将为3名博士，2名硕士和15名本科生提供从事前沿科学的机会，重点是解决问题和协作。结合指导和鼓励，这些机会将导致高影响力的出版物和富有想象力的独立科学家的发展，他们将为加拿大学术界，政府和工业界的职业生涯做好充分准备。

One of the criteria for life is the ability of an organism to respond to stimuli and adapt. My research program focuses on this criterion with regard to the protein synthesis machinery. Also known as translation, protein synthesis is a fundamental biological process in the flow of genetic information from messenger ribonucleic acid (mRNA) into protein. Cellular stress leads to a refocusing of translation efforts away from the maintenance of basic cell functions and toward the production of stress response proteins. This occurs by repressing canonical cap-dependent translation initiation, which accesses mRNAs through their 5' cap and accounts for >95% of translation. My research program addresses a major question in cell biology: how do cells translate their mRNAs into protein during periods of stress when cap-dependent translation is repressed? We focus on hypoxia (low oxygen) in human cells because adequate oxygen acquisition has been one of life's most essential adaptive processes to maximize cellular energy production. Indeed, the 2019 Nobel Prize in Physiology or Medicine was awarded to Drs. Kaelin, Ratcliffe, and Semenza for their discoveries of how cells sense and adapt to oxygen availability. Until relatively recently, it was thought that hypoxic cells switch from canonical cap-dependent translation (mediated by the cap-binding eIF4E) to cap-independent processes to translate select mRNAs during stress. Our lab studies a non-canonical cap-dependent translation pathway, discovered during my postdoctoral research, that is required for human cells to adapt to hypoxia. This pathway utilizes the cap-binding protein eIF4E2, but many questions remain. The Aims in this proposal seek to discover how low oxygen availability generates a specialized translation response through the recruitment of specialized translation factors (Aim 1) and ribosomes (Aim 2). We will also investigate how gene expression is influenced by physiological oxygen, which is the environment where human cells reside (Aim 3). We will monitor changes in the incorporation of oxidized nucleotides within DNA and RNA through immunoprecipitation and RNA sequencing. The long-term overarching goal of our research program is to highlight the plasticity of the translation apparatus that allows human cells to respond to changes in oxygen availability. My innovative research program will continue to have impacts on the natural sciences by influencing mammalian cell culture practices to include oxygen as a variable, and update current textbook models of translational control. This program will provide 3 PhD, 2 MSc, and 15 undergraduates with the opportunity to engage in cutting-edge science, with an emphasis on problem solving and collaboration. Combined with guidance and encouragement, these opportunities will lead to high impact publications and the development of imaginative, independent scientists who will be well prepared for careers in Canadian academia, government, and industry.