The Regulation of Protein Synthesis by Oxygen

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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.