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PDF, English - main document Download (19MB) | Lizenz: Analyzing the individual contributions of translation initiation factors to shaping the proteome of cancer cells by Bortecen, Toman Deniz underlies the terms of Creative Commons Attribution-NoDerivatives 4.0

Abstract

In living cells, proteins are synthesized through the complex multi-step process process of mRNA translation. The initiation step of translation is believed to be rate limiting step of the process and is subject to diverse regulatory mechanisms. A network of proteins, referred to as (eukaryotic) translation initiation factors (eIF), facilitate the recruitment and activation of the translation machinery to initiate protein synthesis. Individual eIF and protein synthesis in general are frequently deregulated in various human cancers to enable aberrant cellular growth and proliferation. Increasing evidence suggests that individual eIF proteins regulate the translation of specific mRNA and do not simply contribute to protein synthesis globally. Changes in protein synthesis are frequently studied using mRNA sequencing- based approaches, however, direct measurements of newly synthesized proteins can be advantageous. However, the majority of established proteomic methods for analyzing changes in protein synthesis have severe limitations. In this thesis, a new proteomics workflow was developed to simplify and improve the analysis of changes in the newly synthesized proteome across numerous conditions. This workflow was then employed to carry out a systematic analysis of changes in protein synthesis, induced by the depletion of 40 different eIF proteins in a human cancer cell line model. The analysis demonstrated that depletion of different eIF lead to distinct changes in protein synthesis, suggesting that several eIF regulate widespread preferential mRNA translation. Acquired data and findings from the research conducted in this thesis could potentially help to characterize specific signatures of eIF-mediated preferential translation of specific mRNA, which could aid in the development of novel therapeutic strategies. In summary, this thesis describes an optimized proteomics workflow for the analysis of newly synthesized proteins was developed and employed to carry out a systematic analysis of how individual eIF shape the proteome of cancer cells.