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Abstract
The growth of the pancreas, including that of insulin-producing β cells, is dependent on the regulation of protein translation. The eukaryotic translation elongation factor eIF5A, when hypusinated by dexoyhypusine synthase (DHPS), is important for normal protein translation. Inhibition of DHPS impairs translation, growth, and proliferation of pancreatic cells; however, it is unknown if these consequences are due to loss of hypusinated eIF5A (eIF5AHyp) or to the accumulation of unhypusinated eIF5A (eIF5ALys). This dissertation interrogates this question through two main aims. First, DHPS or eIF5A expression is impaired in zebrafish embryos and in the β cells of HFD-fed mice. By comparing the phenotypes of these animals, it is possible to discern whether eIF5ALys has an active role in the inhibited pancreas tissue growth caused by DHPS loss. Second, pathways of eIF5ALys action are investigated by RNA-sequencing, and cell culture is used to detect interactions between eIF5ALys and proteins highlighted by RNA-sequencing. Overall, the data presented support the conclusion that eIF5ALys actively impairs pancreas cell growth by suppressing translation initiation through the integrated stress response kinase GCN2. This is a completely novel finding, as no independent function of eIF5ALys has been documented to date