Control of mRNA translation in erythroid cells

In this thesis, we show the role of secondary structures in the 5’UTR of Igbp1 in its translation. We found that the structures had a slight IRES activity. Some ribosomes may be able to bypass (shunt) the Igbp1 5’UTR. Furthermore, during iron deficiency, HRI is activated and phosphorylates eIF2. In this thesis, we investigated genome-wide mRNA translation in response to proteotoxic stress by performing ribosome profiling in erythroblasts. We found an increased ribosome density for 147 transcripts during proteotoxic stress. We found that knockdown of Tis7 yielded 338 differentially expressed. In addition, we treated erythroblasts with Tm for 4 and 8 hours to investigate which targets may be regulated by Tis7 during proteotoxic stress. During Tm treatment, the loss of Tis7 led to differential expression of 33 genes, some of which are components of the translation machinery and some long non-coding RNAs. In addition, also the availability of ribosomes is crucial for erythropoiesis. In this thesis we investigated two cases with mutations in the RPS23 gene. We found that the Arg67Lys mutation impaired yeast growth and led to a reduction in 40S subunits in human cells. The mutation did not affect protein synthesis in human cells. Additionally, the Arg67Lys mutation impaired hydroxylation of a proline residue at position 62. In addition, the Phe120Ile mutation resulted in disruption of a predicted interaction between two phenylalanine residues which led to unstable RPS23. Furthermore, these RPS23 mutations impaired mRNA translation accuracy and exhibited an increased stress granule accumulation during oxidative stress.