RésuméStem cells are a population of undifferentiated cells characterized by their capacity of selfrenewal and their potential to differentiate into different cell types. Translational regulation is of paramount importance for proteome remodeling during stem cell differentiation, both at the global and transcript-specific levels. Using an efficient in vitro model of hepatogenic differentiation, based on genetically modified iPSCs exposed to a metabolically optimized 20-days differentiation protocol, data based on polysome profiling experiments previously conducted in the lab have shown that a translational regulation occurs during hepatogenic differentiation. In this work, we pursued the characterization of protein synthesis taking place through the differentiation of these iPSCs demonstrating that global translational regulation is a two-step process in which early stimulation of protein synthesis is followed by a global repression of translation. We hypothesize that this translational regulation may involve RNA Binding Proteins (RBPs) that modulate the translational efficiency of specific transcripts. Based on this assumption, we conducted bioinformatics analysis on transcripts that are specifically translationally regulated during the differentiation process to search for enriched RNA motifs described to interact with RBPs. The results, associated with a thorough literature analysis of the potential candidates, highlighted IGF2BP2 and IGF2BP3 as two potential RBP candidates.
Their expression profile throughout the differentiation process has been investigated, showing a progressive up- and down-regulation of IGF2BP2 and IGF2BP3, respectively. To assess IGF2BP2 function in hepatogenic differentiation of iPSCs, we silenced its expression by using siRNAs. Preliminary results obtained by immunofluorescence analysis suggest that the repression of IGF2BP2 expression leads to an alpha-1 antitrypsin (AAT) downregulation. If confirmed, this suggests that hepatogenic differentiation, or at least AAT expression, could depend on IGF2BP2 activity.
|la date de réponse||janv. 2022|
|Superviseur||Patricia Renard (Promoteur)|