Created 23/03/2022
23 Mar
2022
09h15

Dr Pascale Crépieux         CNRS (UMR 7247) Tours                   
Dr Stéphane Pyronnet     INSERM (UMR 1037) Toulouse       
Pr Elisabeth Christians     SU (IMEV) Villefranche                    
Dr Dominique Weil          CNRS (UMR 7622) Paris             
Dr Jacek Kubiak                CNRS (UMR 6290) Rennes               
Pr Patrick Cormier            SU (UMR 8227) Roscoff                  

Fine tuning of translation for cell cycle dynamics remains an important topic in cell research. During my thesis, I analyzed the relationships between mRNA translational activity and mitotic cell division using sea urchin embryos. Egg fertilization triggers the activation of the translational machinery, which is required for resuming the first mitotic division, independently of any transcription. A Translational Regulatory Network (TlRN) remains to be identified and characterized upstream of the cell cycle actors.
Seeking mitotic activities that can help visualize spatial dynamics inside isolated eggs, I obtained original data showing the spatial and dynamic activity of the mitotic complex CyclinB/CDK1 and the phosphorylation of histone H3 at threonine 3 (pH3T3) during embryonic mitosis. Then, I analyzed the in vivo role of specific 5’UTR for controlling the mRNA recruitment onto active polysome following fertilization. Finally, I showed that the translation of the mRNA encoding for eIF4B (eukaryotic Initiation Factor 4B) controls the translational activity and dynamics of the first two mitotic divisions induced by fertilization. I propose that eIF4B acts as a positive regulator within the TlRN. These data will allow to study the potential effect of eIF4B acting upstream the spatial dynamics of CDK1 and pH3T3 activities.