Translational control in echinoderms: the calm before the storm

Starfish oocytes and sea urchin eggs are two different echinoderm model systems that have helped to address the control of gene expression at the translational level in relation to cell cycle regulation. This review describes the different mechanisms that control the translation of cyclin B mRNA during starfish meiotic maturation and sea urchin fertilization. During starfish meiotic maturation, cyclin B translation specifically depends on a CPEB regulation pathway whereas global protein synthesis appears to be regulated by the mTOR pathway. Three translation factors, eIF4F, eIF2α and eEF2, are activated in vivo in response to sea urchin egg fertilization, leading to an increase of protein synthesis. The mTOR signaling pathway involves in 4E-BP degradation and fine-tuning orchestration of cyclin B mRNA translation following fertilization is conserved in two sea urchin species separated by 20 millions years of evolutionary time. Combining biochemical, structural, cellular, and mathematical approaches, the analysis of the spatio-temporal dynamics of protein synthesis activation in different echinoderm model systems should provide insights into essential mRNA translation regulation occurring in physiological conditions.