Cyclin B Translation Depends on mTOR Activity after Fertilization in Sea Urchin Embryos

Héloïse Chassé (1) , Odile Mulner-Lorillon (1) , Sandrine Boulben (1) , Virginie Glippa (1) , Julia Morales (1) , Patrick Cormier (1)

1 LBI2M - Laboratoire de Biologie Intégrative des Modèles Marins

The cyclin B/CDK1 complex is a key regulator of mitotic entry. Using PP242, a specific ATP-competitive inhibitor of mTOR kinase, we provide evidence that the mTOR signalling pathway controls cyclin B mRNA translation following fertilization in Sphaerechinus granu-laris and Paracentrotus lividus. We show that PP242 inhibits the degradation of the cap-dependent translation repressor 4E-BP (eukaryotic initiation factor 4E-Binding Protein). PP242 inhibits global protein synthesis, delays cyclin B accumulation, cyclin B/CDK1 complex activation and consequently entry into the mitotic phase of the cell cycle triggered by fertilization. PP242 inhibits cyclin B mRNA recruitment into active polysomes triggered by fertilization. An amount of cyclin B mRNA present in active polysomes appears to be insensitive to PP242 treatment. Taken together, our results suggest that, following sea urchin egg fertilization, cyclin B mRNA translation is controlled by two independent mechanisms: a PP242-sensitive and an additional PP242-insentitive mechanism.

Domaines: Sciences du Vivant [q-bio]; Océan, Atmosphère

Héloïse Chassé, Odile Mulner-Lorillon, Sandrine Boulben, Virginie Glippa, Julia Morales, et al.. Cyclin B Translation Depends on mTOR Activity after Fertilization in Sea Urchin Embryos. PLoS ONE, 2016, 11 (3), pp.e0150318. ⟨10.1371/journal.pone.0150318⟩. ⟨hal-01289105⟩