MAPK/ERK activity is required for the successful progression of mitosis in sea urchin embryos

Odile Mulner-Lorillon (1) , Héloïse Chassé (1) , Julia Morales (1) , Robert Bellé (1) , Patrick Cormier (1)

1 LBI2M - Laboratoire de Biologie Intégrative des Modèles Marins

Using sea urchin embryos, we demonstrate that the MEK/MAPK/ERK cascade is essential for the proper progression of the cell cycle. Activation of a limited fraction of MAPK/ERK is required between S-phase and M-phase. Neither DNA replication nor CDK1 activation are impacted by the inhibition of this small active MAPK/ERK fraction. Nonetheless, the chromatin and spindle organisations are profoundly altered. Early morphological disorders induced by the absence of MAPK/ERK activation are correlated with an important inhibition of global protein synthesis and modification in the cyclin B accumulation profile. After appearance of morphological disorders, there is an increase in the level of the inhibitor of protein synthesis, 4E-BP, and, ultimately, an activation of the spindle checkpoint. Altogether, our results suggest that MAPK/ERK activity is required for the synthesis of (a) protein(s) implicated in an early step of chromatin /microtubule attachment. If this MAPK/ERK-dependent step is not achieved, the cell activates a new checkpoint mechanism, involving the reappearance of 4E-BP that maintains a low level of protein translation, thus saving cellular energy.

Mots clés: MAPK/ERK pathway; embryonic cell division; cell cycle checkpoint

Domaines: Biologie du développement

Odile Mulner-Lorillon, Héloïse Chassé, Julia Morales, Robert Bellé, Patrick Cormier. MAPK/ERK activity is required for the successful progression of mitosis in sea urchin embryos. Developmental Biology, 2017, ⟨10.1016/j.ydbio.2016.11.018⟩. ⟨hal-01409012⟩