A narrow window of cortical tension guides asymmetric spindle positioning in the mouse oocyte

Agathe Chaigne (1) , Clément Campillo (2) , Nir S Gov (3) , Raphaël Voituriez (4) , C. Sykes (5) , Marie-Hélène Verlhac (1) , Marie-Emilie Terret (1)

1 CIRB - Centre interdisciplinaire de recherche en biologie
2 LAMBE - Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement
3 Weizmann Institute of Science [Rehovot, Israël]
4 LPTMC - Laboratoire de Physique Théorique de la Matière Condensée
5 PCC - Physico-Chimie-Curie

Cell mechanics control the outcome of cell division. In mitosis, external forces applied on a stiff cortex direct spindle orientation and morphogenesis. During oocyte meiosis on the contrary, spindle positioning depends on cortex softening. How changes in cortical organization induce cortex softening has not yet been addressed. Furthermore, the range of tension that allows spindle migration remains unknown. Here, using artificial manipulation of mouse oocyte cortex as well as theoretical modelling, we show that cortical tension has to be tightly regulated to allow off-center spindle positioning: a too low or too high cortical tension both lead to unsuccessful spindle migration. We demonstrate that the decrease in cortical tension required for spindle positioning is fine-tuned by a branched F-actin network that triggers the delocalization of myosin-II from the cortex, which sheds new light on the interplay between actin network architecture and cortex tension.

Domaines: Organisation et fonctions cellulaires [q-bio.SC]; Biomécanique [physics.med-ph]

Agathe Chaigne, Clément Campillo, Nir S Gov, Raphaël Voituriez, C. Sykes, et al.. A narrow window of cortical tension guides asymmetric spindle positioning in the mouse oocyte. Nature Communications, 2015, 6 (1), pp.6027/1-10. ⟨10.1038/ncomms7027⟩. ⟨hal-02065107⟩