Publication in PloS Biology: Antagonistic forces induced by RhoA and Cdc42 underlie symmetry breaking and spindle rotation in mouse oocytes.

Antagonistic forces induced by RhoA and Cdc42 underlie symmetry breaking and spindle rotation in mouse oocytes.


To contribute to the formation of an embryo with the correct number of chromosomes, the oocyte must first reduce its genetic makeup by half, to become a haploid gamete. It is during the asymmetric meiotic divisions that the supernumerary chromosomes will be expelled from the oocyte, in two small polar globules. 

The molecular mechanisms of chromosome segregation and polar globule formation are still poorly understood. Using the mouse oocyte as a model, Guillaume Halet's team (IGDR) described an original mechanism of symmetry breaking, by which the meiotic spindle - the cellular structure responsible for the separation of chromosomes - performs a 90° rotation, which is essential for the expulsion of half of the chromosomes into the second polar globule. This unique phenomenon was then conceptualized by numerical simulation in collaboration with the Centuri Institute in Marseille.

This study sheds mechanistic light on the phenomenon of "spindle rotation", first described almost 40 years ago.


Team: Oocyte Dynamics and Implantation in Mammals, IGDR.

27/10/2021