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Marie-Emilie TERRET, Collège de France.

Aberrant cortical tension generates aneuploidy in oocytes through deregulation of myosin-II
When Jan 31, 2020
from 11:00 AM to 12:00 PM
Contact Name Salle des Thèses, Equipe Delattre
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Meiosis in human females is error-prone, generating a high basal rate of aneuploid oocytes. Human and mouse oocytes developmental potential can be predicted by their mechanical properties. Their development into blastocysts requires a specific stiffness window. In this study, we combine live cell and computational imaging, laser ablation and biophysical measurements to investigate how deregulation of cortex tension in the oocyte contributes to early developmental failure. We focus on extra-soft cells, the most common defect in a natural population. Using two independent tools to artificially decrease cortical tension and enrich in this subpopulation, we show that chromosome alignment is impaired in extra-soft mouse oocytes, despite normal spindle morphogenesis and dynamics, inducing aneuploidy. Decrease in the intensity of the forces applied to the chromosomes in extra-soft oocytes does not likely contribute to chromosome misalignment. The main cause is a cytoplasmic increase in myosin-II activity that could sterically hinder chromosome capture. We describe here a new mode of generation of aneuploidies that could be very common in oocytes and could contribute to the high aneuploidy rate observed during female meiosis, a leading cause of infertility and congenital disorders.

Contact : M. Delattre