A new mode of mechano-transduction shakes the oocyte nucleus, thereby fine tunes gene expression modulating the developmental potential.

Understanding the mechanism of nucleus positioning and the information conveyed by it constitute important research axes in Developmental and Reproductive Biology. In most species, the position of the oocyte nucleus predefines the axes of the future embryo. In the mouse oocyte, the nucleus is centered by a pressure gradient generated by a cytoplasmic actin meshwork nucleated by Formin 2. The discovery of this centering mechanism allowed to better understanding its biological significance. Centering the nucleus in mouse oocytes involves a novel mechano-transduction process, which promotes agitation of the nucleus and of its content, including chromatin, thereby modulating gene expression. This fine regulation of the maternal RNA stores explains why nucleus centering is predictive of the quality of the female gamete and of its developmental potential after fertilization.