Actin mediates nuclear envelope rupture in oocytes
Dr Peter LENART
MPI for Biophysical chemistry, Germany
Friday, January 31st 2020 - 11 a.m.
- Auditorium, IGBMC
Hosted by Development and stem cells, Anne-Cécile REYMANN
The nucleus of oocytes (germinal vesicle) is unusually large and its nuclear envelope (NE) is densely packed with nuclear pore complexes (NPCs) stockpiled for embryonic development. We show that breakdown of this specialized NE is mediated by an Arp2/3-nucleated F-actin ‘shell’ in starfish oocytes, in contrast to microtubule-driven tearing in mammalian fibroblasts. We show that actin is nucleated within the lamina sprouting filopodia-like spikes towards the nuclear membranes. These F-actin spikes protrude pore-free nuclear membranes, whereas the adjoining membrane stretches accumulate packed NPCs associated with the still-intact lamina. Packed NPCs sort into a distinct membrane network, while breaks appear in ER-like, pore-free regions. Thereby, we reveal a new function for actin-mediated membrane shaping in nuclear rupture that is likely to have broad relevance in diverse other contexts such as nuclear rupture frequently observed in cancer cells.