Actin assembly ruptures the nuclear envelope by prying the lamina away from nuclear pores and nuclear membranes in starfish oocytes
- European Molecular Biology Laboratory (EMBL), Germany
- Max Planck Institute for Biophysical Chemistry, Germany
Abstract
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 showed 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. Here, we address the mechanism of F-actin-driven NE rupture by correlated live-cell, super-resolution and electron microscopy. 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 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 implications in other contexts such as nuclear rupture observed in cancer cells.
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Full resolution EM montages are provided as supplemental files.
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Author details
Funding
Deutsche Forschungsgemeinschaft (SPP 1464)
- Natalia Wesolowska
European Molecular Biology Laboratory
- Natalia Wesolowska
- Pedro Machado
- Celina Geiss
- Hiroshi Kondo
- Masashi Mori
- Peter Lenart
Max Planck Society
- Ivan Avilov
- Peter Lenart
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Wesolowska et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Actin assembly ruptures the nuclear envelope by prying the lamina away from nuclear pores and nuclear membranes in starfish oocytes
eLife 9:e49774.
https://doi.org/10.7554/eLife.49774
