April 2, 2014

Nuclear envelope breakdown is far prettier than my own breakdown when I realized that Girl Scout “cookie season” is over. Today’s image is from a paper that describes the importance of SUN proteins in nuclear envelope breakdown.

Early in mitosis, a cell’s nuclear envelope breaks down to allow the attachment of chromosomes to the mitotic spindle. Nuclear envelope breakdown (NEBD) depends on a tearing process, during which microtubules pull the nuclear envelope towards the centrosomes. Turgay and colleagues found that the SUN proteins help to clear membranes from chromatin during NEBD. SUN proteins reside in the inner nuclear membrane and are part of a complex that connects the nucleus to the cytoskeleton. As seen in the images above, simultaneous depletion of both SUN1 and SUN2 (bottom timelapse) delayed removal of the nuclear envelope (green; chromosomes in red), when compared to control (top).  

Turgay, Y., Champion, L., Balazs, C., Held, M., Toso, A., Gerlich, D., Meraldi, P., & Kutay, U. (2014). SUN proteins facilitate the removal of membranes from chromatin during nuclear envelope breakdown The Journal of Cell Biology, 204 (7), 1099-1109 DOI: 10.1083/jcb.201310116