Author/Editor		Castagnetti, Stefania; Božič, Bojan; Svetina, Saša
Title		Mechanical and molecular basis for the symmetrical division of the fission yeast nuclear envelope
Type		članek
Vol. and No.		Letnik 17, št. 24
Publication year		2015
Volume		str. 15629-15636
ISSN		1463-9084 - Physical chemistry chemical physics : PCCP
Language		eng
Abstract		In fission yeast Schizosaccharomyces pombe, the nuclear envelope remains intact throughout mitosis and undergoes a series of symmetrical morphological changes when the spindle pole bodies (SPBs), embedded in the nuclear envelope, are pushed apart by elongating spindle microtubules. These symmetrical membrane shape transformations do not correspond to the shape behavior of an analogous system based on lipid vesicles. Here we report that the symmetry of the dividing fission yeast nucleus is ensured by SPB-chromosome attachments, as loss of kinetochore clustering in the vicinity of SPBs results in the formation of abnormal asymmetric shapes with long membrane tethers. We integrated these findings in a biophysical model, which explains the symmetry of the nuclear shapes on the basis of forces exerted by chromosomes clustered at SPBs on the extending nuclear envelope. Based on this analysis we conclude that the fission yeast nuclear envelope exhibits the same mechanical properties as simple lipid vesicles, but interactions with other cellular components, such as chromosomes, influence the nuclear shape during mitosis, allowing the formation of otherwise energetically unfavorable symmetrical dumbbell structures upon spindle elongation. The model allows us to explain the appearance of abnormal asymmetric shapes in fission yeast mutants with mis-segregated chromosomes as well as with altered nuclear membrane composition.
Keywords		nuclear envelope symmetrical division fission yeast jedrna ovojnica simetrična delitev fisija kvasovk