Nuclear shape, growth and integrity in the closed mitosis of fission yeast depend on the Ran-GTPase system, the spindle pole body and the endoplasmic reticulum.
The double lipid bilayer of the nuclear envelope (NE) remains intact during closed mitosis. In the fission yeast Schizosaccharomyces pombe, the intranuclear mitotic spindle has envelope-embedded spindle pole bodies (SPB) at its ends. As the spindle elongates and the nucleus divides symmetrically, nuclear volume remains constant but nuclear area rapidly increases by 26%. When Ran-GTPase function is compromised in S. pombe, nuclear division is strikingly asymmetrical and the newly synthesized SPB is preferentially associated with the smaller nucleus, indicative of a Ran-dependent SPB defect that interferes with symmetrical nuclear division. A second defect, which specifically influences the NE, results in breakage of the NE upon spindle elongation. This defect, but not asymmetric nuclear division, is partially rescued by slowing spindle elongation, stimulating endoplasmic reticulum (ER) proliferation or changing conformation of the ER membrane. We propose that redistribution of lipid within the ER-NE network is crucial for mitosis-specific NE changes in both open and closed mitosis.
Gonzalez
Yanira
Y
Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
Meerbrey
Kristen
K
Chong
Jennifer
J
Torii
Yoshihiro
Y
Padte
Neal N
NN
Sazer
Shelley
S
D049069:ATP-Dependent Proteases / Q000378:metabolism; D053144:Cell Nucleus Shape; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D007425:Intracellular Membranes / Q000201:enzymology; D008563:Membrane Lipids / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D008938:Mitosis / Q000502:physiology*; D009154:Mutation; D009685:Nuclear Envelope / Q000201:enzymology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism; D008941:Spindle Apparatus / Q000201:enzymology*; D013696:Temperature; D013997:Time Factors; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D008563:Membrane Lipids; D024101:Mitochondrial Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D049069:ATP-Dependent Proteases; C085155:PIM1 protein, S cerevisiae; D012697:Serine Endopeptidases; D020931:ran GTP-Binding Protein