title: Physical breakdown of the nuclear envelope is not necessary for breaking its barrier function.
abstract: During mitosis in higher eukaryotic cells, nuclear envelope breakdown (NEBD) occurs and leads to the disassembly of the nuclear membrane and nuclear pore complexes (NPC). This brings about a mixing of nuclear and cytoplasmic macromolecules (open mitosis). On the other hand, in many fungi, mitosis occurs without NEBD (closed mitosis). In a recent study, we reported a novel phenomenon in a closed mitosis organism, Schizosaccharomyces pombe: mixing of nuclear and cytoplasmic proteins occurred in meiosis without breakdown of the nuclear membrane or disassembly of nuclear pore complexes. We designated this event virtual nuclear envelope breakdown (V-NEBD). The key event in V-NEBD is nuclear translocation of Rna1, a RanGAP1 homologue in S. pombe. This leads to collapse of the Ran-GTP gradient across the nuclear envelope (NE) and occurs coincidently with V-NEBD. Thus, the barrier function of the NE can be abated without its physical breakdown through modulation of the Ran-GTP gradient.
authors: Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan.
authors: Haruhiko
authors: H
authors: Asakawa
authors: Yasushi
authors: Y
authors: Hiraoka
authors: Tokuko
authors: T
authors: Haraguchi
mesh_terms: D000818:Animals; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008540:Meiosis / Q000502:physiology*; D008938:Mitosis / Q000502:physiology*; D022022:Nuclear Pore / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D020690:GTPase-Activating Proteins; D009687:Nuclear Proteins; D029702:Schizosaccharomyces pombe Proteins; C499298:rna1 protein, S pombe