title: The carboxy-terminus of Alp4 alters microtubule dynamics to induce oscillatory nuclear movement led by the spindle pole body in Schizosaccharomyces pombe.
abstract: Alp4 is an essential component of the S. pombe gamma-tubulin complex. Overproduction of the carboxy-terminus of Alp4 induces oscillatory nuclear movement led by the spindle pole body (SPB). The movement is not dependent on cytoplasmic dynein dhc1, or kinesin-related proteins pkl1 and klp2. Rates of SPB movement correlate with elongation rates of microtubules (MTs) extending backwards from the moving SPB (backward-extending MTs), showing that pushing forces exerted by backward-extending MTs move the nucleus via the SPB. These backward-extending MTs are more stable than those of control cells and, thus, are able to push the SPB further towards the cell end, inducing nuclear oscillation with larger amplitudes than in control cells. SPB movement is biased towards the new end of the cell where levels of the CLIP170 homolog Tip1 increase, suggesting that the movement is related to MT-mediated cell polarity control. These results demonstrate that the carboxy-terminus of Alp4 alters MT dynamics and induces nuclear oscillation by modulating a nuclear positioning mechanism based on the balance of MT pushing forces, and suggest that regulation of gamma-tubulin complex activity is important for controlling MT dynamics and nuclear positioning.
authors.affiliation: Cell Biology Group and CREST/JST, Kansai Advanced Research Center, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan. hmasuda@nict.go.jp
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Masuda
authors.forename: Rumi
authors.initials: R
authors.lastname: Miyamoto
authors.forename: Tokuko
authors.initials: T
authors.lastname: Haraguchi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hiraoka
mesh_terms: D001683:Biological Clocks / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000502:physiology; D002467:Cell Nucleus / Q000502:physiology*; D016764:Cell Polarity / Q000502:physiology; D002478:Cells, Cultured; D002503:Centromere / Q000502:physiology; D006360:Heat-Shock Proteins / Q000502:physiology; D007381:Intermediate Filament Proteins / Q000502:physiology; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000502:physiology*; D008870:Microtubules / Q000502:physiology*; D019913:Nuclear Localization Signals / Q000502:physiology; D009687:Nuclear Proteins / Q000502:physiology; D009991:Oscillometry; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D012568:Schizosaccharomyces / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins / Q000096:biosynthesis / Q000502:physiology*; D008941:Spindle Apparatus / Q000502:physiology*; D016615:Telomere / Q000502:physiology; D014404:Tubulin / Q000502:physiology
chemical_list: C512340:Alp4 protein, S pombe; D018797:Cell Cycle Proteins; D006360:Heat-Shock Proteins; D007381:Intermediate Filament Proteins; D008869:Microtubule-Associated Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D029702:Schizosaccharomyces pombe Proteins; D014404:Tubulin; C114142:tip1 protein, S pombe; C068689:wee1 protein, S pombe; D011505:Protein-Tyrosine Kinases