title: Mechanism controlling perpendicular alignment of the spindle to the axis of cell division in fission yeast.
abstract: In animal cells, the mitotic spindle is aligned perpendicular to the axis of cell division. This ensures that sister chromatids are separated to opposite sides of the cytokinetic actomyosin ring (CAR). We show that, in fission yeast, spindle rotation is dependent on the interaction of astral microtubules with the cortical actin cytoskeleton. Interaction initially occurs with a region surrounding the nucleus, which we term the astral microtubule interaction zone (AMIZ). Simultaneous contact of astral microtubules from both poles with the AMIZ directs spindle rotation and this requires both actin and two type V myosins, Myo51 and Myo52. Astral microtubules from one pole only then contact the CAR, which is located at the centre of the AMIZ. We demonstrate that the anillin homologue Mid1, which dictates correct placement of the CAR, is necessary to stabilise the mitotic spindle perpendicular to the axis of cell division. Finally, we show that the position of the mitotic spindle is monitored by a checkpoint that regulates the timing of sister chromatid separation.
authors.affiliation: Department of Biology, University College London, London, UK.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Gachet
authors.forename: Sylvie
authors.initials: S
authors.lastname: Tournier
authors.forename: Jonathan B A
authors.initials: JB
authors.lastname: Millar
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Hyams
mesh_terms: D000199:Actins / Q000378:metabolism; D000705:Anaphase / Q000187:drug effects; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D003285:Contractile Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D024701:Myosin Type V / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism; D008941:Spindle Apparatus / Q000187:drug effects / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003285:Contractile Proteins; C489694:Mid1 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D013844:Thiazoles; D053778:Thiazolidines; C095886:anillin; D024701:Myosin Type V; C037068:latrunculin B