title: A pathway containing the Ipl1/aurora protein kinase and the spindle midzone protein Ase1 regulates yeast spindle assembly.
abstract: It is critical to elucidate the pathways that mediate spindle assembly and therefore ensure accurate chromosome segregation during cell division. Our studies of a unique allele of the budding yeast Ipl1/Aurora protein kinase revealed that it is required for centrosome-mediated spindle assembly in the absence of the BimC motor protein Cin8. In addition, we found that the Ase1 spindle midzone-associated protein is required for bipolar spindle assembly. The cin8 ipl1 and cin8 ase1 double mutant cells exhibit similar defects, and Ase1 overexpression completely restores spindle assembly in cin8 ipl1 strains. Consistent with the possibility that Ipl1 regulates Ase1, an ase1 mutant lacking the Ipl1 consensus phosphorylation sites cannot assemble spindles in the absence of Cin8. In addition, Ase1 phosphorylation and localization were altered in an ipl1 mutant. We therefore propose that Ipl1/Aurora and Ase1 constitute a previously unidentified spindle assembly pathway that becomes essential in the absence of Cin8.
authors.affiliation: Fred Hutchinson Cancer Research Center, Division of Basic Sciences, 1100 Fairview Avenue North, P.O. Box 19024, Seattle, WA 98109, USA.
authors.forename: Chitra V
authors.initials: CV
authors.lastname: Kotwaliwale
authors.forename: Stéphanie Buvelot
authors.initials: SB
authors.lastname: Frei
authors.forename: Bodo M
authors.initials: BM
authors.lastname: Stern
authors.forename: Sue
authors.initials: S
authors.lastname: Biggins
mesh_terms: D064127:Aurora Kinases; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation; D010766:Phosphorylation; D011233:Precipitin Tests; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D008941:Spindle Apparatus / Q000201:enzymology*
chemical_list: C472767:Ase1 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; D064127:Aurora Kinases; C576961:IPL1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases