title: Dual mechanisms prevent premature chromosome segregation during meiosis.
abstract: In meiosis I, homologous chromosomes pair and then attach to the spindle so that the homologs can be pulled apart at anaphase I. The segregation of homologs before pairing would be catastrophic. We describe two mechanisms that prevent this. First, in early meiosis, Ipl1, the budding yeast homolog of the mammalian Aurora B kinase, triggers shedding of a kinetochore protein, preventing microtubule attachment. Second, Ipl1 localizes to the spindle pole bodies (SPBs), where it blocks spindle assembly. These processes are reversed upon expression of Ndt80. Previous studies have shown that Ndt80 is expressed when homologs have successfully partnered, and this triggers a rise in the levels of cyclin-dependent kinase (CDK). We found that CDK phosphorylates Ipl1, delocalizing it from SPBs, triggering spindle assembly. At the same time, kinetochores reassemble. Thus, dual mechanisms controlled by Ipl1 and Ntd80 coordinate chromosome and spindle behaviors to prevent the attachment of unpartnered chromosomes to the meiotic spindle.
authors.affiliation: Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA;
authors.forename: Seoyoung
authors.initials: S
authors.lastname: Kim
authors.forename: Régis
authors.initials: R
authors.lastname: Meyer
authors.forename: Hoa
authors.initials: H
authors.lastname: Chuong
authors.forename: Dean S
authors.initials: DS
authors.lastname: Dawson
mesh_terms: D064127:Aurora Kinases / Q000235:genetics / Q000378:metabolism*; D020090:Chromosome Segregation / Q000235:genetics / Q000502:physiology*; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D018386:Kinetochores / Q000378:metabolism; D008540:Meiosis / Q000235:genetics / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism; D010766:Phosphorylation; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; C097071:NDT80 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D064127:Aurora Kinases; C576961:IPL1 protein, S cerevisiae; D018844:Cyclin-Dependent Kinases
keywords: Cdc28; Clb4; Ipl1; kinetochores; meiosis; spindle pole body