Aurora B prevents chromosome arm separation defects by promoting telomere dispersion and disjunction.
Bottom Line: Dispersion is promoted by the dissociation of Swi6/HP1 and cohesin Rad21 from telomeres, whereas disjunction occurs at anaphase after the phosphorylation of condensin subunit Cnd2.Strikingly, we demonstrate that deletion of Ccq1, a telomeric shelterin component, rescued cell death after Aurora inhibition by promoting the loading of condensin on chromosome arms.Our findings reveal an essential role for telomeres in chromosome arm segregation.
Affiliation: Laboratoire de biologie cellulaire et moléculaire du contrôle de la prolifération, Université de Toulouse, F-31062 Toulouse, France Centre National de la Recherche Scientifique, LBCMCP-UMR5088, F-31062 Toulouse, France.Show MeSH
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Mentions: In fission yeast, Aurora B–dependent phosphorylation of the kleisin Cnd2 promotes condensin recruitment to chromosomes (Nakazawa et al., 2011; Tada et al., 2011). To clarify how Ccq1 deletion rescued Aurora inhibition, we performed single cell analysis of condensin (cnd1-gfp) recruitment on chromosomes during mitosis in control cells, ccq1Δ cells, and phosphomimetic cnd2-3E mutant. As previously described, condensin colocalizes to several nuclear compartments during mitosis (Nakazawa et al., 2008), including the nucleolus (rDNA) and kinetochores. At anaphase onset, condensin localization switches to chromosome arms (Fig. 8 D, bottom, Hoechst) and the spindle midzone (Fig. 8, B and D). Transient localization of condensin with telomere clusters was also occasionally observed during metaphase (Fig. 8 D). In ccq1Δ cells and cnd2-3E mutant, this mitotic pattern of condensin localization was unchanged (Fig. 8, C and E, top). However, we noted that although Pot1 decreased in mitosis in control and ccq1Δ cells, it remained strongly associated with telomeres in the cnd2-3E mutant.
Affiliation: Laboratoire de biologie cellulaire et moléculaire du contrôle de la prolifération, Université de Toulouse, F-31062 Toulouse, France Centre National de la Recherche Scientifique, LBCMCP-UMR5088, F-31062 Toulouse, France.