Sli15(INCENP) dephosphorylation prevents mitotic checkpoint reengagement due to loss of tension at anaphase onset.
The mitotic checkpoint, also known as the spindle assembly checkpoint, delays anaphase onset until all chromosomes have reached bipolar tension on the mitotic spindle [1-3]. Once this is achieved, the protease separase is activated to cleave the chromosomal cohesin complex, thereby triggering anaphase. Cohesin cleavage releases tension between sister chromatids, but why the mitotic checkpoint now remains silent is poorly understood. Here, using budding yeast as a model, we show that loss of sister chromatid cohesion at anaphase onset would engage the mitotic checkpoint if this was not prevented by concomitant separase-dependent activation of the Cdc14 phosphatase. Cdc14, in turn, inactivates the mitotic checkpoint by dephosphorylating Sli15(INCENP), a subunit of the conserved Aurora B kinase complex that forms part of the proposed chromosomal tension sensor. Dephosphorylation-dependent relocation of Sli15(INCENP) from centromeres to the central spindle during anaphase is seen in organisms from yeast to human [4-8]. Our results suggest that Sli15(INCENP) dephosphorylation is part of an evolutionarily conserved mechanism that prevents the mitotic checkpoint from reengaging when tension between sister chromatids is lost at anaphase onset.
Mirchenko
Lesia
L
Chromosome Segregation Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London, UK.
Uhlmann
Frank
F
D000705:Anaphase; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002842:Chromatids / Q000502:physiology; D010450:Endopeptidases / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D064247:Separase; D008941:Spindle Apparatus / Q000502:physiology
C074860:CDC14 protein, S cerevisiae; D018797:Cell Cycle Proteins; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; C480084:Sli15 protein, S cerevisiae; D017027:Protein Tyrosine Phosphatases; D010450:Endopeptidases; C577986:ESP1 protein, S cerevisiae; C577987:ESPL1 protein, human; D064247:Separase