Regulation of mitotic chromosome cohesion by Haspin and Aurora B

In vertebrate mitosis, cohesion between sister chromatids is lost in two stages. In prophase and prometaphase, cohesin release from chromosome arms occurs under the control of Polo-like kinase 1 and Aurora B, while Shugoshin is thought to prevent removal of centromeric cohesin until anaphase. The regulatory Enzymes that act to sustain centromeric cohesion are incompletely described, however. Haspin/Gsg2 is a histone H3 threonine-3 kinase required for normal mitosis. We report here that both H3 threonine-3 phosphorylation and cohesin are located at inner centromeres. Haspin depletion disrupts cohesin binding and sister chromatid association in mitosis, preventing normal chromosome alignment and activating the spindle assembly checkpoint, leading to arrest in a prometaphase-like state. Overexpression of Haspin hinders cohesin release and stabilizes arm cohesion. We conclude that Haspin is required to maintain centromeric cohesion during mitosis. We also suggest that Aurora B regulates cohesin removal through its effect on the localization of Shugoshin.