Protection and deprotection of the Rec8 cohesin complex during meiosis.
During meiosis I, the cohesin Rec8 is cleaved by separase along the chromosome arms but is protected at the centromere by shugoshin (Sgo1); during meiosis II, it is not protected. In fission yeast, another meiotic regulator, meikin (Moa1), supports the protective function of Sgo1 primarily by phosphorylating Rec8 at S450. Here we show that both meiosis I-specific proteins, Sgo1 and Moa1, are degraded during anaphase I by the APC/C-Slp1 pathway. To explore the possibility of ectopic protection during meiosis II, we expressed non-degradable forms of Moa1 and Sgo1 during meiosis. Our analyses revealed that stabilization of the Sgo1 protein and phosphorylation of Rec8 at S449 and S450 are necessary and sufficient for the protection of Rec8 cohesin during meiosis II. Furthermore, our results suggest that the phosphorylation-dependent interaction between Rec8 and Sgo1 during meiosis is prominent at mono-oriented kinetochores but not at bi-oriented kinetochores.
Liu Y, Zhang K, Bai Z, Sun L, Hou H, Watanabe Y