Protection and deprotection of the Rec8 cohesin complex during meiosis

In the first meiotic division, the cohesin Rec8 is cleaved by separase along the chromosome arms but is protected at the centromere by shugoshin (Sgo1), maintaining centromeric cohesion throughout meiosis I. Another meiotic regulator, meikin (Moa1), supports the protective function of Sgo1 primarily by phosphorylating S450 of Rec8. Both Sgo1 and Moa1 are meiosis I-specific proteins. Unlike fission yeast Sgo1, mammalian shugoshin (SGO2) persists at centromeres throughout meiosis I and II, but REC8 cohesin is protected only during meiosis I. Here, we show that fission yeast Moa1 and Sgo1 appear at kinetochores/centromeres from prophase I to metaphase I and are degraded during anaphase I by the APC/C-Slp1 pathway. We expressed non-degradable versions of Moa1 and Sgo1 in meiosis II and investigated how these proteins protect the cohesin Rec8 during meiosis II. Our analyses suggest that the localization of Sgo1 and the phosphorylation of Rec8 at S449 and S450 are necessary and sufficient events for protecting Rec8 cohesin during meiosis II. The absence of either event leads to deprotection at meiosis II.