1. Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences,
2. Graduate Program in Biophysics and Biochemistry, University of Tokyo, and
3. SORST, Japan Science and Technology Agency, Yayoi, Tokyo 113-0032, Japan
4. National Institute of Advanced Industrial Science and Technology, Biological Information Research Center, Aomi, Tokyo 135-0064, Japan

Correspondence to: Yoshinori Watanabe^1,2,3 Correspondence and requests for materials should be addressed to Y.W. (Email: ywatanab@iam.u-tokyo.ac.jp).

Abstract

Sister chromatid cohesion, mediated by a complex called cohesin, is crucial—particularly at centromeres—for proper chromosome segregation in mitosis and meiosis. In animal mitotic cells, phosphorylation of cohesin promotes its dissociation from chromosomes, but centromeric cohesin is protected by shugoshin until kinetochores are properly captured by the spindle microtubules. However, the mechanism of shugoshin-dependent protection of cohesin is unknown. Here we find a specific subtype of serine/threonine protein phosphatase 2A (PP2A) associating with human shugoshin. PP2A colocalizes with shugoshin at centromeres and is required for centromeric protection. Purified shugoshin complex has an ability to reverse the phosphorylation of cohesin in vitro, suggesting that dephosphorylation of cohesin is the mechanism of protection at centromeres. Meiotic shugoshin of fission yeast also associates with PP2A, with both proteins collaboratively protecting Rec8-containing cohesin at centromeres. Thus, we have revealed a conserved mechanism of centromeric protection of eukaryotic chromosomes in mitosis and meiosis.

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