Shugoshin and PP2A, shared duties at the centromere.
Sister chromatid cohesion mediated by the ring-shaped cohesin complex is essential for faithful chromosome segregation. A tight spatial and temporal control of cohesin release is observed in mitosis and meiosis, and a family of proteins known as shugoshins play a major role in this process. Shugoshin (Sgo) protects centromeric cohesin from dissociation in early mitosis and from cleavage by separase in meiosis I. Three exciting new reports indicate that this is accomplished by recruiting the serine/threonine protein phosphatase 2A (PP2A) to centromeres.((1-3)) The proposed targets of PP2A activity include cohesin and Sgo, both of which would otherwise dissociate from chromosomes upon phosphorylation by Polo kinase. Thus, a balance of kinase and phosphatase activities seems to be the key to the conserved mechanism that regulates the stepwise release of cohesin from mitotic and meiotic chromosomes. Additional evidence, however, suggests that this is only part of the story, and that Sgo has also a role independent of PP2A.
Rivera
Teresa
T
Chromosome Dynamics Group, Spanish National Cancer Center (CNIO), Madrid, Spain.
Losada
Ana
A
D018797:Cell Cycle Proteins / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D006801:Humans; D008540:Meiosis; D008938:Mitosis; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D054648:Protein Phosphatase 2; D017346:Protein Serine-Threonine Kinases; D000097722:Cohesins
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D009687:Nuclear Proteins; D010749:Phosphoprotein Phosphatases; D011494:Protein Kinases; D054648:Protein Phosphatase 2; D017346:Protein Serine-Threonine Kinases; D000097722:Cohesins; C496644:SGO1 protein, human; C090464:Bub1 spindle checkpoint protein