Human Bub1 defines the persistent cohesion site along the mitotic chromosome by affecting Shugoshin localization.
Shugoshin (Sgo) proteins constitute a conserved protein family defined as centromeric protectors of Rec8-containing cohesin complexes in meiosis . In vertebrate mitosis, Scc1/Rad21-containing cohesin complexes are also protected at centromeres because arm cohesin, but not centromeric cohesin, is largely dissociated in pro- and prometaphase . The dissociation process is dependent on the activity of polo-like kinase (Plk1) and partly dependent on Aurora B . Recently, it has been demonstrated that vertebrate shugoshin is required for preserving centromeric cohesion during mitosis ; however, it was not addressed whether human shugoshin protects cohesin itself. Here, we show that the persistence of human Scc1 at centromeres in mitosis is indeed dependent on human Sgo1. In fission yeast, Sgo localization depends on Bub1, a conserved spindle checkpoint protein, which is enigmatically also required for chromosome congression during prometaphase in vertebrate cells. We demonstrate that human Sgo1 fails to localize at centromeres in Bub1-repressed cells, and centromeric cohesion is significantly loosened. Remarkably, in these cells, Sgo1 relocates to chromosomes all along their length and provokes ectopic protection from dissociation of Scc1 on chromosome arms. These results reveal a hitherto concealed role for human Bub1 in defining the persistent cohesion site of mitotic chromosomes.
Kitajima
Tomoya S
TS
Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi, Tokyo 113-0032, Japan.
Hauf
Silke
S
Ohsugi
Miho
M
Yamamoto
Tadashi
T
Watanabe
Yoshinori
Y
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D002875:Chromosomes / Q000378:metabolism*; D003001:Cloning, Molecular; D020732:Cytogenetic Analysis; D017931:DNA Primers; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D008938:Mitosis / Q000502:physiology*; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011494:Protein Kinases / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D034622:RNA Interference; D029701:Saccharomyces cerevisiae Proteins
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D017931:DNA Primers; C490529:MCD1 protein, S cerevisiae; D009687:Nuclear Proteins; D010750:Phosphoproteins; C496644:SGO1 protein, human; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases