Kinetochore-localized PP1-Sds22 couples chromosome segregation to polar relaxation

Nature. 2015 Aug 27;524(7566):489-92. doi: 10.1038/nature14496. Epub 2015 Jul 13.


Cell division requires the precise coordination of chromosome segregation and cytokinesis. This coordination is achieved by the recruitment of an actomyosin regulator, Ect2, to overlapping microtubules at the centre of the elongating anaphase spindle. Ect2 then signals to the overlying cortex to promote the assembly and constriction of an actomyosin ring between segregating chromosomes. Here, by studying division in proliferating Drosophila and human cells, we demonstrate the existence of a second, parallel signalling pathway, which triggers the relaxation of the polar cell cortex at mid anaphase. This is independent of furrow formation, centrosomes and microtubules and, instead, depends on PP1 phosphatase and its regulatory subunit Sds22 (refs 2, 3). As separating chromosomes move towards the polar cortex at mid anaphase, kinetochore-localized PP1-Sds22 helps to break cortical symmetry by inducing the dephosphorylation and inactivation of ezrin/radixin/moesin proteins at cell poles. This promotes local softening of the cortex, facilitating anaphase elongation and orderly cell division. In summary, this identifies a conserved kinetochore-based phosphatase signal and substrate, which function together to link anaphase chromosome movements to cortical polarization, thereby coupling chromosome segregation to cell division.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Anaphase
  • Animals
  • Cell Polarity
  • Centrosome / metabolism
  • Chromatin / metabolism
  • Chromosome Segregation*
  • Cytoskeletal Proteins / metabolism
  • Drosophila melanogaster / cytology*
  • Drosophila melanogaster / enzymology
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / metabolism
  • Female
  • Humans
  • Kinetochores / enzymology
  • Kinetochores / metabolism*
  • Male
  • Membrane Proteins / metabolism
  • Microfilament Proteins / metabolism
  • Microtubules / metabolism
  • Phosphorylation
  • Protein Phosphatase 1 / metabolism*
  • Signal Transduction


  • Actins
  • Chromatin
  • Cytoskeletal Proteins
  • Membrane Proteins
  • Microfilament Proteins
  • PPP1R7 protein, human
  • ezrin
  • moesin
  • radixin
  • Protein Phosphatase 1