Ki-67 is a PP1-interacting protein that organises the mitotic chromosome periphery

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Abstract
When the nucleolus disassembles during open mitosis, many nucleolar proteins and RNAs associate with chromosomes, establishing a perichromosomal compartment coating the chromosome periphery. At present nothing is known about the function of this poorly characterised compartment. In this study, we report that the nucleolar protein Ki-67 is required for the assembly of the perichromosomal compartment in human cells. Ki-67 is a cell-cycle regulated protein phosphatase 1-binding protein that is involved in phospho-regulation of the nucleolar protein B23/nucleophosmin. Following siRNA depletion of Ki-67, NIFK, B23, nucleolin, and four novel chromosome periphery proteins all fail to associate with the periphery of human chromosomes. Correlative light and electron microscopy (CLEM) images suggest a near-complete loss of the entire perichromosomal compartment. Mitotic chromosome condensation and intrinsic structure appear normal in the absence of the perichromosomal compartment but significant differences in nucleolar reassembly and nuclear organisation are observed in post-mitotic cells.
Funding Information
  • Wellcome Trust (073915)
  • Biotechnology and Biological Sciences Research Council (BB/K017632/1)
  • Wellcome Trust (Centre Core Grant, 077707)
  • Wellcome Trust (077248)
  • Brunel BRIEF award (LBL301)
  • Wellcome Trust (Instrument Grant, 091020)
  • Medical Research Council programme grant
  • RIKEN Incentive Research Fund
  • Japan Society for the Promotion of Science (KAKENHI, 24657124)
  • RIKEN Special Project Funding for Basic Science in Cellular System Project Research
  • Wellcome Trust (073915)
  • Biotechnology and Biological Sciences Research Council (BB/K017632/1)
  • Wellcome Trust (Centre Core Grant, 077707)
  • Wellcome Trust (077248)
  • Brunel BRIEF award (LBL301)
  • Wellcome Trust (Instrument Grant, 091020)
  • Medical Research Council programme grant
  • RIKEN Incentive Research Fund
  • Japan Society for the Promotion of Science (KAKENHI, 24657124)
  • RIKEN Special Project Funding for Basic Science in Cellular System Project Research

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