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

Elife. 2014 May 27;3:e01641. doi: 10.7554/eLife.01641.

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.DOI: http://dx.doi.org/10.7554/eLife.01641.001.

Keywords: chromosomes; mitosis; nucleolus; phosphatases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Nucleolus / metabolism*
  • Cell Nucleolus / ultrastructure
  • Chromosomes, Human / metabolism*
  • Chromosomes, Human / ultrastructure
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Ki-67 Antigen / genetics
  • Ki-67 Antigen / metabolism*
  • Microscopy, Electron
  • Mitosis*
  • Molecular Sequence Data
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Protein Phosphatase 1 / metabolism*
  • RNA Interference
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • Sequence Analysis, Protein
  • Signal Transduction
  • Transfection

Substances

  • Intracellular Signaling Peptides and Proteins
  • Ki-67 Antigen
  • NIFK protein, human
  • Nuclear Proteins
  • Phosphoproteins
  • RNA-Binding Proteins
  • nucleolin
  • nucleophosmin
  • Protein Phosphatase 1