Greatwall is essential to prevent mitotic collapse after nuclear envelope breakdown in mammals

Proc Natl Acad Sci U S A. 2013 Oct 22;110(43):17374-9. doi: 10.1073/pnas.1310745110. Epub 2013 Oct 7.

Abstract

Greatwall is a protein kinase involved in the inhibition of protein phosphatase 2 (PP2A)-B55 complexes to maintain the mitotic state. Although its biochemical activity has been deeply characterized in Xenopus, its specific relevance during the progression of mitosis is not fully understood. By using a conditional knockout of the mouse ortholog, Mastl, we show here that mammalian Greatwall is essential for mouse embryonic development and cell cycle progression. Yet, Greatwall-null cells enter into mitosis with normal kinetics. However, these cells display mitotic collapse after nuclear envelope breakdown (NEB) characterized by defective chromosome condensation and prometaphase arrest. Intriguingly, Greatwall is exported from the nucleus to the cytoplasm in a CRM1-dependent manner before NEB. This export occurs after the nuclear import of cyclin B-Cdk1 complexes, requires the kinase activity of Greatwall, and is mediated by Cdk-, but not Polo-like kinase 1-dependent phosphorylation. The mitotic collapse observed in Greatwall-deficient cells is partially rescued after concomitant depletion of B55 regulatory subunits, which are mostly cytoplasmic before NEB. These data suggest that Greatwall is an essential protein in mammals required to prevent mitotic collapse after NEB.

Keywords: cell cycle regulation; cell division; mitotic kinases; mitotic phosphatases; nuclear export.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Amino Acid Sequence
  • Animals
  • Cell Line, Tumor
  • Cells, Cultured
  • Embryo, Mammalian / cytology
  • Embryo, Mammalian / embryology
  • Embryo, Mammalian / metabolism
  • Female
  • Humans
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Male
  • Mammals / embryology
  • Mammals / genetics
  • Mammals / metabolism
  • Mice
  • Mice, Knockout
  • Microscopy, Fluorescence
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism*
  • Mitosis*
  • Nuclear Envelope / metabolism*
  • Protein Phosphatase 2 / genetics
  • Protein Phosphatase 2 / metabolism
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA Interference
  • Sequence Homology, Amino Acid
  • Time Factors

Substances

  • Luminescent Proteins
  • Microtubule-Associated Proteins
  • Protein Subunits
  • Protein-Serine-Threonine Kinases
  • greatwall protein, mouse
  • Protein Phosphatase 2