Parvovirus-induced depletion of cyclin B1 prevents mitotic entry of infected cells

PLoS Pathog. 2014 Jan;10(1):e1003891. doi: 10.1371/journal.ppat.1003891. Epub 2014 Jan 9.

Abstract

Parvoviruses halt cell cycle progression following initiation of their replication during S-phase and continue to replicate their genomes for extended periods of time in arrested cells. The parvovirus minute virus of mice (MVM) induces a DNA damage response that is required for viral replication and induction of the S/G2 cell cycle block. However, p21 and Chk1, major effectors typically associated with S-phase and G2-phase cell cycle arrest in response to diverse DNA damage stimuli, are either down-regulated, or inactivated, respectively, during MVM infection. This suggested that parvoviruses can modulate cell cycle progression by another mechanism. In this work we show that the MVM-induced, p21- and Chk1-independent, cell cycle block proceeds via a two-step process unlike that seen in response to other DNA-damaging agents or virus infections. MVM infection induced Chk2 activation early in infection which led to a transient S-phase block associated with proteasome-mediated CDC25A degradation. This step was necessary for efficient viral replication; however, Chk2 activation and CDC25A loss were not sufficient to keep infected cells in the sustained G2-arrested state which characterizes this infection. Rather, although the phosphorylation of CDK1 that normally inhibits entry into mitosis was lost, the MVM induced DDR resulted first in a targeted mis-localization and then significant depletion of cyclin B1, thus directly inhibiting cyclin B1-CDK1 complex function and preventing mitotic entry. MVM infection thus uses a novel strategy to ensure a pseudo S-phase, pre-mitotic, nuclear environment for sustained viral replication.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • CDC2 Protein Kinase
  • Cell Line
  • Checkpoint Kinase 2 / genetics
  • Checkpoint Kinase 2 / metabolism
  • Cyclin B1 / genetics
  • Cyclin B1 / metabolism*
  • Cyclin-Dependent Kinases / genetics
  • Cyclin-Dependent Kinases / metabolism
  • Enzyme Activation / genetics
  • G2 Phase Cell Cycle Checkpoints / genetics
  • Humans
  • Mice
  • Minute Virus of Mice / genetics
  • Minute Virus of Mice / metabolism*
  • Mitosis*
  • Parvoviridae Infections / genetics
  • Parvoviridae Infections / metabolism*
  • Parvoviridae Infections / pathology
  • S Phase Cell Cycle Checkpoints / genetics
  • cdc25 Phosphatases / genetics
  • cdc25 Phosphatases / metabolism

Substances

  • CCNB1 protein, human
  • Ccnb1 protein, mouse
  • Cyclin B1
  • Checkpoint Kinase 2
  • CHEK2 protein, human
  • Chek2 protein, mouse
  • CDC2 Protein Kinase
  • CDK1 protein, human
  • Cyclin-Dependent Kinases
  • CDC25A protein, human
  • Cdc25a protein, mouse
  • cdc25 Phosphatases