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Hydrogen peroxide inhibition of nuclear protein import is mediated by the mitogen-activated protein kinase, ERK2

M P Czubryt1, J A Austria, G N Pierce

  • 1Cell Biology Laboratory, Division of Stroke and Vascular Disease, St. Boniface General Hospital Research Centre and the Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada R2H 2A6.

The Journal of Cell Biology
|January 12, 2000
PubMed

Insights

Hydrogen peroxide (H2O2) inhibits nuclear protein import in cells by activating mitogen-activated protein kinase (MAPK) signaling. This process involves changes in cytosolic Ran/TC4 levels and can be reversed by catalase or MAPK inhibitors.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Hydrogen peroxide (H2O2) is known to alter gene expression in various cell types.
  • Changes in nuclear import of key proteins, such as transcription factors, are hypothesized to underlie these gene expression alterations.

Purpose of the Study:

  • To investigate the effect of H2O2 on the nuclear import of proteins.
  • To elucidate the molecular mechanisms by which H2O2 influences nuclear import.

Main Methods:

  • In vitro nuclear import assays using a cytosolic import cocktail treated with varying concentrations of H2O2.
  • Western blotting to detect protein activation (ERK2).
  • Inhibition studies using specific MEK1/2 inhibitor (PD98059).
  • Immunocytochemistry to assess changes in cytosolic Ran/TC4 levels.

Main Results:

  • H2O2 caused a dose- and time-dependent inhibition of nuclear import at concentrations as low as 100 microM, an effect reversible by catalase.
  • H2O2's inhibitory effect on import was localized to a cytosolic factor and distinct from hydroxyl or superoxide radicals.
  • H2O2 activated ERK2, and its effects on import were blocked by a MEK1/2 inhibitor (PD98059). Activated ERK2 mimicked H2O2's inhibitory effect.
  • H2O2 treatment increased cytosolic Ran/TC4 levels, which was reversed by catalase or PD98059.

Conclusions:

  • H2O2 inhibits nuclear protein import.
  • This inhibition is mediated by mitogen-activated protein (MAP) kinase activation, likely through alterations in Ran/TC4 function.
  • The findings reveal a novel signaling pathway linking oxidative stress to nuclear transport regulation.

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