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Oxidative stress mislocalizes and retains transport factor importin-alpha and nucleoporins Nup153 and Nup88 in nuclei

Mohamed Kodiha1, Dan Tran, Cynthia Qian

  • 1Department of Physiology, McGill University, Montreal, PQ, Canada H3G 1Y6.

Biochimica Et Biophysica Acta
|December 11, 2007
PubMed

Insights

Oxidative stress disrupts nuclear transport by causing the nuclear retention of importin-alpha and nucleoporins Nup153/Nup88. This leads to altered protein interactions and nuclear accumulation, impacting cellular function.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Nuclear protein import is crucial for cellular function, relying on soluble transport factors and nucleoporins.
  • Classical nuclear import involves importin-alpha/beta1 and CAS, a protein that exports importin-alpha from the nucleus.

Purpose of the Study:

  • To investigate the impact of oxidative stress, induced by diethyl maleate (DEM), on classical nuclear transport pathways.
  • To identify the specific mechanisms by which oxidative stress affects the localization and interactions of nuclear transport components.

Main Methods:

  • Treatment of cells with diethyl maleate (DEM) to induce oxidative stress.
  • Analysis of the nucleocytoplasmic concentration gradient of Ran.
  • Assessment of reporter protein nuclear accumulation.
  • Examination of the cellular distribution of soluble transport factors and nucleoporins (importin-alpha, CAS, Nup153, Nup88).
  • In vitro and in vivo studies of protein-protein interactions and complex formation.

Main Results:

  • DEM treatment, without causing widespread cell death, interfered with reporter protein nuclear accumulation.
  • Oxidative stress altered the distribution of importin-alpha, CAS, Nup153, and Nup88 within cells.
  • Importin-alpha, CAS, Nup153, and Nup88 were found to accumulate in the nucleus under DEM treatment.
  • Importin-alpha formed high molecular mass complexes with Nup153 and Nup88 in the nucleus, an effect enhanced by oxidant treatment.
  • CAS did not appear to be part of these high molecular mass complexes.

Conclusions:

  • Oxidative stress significantly impacts the localization of soluble transport factors and nucleoporins.
  • Increased formation of nuclear complexes involving importin-alpha, Nup153, and Nup88 contributes to protein anchoring in the nucleus under oxidative stress.
  • These findings reveal a link between oxidative stress and altered protein interactions within the nuclear transport machinery.

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