Nuclear retention of importin α coordinates cell fate through changes in gene expression

EMBO J. 2012 Jan 4;31(1):83-94. doi: 10.1038/emboj.2011.360. Epub 2011 Sep 30.

Abstract

Various cellular stresses including oxidative stress induce a collapse of the Ran gradient, which causes accumulation of importin α in the nucleus and a subsequent block of nuclear protein import. However, it is unknown whether accumulated importin α performs roles in the nucleus after its migration in response to stress. In this study, we found that nuclear-retained importin α2 binds with DNase I-sensitive nuclear component(s) and exhibits selective upregulation of mRNA encoding Serine/threonine kinase 35 (STK35) by microarray analysis. Chromatin immunoprecipitation and promoter analysis demonstrated that importin α2 can access to the promoter region of STK35 and accelerate its transcription in response to hydrogen peroxide exposure. Furthermore, constitutive overexpression of STK35 proteins enhances caspase-independent cell death under oxidative stress conditions. These results collectively reveal that nuclear-localized importin α2 influences gene expression and contributes directly to cell fate outcomes including non-apoptotic cell death.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Nucleus / metabolism*
  • Chromatin Immunoprecipitation
  • Gene Expression*
  • Mice
  • Nuclear Localization Signals / metabolism
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Oxidative Stress
  • Protein Kinases / genetics*
  • Protein Kinases / metabolism
  • Protein Serine-Threonine Kinases
  • RNA, Messenger / metabolism
  • Transfection
  • alpha Karyopherins / genetics
  • alpha Karyopherins / metabolism*

Substances

  • Nuclear Localization Signals
  • Nuclear Proteins
  • RNA, Messenger
  • alpha Karyopherins
  • Protein Kinases
  • Protein Serine-Threonine Kinases
  • STK35 protein, human