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Nuclear export determines the cytokine sensitivity of STAT transcription factors

Inga Lödige1, Andreas Marg, Burkhard Wiesner

  • 1Abteilung Zelluläre Signalverarbeitung, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Freie Universität Berlin, 13125 Berlin, Germany.

The Journal of Biological Chemistry
|October 1, 2005
PubMed

Insights

STAT transcription factors

Area of Science:

  • Cellular signaling pathways
  • Molecular biology
  • Gene regulation

Background:

  • Cytokine signaling relies on STAT transcription factor activation via tyrosine phosphorylation.
  • STAT activation specificity is mainly determined by SH2 domain complementarity.

Purpose of the Study:

  • To investigate nucleocytoplasmic shuttling as a mechanism controlling STAT transcription factor differential activation.
  • To analyze the role of STAT1 splice variants and their transactivation domains in regulating cytokine signaling.

Main Methods:

  • Analysis of STAT1 nucleocytoplasmic cycling.
  • Investigating the impact of alternatively spliced transactivation domains and serine phosphorylation on nuclear export.
  • Assessing export modulation independent of retention factors or CRM1.
  • Evaluating the dual role of the transactivation domain on activated and inactivated STAT1.

Main Results:

  • Nucleocytoplasmic shuttling is identified as a mechanism controlling STAT differential activation.
  • STAT1 splice variants exhibit differential tyrosine phosphorylation and signal duration.
  • The transactivation domain plays a dual role, enhancing activated STAT1 nuclear retention but promoting inactivated STAT1 export.
  • Regulated nuclear export controls STAT1 availability at the receptor kinase complex.

Conclusions:

  • Regulated nuclear export determines cytokine sensitivity of STAT transcription factors.
  • Alternative splicing and serine phosphorylation of the transactivation domain modulate STAT1 nuclear export rates.
  • This mechanism fine-tunes STAT1 availability and signaling amplitude in response to cytokines.

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