Nuclear translocation of STAT3 and NF-κB are independent of each other but NF-κB supports expression and activation of STAT3

Cell Signal. 2017 Apr;32:36-47. doi: 10.1016/j.cellsig.2017.01.006. Epub 2017 Jan 9.

Abstract

NF-κB and STAT3 are essential transcription factors in immunity and act at the interface of the transition from chronic inflammation to cancer. Different functional crosstalks between NF-κB and STAT3 have been recently described arguing for a direct interaction of both proteins. During a systematic analysis of NF-κB/STAT3 crosstalk we observed that appearance of the subcellular distribution of NF-κB and STAT3 in immunofluorescence heavily depends on the fixation procedure. Therefore, we established an optimized fixation protocol for the reliable simultaneous analysis of the subcellular distributions of both transcription factors. Using this protocol we found that cytokine-induced nuclear accumulation of NF-κB or STAT3 did not alter the subcellular distribution of the other transcription factor. Both knockout and overexpression of STAT3 does not have any major effect on canonical TNFα-NF-κB signalling in MEF or HeLa cells. Similarly, knockout of p65 did not alter nuclear accumulation of STAT3 in response to IL-6. However, p65 expression correlates with elevated total cellular levels of STAT3 and STAT1 and supports activation of these transcription factors. Our findings in MEF cells argue against a direct physical interaction of free cellular NF-κB and STAT3 but point to more intricate functional interactions.

Keywords: Crosstalk; NF-κB; Nuclear translocation; STAT3; Signal transduction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Nucleus / drug effects
  • Cell Nucleus / metabolism*
  • Gene Expression Regulation / drug effects
  • HeLa Cells
  • Humans
  • Mice
  • NF-kappa B / metabolism*
  • Protein Transport / drug effects
  • STAT1 Transcription Factor / metabolism
  • STAT3 Transcription Factor / metabolism*
  • STAT5 Transcription Factor / metabolism
  • Transcription Factor RelA / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • NF-kappa B
  • STAT1 Transcription Factor
  • STAT3 Transcription Factor
  • STAT5 Transcription Factor
  • Transcription Factor RelA
  • Tumor Necrosis Factor-alpha