EGF-induced dynamics of NF-κB and F-actin in A431 cells spread on fibronectin

Histochem Cell Biol. 2015 Sep;144(3):223-35. doi: 10.1007/s00418-015-1331-5. Epub 2015 May 20.

Abstract

To evaluate the role of actin cytoskeleton in the regulation of NF-κB transcription factor, we analyzed its involvement in the intracellular transport and nuclear translocation of the NF-κB RelA/p65 subunit in A431 epithelial cells stimulated with fibronectin and EGF. Live cell imaging and confocal microscopy showed that EGF activated the movement of RelA/p65 in the cytoplasm. Upon cell adhesion to fibronectin, RelA/p65 concentrated onto stress fibers, and EGF stimulated its subsequent allocation to membrane ruffles, newly organized stress fibers, and discrete cytoplasmic actin-rich patches. These patches also contained α-actinin-1 and α-actinin-4, vinculin, paxillin, α-tubulin, and PI3-kinase. Cytochalasin D treatment resulted in RelA/p65 redistribution to actin-containing aggregates, with the number of cells with RelA/p65-containing clusters in the cytoplasm increasing under the effect of EGF. Furthermore, EGF proved to induce RelA/p65 accumulation in the nucleus after cell pretreatment with actin-stabilizing and actin-destabilizing agents, which was accompanied by changes in its DNA-binding activity after either EGF stimulation or cytochalasin D treatment. Thus, EGF treatment of A431 cells results in simultaneous nuclear RelA/p65 translocation and cytoplasmic redistribution, with part of RelA/p65 pool forming a very tight association with actin-rich structures. Apparently, nuclear transport is independent on drug stabilization or destabilization of the actin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / drug effects
  • Actins / metabolism*
  • Cell Line
  • Cell Line, Tumor
  • Cytochalasin D / pharmacology
  • Cytoplasm / drug effects
  • Cytoplasm / metabolism
  • Epidermal Growth Factor / pharmacology*
  • Fibronectins / metabolism*
  • Humans
  • NF-kappa B / biosynthesis
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Transcription Factor RelA / drug effects
  • Transcription Factor RelA / metabolism*
  • Translocation, Genetic / drug effects

Substances

  • Actins
  • Fibronectins
  • NF-kappa B
  • Nucleic Acid Synthesis Inhibitors
  • RELA protein, human
  • Transcription Factor RelA
  • Cytochalasin D
  • Epidermal Growth Factor