ATF3 plays a key role in Kdo2-lipid A-induced TLR4-dependent gene expression via NF-κB activation

PLoS One. 2010 Dec 2;5(12):e14181. doi: 10.1371/journal.pone.0014181.

Abstract

Background: Activating transcription factor 3 (ATF3) is a negative regulator of proinflammatory cytokine expression in macrophages, and ATF3 deficient mice are more susceptible to endotoxic shock. This study addresses the role of ATF3 in the Kdo(2)-Lipid A-induced Toll-like receptor 4 (TLR4) signaling pathway in mouse embryonic fibroblasts (MEF). Kdo(2)-Lipid A upregulates ATF3 expression in wild type MEF cells and induces both nuclear factor kappa B (NF-κB) and c-Jun N-terminal kinase (JNK) activation via the TLR4 signaling pathway, while neither of these pathways is activated in ATF3-/- MEF cells. Interestingly, in contrast to Kdo(2)-Lipid A, the activation of both NF-κB and JNK by TNF-α was normal in ATF3-/- MEF cells.

Methodology/principal findings: We found that several genes were dramatically upregulated in ATF3+/+ MEF cells in response to Kdo(2)-Lipid A treatment, while little difference was observed in the ATF3-/- MEF cells. However, we also found that the signal intensities of IκBζ in ATF3-/- MEF cells were substantially higher than those in wild type MEF cells upon microarray analyses, and upregulated IκBζ expression was detected in the cytosol fraction.

Conclusions/significance: Our findings indicate that ATF3 deficiency affects Kdo(2)-Lipid A-induced TLR4 signaling pathways in MEF cells, that it may upregulate IκBζ expression and that the high levels of IκBζ expression in ATF3-/- cells disrupts Kdo(2)-Lipid A-mediated signaling pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activating Transcription Factor 3 / metabolism*
  • Animals
  • Cell Line
  • Cells, Cultured
  • Fibroblasts / metabolism
  • Gene Expression Regulation*
  • Lipid A / metabolism
  • Lipopolysaccharides / chemistry*
  • MAP Kinase Kinase 4 / metabolism
  • Mice
  • NF-kappa B / metabolism*
  • Oligonucleotide Array Sequence Analysis
  • Signal Transduction
  • Toll-Like Receptor 4 / chemistry*
  • Transcription, Genetic

Substances

  • ATF3 protein, human
  • Activating Transcription Factor 3
  • Kdo2-lipid A
  • Lipid A
  • Lipopolysaccharides
  • NF-kappa B
  • TLR4 protein, human
  • Toll-Like Receptor 4
  • MAP Kinase Kinase 4