Claudin-3 is required for modulation of paracellular permeability by TNF-α through ERK1/2/slug signaling axis in submandibular gland

Cell Signal. 2015 Oct;27(10):1915-27. doi: 10.1016/j.cellsig.2015.07.002. Epub 2015 Jul 3.

Abstract

TNF-α plays an important role in the pathogenesis of salivary inflammatory diseases. Salivary dysfunction, which leads to impaired saliva secretion, can be caused by TNF-α-induced disrupted epithelial barrier. However, the signaling mechanism involved in TNF-α-modulated tight junction barrier in salivary gland remains unclear. Here, we found that TNF-α reduced transepithelial resistance (TER) and increased FITC-dextran flux in a rat submandibular cell line SMG-C6. Claudin (Cln)-3 was selectively downregulated and disrupted by TNF-α, whereas Cln-1, Cln-4, and β-catenin were not affected. Overexpression of Cln-3 retained and Cln-3 knockdown abolished the TNF-α-induced alterations. Moreover, TNF-α increased extracellular signal-regulated kinase (ERK1/2) phosphorylation and the expression of transcriptional factor slug. ERK1/2 kinase inhibitor PD98059 abrogated TNF-α-induced increase in paracellular permeability, alterations of Cln-3, and elevation of slug. Overexpression of slug decreased and slug knockdown increased Cln-3 expression. In addition, slug bind to the E-box elements of Cln-3 promoter in TNF-α-treated cells, and this response was blocked by PD98059. Furthermore, TNF-α decreased Cln-3 expression and increased slug content in cultured human submandibular gland. Taken together, our data suggest that Cln-3 plays a vital role in TNF-α-modulated paracellular permeability in submandibular epithelium and ERK1/2/slug signaling axis is involved in alteration of Cln-3 redistribution and downregulation.

Keywords: Claudin-3; ERK1/2; Paracellular permeability; Slug; Submandibular gland; TNF-α.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Cell Line
  • Cell Membrane Permeability
  • Claudin-3 / physiology*
  • Epithelial Cells / metabolism
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Gene Expression
  • Gene Expression Regulation
  • Humans
  • MAP Kinase Signaling System*
  • Male
  • Middle Aged
  • Promoter Regions, Genetic
  • Protein Transport
  • Rats
  • Snail Family Transcription Factors
  • Submandibular Gland
  • Tight Junctions / metabolism
  • Transcription Factors / metabolism
  • Tumor Necrosis Factor-alpha / metabolism*

Substances

  • CLDN3 protein, human
  • Claudin-3
  • SNAI1 protein, human
  • Snai2 protein, rat
  • Snail Family Transcription Factors
  • TNF protein, human
  • Transcription Factors
  • Tumor Necrosis Factor-alpha
  • Extracellular Signal-Regulated MAP Kinases