Acetaldehyde disrupts tight junctions in Caco-2 cell monolayers by a protein phosphatase 2A-dependent mechanism

Mitzi Dunagan, Kamaljit Chaudhry, Geetha Samak, Radhakrishna Rao

Research output: Contribution to journalArticle

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Abstract

Acetaldehyde is accumulated at high concentrations in the colonic lumen following ethanol administration. Previous studies demonstrated that acetaldehyde disrupts intestinal epithelial tight junctions and increases paracellular permeability. In the present study, we investigated the role of PP2A in the acetaldehyde-induced disruption of intestinal epithelial tight junctions. Caco-2 cell monolayers were exposed to 200-600 μM acetaldehyde for varying times, and the epithelial barrier function was evaluated by measuring transepithelial electrical resistance and inulin permeability. Acetaldehyde treatment resulted in a time-dependent increase in inulin permeability and redistribution of occludin and ZO-1 from the intercellular junctions. Treatment of cells with fostriecin (a PP2A-selective inhibitor) or knockdown of PP2A by siRNA blocked acetaldehyde-induced increase in inulin permeability and redistribution of occludin and ZO-1. The effects of fostriecin and acetaldehyde were confirmed in mouse intestine ex vivo. Acetaldehyde- induced tight junction disruption and barrier dysfunction were also attenuated by a PP2A-specific inhibitory peptide, TPDYFL. Coimmunoprecipitation studies showed that acetaldehyde increased the interaction of PP2A with occludin and induced dephosphorylation of occludin on threonine residues. Fostriecin and TPDYFL significantly reduced acetaldehyde-induced threonine dephosphorylation of occludin. Acetaldehyde failed to change the level of the methylated form of PP2A-C subunit. However, genistein (a tyrosine kinase inhibitor) blocked acetaldehyde-induced association of PP2A with occludin and threonine dephosphorylation of occludin. These results demonstrate that acetaldehyde-induced disruption of tight junctions is mediated by PP2A translocation to tight junctions and dephosphorylation of occludin on threonine residues.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume303
Issue number12
DOIs
StatePublished - Dec 15 2012

Fingerprint

Protein Phosphatase 2
Caco-2 Cells
Acetaldehyde
Tight Junctions
Occludin
Threonine
Inulin
Permeability
Intercellular Junctions
Genistein
Electric Impedance
Protein-Tyrosine Kinases
Small Interfering RNA
Intestines

All Science Journal Classification (ASJC) codes

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

Cite this

Acetaldehyde disrupts tight junctions in Caco-2 cell monolayers by a protein phosphatase 2A-dependent mechanism. / Dunagan, Mitzi; Chaudhry, Kamaljit; Samak, Geetha; Rao, Radhakrishna.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 303, No. 12, 15.12.2012.

Research output: Contribution to journalArticle

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