The EhCPADH112 complex of Entamoeba histolytica interacts with tight junction proteins occludin and claudin-1 to produce epithelial damage

PLoS One. 2013 Jun 7;8(6):e65100. doi: 10.1371/journal.pone.0065100. Print 2013.

Abstract

Entamoeba histolytica, the protozoan responsible for human amoebiasis, causes between 30,000 and 100,000 deaths per year worldwide. Amoebiasis is characterized by intestinal epithelial damage provoking severe diarrhea. However, the molecular mechanisms by which this protozoan causes epithelial damage are poorly understood. Here, we studied the initial molecular interactions between the E. histolytica EhCPADH112 virulence complex and epithelial MDCK and Caco-2 cells. By confocal microscopy, we discovered that after contact with trophozoites or trophozoite extracts (TE), EhCPADH112 and proteins forming this complex (EhCP112 and EhADH112) co-localize with occludin and claudin-1 at tight junctions (TJ). Immunoprecipitation assays revealed interaction between EhCPADH112 and occludin, claudin-1, ZO-1 and ZO-2. Overlay assays confirmed an interaction of EhCP112 and EhADH112 with occludin and claudin-1, whereas only EhADH112 interacted also with ZO-2. We observed degradation of all mentioned TJ proteins after incubation with TE. Importantly, inhibiting proteolytic activity or blocking the complex with a specific antibody not only prevented TJ protein degradation but also epithelial barrier disruption. Furthermore, we discovered that TE treatment induces autophagy and apoptosis in MDCK cells that could contribute to the observed barrier disruption. Our results suggest a model in which epithelial damage caused by E. histolytica is initiated by the interaction of EhCP112 and EhADH112 with TJ proteins followed by their degradation. Disruption of TJs then induces increased paracellular permeability, thus facilitating the entry of more proteases and other parasite molecules leading eventually to tissue destruction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Autophagy
  • Caco-2 Cells
  • Claudin-1 / metabolism*
  • Dogs
  • Entamoeba histolytica / metabolism*
  • Entamoeba histolytica / pathogenicity
  • Epithelial Cells / metabolism
  • Epithelial Cells / parasitology*
  • Epithelial Cells / pathology*
  • Humans
  • Immunoprecipitation
  • Madin Darby Canine Kidney Cells
  • Models, Biological
  • Necrosis
  • Occludin / metabolism*
  • Protein Binding
  • Protein Transport
  • Protozoan Proteins / metabolism*
  • Trophozoites / metabolism
  • Virulence

Substances

  • Claudin-1
  • Occludin
  • Protozoan Proteins

Grants and funding

This study was supported by the European Economic Community (Phagoamoeba project ICA4-CT-2001-10073) and the Institute of Science and Technology of the Federal District (grant number 64/2012). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.