Truncation mutants of the tight junction protein ZO-1 disrupt corneal epithelial cell morphology

Mol Biol Cell. 2000 May;11(5):1687-96. doi: 10.1091/mbc.11.5.1687.


The tight junction is the most apical intercellular junction of epithelial cells and regulates transepithelial permeability through the paracellular pathway. To examine possible functions for the tight junction-associated protein ZO-1, C-terminally truncated mutants and a deletion mutant of ZO-1 were epitope tagged and stably expressed in corneal epithelial cell lines. Only full-length ZO-1 and one N-terminal truncation mutant targeted to cell borders; other mutants showed variable cytoplasmic distributions. None of the mutants initially disrupted the localization of endogenous ZO-1. However, long-term stable expression of two of the N-terminal mutants resulted in a dramatic change in cell shape and patterns of gene expression. An elongated fibroblast-like shape replaced characteristic epithelial cobblestone morphology. In addition, vimentin and smooth muscle actin expression were up-regulated, although variable cytokeratin expression remained, suggesting a partial transformation to a mesenchymal cell type. Concomitant with the morphological change, the expression of the integral membrane tight junction protein occludin was significantly down-regulated. The localizations of endogenous ZO-1 and another family member, ZO-2, were disrupted. These findings suggest that ZO-1 may participate in regulation of cellular differentiation.

MeSH terms

  • Animals
  • Base Sequence
  • Cell Differentiation
  • Cell Line, Transformed
  • Epithelium, Corneal / cytology*
  • Epithelium, Corneal / metabolism
  • Epithelium, Corneal / pathology
  • Epitopes / genetics
  • Humans
  • Intercellular Junctions
  • Membrane Proteins / genetics*
  • Membrane Proteins / immunology
  • Membrane Proteins / metabolism
  • Mesoderm / cytology
  • Molecular Sequence Data
  • Mutation*
  • Occludin
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Phosphoproteins / genetics*
  • Phosphoproteins / immunology
  • Phosphoproteins / metabolism
  • Precipitin Tests
  • Rabbits
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Zonula Occludens-1 Protein
  • Zonula Occludens-2 Protein


  • Epitopes
  • Membrane Proteins
  • OCLN protein, human
  • Occludin
  • Peptide Fragments
  • Phosphoproteins
  • Recombinant Proteins
  • TJP1 protein, human
  • TJP2 protein, human
  • Zonula Occludens-1 Protein
  • Zonula Occludens-2 Protein