Claudin-1 contributes to the epithelial barrier function in MDCK cells

Eur J Cell Biol. 1999 Dec;78(12):849-55. doi: 10.1016/S0171-9335(99)80086-7.


Tight junctions (TJs) create a paracellular permeability barrier and also act as a fence preventing intermixing of proteins and lipids between the apical and basolateral plasma membranes. Recently, claudin-1 has been identified as an integral membrane protein localizing at TJs, and introduced claudin-1 can form TJ-like networks in fibroblasts. To investigate the function of claudin-1, MDCK cells were transfected with a mammalian expression vector containing myc-tagged mouse claudin-1, and four stable clones were obtained. The myc-tagged claudin-1 precisely colocalized with both occludin and ZO-1 at cell-cell contact sites, indicating that exogenous claudin-1 was properly targeted to the TJs. Immunoblot analysis revealed that overexpression of claudin-1 increased expression of ZO-1 but not of occludin or ZO-2. The barrier functions of these cells were evaluated by transepithelial electrical resistance (TER) and paracellular flux. Claudin-1-expressing cells exhibited about four times higher TER than wild-type MDCK cells. Consistent with the increase of TER, the cells overexpressing claudin-1 showed reduced paracellular flux, estimated at 4 and 40 kD FITC-dextrans. These results suggest that claudin-1 is involved in the barrier function at TJs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport
  • Cell Communication / physiology
  • Cell Line
  • Cell Membrane Permeability / physiology
  • Claudin-1
  • Dogs
  • Epithelial Cells / physiology*
  • Epithelial Cells / ultrastructure
  • Membrane Proteins / physiology*
  • Mice
  • Tight Junctions / physiology


  • Claudin-1
  • Cldn1 protein, mouse
  • Membrane Proteins