Claudin-8 interacts with multi-PDZ domain protein 1 (MUPP1) and reduces paracellular conductance in epithelial cells

Cell Mol Biol (Noisy-le-grand). 2003 Feb;49(1):13-21.


The claudin family is a set of integral membrane proteins found at cell-cell interactions in tight junctions. To identify proteins that interact with claudin-8, we used the yeast two-hybrid system to search for binding partners. Using the C-terminal 37 amino acids of claudin-8 as bait, we screened a human kidney cDNA library and identified multi-PDZ domain protein 1 (MUPP1) as a claudin-8 binding protein. MUPP1 contains 13 PDZ domains and binds to claudin-8 though its PDZ9 domain. When MDCK cells were transfected with epitope-tagged claudin-8 or MUPP1, both molecules were concentrated at cell-cell junctions. The interaction of claudin-8 and MUPP1 in vivo was confirmed by co-immunolocalization and co-immunoprecipitation in MDCK cells. Expression of claudin-8-myc increased transepithelial electrical resistance (TER) and reduced paracellular flux using FITC-dextran as a tracer. Over-expression of FLAG-MUPP1 in MDCK cells also reduced the epithelial paracelhular conductance. Our results indicate that claudin-8 and MUPP1 interact in tight junctions of epithelial cells and are involved in the tight junction barrier function.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Claudins
  • Epithelial Cells / metabolism*
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Transduction, Genetic
  • Two-Hybrid System Techniques


  • Carrier Proteins
  • Claudins
  • MPDZ protein, human
  • Membrane Proteins
  • Mpdz protein, mouse
  • claudin 8