title: Claudin-8 interacts with multi-PDZ domain protein 1 (MUPP1) and reduces paracellular conductance in epithelial cells.
abstract: 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.
authors.affiliation: Department of Anatomy and Cell Biology, East Carolina University, Brody School of Medicine, Greenville, NC 27858, USA.
authors.forename: B
authors.initials: B
authors.lastname: Jeansonne
authors.forename: Q
authors.initials: Q
authors.lastname: Lu
authors.forename: D A
authors.initials: DA
authors.lastname: Goodenough
authors.forename: Y H
authors.initials: YH
authors.lastname: Chen
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D057167:Claudins; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D014161:Transduction, Genetic; D020798:Two-Hybrid System Techniques
chemical_list: D002352:Carrier Proteins; D057167:Claudins; C111442:MPDZ protein, human; D008565:Membrane Proteins; C491750:Mpdz protein, mouse; C502011:claudin 8