title: Elucidating the principles of the molecular organization of heteropolymeric tight junction strands.
abstract: Paracellular barrier properties of tissues are mainly determined by the composition of claudin heteropolymers. To analyze the molecular organization of tight junctions (TJ), we investigated the ability of claudins (Cld) to form homo- and heteromers. Cld1, -2, -3, -5, and -12 expressed in cerebral barriers were investigated. TJ-strands were reconstituted by claudin-transfection of HEK293-cells. cis-Interactions and/or spatial proximity were analyzed by fluorescence resonance energy transfer inside and outside of strands and ranked: Cld5/Cld5 > Cld5/Cld1 > Cld3/Cld1 > Cld3/Cld3 > Cld3/Cld5, no Cld3/Cld2. Classic Cld1, -3, and -5 but not non-classic Cld12 showed homophilic trans-interaction. Freeze-fracture electron microscopy revealed that, in contrast to classic claudins, YFP-tagged Cld12 does not form homopolymers. Heterophilic trans-interactions were analyzed in cocultures of differently monotransfected cells. trans-Interaction of Cld3/Cld5 was less pronounced than that of Cld3/Cld1, Cld5/Cld1, Cld5/Cld5 or Cld3/Cld3. The barrier function of reconstituted TJ-strands was demonstrated by a novel imaging assay. A model of the molecular organization of TJ was generated.
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany. piontek@fmp-berlin.de
authors.forename: Jörg
authors.initials: J
authors.lastname: Piontek
authors.forename: Susanne
authors.initials: S
authors.lastname: Fritzsche
authors.forename: Jimmi
authors.initials: J
authors.lastname: Cording
authors.forename: Sandra
authors.initials: S
authors.lastname: Richter
authors.forename: Jens
authors.initials: J
authors.lastname: Hartwig
authors.forename: Maria
authors.initials: M
authors.lastname: Walter
authors.forename: Dan
authors.initials: D
authors.lastname: Yu
authors.forename: Jerrold R
authors.initials: JR
authors.lastname: Turner
authors.forename: Claudia
authors.initials: C
authors.lastname: Gehring
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Rahn
authors.forename: Hartwig
authors.initials: H
authors.lastname: Wolburg
authors.forename: Ingolf E
authors.initials: IE
authors.lastname: Blasig
mesh_terms: D001812:Blood-Brain Barrier / Q000166:cytology / Q000378:metabolism; D002478:Cells, Cultured; D057167:Claudins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D019108:Tight Junctions / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D057167:Claudins