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Christian Piehl Jörg Piontek Jimmi Cording Hartwig Wolburg Ingolf E. Blasig 《Cellular and molecular life sciences : CMLS》2010,67(12):2131-2140
Tight junctions control paracellular permeability. Here, we analyzed the impact of residues in the second extracellular loop
(ECL2) of mouse claudin-5 on paracellular permeability. Stable expression of claudin-5wild type in MDCK-II cells—but not that of mutants R145A, Y148A, Y158A or E159Q—increased transepithelial electrical resistance and
decreased fluorescein permeation. Expression of claudin-5Y148A, Y158A or E159Q enhanced permeability of FITC-dextran10 kDa, which was unchanged in cells expressing claudin-5wild type or claudin-5R145A. In contrast, targeting to tight junctions, strand morphology and tight junction assembly were unchanged. It is concluded
that R145 is unessential for trans-interaction of claudin-5, but necessary for tightening against small solutes and ions. The highly conserved residues Y148,
Y158 and E159 in ECL2 of claudin-5 contribute to homo- and/or heterophilic trans-interaction between classic claudins and thereby tighten the paracellular space against ions, small and large molecules.
These results provide novel insights into the molecular function of tight junctions. 相似文献
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Piontek J Fritzsche S Cording J Richter S Hartwig J Walter M Yu D Turner JR Gehring C Rahn HP Wolburg H Blasig IE 《Cellular and molecular life sciences : CMLS》2011,68(23):3903-3918
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. 相似文献
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Julie K. Westphal Max J. Dörfel Susanne M. Krug Jimmi D. Cording Jörg Piontek Ingolf E. Blasig Rudolf Tauber Michael Fromm Otmar Huber 《Cellular and molecular life sciences : CMLS》2010,67(12):2057-2068
Sealing of the paracellular cleft by tight junctions is of central importance for epithelia and endothelia to function as
efficient barriers between the extracellular space and the inner milieu. Occludin and claudins represent the major tight junction
components involved in establishing this barrier function. A special situation emerges at sites where three cells join together.
Tricellulin, a recently identified tetraspan protein concentrated at tricellular contacts, was reported to organize tricellular
as well as bicellular tight junctions. Here we show that in MDCK cells, the tricellulin C-terminus is important for the basolateral
translocation of tricellulin, whereas the N-terminal domain appears to be involved in directing tricellulin to tricellular
contacts. In this respect, identification of homomeric tricellulin-tricellulin and of heteromeric tricellulin-occludin complexes
extends a previously published model and suggests that tricellulin and occludin are transported together to the edges of elongating
bicellular junctions and get separated when tricellular contacts are formed. 相似文献
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