title: TNFalpha up-regulates claudin-2 expression in epithelial HT-29/B6 cells via phosphatidylinositol-3-kinase signaling.
abstract: Our aim has been to characterize the molecular mechanisms regulating the expression of the channel-forming tight-junctional protein claudin-2 in response to the pro-inflammatory cytokine tumor necrosis factor-alpha (TNFalpha), which is elevated, for example, in active Crohn's disease. TNFalpha caused an 89% decrease of the paracellular resistance in colonic HT-29/B6 cells, whereas transcellular resistance was unaltered. The claudin-2 protein level was increased by TNFalpha without changes in subcellular tight-junctional protein localization as revealed by confocal laser scanning microscopy. Enhanced gene expression was identified as the source of this increase, since claudin-2-specific mRNA and promoter activity was elevated, whereas mRNA stability remained unaltered. Specific inhibitors and phospho-specific antibodies revealed that the increased gene expression of claudin-2 after TNFalpha treatment was mediated by the phosphatidylinositol-3-kinase pathway. Thus, the up-regulation of claudin-2 by TNFalpha is attributable to the regulation of the expression of the gene, as a result of which epithelial barrier function is disturbed, for example, during chronic intestinal inflammation.
authors.affiliation: Department of Gastroenterology, Charité, Campus Benjamin Franklin, Hindenburgdamm 30, 12200, Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Mankertz
authors.forename: M
authors.initials: M
authors.lastname: Amasheh
authors.forename: S M
authors.initials: SM
authors.lastname: Krug
authors.forename: A
authors.initials: A
authors.lastname: Fromm
authors.forename: S
authors.initials: S
authors.lastname: Amasheh
authors.forename: B
authors.initials: B
authors.lastname: Hillenbrand
authors.forename: S
authors.initials: S
authors.lastname: Tavalali
authors.forename: M
authors.initials: M
authors.lastname: Fromm
authors.forename: J D
authors.initials: JD
authors.lastname: Schulzke
mesh_terms: D002867:Chromones / Q000494:pharmacology; D057167:Claudins; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019073:HT29 Cells; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D015398:Signal Transduction / Q000187:drug effects; D019108:Tight Junctions / Q000235:genetics / Q000378:metabolism; D014018:Tissue Distribution; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D002867:Chromones; D057167:Claudins; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; C491875:CLDN2 protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one