title: Transforming growth factor-β, a whey protein component, strengthens the intestinal barrier by upregulating claudin-4 in HT-29/B6 cells.
abstract: TGFβ (isoforms 1-3) has barrier-protective effects in the intestine. The mechanisms involved in regulating tight junction protein expression are poorly understood. The aim of this study was to elucidate TGFβ-dependent protective effects with special attention to promoter regulation of tight junction proteins using the HT-29/B6 cell model. In addition, the effects of whey protein concentrate 1 (WPC1), a natural source of TGFβ in human nutrition, were examined. For this purpose, the claudin-4 promoter was cloned and tested for its activity. It exhibited transactivation in response to TGFβ1, which was intensified when Smad-4 was cotransfected, indicating a Smad-4-dependent regulatory component. Shortening and mutation of the promoter altered and attenuated this effect. WPC1 induced an increase in the claudin-4 protein level and resistance of HT-29/B6 cell monolayers. Anti-TGFβ(1-3) antibodies blocked these whey protein effects, suggesting that a main part of this function was mediated through TGFβ. This effect was observed on intact monolayers as well as when barrier function was impaired by preexposure to IFNγ. In conclusion, TGFβ1 affects claudin-4 gene expression via Smad-4-dependent and -independent transcriptional regulation, resulting in barrier protection, a cytokine effect that is also found in whey protein concentrates used in enteral nutrition.
authors: Department of Gastroenterology, Charité, Campus Benjamin Franklin, Berlin 12200, Germany.
authors: Nina A
authors: NA
authors: Hering
authors: Susanne
authors: S
authors: Andres
authors: Anja
authors: A
authors: Fromm
authors: Eric A
authors: EA
authors: van Tol
authors: Maren
authors: M
authors: Amasheh
authors: Joachim
authors: J
authors: Mankertz
authors: Michael
authors: M
authors: Fromm
authors: Joerg D
authors: JD
authors: Schulzke
mesh_terms: D000818:Animals; D002417:Cattle; D062506:Claudin-4; D017097:Electric Impedance; D055951:Functional Food; D017930:Genes, Reporter; D019073:HT29 Cells; D006801:Humans; D007371:Interferon-gamma / Q000633:toxicity; D007413:Intestinal Mucosa / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008894:Milk Proteins / Q000378:metabolism* / Q000627:therapeutic use; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011401:Promoter Regions, Genetic; D020011:Protective Agents / Q000378:metabolism / Q000627:therapeutic use; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000378:metabolism; D011994:Recombinant Proteins; D015398:Signal Transduction; D051901:Smad4 Protein / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000627:therapeutic use; D015854:Up-Regulation; D000067816:Whey Proteins
chemical_list: C568157:CLDN4 protein, human; D062506:Claudin-4; D008565:Membrane Proteins; D008894:Milk Proteins; D020011:Protective Agents; D020033:Protein Isoforms; D011994:Recombinant Proteins; C497796:SMAD4 protein, human; D051901:Smad4 Protein; D016212:Transforming Growth Factor beta; D000067816:Whey Proteins; D007371:Interferon-gamma