title: Butyrate enhances the intestinal barrier by facilitating tight junction assembly via activation of AMP-activated protein kinase in Caco-2 cell monolayers.
abstract: Butyrate, one of the SCFA, promotes the development of the intestinal barrier. However, the molecular mechanisms underlying the butyrate regulation of the intestinal barrier are unknown. To test the hypothesis that the effect of butyrate on the intestinal barrier is mediated by the regulation of the assembly of tight junctions involving the activation of the AMP-activated protein kinase (AMPK), we determined the effect of butyrate on the intestinal barrier by measuring the transepithelial electrical resistance (TER) and inulin permeability in a Caco-2 cell monolayer model. We further used a calcium switch assay to study the assembly of epithelial tight junctions and determined the effect of butyrate on the assembly of epithelial tight junctions and AMPK activity. We demonstrated that the butyrate treatment increased AMPK activity and accelerated the assembly of tight junctions as shown by the reorganization of tight junction proteins, as well as the development of TER. AMPK activity was also upregulated by butyrate during calcium switch-induced tight junction assembly. Compound C, a specific AMPK inhibitor, inhibited the butyrate-induced activation of AMPK. The facilitating effect of butyrate on the increases in TER in standard culture media, as well as after calcium switch, was abolished by compound C. We conclude that butyrate enhances the intestinal barrier by regulating the assembly of tight junctions. This dynamic process is mediated by the activation of AMPK. These results suggest an intriguing link between SCFA and the intracellular energy sensor for the development of the intestinal barrier.
authors.affiliation: Department of Pediatrics, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
authors.forename: Luying
authors.initials: L
authors.lastname: Peng
authors.forename: Zhong-Rong
authors.initials: ZR
authors.lastname: Li
authors.forename: Robert S
authors.initials: RS
authors.lastname: Green
authors.forename: Ian R
authors.initials: IR
authors.lastname: Holzman
authors.forename: Jing
authors.initials: J
authors.lastname: Lin
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D002087:Butyrates / Q000378:metabolism*; D018938:Caco-2 Cells; D017097:Electric Impedance; D004848:Epithelium / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D007444:Inulin / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D010539:Permeability / Q000187:drug effects*; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000378:metabolism; D019108:Tight Junctions / Q000201:enzymology / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D002087:Butyrates; D008565:Membrane Proteins; D047428:Protein Kinase Inhibitors; D007444:Inulin; D055372:AMP-Activated Protein Kinases