AGR2 ameliorates tumor necrosis factor-α-induced epithelial barrier dysfunction via suppression of NF-κB p65-mediated MLCK/p-MLC pathway activation.
Intestinal epithelial barrier dysfunction plays a critical role in the pathogenesis of inflammatory bowel disease (IBD). Anterior gradient protein 2 homologue (AGR2) assists in maintaining intestinal homeostasis in dextran sulphate sodium-induced mouse ileocolitis; however, it is unclear whether it modulates intestinal barrier function. Our study aimed to investigate the protective role of AGR2 in tumor necrosis factor (TNF)-α-induced intestinal epithelial barrier injury. Caco-2 cell monolayers were pre-transfected with an AGR2 plasmid and then exposed to TNF-α. Epithelial permeability was assessed by detecting transepithelial electrical resistance and fluorescein isothiocyanate-dextran (40 kDa) flux. The protein expression levels of zonula occludens-1 (ZO-1), occludin, claudin-1, myosin light chain kinase (MLCK)/p-MLC, and nuclear factor (NF)-κB p65 were determined by western blotting. In addition, the cellular distributions of ZO-1, occludin, F-actin, and NF-κB p65 were evaluated by immunofluorescence staining. The results showed that the AGR2 mRNA and protein expression levels were both decreased in the Caco-2 cell monolayers, while AGR2 overexpression significantly ameliorated TNF-α-induced epithelial barrier hyperpermeability, increased the expression of tight junction (TJ) proteins and stabilized the cytoskeletal structure. Furthermore, AGR2 inhibited the changes in MLCK, MLC and p-MLC expression in response to TNF-α stimulation. Collectively, our study suggests that AGR2 inhibits TNF-α‑induced Caco-2 cell hyperpermeability by regulating TJ and that this protective mechanism may be promoted by inhibition of NF-κB p65-mediated activation of the MLCK/p-MLC signaling pathway.
Department of Paediatrics, China Medical University Affiliated with Shengjing Hospital, Shenyang, Liaoning 110004, P.R. China.
Xiaolin
X
Ye
Department of Paediatrics, China Medical University Affiliated with Shengjing Hospital, Shenyang, Liaoning 110004, P.R. China.
Mei
M
Sun
D000199:Actins / Q000378:metabolism; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability / Q000235:genetics; D062445:Claudin-1 / Q000378:metabolism; D004847:Epithelial Cells / Q000382:microbiology; D015870:Gene Expression; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D009088:Mucoproteins; D018994:Myosin Light Chains / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism*; D015513:Oncogene Proteins; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D062725:Tight Junction Proteins / Q000235:genetics / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein / Q000378:metabolism
C502296:AGR2 protein, human; D000199:Actins; D062445:Claudin-1; D009088:Mucoproteins; D018994:Myosin Light Chains; D015513:Oncogene Proteins; D011506:Proteins; C569042:TJP1 protein, human; D062725:Tight Junction Proteins; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D062826:Zonula Occludens-1 Protein; D009219:Myosin-Light-Chain Kinase