The first two authors contributed equally to this work.
AMP-18 facilitates assembly and stabilization of tight junctions to protect the colonic mucosal barrier†
Article first published online: 23 JAN 2012
Copyright © 2012 Crohn's & Colitis Foundation of America, Inc.
Inflammatory Bowel Diseases
Volume 18, Issue 9, pages 1749–1759, September 2012
How to Cite
Chen, P., Kartha, S., Bissonnette, M., Hart, J. and Toback, F. G. (2012), AMP-18 facilitates assembly and stabilization of tight junctions to protect the colonic mucosal barrier. Inflamm Bowel Dis, 18: 1749–1759. doi: 10.1002/ibd.22886
Supported by grants from the Crohn's & Colitis Foundation of America (to F.G.T.); National Institutes of Health grants R21 DE018811 (to F.G.T.), P30DK42086 (NIDDK, Digestive Diseases Research Core Center), CA036745 (to M.B.); the Samuel Freedman Research Laboratories for Gastrointestinal Cancer Research and Department of Pathology Research Core at the University of Chicago (to J.H.).
- Issue published online: 9 AUG 2012
- Article first published online: 23 JAN 2012
- Manuscript Accepted: 28 DEC 2011
- Manuscript Received: 9 DEC 2011
- antrum mucosal protein (AMP)-18;
- tight junctions;
- p38 mitogen activated protein kinase;
Inflammatory bowel disease (IBD) is characterized by an injured epithelium. Development of agents that could enhance mucosal healing is a major goal in IBD therapeutics. The 18-kDa antrum mucosal protein (AMP-18) and a 21-mer peptide derived from AMP-18 stimulate accumulation of tight junction (TJ) proteins in cultured epithelial cells and mouse colonic mucosa to protect the mucosal barrier, suggesting it might be a useful agent to treat IBD.
We searched for molecular mechanisms by which AMP peptide or recombinant AMP-18 act on TJs in intact cell monolayers, or those disrupted by low-calcium medium. Roles of the p38 mitogen-activated protein kinase (MAPK) / heat shock protein (hsp)25 pathway and PKCζ were investigated by immunoblotting and confocal microscopy.
AMP peptide activated p38 MAPK, which subsequently phosphorylated hsp25. Accumulated phospho-hsp25 was associated with perijunctional actin. AMP-18 also induced rapid phosphorylation of PKCζ and its colocalization with perijunctional actin in Caco2/bbe cells, which was accompanied by translocation and formation of complexes of “polarity proteins” in the TJ-containing detergent-insoluble fraction. Treatment with AMP-18 also stimulated accumulation of ZO-1, ZO-2, and JAM-A in nascent TJs known to associate with the multimeric p-PKCζ/Par6/ Cdc42/ECT2·GTP/Par3 polarity protein complex.
AMP-18 facilitates translocation and assembly of multiple proteins into TJs and their association with and subsequent stabilization of the actin filament network. We speculate that improved barrier function induced by AMP-18 is mediated by enhanced TJ assembly. Thus, AMP-18 may provide a promising lead to develop agents effective in healing injured colonic epithelium in IBD. (Inflamm Bowel Dis 2012;)