AMP-18 facilitates assembly and stabilization of tight junctions to protect the colonic mucosal barrier

Inflamm Bowel Dis. 2012 Sep;18(9):1749-59. doi: 10.1002/ibd.22886. Epub 2012 Jan 23.


Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caco-2 Cells
  • Calcium / metabolism
  • Cells, Cultured
  • Colitis / chemically induced
  • Colitis / metabolism
  • Colitis / prevention & control*
  • Colon / injuries
  • Colon / metabolism
  • Colon / pathology*
  • Dextran Sulfate / toxicity
  • Fluorescent Antibody Technique, Indirect
  • HSP27 Heat-Shock Proteins / metabolism
  • Heat-Shock Proteins
  • Humans
  • Intestinal Mucosa / injuries
  • Intestinal Mucosa / metabolism
  • Intestinal Mucosa / pathology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Molecular Chaperones
  • Peptide Fragments / metabolism*
  • Peptide Hormones / metabolism*
  • Phosphorylation
  • Protein Kinase C / metabolism
  • Rats
  • Tight Junctions / physiology*
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • GKN1 protein, human
  • HSP27 Heat-Shock Proteins
  • HSPB1 protein, human
  • Heat-Shock Proteins
  • Molecular Chaperones
  • Peptide Fragments
  • Peptide Hormones
  • Dextran Sulfate
  • protein kinase C zeta
  • Protein Kinase C
  • p38 Mitogen-Activated Protein Kinases
  • Calcium