Open AccessAMP‐18 facilitates assembly and stabilization of tight junctions to protect the colonic mucosal barrier
Author(s) -
Chen Peili,
Kartha Sreedharan,
Bissonnette Marc,
Hart John,
Toback F. Gary
Publication year - 2012
Publication title -
inflammatory bowel diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.932
H-Index - 146
eISSN - 1536-4844
pISSN - 1078-0998
DOI - 10.1002/ibd.22886
Subject(s) - tight junction , microbiology and biotechnology , cdc42 , barrier function , protein kinase a , p38 mitogen activated protein kinases , actin , colocalization , actin cytoskeleton , chemistry , protein kinase c , cytoskeleton , intestinal mucosa , phosphorylation , biology , biochemistry , cell , medicine
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. (Inflamm Bowel Dis 2012;)