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Serine Proteases Decrease Intestinal Epithelial Permeability By A PKCζ‐mediated mechanism
Author(s) -
Swystun Veronica,
MacNaughton Wallace
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a191-d
Subject(s) - proteases , protein kinase c , trypsin , phospholipase c , microbiology and biotechnology , chemistry , paracellular transport , elastase , barrier function , signal transduction , intestinal epithelium , protease activated receptor , biochemistry , epithelium , biology , enzyme , permeability (electromagnetism) , immunology , platelet , genetics , thrombin , membrane
The transport of ions and the permeability to macromolecules across the epithelium regulates fluid balance in the gastrointestinal tract. The digestive serine proteases trypsin, elastase and chymotrypsin decrease the paracellular permeability of intestinal epithelial cells to Na + , Cl − and 3000MW dextran. We investigated the mechanisms involved in this possible barrier‐protective effect. Changes in transepithelial electrical resistance (R TE ) across intestinal epithelial cells were measured in Ussing chambers, employing several activators and inhibitors of signaling pathways. Activators of protease activated receptors (PARs)‐1,‐2 and ‐4 were without effect. Inhibitors of phosphoinositol‐specific phospholipase‐C (PLC), U73122 (50μM) and ET‐18‐OCH 3 (10μM), attenuated the trypsin‐induced increase in R TE by 92 ± 33 and 78 ± 24 % respectively. Protein kinase C enzymes are downstream effectors of PLC. Activation of typical and novel PKC isoforms with PMA (1μM) did not increase R TE and two broad spectrum inhibitors of PKCs did not inhibit the trypsin‐induced increase in R TE . However, an inhibitor specific for the atypical isoform PKCζ significantly decreased baseline R TE and prevented the trypsin‐induced increase in R TE (786 ± 118 vs.138 ± 36 Ω x cm 2 ; n=18 and 9; p<0.01). In accordance with the Ca 2+ ‐independence of PKCζ activation, pre‐treatment of the epithelial cells with the Ca 2+ ‐modulating agents BAPTA‐AM or 2‐APB did not affect the trypsin‐mediated increase in R TE . These data indicate a novel role for digestive serine proteases in the regulation of intestinal epithelial barrier function. The effect is independent of PARs and is mediated by PLC and PKCζ. Supported by CIHR/CAG‐CCFC