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Epac1 Regulates Intestinal Epithelial Barrier Function by Recruiting JAM‐A via RAP2C‐TNIK Signaling Pathway
Author(s) -
Sheikh Irshad,
Kazi Mirajul
Publication year - 2015
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.29.1_supplement.673.3
Subject(s) - microbiology and biotechnology , tight junction , occludin , paracellular transport , chemistry , barrier function , signal transduction , forskolin , biology , biochemistry , receptor , membrane , permeability (electromagnetism)
cAMP is one of the most potent signaling molecule to stabilize epithelial barrier function. However, the regulatory mechanism by novel cAMP effector, E xchange P rotein directly A ctivated by c AMP (Epac1) is unknown. Incubating T84 cells with Epac1 agonist 8‐pCPT‐2′‐O‐Me‐cAMP or cAMP elevating agent forskolin (FSK) in presence of PKA inhibitor H89, caused transient reduction of Transepithelial Electrical Resistance (TER) that restored to normal value after short period of time while FSK alone drastically lower TER and disrupt TJ integrity. T84 cells with silenced Epac1 protein (Epac1KDT84) had reduced TER, increased paracellular flux of 4kDa FITC‐dextran and decreased paracellular permeability of Na + . Confocal study revealed mislocalization of major TJ protein, Junctional Adhesion Molecule‐A (JAM‐A) in Epac1KDT84 cells while no such change was observed in other TJ protein such as occludin. Surface biotinylation assay showed reduced band intensity of JAM‐A in Epac1KDT84 cells than in T84 cells. Silencing downstream Epac1 effector Rap2C and TNIK had similar changes in TER and flux as observed in Epac1KDT84 cells. Preincubating T84 cells with recycling endosome inhibitor, primaquine caused reduced surface expression of JAM‐A which was not observed in Epac1KDT84 cells. Shigella flexneri 2a infected T84 cells showed high expression of Epac1 protein while invasion rate of Shigella significantly increased in Epac1KDT84 cells. We conclude that Epac1 regulates intestinal barrier function by recruiting JAM‐A at the level of tight junction by a novel Rap2C‐TNIK signaling pathway which may have therapeutic value in treating inflammatory diarrhea.