title: Cyclic AMP-dependent protein kinase A negatively modulates adherens junction integrity and differentiation of intestinal epithelial cells.
abstract: Intestinal epithelial cell differentiation is a complex process in which many different signaling pathways are likely involved. An increase in the intracellular levels of cyclic AMP (cAMP) has been shown to inhibit enterocyte differentiation; however, the mechanisms through which cAMP/PKA signaling modulates differentiation of human intestinal epithelial cells are still not well understood. Herein, we report that: (1) treatment of Caco-2/15 cells with 8Br-cAMP repressed sucrase-isomaltase and villin protein expression and strongly attenuated morphological differentiation of enterocyte-like features in Caco-2/15 such as epithelial cell polarity and brush border formation; (2) treatment of confluent Caco-2/15 cells with 8Br-cAMP led to a strong decrease in F-actin localized at cell-cell contact sites along with a reduced amount of E-cadherin and catenins, but not of ZO-1, at cell-cell interfaces concomitant with a decreased association of these proteins with the actin cytoskeleton; (3) inhibition of PKA by H89 prevented disruption of adherens junctions by extracellular calcium depletion; (4) treatment of Caco-2/15 cells with 8Br-cAMP prevented the recruitment and activation of p85/PI-3K to E-cadherin-mediated cell-cell contacts, an important event in the assembly of adherens junctions and differentiation of these cells; (5) E-cadherin appears to be phosphorylated on serine in vivo in a PKA-dependent mechanism.
  
  
  CONCLUSIONS
  Our studies show that cAMP/PKA signaling negatively regulates adherens junction integrity as well as morphological and functional differentiation of intestinal epithelial cells.
authors.affiliation: CIHR Group on Functional Development and Physiopathology of the Digestive Tract, Département d'Anatomie et Biologie Cellulaire, Faculty of Medicine, University of Sherbrooke, QC, Canada.
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Boucher
authors.forename: Patrick
authors.initials: P
authors.lastname: Laprise
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rivard
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D022005:Adherens Junctions / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D018938:Caco-2 Cells; D015820:Cadherins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D015536:Down-Regulation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000201:enzymology* / Q000648:ultrastructure; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000254:growth & development* / Q000648:ultrastructure; D008840:Microfilament Proteins / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D008871:Microvilli / Q000378:metabolism / Q000648:ultrastructure; D013394:Sucrase-Isomaltase Complex / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D051178:alpha Catenin; D051176:beta Catenin
chemical_list: D000199:Actins; C495273:CTNNA1 protein, human; C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; C094556:Ecm1 protein, mouse; D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D008840:Microfilament Proteins; D015534:Trans-Activators; D051178:alpha Catenin; D051176:beta Catenin; C026615:villin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D013394:Sucrase-Isomaltase Complex; D002118:Calcium