PGE₂promotes Ca²⁺-mediated epithelial barrier disruption through EP₁and EP₄receptors in Caco-2 cell monolayers

Abstract

We recently demonstrated that PGE2 induces the disruption of the intestinal epithelial barrier function. In the present study, our objectives were to study the role of PGE2 receptors (EP1-EP4) and the signaling pathways involved in this event. Paracellular permeability (PP) was assessed in differentiated Caco-2 cell cultures from D-mannitol fluxes and transepithelial electrical resistance (TER) in the presence of different PGE 2 receptor agonists (carbacyclin, sulprostone, butaprost, ONO-AE1-259, ONO-AE-248, GR63799, and ONO-AE1-329) and antagonists (ONO-8711, SC-19220, AH-6809, ONO-AE3-240, ONO-AE3-208, and AH-23848). The results indicate that EP1 and EP4 but not EP2 and EP3 might be involved in PP regulation. These effects were mediated through PLC-inositol trisphosphate (IP 3)-Ca 2ϩ and cAMP-PKA signaling pathways, respectively. We also observed an increase in intracellular Ca 2ϩ concentration ([Ca 2ϩ ]i) strengthened by cAMP formation indicating a cross talk interaction of these two pathways. Moreover, the participation of a conventional PKC isoform was shown. The results also indicate that the increase in PP may be correlated with the redistribution of occludin, zona occludens 1 (ZO-1), and the perijunctional actin ring together with an increase in myosin light chain kinase activity. Although the disruption of epithelial barrier function observed in inflammatory bowel disease (IBD) patients has been traditionally attributed to cytokines, the present study focused on the role of PGE2 in PP regulation, as mucosal levels of this eicosanoid are also increased in these inflammatory processes. paracellular permeability; intestine; tight junctions; eicosanoids; arachidonic acid cascade THE STRUCTURAL INTEGRITY OF the epithelium is maintained by three distinct adhesion systems: tight junctions (TJ), adherent junctions, and desmosomes. Of these, TJ are the most apical component and are the rate-limiting step for paracellular permeability (PP). In addition, TJ constitute the interface (fence) between apical and basolateral membrane domains (32). TJ are multiprotein complexes composed of transmembrane proteins associated with the cytoskeletal perijunctional ring of actin and myosin and with cytosolic proteins involved in cell signaling and vesicle trafficking. Five transmembrane proteins of the junctional complex have been identified in recent years: occludin, the claudin family, tricellulin, crumbs, and junctional adhesion molecules. These proteins are associated with a wide spectrum of cytosolic proteins, of which zona occludens (ZO) 1, ZO-2, ZO-3, AF6, and cingulin are described as forming the nexus with cytoskeletal proteins (42). PGE 2 is an inflammatory mediator that has pleiotropic effects on signal transduction and exerts its biological action through binding to four specific membrane receptor subtypes, EP 1 , EP 2 , EP 3 , and EP 4 , which are widely distributed and have different tissue expression. PGE 2 stimulation leads to activation of different G proteins, depending on the type of EP subtype engaged, i...

Role of arachidonic acid metabolites on the control of non-differentiated intestinal epithelial cell growth

“…This role of p38␣ in CREB phosphorylation was recently reported by Pham et al (2008) using angiotensin II stimulated rat intestinal epithelial cells. The role of AMPc-PKA has been described as a consequence of the increase in AMPc induced by PGE 2 in Caco-2 cell cultures (Rodríguez-Lagunas et al, 2010). However, in disagreement with Tessner et al (2004), we did not observe a role for AKT1/2 in cell signaling induced by PGE 2 .…”

“…Recently, we reported the immunolocalization of PGE2 receptors such as EP1 and EP4 in differentiated Caco-2 cells (Rodríguez-Lagunas et al, 2010). Our results show that SC 19220, an EP1 antagonist (Funk et al, 1993) and AH 23838, an EP4 antagonist (Nishigaki et al, 1995), inhibited Caco-2 proliferation ( Fig.…”

Parathyroid hormone (PTH) rapidly enhances CFTR-mediated HCO3−secretion in intestinal epithelium-like Caco-2 monolayer: a novel ion regulatory action of PTH

“…This phenomenon was usually explained by the increased opening of ion channels or increased activities of transcellular ion transporters (40). Although some cAMP-dependent mediators, such as prostaglandin E 2 , were capable of altering the paracellular permeability (47), the absence of changes in R p and transepithelial mannitol transport suggested that paracellular pathway was not involved. If paracellular ion transport was increased by PTH, the charge-and/or size-selective properties of the tight junction would have been changed (58), thereby leading to a decrease in R p and/or an increase in mannitol flux.…”

Induction of Increased Permeability of Polarized Enterocyte Monolayers by Enterotoxigenic Escherichia coli Heat-Labile Enterotoxin

“…[22][23][24] The interface between LT-dependent ADP ribosylation and tight junction signaling is the subject of ongoing work in our laboratory.…”