title: PI3K signaling is required for prostaglandin-induced mucosal recovery in ischemia-injured porcine ileum.
abstract: We have previously shown that PGE(2) and PGI(2) induce recovery of transepithelial resistance (TER) in ischemia-injured porcine ileal mucosa, associated with initial increases in Cl(-) secretion. We believe that the latter generates an osmotic gradient that stimulates resealing of tight junctions. Because of evidence implicating phosphatidylinositol 3-kinase (PI3K) in regulating tight junction assembly, we postulated that this signaling pathway is involved in PG-induced mucosal recovery. Porcine ileum was subjected to 45 min of ischemia, after which TER was monitored for a 180-min recovery period. Endogenous PG production was inhibited with indomethacin (5 microM). PGE(2) (1 microM) and PGI(2) (1 microM) stimulated recovery of TER, which was inhibited by serosal application of the osmotic agent urea (300 mosmol/kgH(2)O). The PI3K inhibitor wortmannin (10 nM) blocked recovery of TER in response to PGs or mucosal urea. Immunofluorescence imaging of recovering epithelium revealed that PGs restored occludin and zonula occludens-1 distribution to interepithelial junctions, and this pattern was disrupted by pretreatment with wortmannin. These experiments suggest that PGs stimulate recovery of paracellular resistance via a mechanism involving transepithelial osmotic gradients and PI3K-dependent restoration of tight junction protein distribution.
authors.affiliation: Department of Clinical Sciences, North Carolina State University, Raleigh 27606, USA.
authors.forename: Dianne
authors.initials: D
authors.lastname: Little
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Dean
authors.forename: Karen M
authors.initials: KM
authors.lastname: Young
authors.forename: Shaun A
authors.initials: SA
authors.lastname: McKane
authors.forename: Linda D
authors.initials: LD
authors.lastname: Martin
authors.forename: Samuel L
authors.initials: SL
authors.lastname: Jones
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Blikslager
mesh_terms: D015064:16,16-Dimethylprostaglandin E2 / Q000494:pharmacology; D000818:Animals; D000897:Anti-Ulcer Agents / Q000494:pharmacology; D017097:Electric Impedance; D011464:Epoprostenol / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D006801:Humans; D007082:Ileum / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000648:ultrastructure; D007511:Ischemia / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D062793:Occludin; D009997:Osmotic Pressure; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D020127:Recovery of Function / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013552:Swine; D019108:Tight Junctions / Q000201:enzymology; D014508:Urea / Q000494:pharmacology; D062826:Zonula Occludens-1 Protein
chemical_list: D000897:Anti-Ulcer Agents; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; D010975:Platelet Aggregation Inhibitors; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; C026678:carboprostacyclin; D014508:Urea; D011464:Epoprostenol; D019869:Phosphatidylinositol 3-Kinases; D015064:16,16-Dimethylprostaglandin E2