Phosphatidylinositol 3-kinase-dependent pathways oppose fas-induced apoptosis and limit chloride secretion in human intestinal epithelial cells: Implications for inflammatory diarrheal states

Maria T Abreu, Elizabeth T. Arnold, Jimmy Y C Chow, Kim E. Barrett

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The epithelial lining of the intestine serves as a barrier to lumenal bacteria and can be compromised by pathologic Fas-mediated epithelial apoptosis. Phosphatidylinositol (PI)3-kinase signaling has been described to limit apoptosis in other systems. We hypothesized that PI3-kinase-dependent pathways regulate Fas-mediated apoptosis and barrier function in intestiynal epithelial cells (IEC). IEC lines (HT-29 and T84) were exposed to agonist anti-Fas antibody in the presence or absence of chemical inhibitors of PI3-kinase (LY294002 and wortmannin). Apoptosis, barrier function, changes in short circuit current (ΔIsc), and expression of adhesion molecules were assessed. Inhibition of PI3-kinase strongly sensitized IEC to Fas-mediated apoptosis. Expression of constitutively active Akt, a principal downstream effector of the PI3-kinase pathway, protected against Fas-mediated apoptosis to an extent that was comparable with expression of a genetic caspase inhibitor, p35. PI3-kinase inhibition sensitized to apoptosis by increasing and accelerating Fas-mediated caspase activation. Inhibition of PI3-kinase combined with cross-linking Fas was associated with increased permeability to molecules that were <400 Da but not those that were >3,000 Da. Inhibition of PI3-kinase resulted in chloride secretion that was augmented by cross-linking Fas. Confocal analyses revealed polymerization of actin and maintenance of epithelial cell adhesion molecule-mediated interactions in monolayers exposed to anti-Fas antibody in the context of PI3-kinase inhibition. PI3-kinase-dependent pathways, especially Akt, protect IEC against Fas-mediated apoptosis. Inhibition of PI3-kinase in the context of Fas signaling results in increased chloride secretion and barrier dysfunction. These findings suggest that agonists of PI3-kinase such as growth factors may have a dual effect on intestinal inflammation by protecting epithelial cells against immune-mediated apoptosis and limiting chloride secretory diarrhea.

Original languageEnglish
Pages (from-to)47563-47574
Number of pages12
JournalJournal of Biological Chemistry
Volume276
Issue number50
DOIs
StatePublished - Dec 14 2001
Externally publishedYes

Fingerprint

Phosphatidylinositol 3-Kinase
Phosphatidylinositol 3-Kinases
Chlorides
Epithelial Cells
Apoptosis
Anti-Idiotypic Antibodies
2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
Molecules
Caspase Inhibitors
Antibodies
Cell Adhesion Molecules
Caspases
Linings
Polymerization
Short circuit currents
Intestines
Actins
Diarrhea
Monolayers
Permeability

ASJC Scopus subject areas

  • Biochemistry

Cite this

Phosphatidylinositol 3-kinase-dependent pathways oppose fas-induced apoptosis and limit chloride secretion in human intestinal epithelial cells : Implications for inflammatory diarrheal states. / Abreu, Maria T; Arnold, Elizabeth T.; Chow, Jimmy Y C; Barrett, Kim E.

In: Journal of Biological Chemistry, Vol. 276, No. 50, 14.12.2001, p. 47563-47574.

Research output: Contribution to journalArticle

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abstract = "The epithelial lining of the intestine serves as a barrier to lumenal bacteria and can be compromised by pathologic Fas-mediated epithelial apoptosis. Phosphatidylinositol (PI)3-kinase signaling has been described to limit apoptosis in other systems. We hypothesized that PI3-kinase-dependent pathways regulate Fas-mediated apoptosis and barrier function in intestiynal epithelial cells (IEC). IEC lines (HT-29 and T84) were exposed to agonist anti-Fas antibody in the presence or absence of chemical inhibitors of PI3-kinase (LY294002 and wortmannin). Apoptosis, barrier function, changes in short circuit current (ΔIsc), and expression of adhesion molecules were assessed. Inhibition of PI3-kinase strongly sensitized IEC to Fas-mediated apoptosis. Expression of constitutively active Akt, a principal downstream effector of the PI3-kinase pathway, protected against Fas-mediated apoptosis to an extent that was comparable with expression of a genetic caspase inhibitor, p35. PI3-kinase inhibition sensitized to apoptosis by increasing and accelerating Fas-mediated caspase activation. Inhibition of PI3-kinase combined with cross-linking Fas was associated with increased permeability to molecules that were <400 Da but not those that were >3,000 Da. Inhibition of PI3-kinase resulted in chloride secretion that was augmented by cross-linking Fas. Confocal analyses revealed polymerization of actin and maintenance of epithelial cell adhesion molecule-mediated interactions in monolayers exposed to anti-Fas antibody in the context of PI3-kinase inhibition. PI3-kinase-dependent pathways, especially Akt, protect IEC against Fas-mediated apoptosis. Inhibition of PI3-kinase in the context of Fas signaling results in increased chloride secretion and barrier dysfunction. These findings suggest that agonists of PI3-kinase such as growth factors may have a dual effect on intestinal inflammation by protecting epithelial cells against immune-mediated apoptosis and limiting chloride secretory diarrhea.",
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