title: Phosphatidylinositol 3-kinase controls human intestinal epithelial cell differentiation by promoting adherens junction assembly and p38 MAPK activation.
abstract: The signaling pathways mediating human intestinal epithelial cell differentiation remain largely undefined. Phosphatidylinositol 3-kinase (PI3K) is an important modulator of extracellular signals, including those elicited by E-cadherin-mediated cell-cell adhesion, which plays an important role in maintenance of the structural and functional integrity of epithelia. In this study, we analyzed the involvement of PI3K in the differentiation of human intestinal epithelial cells. We showed that inhibition of PI3K signaling in Caco-2/15 cells repressed sucrase-isomaltase and villin protein expression. Morphological differentiation of enterocyte-like features in Caco-2/15 cells such as epithelial cell polarity and brush-border formation were strongly attenuated by PI3K inhibition. Immunofluorescence and immunoprecipitation experiments revealed that PI3K was recruited to and activated by E-cadherin-mediated cell-cell contacts in confluent Caco-2/15 cells, and this activation appears to be essential for the integrity of adherens junctions and association with the cytoskeleton. We provide evidence that the assembly of calcium-dependent adherens junctions led to a rapid and remarkable increase in the state of activation of Akt and p38 MAPK pathways and that this increase was blocked in the presence of anti-E-cadherin antibodies and PI3K inhibitor. Therefore, our results indicate that PI3K promotes assembly of adherens junctions, which, in turn, control p38 MAPK activation and enterocyte differentiation.
authors.affiliation: Canadian Institutes of Health Research Group on Functional Development and Physiopathology of the Digestive Tract, Département d'Anatomie et Biologie Cellulaire, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: Laprise
authors.forename: Pierre
authors.initials: P
authors.lastname: Chailler
authors.forename: Mathieu
authors.initials: M
authors.lastname: Houde
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Beaulieu
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Boucher
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rivard
mesh_terms: D022005:Adherens Junctions / Q000737:chemistry*; D018938:Caco-2 Cells; D015820:Cadherins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002454:Cell Differentiation; D002460:Cell Line; D002465:Cell Movement; D003599:Cytoskeleton / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology* / Q000201:enzymology* / Q000378:metabolism; D017930:Genes, Reporter; D005822:Genetic Vectors; D006801:Humans; D015151:Immunoblotting; D007422:Intestines / Q000166:cytology; D008156:Luciferases / Q000378:metabolism; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D048308:Mitogen-Activated Protein Kinase 14; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D019869:Phosphatidylinositol 3-Kinases / Q000737:chemistry* / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013997:Time Factors; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D015820:Cadherins; D002118:Calcium; D008156:Luciferases; D048308:Mitogen-Activated Protein Kinase 14; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D048051:p38 Mitogen-Activated Protein Kinases