Fak/Src signaling in human intestinal epithelial cell survival and anoikis: differentiation state-specific uncoupling with the PI3-K/Akt-1 and MEK/Erk pathways.
Human intestinal epithelial cell survival and anoikis are distinctively regulated according to the state of differentiation. In the present study, we analyzed the roles of focal adhesion kinase (Fak)/Src signaling to the PI3-K/Akt-1 and mitogen-activated protein kinase (MEK)/extracellular regulated kinases (Erk) pathways, within the context of such differentiation-state distinctions. Anoikis was induced by inhibition of beta1 integrins (antibody blocking), inhibition of Fak (pharmacologic inhibition or overexpression of dominant negative mutants), or by maintaining cells in suspension. Activation parameters of Fak, Src, Akt-1, and Erk1/2 were analyzed. Activities of Src, Akt-1, or Erk1/2 were also blocked by pharmacological inhibition or by overexpression of dominant-negative mutants. We report that: (1) the loss or inhibition of beta1 integrin binding activity causes anoikis and results in a down-activation of Fak, Src, Akt-1, and Erk1/2 in both undifferentiated, and differentiated cells; (2) the inhibition of Fak likewise causes anoikis and a down-activation of Src, Akt-1, and Erk1/2, regardless of the differentiation state; (3) Src, PI3-K/Akt-1, and MEK/Erk contribute to the survival of differentiated cells, whereas MEK/Erk does not play a role in the survival of undifferentiated ones; (4) the inhibition/loss of beta1 integrin binding and/or Fak activity results in a loss of Src engagement with Fak, regardless of the state of differentiation; and (5) Src contributes to the activation of both the PI3-K/Akt-1 and MEK/Erk pathways in undifferentiated cells, but does not influence PI3-K/Akt-1 in differentiated ones. Hence, Fak/Src signaling to the PI3-K/Akt-1 and MEK/Erk pathways undergoes a differentiation state-specific uncoupling which ultimately reflects upon the selective engagement of these same pathways in the mediation of intestinal epithelial cell survival.
Bouchard
Véronique
V
Département d'Anatomie et de Biologie Cellulaire, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Québec, Canada.
Demers
Marie-Josée
MJ
Thibodeau
Sonya
S
Laquerre
Vincent
V
Fujita
Naoya
N
Tsuruo
Takashi
T
Beaulieu
Jean-François
JF
Gauthier
Rémy
R
Vézina
Anne
A
Villeneuve
Lisabeth
L
Vachon
Pierre H
PH
D023102:Anoikis; D018938:Caco-2 Cells; D002448:Cell Adhesion; D002454:Cell Differentiation; D002470:Cell Survival; D020895:Enterocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection
D048049:Extracellular Signal-Regulated MAP Kinases; D051417:Focal Adhesion Kinase 1; D019012:Integrin beta1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D016392:Proto-Oncogene Proteins pp60(c-src); C496050:PTK2 protein, human