Enterocytic differentiation of the human Caco-2 cell line correlates with alterations in integrin signaling.
We previously reported that the enterocytic differentiation of human colonic Caco-2 cells correlated with down-regulation of fibronectin (FN) and laminin (LN), two extracellular matrix components interacting with cell surface integrin receptors. We now investigated whether Caco-2 cell differentiation was associated with alterations in integrin signaling with special interest in the expression and activity of focal adhesion kinase (FAK) and mitogen-activated protein (MAP) kinase. The differentiation of Caco-2 cells was associated with: 1) down-regulation of beta1 integrin expression at the mRNA and protein levels; 2) increased FAK expression together with decreased FAK autophosphorylation; 3) decreased FAK's ability to associate with PI3-kinase and pp60c-src; and 4) increased MAP kinase expression along with decreased MAP activity. In addition, we show that FAK and MAP kinase belong to distinct integrin signaling pathways and that both pathways remain functional during Caco-2 cell differentiation since the coating of differentiating cells on FN and LN but not on polylysine increased the tyrosine phosphorylation of FAK and of its endogenous substrate paxillin, and stimulated MAP kinase activity. In conclusion, our results provide evidence that FAK and MAP kinase, two signaling molecules activated independently by beta1 integrins in Caco-2 cells, undergo alterations of both expression and activity during the enterocytic differentiation of this cell line.
Lévy
P
P
INSERM-U.402, Faculté de Médecine Saint-Antoine, Paris, France. peggy.levy@adr.st-antoine.inserm.fr
Robin
H
H
Kornprobst
M
M
Capeau
J
J
Cherqui
G
G
D018938:Caco-2 Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000096:biosynthesis / Q000502:physiology*; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000502:physiology*; D002454:Cell Differentiation; D003106:Colon / Q000166:cytology*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004789:Enzyme Activation; D004790:Enzyme Induction; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D019012:Integrin beta1 / Q000096:biosynthesis / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000096:biosynthesis / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000502:physiology*; D051419:Paxillin; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D019012:Integrin beta1; D009363:Neoplasm Proteins; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D016392:Proto-Oncogene Proteins pp60(c-src); D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases