Activation of both MAP kinase and phosphatidylinositide 3-kinase by Ras is required for hepatocyte growth factor/scatter factor-induced adherens junction disassembly

• Published in: Molecular biology of the cell 1998-08, Vol.9 (8), p.2185-2200
• Main Authors: Potempa, S, Ridley, A J
• Format: Article
• Language: English
• Subjects: Animals; beta Catenin; Cadherins - physiology; Calcium-Calmodulin-Dependent Protein Kinases - antagonists & inhibitors; Calcium-Calmodulin-Dependent Protein Kinases - metabolism; Cell Adhesion - drug effects; Cell Adhesion - physiology; Cell Line; Chromones - pharmacology; Cytoskeletal Proteins - physiology; Desmosomes - drug effects; Desmosomes - physiology; Dogs; Enzyme Activation; Enzyme Inhibitors - pharmacology; Epithelial Cells - cytology; Epithelial Cells - drug effects; Epithelial Cells - physiology; Flavonoids - pharmacology; GTP-Binding Proteins - physiology; Hepatocyte Growth Factor - pharmacology; Hepatocyte Growth Factor - physiology; Intercellular Junctions - drug effects; Intercellular Junctions - physiology; Kidney; Morpholines - pharmacology; Phosphatidylinositol 3-Kinases - antagonists & inhibitors; Phosphatidylinositol 3-Kinases - metabolism; rac GTP-Binding Proteins; ras Proteins - physiology; Signal Transduction; Trans-Activators; Transfection
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.9.8.2185

Hepatocyte growth factor/scatter factor (HGF/SF) stimulates the motility of epithelial cells, initially inducing centrifugal spreading of colonies followed by disruption of cell-cell junctions and subsequent cell scattering. In Madin-Darby canine kidney cells, HGF/SF-induced motility involves actin reorganization mediated by Ras, but whether Ras and downstream signals regulate the breakdown of intercellular adhesions has not been established. Both HGF/SF and V12Ras induced the loss of the adherens junction proteins E-cadherin and beta-catenin from intercellular junctions during cell spreading, and the HGF/SF response was blocked by dominant-negative N17Ras. Desmosomes and tight junctions were regulated separately from adherens junctions, because they were not disrupted by V12Ras. MAP kinase, phosphatidylinositide 3-kinase (PI 3-kinase), and Rac were required downstream of Ras, because loss of adherens junctions was blocked by the inhibitors PD098059 and LY294002 or by dominant-inhibitory mutants of MAP kinase kinase 1 or Rac1. All of these inhibitors also prevented HGF/SF-induced cell scattering. Interestingly, activated Raf or the activated p110alpha subunit of PI 3-kinase alone did not induce disruption of adherens junctions. These results indicate that activation of both MAP kinase and PI 3-kinase by Ras is required for adherens junction disassembly and that this is essential for the motile response to HGF/SF.