Activation of both MAP kinase and phosphatidylinositide 3-kinase by Ras is required for hepatocyte growth factor/scatter factor-induced adherens junction disassembly.
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.
Ludwig Institute for Cancer Research, University College London Branch, London W1P 8BT, United Kingdom.
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Potempa
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Ridley
D000818:Animals; D015820:Cadherins / Q000502:physiology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000502:physiology; D003896:Desmosomes / Q000187:drug effects / Q000502:physiology; D004285:Dogs; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D005419:Flavonoids / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D017228:Hepatocyte Growth Factor / Q000494:pharmacology* / Q000502:physiology; D007365:Intercellular Junctions / Q000187:drug effects / Q000502:physiology*; D007668:Kidney; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D015398:Signal Transduction; D015534:Trans-Activators; D014162:Transfection; D051176:beta Catenin; D020744:rac GTP-Binding Proteins; D018631:ras Proteins / Q000502:physiology*
D015820:Cadherins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002867:Chromones; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D019204:GTP-Binding Proteins; D017228:Hepatocyte Growth Factor; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D015534:Trans-Activators; D051176:beta Catenin; D020744:rac GTP-Binding Proteins; D018631:ras Proteins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one