Abstract
Ras proteins control the signalling pathways that are responsible for normal growth and malignant transformation. Raf protein kinases are direct Ras effector proteins that initiate the mitogen-activated protein kinase (MAPK) cascade, which mediates diverse biological functions such as cell growth, survival and differentiation. Here we show that prohibitin, a ubiquitously expressed and evolutionarily conserved protein is indispensable for the activation of the Raf-MEK-ERK pathway by Ras. The membrane targeting and activation of C-Raf by Ras needs prohibitin in vivo. In addition, direct interaction with prohibitin is required for C-Raf activation. C-Raf kinase fails to interact with the active Ras induced by epidermal growth factor in the absence of prohibitin. Moreover, in prohibitin-deficient cells the adhesion complex proteins cadherin and beta-catenin relocalize to the plasma membrane and thereby stabilize adherens junctions. Our data show an unexpected role of prohibitin in the activation of the Ras-Raf signalling pathway and in modulating epithelial cell adhesion and migration.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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14-3-3 Proteins / metabolism
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Cadherins / metabolism
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Caveolae / metabolism
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Cell Adhesion / drug effects
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Cell Adhesion / genetics
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Cell Line, Tumor
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Cell Movement / genetics
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Cell Movement / physiology*
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Cell Shape / drug effects
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Cell Shape / genetics
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Cytoskeletal Proteins / metabolism
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Cytosol / metabolism
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Enzyme Inhibitors / pharmacology
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Epidermal Growth Factor / pharmacology
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Epithelial Cells / drug effects
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Epithelial Cells / physiology*
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Epithelial Cells / ultrastructure
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Flavonoids / pharmacology
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HeLa Cells
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Humans
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MAP Kinase Signaling System / physiology*
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Microscopy, Electron, Scanning
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Microscopy, Electron, Transmission
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Mitogen-Activated Protein Kinase 1 / metabolism
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Mitogen-Activated Protein Kinase 3 / metabolism
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Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinase Kinases / metabolism
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Phosphorylation / drug effects
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Prohibitins
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Protein Binding
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Protein Serine-Threonine Kinases / metabolism
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins c-akt
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Proto-Oncogene Proteins c-raf / genetics
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Proto-Oncogene Proteins c-raf / metabolism
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RNA, Small Interfering / genetics
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Repressor Proteins / genetics
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Repressor Proteins / metabolism
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Repressor Proteins / physiology*
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Tetradecanoylphorbol Acetate / pharmacology
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Trans-Activators / metabolism
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Transfection
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beta Catenin
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raf Kinases / genetics
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raf Kinases / metabolism*
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ras Proteins / metabolism
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ras Proteins / physiology*
Substances
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14-3-3 Proteins
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CTNNB1 protein, human
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Cadherins
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Cytoskeletal Proteins
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Enzyme Inhibitors
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Flavonoids
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Prohibitins
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Proto-Oncogene Proteins
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RNA, Small Interfering
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Repressor Proteins
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Trans-Activators
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beta Catenin
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Epidermal Growth Factor
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Protein Serine-Threonine Kinases
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Proto-Oncogene Proteins c-akt
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Proto-Oncogene Proteins c-raf
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raf Kinases
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinase Kinases
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ras Proteins
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Tetradecanoylphorbol Acetate
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2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one