title: Dynamin is required for the activation of mitogen-activated protein (MAP) kinase by MAP kinase kinase.
abstract: Internalization of activated receptors from the plasma membrane has been implicated in the activation of mitogen-activated protein (MAP) kinase. However, the mechanism whereby membrane trafficking may regulate mitogenic signaling remains unclear. Here we report that dominant-negative dynamin (K44A), an inhibitor of endocytic vesicle formation, abrogates MAP kinase activation in response to epidermal growth factor, lysophosphatidic acid, and protein kinase C-activating phorbol ester. In contrast, dynamin-K44A does not affect the activation of Ras, Raf, and MAP kinase kinase (MEK) by either agonist. Through immunofluorescence and subcellular fractionation studies, we find that activated MEK is present both at the plasma membrane and in intracellular vesicles but not in the cytosol. Our findings suggest that dynamin-regulated endocytosis of activated MEK, rather than activated receptors, is a critical event in the MAP kinase activation cascade.
authors.affiliation: Division of Cellular Biochemistry, The Netherlands Cancer Institute and Centre for Biomedical Genetics, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands.
authors.forename: O
authors.initials: O
authors.lastname: Kranenburg
authors.forename: I
authors.initials: I
authors.lastname: Verlaan
authors.forename: W H
authors.initials: WH
authors.lastname: Moolenaar
mesh_terms: D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism; D034281:Dynamins; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D020558:GTP Phosphohydrolases; D018631:ras Proteins; D034281:Dynamins