Ezrin is a downstream effector of trafficking PKC-integrin complexes involved in the control of cell motility.
Protein kinase C (PKC) alpha has been implicated in beta1 integrin-mediated cell migration. Stable expression of PKCalpha is shown here to enhance wound closure. This PKC-driven migratory response directly correlates with increased C-terminal threonine phosphorylation of ezrin/moesin/radixin (ERM) at the wound edge. Both the wound migratory response and ERM phosphorylation ... are dependent upon the catalytic function of PKC and are susceptible to inhibition by phosphatidylinositol 3-kinase blockade. Upon phorbol 12,13-dibutyrate stimulation, green fluorescent protein-PKCalpha and beta1 integrins co-sediment with ERM proteins in low-density sucrose gradient fractions that are enriched in transferrin receptors. Using fluorescence lifetime imaging microscopy, PKCalpha is shown to form a molecular complex with ezrin, and the PKC-co-precipitated endogenous ERM is hyperphosphorylated at the C-terminal threonine residue, i.e. activated. Electron microscopy showed an enrichment of both proteins in plasma membrane protrusions. Finally, overexpression of the C-terminal threonine phosphorylation site mutant of ezrin has a dominant inhibitory effect on PKCalpha-induced cell migration. We provide the first evidence that PKCalpha or a PKCalpha-associated serine/threonine kinase can phosphorylate the ERM C-terminal threonine residue within a kinase-ezrin molecular complex in vivo.
Mesh Terms:
1-Phosphatidylinositol 3-Kinase, Amino Acid Substitution, Antigens, CD29, Breast Neoplasms, Cell Membrane, Cell Movement, Chromones, Cytoskeletal Proteins, Enzyme Inhibitors, Female, Green Fluorescent Proteins, Humans, Isoenzymes, Kinetics, Luminescent Proteins, Microscopy, Confocal, Morpholines, Mutagenesis, Site-Directed, Phorbol 12,13-Dibutyrate, Phosphoproteins, Phosphorylation, Phosphothreonine, Protein Kinase C, Protein Kinase C-alpha, Recombinant Fusion Proteins, Tumor Cells, Cultured, Wound Healing
1-Phosphatidylinositol 3-Kinase, Amino Acid Substitution, Antigens, CD29, Breast Neoplasms, Cell Membrane, Cell Movement, Chromones, Cytoskeletal Proteins, Enzyme Inhibitors, Female, Green Fluorescent Proteins, Humans, Isoenzymes, Kinetics, Luminescent Proteins, Microscopy, Confocal, Morpholines, Mutagenesis, Site-Directed, Phorbol 12,13-Dibutyrate, Phosphoproteins, Phosphorylation, Phosphothreonine, Protein Kinase C, Protein Kinase C-alpha, Recombinant Fusion Proteins, Tumor Cells, Cultured, Wound Healing
EMBO J.
Date: Jun. 01, 2001
PubMed ID: 11387207
View in: Pubmed Google Scholar
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