Abstract
Front-rear asymmetry in motile cells is crucial for efficient directional movement. The uropod in migrating lymphocytes is a posterior protrusion in which several proteins, including CD44 and ezrin/radixin/moesin (ERM), are concentrated. In EL4.G8 T-lymphoma cells, Thr567 phosphorylation in the COOH-terminal domain of ezrin regulates the selective localization of ezrin in the uropod. Overexpression of the phosphorylation-mimetic T567D ezrin enhances uropod size and cell migration. T567D ezrin also induces construction of the CD44-associated polar cap, which covers the posterior cytoplasm in staurosporine-treated, uropod-disrupted EL4.G8 cells or in naturally unpolarized X63.653 myeloma cells in an actin cytoskeleton-dependent manner. Rho-associated coiled coil-containing protein kinase (ROCK) inhibitor Y-27632 disrupts the uropod but not the polar cap, indicating that Rho-ROCK signaling is required for posterior protrusion but not for ERM phosphorylation. Phosphorylated ezrin associates with Dbl through its NH2-terminal domain and causes Rho activation. Moreover, constitutively active Q63L RhoA is selectively localized in the rear part of the cells. Thus, phosphorylated ERM has a potential function in establishing plasma membrane "posteriority" in the induction of the uropod in T lymphocytes.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Actins / metabolism
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Amides / pharmacology
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Animals
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Blood Proteins / metabolism*
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Blotting, Western
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Cell Line, Tumor
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Cell Membrane / metabolism
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Cell Movement
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Cell Nucleus / metabolism
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Chemotaxis
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Cytoplasm / metabolism
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Cytoskeletal Proteins / metabolism*
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Cytoskeleton / metabolism
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Enzyme Activation
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Enzyme Inhibitors / pharmacology
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Green Fluorescent Proteins / metabolism
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Guanine Nucleotide Exchange Factors / metabolism
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Hyaluronan Receptors / biosynthesis
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Hyaluronan Receptors / metabolism
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Immunoprecipitation
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Intracellular Signaling Peptides and Proteins
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Lymphocytes / metabolism*
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Lymphoma, T-Cell / metabolism
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Membrane Proteins / metabolism*
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Mice
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Microfilament Proteins / metabolism*
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Microscopy, Fluorescence
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Models, Biological
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Phosphoproteins / metabolism*
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Phosphorylation
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Plasmids / metabolism
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Protein Serine-Threonine Kinases / metabolism*
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Protein Structure, Tertiary
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Pyridines / pharmacology
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Signal Transduction
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Time Factors
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Transfection
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rho-Associated Kinases
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rhoA GTP-Binding Protein / metabolism
Substances
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Actins
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Amides
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Blood Proteins
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Cytoskeletal Proteins
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Enzyme Inhibitors
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Guanine Nucleotide Exchange Factors
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Hyaluronan Receptors
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Intracellular Signaling Peptides and Proteins
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Membrane Proteins
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Microfilament Proteins
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Phosphoproteins
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Pyridines
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ezrin
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Y 27632
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moesin
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radixin
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Green Fluorescent Proteins
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Protein Serine-Threonine Kinases
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rho-Associated Kinases
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rhoA GTP-Binding Protein