Abstract
Ligation of the chemokine receptor CCR2 on monocytes and macrophages with its ligand CCL2 results in activation of the cascade consisting of phosphatidylinositol-3-OH kinase (PI(3)K), the small G protein Rac and lamellipodium protrusion. We show here that a unique clathrin heavy-chain repeat homology protein, FROUNT, directly bound activated CCR2 and formed clusters at the cell front during chemotaxis. Overexpression of FROUNT amplified the chemokine-elicited PI(3)K-Rac-lamellipodium protrusion cascade and subsequent chemotaxis. Blocking FROUNT function by using a truncated mutant or antisense strategy substantially diminished signaling via CCR2. In a mouse peritonitis model, suppression of endogenous FROUNT markedly prevented macrophage infiltration. Thus, FROUNT links activated CCR2 to the PI(3)K-Rac-lamellipodium protrusion cascade and could be a therapeutic target in chronic inflammatory immune diseases associated with macrophage infiltration.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Bone Marrow Cells / cytology
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Cell Line
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Cell Membrane / metabolism
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Chemotaxis
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Clathrin Heavy Chains / biosynthesis*
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Clathrin Heavy Chains / physiology*
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Cloning, Molecular
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Cytoplasm / metabolism*
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DNA, Complementary / metabolism
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Dose-Response Relationship, Drug
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Glutathione Transferase / metabolism
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Humans
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Immunohistochemistry
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Inflammation
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Ligands
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Macrophages / cytology
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Macrophages / immunology
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Macrophages / metabolism
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Mice
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Mice, Inbred C57BL
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Microscopy, Fluorescence
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Molecular Sequence Data
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Monocytes / cytology*
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Mutation
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Nuclear Pore Complex Proteins
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Peptides / chemistry
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Peritonitis / metabolism
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Phosphatidylinositol 3-Kinases / metabolism
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Protein Transport
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Pseudopodia / metabolism
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Receptors, CCR2
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Receptors, Chemokine / chemistry*
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Retroviridae / genetics
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Sequence Analysis, DNA
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Sequence Homology, Amino Acid
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Signal Transduction
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Subcellular Fractions / metabolism
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Time Factors
Substances
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CCR2 protein, human
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Ccr2 protein, mouse
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DNA, Complementary
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FROUNT protein, mouse
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Ligands
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NUP85 protein, human
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Nuclear Pore Complex Proteins
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Peptides
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Receptors, CCR2
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Receptors, Chemokine
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Clathrin Heavy Chains
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Glutathione Transferase
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Phosphatidylinositol 3-Kinases
Associated data
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GENBANK/AF498261
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GENBANK/AF498263