Pivotal function for cytoplasmic protein FROUNT in CCR2-mediated monocyte chemotaxis.
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.
Terashima
Yuya
Y
Department of Molecular Preventive Medicine (and Solution Oriented Research for Science and Technology), Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Onai
Nobuyuki
N
Murai
Masako
M
Enomoto
Masahiko
M
Poonpiriya
Vongsakorn
V
Hamada
Tsuyoshi
T
Motomura
Kazushi
K
Suwa
Makiko
M
Ezaki
Taichi
T
Haga
Tatsuya
T
Kanegasaki
Shiro
S
Matsushima
Kouji
K
D000595:Amino Acid Sequence; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002633:Chemotaxis; D033922:Clathrin Heavy Chains / Q000096:biosynthesis* / Q000502:physiology*; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism*; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation; D008024:Ligands; D008264:Macrophages / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009000:Monocytes / Q000166:cytology*; D009154:Mutation; D028861:Nuclear Pore Complex Proteins; D010455:Peptides / Q000737:chemistry; D010538:Peritonitis / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D021381:Protein Transport; D011554:Pseudopodia / Q000378:metabolism; D054390:Receptors, CCR2; D019707:Receptors, Chemokine / Q000737:chemistry*; D012190:Retroviridae / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D013997:Time Factors
C515334:CCR2 protein, human; C515335:Ccr2 protein, mouse; D018076:DNA, Complementary; C503215:FROUNT protein, mouse; D008024:Ligands; C503214:NUP85 protein, human; D028861:Nuclear Pore Complex Proteins; D010455:Peptides; D054390:Receptors, CCR2; D019707:Receptors, Chemokine; D033922:Clathrin Heavy Chains; D005982:Glutathione Transferase; D019869:Phosphatidylinositol 3-Kinases