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.
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.
Yuya
Y
Terashima
Nobuyuki
N
Onai
Masako
M
Murai
Masahiko
M
Enomoto
Vongsakorn
V
Poonpiriya
Tsuyoshi
T
Hamada
Kazushi
K
Motomura
Makiko
M
Suwa
Taichi
T
Ezaki
Tatsuya
T
Haga
Shiro
S
Kanegasaki
Kouji
K
Matsushima
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