title: Requirements for both Rac1 and Cdc42 in membrane ruffling and phagocytosis in leukocytes.
abstract: Specific pathways linking heterotrimeric G proteins and Fcgamma receptors to the actin-based cytoskeleton are poorly understood. To test a requirement for Rho family members in cytoskeletal events mediated by structurally diverse receptors in leukocytes, we transfected the full-length human chemotactic peptide receptor in RAW 264.7 cells and examined cytoskeletal alterations in response to the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP), colony stimulating factor-1 (CSF-1), IgG-coated particles, and phorbol 12-myristate 13-acetate (PMA). Expression of Rac1 N17, Cdc42 N17, or the GAP domain of n-chimaerin inhibited cytoskeletal responses to FMLP and CSF-1, and blocked phagocytosis. Accumulation of F-actin- rich "phagocytic cups" was partially inhibited by expression of Rac1 N17 or Cdc42 N17. In contrast, PMA-induced ruffling was not inhibited by expression of Rac1 N17, but was blocked by expression of Cdc42 N17, indicating that cytoskeletal inhibition by these constructs was nonoverlapping. These results demonstrate differential requirements for Rho family GTPases in leukocyte motility, and indicate that both Rac1 and Cdc42 are required for Fcgamma receptor- mediated phagocytosis and for membrane ruffling mediated by structurally distinct receptors in macrophages.
authors.affiliation: Pulmonary Division, Department of Medicine, Columbia University College of Physicians and Surgeons, New York 10032, USA.
authors.forename: D
authors.initials: D
authors.lastname: Cox
authors.forename: P
authors.initials: P
authors.lastname: Chang
authors.forename: Q
authors.initials: Q
authors.lastname: Zhang
authors.forename: P G
authors.initials: PG
authors.lastname: Reddy
authors.forename: G M
authors.initials: GM
authors.lastname: Bokoch
authors.forename: S
authors.initials: S
authors.lastname: Greenberg
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects; D020848:Chimerin 1; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology; D020558:GTP Phosphohydrolases / Q000096:biosynthesis / Q000235:genetics; D019204:GTP-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D020690:GTPase-Activating Proteins; D006801:Humans; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D010587:Phagocytosis / Q000187:drug effects; D011506:Proteins / Q000494:pharmacology; D044042:Receptors, Formyl Peptide; D017452:Receptors, IgG / Q000502:physiology; D011971:Receptors, Immunologic / Q000096:biosynthesis; D018000:Receptors, Peptide / Q000096:biosynthesis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D020744:rac GTP-Binding Proteins
chemical_list: D018797:Cell Cycle Proteins; D020848:Chimerin 1; D020690:GTPase-Activating Proteins; D009419:Nerve Tissue Proteins; D011506:Proteins; D044042:Receptors, Formyl Peptide; D017452:Receptors, IgG; D011971:Receptors, Immunologic; D018000:Receptors, Peptide; D009240:N-Formylmethionine Leucyl-Phenylalanine; D016173:Macrophage Colony-Stimulating Factor; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020744:rac GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate