Requirements for Vav guanine nucleotide exchange factors and Rho GTPases in FcgammaR- and complement-mediated phagocytosis.
Vav guanine nucleotide exchange factors (GEFs) have been implicated in cell adhesion by integrin and immune response receptors through the regulation of Rho GTPases. Here, we examine the role of Vav and Rho GTPases in phagocytosis by using primary murine macrophages. The genetic deletion of Rac1 and Rac2 prevents phagocytosis mediated by integrin and Fcgamma receptors (FcgammaR), whereas the genetic deletion of Vav1 and Vav3 only prevents integrin-mediated phagocytosis through the complement receptor alpha(M)beta(2). In addition, a Rac1/2 or Vav1/3 deficiency blocks Arp2/3 recruitment and actin polymerization at the complement-induced phagosome, indicating that these proteins regulate early steps in phagocytosis. Moreover, constitutively active Rac is able to rescue actin polymerization and complement-mediated phagocytosis in Vav-deficient macrophages. These studies indicate that Rac is critical for complement- and FcgammaR-mediated phagocytosis. In contrast, Vav is specifically required for complement-mediated phagocytosis, suggesting that Rac is regulated by GEFs other than Vav downstream of the FcgammaR.
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Amy B
AB
Hall
M Angelica Martinez
MA
Gakidis
Michael
M
Glogauer
Julie L
JL
Wilsbacher
Sizhen
S
Gao
Wojciech
W
Swat
Joan S
JS
Brugge
D000199:Actins / Q000378:metabolism; D000818:Animals; D020662:Guanine Nucleotide Exchange Factors / Q000502:physiology*; D016177:Macrophage-1 Antigen / Q000502:physiology*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D010587:Phagocytosis; D051567:Proto-Oncogene Proteins c-vav / Q000502:physiology*; D017452:Receptors, IgG / Q000502:physiology*; D015398:Signal Transduction; D020744:rac GTP-Binding Proteins / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000502:physiology; D020741:rho GTP-Binding Proteins / Q000502:physiology*; D000097766:RAC2 GTP-Binding Protein
D000199:Actins; D020662:Guanine Nucleotide Exchange Factors; D016177:Macrophage-1 Antigen; D051567:Proto-Oncogene Proteins c-vav; D017452:Receptors, IgG; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D000097766:RAC2 GTP-Binding Protein; C496619:Vav1 protein, mouse; C496622:Vav3 protein, mouse