title: Rab35 regulates phagosome formation through recruitment of ACAP2 in macrophages during FcγR-mediated phagocytosis.
abstract: Phagosome formation and subsequent maturation are complex sequences of events that involve actin cytoskeleton remodeling and membrane trafficking. Here, we demonstrate that the Ras-related protein Rab35 is involved in the early stage of FcγR-mediated phagocytosis in macrophages. Live-cell image analysis revealed that Rab35 was markedly concentrated at the membrane where IgG-opsonized erythrocytes (IgG-Es) are bound. Rab35 silencing by RNA interference (RNAi) or the expression of GDP- or GTP-locked Rab35 mutant drastically reduced the rate of phagocytosis of IgG-Es. Actin-mediated pseudopod extension to form phagocytic cups was disturbed by the Rab35 silencing or the expression of GDP-Rab35, although initial actin assembly at the IgG-E binding sites was not inhibited. Furthermore, GTP-Rab35-dependent recruitment of ACAP2, an ARF6 GTPase-activating protein, was shown in the phagocytic cup formation. Concomitantly, overexpression of ACAP2 along with GTP-locked Rab35 showed a synergistic inhibitory effect on phagocytosis. It is likely that Rab35 regulates actin-dependent phagosome formation by recruiting ACAP2, which might control actin remodeling and membrane traffic through ARF6.
authors: Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Kagawa 761-0793,  Japan.
authors: Youhei
authors: Y
authors: Egami
authors: Mitsunori
authors: M
authors: Fukuda
authors: Nobukazu
authors: N
authors: Araki
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D010587:Phagocytosis; D010588:Phagosomes / Q000235:genetics / Q000276:immunology*; D017452:Receptors, IgG / Q000235:genetics / Q000276:immunology*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000276:immunology*
chemical_list: C570848:ACAP2 protein, mouse; D020690:GTPase-Activating Proteins; D017452:Receptors, IgG; C543587:Rab35 protein, mouse; D020691:rab GTP-Binding Proteins