PAG3/Papalpha/KIAA0400, a GTPase-activating protein for ADP-ribosylation factor (ARF), regulates ARF6 in Fcgamma receptor-mediated phagocytosis of macrophages.
The Fcgamma receptor (FcgammaR)-mediated phagocytosis of macrophages is a complex process where remodeling of both the actin-based cytoskeleton and plasma membrane occur coordinately. Several different families of small GTPases are involved. We have isolated a GTPase-activating protein (GAP) for ADP-ribosylation factor (ARF), paxillin-associated protein with ARFGAP activity (PAG)3/Papalpha/KIAA0400, from mature monocytes and macrophage-like cells. Mammalian ARFs fall into three classes, and the class III isoform (ARF6) has been shown to be involved in FcgammaR-mediated phagocytosis. Here we report that PAG3 is enriched together with ARF6 and F-actin at phagocytic cups formed beneath immunoglobulin G-opsonized beads in P388D1 macrophages, in which overexpression of ARF6, but not ARF1 (class I) or ARF5 (class II), inhibits the phagocytosis. Overexpression of PAG3, but not its GAP-inactive mutant, attenuated the focal accumulation of F-actin and blocked phagocytosis, although surface levels of the FcgammaRs were not affected. Other ubiquitously expressed ARFGAPs, G protein-coupled receptor kinase interactors GIT2 and GIT2-short/KIAA0148, which we have shown to exhibit GAP activity for ARF1 in COS-7 cells, did not accumulate at the phagocytic cups or inhibit phagocytosis. Moreover, cooverexpression of ARF6, but not ARF1 or ARF5, restored the phagocytic activity of PAG3-overexpressing cells. We propose that PAG3 acts as a GAP for ARF6 and is hence involved in FcgammaR-mediated phagocytosis in mouse macrophages.
Uchida
H
H
Department of Molecular Biology, Osaka Bioscience Institute, Osaka 565-0874, Japan.
Kondo
A
A
Yoshimura
Y
Y
Mazaki
Y
Y
Sabe
H
H
D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D019204:GTP-Binding Proteins / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008264:Macrophages / Q000276:immunology / Q000502:physiology*; D051379:Mice; D010587:Phagocytosis / Q000502:physiology*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017452:Receptors, IgG / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D016335:Zinc Fingers
D000089982:ADP-Ribosylation Factor 6; C503237:ARFGAP1 protein, human; C503240:ARFGAP3 protein, human; D000199:Actins; C503238:Arfgap1 protein, mouse; C503241:Arfgap3 protein, mouse; D020690:GTPase-Activating Proteins; D020033:Protein Isoforms; D017452:Receptors, IgG; D011994:Recombinant Proteins; C410332:ASAP2 protein, human; D019204:GTP-Binding Proteins; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human; C486477:Arf5 protein, mouse; C000715727:Arf6 protein, mouse