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Cell Rep. 2016 Nov 1;17(6):1518-1531. doi: 10.1016/j.celrep.2016.10.021.

SWAP70 Organizes the Actin Cytoskeleton and Is Essential for Phagocytosis.

Author information

1
Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands.
2
Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
3
Department of Tumor Immunology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Geert Grooteplein 28, 6525GA Nijmegen, the Netherlands. Electronic address: geert.vandenbogaart@radboudUMC.nl.

Abstract

Actin plays a critical role during the early stages of pathogenic microbe internalization by immune cells. In this study, we identified a key mechanism of actin filament tethering and stabilization to the surface of phagosomes in human dendritic cells. We found that the actin-binding protein SWAP70 is specifically recruited to nascent phagosomes by binding to the lipid phosphatidylinositol (3,4)-bisphosphate. Multi-color super-resolution stimulated emission depletion (STED) microscopy revealed that the actin cage surrounding early phagosomes is formed by multiple concentric rings containing SWAP70. SWAP70 colocalized with and stimulated activation of RAC1, a known activator of actin polymerization, on phagosomes. Genetic ablation of SWAP70 impaired actin polymerization around phagosomes and resulted in a phagocytic defect. These data show a key role for SWAP70 as a scaffold for tethering the peripheral actin cage to phagosomes.

KEYWORDS:

Rac1; STED microscopy; SWAP70; actin; cytoskeleton; dendritic cell; phagocytosis; phosphatidylionositol 3,4-bisphosphate; phosphoinositides; rho-GTPases

PMID:
27806292
PMCID:
PMC5149533
DOI:
10.1016/j.celrep.2016.10.021
[Indexed for MEDLINE]
Free PMC Article

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