SWAP70 Organizes the Actin Cytoskeleton and Is Essential for Phagocytosis

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


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism*
  • Actins / metabolism
  • DNA-Binding Proteins / metabolism*
  • Dendritic Cells / metabolism
  • Gene Knockdown Techniques
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Humans
  • Minor Histocompatibility Antigens / metabolism*
  • Nuclear Proteins / metabolism*
  • Phagocytosis*
  • Phagosomes / metabolism
  • Phosphatidylinositol Phosphates / metabolism
  • Polymerization
  • rac1 GTP-Binding Protein / metabolism


  • Actins
  • DNA-Binding Proteins
  • Guanine Nucleotide Exchange Factors
  • Minor Histocompatibility Antigens
  • Nuclear Proteins
  • Phosphatidylinositol Phosphates
  • SWAP70 protein, human
  • phosphatidylinositol 3,4-diphosphate
  • rac1 GTP-Binding Protein