Small GTPases and BAR domain proteins regulate branched actin polymerisation for clathrin and dynamin-independent endocytosis

Nat Commun. 2018 May 9;9(1):1835. doi: 10.1038/s41467-018-03955-w.


Using real-time TIRF microscopy imaging, we identify sites of clathrin and dynamin-independent CLIC/GEEC (CG) endocytic vesicle formation. This allows spatio-temporal localisation of known molecules affecting CG endocytosis; GBF1 (a GEF for ARF1), ARF1 and CDC42 which appear sequentially over 60 s, preceding scission. In an RNAi screen for BAR domain proteins affecting CG endocytosis, IRSp53 and PICK1, known interactors of CDC42 and ARF1, respectively, were selected. Removal of IRSp53, a negative curvature sensing protein, abolishes CG endocytosis. Furthermore, the identification of ARP2/3 complex at CG endocytic sites, maintained in an inactive state reveals a function for PICK1, an ARP2/3 inhibitor. The spatio-temporal sequence of the arrival and disappearance of the molecules suggest a mechanism for a clathrin and dynamin-independent endocytic process. Coincident with the loss of PICK1 by GBF1-activated ARF1, CDC42 recruitment leads to the activation of IRSp53 and the ARP2/3 complex, resulting in a burst of F-actin polymerisation potentially powering scission.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-Ribosylation Factor 1 / genetics
  • ADP-Ribosylation Factor 1 / metabolism*
  • Actins / chemistry*
  • Actins / metabolism
  • Animals
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Clathrin / chemistry
  • Clathrin / metabolism*
  • Dynamins / chemistry
  • Dynamins / metabolism*
  • Endocytosis*
  • Fibroblasts / enzymology
  • Fibroblasts / metabolism
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / metabolism
  • Humans
  • Mice
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Polymerization
  • Protein Binding
  • Protein Domains
  • cdc42 GTP-Binding Protein / genetics
  • cdc42 GTP-Binding Protein / metabolism*


  • Actins
  • BAIAP2 protein, human
  • Carrier Proteins
  • Clathrin
  • GBF1 protein, human
  • Guanine Nucleotide Exchange Factors
  • Nerve Tissue Proteins
  • Nuclear Proteins
  • PICk1 protein, human
  • ADP-Ribosylation Factor 1
  • cdc42 GTP-Binding Protein
  • Dynamins