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

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

Author information

1
National Centre for Biological Science (TIFR), Bellary Road, Bangalore, 560065, India.
2
Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD, 4072, Australia.
3
Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, QLD, 4072, Australia.
4
IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, 20139, Italy.
5
Department of Oncology and Hemato-Oncology, University of Milan, Milan, 20122, Italy.
6
Simons Centre for the Study of Living Machines, National Centre for Biological Sciences (TIFR), Bellary Road, Bangalore, 560065, India.
7
National Centre for Biological Science (TIFR), Bellary Road, Bangalore, 560065, India. mayor@ncbs.res.in.
8
Institute for Stem Cell Biology and Regenerative Medicine, Bellary Road, Bangalore, 560065, India. mayor@ncbs.res.in.

Abstract

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.

PMID:
29743604
PMCID:
PMC5943408
DOI:
10.1038/s41467-018-03955-w
[Indexed for MEDLINE]
Free PMC Article

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