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Filopodial protrusion driven by density-dependent Ena-TOCA-1 interactions.

Published version
Peer-reviewed

Repository DOI


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Authors

Ravishankar, Roshan 

Abstract

Filopodia are narrow actin-rich protrusions with important roles in neuronal development where membrane-binding adaptor proteins, such as I-BAR- and F-BAR-domain-containing proteins, have emerged as upstream regulators that link membrane interactions to actin regulators such as formins and proteins of the Ena/VASP family. Both the adaptors and their binding partners are part of diverse and redundant protein networks that can functionally compensate for each other. To explore the significance of the F-BAR domain-containing neuronal membrane adaptor TOCA-1 (also known as FNBP1L) in filopodia we performed a quantitative analysis of TOCA-1 and filopodial dynamics in Xenopus retinal ganglion cells, where Ena/VASP proteins have a native role in filopodial extension. Increasing the density of TOCA-1 enhances Ena/VASP protein binding in vitro, and an accumulation of TOCA-1, as well as its coincidence with Ena, correlates with filopodial protrusion in vivo. Two-colour single-molecule localisation microscopy of TOCA-1 and Ena supports their nanoscale association. TOCA-1 clusters promote filopodial protrusion and this depends on a functional TOCA-1 SH3 domain and activation of Cdc42, which we perturbed using the small-molecule inhibitor CASIN. We propose that TOCA-1 clusters act independently of membrane curvature to recruit and promote Ena activity for filopodial protrusion.

Description

Peer reviewed: True


Acknowledgements: We thank Asha Dwivedy for help with eye primordia electroporation and dissection, Jonathan Gadsby for helping with affinity purification of the anti-TOCA-1 antibody and Marc Kirschner (Harvard Medical School, Boston, MA, USA) for supplying the anti-Diaph3 antibody. We would like to thank Richard Butler from the Gurdon Institute Imaging Facility for valuable discussions.


Publication status: Published


Funder: Biochemical Society; doi: http://dx.doi.org/10.13039/100005849


Funder: University of Cambridge; doi: http://dx.doi.org/10.13039/501100000735

Keywords

Actin, Growth cone, Migration, Actins, Pseudopodia, Carrier Proteins, Neurons, Formins

Journal Title

J Cell Sci

Conference Name

Journal ISSN

0021-9533
1477-9137

Volume Title

137

Publisher

The Company of Biologists
Sponsorship
Wellcome Trust (219482/Z/19/Z)
Wellcome Trust (095829/Z/11/Z)
Isaac Newton Trust (Minute 1106(v))
Cancer Research Uk (None)
Wellcome Trust (092096/Z/10/Z)
Wellcome Trust (099740/Z/12/Z)