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The drebrin/EB3 pathway regulates cytoskeletal dynamics to drive neuritogenesis in embryonic cortical neurons

Research output: Contribution to journalArticlepeer-review

Thanushiyan Poobalasingam, Francesca Bianco, Fazal Oozeer, Phillip R Gordon-Weeks

Original languageEnglish
Number of pages18
JournalJournal of Neurochemistry
Volume160
Issue number2
DOIs
E-pub ahead of print20 Sep 2021

Bibliographical note

Funding Information: We thank Avery August for the kind gift of the K270 M, K271 M drebrin‐GFP mutant and Eisai Ltd for eribulin. The mAb DSHB‐GFP‐1D2 developed by the Developmental Studies Hybridoma Bank was obtained from the Developmental Studies Hybridoma Bank, created by the NICHD of the NIH and maintained at The University of Iowa, Department of Biology, Iowa City, IA 52242. This work was supported by grants from the Biotechnology and Biological Sciences Research Council and the Medical Research Council. Francesca Bianco was supported by an Anatomical Society Undergraduate Summer Vacation Scholarship. Publisher Copyright: © 2021 The Authors. Journal of Neurochemistry published by John Wiley & Sons Ltd on behalf of International Society for Neurochemistry.

King's Authors

Abstract

Co-ordinating the dynamic behaviour of actin filaments (F-actin) and microtubules in filopodia is an important underlying process in neuritogenesis, but the molecular pathways involved are ill-defined. The drebrin/end-binding protein 3 (EB3) pathway is a candidate pathway for linking F-actin to microtubules in filopodia. Drebrin binds F-actin and, simultaneously, the microtubule-binding protein EB3 when bound to microtubule plus-ends. We assessed the effect on neuritogenesis of gain- or loss-of-function of proteins in the drebrin/EB3 pathway in rat embryonic cortical neurons in culture. Loss-of-function of drebrin by gene editing or pharmacological inhibition of drebrin binding to F-actin reduced the number of dynamic microtubules in the cell periphery and simultaneously delayed the initiation of neuritogenesis, whereas over-expression of drebrin induced supernumerary neurites. Similarly, loss of EB3 inhibited neuritogenesis, whereas loss of end-binding protein 1 (EB1), a related protein that does not bind to drebrin, did not affect neuritogenesis. Over-expression of EB3, but not EB1, induced supernumerary neurites. We discovered that EB3 is more proximally located at dynamic microtubule plus-ends than EB1 in growth cone filopodia allowing for continuous microtubule elongation as the drebrin/EB3 pathway zippers microtubules to F-actin in filopodia. Finally, we showed that preventing the entry of dynamic microtubules into filopodia using a pharmacological inhibitor of microtubule dynamics is associated with a loss of EB3, but not EB1, from microtubule plus-ends and a concurrent attenuation of neuritogenesis. Collectively, these findings support the idea that neuritogenesis depends on microtubule/F-actin zippering in filopodia orchestrated by the drebrin/EB3 pathway. (Figure presented.).

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