Microtubules are not required to generate a nascent axon in embryonic spinal neurons in vivo

TY - JOUR

T1 - Microtubules are not required to generate a nascent axon in embryonic spinal neurons in vivo

AU - Moore, Rachel E.

AU - Pop, Sînziana

AU - Alleyne, Caché

AU - Clarke, Jonathan D.W.

N1 - Funding Information: R.E.M. and J.C. were supported by the Wellcome Trust (102895/Z/13/Z). S.P. was supported by an MRC studentship. Thanks to Christopher Rookyard for the image in Fig  6A , Corinne Houart's lab for kindly providing the α‐tubulin antibody, and to past and present members of the Clarke lab and CDN for constructive feedback and discussion. Publisher Copyright: ©2022 The Authors. Published under the terms of the CC BY 4.0 license.

PY - 2022/11/7

Y1 - 2022/11/7

N2 - Our understanding of the cell behaviours and cytoskeletal requirements of axon formation is largely derived from in vitro models but how these relate to axon formation in vivo is not clear. In vitro, neurons progress through a well-defined multineurite stage to form an axon and both actin and microtubules cooperate to drive the first steps in neurite and axon morphogenesis. However, these steps are not recapitulated in vivo, and it is not clear whether the underlying cell biological mechanisms may differ also. Here, we investigate the mechanisms that regulate axon formation in embryonic zebrafish spinal neurons in vivo. We find microtubule organising centres are located distant from the site of axon initiation, and microtubule plus-ends are not enriched in the axon during axon initiation. Focal F-actin accumulation precedes axon formation, and we find that nocodazole-treated neurons with no detectable microtubules are still able to form nascent axonal protrusions that are approximately 10-μm long, dilated and relatively long-lived. We suggest spinal axon formation in vivo is fundamentally different from axon formation in in vitro models.

AB - Our understanding of the cell behaviours and cytoskeletal requirements of axon formation is largely derived from in vitro models but how these relate to axon formation in vivo is not clear. In vitro, neurons progress through a well-defined multineurite stage to form an axon and both actin and microtubules cooperate to drive the first steps in neurite and axon morphogenesis. However, these steps are not recapitulated in vivo, and it is not clear whether the underlying cell biological mechanisms may differ also. Here, we investigate the mechanisms that regulate axon formation in embryonic zebrafish spinal neurons in vivo. We find microtubule organising centres are located distant from the site of axon initiation, and microtubule plus-ends are not enriched in the axon during axon initiation. Focal F-actin accumulation precedes axon formation, and we find that nocodazole-treated neurons with no detectable microtubules are still able to form nascent axonal protrusions that are approximately 10-μm long, dilated and relatively long-lived. We suggest spinal axon formation in vivo is fundamentally different from axon formation in in vitro models.

KW - actin

KW - axon initiation

KW - microtubules

KW - neuronal differentiation

KW - zebrafish

UR - http://www.scopus.com/inward/record.url?scp=85139153086&partnerID=8YFLogxK

U2 - 10.15252/embr.202152493

DO - 10.15252/embr.202152493

M3 - Article

C2 - 36194673

AN - SCOPUS:85139153086

SN - 1469-221X

VL - 23

JO - EMBO Reports

JF - EMBO Reports

IS - 11

M1 - e52493

ER -