The ability of neurons to generate multiple arbor terminals from a single axon is crucial for establishing proper neuronal wiring. Although growth and retraction of arbor terminals are differentially regulated within the axon, the mechanisms by which neurons locally control their structure remain largely unknown. In the present study, we found that the kinesin-1 (Kif5 proteins) head domain (K5H) preferentially marks a subset of arbor terminals. Time-lapse imaging clarified that these arbor terminals were more stable than others, because of a low retraction rate. Local inhibition of kinesin-1 in the arbor terminal by chromophore-assisted light inactivation (CALI) enhanced the retraction rate. The microtubule turnover was locally regulated depending on the length from the branching point to the terminal end, but did not directly correlate with the presence of K5H. By contrast, F-actin signal values in arbor terminals correlated spatiotemporally with K5H, and inhibition of actin turnover prevented retraction. Results from the present study reveal a new system mediated by kinesin-1 sorting in axons that differentially controls stability of arbor terminals.
The authors declare no competing or financial interests.
T.S., K.M., N.S. and Y.K. analyzed axonal morphology and microtubules, and T.I. and M.K. analyzed F-actin. H.T. contributed to the data analysis, and M.S. and Y.K. designed the experiments and wrote the paper.
This work was supported by a Ministry of Education, Culture, Sports, Science, and Technology (MEXT) KAKENHI Grant-in-Aid for Scientific Research on Innovative Areas, Nanomedicine Molecular Science [grant numbers 24107509 and 26107707 to Y.K.].
Supplementary information available online at http://jcs.biologists.org/lookup/doi/10.1242/jcs.183806.supplemental
- Received November 23, 2015.
- Accepted August 2, 2016.
- © 2016. Published by The Company of Biologists Ltd