Filopodial dynamics and growth cone stabilization in Drosophila visual circuit development

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Abstract

Filopodial dynamics are thought to control growth cone guidance, but the types and roles of growth cone dynamics underlying neural circuit assembly in a living brain are largely unknown. To address this issue, we have developed long-term, continuous, fast and high-resolution imaging of growth cone dynamics from axon growth to synapse formation in cultured Drosophila brains. Using R7 photoreceptor neurons as a model we show that >90% of the growth cone filopodia exhibit fast, stochastic dynamics that persist despite ongoing stepwise layer formation. Correspondingly, R7 growth cones stabilize early and change their final position by passive dislocation. N-Cadherin controls both fast filopodial dynamics and growth cone stabilization. Surprisingly, loss of N-Cadherin causes no primary targeting defects, but destabilizes R7 growth cones to jump between correct and incorrect layers. Hence, growth cone dynamics can influence wiring specificity without a direct role in target recognition and implement simple rules during circuit assembly.

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Mehmet Neset Özel

Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States

Competing interests
The authors declare that no competing interests exist.
Marion Langen

Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States

Competing interests
The authors declare that no competing interests exist.
Bassem A Hassan

Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, Leuven, Belgium

Competing interests
The authors declare that no competing interests exist.
P Robin Hiesinger

Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States

For correspondence
robin.hiesinger@fu-berlin.de

Competing interests
The authors declare that no competing interests exist.

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