R7 photoreceptor axon targeting depends on the relative levels of lost and found expression in R7 and its synaptic partners
Abstract
As neural circuits form, growing processes select the correct synaptic partners through interactions between cell surface proteins. The presence of such proteins on two neuronal processes may lead to either adhesion or repulsion; however, the consequences of mismatched expression have rarely been explored. Here we show that the Drosophila CUB-LDL protein Lost and found (Loaf) is required in the UV-sensitive R7 photoreceptor for normal axon targeting only when Loaf is also present in its synaptic partners. Although targeting occurs normally in loaf mutant animals, removing loaf from photoreceptors or expressing it in their postsynaptic neurons Tm5a/b or Dm9 in a loaf mutant causes mistargeting of R7 axons. Loaf localizes primarily to intracellular vesicles including endosomes. We propose that Loaf regulates the trafficking or function of one or more cell surface proteins, and an excess of these proteins on the synaptic partners of R7 prevents the formation of stable connections.
Data availability
All data generated or analyzed during this study are included in the manuscript and supporting files.
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Author details
Funding
National Institutes of Health (R01GM089799)
- Jessica E Treisman
National Institutes of Health (R01NS112211)
- Jessica E Treisman
National Institutes of Health (F31EY025568)
- Jessica Douthit
Human Frontier Science Program ((LT000757/2017)
- Isabel Holguera
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Carol A Mason, Columbia University, United States
Version history
- Received: December 18, 2020
- Accepted: May 17, 2021
- Accepted Manuscript published: May 18, 2021 (version 1)
- Version of Record published: June 15, 2021 (version 2)
Copyright
© 2021, Douthit et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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