ABSTRACT
Nervous wreck (Nwk) is a conserved F-BAR protein that attenuates synaptic growth and promotes synaptic function in Drosophila. In an effort to understand how Nwk carries out its dual roles, we isolated interacting proteins using mass spectrometry. We report a conserved interaction between Nwk proteins and BAR-SH3 sorting nexins, a family of membrane-binding proteins implicated in diverse intracellular trafficking processes. In mammalian cells, BAR-SH3 sorting nexins induce plasma membrane tubules that localize NWK2, consistent with a possible functional interaction during the early stages of endocytic trafficking. To study the role of BAR-SH3 sorting nexins in vivo, we took advantage of the lack of genetic redundancy in Drosophila and employed CRISPR-based genome engineering to generate null and endogenously tagged alleles of SH3PX1. SH3PX1 localizes to neuromuscular junctions where it regulates synaptic ultrastructure, but not synapse number. Consistently, neurotransmitter release was significantly diminished in SH3PX1 mutants. Double-mutant and tissue-specific-rescue experiments indicate that SH3PX1 promotes neurotransmitter release presynaptically, at least in part through functional interactions with Nwk, and might act to distinguish the roles of Nwk in regulating synaptic growth and function.
Footnotes
Competing interests
The authors declare no competing or financial interests.
Author contributions
K.M.O.-G. and F.P.U. conceived of the study, performed experiments, analyzed data and wrote the manuscript. J.J.B., K.L.W., S.L.S., R.M.B., S.J.H., L.H., K.L.T., E.W.D. and G.B.G. executed experiments and analyzed data.
Funding
This work was funded by grants from the National Institute of Neurological Disorders and Stroke, National Institutes of Health (NIH) [grant numbers NS078179 and NS060985 (to K.M.O.-G.); and NS080928 (to E.W.D.)]; an NIH training grant [grant number GM007507 (to K.L.T.)]; and a National Science Foundation Graduate Research Fellowship to J.J.B. Deposited in PMC for immediate release.
Supplementary information
Supplementary information available online at http://jcs.biologists.org/lookup/suppl/doi:10.1242/jcs.178699/-/DC1
- Received August 5, 2015.
- Accepted November 11, 2015.
- © 2016. Published by The Company of Biologists Ltd
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.