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UNC-46 is required for trafficking of the vesicular GABA transporter

Nature Neuroscience volume 10, pages 846–853 (2007)Cite this article

Abstract

Mutations in unc-46 in Caenorhabditis elegans cause defects in all behaviors that are mediated by GABA. Here we show that UNC-46 is a sorting factor that localizes the vesicular GABA transporter to synaptic vesicles. The UNC-46 protein is related to the LAMP (lysosomal associated membrane protein) family of proteins and is localized at synapses. In unc-46 mutants, the vesicular transporter is not found specifically in synaptic vesicles but rather is diffusely spread along the axon. Mislocalization of the transporter severely reduces the frequency of miniature currents, but the remaining currents are normal in amplitude. Because the number of synaptic vesicles is not depleted, it is likely that only a fraction of vesicles harbor the transporter in unc-46 mutants. Our data indicate that the transporter and UNC-46 have mutual roles in sorting. The vesicular GABA transporter recruits UNC-46 to synaptic vesicle precursors in the cell body, and UNC-46 sorts the transporter at the cell body and during endocytosis at the synapse.

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Figure 1: UNC-46 phylogenetic tree and predicted secondary structure.
Figure 2: The unc-46 gene is expressed in GABA neurons and is not required for neuron development.
Figure 3: UNC-46 is localized at synapses.
Figure 4: Localization of VGAT in unc-46 and unc-25 mutants.
Figure 5: Ultrastructural analysis of unc-46 mutants.
Figure 6: Electrophysiological analysis of unc-46 mutants.
Figure 7: Locomotion of unc-46 mutants is rescued by overexpression of VGAT.

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Acknowledgements

We thank J. White for use of his worm tracking system, M. Gu for the GFP-tagged synaptotagmin strain, the C. elegans Genome Center for strains, the Sanger Center for cosmids, Y. Kohara for the unc-46 cDNA, J. Shine for unc-46 mapping data, J. Thomas for the Brugia gene prediction, and D. Joshi and J. Huang for technical assistance.

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Authors and Affiliations

  1. Howard Hughes Medical Institute and the Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, 84112-0840, Utah, USA

    Kim Schuske, Mark T Palfreyman, Shigeki Watanabe & Erik M Jorgensen

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  1. Kim Schuske
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  4. Erik M Jorgensen
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Contributions

M.T.P. performed the electrophysiology experiments, S.W. performed the electron microscopy experiments and K.S. performed all other experiments and wrote the paper with E.M.J. and with help from M.T.P.

Corresponding author

Correspondence to Erik M Jorgensen.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Fig. 1

unc-46 cloning. (PDF 136 kb)

Supplementary Fig. 2

UNC-46 homolog alignment. (PDF 334 kb)

Supplementary Fig. 3

GABA nervous system structure is normal in unc-46 mutants. (PDF 167 kb)

Supplementary Fig. 4

Model for UNC-46 protein function. (PDF 101 kb)

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Schuske, K., Palfreyman, M., Watanabe, S. et al. UNC-46 is required for trafficking of the vesicular GABA transporter. Nat Neurosci 10, 846–853 (2007). https://doi.org/10.1038/nn1920

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