The carcinine transporter CarT is required in Drosophila photoreceptor neurons to sustain histamine recycling

Abstract
Article and author information
Metrics

Abstract

Synaptic transmission from Drosophila photoreceptors to lamina neurons requires recycling of histamine neurotransmitter. Synaptic histamine is cleared by uptake into glia and conversion into carcinine, which functions as transport metabolite. How carcinine is transported from glia to photoreceptor neurons remains unclear. In a targeted RNAi screen for genes involved in this pathway we identified carT, which encodes a member of the SLC22A transporter family. CarT expression in photoreceptors is necessary and sufficient for fly vision and behavior. In the lamina of carT flies, carcinine accumulates. Wild-type levels are restored by photoreceptor-specific expression of CarT, and endogenous tagging suggests CarT localizes to synaptic endings. Heterologous expression of CarT in S2 cells is sufficient for carcinine uptake, demonstrating the ability of CarT to utilize carcinine as a transport substrate. Together, our results demonstrate that CarT transports the histamine metabolite carcinine into photoreceptor neurons, thus contributing an essential step in the histamine-carcinine cycle.

Article and author information

Author details

Drew Stenesen

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

Competing interests
The authors declare that no competing interests exist.
Andrew T Moehlman

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

Competing interests
The authors declare that no competing interests exist.
Helmut Krämer

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

For correspondence
helmut.kramer@utsouthwestern.edu

Competing interests
The authors declare that no competing interests exist.

Copyright

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.