LOVIT Is a Putative Vesicular Histamine Transporter Required in Drosophila for Vision

Abstract

Summary: Classical fast neurotransmitters are loaded into synaptic vesicles and concentrated by the action of a specific vesicular transporter before being released from the presynaptic neuron. In Drosophila, histamine is distributed mainly in photoreceptors, where it serves as the main neurotransmitter for visual input. In a targeted RNAi screen for neurotransmitter transporters involved in concentrating photoreceptor synaptic histamine, we identified an SLC45 transporter protein, LOVIT (loss of visual transmission). LOVIT is prominently expressed in photoreceptor synaptic vesicles and is required for Drosophila visual neurotransmission. Null mutations of lovit severely reduced the concentration of histamine in photoreceptor terminals. These results demonstrate a LOVIT-dependent mechanism, maintaining the synaptic concentration of histamine, and provide evidence for a histamine vesicular transporter besides the vesicular monoamine transporter (VMAT) family. : Xu et al. identify a member of the SLC45 transporter family, LOVIT, expressed in photoreceptor synaptic vesicles. The authors further demonstrate that LOVIT is required for maintaining the synaptic vesicular concentration of histamine at the Drosophila photoreceptor terminal and supports the high rates of histamine release in fly visual neurotransmission. Keywords: vesicular transporter, neurotransmitter concentration, histamine, synaptic transmission