Cell-type-specific limitation on in vivo serotonin storage following ectopic expression of the Drosophila serotonin transporter, dSERT.
The synaptic machinery for neurotransmitter storage is cell-type specific. Although most elements of biosynthesis and transport have been identified, it remains unclear whether additional factors may be required to maintain this specificity. The Drosophila serotonin transporter (dSERT) is normally expressed exclusively in serotonin (5-HT) neurons in the CNS. Here we examine the effects of ectopic transcriptional expression of dSERT in the Drosophila larval CNS. We find a surprising limitation on 5-HT storage following ectopic expression of dSERT and green fluorescence protein-tagged dSERT (GFP-dSERT). When dSERT transcription is driven ectopically in the CNS, 5-HT is detectable only in 5-HT, dopamine (DA), and a very limited number of additional neurons. Addition of exogenous 5-HT does not dramatically broaden neuronal storage sites, so this limitation is only partly due to restricted intercellular diffusion of 5-HT. Furthermore, this limitation is not due to gross mislocalization of dSERT, because cells lacking or containing 5-HT show similar levels and subcellular distribution of GFP-dSERT protein, nor is it due to lack of the vesicular transporter, dVMAT. These data suggest that a small number of neurons selectively express factor(s) required for 5-HT storage, and potentially for function of dSERT.
Department of Biology, University of Virginia, Charlottesville, Virginia 22904, USA.
Sang Ki
SK
Park
Rebecca
R
George
Ying
Y
Cai
H Y
HY
Chang
D E
DE
Krantz
Florence
F
Friggi-Grelin
Serge
S
Birman
Jay
J
Hirsh
D000818:Animals; D002451:Cell Compartmentation / Q000187:drug effects / Q000502:physiology; D002490:Central Nervous System / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D049452:Green Fluorescent Proteins; D007814:Larva / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D022161:Transport Vesicles / Q000378:metabolism
D029721:Drosophila Proteins; C493233:SerT protein, Drosophila; D050486:Serotonin Plasma Membrane Transport Proteins; D049452:Green Fluorescent Proteins; D012701:Serotonin; D004298:Dopamine