Regulation of the serotonin transporter by interacting proteins.
The serotonin transporter (SERT) plays a critical role in the maintenance of normal neurotransmission by serotonin [5-hydroxytryptamine (5-HT)]. Recent evidence suggests that SERT and other neurotransmitter transporters are tightly regulated. Activation of protein kinase C results in a decrease in SERT-mediated 5-HT uptake, which is due to an internalization of the transporter. However, to date little is known about the mechanism and proteins involved in the down-regulation of the transporter. One candidate SERT-regulatory protein is the SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor) protein, syntaxin 1A (Syn1A), which has recently been implicated in the regulation of ion channels as well as the SERT-related gamma-aminobutyric acid- and glycine-transporters. Using 5-HT uptake assays, confocal microscopy and glutathione S-transferase (GST) pull-down assays we showed that Syn1A also interacts with SERT and alters the subcellular localization of the transporter, resulting in a reduction of 5-HT transport. In addition, we have used the yeast two-hybrid system to search for novel regulatory proteins that interact with the cytoplasmic N-terminal domain of SERT. By screening rat brain cDNA library we have identified six potential SERT-binding proteins. Here we also present progress towards the elucidation of the biological relevance of these proteins and their potential role for the regulation of the serotonin transporter.
Haase
J
J
Biochemistry Department, Trinity College, Dublin 2, Ireland. jhaase@tcd.ie
Killian
A M
AM
Magnani
F
F
Williams
C
C
D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism* / Q000502:physiology*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism* / Q000502:physiology*; D026901:Membrane Transport Proteins; D008856:Microscopy, Fluorescence; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport; D012701:Serotonin / Q000494:pharmacology; D050486:Serotonin Plasma Membrane Transport Proteins; D050827:Syntaxin 1; D014162:Transfection; D020798:Two-Hybrid System Techniques
D000954:Antigens, Surface; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493230:SLC6A4 protein, human; C494212:STX1A protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; C494213:Stx1a protein, rat; D050827:Syntaxin 1; D012701:Serotonin; D011493:Protein Kinase C