title: Serotonin Transporter Associated Protein Complexes Are Enriched in Synaptic Vesicle Proteins and Proteins Involved in Energy Metabolism and Ion Homeostasis.
abstract: The serotonin transporter (SERT) mediates Na+-dependent high-affinity serotonin uptake and plays a key role in regulating extracellular serotonin concentration in the brain and periphery. To gain novel insight into SERT regulation, we conducted a comprehensive proteomics screen to identify components of SERT-associated protein complexes in the brain by employing three independent approaches. In vivo SERT complexes were purified from rat brain using an immobilized high-affinity SERT ligand, amino-methyl citalopram. This approach was combined with GST pulldown and yeast two-hybrid screens using N- and C-terminal cytoplasmic transporter domains as bait. Potential SERT associated proteins detected by at least two of the interaction methods were subjected to gene ontology analysis resulting in the identification of functional protein clusters that are enriched in SERT complexes. Prominent clusters include synaptic vesicle proteins, as well as proteins involved in energy metabolism and ion homeostasis. Using subcellular fractionation and electron microscopy we provide further evidence that SERT is indeed associated with synaptic vesicle fractions, and colocalizes with small vesicular structures in axons and axon terminals. We also show that SERT is found in close proximity to mitochondrial membranes in both, hippocampal and neocortical regions. We propose a model of the SERT interactome, in which SERT is distributed between different subcellular compartments through dynamic interactions with site-specific protein complexes. Finally, our protein interaction data suggest novel hypotheses for the regulation of SERT activity and trafficking, which ultimately impact on serotonergic neurotransmission and serotonin dependent brain functions.
authors.affiliation: UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin , Dublin 4, Ireland.
authors.forename: Jana
authors.identifier: 0000-0002-5949-8355
authors.initials: J
authors.lastname: Haase
authors.affiliation: UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin , Dublin 4, Ireland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Grudzinska-Goebel
authors.affiliation: UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin , Dublin 4, Ireland.|Department of Clinical Medicine, Translational Neuropsychiatry Unit, Aarhus University , Risskov DK-8240, Denmark.
authors.forename: Heidi Kaastrup
authors.initials: HK
authors.lastname: Müller
authors.affiliation: Institute of Integrative Neuroanatomy, Charité University Medicine Berlin , 10117 Berlin, Germany.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Münster-Wandowski
authors.affiliation: UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin , Dublin 4, Ireland.
authors.forename: Elysian
authors.initials: E
authors.lastname: Chow
authors.affiliation: Proteomic Core Facility, UCD Conway Institute, School of Medicine and Medical Sciences, University College Dublin , Dublin 4, Ireland.
authors.forename: Kieran
authors.initials: K
authors.lastname: Wynne
authors.affiliation: Department of Neurobiology, Max-Planck-Institute for Biophysical Chemistry , 37077 Göttingen, Germany.
authors.forename: Zohreh
authors.initials: Z
authors.lastname: Farsi
authors.affiliation: Institute of Integrative Neuroanatomy, Charité University Medicine Berlin , 10117 Berlin, Germany.
authors.forename: Johannes-Friedrich
authors.initials: JF
authors.lastname: Zander
authors.affiliation: Institute of Integrative Neuroanatomy, Charité University Medicine Berlin , 10117 Berlin, Germany.
authors.forename: Gudrun
authors.initials: G
authors.lastname: Ahnert-Hilger
mesh_terms: D000818:Animals; D004734:Energy Metabolism / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology*; D017136:Ion Transport / Q000502:physiology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*
chemical_list: D050486:Serotonin Plasma Membrane Transport Proteins
keywords: Serotonin transporter; hippocampus; mitochondria; protein−protein interactions; proteomics; synaptic vesicle