title: Overlapping functions of stonin 2 and SV2 in sorting of the calcium sensor synaptotagmin 1 to synaptic vesicles.
abstract: Neurotransmission involves the calcium-regulated exocytic fusion of synaptic vesicles (SVs) and the subsequent retrieval of SV membranes followed by reformation of properly sized and shaped SVs. An unresolved question is whether each SV protein is sorted by its own dedicated adaptor or whether sorting is facilitated by association between different SV proteins. We demonstrate that endocytic sorting of the calcium sensor synaptotagmin 1 (Syt1) is mediated by the overlapping activities of the Syt1-associated SV glycoprotein SV2A/B and the endocytic Syt1-adaptor stonin 2 (Stn2). Deletion or knockdown of either SV2A/B or Stn2 results in partial Syt1 loss and missorting of Syt1 to the neuronal surface, whereas deletion of both SV2A/B and Stn2 dramatically exacerbates this phenotype. Selective missorting and degradation of Syt1 in the absence of SV2A/B and Stn2 impairs the efficacy of neurotransmission at hippocampal synapses. These results indicate that endocytic sorting of Syt1 to SVs is mediated by the overlapping activities of SV2A/B and Stn2 and favor a model according to which SV protein sorting is guarded by both cargo-specific mechanisms as well as association between SV proteins.
authors.affiliation: Department of Molecular Pharmacology and Cell Biology, Leibniz-Institut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany;
authors.forename: Natalie
authors.initials: N
authors.lastname: Kaempf
authors.affiliation: Department of Molecular Pharmacology and Cell Biology, Leibniz-Institut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany;
authors.forename: Gaga
authors.initials: G
authors.lastname: Kochlamazashvili
authors.affiliation: Department of Molecular Pharmacology and Cell Biology, Leibniz-Institut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany;
authors.forename: Dmytro
authors.initials: D
authors.lastname: Puchkov
authors.affiliation: Department of Molecular Pharmacology and Cell Biology, Leibniz-Institut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany;
authors.forename: Tanja
authors.initials: T
authors.lastname: Maritzen
authors.affiliation: Department of Pharmacology, University of Washington, Seattle, WA 98195;
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Bajjalieh
authors.affiliation: Department of Molecular Pharmacology and Cell Biology, Leibniz-Institut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany; Charite Universitätsmedizin, NeuroCure Cluster of Excellence, 10117 Berlin, Germany; haucke@fmp-berlin.de kononenko@fmp-berlin.de.
authors.forename: Natalia L
authors.initials: NL
authors.lastname: Kononenko
authors.affiliation: Department of Molecular Pharmacology and Cell Biology, Leibniz-Institut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany; Charite Universitätsmedizin, NeuroCure Cluster of Excellence, 10117 Berlin, Germany; Faculty of Biology, Chemistry, Pharmacy, Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany haucke@fmp-berlin.de kononenko@fmp-berlin.de.
authors.forename: Volker
authors.initials: V
authors.lastname: Haucke
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009474:Neurons / Q000378:metabolism; D013572:Synaptic Vesicles / Q000378:metabolism*; D050863:Synaptotagmin I / Q000378:metabolism*
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; C489614:Sv2a protein, mouse; D050863:Synaptotagmin I; C494311:Syt1 protein, mouse; C579576:stonin 2 protein, mouse; D002118:Calcium
keywords: calcium sensor; endocytosis; knockout mice; neurotransmission; synaptic vesicle protein sorting