title: Synapsin knockdown is associated with decreased neurite outgrowth, functional synaptogenesis impairment, and fast high-frequency neurotransmitter release.
abstract: Synapsins (Syns) are an evolutionarily conserved family of synaptic vesicle-associated proteins related to fine tuning of synaptic transmission. Studies with mammals have partially clarified the different roles of Syns; however, the presence of different genes and isoforms and the development of compensatory mechanisms hinder accurate data interpretation. Here, we use a simple in vitro monosynaptic Helix neuron connection, reproducing an in vivo physiological connection as a reliable experimental model to investigate the effects of Syn knockdown. Cells overexpressing an antisense construct against Helix Syn showed a time-dependent decrease of Syn immunostaining, confirming protein loss. At the morphological level, Syn-silenced cells showed a reduction in neurite linear outgrowth and branching and in the size and number of synaptic varicosities. Functionally, Syn-silenced cells presented a reduced ability to form synaptic connections; however, functional chemical synapses showed similar basal excitatory postsynaptic potentials and similar short-term plasticity paradigms. In addition, Syn-silenced cells presented faster neurotransmitter release and decreased postsynaptic response toward the end of long tetanic presynaptic stimulations, probably related to an impairment of the synaptic vesicle trafficking resulting from a different vesicle handling, with an increased readily releasable pool and a compromised reserve pool.
authors.affiliation: Department of Neuroscience, Section of Physiology, University of Turin, Turin, Italy.|Department of Physiology, School of Medicine, University of Costa Rica, San José, Costa Rica.
authors.forename: Oscar
authors.initials: O
authors.lastname: Brenes
authors.affiliation: Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Carlo Natale Giuseppe
authors.initials: CN
authors.lastname: Giachello
authors.affiliation: Department of Experimental Medicine, University of Genova, Genova, Italy.
authors.forename: Anna Margherita
authors.initials: AM
authors.lastname: Corradi
authors.affiliation: Department of Neuroscience, Section of Physiology, University of Turin, Turin, Italy.|National Institute of Neuroscience, Turin, Italy.
authors.forename: Mirella
authors.initials: M
authors.lastname: Ghirardi
authors.affiliation: Department of Neuroscience, Section of Physiology, University of Turin, Turin, Italy.|National Institute of Neuroscience, Turin, Italy.
authors.forename: Pier Giorgio
authors.initials: PG
authors.lastname: Montarolo
mesh_terms: D000200:Action Potentials / Q000235:genetics; D000818:Animals; D002478:Cells, Cultured; D017952:Ganglia, Invertebrate / Q000166:cytology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006372:Helix, Snails; D008845:Microinjections; D016501:Neurites / Q000502:physiology*; D055495:Neurogenesis / Q000235:genetics*; D009473:Neuronal Plasticity / Q000187:drug effects / Q000235:genetics; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology; D013569:Synapses / Q000502:physiology*; D016704:Synapsins / Q000235:genetics / Q000378:metabolism*; D014161:Transduction, Genetic
chemical_list: D018377:Neurotransmitter Agents; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D016704:Synapsins; D049452:Green Fluorescent Proteins; D012701:Serotonin
keywords: NCBI taxonomic ID: 6535; RRID:AB_11181145; RRID:nif-0000-00313; RRID:nif-0000-30467; RRID:rid_000081; RRID:rid_000085; invertebrates; neurites; synapses; synapsins; synaptic transmission