title: Ubiquitination acutely regulates presynaptic neurotransmitter release in mammalian neurons.
abstract: The ubiquitin proteasome system (UPS) plays a crucial role in modulating synaptic physiology both presynaptically and postsynaptically, but the regulatory mechanisms remain obscure. To determine acute effects of proteasome inhibition on neurotransmission, we performed whole-cell voltage-clamp recordings from cultured rodent hippocampal neurons. We find that proteasome inhibitors induce a strikingly fast, severalfold increase in the frequency of both miniature (mini) and spontaneous synaptic currents at excitatory and inhibitory synapses. The lack of change in mini amplitude and kinetics indicates a presynaptic site of action. This effect does not depend on increased levels of presynaptic proteins, previously suggested as proteasomal targets. Furthermore, blockade of the UPS using E1-activating enzyme inhibitors also increases mini frequency, demonstrating that accumulation of ubiquitinated proteins is not required. Overall, these data suggest that the UPS not only orchestrates protein turnover, but also dynamically regulates the activity state of presynaptic proteins, thus crucially shaping synaptic transmission.
authors.affiliation: Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, Los Angeles, California 90095-1763, USA.
authors.forename: Gina V
authors.initials: GV
authors.lastname: Rinetti
authors.forename: Felix E
authors.initials: FE
authors.lastname: Schweizer
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D025801:Ubiquitin / Q000037:antagonists & inhibitors / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects / Q000502:physiology*
chemical_list: D004791:Enzyme Inhibitors; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; D061988:Proteasome Inhibitors; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex