title: Cryo-electron tomography reveals a critical role of RIM1α in synaptic vesicle tethering.
abstract: Synaptic vesicles are embedded in a complex filamentous network at the presynaptic terminal. Before fusion, vesicles are linked to the active zone (AZ) by short filaments (tethers). The identity of the molecules that form and regulate tethers remains unknown, but Rab3-interacting molecule (RIM) is a prominent candidate, given its central role in AZ organization. In this paper, we analyzed presynaptic architecture of RIM1α knockout (KO) mice by cryo-electron tomography. In stark contrast to previous work on dehydrated, chemically fixed samples, our data show significant alterations in vesicle distribution and AZ tethering that could provide a structural basis for the functional deficits of RIM1α KO synapses. Proteasome inhibition reversed these structural defects, suggesting a functional recovery confirmed by electrophysiological recordings. Altogether, our results not only point to the ubiquitin-proteasome system as an important regulator of presynaptic architecture and function but also show that the tethering machinery plays a critical role in exocytosis, converging into a structural model of synaptic vesicle priming by RIM1α.
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
authors.forename: Rubén
authors.initials: R
authors.lastname: Fernández-Busnadiego
authors.forename: Shoh
authors.initials: S
authors.lastname: Asano
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Oprisoreanu
authors.forename: Eri
authors.initials: E
authors.lastname: Sakata
authors.forename: Michael
authors.initials: M
authors.lastname: Doengi
authors.forename: Zdravko
authors.initials: Z
authors.lastname: Kochovski
authors.forename: Magdalena
authors.initials: M
authors.lastname: Zürner
authors.forename: Valentin
authors.initials: V
authors.lastname: Stein
authors.forename: Susanne
authors.initials: S
authors.lastname: Schoch
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumeister
authors.forename: Vladan
authors.initials: V
authors.lastname: Lucić
mesh_terms: D000818:Animals; D005089:Exocytosis / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D007976:Leupeptins / Q000494:pharmacology; D008561:Membrane Fusion / Q000187:drug effects; D051379:Mice; D018345:Mice, Knockout; D046988:Proteasome Endopeptidase Complex / Q000502:physiology; D061988:Proteasome Inhibitors / Q000494:pharmacology; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D014054:Tomography / Q000379:methods
chemical_list: D007976:Leupeptins; D061988:Proteasome Inhibitors; C491490:Rims1 protein, mouse; D046988:Proteasome Endopeptidase Complex; D019204:GTP-Binding Proteins; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde