an-optical-assay-for-synaptic-vesicle-recycling-cultured-neurons

An Optical Assay for Synaptic Vesicle Recycling in Cultured Neurons Overexpressing Presynaptic Proteins

At active presynaptic nerve terminals, synaptic vesicles undergo cycles of exo- and endocytosis. During recycling, the luminal domains of SV transmembrane ...

quantifying-heterogeneous-distribution-synaptic-protein-mouse-brain

Quantifying the Heterogeneous Distribution of a Synaptic Protein in the Mouse Brain Using Immunofluorescence

The presence, absence, or levels of specific synaptic proteins can severely influence synaptic transmission. In addition to elucidating the function of a ...

University Medical Centre Göttingen

University Medical Center Göttingen

Endbulb of Held terminals of auditory nerve fibers (ANF) transmit auditory information at hundreds per second to bushy cells (BCs) in the anteroventral cochlear nucleus (AVCN). Here, we studied the structure and function of endbulb synapses in mice that lack the presynaptic scaffold bassoon and exhibit reduced ANF input into the AVCN. Endbulb terminals and active zones were normal in number and vesicle complement. Postsynaptic densities, quantal size and vesicular release probability were increased while vesicle replenishment and the standing pool of readily releasable vesicles were reduced. These opposing effects canceled each other out for the first evoked EPSC, which showed unaltered amplitude. We propose that ANF activity deprivation drives homeostatic plasticity in the AVCN involving synaptic upscaling and increased intrinsic BC excitability. In vivo recordings from individual mutant BCs demonstrated a slightly improved response at sound onset compared to ANF, likely reflecting the combined effects of ANF convergence and homeostatic plasticity. Further, we conclude that bassoon promotes vesicular replenishment and, consequently, a large standing pool of readily releasable synaptic vesicles at the endbulb synapse.

Bassoon-disruption slows vesicle replenishment and induces homeostatic plasticity at a CNS synapse.

Mutations in the human homolog of the Drosophila gene Rogdi cause Kohlschütter-Tönz syndrome. This disorder is characterised by amelogenesis imperfecta, as well as severe neurological symptoms including epilepsy and psychomotor delay. However, little is known about the protein encoded by Rogdi, and hence the pathogenic mechanisms underlying Kohlschütter-Tönz syndrome have remained elusive. Using immunofluorescence of rat cultured hippocampal neurons and brain sections we find that Rogdi is enriched at synaptic sites. In addition, recombinant GFP-Rogdi expressed in cultured neurons was efficiently targeted to presynaptic sites, where it colocalised with the presynaptic scaffolding protein Bassoon and the synaptic vesicle markers Synaptophysin, Synapsin-1, VAMP2/Synaptobrevin and Mover. Our data indicate that GFP-Rogdi harbours efficient signals for presynaptic targeting, and that Rogdi is a presynaptic protein. Thus, the neurological symptoms associated with Kohlschütter-Tönz syndrome may arise from presynaptic dysfunction.

Thomas Dresbach

Institute for Anatomy and Embryology

University Medical Centre Göttingen

An Optical Assay for Synaptic Vesicle Recycling in Cultured Neurons Overexpressing Presynaptic Proteins

Quantifying the Heterogeneous Distribution of a Synaptic Protein in the Mouse Brain Using Immunofluorescence

Thomas Dresbach

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Institute for Anatomy and Embryology

University Medical Centre Göttingen

An Optical Assay for Synaptic Vesicle Recycling in Cultured Neurons Overexpressing Presynaptic Proteins

Quantifying the Heterogeneous Distribution of a Synaptic Protein in the Mouse Brain Using Immunofluorescence

Institute for Anatomy and Embryology