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https://www.readbyqxmd.com/read/29163046/rim-binding-protein-2-promotes-a-large-number-of-cav1-3-ca-2-channels-and-contributes-to-fast-synaptic-vesicle-replenishment-at-hair-cell-active-zones
#1
Stefanie Krinner, Tanvi Butola, SangYong Jung, Carolin Wichmann, Tobias Moser
Ribbon synapses of inner hair cells (IHCs) mediate high rates of synchronous exocytosis to indefatigably track the stimulating sound with sub-millisecond precision. The sophisticated molecular machinery of the inner hair cell active zone realizes this impressive performance by enabling a large number of synaptic voltage-gated CaV1.3 Ca(2+)-channels, their tight coupling to synaptic vesicles (SVs) and fast replenishment of fusion competent SVs. Here we studied the role of RIM-binding protein 2 (RIM-BP2)-a multidomain cytomatrix protein known to directly interact with Rab3 interacting molecules (RIMs), bassoon and CaV1...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/29118709/piccolo-promotes-vesicle-replenishment-at-a-fast-central-auditory-synapse
#2
Tanvi Butola, Carolin Wichmann, Tobias Moser
Piccolo and Bassoon are the two largest cytomatrix of the active zone (CAZ) proteins involved in scaffolding and regulating neurotransmitter release at presynaptic active zones (AZs), but have long been discussed as being functionally redundant. We employed genetic manipulation to bring forth and segregate the role of Piccolo from that of Bassoon at central auditory synapses of the cochlear nucleus-the endbulbs of Held. These synapses specialize in high frequency synaptic transmission, ideally poised to reveal even subtle deficits in the regulation of neurotransmitter release upon molecular perturbation...
2017: Frontiers in Synaptic Neuroscience
https://www.readbyqxmd.com/read/29114208/classification-of-mouse-retinal-bipolar-cells-type-specific-connectivity-with-special-reference-to-rod-driven-aii-amacrine-pathways
#3
Yoshihiko Tsukamoto, Naoko Omi
We confirmed the classification of 15 morphological types of mouse bipolar cells by serial section transmission electron microscopy and characterized each type by identifying chemical synapses and gap junctions at axon terminals. Although whether the previous type 5 cells consist of two or three types was uncertain, they are here clustered into three types based on the vertical distribution of axonal ribbons. Next, while two groups of rod bipolar (RB) cells, RB1, and RB2, were previously proposed, we clarify that a half of RB1 cells have the intermediate characteristics, suggesting that these two groups comprise a single RB type...
2017: Frontiers in Neuroanatomy
https://www.readbyqxmd.com/read/29111973/otoferlin-acts-as-a-ca-2-sensor-for-vesicle-fusion-and-vesicle-pool-replenishment-at-auditory-hair-cell-ribbon-synapses
#4
Nicolas Antoine Michalski, Juan D Goutman, Sarah Marie Auclair, Jacques Boutet de Monvel, Margot Tertrais, Alice Emptoz, Alexandre Parrin, Sylvie Nouaille, Marc Guillon, Martin Sachse, Danica Ciric, Amel Bahloul, Jean-Pierre Hardelin, Roger Bryan Sutton, Paul Avan, Shyam S Krishnakumar, James E Rothman, Didier Dulon, Saaid Safieddine, Christine Petit
Hearing relies on rapid, temporally precise, and sustained neurotransmitter release at the ribbon synapses of sensory cells, the inner hair cells (IHCs). This process requires otoferlin, a six C2-domain, Ca(2+)-binding transmembrane protein of synaptic vesicles. To decipher the role of otoferlin in the synaptic vesicle cycle, we produced knock-in mice (Otof(Ala515,Ala517/Ala515,Ala517)) with lower Ca(2+)-binding affinity of the C2C domain. The IHC ribbon synapse structure, synaptic Ca(2+) currents, and otoferlin distribution were unaffected in these mutant mice, but auditory brainstem response wave-I amplitude was reduced...
November 7, 2017: ELife
https://www.readbyqxmd.com/read/29026263/effects-of-recreational-noise-on-threshold-and-suprathreshold-measures-of-auditory-function
#5
REVIEW
Angela N C Fulbright, Colleen G Le Prell, Scott K Griffiths, Edward Lobarinas
Noise exposure that causes a temporary threshold shift but no permanent threshold shift can cause degeneration of synaptic ribbons and afferent nerve fibers, with a corresponding reduction in wave I amplitude of the auditory brainstem response (ABR) in animals. This form of underlying damage, hypothesized to also occur in humans, has been termed synaptopathy , and it has been hypothesized that there will be a hidden hearing loss consisting of functional deficits at suprathreshold stimulus levels. This study assessed whether recreational noise exposure history was associated with smaller ABR wave I amplitude and poorer performance on suprathreshold auditory test measures...
November 2017: Seminars in Hearing
https://www.readbyqxmd.com/read/28979188/kiss-and-run-is-a-significant-contributor-to-synaptic-exocytosis-and-endocytosis-in-photoreceptors
#6
Xiangyi Wen, Grant W Saltzgaber, Wallace B Thoreson
Accompanying sustained release in darkness, rod and cone photoreceptors exhibit rapid endocytosis of synaptic vesicles. Membrane capacitance measurements indicated that rapid endocytosis retrieves at least 70% of the exocytotic membrane increase. One mechanism for rapid endocytosis is kiss-and-run fusion where vesicles briefly contact the plasma membrane through a small fusion pore. Release can also occur by full-collapse in which vesicles merge completely with the plasma membrane. We assessed relative contributions of full-collapse and kiss-and-run in salamander photoreceptors using optical techniques to measure endocytosis and exocytosis of large vs...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28949268/maximal-number-of-pre-synaptic-ribbons-are-formed-in-cochlear-region-corresponding-to-middle-frequency-in-mice
#7
Le Yang, DaiShi Chen, TengFei Qu, TongHui Ding, AiHui Yan, Pinggui Gong, Yunyi Liu, Junjun Zhang, ShuSheng Gong, ShiMing Yang, Hong Peng, Ke Liu
OBJECTIVE: To investigate whether there are more quantitative pre-synaptic ribbons formed in the cochlear region corresponding to middle-frequency in cochlea of mice. METHODS: Counts of pre-synaptic ribbons were performed using immunostaining and laser confocal microscopy. Hearing thresholds and function of ribbon synapses were estimated by auditory brain response (ABR) and compound action potential (CAP). Cochlear mapping has been achieved to match the frequencies and corresponding regions along the cochlear spiral...
September 26, 2017: Acta Oto-laryngologica
https://www.readbyqxmd.com/read/28936725/ampa-receptors-at-ribbon-synapses-in-the-mammalian-retina-kinetic-models-and-molecular-identity
#8
Espen Hartveit, Bas-Jan Zandt, Eirik Madsen, Áurea Castilho, Svein Harald Mørkve, Margaret Lin Veruki
In chemical synapses, neurotransmitter molecules released from presynaptic vesicles activate populations of postsynaptic receptors that vary in functional properties depending on their subunit composition. Differential expression and localization of specific receptor subunits are thought to play fundamental roles in signal processing, but our understanding of how that expression is adapted to the signal processing in individual synapses and microcircuits is limited. At ribbon synapses, glutamate release is independent of action potentials and characterized by a high and rapidly changing rate of release...
September 21, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28921532/the-morphological-characterization-of-orientation-biased-displaced-large-field-ganglion-cells-in-the-central-part-of-goldfish-retina
#9
Hideo Hoshi, Fumi Sato
The vertebrate retina has about 30 subtypes of ganglion cells. Each ganglion cell receives synaptic inputs from specific types of bipolar and amacrine cells ramifying at the same depth of the inner plexiform layer (IPL), each of which is thought to process a specific aspect of visual information. Here, we identified one type of displaced ganglion cell in the goldfish retina which had a large and elongated dendritic field. As a population, all of these ganglion cells were oriented in the horizontal axis and perpendicular to the dorsal-ventral axis of the goldfish eye in the central part of retina...
September 18, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28915323/hair-cell-transduction-tuning-and-synaptic-transmission-in-the-mammalian-cochlea
#10
Robert Fettiplace
Sound pressure fluctuations striking the ear are conveyed to the cochlea, where they vibrate the basilar membrane on which sit hair cells, the mechanoreceptors of the inner ear. Recordings of hair cell electrical responses have shown that they transduce sound via submicrometer deflections of their hair bundles, which are arrays of interconnected stereocilia containing the mechanoelectrical transducer (MET) channels. MET channels are activated by tension in extracellular tip links bridging adjacent stereocilia, and they can respond within microseconds to nanometer displacements of the bundle, facilitated by multiple processes of Ca2+-dependent adaptation...
September 12, 2017: Comprehensive Physiology
https://www.readbyqxmd.com/read/28874522/efficient-stimulus-secretion-coupling-at-ribbon-synapses-requires-rim-binding-protein-tethering-of-l-type-ca-2-channels
#11
Fujun Luo, Xinran Liu, Thomas C Südhof, Claudio Acuna
Fast neurotransmitter release from ribbon synapses via Ca(2+)-triggered exocytosis requires tight coupling of L-type Ca(2+) channels to release-ready synaptic vesicles at the presynaptic active zone, which is localized at the base of the ribbon. Here, we used genetic, electrophysiological, and ultrastructural analyses to probe the architecture of ribbon synapses by perturbing the function of RIM-binding proteins (RBPs) as central active-zone scaffolding molecules. We found that genetic deletion of RBP1 and RBP2 did not impair synapse ultrastructure of ribbon-type synapses formed between rod bipolar cells (RBCs) and amacrine type-2 (AII) cells in the mouse retina but dramatically reduced the density of presynaptic Ca(2+) channels, decreased and desynchronized evoked neurotransmitter release, and rendered evoked and spontaneous neurotransmitter release sensitive to the slow Ca(2+) buffer EGTA...
September 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28863864/two-pools-of-vesicles-associated-with-synaptic-ribbons-are-molecularly-prepared-for-release
#12
Proleta Datta, Jared Gilliam, Wallace B Thoreson, Roger Janz, Ruth Heidelberger
Neurons that form ribbon-style synapses are specialized for continuous exocytosis. To this end, their synaptic terminals contain numerous synaptic vesicles, some of which are ribbon associated, that have difference susceptibilities for undergoing Ca(2+)-dependent exocytosis. In this study, we probed the relationship between previously defined vesicle populations and determined their fusion competency with respect to SNARE complex formation. We found that both the rapidly releasing vesicle pool and the releasable vesicle pool of the retinal bipolar cell are situated at the ribbon-style active zones, where they functionally interact...
November 21, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28827351/mechanisms-of-synaptic-depression-at-the-hair-cell-ribbon-synapse-that-support-auditory-nerve-function
#13
Juan D Goutman
Inner hair cells (IHCs) in the cochlea are the mammalian phono-receptors, transducing sound energy into graded changes in membrane potentials, the so called "receptor potentials." Ribbon synapses between IHCs and auditory nerve neurons are responsible for converting receptor potentials into spike rates. The characteristics of auditory nerve responses to sound have been described extensively. For instance, persistent acoustic stimulation produces sensory adaptation, which is revealed as a reduction in neuronal spike rate with time constants in the range of milliseconds to seconds...
September 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28811255/cortical-layers-cyto-myelo-receptor-and-synaptic-architecture-in-human-cortical-areas
#14
REVIEW
Nicola Palomero-Gallagher, Karl Zilles
Cortical layers have classically been identified by their distinctive and prevailing cell types and sizes, as well as the packing densities of cell bodies or myelinated fibers. The densities of multiple receptors for classical neurotransmitters also vary across the depth of the cortical ribbon, and thus determine the neurochemical properties of cyto- and myeloarchitectonic layers. However, a systematic comparison of the correlations between these histologically definable layers and the laminar distribution of transmitter receptors is currently lacking...
August 12, 2017: NeuroImage
https://www.readbyqxmd.com/read/28790889/the-calcineurin-binding-activity-dependent-splice-variant-dynamin1xb-is-highly-enriched-in-synapses-in-various-regions-of-the-central-nervous-system
#15
Marie-Lisa Eich, Ekta Dembla, Silke Wahl, Mayur Dembla, Karin Schwarz, Frank Schmitz
In the present study, we generated and characterized a splice site-specific monoclonal antibody that selectively detects the calcineurin-binding dynamin1 splice variant dynamin1xb. Calcineurin is a Ca(2+)-regulated phosphatase that enhances dynamin1 activity and is an important Ca(2+)-sensing mediator of homeostatic synaptic plasticity in neurons. Using this dynamin1xb-specific antibody, we found dynamin1xb highly enriched in synapses of all analyzed brain regions. In photoreceptor ribbon synapses, dynamin1xb was enriched in close vicinity to the synaptic ribbon in a manner indicative of a peri-active zone immunolabeling...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/28744553/brag2a-a-guanine-nucleotide-exchange-factor-for-arf6-is-a-component-of-the-dystrophin-associated-glycoprotein-complex-at-the-photoreceptor-terminal
#16
Hiroyuki Sakagami, Osamu Katsumata, Yoshinobu Hara, Toshikuni Sasaoka, Masahiro Fukaya
Purpose: Mutations in genes encoding the dystrophin-associated glycoprotein complex (DGC) can cause muscular dystrophy and disturb synaptic transmission in the photoreceptor ribbon synapse. However, the molecular composition and specific functions of the photoreceptor DGC remain unknown. Brefeldin A-resistant Arf-GEF 2 (BRAG2), also known as IQSEC1, is a guanine nucleotide exchange factor for ADP-ribosylation factor 6 (Arf6), a critical GTPase that regulates endosomal trafficking and actin cytoskeleton remodeling...
July 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28744203/synaptic-ribbon-active-zones-in-cone-photoreceptors-operate-independently-from-one-another
#17
Justin J Grassmeyer, Wallace B Thoreson
Cone photoreceptors depolarize in darkness to release glutamate-laden synaptic vesicles. Essential to release is the synaptic ribbon, a structure that helps organize active zones by clustering vesicles near proteins that mediate exocytosis, including voltage-gated Ca(2+) channels. Cone terminals have many ribbon-style active zones at which second-order neurons receive input. We asked whether there are functionally significant differences in local Ca(2+) influx among ribbons in individual cones. We combined confocal Ca(2+) imaging to measure Ca(2+) influx at individual ribbons and patch clamp recordings to record whole-cell ICa in salamander cones...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28743939/a-cryosectioning-technique-for-the-observation-of-intracellular-structures-and-immunocytochemistry-of-tissues-in-atomic-force-microscopy-afm
#18
Eiji Usukura, Akihiro Narita, Akira Yagi, Nobuaki Sakai, Yoshitsugu Uekusa, Yuka Imaoka, Shuichi Ito, Jiro Usukura
The use of cryosectioning facilitates the morphological analysis and immunocytochemistry of cells in tissues in atomic force microscopy (AFM). The cantilever can access all parts of a tissue sample in cryosections after the embedding medium (sucrose) has been replaced with phosphate-buffered saline (PBS), and this approach has enabled the production of a type of high-resolution image. The images resembled those obtained from freeze-etching replica electron microscopy (EM) rather than from thin-section EM. The AFM images showed disks stacked and enveloped by the cell membrane in rod photoreceptor outer segments (ROS) at EM resolution...
July 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28701482/analysis-of-rim-expression-and-function-at-mouse-photoreceptor-ribbon-synapses
#19
Martina Löhner, Norbert Babai, Tanja Müller, Kaspar Gierke, Jenny Atorf, Anneka Joachimsthaler, Angela Peukert, Henrik Martens, Andreas Feigenspan, Jan Kremers, Susanne Schoch, Johann Helmut Brandstätter, Hanna Regus-Leidig
RAB3A-interacting molecule (RIM) proteins are important regulators of transmitter release from active zones. At conventional chemical synapses, RIMs contribute substantially to vesicle priming and docking and their loss reduces the readily releasable pool of synaptic vesicles by up to 75%. The priming function of RIMs is mediated via the formation of a tripartite complex with Munc13 and RAB3A, which brings synaptic vesicles in close proximity to Ca(2+) channels and the fusion site and activates Munc13. We reported previously that, at mouse photoreceptor ribbon synapses, vesicle priming is Munc13 independent...
August 16, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28641988/wavy-multistratified-amacrine-cells-in-the-monkey-retina-contain-immunoreactive-secretoneurin
#20
Andrea S Bordt, Ye Long, Nobuo Kouyama, Elizabeth S Yamada, Jens Hannibal, David W Marshak
The goals of this study were to describe the morphology, neurotransmitter content and synaptic connections of neurons in primate retinas that contain the neuropeptide secretoneurin. Amacrine cells were labeled with antibodies to secretoneurin in macaque and baboon retinas. Their processes formed three distinct plexuses in the inner plexiform layer: one in the outermost stratum, one in the center and one in the innermost stratum. In light microscopic double immunolabeling experiments, GABA was colocalized with secretoneurin in these cells, but glycine transporter 1 and Substance P were not...
August 2017: Peptides
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