The Experts below are selected from a list of 101016 Experts worldwide ranked by ideXlab platform
Pascal S Kaeser - One of the best experts on this subject based on the ideXlab platform.
-
pkc phosphorylation of liprin α3 triggers phase separation and controls presynaptic Active Zone structure
Nature Communications, 2021Co-Authors: Javier Emperadormelero, Hajnalka Nyitrai, Man Yan Wong, Shanshan Wang, Giovanni De Nola, Tom Kirchhausen, Pascal S KaeserAbstract:The Active Zone of a presynaptic nerve terminal defines sites for neurotransmitter release. Its protein machinery may be organized through liquid-liquid phase separation, a mechanism for the formation of membrane-less subcellular compartments. Here, we show that the Active Zone protein Liprin-α3 rapidly and reversibly undergoes phase separation in transfected HEK293T cells. Condensate formation is triggered by Liprin-α3 PKC-phosphorylation at serine-760, and RIM and Munc13 are co-recruited into membrane-attached condensates. Phospho-specific antibodies establish phosphorylation of Liprin-α3 serine-760 in transfected cells and mouse brain tissue. In primary hippocampal neurons of newly generated Liprin-α2/α3 double knockout mice, synaptic levels of RIM and Munc13 are reduced and the pool of releasable vesicles is decreased. Re-expression of Liprin-α3 restored these presynaptic defects, while mutating the Liprin-α3 phosphorylation site to abolish phase condensation prevented this rescue. Finally, PKC activation in these neurons acutely increased RIM, Munc13 and neurotransmitter release, which depended on the presence of phosphorylatable Liprin-α3. Our findings indicate that PKC-mediated phosphorylation of Liprin-α3 triggers its phase separation and modulates Active Zone structure and function.
-
phosphorylation triggers presynaptic phase separation of liprin α3 to control Active Zone structure
bioRxiv, 2020Co-Authors: Javier Emperadormelero, Man Yan Wong, Shanshan Wang, Giovanni De Nola, Tom Kirchhausen, Pascal S KaeserAbstract:Liquid-liquid phase separation enables the assembly of membrane-less subcellular compartments, but testing its biological functions has been difficult. The presynaptic Active Zone, protein machinery in nerve terminals that defines sites for neurotransmitter release, may be organized through phase separation. Here, we discover that the Active Zone protein Liprin-α3 rapidly and reversibly undergoes phase separation upon phosphorylation by PKC at a single site. RIM and Munc13 are co-recruited to membrane-attached condensates, and phospho-specific antibodies establish Liprin-α3 phosphorylation in vivo. At synapses of newly generated Liprin-α2/α3 double knockout mice, RIM, Munc13 and the pool of releasable vesicles were reduced. Re-expression of Liprin-α3 restored these defects, but mutating the Liprin-α3 phosphorylation site to abolish phase condensation prevented rescue. Finally, PKC activation acutely increased RIM, Munc13 and neurotransmitter release, which depended on the presence of phosphorylatable Liprin-α3. We conclude that Liprin-α3 phosphorylation rapidly triggers presynaptic phase separation to modulate Active Zone structure and function.
-
assembly of the presynaptic Active Zone
Current Opinion in Neurobiology, 2020Co-Authors: Javier Emperadormelero, Pascal S KaeserAbstract:In a presynaptic nerve terminal, the Active Zone is composed of sophisticated protein machinery that enables secretion on a submillisecond time scale and precisely targets it toward postsynaptic receptors. The past two decades have provided deep insight into the roles of Active Zone proteins in exocytosis, but we are only beginning to understand how a neuron assembles Active Zone protein complexes into effective molecular machines. In this review, we outline the fundamental processes that are necessary for Active Zone assembly and discuss recent advances in understanding assembly mechanisms that arise from genetic, morphological and biochemical studies. We further outline the challenges ahead for understanding this important problem.
-
rim c2b domains target presynaptic Active Zone functions to pip2 containing membranes
Neuron, 2018Co-Authors: Arthur P H De Jong, Man Yan Wong, Carlos M Roggero, Chad A Brautigam, Josep Rizo, Pascal S KaeserAbstract:Rapid and efficient synaptic vesicle fusion requires a pool of primed vesicles, the nearby tethering of Ca2+ channels, and the presence of the phospholipid PIP2 in the target membrane. Although the presynaptic Active Zone mediates the first two requirements, it is unclear how fusion is targeted to membranes with high PIP2 content. Here we find that the C2B domain of the Active Zone scaffold RIM is critical for action potential-triggered fusion. Remarkably, the known RIM functions in vesicle priming and Ca2+ influx do not require RIM C2B domains. Instead, biophysical experiments reveal that RIM C2 domains, which lack Ca2+ binding, specifically bind to PIP2. Mutational analyses establish that PIP2 binding to RIM C2B and its tethering to the other RIM domains are crucial for efficient exocytosis. We propose that RIM C2B domains are constitutive PIP2-binding modules that couple mechanisms for vesicle priming and Ca2+ channel tethering to PIP2-containing target membranes.
-
liprin α3 controls vesicle docking and exocytosis at the Active Zone of hippocampal synapses
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Man Yan Wong, Changliang Liu, Shan Shan H Wang, Aram C F Roquas, Stephen C Fowler, Pascal S KaeserAbstract:The presynaptic Active Zone provides sites for vesicle docking and release at central nervous synapses and is essential for speed and accuracy of synaptic transmission. Liprin-α binds to several Active Zone proteins, and loss-of-function studies in invertebrates established important roles for Liprin-α in neurodevelopment and Active Zone assembly. However, Liprin-α localization and functions in vertebrates have remained unclear. We used stimulated emission depletion superresolution microscopy to systematically determine the localization of Liprin-α2 and Liprin-α3, the two predominant Liprin-α proteins in the vertebrate brain, relative to other Active-Zone proteins. Both proteins were widely distributed in hippocampal nerve terminals, and Liprin-α3, but not Liprin-α2, had a prominent component that colocalized with the Active-Zone proteins Bassoon, RIM, Munc13, RIM-BP, and ELKS. To assess Liprin-α3 functions, we generated Liprin-α3–KO mice by using CRISPR/Cas9 gene editing. We found reduced synaptic vesicle tethering and docking in hippocampal neurons of Liprin-α3–KO mice, and synaptic vesicle exocytosis was impaired. Liprin-α3 KO also led to mild alterations in Active Zone structure, accompanied by translocation of Liprin-α2 to Active Zones. These findings establish important roles for Liprin-α3 in Active-Zone assembly and function, and suggest that interplay between various Liprin-α proteins controls their Active-Zone localization.
Toshihisa Ohtsuka - One of the best experts on this subject based on the ideXlab platform.
-
double deletion of the Active Zone proteins cast elks in the mouse forebrain causes high mortality of newborn pups
Molecular Brain, 2020Co-Authors: Akari Hagiwara, Yamato Hida, Shun Hamada, Toshihisa OhtsukaAbstract:Presynaptic Active Zone cytomatrix proteins are essential elements of neurotransmitter release machinery that govern neural transmission. Among Active Zone proteins, cytomatrix at the Active Zone-associated structural protein (CAST) is known to regulate Active Zone size in retinal photoreceptors and neurotransmitter release by recruiting Ca(2+) channels at various synapses. However, the role of ELKS-a protein from the same family as CAST-and the synergistic roles of CAST/ELKS have not been thoroughly investigated, particularly with regard to mouse behavior. Here, we generated ELKS conditional KO in mouse forebrain synapses by crossing ELKS flox mice with a CaMKII promoter-induced Cre line. Results showed that CAST is dominant at these synapses and that ELKS can support CAST function, but is less effective in the ELKS single KO. Pups of CAST/ELKS double KO in the forebrain were born in Mendelian rations but resulted in eventual death right after the birth. Anatomically, the forebrain neuronal compositions of CAST KO and CAST/ELKS double KO mice were indistinguishable, and the sensory neural network from whiskers on the face was identified as barrelette-like patches in the spinal trigeminal nucleus. Therefore, depletion of CAST and ELKS disrupts neurotransmission from sensory to motor networks, which can lead to deficits in exploration and failure to suckle.
-
role of the Active Zone protein elks in insulin secretion from pancreatic β cells
Molecular metabolism, 2019Co-Authors: Mica Oharaimaizumi, Kyota Aoyagi, Toshihisa OhtsukaAbstract:Abstract Background Insulin is stored within large dense-core granules in pancreatic beta (β)-cells and is released by Ca2+-triggered exocytosis with increasing blood glucose levels. Polarized and targeted secretion of insulin from β-cells in pancreatic islets into the vasculature has been proposed; however, the mechanisms related to cellular and molecular localization remain largely unknown. Within nerve terminals, the Ca2+-dependent release of a polarized transmitter is limited to the Active Zone, a highly specialized area of the presynaptic membrane. Several Active Zone-specific proteins have been characterized; among them, the CAST/ELKS protein family members have the ability to form large protein complexes with other Active Zone proteins to control the structure and function of the Active Zone for tight regulation of neurotransmitter release. Notably, ELKS but not CAST is also expressed in β-cells, implying that ELKS may be involved in polarized insulin secretion from β-cells. Scope of review This review provides an overview of the current findings regarding the role(s) of ELKS and other Active Zone proteins in β-cells and focuses on the molecular mechanism underlying ELKS regulation within polarized insulin secretion from islets. Major conclusions ELKS localizes at the vascular-facing plasma membrane of β-cells in mouse pancreatic islets. ELKS forms a potent insulin secretion complex with L-type voltage-dependent Ca2+ channels on the vascular-facing plasma membrane of β-cells, enabling polarized Ca2+ influx and first-phase insulin secretion from islets. This model provides novel insights into the functional polarity observed during insulin secretion from β-cells within islets at the molecular level. This Active Zone-like region formed by ELKS at the vascular side of the plasma membrane is essential for coordinating physiological insulin secretion and may be disrupted in diabetes.
-
sad b phosphorylation of cast controls Active Zone vesicle recycling for synaptic depression
Cell Reports, 2016Co-Authors: Sumiko Mochida, Akari Hagiwara, Yamato Hida, Shun Hamada, Isao Kitajima, Shota Tanifuji, Manabu Abe, Misato Yasumura, Kenji Sakimura, Toshihisa OhtsukaAbstract:Short-term synaptic depression (STD) is a common form of activity-dependent plasticity observed widely in the nervous system. Few molecular pathways that control STD have been described, but the Active Zone (AZ) release apparatus provides a possible link between neuronal activity and plasticity. Here, we show that an AZ cytomatrix protein CAST and an AZ-associated protein kinase SAD-B coordinately regulate STD by controlling reloading of the AZ with release-ready synaptic vesicles. SAD-B phosphorylates the N-terminal serine (S45) of CAST, and S45 phosphorylation increases with higher firing rate. A phosphomimetic CAST (S45D) mimics CAST deletion, which enhances STD by delaying reloading of the readily releasable pool (RRP), resulting in a pool size decrease. A phosphonegative CAST (S45A) inhibits STD and accelerates RRP reloading. Our results suggest that the CAST/SAD-B reaction serves as a brake on synaptic transmission by temporal calibration of activity and synaptic depression via RRP size regulation.
-
involvement of elks an Active Zone protein in exocytotic release from rbl 2h3 cells
Cellular Immunology, 2009Co-Authors: Hidehiro Nomura, Toshihisa Ohtsuka, Masahiko Tanaka, Satoshi Tadokoro, Naohide HirashimaAbstract:Recent studies have indicated that SNARE proteins and their accessory proteins are involved in exocytotic release in mast cells and neurotransmitter release in neuronal cells. These data suggest that a similar molecular mechanism operates in both systems. However, mast and neuronal cells are structurally very different; an Active Zone is found in neuronal cells. In the present study, we examined the involvement of Active Zone proteins during exocytosis in mast cells. We found that several Active Zone proteins are expressed in RBL-2H3 cells and focused on one of those proteins called ELKS. Overexpression and knockdown of ELKS caused an increase and decrease in exocytotic activity, respectively. Immunocytochemical analysis and live imaging of the expression of YFP-conjugated ELKS showed that ELKS was translocated to the plasma membrane after antigen stimulation. These results suggest that ELKS positively regulates exocytotic release in RBL-2H3 by acting on the plasma membrane upon stimulation.
-
localization of the Active Zone proteins cast elks and piccolo at neuromuscular junctions
Neuroreport, 2007Co-Authors: Takashi Tokoro, Susumu Higa, Maki Deguchitawarada, Isao Kitajima, Eiji Inoue, Toshihisa OhtsukaAbstract:CAST and ELKS are major components of the presynaptic Active Zones of neurons in the central nervous system, but it remains elusive whether CAST and ELKS are also components of synapses in the peripheral nervous system. Here, we have attempted to examine their expression and localization at the synapses of neuromuscular junctions. Immunoreactivity for ELKS is partly colocalized with that for the major neuromuscular junctions marker α-bungarotoxin, which binds to acetylcholine receptors. Moreover, another Active Zone protein, Piccolo, is also present at neuromuscular junctions, together with ELKS, whereas CAST is not found. These results suggest that at least ELKS and Piccolo, but not CAST, are components of neuromuscular junction synapses in the peripheral nervous system.
Thomas C Sudhof - One of the best experts on this subject based on the ideXlab platform.
-
a trio of Active Zone proteins comprised of rim bps rims and munc13s governs neurotransmitter release
Cell Reports, 2020Co-Authors: Marisa M Brockmann, Thomas C Sudhof, Fereshteh Zarebidaki, Marcial Camacho, Katharina M Grauel, Thorsten Trimbuch, Christian RosenmundAbstract:Summary At the presynaptic Active Zone, action-potential-triggered neurotransmitter release requires that fusion-competent synaptic vesicles are placed next to Ca2+ channels. The Active Zone resident proteins RIM, RBP, and Munc13 are essential contributors for vesicle priming and Ca2+-channel recruitment. Although the individual contributions of these scaffolds have been extensively studied, their respective functions in neurotransmission are still incompletely understood. Here, we analyze the functional interactions of RIMs, RBPs, and Munc13s at the genetic, molecular, functional, and ultrastructural levels in a mammalian synapse. We find that RBP, together with Munc13, promotes vesicle priming at the expense of RBP’s role in recruiting presynaptic Ca2+ channels, suggesting that the support of RBP for vesicle priming and Ca2+-secretion coupling is mutually exclusive. Our results demonstrate that the functional interaction of RIM, RBP, and Munc13 is more profound than previously envisioned, acting as a functional trio that govern basic and short-term plasticity properties of neurotransmission.
-
how to make an Active Zone unexpected universal functional redundancy between rims and rim bps
Neuron, 2016Co-Authors: Claudio Acuna, Thomas C SudhofAbstract:Summary RIMs and RIM-binding proteins (RBPs) are evolutionary conserved multidomain proteins of presynaptic Active Zones that are known to recruit Ca 2+ channels; in addition, RIMs perform well-recognized functions in tethering and priming synaptic vesicles for exocytosis. However, deletions of RIMs or RBPs in mice cause only partial impairments in various Active Zone functions and have no effect on Active Zone structure, as visualized by electron micrographs, suggesting that their contribution to Active Zone functions is limited. Here, we show in synapses of the calyx of Held in vivo and hippocampal neurons in culture that combined, but not individual, deletions of RIMs and RBPs eliminate tethering and priming of synaptic vesicles, deplete presynaptic Ca 2+ channels, and ablate Active Zone complexes, as analyzed by electron microscopy of chemically fixed synapses. Thus, RBPs perform unexpectedly broad roles at the Active Zone that together with those of RIMs are essential for all Active Zone functions.
-
the presynaptic Active Zone
Neuron, 2012Co-Authors: Thomas C SudhofAbstract:Neurotransmitters are released by synaptic vesicle exocytosis at the Active Zone of a presynaptic nerve terminal. In this review, I discuss the molecular composition and function of the Active Zone. Active Zones are composed of an evolutionarily conserved protein complex containing as core constituents RIM, Munc13, RIM-BP, α-liprin, and ELKS proteins. This complex docks and primes synaptic vesicles for exocytosis, recruits Ca 2+ channels to the site of exocytosis, and positions the Active Zone exactly opposite to postsynaptic specializations via transsynaptic cell-adhesion molecules. Moreover, this complex mediates short- and long-term plasticity in response to bursts of action potentials, thus critically contributing to the computational power of a synapse.
-
rim determines ca2 channel density and vesicle docking at the presynaptic Active Zone
Neuron, 2011Co-Authors: Yunyun Han, Pascal S Kaeser, Thomas C Sudhof, Ralf SchneggenburgerAbstract:At presynaptic Active Zones, neurotransmitter release is initiated by the opening of voltage-gated Ca²+ channels close to docked vesicles. The mechanisms that enrich Ca²+ channels at Active Zones are, however, largely unknown, possibly because of the limited presynaptic accessibility of most synapses. Here, we have established a Cre-lox based conditional knockout approach at a presynaptically accessible central nervous system synapse, the calyx of Held, to directly study the functions of RIM proteins. Removal of all RIM1/2 isoforms strongly reduced the presynaptic Ca²+ channel density, revealing a role of RIM proteins in Ca²+ channel targeting. Removal of RIMs also reduced the readily releasable pool, paralleled by a similar reduction of the number of docked vesicles, and the Ca²+ channel-vesicle coupling was decreased. Thus, RIM proteins co-ordinately regulate key functions for fast transmitter release, enabling a high presynaptic Ca²+ channel density and vesicle docking at the Active Zone.
-
multiple roles for the Active Zone protein rim1α in late stages of neurotransmitter release
Neuron, 2004Co-Authors: Nicole Calakos, Susanne Schoch, Thomas C Sudhof, Robert C MalenkaAbstract:Abstract The Active Zone protein RIM1α interacts with multiple Active Zone and synaptic vesicle proteins and is implicated in short- and long-term synaptic plasticity, but it is unclear how RIM1α's biochemical interactions translate into physiological functions. To address this question, we analyzed synaptic transmission in autaptic neurons cultured from RIM1α −/− mice. Deletion of RIM1α causes a large reduction in the readily releasable pool of vesicles, alters short-term plasticity, and changes the properties of evoked asynchronous release. Lack of RIM1α, however, had no effect on synapse formation, spontaneous release, overall Ca 2+ sensitivity of release, or synaptic vesicle recycling. These results suggest that RIM1α modulates sequential steps in synaptic vesicle exocytosis through serial protein-protein interactions and that this modulation is the basis for RIM1α's role in synaptic plasticity.
Eckart D Gundelfinger - One of the best experts on this subject based on the ideXlab platform.
-
Role of Bassoon and Piccolo in Assembly and Molecular Organization of the Active Zone
Frontiers in Synaptic Neuroscience, 2016Co-Authors: Eckart D Gundelfinger, Carsten Reissner, Craig C GarnerAbstract:Bassoon and Piccolo are two very large scaffolding proteins of the cytomatrix assembled at the Active Zone (CAZ) where neurotransmitter is released. They share regions of high sequence similarity distributed along their entire length and seem to share both overlapping and distinct functions in organizing the CAZ. Here, we survey our present knowledge on protein-protein interactions and recent progress in understanding of molecular functions of these two giant proteins. These include roles in the assembly of Active Zones, the localization of voltage-gated Ca2+ channels in the vicinity of release sites, synaptic vesicle priming and, in the case of Piccolo, a role in the dynamic assembly of the actin cytoskeleton. Piccolo and Bassoon are also important for the maintenance of presynaptic structure and function, as well as for the assembly of CAZ specializations such as synaptic ribbons. Recent findings suggest that they are also involved in the regulation activity-dependent communication between presynaptic boutons and the neuronal nucleus. Together these observations suggest that Bassoon and Piccolo use their modular structure to organize super-molecular complexes essential for various aspects of presynaptic function.
-
Trio, a rho family GEF, interacts with the presynaptic Active Zone proteins piccolo and bassoon
PLoS ONE, 2016Co-Authors: Ryan T. Terry-lorenzo, Clarissa L Waites, Viviana I. Torres, Dhananjay Wagh, Jose Galaz, Selene K Swanson, Eckart D Gundelfinger, Laurence Florens, Michael P Washburn, Richard J. ReimerAbstract:Synaptic vesicles (SVs) fuse with the plasma membrane at a precise location called the presynaptic Active Zone (AZ). This fusion is coordinated by proteins embedded within a cytoskeletal matrix assembled at the AZ (CAZ). In the present study, we have identified a novel binding partner for the CAZ proteins Piccolo and Bassoon. This interacting protein, Trio, is a member of the Dbl family of guanine nucleotide exchange factors (GEFs) known to regulate the dynamic assembly of actin and growth factor dependent axon guidance and synaptic growth. Trio was found to interact with the C-terminal PBH 9/10 domains of Piccolo and Bassoon via its own N-terminal Spectrin repeats, a domain that is also critical for its localization to the CAZ. Moreover, our data suggest that regions within the C-terminus of Trio negatively regulate its interactions with Piccolo/Bassoon. These findings provide a mechanism for the presynaptic targeting of Trio and support a model in which Piccolo and Bassoon play a role in regulating neurotransmission through interactions with proteins, including Trio, that modulate the dynamic assembly of F-actin during cycles of synaptic vesicle exo- and endocytosis.
-
molecular organization and plasticity of the cytomatrix at the Active Zone
Current Opinion in Neurobiology, 2012Co-Authors: Eckart D Gundelfinger, Anna FejtovaAbstract:Regulated neurotransmitter release from presynaptic boutons is crucial for the functioning of chemical synapses, what in turn governs the functional performance of the nervous system. Release occurs at the Active Zone (AZ), a specialized region of the presynaptic plasma membrane that is defined by a unique and complex meshwork of proteins--the cytomatrix at the AZ (CAZ). Important functions of CAZ proteins include recruitment, docking and priming of synaptic vesicles as well as appropriate localization of voltage-gated calcium channels near vesicle docking sites. We will discuss recent progress in the understanding of the topological localization and the molecular functions of characteristic CAZ proteins as well as emerging molecular mechanisms underlying presynaptic plasticity that involve significant structural CAZ remodeling.
-
Formation of Golgi-Derived Active Zone Precursor Vesicles
Journal of Neuroscience, 2012Co-Authors: C. Maas, Sergio Leal-ortiz, Anna Fejtova, Wilko D Altrock, N. E. Ziv, Viviana I. Torres, Dhananjay Wagh, Ryan T. Terry-lorenzo, Eckart D Gundelfinger, Craig C GarnerAbstract:Vesicular trafficking of presynaptic and postsynaptic components is emerging as a general cellular mechanism for the delivery of scaffold proteins, ion channels, and receptors to nascent and mature synapses. However, the molecular mechanisms leading to the selection of cargos and their differential transport to subneuronal compartments are not well understood, in part because of the mixing of cargos at the plasma membrane and/or within endosomal compartments. In the present study, we have explored the cellular mechanisms of Active Zone precursor vesicle assembly at the Golgi in dissociated hippocampal neurons of Rattus norvegicus. Our studies show that Piccolo, Bassoon, and ELKS2/CAST exit the trans-Golgi network on a common vesicle that requires Piccolo and Bassoon for its proper assembly. In contrast, Munc13 and synaptic vesicle proteins use distinct sets of Golgi-derived transport vesicles, while RIM1α associates with vesicular membranes in a post-Golgi compartment. Furthermore, Piccolo and Bassoon are necessary for ELKS2/CAST to leave the Golgi in association with vesicles, and a core domain of Bassoon is sufficient to facilitate formation of these vesicles. While these findings support emerging principles regarding Active Zone differentiation, the cellular and molecular analyses reported here also indicate that the Piccolo-Bassoon transport vesicles leaving the Golgi may undergo further changes in protein composition before arriving at synaptic sites.
-
Molecular organization of the presynaptic Active Zone
Cell and Tissue Research, 2006Co-Authors: Susanne Schoch, Eckart D GundelfingerAbstract:The exocytosis of neurotransmitter-filled synaptic vesicles is under tight temporal and spatial control in presynaptic nerve terminals. The fusion of synaptic vesicles is restricted to a specialized area of the presynaptic plasma membrane: the Active Zone. The protein network that constitutes the cytomatrix at the Active Zone (CAZ) is involved in the organization of docking and priming of synaptic vesicles and in mediating use-dependent changes in release during short-term and long-term synaptic plasticity. To date, five protein families whose members are highly enriched at Active Zones (Munc13s, RIMs, ELKS proteins, Piccolo and Bassoon, and the liprins-α), have been characterized. These multidomain proteins are instrumental for the diverse functions performed by the presynaptic Active Zone.
Michael L Nonet - One of the best experts on this subject based on the ideXlab platform.
-
syd 2 liprin α organizes presynaptic Active Zone formation through elks
Nature Neuroscience, 2006Co-Authors: Hidenori Taru, Scott L Deken, Brock Grill, Brian D. Ackley, Michael L NonetAbstract:A central event in synapse development is formation of the presynaptic Active Zone in response to positional cues. Three Active Zone proteins, RIM, ELKS (also known as ERC or CAST) and Liprin-α, bind each other and are implicated in linking Active Zone formation to synaptic vesicle release. Loss of function in Caenorhabditis eleganssyd-2 Liprin-α alters the size of presynaptic specializations and disrupts synaptic vesicle accumulation. Here we report that a missense mutation in the coiled-coil domain of SYD-2 causes a gain of function. In HSN synapses, the syd-2(gf) mutation promotes synapse formation in the absence of syd-1, which is essential for HSN synapse formation. syd-2(gf) also partially suppresses the synaptogenesis defects in syg-1 and syg-2 mutants. The activity of syd-2(gf) requires elks-1, an ELKS homolog; but not unc-10, a RIM homolog. The mutant SYD-2 shows increased association with ELKS. These results establish a functional dependency for assembly of the presynaptic Active Zone in which SYD-2 plays a key role.
-
syd 2 liprin alpha organizes presynaptic Active Zone formation through elks
Nature Neuroscience, 2006Co-Authors: Ya Dai, Scott L Deken, Michael L Nonet, Hidenori Taru, Brock Grill, Brian D. Ackley, Yishi JinAbstract:A central event in synapse development is formation of the presynaptic Active Zone in response to positional cues. Three Active Zone proteins, RIM, ELKS (also known as ERC or CAST) and Liprin-alpha, bind each other and are implicated in linking Active Zone formation to synaptic vesicle release. Loss of function in Caenorhabditis elegans syd-2 Liprin-alpha alters the size of presynaptic specializations and disrupts synaptic vesicle accumulation. Here we report that a missense mutation in the coiled-coil domain of SYD-2 causes a gain of function. In HSN synapses, the syd-2(gf) mutation promotes synapse formation in the absence of syd-1, which is essential for HSN synapse formation. syd-2(gf) also partially suppresses the synaptogenesis defects in syg-1 and syg-2 mutants. The activity of syd-2(gf) requires elks-1, an ELKS homolog; but not unc-10, a RIM homolog. The mutant SYD-2 shows increased association with ELKS. These results establish a functional dependency for assembly of the presynaptic Active Zone in which SYD-2 plays a key role.
-
a post docking role for Active Zone protein rim
Nature Neuroscience, 2001Co-Authors: Sandhya P Koushika, Janet E Richmond, Gayla Hadwiger, Robby M Weimer, Erik M Jorgensen, Michael L NonetAbstract:Rim1 was previously identified as a Rab3 effector localized to the presynaptic Active Zone in vertebrates. Here we demonstrate that C. elegans unc-10 mutants lacking Rim are viable, but exhibit behavioral and physiological defects that are more severe than those of Rab3 mutants. Rim is localized to synaptic sites in C. elegans, but the ultrastructure of the presynaptic densities is normal in Rim mutants. Moreover, normal levels of docked synaptic vesicles were observed in mutants, suggesting that Rim is not involved in the docking process. The level of fusion competent vesicles at release sites was reduced fivefold in Rim mutants, but calcium sensitivity of release events was unchanged. Furthermore, expression of a constitutively open form of syntaxin suppressed the physiological defects of Rim mutants, suggesting Rim normally acts to regulate conformational changes in syntaxin. These data suggest Rim acts after vesicle docking likely via regulating priming.
