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Cesare Montecucco - One of the best experts on this subject based on the ideXlab platform.
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calpains participate in nerve terminal degeneration induced by spider and snake Presynaptic neurotoxins
Toxicon, 2013Co-Authors: Elisa Duregotti, Cesare Montecucco, Erik Tedesco, Michela RigoniAbstract:Abstract α-latrotoxin and snake Presynaptic phospholipases A2 neurotoxins target the Presynaptic Membrane of axon terminals of the neuromuscular junction causing paralysis. These neurotoxins display different biochemical activities, but similarly alter the Presynaptic Membrane permeability causing Ca 2+ overload within the nerve terminals, which in turn induces nerve degeneration. Using different methods, here we show that the calcium-activated proteases calpains are involved in the cytoskeletal rearrangements that we have previously documented in neurons exposed to α-latrotoxin or to snake Presynaptic phospholipases A2 neurotoxins. These results indicate that calpains, activated by the massive calcium influx from the extracellular medium, target fundamental components of neuronal cytoskeleton such as spectrin and neurofilaments, whose cleavage is functional to the ensuing nerve terminal fragmentation.
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Presynaptic receptor arrays for clostridial neurotoxins
Trends in Microbiology, 2004Co-Authors: Cesare Montecucco, Ornella Rossetto, Giampietro SchiavoAbstract:Tetanus and botulinum neurotoxins act at femtomolar concentrations and are specific for the Presynaptic Membrane of neurons. Their mode of binding is still poorly defined. The exceptional potency and specificity of these neurotoxins raise unprecedented questions about the nature of their receptor(s) and the mode of their Membrane binding. We propose a Presynaptic binding process for tetanus and botulinum neurotoxins based on a capture step performed by an antenna, consisting of a lipid- or a protein-linked oligosaccharide, which brings about a very large Membrane concentration effect; this is followed by additional interactions with arrays of receptor molecules, arranged in Membrane microdomains, which render the neurotoxin binding practically irreversible and triggers endocytosis.
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phosphorylation of vamp synaptobrevin in synaptic vesicles by endogenous protein kinases
Journal of Neurochemistry, 2002Co-Authors: H B Nielander, Cesare Montecucco, Giampietro Schiavo, Flavia Valtorta, Franco Onofri, Paul Greengard, Fabio BenfenatiAbstract:VAMP/synaptobrevin (SYB), an integral Membrane protein of small synaptic vesicles, is specifically cleaved by tetanus neurotoxin and botulinum neurotoxins B, D, F, and G and is thought to play an important role in the docking and/or fusion of synaptic vesicles with the Presynaptic Membrane. Potential phosphorylation sites for various kinases are present in SYB sequence. We have studied whether SYB is a substrate for protein kinases that are present in nerve terminals and known to modulate neurotransmitter release. SYB can be phosphorylated within the same vesicle by endogenous Ca 2+ /calmodulin-dependent protein kinase II (CaMKII) associated with synaptic vesicles. This phosphorylation reaction occurs rapidly and involves serine and threonine residues in the cytoplasmic region of SYB. Similarly to CaMKII, a casein kinase II (CasKII) activity copurifying with synaptic vesicles is able to phosphorylate SYB selectively on serine residues of the cytoplasmic region. This phosphorylation reaction is markedly stimulated by sphingosine, a sphingolipid known to activate CasKII and to inhibit CaM-KII and protein kinase C. The results show that SYB is a potential substrate for protein kinases involved in the regulation of neurotransmitter release and open the possibility that phosphorylation of SYB plays a role in modulating the molecular interactions between synaptic vesicles and the Presynaptic Membrane.
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tetanus and botulinum neurotoxins turning bad guys into good by research
Toxicon, 2001Co-Authors: Ornella Rossetto, M Seveso, Paola Caccin, Giampietro Schiavo, Cesare MontecuccoAbstract:Abstract The neuroparalytic syndromes of tetanus and botulism are caused by neurotoxins produced by bacteria of the genus Clostridium . They are 150 kDa proteins consisting of three-domains, endowed with different functions: neurospecific binding, Membrane translocation and specific proteolysis of three key components of the neuroexocytosis apparatus. After binding to the Presynaptic Membrane of motoneurons, tetanus neurotoxin (TeNT) is internalized and transported retroaxonally to the spinal cord, where it blocks neurotransmitter release from spinal inhibitory interneurons. In contrast, the seven botulinum neurotoxins (BoNT) act at the periphery and inhibit acetylcholine release from peripheral cholinergic nerve terminals. TeNT and BoNT-B, -D, -F and -G cleave specifically at single but different peptide bonds, VAMP/synaptobrevin, a Membrane protein of small synaptic vesicles. BoNT types -A, -C and -E cleave SNAP-25 at different sites within the COOH-terminus, whereas BoNT-C also cleaves syntaxin. BoNTs are increasingly used in medicine for the treatment of human diseases characterized by hyperfunction of cholinergic terminals.
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tetanus and botulinum neurotoxins turning bad guys into good by research
Toxicon, 2001Co-Authors: Ornella Rossetto, M Seveso, Paola Caccin, Giampietro Schiavo, Cesare MontecuccoAbstract:Abstract The neuroparalytic syndromes of tetanus and botulism are caused by neurotoxins produced by bacteria of the genus Clostridium . They are 150 kDa proteins consisting of three-domains, endowed with different functions: neurospecific binding, Membrane translocation and specific proteolysis of three key components of the neuroexocytosis apparatus. After binding to the Presynaptic Membrane of motoneurons, tetanus neurotoxin (TeNT) is internalized and transported retroaxonally to the spinal cord, where it blocks neurotransmitter release from spinal inhibitory interneurons. In contrast, the seven botulinum neurotoxins (BoNT) act at the periphery and inhibit acetylcholine release from peripheral cholinergic nerve terminals. TeNT and BoNT-B, -D, -F and -G cleave specifically at single but different peptide bonds, VAMP/synaptobrevin, a Membrane protein of small synaptic vesicles. BoNT types -A, -C and -E cleave SNAP-25 at different sites within the COOH-terminus, whereas BoNT-C also cleaves syntaxin. BoNTs are increasingly used in medicine for the treatment of human diseases characterized by hyperfunction of cholinergic terminals.
Giampietro Schiavo - One of the best experts on this subject based on the ideXlab platform.
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Presynaptic receptor arrays for clostridial neurotoxins
Trends in Microbiology, 2004Co-Authors: Cesare Montecucco, Ornella Rossetto, Giampietro SchiavoAbstract:Tetanus and botulinum neurotoxins act at femtomolar concentrations and are specific for the Presynaptic Membrane of neurons. Their mode of binding is still poorly defined. The exceptional potency and specificity of these neurotoxins raise unprecedented questions about the nature of their receptor(s) and the mode of their Membrane binding. We propose a Presynaptic binding process for tetanus and botulinum neurotoxins based on a capture step performed by an antenna, consisting of a lipid- or a protein-linked oligosaccharide, which brings about a very large Membrane concentration effect; this is followed by additional interactions with arrays of receptor molecules, arranged in Membrane microdomains, which render the neurotoxin binding practically irreversible and triggers endocytosis.
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phosphorylation of vamp synaptobrevin in synaptic vesicles by endogenous protein kinases
Journal of Neurochemistry, 2002Co-Authors: H B Nielander, Cesare Montecucco, Giampietro Schiavo, Flavia Valtorta, Franco Onofri, Paul Greengard, Fabio BenfenatiAbstract:VAMP/synaptobrevin (SYB), an integral Membrane protein of small synaptic vesicles, is specifically cleaved by tetanus neurotoxin and botulinum neurotoxins B, D, F, and G and is thought to play an important role in the docking and/or fusion of synaptic vesicles with the Presynaptic Membrane. Potential phosphorylation sites for various kinases are present in SYB sequence. We have studied whether SYB is a substrate for protein kinases that are present in nerve terminals and known to modulate neurotransmitter release. SYB can be phosphorylated within the same vesicle by endogenous Ca 2+ /calmodulin-dependent protein kinase II (CaMKII) associated with synaptic vesicles. This phosphorylation reaction occurs rapidly and involves serine and threonine residues in the cytoplasmic region of SYB. Similarly to CaMKII, a casein kinase II (CasKII) activity copurifying with synaptic vesicles is able to phosphorylate SYB selectively on serine residues of the cytoplasmic region. This phosphorylation reaction is markedly stimulated by sphingosine, a sphingolipid known to activate CasKII and to inhibit CaM-KII and protein kinase C. The results show that SYB is a potential substrate for protein kinases involved in the regulation of neurotransmitter release and open the possibility that phosphorylation of SYB plays a role in modulating the molecular interactions between synaptic vesicles and the Presynaptic Membrane.
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tetanus and botulinum neurotoxins turning bad guys into good by research
Toxicon, 2001Co-Authors: Ornella Rossetto, M Seveso, Paola Caccin, Giampietro Schiavo, Cesare MontecuccoAbstract:Abstract The neuroparalytic syndromes of tetanus and botulism are caused by neurotoxins produced by bacteria of the genus Clostridium . They are 150 kDa proteins consisting of three-domains, endowed with different functions: neurospecific binding, Membrane translocation and specific proteolysis of three key components of the neuroexocytosis apparatus. After binding to the Presynaptic Membrane of motoneurons, tetanus neurotoxin (TeNT) is internalized and transported retroaxonally to the spinal cord, where it blocks neurotransmitter release from spinal inhibitory interneurons. In contrast, the seven botulinum neurotoxins (BoNT) act at the periphery and inhibit acetylcholine release from peripheral cholinergic nerve terminals. TeNT and BoNT-B, -D, -F and -G cleave specifically at single but different peptide bonds, VAMP/synaptobrevin, a Membrane protein of small synaptic vesicles. BoNT types -A, -C and -E cleave SNAP-25 at different sites within the COOH-terminus, whereas BoNT-C also cleaves syntaxin. BoNTs are increasingly used in medicine for the treatment of human diseases characterized by hyperfunction of cholinergic terminals.
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tetanus and botulinum neurotoxins turning bad guys into good by research
Toxicon, 2001Co-Authors: Ornella Rossetto, M Seveso, Paola Caccin, Giampietro Schiavo, Cesare MontecuccoAbstract:Abstract The neuroparalytic syndromes of tetanus and botulism are caused by neurotoxins produced by bacteria of the genus Clostridium . They are 150 kDa proteins consisting of three-domains, endowed with different functions: neurospecific binding, Membrane translocation and specific proteolysis of three key components of the neuroexocytosis apparatus. After binding to the Presynaptic Membrane of motoneurons, tetanus neurotoxin (TeNT) is internalized and transported retroaxonally to the spinal cord, where it blocks neurotransmitter release from spinal inhibitory interneurons. In contrast, the seven botulinum neurotoxins (BoNT) act at the periphery and inhibit acetylcholine release from peripheral cholinergic nerve terminals. TeNT and BoNT-B, -D, -F and -G cleave specifically at single but different peptide bonds, VAMP/synaptobrevin, a Membrane protein of small synaptic vesicles. BoNT types -A, -C and -E cleave SNAP-25 at different sites within the COOH-terminus, whereas BoNT-C also cleaves syntaxin. BoNTs are increasingly used in medicine for the treatment of human diseases characterized by hyperfunction of cholinergic terminals.
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vesicle associated Membrane protein 2 synaptobrevin 2 forms a complex with synaptophysin
Biochemical Journal, 1995Co-Authors: Philip Washbourne, Giampietro SchiavoAbstract:Vesicle-associated Membrane protein (VAMP) (or synaptobrevin), a type II Membrane protein of small synaptic vesicles, is essential for neuroexocytosis because its proteolysis by tetanus and botulinum neurotoxins types B, D, F and G blocks neurotransmitter release. The addition of cross-linking reagents to isolated small synaptic vesicles induces the formation of 30 and 50 kDa complexes containing the isoform 2 of VAMP (VAMP-2). Whereas the 30 kDa band is a VAMP-2 homodimer, the 50 kDa species results from the cross-linking of VAMP-2 with synaptophysin. This heterodimer also forms in detergent-solubilized vesicles and involves the N-terminal part of VAMP-2. The implications of the existence of a synaptophysin-VAMP-2 complex in the processes of vesicle docking and fusion with the Presynaptic Membrane are discussed.
Ornella Rossetto - One of the best experts on this subject based on the ideXlab platform.
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Presynaptic receptor arrays for clostridial neurotoxins
Trends in Microbiology, 2004Co-Authors: Cesare Montecucco, Ornella Rossetto, Giampietro SchiavoAbstract:Tetanus and botulinum neurotoxins act at femtomolar concentrations and are specific for the Presynaptic Membrane of neurons. Their mode of binding is still poorly defined. The exceptional potency and specificity of these neurotoxins raise unprecedented questions about the nature of their receptor(s) and the mode of their Membrane binding. We propose a Presynaptic binding process for tetanus and botulinum neurotoxins based on a capture step performed by an antenna, consisting of a lipid- or a protein-linked oligosaccharide, which brings about a very large Membrane concentration effect; this is followed by additional interactions with arrays of receptor molecules, arranged in Membrane microdomains, which render the neurotoxin binding practically irreversible and triggers endocytosis.
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tetanus and botulinum neurotoxins turning bad guys into good by research
Toxicon, 2001Co-Authors: Ornella Rossetto, M Seveso, Paola Caccin, Giampietro Schiavo, Cesare MontecuccoAbstract:Abstract The neuroparalytic syndromes of tetanus and botulism are caused by neurotoxins produced by bacteria of the genus Clostridium . They are 150 kDa proteins consisting of three-domains, endowed with different functions: neurospecific binding, Membrane translocation and specific proteolysis of three key components of the neuroexocytosis apparatus. After binding to the Presynaptic Membrane of motoneurons, tetanus neurotoxin (TeNT) is internalized and transported retroaxonally to the spinal cord, where it blocks neurotransmitter release from spinal inhibitory interneurons. In contrast, the seven botulinum neurotoxins (BoNT) act at the periphery and inhibit acetylcholine release from peripheral cholinergic nerve terminals. TeNT and BoNT-B, -D, -F and -G cleave specifically at single but different peptide bonds, VAMP/synaptobrevin, a Membrane protein of small synaptic vesicles. BoNT types -A, -C and -E cleave SNAP-25 at different sites within the COOH-terminus, whereas BoNT-C also cleaves syntaxin. BoNTs are increasingly used in medicine for the treatment of human diseases characterized by hyperfunction of cholinergic terminals.
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tetanus and botulinum neurotoxins turning bad guys into good by research
Toxicon, 2001Co-Authors: Ornella Rossetto, M Seveso, Paola Caccin, Giampietro Schiavo, Cesare MontecuccoAbstract:Abstract The neuroparalytic syndromes of tetanus and botulism are caused by neurotoxins produced by bacteria of the genus Clostridium . They are 150 kDa proteins consisting of three-domains, endowed with different functions: neurospecific binding, Membrane translocation and specific proteolysis of three key components of the neuroexocytosis apparatus. After binding to the Presynaptic Membrane of motoneurons, tetanus neurotoxin (TeNT) is internalized and transported retroaxonally to the spinal cord, where it blocks neurotransmitter release from spinal inhibitory interneurons. In contrast, the seven botulinum neurotoxins (BoNT) act at the periphery and inhibit acetylcholine release from peripheral cholinergic nerve terminals. TeNT and BoNT-B, -D, -F and -G cleave specifically at single but different peptide bonds, VAMP/synaptobrevin, a Membrane protein of small synaptic vesicles. BoNT types -A, -C and -E cleave SNAP-25 at different sites within the COOH-terminus, whereas BoNT-C also cleaves syntaxin. BoNTs are increasingly used in medicine for the treatment of human diseases characterized by hyperfunction of cholinergic terminals.
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how do Presynaptic pla2 neurotoxins block nerve terminals
Trends in Biochemical Sciences, 2000Co-Authors: Cesare Montecucco, Ornella RossettoAbstract:Snake Presynaptic neurotoxins with phospholipase A2 activity block nerve terminals in an unknown way. Here, we propose that they enter the lumen of synaptic vesicles following endocytosis and hydrolyse phospholipids of the inner leaflet of the Membrane. The transMembrane pH gradient drives the translocation of fatty acids to the cytosolic monolayer, leaving lysophospholipids on the lumenal layer. Such vesicles are highly fusogenic and release neurotransmitter upon fusion with the Presynaptic Membrane, but cannot be retrieved because of the high local concentration of fatty acids and lysophospholipids, which prevents vesicle neck closure.
Volker Haucke - One of the best experts on this subject based on the ideXlab platform.
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molecular mechanisms of Presynaptic Membrane retrieval and synaptic vesicle reformation
Neuron, 2015Co-Authors: Volker Haucke, Natalia L KononenkoAbstract:The function of the nervous system depends on the exocytotic release of neurotransmitter from synaptic vesicles (SVs). To sustain neurotransmission, SV Membranes need to be retrieved, and SVs have to be reformed locally within Presynaptic nerve terminals. In spite of more than 40 years of research, the mechanisms underlying Presynaptic Membrane retrieval and SV recycling remain controversial. Here, we review the current state of knowledge in the field, focusing on the molecular mechanism involved in Presynaptic Membrane retrieval and SV reformation. We discuss the challenges associated with studying these pathways and present perspectives for future research.
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Dedicated endocytic adaptors for the retrieval of synaptobrevin 2 at synapses
2011Co-Authors: Seong Joo Koo, Dmytro Puchkov, Volker Haucke, Leibniz-institut Für MolekulareAbstract:Communication between neurons largely occurs at chemical synapses by conversion of electric to chemical signals. Chemical neurotransmission involves the action potential-driven release of neurotransmitters from synaptic vesicles (SVs) at Presynaptic nerve terminals. Fusion of SVs is driven by SNARE complex formation comprising synaptobrevin 2 on the SV Membrane and syntaxin 1A and SNAP-25 on the plasma Membrane. In order to maintain neurotransmission during repetitive stimulation and to prevent expansion of the Presynaptic plasma Membrane, exocytic SV fusion needs to be balanced by compensatory retrieval of SV components to regenerate functional vesicles. Our recent work has unraveled a mechanism by which the R-SNARE synaptobrevin 2, the most abundant SV protein and an essential player for exocytic fusion, is recycled from the Presynaptic Membrane. The SNARE motif of synaptobrevin 2 is directly recognized by the ANTH domains of AP180 and CALM, monomeric endocytic adaptors for clathrin-mediated endocytosis. Given that key residues involved in synaptobrevin 2-ANTH domain complex formation
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human stoned b interacts with ap 2 and synaptotagmin and facilitates clathrin coated vesicle uncoating
EMBO Reports, 2001Co-Authors: Kristin Walther, Stefan Honing, Michael Krauss, Kasim M Diril, Steffen Lemke, Doris Ricotta, Stephen E Kaiser, Volker HauckeAbstract:Synaptic vesicle biogenesis involves the recycling of synaptic vesicle components by clathrin-mediated endocytosis from the Presynaptic Membrane. stoned B, a protein encoded by the stoned locus in Drosophila melanogaster has been shown to regulate vesicle recycling by interacting with synaptotagmin. We report here the identification and characterization of a human homolog of stoned B (hStnB). Human stoned B is a brain-specific protein which co-enriches with other endocytic proteins such as AP-2 in a crude synaptic vesicle fraction and at nerve terminals. A domain with homology to the medium chain of adaptor complexes binds directly to both AP-2 and synaptotagmin and competes with AP-2 for the same binding site within synaptotagmin. Finally we show that the µ2 homology domain of hStnB stimulates the uncoating of both clathrin and AP-2 adaptors from clathrin-coated vesicles. We hypothesize that hStnB regulates synaptic vesicle recycling by facilitating vesicle uncoating.
Manuel Yepes - One of the best experts on this subject based on the ideXlab platform.
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Tissue-type plasminogen activator induces synaptic vesicle endocytosis in cerebral cortical neurons.
Neuroscience, 2016Co-Authors: Manuel Yepes, Enrique Torre, David Cuellar-giraldo, Fang Wu, Lihong ChengAbstract:Abstract The release of the serine proteinase tissue-type plasminogen activator (tPA) from the Presynaptic terminal of cerebral cortical neurons plays a central role in the development of synaptic plasticity, adaptation to metabolic stress and neuronal survival. Our earlier studies indicate that by inducing the recruitment of the cytoskeletal protein βII-spectrin and voltage-gated calcium channels to the active zone, tPA promotes Ca2+-dependent translocation of synaptic vesicles (SVs) to the synaptic release site where they release their load of neurotransmitters into the synaptic cleft. Here we used a combination of in vivo and in vitro experiments to investigate whether this effect leads to depletion of SVs in the Presynaptic terminal. Our data indicate that tPA promotes SV endocytosis via a mechanism that does not require the conversion of plasminogen into plasmin. Instead, we show that tPA induces calcineurin-mediated dynamin I dephosphorylation, which is followed by dynamin I-induced recruitment of the actin-binding protein profilin II to the Presynaptic Membrane, and profilin II-induced F-actin formation. We report that this tPA-induced sequence of events leads to the association of newly formed SVs with F-actin clusters in the endocytic zone. In summary, the data presented here indicate that following the exocytotic release of neurotransmitters tPA activates the mechanism whereby SVs are retrieved from the Presynaptic Membrane and endocytosed to replenish the pool of vesicles available for a new cycle of exocytosis. Together, these results indicate that in murine cerebral cortical neurons tPA plays a central role coupling SVs exocytosis and endocytosis.
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tissue type plasminogen activator triggers the synaptic vesicle cycle in cerebral cortical neurons
Journal of Cerebral Blood Flow and Metabolism, 2015Co-Authors: Enrique Torre, Manuel Yepes, Lihong Cheng, David Cuellargiraldo, Edyta K Bichler, Paul S GarciaAbstract:The active zone (AZ) is a thickening of the Presynaptic Membrane where exocytosis takes place. Chemical synapses contain neurotransmitter-loaded synaptic vesicles (SVs) that at rest are tethered away from the synaptic release site, but after the Presynaptic inflow of Ca(+2) elicited by an action potential translocate to the AZ to release their neurotransmitter load. We report that tissue-type plasminogen activator (tPA) is stored outside the AZ of cerebral cortical neurons, either intermixed with small clear-core vesicles or in direct contact with the Presynaptic Membrane. We found that cerebral ischemia-induced release of neuronal tPA, or treatment with recombinant tPA, recruits the cytoskeletal protein βII-spectrin to the AZ and promotes the binding of SVs to βII-spectrin, enlarging the population of SVs in proximity to the synaptic release site. This effect does not require the generation of plasmin and is followed by the recruitment of voltage gated calcium channels (VGCC) to the Presynaptic terminal that leads to Ca(+2)-dependent synapsin I phosphorylation, freeing SVs to translocate to the AZ to deliver their neurotransmitter load. Our studies indicate that tPA activates the SV cycle and induces the structural and functional changes in the synapse that are required for successful neurotransmission.