1
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Harris KM, Kuwajima M, Flores JC, Zito K. Synapse-specific structural plasticity that protects and refines local circuits during LTP and LTD. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230224. [PMID: 38853547 DOI: 10.1098/rstb.2023.0224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 01/05/2024] [Indexed: 06/11/2024] Open
Abstract
Synapses form trillions of connections in the brain. Long-term potentiation (LTP) and long-term depression (LTD) are cellular mechanisms vital for learning that modify the strength and structure of synapses. Three-dimensional reconstruction from serial section electron microscopy reveals three distinct pre- to post-synaptic arrangements: strong active zones (AZs) with tightly docked vesicles, weak AZs with loose or non-docked vesicles, and nascent zones (NZs) with a postsynaptic density but no presynaptic vesicles. Importantly, LTP can be temporarily saturated preventing further increases in synaptic strength. At the onset of LTP, vesicles are recruited to NZs, converting them to AZs. During recovery of LTP from saturation (1-4 h), new NZs form, especially on spines where AZs are most enlarged by LTP. Sentinel spines contain smooth endoplasmic reticulum (SER), have the largest synapses and form clusters with smaller spines lacking SER after LTP recovers. We propose a model whereby NZ plasticity provides synapse-specific AZ expansion during LTP and loss of weak AZs that drive synapse shrinkage during LTD. Spine clusters become functionally engaged during LTP or disassembled during LTD. Saturation of LTP or LTD probably acts to protect recently formed memories from ongoing plasticity and may account for the advantage of spaced over massed learning. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Kristen M Harris
- Department of Neuroscience and Center for Learning and Memory, The University of Texas at Austin , Austin, TX 78712, USA
| | - Masaaki Kuwajima
- Department of Neuroscience and Center for Learning and Memory, The University of Texas at Austin , Austin, TX 78712, USA
| | - Juan C Flores
- Center for Neuroscience, University of California , Davis, CA 95618, USA
| | - Karen Zito
- Center for Neuroscience, University of California , Davis, CA 95618, USA
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2
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Bruentgens F, Moreno Velasquez L, Stumpf A, Parthier D, Breustedt J, Benfenati F, Milovanovic D, Schmitz D, Orlando M. The Lack of Synapsin Alters Presynaptic Plasticity at Hippocampal Mossy Fibers in Male Mice. eNeuro 2024; 11:ENEURO.0330-23.2024. [PMID: 38866497 PMCID: PMC11223178 DOI: 10.1523/eneuro.0330-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 05/17/2024] [Accepted: 05/20/2024] [Indexed: 06/14/2024] Open
Abstract
Synapsins are highly abundant presynaptic proteins that play a crucial role in neurotransmission and plasticity via the clustering of synaptic vesicles. The synapsin III isoform is usually downregulated after development, but in hippocampal mossy fiber boutons, it persists in adulthood. Mossy fiber boutons express presynaptic forms of short- and long-term plasticity, which are thought to underlie different forms of learning. Previous research on synapsins at this synapse focused on synapsin isoforms I and II. Thus, a complete picture regarding the role of synapsins in mossy fiber plasticity is still missing. Here, we investigated presynaptic plasticity at hippocampal mossy fiber boutons by combining electrophysiological field recordings and transmission electron microscopy in a mouse model lacking all synapsin isoforms. We found decreased short-term plasticity, i.e., decreased facilitation and post-tetanic potentiation, but increased long-term potentiation in male synapsin triple knock-out (KO) mice. At the ultrastructural level, we observed more dispersed vesicles and a higher density of active zones in mossy fiber boutons from KO animals. Our results indicate that all synapsin isoforms are required for fine regulation of short- and long-term presynaptic plasticity at the mossy fiber synapse.
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Affiliation(s)
- Felicitas Bruentgens
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
| | - Laura Moreno Velasquez
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
| | - Alexander Stumpf
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
| | - Daniel Parthier
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
| | - Jörg Breustedt
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa 16163, Italy
- IRCCS Ospedale Policlinico San Martino, Genoa 16132, Italy
| | - Dragomir Milovanovic
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin 10117, Germany
- Einstein Center for Neurosciences, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität Berlin, Berlin 10117, Germany
| | - Dietmar Schmitz
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin 13125, Germany
- German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin 10117, Germany
- Einstein Center for Neurosciences, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität Berlin, Berlin 10117, Germany
- Bernstein Center for Computational Neuroscience, Humboldt-Universität zu Berlin, Berlin 10115, Germany
| | - Marta Orlando
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
- NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin 10117, Germany
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3
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Wang C, Zhang K, Cai B, Haller JE, Carnazza KE, Hu J, Zhao C, Tian Z, Hu X, Hall D, Qiang J, Hou S, Liu Z, Gu J, Zhang Y, Seroogy KB, Burré J, Fang Y, Liu C, Brunger AT, Li D, Diao J. VAMP2 chaperones α-synuclein in synaptic vesicle co-condensates. Nat Cell Biol 2024:10.1038/s41556-024-01456-1. [PMID: 38951706 DOI: 10.1038/s41556-024-01456-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 06/05/2024] [Indexed: 07/03/2024]
Abstract
α-Synuclein (α-Syn) aggregation is closely associated with Parkinson's disease neuropathology. Physiologically, α-Syn promotes synaptic vesicle (SV) clustering and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly. However, the underlying structural and molecular mechanisms are uncertain and it is not known whether this function affects the pathological aggregation of α-Syn. Here we show that the juxtamembrane region of vesicle-associated membrane protein 2 (VAMP2)-a component of the SNARE complex that resides on SVs-directly interacts with the carboxy-terminal region of α-Syn through charged residues to regulate α-Syn's function in clustering SVs and promoting SNARE complex assembly by inducing a multi-component condensed phase of SVs, α-Syn and other components. Moreover, VAMP2 binding protects α-Syn against forming aggregation-prone oligomers and fibrils in these condensates. Our results suggest a molecular mechanism that maintains α-Syn's function and prevents its pathological amyloid aggregation, the failure of which may lead to Parkinson's disease.
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Affiliation(s)
- Chuchu Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
- University of Chinese Academy of Sciences, Beijing, China
| | - Kai Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Bin Cai
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Jillian E Haller
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Kathryn E Carnazza
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Jiaojiao Hu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chunyu Zhao
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhiqi Tian
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Xiao Hu
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Daniel Hall
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Jiali Qiang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Shouqiao Hou
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhenying Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jinge Gu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yaoyang Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Kim B Seroogy
- Department of Neurology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Jacqueline Burré
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Yanshan Fang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Dan Li
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China.
- Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai, China.
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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4
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Lippmann K. A Reduction in the Readily Releasable Vesicle Pool Impairs GABAergic Inhibition in the Hippocampus after Blood-Brain Barrier Dysfunction. Int J Mol Sci 2024; 25:6862. [PMID: 38999971 DOI: 10.3390/ijms25136862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/14/2024] Open
Abstract
Major burdens for patients suffering from stroke are cognitive co-morbidities and epileptogenesis. Neural network disinhibition and deficient inhibitive pulses for fast network activities may result from impaired presynaptic release of the inhibitory neurotransmitter GABA. To test this hypothesis, a cortical photothrombotic stroke was induced in Sprague Dawley rats, and inhibitory currents were recorded seven days later in the peri-infarct blood-brain barrier disrupted (BBBd) hippocampus via patch-clamp electrophysiology in CA1 pyramidal cells (PC). Miniature inhibitory postsynaptic current (mIPSC) frequency was reduced to about half, and mIPSCs decayed faster in the BBBd hippocampus. Furthermore, the paired-pulse ratio of evoked GABA release was increased at 100 Hz, and train stimulations with 100 Hz revealed that the readily releasable pool (RRP), usually assumed to correspond to the number of tightly docked presynaptic vesicles, is reduced by about half in the BBBd hippocampus. These pathophysiologic changes are likely to contribute significantly to disturbed fast oscillatory activity, like cognition-associated gamma oscillations or sharp wave ripples and epileptogenesis in the BBBd hippocampus.
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Affiliation(s)
- Kristina Lippmann
- Carl-Ludwig-Institute for Physiology, Medical Faculty, Leipzig University, D-04103 Leipzig, Germany
- Grass Laboratory, Marine Biological Laboratory, Woods Hole, MA 02543, USA
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5
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Lamanna J, Gloria G, Villa A, Malgaroli A. Anomalous diffusion of synaptic vesicles and its influences on spontaneous and evoked neurotransmission. J Physiol 2024; 602:2873-2898. [PMID: 38723211 DOI: 10.1113/jp284926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 04/22/2024] [Indexed: 06/15/2024] Open
Abstract
Neurons in the central nervous system communicate with each other by activating billions of tiny synaptic boutons distributed along their fine axons. These presynaptic varicosities are very crowded environments, comprising hundreds of synaptic vesicles. Only a fraction of these vesicles can be recruited in a single release episode, either spontaneous or evoked by action potentials. Since the seminal work by Fatt and Katz, spontaneous release has been modelled as a memoryless process. Nevertheless, at central synapses, experimental evidence indicates more complex features, including non-exponential distributions of release intervals and power-law behaviour in their rate. To describe these features, we developed a probabilistic model of spontaneous release based on Brownian motion of synaptic vesicles in the presynaptic environment. To account for different diffusion regimes, we based our simulations on fractional Brownian motion. We show that this model can predict both deviation from the Poisson hypothesis and power-law features in experimental quantal release series, thus suggesting that the vesicular motion by diffusion could per se explain the emergence of these properties. We demonstrate the efficacy of our modelling approach using electrophysiological recordings at single synaptic boutons and ultrastructural data. When this approach was used to simulate evoked responses, we found that the replenishment of the readily releasable pool driven by Brownian motion of vesicles can reproduce the characteristic binomial release distributions seen experimentally. We believe that our modelling approach supports the idea that vesicle diffusion and readily releasable pool dynamics are crucial factors for the physiological functioning of neuronal communication. KEY POINTS: We developed a new probabilistic model of spontaneous and evoked vesicle fusion based on simple biophysical assumptions, including the motion of vesicles before they dock to the release site. We provide closed-form equations for the interval distribution of spontaneous releases in the special case of Brownian diffusion of vesicles, showing that a power-law heavy tail is generated. Fractional Brownian motion (fBm) was exploited to simulate anomalous vesicle diffusion, including directed and non-directed motion, by varying the Hurst exponent. We show that our model predicts non-linear features observed in experimental spontaneous quantal release series as well as ultrastructural data of synaptic vesicles spatial distribution. Evoked exocytosis based on a diffusion-replenished readily releasable pool might explain the emergence of power-law behaviour in neuronal activity.
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Affiliation(s)
- Jacopo Lamanna
- Center for Behavioral Neuroscience and Communication (BNC), Vita-Salute San Raffaele University, Milan, Italy
- Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy
| | - Giulia Gloria
- Center for Behavioral Neuroscience and Communication (BNC), Vita-Salute San Raffaele University, Milan, Italy
| | | | - Antonio Malgaroli
- Center for Behavioral Neuroscience and Communication (BNC), Vita-Salute San Raffaele University, Milan, Italy
- Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy
- San Raffaele Turro, IRCCS Ospedale San Raffaele, Milan, Italy
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6
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Leitz J, Wang C, Esquivies L, Pfuetzner RA, Peters JJ, Couoh-Cardel S, Wang AL, Brunger AT. Beyond the MUN domain, Munc13 controls priming and depriming of synaptic vesicles. Cell Rep 2024; 43:114026. [PMID: 38809756 DOI: 10.1016/j.celrep.2024.114026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 02/20/2024] [Accepted: 03/15/2024] [Indexed: 05/31/2024] Open
Abstract
Synaptic vesicle docking and priming are dynamic processes. At the molecular level, SNAREs (soluble NSF attachment protein receptors), synaptotagmins, and other factors are critical for Ca2+-triggered vesicle exocytosis, while disassembly factors, including NSF (N-ethylmaleimide-sensitive factor) and α-SNAP (soluble NSF attachment protein), disassemble and recycle SNAREs and antagonize fusion under some conditions. Here, we introduce a hybrid fusion assay that uses synaptic vesicles isolated from mouse brains and synthetic plasma membrane mimics. We included Munc18, Munc13, complexin, NSF, α-SNAP, and an ATP-regeneration system and maintained them continuously-as in the neuron-to investigate how these opposing processes yield fusogenic synaptic vesicles. In this setting, synaptic vesicle association is reversible, and the ATP-regeneration system produces the most synchronous Ca2+-triggered fusion, suggesting that disassembly factors perform quality control at the early stages of synaptic vesicle association to establish a highly fusogenic state. We uncovered a functional role for Munc13 ancillary to the MUN domain that alleviates an α-SNAP-dependent inhibition of Ca2+-triggered fusion.
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Affiliation(s)
- Jeremy Leitz
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA; Department of Structural Biology, Stanford University, Stanford, CA, USA; Department of Photon Science, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Chuchu Wang
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA; Department of Structural Biology, Stanford University, Stanford, CA, USA; Department of Photon Science, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Luis Esquivies
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA; Department of Structural Biology, Stanford University, Stanford, CA, USA; Department of Photon Science, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Richard A Pfuetzner
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA; Department of Structural Biology, Stanford University, Stanford, CA, USA; Department of Photon Science, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - John Jacob Peters
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA; Department of Structural Biology, Stanford University, Stanford, CA, USA; Department of Photon Science, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Sergio Couoh-Cardel
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA; Department of Structural Biology, Stanford University, Stanford, CA, USA; Department of Photon Science, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Austin L Wang
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA; Department of Structural Biology, Stanford University, Stanford, CA, USA; Department of Photon Science, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA; Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA; Department of Structural Biology, Stanford University, Stanford, CA, USA; Department of Photon Science, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA.
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7
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Aldahabi M, Neher E, Nusser Z. Different states of synaptic vesicle priming explain target cell type-dependent differences in neurotransmitter release. Proc Natl Acad Sci U S A 2024; 121:e2322550121. [PMID: 38657053 PMCID: PMC11067035 DOI: 10.1073/pnas.2322550121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Accepted: 03/27/2024] [Indexed: 04/26/2024] Open
Abstract
Pronounced differences in neurotransmitter release from a given presynaptic neuron, depending on the synaptic target, are among the most intriguing features of cortical networks. Hippocampal pyramidal cells (PCs) release glutamate with low probability to somatostatin expressing oriens-lacunosum-moleculare (O-LM) interneurons (INs), and the postsynaptic responses show robust short-term facilitation, whereas the release from the same presynaptic axons onto fast-spiking INs (FSINs) is ~10-fold higher and the excitatory postsynaptic currents (EPSCs) display depression. The mechanisms underlying these vastly different synaptic behaviors have not been conclusively identified. Here, we applied a combined functional, pharmacological, and modeling approach to address whether the main difference lies in the action potential-evoked fusion or else in upstream priming processes of synaptic vesicles (SVs). A sequential two-step SV priming model was fitted to the peak amplitudes of unitary EPSCs recorded in response to complex trains of presynaptic stimuli in acute hippocampal slices of adult mice. At PC-FSIN connections, the fusion probability (Pfusion) of well-primed SVs is 0.6, and 44% of docked SVs are in a fusion-competent state. At PC-O-LM synapses, Pfusion is only 40% lower (0.36), whereas the fraction of well-primed SVs is 6.5-fold smaller. Pharmacological enhancement of fusion by 4-AP and priming by PDBU was recaptured by the model with a selective increase of Pfusion and the fraction of well-primed SVs, respectively. Our results demonstrate that the low fidelity of transmission at PC-O-LM synapses can be explained by a low occupancy of the release sites by well-primed SVs.
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Affiliation(s)
- Mohammad Aldahabi
- Laboratory of Cellular Neurophysiology, Hungarian Research Network Institute of Experimental Medicine, Budapest1083, Hungary
- János Szentágothai School of Neurosciences, Semmelweis University, Budapest1085, Hungary
| | - Erwin Neher
- Laboratory of Membrane Biophysics, Max Planck Institute for Multidisciplinary Sciences, 37077Göttingen, Germany
| | - Zoltan Nusser
- Laboratory of Cellular Neurophysiology, Hungarian Research Network Institute of Experimental Medicine, Budapest1083, Hungary
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8
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Xu J, Esser V, Gołębiowska-Mendroch K, Bolembach AA, Rizo J. Control of Munc13-1 Activity by Autoinhibitory Interactions Involving the Variable N-terminal Region. J Mol Biol 2024; 436:168502. [PMID: 38417672 DOI: 10.1016/j.jmb.2024.168502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/17/2024] [Accepted: 02/20/2024] [Indexed: 03/01/2024]
Abstract
Regulation of neurotransmitter release during presynaptic plasticity underlies varied forms of information processing in the brain. Munc13s play essential roles in release via their conserved C-terminal region, which contains a MUN domain involved in SNARE complex assembly, and controls multiple presynaptic plasticity processes. Munc13s also have a variable N-terminal region, which in Munc13-1 includes a calmodulin binding (CaMb) domain involved in short-term plasticity and a C2A domain that forms an inhibitory homodimer. The C2A domain is activated by forming a heterodimer with the zinc-finger domain of αRIMs, providing a link to αRIM-dependent short- and long-term plasticity. However, it is unknown how the functions of the N- and C-terminal regions are integrated, in part because of the difficulty of purifying Munc13-1 fragments containing both regions. We describe for the first time the purification of a Munc13-1 fragment spanning its entire sequence except for a flexible region between the C2A and CaMb domains. We show that this fragment is much less active than the Munc13-1 C-terminal region in liposome fusion assays and that its activity is strongly enhanced by the RIM2α zinc-finger domain together with calmodulin. NMR experiments show that the C2A and CaMb domains bind to the MUN domain and that these interactions are relieved by the RIM2α ZF domain and calmodulin, respectively. These results suggest a model whereby Munc13-1 activity in promoting SNARE complex assembly and neurotransmitter release are inhibited by interactions of the C2A and CaMb domains with the MUN domain that are relieved by αRIMs and calmodulin.
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Affiliation(s)
- Junjie Xu
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Victoria Esser
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Katarzyna Gołębiowska-Mendroch
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Agnieszka A Bolembach
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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9
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López-Murcia FJ, Lin KH, Berns MMM, Ranjan M, Lipstein N, Neher E, Brose N, Reim K, Taschenberger H. Complexin has a dual synaptic function as checkpoint protein in vesicle priming and as a promoter of vesicle fusion. Proc Natl Acad Sci U S A 2024; 121:e2320505121. [PMID: 38568977 PMCID: PMC11009659 DOI: 10.1073/pnas.2320505121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 03/04/2024] [Indexed: 04/05/2024] Open
Abstract
The presynaptic SNARE-complex regulator complexin (Cplx) enhances the fusogenicity of primed synaptic vesicles (SVs). Consequently, Cplx deletion impairs action potential-evoked transmitter release. Conversely, though, Cplx loss enhances spontaneous and delayed asynchronous release at certain synapse types. Using electrophysiology and kinetic modeling, we show that such seemingly contradictory transmitter release phenotypes seen upon Cplx deletion can be explained by an additional of Cplx in the control of SV priming, where its ablation facilitates the generation of a "faulty" SV fusion apparatus. Supporting this notion, a sequential two-step priming scheme, featuring reduced vesicle fusogenicity and increased transition rates into the faulty primed state, reproduces all aberrations of transmitter release modes and short-term synaptic plasticity seen upon Cplx loss. Accordingly, we propose a dual presynaptic function for the SNARE-complex interactor Cplx, one as a "checkpoint" protein that guarantees the proper assembly of the fusion machinery during vesicle priming, and one in boosting vesicle fusogenicity.
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Affiliation(s)
- Francisco José López-Murcia
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
| | - Kun-Han Lin
- Laboratory of Membrane Biophysics, Max Planck Institute for Multidisciplinary Sciences, Göttingen37077, Germany
| | - Manon M. M. Berns
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
| | - Mrinalini Ranjan
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
- Göttingen Graduate School for Neurosciences, Biophysics, and Molecular Biosciences, Georg August University Göttingen, Göttingen37077, Germany
| | - Noa Lipstein
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
| | - Erwin Neher
- Laboratory of Membrane Biophysics, Max Planck Institute for Multidisciplinary Sciences, Göttingen37077, Germany
- Cluster of Excellence ‘Multiscale Bioimaging’, Georg August University Göttingen, Göttingen37073, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
- Cluster of Excellence ‘Multiscale Bioimaging’, Georg August University Göttingen, Göttingen37073, Germany
| | - Kerstin Reim
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
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10
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Patil SS, Sanghrajka K, Sriram M, Chakraborty A, Majumdar S, Bhaskar BR, Das D. Synaptobrevin2 monomers and dimers differentially engage to regulate the functional trans-SNARE assembly. Life Sci Alliance 2024; 7:e202402568. [PMID: 38238088 PMCID: PMC10796598 DOI: 10.26508/lsa.202402568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 01/12/2024] [Accepted: 01/12/2024] [Indexed: 01/22/2024] Open
Abstract
The precise cell-to-cell communication relies on SNARE-catalyzed membrane fusion. Among ∼70 copies of synaptobrevin2 (syb2) in synaptic vesicles, only ∼3 copies are sufficient to facilitate the fusion process at the presynaptic terminal. It is unclear what dictates the number of SNARE complexes that constitute the fusion pore assembly. The structure-function relation of these dynamic pores is also unknown. Here, we demonstrate that syb2 monomers and dimers differentially engage in regulating the trans-SNARE assembly during membrane fusion. The differential recruitment of two syb2 structures at the membrane fusion site has consequences in regulating individual nascent fusion pore properties. We have identified a few syb2 transmembrane domain residues that control monomer/dimer conversion. Overall, our study indicates that syb2 monomers and dimers are differentially recruited at the release sites for regulating membrane fusion events.
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Affiliation(s)
- Swapnali S Patil
- https://ror.org/03ht1xw27 Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Kinjal Sanghrajka
- https://ror.org/03ht1xw27 Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Malavika Sriram
- https://ror.org/03ht1xw27 Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Aritra Chakraborty
- https://ror.org/03ht1xw27 Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Sougata Majumdar
- https://ror.org/03ht1xw27 Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Bhavya R Bhaskar
- https://ror.org/03ht1xw27 Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Debasis Das
- https://ror.org/03ht1xw27 Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
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11
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Herrera-Zamora JM, Osuna-Lopez F, Reyes-Méndez ME, Valadez-Lemus RE, Sánchez-Pastor EA, Navarro-Polanco RA, Moreno-Galindo EG, Alamilla J. Increased glutamatergic neurotransmission between the retinohypothalamic tract and the suprachiasmatic nucleus of old mice. J Neurosci Res 2024; 102:e25331. [PMID: 38651314 DOI: 10.1002/jnr.25331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 03/11/2024] [Accepted: 04/03/2024] [Indexed: 04/25/2024]
Abstract
Circadian rhythms synchronize to light through the retinohypothalamic tract (RHT), which is a bundle of axons coming from melanopsin retinal ganglion cells, whose synaptic terminals release glutamate to the ventral suprachiasmatic nucleus (SCN). Activation of AMPA-kainate and NMDA postsynaptic receptors elicits the increase in intracellular calcium required for triggering the signaling cascade that ends in phase shifts. During aging, there is a decline in the synchronization of circadian rhythms to light. With electrophysiological (whole-cell patch-clamp) and immunohistochemical assays, in this work, we studied pre- and postsynaptic properties between the RHT and ventral SCN neurons in young adult (P90-120) and old (P540-650) C57BL/6J mice. Incremental stimulation intensities (applied on the optic chiasm) induced much lesser AMPA-kainate postsynaptic responses in old animals, implying a lower recruitment of RHT fibers. Conversely, a higher proportion of old SCN neurons exhibited synaptic facilitation, and variance-mean analysis indicated an increase in the probability of release in RHT terminals. Moreover, both spontaneous and miniature postsynaptic events displayed larger amplitudes in neurons from aged mice, whereas analysis of the NMDA and AMPA-kainate components (evoked by RHT electrical stimulation) disclosed no difference between the two ages studied. Immunohistochemistry revealed a bigger size in the puncta of vGluT2, GluN2B, and GluN2A of elderly animals, and the number of immunopositive particles was increased, but that of PSD-95 was reduced. All these synaptic adaptations could be part of compensatory mechanisms in the glutamatergic signaling to ameliorate the loss of RHT terminals in old animals.
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Affiliation(s)
- J Manuel Herrera-Zamora
- Centro Universitario de Investigaciones Biomédicas (CUIB), Universidad de Colima, Colima, Mexico
| | - Fernando Osuna-Lopez
- Centro Universitario de Investigaciones Biomédicas (CUIB), Universidad de Colima, Colima, Mexico
| | - Miriam E Reyes-Méndez
- Centro Universitario de Investigaciones Biomédicas (CUIB), Universidad de Colima, Colima, Mexico
| | - Ramon E Valadez-Lemus
- Centro Universitario de Investigaciones Biomédicas (CUIB), Universidad de Colima, Colima, Mexico
| | - Enrique A Sánchez-Pastor
- Centro Universitario de Investigaciones Biomédicas (CUIB), Universidad de Colima, Colima, Mexico
| | | | - Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas (CUIB), Universidad de Colima, Colima, Mexico
| | - Javier Alamilla
- Centro Universitario de Investigaciones Biomédicas (CUIB), Universidad de Colima, Colima, Mexico
- Consejo Nacional de Humanidades, Ciencia y Tecnología (CONAHCYT), Universidad de Colima, Colima, Mexico
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12
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Xue R, Zhang E, Wang Y. Pre-fusion motion state determines the heterogeneity of membrane fusion dynamics for large dense-core vesicles. Acta Physiol (Oxf) 2024; 240:e14115. [PMID: 38353019 DOI: 10.1111/apha.14115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 11/30/2023] [Accepted: 02/02/2024] [Indexed: 04/17/2024]
Abstract
AIM In neuroendocrine cells, large dense-core vesicles (LDCVs) undergo highly regulated pre-fusion processes before releasing hormones via membrane fusion. Significant heterogeneity has been found for LDCV population based on the dynamics of membrane fusion. However, how the pre-fusion status impacts the heterogeneity of LDCVs still remains unclear. Hence, we explored pre-fusion determinants of heterogeneous membrane fusion procedure of LDCV subpopulations. METHODS We assessed the pre-fusion motion of two LDCV subpopulations with distinct membrane fusion dynamics individually, using total internal reflection fluorescence microscopy. These two subpopulations were isolated by blocking Rho GTPase-dependent actin reorganization using Clostridium difficile toxin B (ToxB), which selectively targets the fast fusion vesicle pool. RESULTS We found that the fast fusion subpopulation was in an active motion mode prior to release, termed "active" LDCV pool, while vesicles from the slow fusion subpopulation were also moving but in a significantly more confined status, forming an "inert" pool. The depletion of the active pool by ToxB also eliminated fast fusion vesicles and was not rescued by pre-treatment with phorbol ester. A mild actin reorganization blocker, latrunculin A, that partially disrupted the active pool, only slightly attenuated the fast fusion subpopulation. CONCLUSION The pre-fusion motion state of LDCVs also exhibits heterogeneity and dictates the heterogeneous fusion pore dynamics. Rearrangement of F-actin network mediates vesicle pre-fusion motion and subsequently determines the membrane fusion kinetics.
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Affiliation(s)
- Renhao Xue
- Shanghai Key Laboratory of Maternal Fetal Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
- Department of Gynecology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Enming Zhang
- Department of Clinical Sciences in Malmö, Lund University Diabetes Centre, Lund University, Malmö, Sweden
| | - Yu Wang
- Shanghai Key Laboratory of Maternal Fetal Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
- Department of Gynecology, Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, China
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13
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Wu Z, Kusick GF, Berns MMM, Raychaudhuri S, Itoh K, Walter AM, Chapman ER, Watanabe S. Synaptotagmin 7 docks synaptic vesicles to support facilitation and Doc2α-triggered asynchronous release. eLife 2024; 12:RP90632. [PMID: 38536730 PMCID: PMC10972563 DOI: 10.7554/elife.90632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024] Open
Abstract
Despite decades of intense study, the molecular basis of asynchronous neurotransmitter release remains enigmatic. Synaptotagmin (syt) 7 and Doc2 have both been proposed as Ca2+ sensors that trigger this mode of exocytosis, but conflicting findings have led to controversy. Here, we demonstrate that at excitatory mouse hippocampal synapses, Doc2α is the major Ca2+ sensor for asynchronous release, while syt7 supports this process through activity-dependent docking of synaptic vesicles. In synapses lacking Doc2α, asynchronous release after single action potentials is strongly reduced, while deleting syt7 has no effect. However, in the absence of syt7, docked vesicles cannot be replenished on millisecond timescales. Consequently, both synchronous and asynchronous release depress from the second pulse onward during repetitive activity. By contrast, synapses lacking Doc2α have normal activity-dependent docking, but continue to exhibit decreased asynchronous release after multiple stimuli. Moreover, disruption of both Ca2+ sensors is non-additive. These findings result in a new model whereby syt7 drives activity-dependent docking, thus providing synaptic vesicles for synchronous (syt1) and asynchronous (Doc2 and other unidentified sensors) release during ongoing transmission.
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Affiliation(s)
- Zhenyong Wu
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
- Howard Hughes Medical InstituteMadisonUnited States
| | - Grant F Kusick
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
- Biochemistry, Cellular and Molecular Biology Graduate Program, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Manon MM Berns
- Department of Neuroscience, University of CopenhagenCopenhagenDenmark
| | - Sumana Raychaudhuri
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
| | - Kie Itoh
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
| | - Alexander M Walter
- Department of Neuroscience, University of CopenhagenCopenhagenDenmark
- Molecular and Theoretical Neuroscience, Leibniz-Institut für Molekulare Pharmakologie, FMP im CharitéCrossOverBerlinGermany
| | - Edwin R Chapman
- Department of Neuroscience, University of Wisconsin-MadisonMadisonUnited States
- Howard Hughes Medical InstituteMadisonUnited States
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University, School of MedicineBaltimoreUnited States
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of MedicineBaltimoreUnited States
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14
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Meijer M, Öttl M, Yang J, Subkhangulova A, Kumar A, Feng Z, van Voorst TW, Groffen AJ, van Weering JRT, Zhang Y, Verhage M. Tomosyns attenuate SNARE assembly and synaptic depression by binding to VAMP2-containing template complexes. Nat Commun 2024; 15:2652. [PMID: 38531902 PMCID: PMC10965968 DOI: 10.1038/s41467-024-46828-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 03/12/2024] [Indexed: 03/28/2024] Open
Abstract
Tomosyns are widely thought to attenuate membrane fusion by competing with synaptobrevin-2/VAMP2 for SNARE-complex assembly. Here, we present evidence against this scenario. In a novel mouse model, tomosyn-1/2 deficiency lowered the fusion barrier and enhanced the probability that synaptic vesicles fuse, resulting in stronger synapses with faster depression and slower recovery. While wild-type tomosyn-1m rescued these phenotypes, substitution of its SNARE motif with that of synaptobrevin-2/VAMP2 did not. Single-molecule force measurements indeed revealed that tomosyn's SNARE motif cannot substitute synaptobrevin-2/VAMP2 to form template complexes with Munc18-1 and syntaxin-1, an essential intermediate for SNARE assembly. Instead, tomosyns extensively bind synaptobrevin-2/VAMP2-containing template complexes and prevent SNAP-25 association. Structure-function analyses indicate that the C-terminal polybasic region contributes to tomosyn's inhibitory function. These results reveal that tomosyns regulate synaptic transmission by cooperating with synaptobrevin-2/VAMP2 to prevent SNAP-25 binding during SNARE assembly, thereby limiting initial synaptic strength and equalizing it during repetitive stimulation.
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Affiliation(s)
- Marieke Meijer
- Department of Human Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam University Medical Center, 1081HV, Amsterdam, The Netherlands.
| | - Miriam Öttl
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, 1081HV, Amsterdam, The Netherlands
| | - Jie Yang
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, 06511, USA.
| | - Aygul Subkhangulova
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, 1081HV, Amsterdam, The Netherlands
| | - Avinash Kumar
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, 06511, USA
| | - Zicheng Feng
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, 06511, USA
| | - Torben W van Voorst
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, 1081HV, Amsterdam, The Netherlands
| | - Alexander J Groffen
- Department of Human Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam University Medical Center, 1081HV, Amsterdam, The Netherlands
| | - Jan R T van Weering
- Department of Human Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam University Medical Center, 1081HV, Amsterdam, The Netherlands
| | - Yongli Zhang
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, 06511, USA.
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06511, USA.
| | - Matthijs Verhage
- Department of Human Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam University Medical Center, 1081HV, Amsterdam, The Netherlands.
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, 1081HV, Amsterdam, The Netherlands.
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15
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Quintanilla J, Jia Y, Pruess BS, Chavez J, Gall CM, Lynch G, Gunn BG. Pre- versus Post-synaptic Forms of LTP in Two Branches of the Same Hippocampal Afferent. J Neurosci 2024; 44:e1449232024. [PMID: 38326038 PMCID: PMC10919254 DOI: 10.1523/jneurosci.1449-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 12/18/2023] [Accepted: 01/22/2024] [Indexed: 02/09/2024] Open
Abstract
There has been considerable controversy about pre- versus postsynaptic expression of memory-related long-term potentiation (LTP), with corresponding disputes about underlying mechanisms. We report here an instance in male mice, in which both types of potentiation are expressed but in separate branches of the same hippocampal afferent. Induction of LTP in the dentate gyrus (DG) branch of the lateral perforant path (LPP) reduces paired-pulse facilitation, is blocked by antagonism of cannabinoid receptor type 1, and is not affected by suppression of postsynaptic actin polymerization. These observations are consistent with presynaptic expression. The opposite pattern of results was obtained in the LPP branch that innervates the distal dendrites of CA3: LTP did not reduce paired-pulse facilitation, was unaffected by the cannabinoid receptor blocker, and required postsynaptic actin filament assembly. Differences in the two LPP termination sites were also noted for frequency facilitation of synaptic responses, an effect that was reproduced in a two-step simulation by small adjustments to vesicle release dynamics. These results indicate that different types of glutamatergic neurons impose different forms of filtering and synaptic plasticity on their afferents. They also suggest that inputs are routed to, and encoded by, different sites within the hippocampus depending upon the pattern of activity arriving over the parent axon.
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Affiliation(s)
- J Quintanilla
- Department of Anatomy & Neurobiology, University of California, Irvine, California 92697
| | - Y Jia
- Department of Anatomy & Neurobiology, University of California, Irvine, California 92697
| | - B S Pruess
- Department of Anatomy & Neurobiology, University of California, Irvine, California 92697
| | - J Chavez
- Department of Anatomy & Neurobiology, University of California, Irvine, California 92697
| | - C M Gall
- Department of Anatomy & Neurobiology, University of California, Irvine, California 92697
- Neurobiology & Behavior, University of California, Irvine, California 92697
| | - G Lynch
- Department of Anatomy & Neurobiology, University of California, Irvine, California 92697
- Psychiatry & Human Behavior, University of California, Irvine, California 92697
| | - B G Gunn
- Department of Anatomy & Neurobiology, University of California, Irvine, California 92697
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16
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Koppensteiner P, Bhandari P, Önal C, Borges-Merjane C, Le Monnier E, Roy U, Nakamura Y, Sadakata T, Sanbo M, Hirabayashi M, Rhee J, Brose N, Jonas P, Shigemoto R. GABA B receptors induce phasic release from medial habenula terminals through activity-dependent recruitment of release-ready vesicles. Proc Natl Acad Sci U S A 2024; 121:e2301449121. [PMID: 38346189 PMCID: PMC10895368 DOI: 10.1073/pnas.2301449121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 01/03/2024] [Indexed: 02/15/2024] Open
Abstract
GABAB receptor (GBR) activation inhibits neurotransmitter release in axon terminals in the brain, except in medial habenula (MHb) terminals, which show robust potentiation. However, mechanisms underlying this enigmatic potentiation remain elusive. Here, we report that GBR activation on MHb terminals induces an activity-dependent transition from a facilitating, tonic to a depressing, phasic neurotransmitter release mode. This transition is accompanied by a 4.1-fold increase in readily releasable vesicle pool (RRP) size and a 3.5-fold increase of docked synaptic vesicles (SVs) at the presynaptic active zone (AZ). Strikingly, the depressing phasic release exhibits looser coupling distance than the tonic release. Furthermore, the tonic and phasic release are selectively affected by deletion of synaptoporin (SPO) and Ca2+-dependent activator protein for secretion 2 (CAPS2), respectively. SPO modulates augmentation, the short-term plasticity associated with tonic release, and CAPS2 retains the increased RRP for initial responses in phasic response trains. The cytosolic protein CAPS2 showed a SV-associated distribution similar to the vesicular transmembrane protein SPO, and they were colocalized in the same terminals. We developed the "Flash and Freeze-fracture" method, and revealed the release of SPO-associated vesicles in both tonic and phasic modes and activity-dependent recruitment of CAPS2 to the AZ during phasic release, which lasted several minutes. Overall, these results indicate that GBR activation translocates CAPS2 to the AZ along with the fusion of CAPS2-associated SVs, contributing to persistency of the RRP increase. Thus, we identified structural and molecular mechanisms underlying tonic and phasic neurotransmitter release and their transition by GBR activation in MHb terminals.
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Affiliation(s)
| | - Pradeep Bhandari
- Institute of Science and Technology Austria, Klosterneuburg3400, Austria
| | - Cihan Önal
- Institute of Science and Technology Austria, Klosterneuburg3400, Austria
| | | | - Elodie Le Monnier
- Institute of Science and Technology Austria, Klosterneuburg3400, Austria
| | - Utsa Roy
- Institute of Science and Technology Austria, Klosterneuburg3400, Austria
| | - Yukihiro Nakamura
- Department of Pharmacology, Jikei University School of Medicine, Nishishinbashi, Minato-ku, Tokyo105-8461, Japan
| | - Tetsushi Sadakata
- Advanced Scientific Research Leaders Development Unit, Gunma University Graduate School of Medicine, Maebashi, Gunma371-8511, Japan
| | - Makoto Sanbo
- Section of Mammalian Transgenesis, National Institute for Physiological Sciences, Okazaki444-8585, Japan
| | - Masumi Hirabayashi
- Section of Mammalian Transgenesis, National Institute for Physiological Sciences, Okazaki444-8585, Japan
| | - JeongSeop Rhee
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37077, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37077, Germany
| | - Peter Jonas
- Institute of Science and Technology Austria, Klosterneuburg3400, Austria
| | - Ryuichi Shigemoto
- Institute of Science and Technology Austria, Klosterneuburg3400, Austria
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17
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Miyano R, Sakamoto H, Hirose K, Sakaba T. RIM-BP2 regulates Ca 2+ channel abundance and neurotransmitter release at hippocampal mossy fiber terminals. eLife 2024; 12:RP90799. [PMID: 38329474 PMCID: PMC10945523 DOI: 10.7554/elife.90799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024] Open
Abstract
Synaptic vesicles dock and fuse at the presynaptic active zone (AZ), the specialized site for transmitter release. AZ proteins play multiple roles such as recruitment of Ca2+ channels as well as synaptic vesicle docking, priming, and fusion. However, the precise role of each AZ protein type remains unknown. In order to dissect the role of RIM-BP2 at mammalian cortical synapses having low release probability, we applied direct electrophysiological recording and super-resolution imaging to hippocampal mossy fiber terminals of RIM-BP2 knockout (KO) mice. By using direct presynaptic recording, we found the reduced Ca2+ currents. The measurements of excitatory postsynaptic currents (EPSCs) and presynaptic capacitance suggested that the initial release probability was lowered because of the reduced Ca2+ influx and impaired fusion competence in RIM-BP2 KO. Nevertheless, larger Ca2+ influx restored release partially. Consistent with presynaptic recording, STED microscopy suggested less abundance of P/Q-type Ca2+ channels at AZs deficient in RIM-BP2. Our results suggest that the RIM-BP2 regulates both Ca2+ channel abundance and transmitter release at mossy fiber synapses.
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Affiliation(s)
- Rinako Miyano
- Graduate School of Brain Science, Doshisha UniversityKyotoJapan
| | - Hirokazu Sakamoto
- Department of Pharmacology, Graduate School of Medicine, The University of TokyoBunkyo-kuJapan
| | - Kenzo Hirose
- Department of Pharmacology, Graduate School of Medicine, The University of TokyoBunkyo-kuJapan
- International Research Center for Neurointelligence (WPI-IRCN), The University of TokyoBunkyo-kuJapan
| | - Takeshi Sakaba
- Graduate School of Brain Science, Doshisha UniversityKyotoJapan
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18
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Ragozzino FJ, Karatsoreos IN, Peters JH. Principles of synaptic encoding of brainstem circadian rhythms. Exp Physiol 2024. [PMID: 38308846 DOI: 10.1113/ep090867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 01/16/2024] [Indexed: 02/05/2024]
Abstract
Circadian regulation of autonomic tone and reflex pathways pairs physiological processes with the daily light cycle. However, the underlying mechanisms mediating these changes on autonomic neurocircuitry are only beginning to be understood. The brainstem nucleus of the solitary tract (NTS) and adjacent nuclei, including the area postrema and dorsal motor nucleus of the vagus, are key candidates for rhythmic control of some aspects of the autonomic nervous system. Recent findings have contributed to a working model of circadian regulation in the brainstem which manifests from the transcriptional, to synaptic, to circuit levels of organization. Vagal afferent neurons and the NTS possess rhythmic clock gene expression, rhythmic action potential firing, and our recent findings demonstrate rhythmic spontaneous glutamate release. In addition, postsynaptic conductances also vary across the day producing subtle changes in membrane depolarization which govern synaptic efficacy. Together these coordinated pre- and postsynaptic changes provide nuanced control of synaptic transmission across the day to tune the sensitivity of primary afferent input and likely govern reflex output. Further, given the important role for the brainstem in integrating cues such as feeding, cardiovascular function and temperature, it may also be an underappreciated locus in mediating the effects of such non-photic entraining cues. This short review focuses on the neurophysiological principles that govern NTS synaptic transmission and how circadian rhythms impacted them across the day.
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Affiliation(s)
- Forrest J Ragozzino
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - Ilia N Karatsoreos
- Department of Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - James H Peters
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
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19
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Xu J, Esser V, Gołębiowska-Mendroch K, Bolembach AA, Rizo J. Control of Munc13-1 Activity by Autoinhibitory Interactions Involving the Variable N-terminal Region. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.24.577102. [PMID: 38328168 PMCID: PMC10849727 DOI: 10.1101/2024.01.24.577102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Regulation of neurotransmitter release during presynaptic plasticity underlies varied forms of information processing in the brain. Munc13s play essential roles in release via their conserved C-terminal region, which contains a MUN domain involved SNARE complex assembly, and control multiple presynaptic plasticity processes. Munc13s also have a variable N-terminal region, which in Munc13-1 includes a calmodulin binding (CaMb) domain involved in short-term plasticity and a C2A domain that forms an inhibitory homodimer. The C2A domain is activated by forming a heterodimer with the zinc-finger domain of αRIMs, providing a link to αRIM-dependent short- and long-term plasticity. However, it is unknown how the functions of the N- and C-terminal regions are integrated, in part because of the difficulty of purifying Munc13-1 fragments containing both regions. We describe for the first time the purification of a Munc13-1 fragment spanning its entire sequence except for a flexible region between the C2A and CaMb domains. We show that this fragment is much less active than the Munc13-1 C-terminal region in liposome fusion assays and that its activity is strongly enhanced by the RIM2α zinc-finger domain together with calmodulin. NMR experiments show that the C2A and CaMb domains bind to the MUN domain and that these interactions are relieved by the RIM2α ZF domain and calmodulin, respectively. These results suggest a model whereby Munc13-1 activity in promoting SNARE complex assembly and neurotransmitter release are inhibited by interactions of the C2A and CaMb domains with the MUN domain that are relieved by αRIMs and calmodulin.
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Affiliation(s)
- Junjie Xu
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Victoria Esser
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Katarzyna Gołębiowska-Mendroch
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Current address: Jagiellonian University, Faculty of Chemistry, Department of Organic Chemistry, Gronostajowa 2, 30-387, Krakow, Poland
| | - Agnieszka A Bolembach
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Current address: Dioscuri Centre for RNA-Protein Interactions in Human Health and Disease, International Institute of Molecular and Cell Biology in Warsaw, 4 Ks. Trojdena Street, 02-109 Warsaw, Poland
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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20
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Silva M, Tran V, Marty A. A maximum of two readily releasable vesicles per docking site at a cerebellar single active zone synapse. eLife 2024; 12:RP91087. [PMID: 38180320 PMCID: PMC10963025 DOI: 10.7554/elife.91087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024] Open
Abstract
Recent research suggests that in central mammalian synapses, active zones contain several docking sites acting in parallel. Before release, one or several synaptic vesicles (SVs) are thought to bind to each docking site, forming the readily releasable pool (RRP). Determining the RRP size per docking site has important implications for short-term synaptic plasticity. Here, using mouse cerebellar slices, we take advantage of recently developed methods to count the number of released SVs at single glutamatergic synapses in response to trains of action potentials (APs). In each recording, the number of docking sites was determined by fitting with a binomial model the number of released SVs in response to individual APs. After normalization with respect to the number of docking sites, the summed number of released SVs following a train of APs was used to estimate of the RRP size per docking site. To improve this estimate, various steps were taken to maximize the release probability of docked SVs, the occupancy of docking sites, as well as the extent of synaptic depression. Under these conditions, the RRP size reached a maximum value close to two SVs per docking site. The results indicate that each docking site contains two distinct SV-binding sites that can simultaneously accommodate up to one SV each. They further suggest that under special experimental conditions, as both sites are close to full occupancy, a maximal RRP size of two SVs per docking site can be reached. More generally, the results validate a sequential two-step docking model previously proposed at this preparation.
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Affiliation(s)
- Melissa Silva
- Université Paris Cité, SPPIN-Saints Pères Paris Institute for the Neurosciences, CNRSParisFrance
| | - Van Tran
- Université Paris Cité, SPPIN-Saints Pères Paris Institute for the Neurosciences, CNRSParisFrance
| | - Alain Marty
- Université Paris Cité, SPPIN-Saints Pères Paris Institute for the Neurosciences, CNRSParisFrance
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21
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Neher E. Interpretation of presynaptic phenotypes of synaptic plasticity in terms of a two-step priming process. J Gen Physiol 2024; 156:e202313454. [PMID: 38112713 PMCID: PMC10730358 DOI: 10.1085/jgp.202313454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023] Open
Abstract
Studies on synaptic proteins involved in neurotransmitter release often aim at distinguishing between their roles in vesicle priming (the docking of synaptic vesicles to the plasma membrane and the assembly of a release machinery) as opposed to the process of vesicle fusion. This has traditionally been done by estimating two parameters, the size of the pool of fusion-competent vesicles (the readily releasable pool, RRP) and the probability that such vesicles are released by an action potential, with the aim of determining how these parameters are affected by molecular perturbations. Here, it is argued that the assumption of a homogeneous RRP may be too simplistic and may blur the distinction between vesicle priming and fusion. Rather, considering priming as a dynamic and reversible multistep process allows alternative interpretations of mutagenesis-induced changes in synaptic transmission and suggests mechanisms for variability in synaptic strength and short-term plasticity among synapses, as well as for interactions between short- and long-term plasticity. In many cases, assigned roles of proteins or causes for observed phenotypes are shifted from fusion- to priming-related when considering multistep priming. Activity-dependent enhancement of priming is an essential element in this alternative view and its variation among synapse types can explain why some synapses show depression and others show facilitation at low to intermediate stimulation frequencies. Multistep priming also suggests a mechanism for frequency invariance of steady-state release, which can be observed in some synapses involved in sensory processing.
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Affiliation(s)
- Erwin Neher
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
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22
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Mrestani A, Dannhäuser S, Pauli M, Kollmannsberger P, Hübsch M, Morris L, Langenhan T, Heckmann M, Paul MM. Nanoscaled RIM clustering at presynaptic active zones revealed by endogenous tagging. Life Sci Alliance 2023; 6:e202302021. [PMID: 37696575 PMCID: PMC10494931 DOI: 10.26508/lsa.202302021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 08/27/2023] [Accepted: 08/28/2023] [Indexed: 09/13/2023] Open
Abstract
Chemical synaptic transmission involves neurotransmitter release from presynaptic active zones (AZs). The AZ protein Rab-3-interacting molecule (RIM) is important for normal Ca2+-triggered release. However, its precise localization within AZs of the glutamatergic neuromuscular junctions of Drosophila melanogaster remains elusive. We used CRISPR/Cas9-assisted genome engineering of the rim locus to incorporate small epitope tags for targeted super-resolution imaging. A V5-tag, derived from simian virus 5, and an HA-tag, derived from human influenza virus, were N-terminally fused to the RIM Zinc finger. Whereas both variants are expressed in co-localization with the core AZ scaffold Bruchpilot, electrophysiological characterization reveals that AP-evoked synaptic release is disturbed in rimV5-Znf but not in rimHA-Znf In addition, rimHA-Znf synapses show intact presynaptic homeostatic potentiation. Combining super-resolution localization microscopy and hierarchical clustering, we detect ∼10 RIMHA-Znf subclusters with ∼13 nm diameter per AZ that are compacted and increased in numbers in presynaptic homeostatic potentiation.
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Affiliation(s)
- Achmed Mrestani
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- Department of Neurology, Leipzig University Medical Center, Leipzig, Germany
- Division of General Biochemistry, Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Sven Dannhäuser
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Martin Pauli
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | | | - Martha Hübsch
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Lydia Morris
- Division of General Biochemistry, Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Tobias Langenhan
- Division of General Biochemistry, Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Manfred Heckmann
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Mila M Paul
- https://ror.org/00fbnyb24 Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- https://ror.org/03pvr2g57 Department of Orthopedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, Würzburg, Germany
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23
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Weichard I, Taschenberger H, Gsell F, Bornschein G, Ritzau-Jost A, Schmidt H, Kittel RJ, Eilers J, Neher E, Hallermann S, Nerlich J. Fully-primed slowly-recovering vesicles mediate presynaptic LTP at neocortical neurons. Proc Natl Acad Sci U S A 2023; 120:e2305460120. [PMID: 37856547 PMCID: PMC10614622 DOI: 10.1073/pnas.2305460120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 08/26/2023] [Indexed: 10/21/2023] Open
Abstract
Pre- and postsynaptic forms of long-term potentiation (LTP) are candidate synaptic mechanisms underlying learning and memory. At layer 5 pyramidal neurons, LTP increases the initial synaptic strength but also short-term depression during high-frequency transmission. This classical form of presynaptic LTP has been referred to as redistribution of synaptic efficacy. However, the underlying mechanisms remain unclear. We therefore performed whole-cell recordings from layer 5 pyramidal neurons in acute cortical slices of rats and analyzed presynaptic function before and after LTP induction by paired pre- and postsynaptic neuronal activity. LTP was successfully induced in about half of the synaptic connections tested and resulted in increased synaptic short-term depression during high-frequency transmission and a decelerated recovery from short-term depression due to an increased fraction of a slow recovery component. Analysis with a recently established sequential two-step vesicle priming model indicates an increase in the abundance of fully-primed and slowly-recovering vesicles. A systematic analysis of short-term plasticity and synapse-to-synapse variability of synaptic strength at various types of synapses revealed that stronger synapses generally recover more slowly from synaptic short-term depression. Finally, pharmacological stimulation of the cyclic adenosine monophosphate and diacylglycerol signaling pathways, which are both known to promote synaptic vesicle priming, mimicked LTP and slowed the recovery from short-term depression. Our data thus demonstrate that LTP at layer 5 pyramidal neurons increases synaptic strength primarily by enlarging a subpool of fully-primed slowly-recovering vesicles.
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Affiliation(s)
- Iron Weichard
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig04103, Germany
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37075, Germany
| | - Felix Gsell
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig04103, Germany
| | - Grit Bornschein
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig04103, Germany
| | - Andreas Ritzau-Jost
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig04103, Germany
| | - Hartmut Schmidt
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig04103, Germany
| | - Robert J. Kittel
- Department of Animal Physiology, Institute of Biology, Leipzig University, Leipzig04103, Germany
| | - Jens Eilers
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig04103, Germany
| | - Erwin Neher
- Emeritus Laboratory of Membrane Biophysics, Max Planck Institute for Multidisciplinary Sciences, Göttingen37070, Germany
- Cluster of Excellence “Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells”, University of Göttingen, Göttingen37073, Germany
| | - Stefan Hallermann
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig04103, Germany
| | - Jana Nerlich
- Faculty of Medicine, Carl-Ludwig-Institute for Physiology, Leipzig University, Leipzig04103, Germany
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24
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Rothman JE, Grushin K, Bera M, Pincet F. Turbocharging synaptic transmission. FEBS Lett 2023; 597:2233-2249. [PMID: 37643878 DOI: 10.1002/1873-3468.14718] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 07/07/2023] [Accepted: 07/11/2023] [Indexed: 08/31/2023]
Abstract
Evidence from biochemistry, genetics, and electron microscopy strongly supports the idea that a ring of Synaptotagmin is central to the clamping and release of synaptic vesicles (SVs) for synchronous neurotransmission. Recent direct measurements in cell-free systems suggest there are 12 SNAREpins in each ready-release vesicle, consisting of six peripheral and six central SNAREpins. The six central SNAREpins are directly bound to the Synaptotagmin ring, are directly released by Ca++ , and they initially open the fusion pore. The six peripheral SNAREpins are indirectly bound to the ring, each linked to a central SNAREpin by a bridging molecule of Complexin. We suggest that the primary role of peripheral SNAREpins is to provide additional force to 'turbocharge' neurotransmitter release, explaining how it can occur much faster than other forms of membrane fusion. The SV protein Synaptophysin forms hexamers that bear two copies of the v-SNARE VAMP at each vertex, one likely assembling into a peripheral SNAREpin and the other into a central SNAREpin.
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Affiliation(s)
- James E Rothman
- Nanobiology Institute and Department of Cell Biology, Yale University, New Haven, CT, USA
| | - Kirill Grushin
- Nanobiology Institute and Department of Cell Biology, Yale University, New Haven, CT, USA
| | - Manindra Bera
- Nanobiology Institute and Department of Cell Biology, Yale University, New Haven, CT, USA
| | - Frederic Pincet
- Nanobiology Institute and Department of Cell Biology, Yale University, New Haven, CT, USA
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, Paris, France
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25
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Ogunmowo T, Hoffmann C, Pepper R, Wang H, Gowrisankaran S, Ho A, Raychaudhuri S, Cooper BH, Milosevic I, Milovanovic D, Watanabe S. Intersectin and Endophilin condensates prime synaptic vesicles for release site replenishment. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.22.554276. [PMID: 37662300 PMCID: PMC10473601 DOI: 10.1101/2023.08.22.554276] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Neurotransmitter is released from dedicated sites of synaptic vesicle fusion within a synapse. Following fusion, the vacated sites are replenished immediately by new vesicles for subsequent neurotransmission. These replacement vesicles are assumed to be located near release sites and used by chance. Here, we find that replacement vesicles are clustered around this region by Intersectin-1. Specifically, Intersectin-1 forms dynamic molecular condensates with Endophilin A1 near release sites and sequesters vesicles around this region. In the absence of Intersectin-1, vesicles within 20 nm of the plasma membrane are reduced, and consequently, vacated sites cannot be replenished rapidly, leading to depression of synaptic transmission. Similarly, mutations in Intersectin-1 that disrupt Endophilin A1 binding result in similar phenotypes. However, in the absence of Endophilin, this replacement pool of vesicles is available but cannot be accessed, suggesting that Endophilin A1 is needed to mobilize these vesicles. Thus, our work describes a distinct physical region within a synapse where replacement vesicles are harbored for release site replenishment.
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Affiliation(s)
- Tyler Ogunmowo
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
| | - Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Renee Pepper
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
| | - Han Wang
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | | | - Annie Ho
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
| | - Sumana Raychaudhuri
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
| | - Benjamin H. Cooper
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Ira Milosevic
- Multidisciplinary Institute of Ageing, University of Coimbra, Coimbra, Portugal
- Nuffield Department of Medicine, Wellcome Centre for Human Genetics, NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
- Einstein Center for Neuroscience, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD USA
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26
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Fukaya R, Miyano R, Hirai H, Sakaba T. Mechanistic insights into cAMP-mediated presynaptic potentiation at hippocampal mossy fiber synapses. Front Cell Neurosci 2023; 17:1237589. [PMID: 37519634 PMCID: PMC10372368 DOI: 10.3389/fncel.2023.1237589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 06/30/2023] [Indexed: 08/01/2023] Open
Abstract
Presynaptic plasticity is an activity-dependent change in the neurotransmitter release and plays a key role in dynamic modulation of synaptic strength. Particularly, presynaptic potentiation mediated by cyclic adenosine monophosphate (cAMP) is widely seen across the animals and thought to contribute to learning and memory. Hippocampal mossy fiber-CA3 pyramidal cell synapses have been used as a model because of robust presynaptic potentiation in short- and long-term forms. Moreover, direct presynaptic recordings from large mossy fiber terminals allow one to dissect the potentiation mechanisms. Recently, super-resolution microscopy and flash-and-freeze electron microscopy have revealed the localizations of release site molecules and synaptic vesicles during the potentiation at a nanoscale, identifying the molecular mechanisms of the potentiation. Incorporating these growing knowledges, we try to present plausible mechanisms underlying the cAMP-mediated presynaptic potentiation.
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Affiliation(s)
- Ryota Fukaya
- Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - Rinako Miyano
- Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Himawari Hirai
- Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Takeshi Sakaba
- Graduate School of Brain Science, Doshisha University, Kyoto, Japan
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27
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Jusyte M, Blaum N, Böhme MA, Berns MMM, Bonard AE, Vámosi ÁB, Pushpalatha KV, Kobbersmed JRL, Walter AM. Unc13A dynamically stabilizes vesicle priming at synaptic release sites for short-term facilitation and homeostatic potentiation. Cell Rep 2023; 42:112541. [PMID: 37243591 DOI: 10.1016/j.celrep.2023.112541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 03/10/2023] [Accepted: 05/03/2023] [Indexed: 05/29/2023] Open
Abstract
Presynaptic plasticity adjusts neurotransmitter (NT) liberation. Short-term facilitation (STF) tunes synapses to millisecond repetitive activation, while presynaptic homeostatic potentiation (PHP) of NT release stabilizes transmission over minutes. Despite different timescales of STF and PHP, our analysis of Drosophila neuromuscular junctions reveals functional overlap and shared molecular dependence on the release-site protein Unc13A. Mutating Unc13A's calmodulin binding domain (CaM-domain) increases baseline transmission while blocking STF and PHP. Mathematical modeling suggests that Ca2+/calmodulin/Unc13A interaction plastically stabilizes vesicle priming at release sites and that CaM-domain mutation causes constitutive stabilization, thereby blocking plasticity. Labeling the functionally essential Unc13A MUN domain reveals higher STED microscopy signals closer to release sites following CaM-domain mutation. Acute phorbol ester treatment similarly enhances NT release and blocks STF/PHP in synapses expressing wild-type Unc13A, while CaM-domain mutation occludes this, indicating common downstream effects. Thus, Unc13A regulatory domains integrate signals across timescales to switch release-site participation for synaptic plasticity.
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Affiliation(s)
- Meida Jusyte
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Einstein Center for Neurosciences Berlin, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Natalie Blaum
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Mathias A Böhme
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Manon M M Berns
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Alix E Bonard
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Ábel B Vámosi
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | | | - Janus R L Kobbersmed
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark; Center of Functionally Integrative Neuroscience, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Alexander M Walter
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Einstein Center for Neurosciences Berlin, Charité Universitätsmedizin Berlin, Berlin, Germany; Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.
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28
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Papantoniou C, Laugks U, Betzin J, Capitanio C, Ferrero JJ, Sánchez-Prieto J, Schoch S, Brose N, Baumeister W, Cooper BH, Imig C, Lučić V. Munc13- and SNAP25-dependent molecular bridges play a key role in synaptic vesicle priming. SCIENCE ADVANCES 2023; 9:eadf6222. [PMID: 37343100 DOI: 10.1126/sciadv.adf6222] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 05/17/2023] [Indexed: 06/23/2023]
Abstract
Synaptic vesicle tethering, priming, and neurotransmitter release require a coordinated action of multiple protein complexes. While physiological experiments, interaction data, and structural studies of purified systems were essential for our understanding of the function of the individual complexes involved, they cannot resolve how the actions of individual complexes integrate. We used cryo-electron tomography to simultaneously image multiple presynaptic protein complexes and lipids at molecular resolution in their native composition, conformation, and environment. Our detailed morphological characterization suggests that sequential synaptic vesicle states precede neurotransmitter release, where Munc13-comprising bridges localize vesicles <10 nanometers and soluble N-ethylmaleimide-sensitive factor attachment protein 25-comprising bridges <5 nanometers from the plasma membrane, the latter constituting a molecularly primed state. Munc13 activation supports the transition to the primed state via vesicle bridges to plasma membrane (tethers), while protein kinase C promotes the same transition by reducing vesicle interlinking. These findings exemplify a cellular function performed by an extended assembly comprising multiple molecularly diverse complexes.
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Affiliation(s)
- Christos Papantoniou
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Ulrike Laugks
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Julia Betzin
- Department of Neuropathology, University Hospital of Bonn, 53127 Bonn, Germany
| | - Cristina Capitanio
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - José Javier Ferrero
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, and Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, 28040 Madrid, Spain
| | - José Sánchez-Prieto
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, and Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, 28040 Madrid, Spain
| | - Susanne Schoch
- Department of Neuropathology, University Hospital of Bonn, 53127 Bonn, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Multidisciplinary Sciences, City Campus, 37075 Göttingen, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Benjamin H Cooper
- Department of Molecular Neurobiology, Max Planck Institute of Multidisciplinary Sciences, City Campus, 37075 Göttingen, Germany
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Multidisciplinary Sciences, City Campus, 37075 Göttingen, Germany
- Department of Neuroscience, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Vladan Lučić
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
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29
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Wender M, Bornschein G, Brachtendorf S, Hallermann S, Eilers J, Schmidt H. Ca v2.2 Channels Sustain Vesicle Recruitment at a Mature Glutamatergic Synapse. J Neurosci 2023; 43:4005-4018. [PMID: 37185239 PMCID: PMC10255130 DOI: 10.1523/jneurosci.1279-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 04/06/2023] [Accepted: 04/08/2023] [Indexed: 05/17/2023] Open
Abstract
The composition of voltage-gated Ca2+ channel (Cav) subtypes that gate action potential (AP)-evoked release changes during the development of mammalian CNS synapses. Cav2.2 and Cav2.3 lose their function in gating-evoked release during postnatal synapse maturation. In mature boutons, Cav2.1 currents provide the almost exclusive trigger for evoked release, and Cav2.3 currents are required for the induction of presynaptic long-term potentiation. However, the functional significance of Cav2.2 remained elusive in mature boutons, although they remain present at active zones and continue contributing significantly to presynaptic Ca2+ influx. Here, we addressed the functional significance of Cav2.2 and Cav2.3 at mature parallel-fiber (PF) to Purkinje neuron synapses of mice of either sex. These synapses are known to exhibit the corresponding developmental Cav subtype changes in gating release. We addressed two hypotheses, namely that Cav2.2 and Cav2.3 are involved in triggering spontaneous glutamate release and that they are engaged in vesicle recruitment during repetitive evoked release. We found that spontaneous miniature release is Ca2+ dependent. However, experiments with Cav subtype-specific blockers excluded the spontaneous opening of Cavs as the Ca2+ source for spontaneous glutamate release. Thus, neither Cav2.2 nor Cav2.3 controls spontaneous release from PF boutons. Furthermore, vesicle recruitment during brief bursts of APs was also independent of Ca2+ influx through Cav2.2 and Cav2.3. However, Cav2.2, but not Cav2.3, currents significantly boosted vesicle recruitment during sustained high-frequency synaptic transmission. Thus, in mature PF boutons Cav2.2 channels are specifically required to sustain synaptic transmission during prolonged neuronal activity.SIGNIFICANCE STATEMENT At young CNS synapses, action potential-evoked release is gated via three subtypes of voltage-gated Ca2+ channels: Cav2.1, Cav2.2, and Cav2.3. During postnatal maturation, Cav2.2 and Cav2.3 lose their function in gating evoked release, such that at mature synapses Cav2.1 provides the almost exclusive source for triggering evoked release. Cav2.3 currents are required for the induction of presynaptic long-term potentiation. However, the function of the still abundant Cav2.2 in mature boutons remained largely elusive. Here, we studied mature cerebellar parallel-fiber synapses and found that Cav2.2 does not control spontaneous release. However, Ca2+ influx through Cav2.2 significantly boosted vesicle recruitment during trains of action potentials. Thus, Cav2.2 in mature parallel-fiber boutons participate in sustaining synaptic transmission during prolonged activity.
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Affiliation(s)
- Magdalena Wender
- Carl Ludwig Institute for Physiology, Medical Faculty, Leipzig University, 04103 Leipzig, Germany
| | - Grit Bornschein
- Carl Ludwig Institute for Physiology, Medical Faculty, Leipzig University, 04103 Leipzig, Germany
| | - Simone Brachtendorf
- Carl Ludwig Institute for Physiology, Medical Faculty, Leipzig University, 04103 Leipzig, Germany
| | - Stefan Hallermann
- Carl Ludwig Institute for Physiology, Medical Faculty, Leipzig University, 04103 Leipzig, Germany
| | - Jens Eilers
- Carl Ludwig Institute for Physiology, Medical Faculty, Leipzig University, 04103 Leipzig, Germany
| | - Hartmut Schmidt
- Carl Ludwig Institute for Physiology, Medical Faculty, Leipzig University, 04103 Leipzig, Germany
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Rozenfeld E, Ehmann N, Manoim JE, Kittel RJ, Parnas M. Homeostatic synaptic plasticity rescues neural coding reliability. Nat Commun 2023; 14:2993. [PMID: 37225688 DOI: 10.1038/s41467-023-38575-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 05/08/2023] [Indexed: 05/26/2023] Open
Abstract
To survive, animals must recognize reoccurring stimuli. This necessitates a reliable stimulus representation by the neural code. While synaptic transmission underlies the propagation of neural codes, it is unclear how synaptic plasticity can maintain coding reliability. By studying the olfactory system of Drosophila melanogaster, we aimed to obtain a deeper mechanistic understanding of how synaptic function shapes neural coding in the live, behaving animal. We show that the properties of the active zone (AZ), the presynaptic site of neurotransmitter release, are critical for generating a reliable neural code. Reducing neurotransmitter release probability of olfactory sensory neurons disrupts both neural coding and behavioral reliability. Strikingly, a target-specific homeostatic increase of AZ numbers rescues these defects within a day. These findings demonstrate an important role for synaptic plasticity in maintaining neural coding reliability and are of pathophysiological interest by uncovering an elegant mechanism through which the neural circuitry can counterbalance perturbations.
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Affiliation(s)
- Eyal Rozenfeld
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Nadine Ehmann
- Department of Animal Physiology, Institute of Biology, Leipzig University, 04103, Leipzig, Germany
| | - Julia E Manoim
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Robert J Kittel
- Department of Animal Physiology, Institute of Biology, Leipzig University, 04103, Leipzig, Germany.
| | - Moshe Parnas
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel.
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, 69978, Israel.
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31
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Chang HF, Schirra C, Pattu V, Krause E, Becherer U. Lytic granule exocytosis at immune synapses: lessons from neuronal synapses. Front Immunol 2023; 14:1177670. [PMID: 37275872 PMCID: PMC10233144 DOI: 10.3389/fimmu.2023.1177670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/09/2023] [Indexed: 06/07/2023] Open
Abstract
Regulated exocytosis is a central mechanism of cellular communication. It is not only the basis for neurotransmission and hormone release, but also plays an important role in the immune system for the release of cytokines and cytotoxic molecules. In cytotoxic T lymphocytes (CTLs), the formation of the immunological synapse is required for the delivery of the cytotoxic substances such as granzymes and perforin, which are stored in lytic granules and released via exocytosis. The molecular mechanisms of their fusion with the plasma membrane are only partially understood. In this review, we discuss the molecular players involved in the regulated exocytosis of CTL, highlighting the parallels and differences to neuronal synaptic transmission. Additionally, we examine the strengths and weaknesses of both systems to study exocytosis.
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Martín R, Suárez-Pinilla AS, García-Font N, Laguna-Luque ML, López-Ramos JC, Oset-Gasque MJ, Gruart A, Delgado-García JM, Torres M, Sánchez-Prieto J. The activation of mGluR4 rescues parallel fiber synaptic transmission and LTP, motor learning and social behavior in a mouse model of Fragile X Syndrome. Mol Autism 2023; 14:14. [PMID: 37029391 PMCID: PMC10082511 DOI: 10.1186/s13229-023-00547-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 04/03/2023] [Indexed: 04/09/2023] Open
Abstract
BACKGROUND Fragile X syndrome (FXS), the most common inherited intellectual disability, is caused by the loss of expression of the Fragile X Messenger Ribonucleoprotein (FMRP). FMRP is an RNA-binding protein that negatively regulates the expression of many postsynaptic as well as presynaptic proteins involved in action potential properties, calcium homeostasis and neurotransmitter release. FXS patients and mice lacking FMRP suffer from multiple behavioral alterations, including deficits in motor learning for which there is currently no specific treatment. METHODS We performed electron microscopy, whole-cell patch-clamp electrophysiology and behavioral experiments to characterise the synaptic mechanisms underlying the motor learning deficits observed in Fmr1KO mice and the therapeutic potential of positive allosteric modulator of mGluR4. RESULTS We found that enhanced synaptic vesicle docking of cerebellar parallel fiber to Purkinje cell Fmr1KO synapses was associated with enhanced asynchronous release, which not only prevents further potentiation, but it also compromises presynaptic parallel fiber long-term potentiation (PF-LTP) mediated by β adrenergic receptors. A reduction in extracellular Ca2+ concentration restored the readily releasable pool (RRP) size, basal synaptic transmission, β adrenergic receptor-mediated potentiation, and PF-LTP. Interestingly, VU 0155041, a selective positive allosteric modulator of mGluR4, also restored both the RRP size and PF-LTP in mice of either sex. Moreover, when injected into Fmr1KO male mice, VU 0155041 improved motor learning in skilled reaching, classical eyeblink conditioning and vestibuloocular reflex (VOR) tests, as well as the social behavior alterations of these mice. LIMITATIONS We cannot rule out that the activation of mGluR4s via systemic administration of VU0155041 can also affect other brain regions. Further studies are needed to stablish the effect of a specific activation of mGluR4 in cerebellar granule cells. CONCLUSIONS Our study shows that an increase in synaptic vesicles, SV, docking may cause the loss of PF-LTP and motor learning and social deficits of Fmr1KO mice and that the reversal of these changes by pharmacological activation of mGluR4 may offer therapeutic relief for motor learning and social deficits in FXS.
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Affiliation(s)
- Ricardo Martín
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, Instituto Universitario de Investigación en Neuroquímica, 28040, Madrid, Spain.
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, 28040, Madrid, Spain.
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense, 28040, Madrid, Spain.
| | - Alberto Samuel Suárez-Pinilla
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, Instituto Universitario de Investigación en Neuroquímica, 28040, Madrid, Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, 28040, Madrid, Spain
| | - Nuria García-Font
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, Instituto Universitario de Investigación en Neuroquímica, 28040, Madrid, Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, 28040, Madrid, Spain
- Centre for Discovery Brain Sciences and Simon Initiative for Developing Brain, University of Edinburgh, Edinburgh, EH89JZ, UK
| | | | - Juan C López-Ramos
- Division de Neurociencias, Universidad Pablo de Olavide, 41013, Sevilla, Spain
| | - María Jesús Oset-Gasque
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, 28040, Madrid, Spain
- Departamento de Bioquímica, Facultad de Farmacia, Universidad Complutense, Instituto Universitario Investigación en Neuroquímica, 28040, Madrid, Spain
| | - Agnes Gruart
- Division de Neurociencias, Universidad Pablo de Olavide, 41013, Sevilla, Spain
| | | | - Magdalena Torres
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, Instituto Universitario de Investigación en Neuroquímica, 28040, Madrid, Spain
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, 28040, Madrid, Spain
| | - José Sánchez-Prieto
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, Instituto Universitario de Investigación en Neuroquímica, 28040, Madrid, Spain.
- Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, 28040, Madrid, Spain.
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Maneu V, Borges R, Gandía L, García AG. Forty years of the adrenal chromaffin cell through ISCCB meetings around the world. Pflugers Arch 2023; 475:667-690. [PMID: 36884064 DOI: 10.1007/s00424-023-02793-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/20/2023] [Accepted: 01/28/2023] [Indexed: 03/09/2023]
Abstract
This historical review focuses on the evolution of the knowledge accumulated during the last two centuries on the biology of the adrenal medulla gland and its chromaffin cells (CCs). The review emerged in the context of a series of meetings that started on the Spanish island of Ibiza in 1982 with the name of the International Symposium on Chromaffin Cell Biology (ISCCB). Hence, the review is divided into two periods namely, before 1982 and from this year to 2022, when the 21st ISCCB meeting was just held in Hamburg, Germany. The first historical period extends back to 1852 when Albert Kölliker first described the fine structure and function of the adrenal medulla. Subsequently, the adrenal staining with chromate salts identified the CCs; this was followed by the establishment of the embryological origin of the adrenal medulla, and the identification of adrenaline-storing vesicles. By the end of the nineteenth century, the basic morphology, histochemistry, and embryology of the adrenal gland were known. The twentieth century began with breakthrough findings namely, the experiment of Elliott suggesting that adrenaline was the sympathetic neurotransmitter, the isolation of pure adrenaline, and the deciphering of its molecular structure and chemical synthesis in the laboratory. In the 1950s, Blaschko isolated the catecholamine-storing vesicles from adrenal medullary extracts. This switched the interest in CCs as models of sympathetic neurons with an explosion of studies concerning their functions, i.e., uptake of catecholamines by chromaffin vesicles through a specific coupled transport system; the identification of several vesicle components in addition to catecholamines including chromogranins, ATP, opioids, and other neuropeptides; the calcium-dependence of the release of catecholamines; the underlying mechanism of exocytosis of this release, as indicated by the co-release of proteins; the cross-talk between the adrenal cortex and the medulla; and the emission of neurite-like processes by CCs in culture, among other numerous findings. The 1980s began with the introduction of new high-resolution techniques such as patch-clamp, calcium probes, marine toxins-targeting ion channels and receptors, confocal microscopy, or amperometry. In this frame of technological advances at the Ibiza ISCCB meeting in 1982, 11 senior researchers in the field predicted a notable increase in our knowledge in the field of CCs and the adrenal medulla; this cumulative knowledge that occurred in the last 40 years of history of the CC is succinctly described in the second part of this historical review. It deals with cell excitability, ion channel currents, the exocytotic fusion pore, the handling of calcium ions by CCs, the kinetics of exocytosis and endocytosis, the exocytotic machinery, and the life cycle of secretory vesicles. These concepts together with studies on the dynamics of membrane fusion with super-resolution imaging techniques at the single-protein level were extensively reviewed by top scientists in the field at the 21st ISCCB meeting in Hamburg in the summer of 2022; this frontier topic is also briefly reviewed here. Many of the concepts arising from those studies contributed to our present understanding of synaptic transmission. This has been studied in physiological or pathophysiological conditions, in CCs from animal disease models. In conclusion, the lessons we have learned from CC biology as a peripheral model for brain and brain disease pertain more than ever to cutting-edge research in neurobiology. In the 22nd ISCCB meeting in Israel in 2024 that Uri Asheri is organizing, we will have the opportunity of seeing the progress of the questions posed in Ibiza, and on other questions that undoubtedly will arise.
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Affiliation(s)
- Victoria Maneu
- Departamento de Óptica, Farmacología y Anatomía, Universidad de Alicante, Alicante, Spain
| | - Ricardo Borges
- Unidad de Farmacología, Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de La Laguna, Tenerife, Spain
| | - Luis Gandía
- Instituto Fundación Teófilo Hernando, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain
| | - Antonio G García
- Instituto Fundación Teófilo Hernando, Madrid, Spain. .,Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain. .,Facultad de Medicina, Instituto de Investigación Sanitaria del Hospital Universitario La Princesa, Universidad Autónoma de Madrid, Madrid, Spain.
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Mueller BD, Merrill SA, Watanabe S, Liu P, Niu L, Singh A, Maldonado-Catala P, Cherry A, Rich MS, Silva M, Maricq AV, Wang ZW, Jorgensen EM. CaV1 and CaV2 calcium channels mediate the release of distinct pools of synaptic vesicles. eLife 2023; 12:e81407. [PMID: 36820519 PMCID: PMC10023163 DOI: 10.7554/elife.81407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 02/22/2023] [Indexed: 02/24/2023] Open
Abstract
Activation of voltage-gated calcium channels at presynaptic terminals leads to local increases in calcium and the fusion of synaptic vesicles containing neurotransmitter. Presynaptic output is a function of the density of calcium channels, the dynamic properties of the channel, the distance to docked vesicles, and the release probability at the docking site. We demonstrate that at Caenorhabditis elegans neuromuscular junctions two different classes of voltage-gated calcium channels, CaV2 and CaV1, mediate the release of distinct pools of synaptic vesicles. CaV2 channels are concentrated in densely packed clusters ~250 nm in diameter with the active zone proteins Neurexin, α-Liprin, SYDE, ELKS/CAST, RIM-BP, α-Catulin, and MAGI1. CaV2 channels are colocalized with the priming protein UNC-13L and mediate the fusion of vesicles docked within 33 nm of the dense projection. CaV2 activity is amplified by ryanodine receptor release of calcium from internal stores, triggering fusion up to 165 nm from the dense projection. By contrast, CaV1 channels are dispersed in the synaptic varicosity, and are colocalized with UNC-13S. CaV1 and ryanodine receptors are separated by just 40 nm, and vesicle fusion mediated by CaV1 is completely dependent on the ryanodine receptor. Distinct synaptic vesicle pools, released by different calcium channels, could be used to tune the speed, voltage-dependence, and quantal content of neurotransmitter release.
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Affiliation(s)
- Brian D Mueller
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Sean A Merrill
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Shigeki Watanabe
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Ping Liu
- Department of Neuroscience, University of Connecticut Medical SchoolFarmingtonUnited States
| | - Longgang Niu
- Department of Neuroscience, University of Connecticut Medical SchoolFarmingtonUnited States
| | - Anish Singh
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | | | - Alex Cherry
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Matthew S Rich
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Malan Silva
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | | | - Zhao-Wen Wang
- Department of Neuroscience, University of Connecticut Medical SchoolFarmingtonUnited States
| | - Erik M Jorgensen
- Howard Hughes Medical Institute, School of Biological Sciences, University of UtahSalt Lake CityUnited States
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Fukaya R, Hirai H, Sakamoto H, Hashimotodani Y, Hirose K, Sakaba T. Increased vesicle fusion competence underlies long-term potentiation at hippocampal mossy fiber synapses. SCIENCE ADVANCES 2023; 9:eadd3616. [PMID: 36812326 PMCID: PMC9946361 DOI: 10.1126/sciadv.add3616] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 01/23/2023] [Indexed: 06/18/2023]
Abstract
Presynaptic long-term potentiation (LTP) is thought to play an important role in learning and memory. However, the underlying mechanism remains elusive because of the difficulty of direct recording during LTP. Hippocampal mossy fiber synapses exhibit pronounced LTP of transmitter release after tetanic stimulation and have been used as a model of presynaptic LTP. Here, we induced LTP by optogenetic tools and applied direct presynaptic patch-clamp recordings. The action potential waveform and evoked presynaptic Ca2+ currents remained unchanged after LTP induction. Membrane capacitance measurements suggested higher release probability of synaptic vesicles without changing the number of release-ready vesicles after LTP induction. Synaptic vesicle replenishment was also enhanced. Furthermore, stimulated emission depletion microscopy suggested an increase in the numbers of Munc13-1 and RIM1 molecules within active zones. We propose that dynamic changes in the active zone components may be relevant for the increased fusion competence and synaptic vesicle replenishment during LTP.
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Affiliation(s)
- Ryota Fukaya
- Graduate School of Brain Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
- Institute of Biology/Genetics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Himawari Hirai
- Graduate School of Brain Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Hirokazu Sakamoto
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yuki Hashimotodani
- Graduate School of Brain Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
| | - Kenzo Hirose
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takeshi Sakaba
- Graduate School of Brain Science, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan
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Palfreyman MT, West SE, Jorgensen EM. SNARE Proteins in Synaptic Vesicle Fusion. ADVANCES IN NEUROBIOLOGY 2023; 33:63-118. [PMID: 37615864 DOI: 10.1007/978-3-031-34229-5_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Neurotransmitters are stored in small membrane-bound vesicles at synapses; a subset of synaptic vesicles is docked at release sites. Fusion of docked vesicles with the plasma membrane releases neurotransmitters. Membrane fusion at synapses, as well as all trafficking steps of the secretory pathway, is mediated by SNARE proteins. The SNAREs are the minimal fusion machinery. They zipper from N-termini to membrane-anchored C-termini to form a 4-helix bundle that forces the apposed membranes to fuse. At synapses, the SNAREs comprise a single helix from syntaxin and synaptobrevin; SNAP-25 contributes the other two helices to complete the bundle. Unc13 mediates synaptic vesicle docking and converts syntaxin into the permissive "open" configuration. The SM protein, Unc18, is required to initiate and proofread SNARE assembly. The SNAREs are then held in a half-zippered state by synaptotagmin and complexin. Calcium removes the synaptotagmin and complexin block, and the SNAREs drive vesicle fusion. After fusion, NSF and alpha-SNAP unwind the SNAREs and thereby recharge the system for further rounds of fusion. In this chapter, we will describe the discovery of the SNAREs, their relevant structural features, models for their function, and the central role of Unc18. In addition, we will touch upon the regulation of SNARE complex formation by Unc13, complexin, and synaptotagmin.
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Affiliation(s)
- Mark T Palfreyman
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Sam E West
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Erik M Jorgensen
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA.
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López-Murcia FJ, Reim K, Taschenberger H. Complexins: Ubiquitously Expressed Presynaptic Regulators of SNARE-Mediated Synaptic Vesicle Fusion. ADVANCES IN NEUROBIOLOGY 2023; 33:255-285. [PMID: 37615870 DOI: 10.1007/978-3-031-34229-5_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Neurotransmitter release is a spatially and temporally tightly regulated process, which requires assembly and disassembly of SNARE complexes to enable the exocytosis of transmitter-loaded synaptic vesicles (SVs) at presynaptic active zones (AZs). While the requirement for the core SNARE machinery is shared by most membrane fusion processes, SNARE-mediated fusion at AZs is uniquely regulated to allow very rapid Ca2+-triggered SV exocytosis following action potential (AP) arrival. To enable a sub-millisecond time course of AP-triggered SV fusion, synapse-specific accessory SNARE-binding proteins are required in addition to the core fusion machinery. Among the known SNARE regulators specific for Ca2+-triggered SV fusion are complexins, which are almost ubiquitously expressed in neurons. This chapter summarizes the structural features of complexins, models for their molecular interactions with SNAREs, and their roles in SV fusion.
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Affiliation(s)
- Francisco José López-Murcia
- Department of Pathology and Experimental Therapy, Institute of Neurosciences, University of Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.
- Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
| | - Kerstin Reim
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
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Yan C, Jiang J, Yang Y, Geng X, Dong W. The function of VAMP2 in mediating membrane fusion: An overview. Front Mol Neurosci 2022; 15:948160. [PMID: 36618823 PMCID: PMC9816800 DOI: 10.3389/fnmol.2022.948160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Vesicle-associated membrane protein 2 (VAMP2, also known as synaptobrevin-2), encoded by VAMP2 in humans, is a key component of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex. VAMP2 combined with syntaxin-1A (SYX-1A) and synaptosome-associated protein 25 (SNAP-25) produces a force that induces the formation of fusion pores, thereby mediating the fusion of synaptic vesicles and the release of neurotransmitters. VAMP2 is largely unstructured in the absence of interaction partners. Upon interaction with other SNAREs, the structure of VAMP2 stabilizes, resulting in the formation of four structural domains. In this review, we highlight the current knowledge of the roles of the VAMP2 domains and the interaction between VAMP2 and various fusion-related proteins in the presynaptic cytoplasm during the fusion process. Our summary will contribute to a better understanding of the roles of the VAMP2 protein in membrane fusion.
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Affiliation(s)
- Chong Yan
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
| | - Jie Jiang
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
| | - Yuan Yang
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
| | - Xiaoqi Geng
- Department of Neurosurgery, Neurosurgical Clinical Research Center of Sichuan Province, Affiliated Hospital of Southwest Medical University, Luzhou, China,*Correspondence: Xiaoqi Geng,
| | - Wei Dong
- Key Laboratory of Medical Electrophysiology, Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China,Wei Dong,
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Aldahabi M, Balint F, Holderith N, Lorincz A, Reva M, Nusser Z. Different priming states of synaptic vesicles underlie distinct release probabilities at hippocampal excitatory synapses. Neuron 2022; 110:4144-4161.e7. [PMID: 36261033 PMCID: PMC9796815 DOI: 10.1016/j.neuron.2022.09.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/28/2022] [Accepted: 09/27/2022] [Indexed: 12/12/2022]
Abstract
A stunning example of synaptic diversity is the postsynaptic target cell-type-dependent difference in synaptic efficacy in cortical networks. Here, we show that CA1 pyramidal cell (PC) to fast spiking interneuron (FSIN) connections have 10-fold larger release probability (Pv) than those on oriens lacunosum-moleculare (O-LM) interneurons. Freeze-fracture immunolabeling revealed that different nano-topologies and coupling distances between Ca2+ channels and release sites (RSs) are not responsible for the distinct Pv. Although [Ca2+] transients are 40% larger in FSINs innervating boutons, when [Ca2+] entry is matched in the two bouton populations, EPSCs in O-LM cells are still 7-fold smaller. However, application of a phorbol ester analog resulted in a ∼2.5-fold larger augmentation at PC - O-LM compared to PC - FSIN synapses, suggesting incomplete docking or priming of vesicles. Similar densities of docked vesicles rule out distinct RS occupancies and demonstrate that incompletely primed, but docked, vesicles limit the output of PC - O-LM synapses.
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Affiliation(s)
- Mohammad Aldahabi
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary,János Szentágothai School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Flora Balint
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary
| | - Noemi Holderith
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary
| | - Andrea Lorincz
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary
| | - Maria Reva
- Unit of Synapse and Circuit Dynamics, CNRS UMR 3571, Institute Pasteur, Paris, France
| | - Zoltan Nusser
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest 1083, Hungary,Corresponding author
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Dannhäuser S, Mrestani A, Gundelach F, Pauli M, Komma F, Kollmannsberger P, Sauer M, Heckmann M, Paul MM. Endogenous tagging of Unc-13 reveals nanoscale reorganization at active zones during presynaptic homeostatic potentiation. Front Cell Neurosci 2022; 16:1074304. [PMID: 36589286 PMCID: PMC9797049 DOI: 10.3389/fncel.2022.1074304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 11/23/2022] [Indexed: 12/15/2022] Open
Abstract
Introduction Neurotransmitter release at presynaptic active zones (AZs) requires concerted protein interactions within a dense 3D nano-hemisphere. Among the complex protein meshwork the (M)unc-13 family member Unc-13 of Drosophila melanogaster is essential for docking of synaptic vesicles and transmitter release. Methods We employ minos-mediated integration cassette (MiMIC)-based gene editing using GFSTF (EGFP-FlAsH-StrepII-TEV-3xFlag) to endogenously tag all annotated Drosophila Unc-13 isoforms enabling visualization of endogenous Unc-13 expression within the central and peripheral nervous system. Results and discussion Electrophysiological characterization using two-electrode voltage clamp (TEVC) reveals that evoked and spontaneous synaptic transmission remain unaffected in unc-13 GFSTF 3rd instar larvae and acute presynaptic homeostatic potentiation (PHP) can be induced at control levels. Furthermore, multi-color structured-illumination shows precise co-localization of Unc-13GFSTF, Bruchpilot, and GluRIIA-receptor subunits within the synaptic mesoscale. Localization microscopy in combination with HDBSCAN algorithms detect Unc-13GFSTF subclusters that move toward the AZ center during PHP with unaltered Unc-13GFSTF protein levels.
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Affiliation(s)
- Sven Dannhäuser
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Achmed Mrestani
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- Department of Neurology, Leipzig University Medical Center, Leipzig, Germany
- Division of General Biochemistry, Rudolf Schönheimer Institute of Biochemistry, Medical Faculty, Leipzig University, Leipzig, Germany
| | - Florian Gundelach
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- Center of Mental Health, Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Würzburg, Würzburg, Germany
| | - Martin Pauli
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Fabian Komma
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Philip Kollmannsberger
- Center for Computational and Theoretical Biology, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Manfred Heckmann
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Mila M Paul
- Department of Neurophysiology, Institute of Physiology, University of Würzburg, Würzburg, Germany
- Department of Orthopedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, Würzburg, Germany
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Chen X, Li J, Zhang R, Zhang Y, Wang X, Leung EL, Ma L, Wong VKW, Liu L, Neher E, Yu H. Suppression of PD-L1 release from small extracellular vesicles promotes systemic anti-tumor immunity by targeting ORAI1 calcium channels. J Extracell Vesicles 2022; 11:e12279. [PMID: 36482876 PMCID: PMC9732629 DOI: 10.1002/jev2.12279] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/28/2022] [Accepted: 06/01/2022] [Indexed: 12/13/2022] Open
Abstract
Blockade of immune checkpoints as a strategy of cancer cells to overcome the immune response has received ample attention in cancer research recently. In particular, expression of PD-L1 by various cancer cells has become a paradigm in this respect. Delivery of PD-L1 to its site of action occurs either by local diffusion, or else by transport via small extracellular vesicles (sEVs, commonly referred to as exosomes). Many steps of sEVs formation, their packaging with PD-L1 and their release into the extracellular space have been studied in detail. The likely dependence of release on Ca2+ -signaling, however, has received little attention. This is surprising, since the intracellular Ca2+ -concentration is known as a prominent regulator of many secretory processes. Here, we report on the roles of three Ca2+ -dependent proteins in regulating release of PD-L1-containing sEVs, as well as on the growth of tumors in mouse models. We show that sEVs release in cancer cell lines is Ca2+ -dependent and the knockdown of the gene coding the Ca2+ -channel protein ORAI1 reduces Ca2+ -signals and release of sEVs. Consequently, the T cell response is reinvigorated and tumor progression in mouse models is retarded. Furthermore, analysis of protein expression patterns in samples from human cancer tissue shows that the ORAI1 gene is significantly upregulated. Such upregulation is identified as an unfavorable prognostic factor for survival of patients with non-small-cell lung cancer. We show that reduced Ca2+ -signaling after knockdown of ORAI1 gene also compromises the activity of melanophilin and Synaptotagmin-like protein 2, two proteins, which are important for correct localization of secretory organelles within cancer cells and their transport to sites of exocytosis. Thus, the Ca2+ -channel ORAI1 and Ca2+ -dependent proteins of the secretion pathway emerge as important targets for understanding and manipulating immune checkpoint blockade by PD-L1.
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Affiliation(s)
- Xi Chen
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
| | - Jiaqi Li
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
| | - Ren Zhang
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
| | - Yao Zhang
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
| | - Xiaoxuan Wang
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
| | - Elaine Lai‐Han Leung
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
| | - Lijuan Ma
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
| | - Vincent Kam Wai Wong
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
| | - Liang Liu
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
| | - Erwin Neher
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina,Emeritus Laboratory of Membrane BiophysicsMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Haijie Yu
- Dr. Neher's Biophysics Laboratory for Innovative Drug DiscoveryState Key Laboratory of Quality Research in Chinese MedicineMacau University of Science and TechnologyTaipaMacauChina
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42
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Weingarten DJ, Shrestha A, Juda-Nelson K, Kissiwaa SA, Spruston E, Jackman SL. Fast resupply of synaptic vesicles requires synaptotagmin-3. Nature 2022; 611:320-325. [PMID: 36261524 DOI: 10.1038/s41586-022-05337-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 09/12/2022] [Indexed: 01/09/2023]
Abstract
Sustained neuronal activity demands a rapid resupply of synaptic vesicles to maintain reliable synaptic transmission. Such vesicle replenishment is accelerated by submicromolar presynaptic Ca2+ signals by an as-yet unidentified high-affinity Ca2+ sensor1,2. Here we identify synaptotagmin-3 (SYT3)3,4 as that presynaptic high-affinity Ca2+ sensor, which drives vesicle replenishment and short-term synaptic plasticity. Synapses in Syt3 knockout mice exhibited enhanced short-term depression, and recovery from depression was slower and insensitive to presynaptic residual Ca2+. During sustained neuronal firing, SYT3 accelerated vesicle replenishment and increased the size of the readily releasable pool. SYT3 also mediated short-term facilitation under conditions of low release probability and promoted synaptic enhancement together with another high-affinity synaptotagmin, SYT7 (ref. 5). Biophysical modelling predicted that SYT3 mediates both replenishment and facilitation by promoting the transition of loosely docked vesicles to tightly docked, primed states. Our results reveal a crucial role for presynaptic SYT3 in the maintenance of reliable high-frequency synaptic transmission. Moreover, multiple forms of short-term plasticity may converge on a mechanism of reversible, Ca2+-dependent vesicle docking.
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Affiliation(s)
| | - Amita Shrestha
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Kessa Juda-Nelson
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Sarah A Kissiwaa
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Evan Spruston
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Skyler L Jackman
- Vollum Institute, Oregon Health and Science University, Portland, OR, USA.
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43
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Lichter K, Paul MM, Pauli M, Schoch S, Kollmannsberger P, Stigloher C, Heckmann M, Sirén AL. Ultrastructural analysis of wild-type and RIM1α knockout active zones in a large cortical synapse. Cell Rep 2022; 40:111382. [PMID: 36130490 DOI: 10.1016/j.celrep.2022.111382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 06/14/2022] [Accepted: 08/28/2022] [Indexed: 11/18/2022] Open
Abstract
Rab3A-interacting molecule (RIM) is crucial for fast Ca2+-triggered synaptic vesicle (SV) release in presynaptic active zones (AZs). We investigated hippocampal giant mossy fiber bouton (MFB) AZ architecture in 3D using electron tomography of rapid cryo-immobilized acute brain slices in RIM1α-/- and wild-type mice. In RIM1α-/-, AZs are larger with increased synaptic cleft widths and a 3-fold reduced number of tightly docked SVs (0-2 nm). The distance of tightly docked SVs to the AZ center is increased from 110 to 195 nm, and the width of their electron-dense material between outer SV membrane and AZ membrane is reduced. Furthermore, the SV pool in RIM1α-/- is more heterogeneous. Thus, RIM1α, besides its role in tight SV docking, is crucial for synaptic architecture and vesicle pool organization in MFBs.
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Affiliation(s)
- Katharina Lichter
- Department of Neurosurgery, University Hospital of Würzburg, 97080 Würzburg, Germany; Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany; Center of Mental Health, Department of Psychiatry, Psychosomatics and Psychotherapy, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Mila Marie Paul
- Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany; Department of Orthopedic Trauma, Hand, Plastic and Reconstructive Surgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Martin Pauli
- Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany
| | - Susanne Schoch
- Department of Neuropathology and Department of Epileptology, University Hospital Bonn, 53127 Bonn, Germany
| | - Philip Kollmannsberger
- Center for Computational and Theoretical Biology, Julius-Maximilians-University Würzburg, 97074 Würzburg, Germany
| | - Christian Stigloher
- Imaging Core Facility, Biocenter, University of Würzburg, 97074 Würzburg, Germany.
| | - Manfred Heckmann
- Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany.
| | - Anna-Leena Sirén
- Department of Neurosurgery, University Hospital of Würzburg, 97080 Würzburg, Germany; Institute for Physiology, Department of Neurophysiology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany.
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44
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Imoto Y, Raychaudhuri S, Ma Y, Fenske P, Sandoval E, Itoh K, Blumrich EM, Matsubayashi HT, Mamer L, Zarebidaki F, Söhl-Kielczynski B, Trimbuch T, Nayak S, Iwasa JH, Liu J, Wu B, Ha T, Inoue T, Jorgensen EM, Cousin MA, Rosenmund C, Watanabe S. Dynamin is primed at endocytic sites for ultrafast endocytosis. Neuron 2022; 110:2815-2835.e13. [PMID: 35809574 PMCID: PMC9464723 DOI: 10.1016/j.neuron.2022.06.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 03/24/2022] [Accepted: 06/09/2022] [Indexed: 02/06/2023]
Abstract
Dynamin mediates fission of vesicles from the plasma membrane during endocytosis. Typically, dynamin is recruited from the cytosol to endocytic sites, requiring seconds to tens of seconds. However, ultrafast endocytosis in neurons internalizes vesicles as quickly as 50 ms during synaptic vesicle recycling. Here, we demonstrate that Dynamin 1 is pre-recruited to endocytic sites for ultrafast endocytosis. Specifically, Dynamin 1xA, a splice variant of Dynamin 1, interacts with Syndapin 1 to form molecular condensates on the plasma membrane. Single-particle tracking of Dynamin 1xA molecules confirms the liquid-like property of condensates in vivo. When Dynamin 1xA is mutated to disrupt its interaction with Syndapin 1, the condensates do not form, and consequently, ultrafast endocytosis slows down by 100-fold. Mechanistically, Syndapin 1 acts as an adaptor by binding the plasma membrane and stores Dynamin 1xA at endocytic sites. This cache bypasses the recruitment step and accelerates endocytosis at synapses.
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Affiliation(s)
- Yuuta Imoto
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA.
| | - Sumana Raychaudhuri
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Ye Ma
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Pascal Fenske
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Eduardo Sandoval
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kie Itoh
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Eva-Maria Blumrich
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK; The Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK; Simons Initiatives for the Developing Brain, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK
| | - Hideaki T Matsubayashi
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA; The Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Lauren Mamer
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Fereshteh Zarebidaki
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | | | - Thorsten Trimbuch
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Shraddha Nayak
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Janet H Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Jian Liu
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA; Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK
| | - Bin Wu
- The Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Taekjip Ha
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Baltimore, MD 21205, USA
| | - Takanari Inoue
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA; The Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Erik M Jorgensen
- HHMI, Department of Biology, University of Utah, Salt Lake City, UT 84112-0840, USA
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK; The Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK; Simons Initiatives for the Developing Brain, University of Edinburgh, Edinburgh, Scotland EH8 9XD, UK
| | - Christian Rosenmund
- Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Berlin, Germany.
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University, Baltimore, MD 21205, USA; The Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA.
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45
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Rizo J, David G, Fealey ME, Jaczynska K. On the difficulties of characterizing weak protein interactions that are critical for neurotransmitter release. FEBS Open Bio 2022; 12:1912-1938. [PMID: 35986639 PMCID: PMC9623538 DOI: 10.1002/2211-5463.13473] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/09/2022] [Accepted: 08/18/2022] [Indexed: 01/25/2023] Open
Abstract
The mechanism of neurotransmitter release has been extensively characterized, showing that vesicle fusion is mediated by the SNARE complex formed by syntaxin-1, SNAP-25 and synaptobrevin. This complex is disassembled by N-ethylmaleimide sensitive factor (NSF) and SNAPs to recycle the SNAREs, whereas Munc18-1 and Munc13s organize SNARE complex assembly in an NSF-SNAP-resistant manner. Synaptotagmin-1 acts as the Ca2+ sensor that triggers exocytosis in a tight interplay with the SNAREs and complexins. Here, we review technical aspects associated with investigation of protein interactions underlying these steps, which is hindered because the release machinery is assembled between two membranes and is highly dynamic. Moreover, weak interactions, which are difficult to characterize, play key roles in neurotransmitter release, for instance by lowering energy barriers that need to be overcome in this highly regulated process. We illustrate the crucial role that structural biology has played in uncovering mechanisms underlying neurotransmitter release, but also discuss the importance of considering the limitations of the techniques used, including lessons learned from research in our lab and others. In particular, we emphasize: (a) the promiscuity of some protein sequences, including membrane-binding regions that can mediate irrelevant interactions with proteins in the absence of their native targets; (b) the need to ensure that weak interactions observed in crystal structures are biologically relevant; and (c) the limitations of isothermal titration calorimetry to analyze weak interactions. Finally, we stress that even studies that required re-interpretation often helped to move the field forward by improving our understanding of the system and providing testable hypotheses.
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Affiliation(s)
- Josep Rizo
- Department of BiophysicsUniversity of Texas Southwestern Medical CenterDallasTXUSA,Department of BiochemistryUniversity of Texas Southwestern Medical CenterDallasTXUSA,Department of PharmacologyUniversity of Texas Southwestern Medical CenterDallasTXUSA
| | - Guillaume David
- Department of BiophysicsUniversity of Texas Southwestern Medical CenterDallasTXUSA,Department of BiochemistryUniversity of Texas Southwestern Medical CenterDallasTXUSA,Department of PharmacologyUniversity of Texas Southwestern Medical CenterDallasTXUSA
| | - Michael E. Fealey
- Department of BiophysicsUniversity of Texas Southwestern Medical CenterDallasTXUSA,Department of BiochemistryUniversity of Texas Southwestern Medical CenterDallasTXUSA,Department of PharmacologyUniversity of Texas Southwestern Medical CenterDallasTXUSA
| | - Klaudia Jaczynska
- Department of BiophysicsUniversity of Texas Southwestern Medical CenterDallasTXUSA,Department of BiochemistryUniversity of Texas Southwestern Medical CenterDallasTXUSA,Department of PharmacologyUniversity of Texas Southwestern Medical CenterDallasTXUSA
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A sequential two-step priming scheme reproduces diversity in synaptic strength and short-term plasticity. Proc Natl Acad Sci U S A 2022; 119:e2207987119. [PMID: 35969787 PMCID: PMC9407230 DOI: 10.1073/pnas.2207987119] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Central nervous system synapses are diverse in strength and plasticity. Short-term plasticity has traditionally been evaluated with models postulating a single pool of functionally homogeneous fusion-competent synaptic vesicles. Many observations are not easily explainable by such simple models. We established and experimentally validated a scheme of synaptic vesicle priming consisting of two sequential and reversible steps of release–machinery assembly. This sequential two-step priming scheme faithfully reproduced plasticity at a glutamatergic model synapse. The proposed priming and fusion scheme was consistent with the measured mean responses and with the experimentally observed heterogeneity between synapses. Vesicle fusion probability was found to be relatively uniform among synapses, while the priming equilibrium at rest of mature versus immature vesicle priming states differed greatly. Glutamatergic synapses display variable strength and diverse short-term plasticity (STP), even for a given type of connection. Using nonnegative tensor factorization and conventional state modeling, we demonstrate that a kinetic scheme consisting of two sequential and reversible steps of release–machinery assembly and a final step of synaptic vesicle (SV) fusion reproduces STP and its diversity among synapses. Analyzing transmission at the calyx of Held synapses reveals that differences in synaptic strength and STP are not primarily caused by variable fusion probability (pfusion) but are determined by the fraction of docked synaptic vesicles equipped with a mature release machinery. Our simulations show that traditional quantal analysis methods do not necessarily report pfusion of SVs with a mature release machinery but reflect both pfusion and the distribution between mature and immature priming states at rest. Thus, the approach holds promise for a better mechanistic dissection of the roles of presynaptic proteins in the sequence of SV docking, two-step priming, and fusion. It suggests a mechanism for activity-induced redistribution of synaptic efficacy.
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47
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Kobbersmed JRL, Berns MMM, Ditlevsen S, Sørensen JB, Walter AM. Allosteric stabilization of calcium and phosphoinositide dual binding engages several synaptotagmins in fast exocytosis. eLife 2022; 11:74810. [PMID: 35929728 PMCID: PMC9489213 DOI: 10.7554/elife.74810] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 08/04/2022] [Indexed: 12/04/2022] Open
Abstract
Synaptic communication relies on the fusion of synaptic vesicles with the plasma membrane, which leads to neurotransmitter release. This exocytosis is triggered by brief and local elevations of intracellular Ca2+ with remarkably high sensitivity. How this is molecularly achieved is unknown. While synaptotagmins confer the Ca2+ sensitivity of neurotransmitter exocytosis, biochemical measurements reported Ca2+ affinities too low to account for synaptic function. However, synaptotagmin’s Ca2+ affinity increases upon binding the plasma membrane phospholipid PI(4,5)P2 and, vice versa, Ca2+ binding increases synaptotagmin’s PI(4,5)P2 affinity, indicating a stabilization of the Ca2+/PI(4,5)P2 dual-bound state. Here, we devise a molecular exocytosis model based on this positive allosteric stabilization and the assumptions that (1.) synaptotagmin Ca2+/PI(4,5)P2 dual binding lowers the energy barrier for vesicle fusion and that (2.) the effect of multiple synaptotagmins on the energy barrier is additive. The model, which relies on biochemically measured Ca2+/PI(4,5)P2 affinities and protein copy numbers, reproduced the steep Ca2+ dependency of neurotransmitter release. Our results indicate that each synaptotagmin engaging in Ca2+/PI(4,5)P2 dual-binding lowers the energy barrier for vesicle fusion by ~5 kBT and that allosteric stabilization of this state enables the synchronized engagement of several (typically three) synaptotagmins for fast exocytosis. Furthermore, we show that mutations altering synaptotagmin’s allosteric properties may show dominant-negative effects, even though synaptotagmins act independently on the energy barrier, and that dynamic changes of local PI(4,5)P2 (e.g. upon vesicle movement) dramatically impact synaptic responses. We conclude that allosterically stabilized Ca2+/PI(4,5)P2 dual binding enables synaptotagmins to exert their coordinated function in neurotransmission. For our brains and nervous systems to work properly, the nerve cells within them must be able to ‘talk’ to each other. They do this by releasing chemical signals called neurotransmitters which other cells can detect and respond to. Neurotransmitters are packaged in tiny membrane-bound spheres called vesicles. When a cell of the nervous system needs to send a signal to its neighbours, the vesicles fuse with the outer membrane of the cell, discharging their chemical contents for other cells to detect. The initial trigger for neurotransmitter release is a short, fast increase in the amount of calcium ions inside the signalling cell. One of the main proteins that helps regulate this process is synaptotagmin which binds to calcium and gives vesicles the signal to start unloading their chemicals. Despite acting as a calcium sensor, synaptotagmin actually has a very low affinity for calcium ions by itself, meaning that it would not be efficient for the protein to respond alone. Synpatotagmin is more likely to bind to calcium if it is attached to a molecule called PIP2, which is found in the membranes of cells The effect also occurs in reverse, as the binding of calcium to synaptotagmin increases the protein’s affinity for PIP2. However, how these three molecules – synaptotagmin, PIP2, and calcium – work together to achieve the physiological release of neurotransmitters is poorly understood. To help answer this question, Kobbersmed, Berns et al. set up a computer simulation of ‘virtual vesicles’ using available experimental data on synaptotagmin’s affinity with calcium and PIP2. In this simulation, synaptotagmin could only trigger the release of neurotransmitters when bound to both calcium and PIP2. The model also showed that each ‘complex’ of synaptotagmin/calcium/PIP2 made the vesicles more likely to fuse with the outer membrane of the cell – to the extent that only a handful of synaptotagmin molecules were needed to start neurotransmitter release from a single vesicle. These results shed new light on a biological process central to the way nerve cells communicate with each other. In the future, Kobbersmed, Berns et al. hope that this insight will help us to understand the cause of diseases where communication in the nervous system is impaired.
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Affiliation(s)
- Janus R L Kobbersmed
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Manon M M Berns
- Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | - Susanne Ditlevsen
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Alexander M Walter
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
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48
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Quintanilla J, Jia Y, Lauterborn JC, Pruess BS, Le AA, Cox CD, Gall CM, Lynch G, Gunn BG. Novel types of frequency filtering in the lateral perforant path projections to dentate gyrus. J Physiol 2022; 600:3865-3896. [PMID: 35852108 PMCID: PMC9513824 DOI: 10.1113/jp283012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 06/26/2022] [Indexed: 11/08/2022] Open
Abstract
Despite its evident importance to learning theory and models, the manner in which the lateral perforant path (LPP) transforms signals from entorhinal cortex to hippocampus is not well understood. The present studies measured synaptic responses in the dentate gyrus (DG) of adult mouse hippocampal slices during different patterns of LPP stimulation. Theta (5 Hz) stimulation produced a modest within-train facilitation that was markedly enhanced at the level of DG output. Gamma (50 Hz) activation resulted in a singular pattern with initial synaptic facilitation being followed by a progressively greater depression. DG output was absent after only two pulses. Reducing release probability with low extracellular calcium instated frequency facilitation to gamma stimulation while long-term potentiation, which increases release by LPP terminals, enhanced within-train depression. Relatedly, per terminal concentrations of VGLUT2, a vesicular glutamate transporter associated with high release probability, were much greater in the LPP than in CA3-CA1 connections. Attempts to circumvent the potent gamma filter using a series of short (three-pulse) 50 Hz trains spaced by 200 ms were only partially successful: composite responses were substantially reduced after the first burst, an effect opposite to that recorded in field CA1. The interaction between bursts was surprisingly persistent (>1.0 s). Low calcium improved throughput during theta/gamma activation but buffering of postsynaptic calcium did not. In all, presynaptic specializations relating to release probability produce an unusual but potent type of frequency filtering in the LPP. Patterned burst input engages a different type of filter with substrates that are also likely to be located presynaptically. KEY POINTS: The lateral perforant path (LPP)-dentate gyrus (DG) synapse operates as a low-pass filter, where responses to a train of 50 Hz, γ frequency activation are greatly suppressed. Activation with brief bursts of γ frequency information engages a secondary filter that persists for prolonged periods (lasting seconds). Both forms of LPP frequency filtering are influenced by presynaptic, as opposed to postsynaptic, processes; this contrasts with other hippocampal synapses. LPP frequency filtering is modified by the unique presynaptic long-term potentiation at this synapse. Computational simulations indicate that presynaptic factors associated with release probability and vesicle recycling may underlie the potent LPP-DG frequency filtering.
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Affiliation(s)
- Julian Quintanilla
- Departments of Anatomy & Neurobiology, University of California, Irvine, CA, USA
| | - Yousheng Jia
- Departments of Anatomy & Neurobiology, University of California, Irvine, CA, USA
| | - Julie C Lauterborn
- Departments of Anatomy & Neurobiology, University of California, Irvine, CA, USA
| | - Benedict S Pruess
- Departments of Anatomy & Neurobiology, University of California, Irvine, CA, USA
| | - Aliza A Le
- Departments of Anatomy & Neurobiology, University of California, Irvine, CA, USA
| | - Conor D Cox
- Departments of Anatomy & Neurobiology, University of California, Irvine, CA, USA
| | - Christine M Gall
- Departments of Anatomy & Neurobiology, University of California, Irvine, CA, USA.,Departments of Neurobiology & Behavior, University of California, Irvine, CA, USA
| | - Gary Lynch
- Departments of Anatomy & Neurobiology, University of California, Irvine, CA, USA.,Departments of Psychiatry & Human Behavior, University of California, Irvine, CA, USA
| | - Benjamin G Gunn
- Departments of Anatomy & Neurobiology, University of California, Irvine, CA, USA
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49
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Mendonça PRF, Tagliatti E, Langley H, Kotzadimitriou D, Zamora-Chimal CG, Timofeeva Y, Volynski KE. Asynchronous glutamate release is enhanced in low release efficacy synapses and dispersed across the active zone. Nat Commun 2022; 13:3497. [PMID: 35715404 PMCID: PMC9206079 DOI: 10.1038/s41467-022-31070-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 05/31/2022] [Indexed: 11/09/2022] Open
Abstract
The balance between fast synchronous and delayed asynchronous release of neurotransmitters has a major role in defining computational properties of neuronal synapses and regulation of neuronal network activity. However, how it is tuned at the single synapse level remains poorly understood. Here, using the fluorescent glutamate sensor SF-iGluSnFR, we image quantal vesicular release in tens to hundreds of individual synaptic outputs from single pyramidal cells with 4 millisecond temporal and 75 nm spatial resolution. We find that the ratio between synchronous and asynchronous synaptic vesicle exocytosis varies extensively among synapses supplied by the same axon, and that the synchronicity of release is reduced at low release probability synapses. We further demonstrate that asynchronous exocytosis sites are more widely distributed within the release area than synchronous sites. Together, our results reveal a universal relationship between the two major functional properties of synapses - the timing and the overall efficacy of neurotransmitter release.
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Affiliation(s)
- Philipe R F Mendonça
- University College London Institute of Neurology, London, UK. .,Department of Physiology and Biophysics, Federal University of Minas Gerais, Gerais, Brazil.
| | - Erica Tagliatti
- University College London Institute of Neurology, London, UK
| | - Helen Langley
- University College London Institute of Neurology, London, UK
| | | | | | - Yulia Timofeeva
- University College London Institute of Neurology, London, UK. .,Department of Computer Science, University of Warwick, Coventry, UK.
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50
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Rizo J, Sari L, Qi Y, Im W, Lin MM. All-atom molecular dynamics simulations of Synaptotagmin-SNARE-complexin complexes bridging a vesicle and a flat lipid bilayer. eLife 2022; 11:76356. [PMID: 35708237 PMCID: PMC9239685 DOI: 10.7554/elife.76356] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 06/15/2022] [Indexed: 12/14/2022] Open
Abstract
Synaptic vesicles are primed into a state that is ready for fast neurotransmitter release upon Ca2+-binding to Synaptotagmin-1. This state likely includes trans-SNARE complexes between the vesicle and plasma membranes that are bound to Synaptotagmin-1 and complexins. However, the nature of this state and the steps leading to membrane fusion are unclear, in part because of the difficulty of studying this dynamic process experimentally. To shed light into these questions, we performed all-atom molecular dynamics simulations of systems containing trans-SNARE complexes between two flat bilayers or a vesicle and a flat bilayer with or without fragments of Synaptotagmin-1 and/or complexin-1. Our results need to be interpreted with caution because of the limited simulation times and the absence of key components, but suggest mechanistic features that may control release and help visualize potential states of the primed Synaptotagmin-1-SNARE-complexin-1 complex. The simulations suggest that SNAREs alone induce formation of extended membrane-membrane contact interfaces that may fuse slowly, and that the primed state contains macromolecular assemblies of trans-SNARE complexes bound to the Synaptotagmin-1 C2B domain and complexin-1 in a spring-loaded configuration that prevents premature membrane merger and formation of extended interfaces, but keeps the system ready for fast fusion upon Ca2+ influx.
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Affiliation(s)
- Josep Rizo
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Levent Sari
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, United States.,Green Center for Systems Biology, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Yife Qi
- Department of Medicinal Chemistry, School of Pharmacy, Fudan University, Shanghai, China
| | - Wonpil Im
- Department of Biological Sciences, Lehigh University, Bethlehem, United States.,Department of Chemistry, Lehigh University, Bethlehem, United States.,Department of Bioengineering, Lehigh University, Bethlehem, United States.,Department of Computer Science and Engineering, Lehigh University, Bethlehem, United States
| | - Milo M Lin
- Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, United States.,Green Center for Systems Biology, The University of Texas Southwestern Medical Center, Dallas, United States
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