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Klose MK, Kim J, Schmidt BF, Levitan E. Circadian Vesicle Capture Prepares Clock Neuron Synapses for Daily Phase-Delayed Neuropeptide Release. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.01.569590. [PMID: 38106047 PMCID: PMC10723267 DOI: 10.1101/2023.12.01.569590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Drosophila sLNv clock neurons release the neuropeptide PDF to control circadian rhythms. Strikingly, PDF content in sLNv terminals is rhythmic with a peak in the morning hours prior to the onset of activity-dependent release. Because synaptic PDF accumulation, rather than synaptic release, aligns with the late-night elevations in both sLNv neuron excitability and Ca2+, we explored the dependence of presynaptic neuropeptide accumulation on neuropeptide vesicle transport, electrical activity and the circadian clock. Live imaging reveals that anterograde axonal transport is constant throughout the day and capture of circulating neuropeptide vesicles rhythmically boosts presynaptic neuropeptide content hours prior to release. The late-night surge in vesicle capture, like release, requires electrical activity and results in a large releasable pool of presynaptic vesicles to support the later burst of neuropeptide release. The circadian clock is also required suggesting that it controls the switch from vesicle capture to exocytosis, which are normally coupled activity-dependent processes. This toggling of activity transduction maximizes rhythmic synaptic neuropeptide release needed for robust circadian behavior and resolves the previously puzzling delay in timing of synaptic neuropeptide release relative to changes in sLNv clock neuron physiology.
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2
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Xiong GJ, Sheng ZH. Presynaptic perspective: Axonal transport defects in neurodevelopmental disorders. J Cell Biol 2024; 223:e202401145. [PMID: 38568173 PMCID: PMC10988239 DOI: 10.1083/jcb.202401145] [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: 01/27/2024] [Revised: 03/20/2024] [Accepted: 03/21/2024] [Indexed: 04/05/2024] Open
Abstract
Disruption of synapse assembly and maturation leads to a broad spectrum of neurodevelopmental disorders. Presynaptic proteins are largely synthesized in the soma, where they are packaged into precursor vesicles and transported into distal axons to ensure precise assembly and maintenance of presynapses. Due to their morphological features, neurons face challenges in the delivery of presynaptic cargos to nascent boutons. Thus, targeted axonal transport is vital to build functional synapses. A growing number of mutations in genes encoding the transport machinery have been linked to neurodevelopmental disorders. Emerging lines of evidence have started to uncover presynaptic mechanisms underlying axonal transport defects, thus broadening the view of neurodevelopmental disorders beyond postsynaptic mechanisms. In this review, we discuss presynaptic perspectives of neurodevelopmental disorders by focusing on impaired axonal transport and disturbed assembly and maintenance of presynapses. We also discuss potential strategies for restoring axonal transport as an early therapeutic intervention.
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Affiliation(s)
- Gui-Jing Xiong
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Zu-Hang Sheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
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3
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Kirchner MK, Althammer F, Donaldson KJ, Cox DN, Stern JE. Changes in neuropeptide large dense core vesicle trafficking dynamics contribute to adaptive responses to a systemic homeostatic challenge. iScience 2023; 26:108243. [PMID: 38026155 PMCID: PMC10654599 DOI: 10.1016/j.isci.2023.108243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/28/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Neuropeptides are packed into large dense core vesicles (LDCVs) that are transported from the soma out into their processes. Limited information exists regarding mechanisms regulating LDCV trafficking, particularly during challenges to bodily homeostasis. Addressing this gap, we used 2-photon imaging in an ex vivo preparation to study LDCVs trafficking dynamics in vasopressin (VP) neurons, which traffic and release neuropeptide from their dendrites and axons. We report a dynamic bidirectional trafficking of VP-LDCVs with important differences in speed and directionality between axons and dendrites. Acute, short-lasting stimuli known to alter VP firing activity and axonal/dendritic release caused modest changes in VP-LDCVs trafficking dynamics. Conversely, chronic/sustained systemic osmotic challenges upregulated VP-LDCVs trafficking dynamic, with a larger effect in dendrites. These results support differential regulation of dendritic and axonal LDCV trafficking, and that changes in trafficking dynamics constitute a novel mechanism by which peptidergic neurons can efficiently adapt to conditions of increased hormonal demand.
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Affiliation(s)
- Matthew K. Kirchner
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA 30303, USA
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
| | - Ferdinand Althammer
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA 30303, USA
- Institute of Human Genetics, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Kevin J. Donaldson
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
- Center for Neuromics, Georgia State University, Atlanta, GA 30303, USA
| | - Daniel N. Cox
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
- Center for Neuromics, Georgia State University, Atlanta, GA 30303, USA
| | - Javier E. Stern
- Center for Neuroinflammation and Cardiometabolic Diseases, Georgia State University, Atlanta, GA 30303, USA
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303, USA
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4
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Georgiev SV, Rizzoli SO. The long-loop recycling (LLR) of synaptic components as a question of economics. Mol Cell Neurosci 2023; 126:103862. [PMID: 37236414 DOI: 10.1016/j.mcn.2023.103862] [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: 02/28/2023] [Revised: 05/15/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023] Open
Abstract
The pre- and post-synaptic compartments contain a variety of molecules that are known to recycle between the plasma membrane and intracellular organelles. The recycling steps have been amply described in functional terms, with, for example, synaptic vesicle recycling being essential for neurotransmitter release, and postsynaptic receptor recycling being a fundamental feature of synaptic plasticity. However, synaptic protein recycling may also serve a more prosaic role, simply ensuring the repeated use of specific components, thereby minimizing the energy expenditure on the synthesis of synaptic proteins. This type of process has been recently described for components of the extracellular matrix, which undergo long-loop recycling (LLR), to and from the cell body. Here we suggest that the energy-saving recycling of synaptic components may be more widespread than is generally acknowledged, potentially playing a role in both synaptic vesicle protein usage and postsynaptic receptor metabolism.
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Affiliation(s)
- Svilen Veselinov Georgiev
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Germany; International Max Planck Research School for Neuroscience, Göttingen, Germany.
| | - Silvio O Rizzoli
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Germany; Biostructural Imaging of Neurodegeneration (BIN) Center, Göttingen, Germany; Excellence Cluster Multiscale Bioimaging, Göttingen, Germany.
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5
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Vitet H, Bruyère J, Xu H, Séris C, Brocard J, Abada YS, Delatour B, Scaramuzzino C, Venance L, Saudou F. Huntingtin recruits KIF1A to transport synaptic vesicle precursors along the mouse axon to support synaptic transmission and motor skill learning. eLife 2023; 12:e81011. [PMID: 37431882 PMCID: PMC10365837 DOI: 10.7554/elife.81011] [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: 06/13/2022] [Accepted: 07/06/2023] [Indexed: 07/12/2023] Open
Abstract
Neurotransmitters are released at synapses by synaptic vesicles (SVs), which originate from SV precursors (SVPs) that have traveled along the axon. Because each synapse maintains a pool of SVs, only a small fraction of which are released, it has been thought that axonal transport of SVPs does not affect synaptic function. Here, studying the corticostriatal network both in microfluidic devices and in mice, we find that phosphorylation of the Huntingtin protein (HTT) increases axonal transport of SVPs and synaptic glutamate release by recruiting the kinesin motor KIF1A. In mice, constitutive HTT phosphorylation causes SV over-accumulation at synapses, increases the probability of SV release, and impairs motor skill learning on the rotating rod. Silencing KIF1A in these mice restored SV transport and motor skill learning to wild-type levels. Axonal SVP transport within the corticostriatal network thus influences synaptic plasticity and motor skill learning.
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Affiliation(s)
- Hélène Vitet
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Julie Bruyère
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Hao Xu
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSLParisFrance
| | - Claire Séris
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Jacques Brocard
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Yah-Sé Abada
- Sorbonne Université, Institut du Cerveau, Paris Brain Institute, ICM, Inserm U1127, CNRS UMR7225ParisFrance
| | - Benoît Delatour
- Sorbonne Université, Institut du Cerveau, Paris Brain Institute, ICM, Inserm U1127, CNRS UMR7225ParisFrance
| | - Chiara Scaramuzzino
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
| | - Laurent Venance
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSLParisFrance
| | - Frédéric Saudou
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut NeuroscienceGrenobleFrance
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6
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Feresten AH, Bhat JM, Yu AJ, Zapf R, Rankin CH, Hutter H. wrk-1 and rig-5 control pioneer and follower axon navigation in the ventral nerve cord of Caenorhabditis elegans in a nid-1 mutant background. Genetics 2023; 223:iyac187. [PMID: 36573271 PMCID: PMC9991498 DOI: 10.1093/genetics/iyac187] [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: 08/17/2022] [Accepted: 12/10/2022] [Indexed: 12/28/2022] Open
Abstract
During nervous system development, neurons send out axons, which must navigate large distances to reach synaptic targets. Axons grow out sequentially. The early outgrowing axons, pioneers, must integrate information from various guidance cues in their environment to determine the correct direction of outgrowth. Later outgrowing follower axons can at least in part navigate by adhering to pioneer axons. In Caenorhabditis elegans, the right side of the largest longitudinal axon tract, the ventral nerve cord, is pioneered by the AVG axon. How the AVG axon navigates is only partially understood. In this study, we describe the role of two members of the IgCAM family, wrk-1 and rig-5, in AVG axon navigation. While wrk-1 and rig-5 single mutants do not show AVG navigation defects, both mutants have highly penetrant pioneer and follower navigation defects in a nid-1 mutant background. Both mutations increase the fraction of follower axons following the misguided pioneer axon. We found that wrk-1 and rig-5 act in different genetic pathways, suggesting that we identified two pioneer-independent guidance pathways used by follower axons. We assessed general locomotion, mechanosensory responsiveness, and habituation to determine whether axonal navigation defects impact nervous system function. In rig-5 nid-1 double mutants, we found no significant defects in free movement behavior; however, a subpopulation of animals shows minor changes in response duration habituation after mechanosensory stimulation. These results suggest that guidance defects of axons in the motor circuit do not necessarily lead to major movement or behavioral defects but impact more complex behavioral modulation.
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Affiliation(s)
- Abigail H Feresten
- Department of Biological Sciences, and Center for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC V5A1S6, Canada
| | - Jaffar M Bhat
- Department of Biological Sciences, and Center for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC V5A1S6, Canada
| | - Alex J Yu
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T2B5, Canada
| | - Richard Zapf
- Department of Biological Sciences, and Center for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC V5A1S6, Canada
| | - Catharine H Rankin
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T2B5, Canada
- Department of Psychology, University of British Columbia, Vancouver, BC V6T1Z4, Canada
| | - Harald Hutter
- Department of Biological Sciences, and Center for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, BC V5A1S6, Canada
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7
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Liessem S, Held M, Bisen RS, Haberkern H, Lacin H, Bockemühl T, Ache JM. Behavioral state-dependent modulation of insulin-producing cells in Drosophila. Curr Biol 2023; 33:449-463.e5. [PMID: 36580915 DOI: 10.1016/j.cub.2022.12.005] [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: 06/23/2022] [Revised: 11/01/2022] [Accepted: 12/02/2022] [Indexed: 12/29/2022]
Abstract
Insulin signaling plays a pivotal role in metabolic control and aging, and insulin accordingly is a key factor in several human diseases. Despite this importance, the in vivo activity dynamics of insulin-producing cells (IPCs) are poorly understood. Here, we characterized the effects of locomotion on the activity of IPCs in Drosophila. Using in vivo electrophysiology and calcium imaging, we found that IPCs were strongly inhibited during walking and flight and that their activity rebounded and overshot after cessation of locomotion. Moreover, IPC activity changed rapidly during behavioral transitions, revealing that IPCs are modulated on fast timescales in behaving animals. Optogenetic activation of locomotor networks ex vivo, in the absence of actual locomotion or changes in hemolymph sugar levels, was sufficient to inhibit IPCs. This demonstrates that the behavioral state-dependent inhibition of IPCs is actively controlled by neuronal pathways and is independent of changes in glucose concentration. By contrast, the overshoot in IPC activity after locomotion was absent ex vivo and after starvation, indicating that it was not purely driven by feedforward signals but additionally required feedback derived from changes in hemolymph sugar concentration. We hypothesize that IPC inhibition during locomotion supports mobilization of fuel stores during metabolically demanding behaviors, while the rebound in IPC activity after locomotion contributes to replenishing muscle glycogen stores. In addition, the rapid dynamics of IPC modulation support a potential role of insulin in the state-dependent modulation of sensorimotor processing.
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Affiliation(s)
- Sander Liessem
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, Julius-Maximilians-University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Martina Held
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, Julius-Maximilians-University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Rituja S Bisen
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, Julius-Maximilians-University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Hannah Haberkern
- HHMI Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Haluk Lacin
- Department of Genetics, Washington University School of Medicine, 4523 Clayton Avenue, St Louis, MO 63110, USA
| | - Till Bockemühl
- Department of Biology, Institute of Zoology, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
| | - Jan M Ache
- Neurobiology and Genetics, Theodor-Boveri-Institute, Biocenter, Julius-Maximilians-University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
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8
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Palumbos SD, Holzbaur ELF. VAB-8 stops dynein in its tracks to regulate synaptic delivery. Dev Cell 2022; 57:1789-1791. [PMID: 35944475 DOI: 10.1016/j.devcel.2022.07.009] [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: 11/17/2022]
Abstract
How synaptogenic signals trigger the targeted delivery of synaptic material is a fundamental question in neuroscience. In this issue of Developmental Cell, Balseiro-Gomez et al. identify a mechanism through which local synatogenic pathways control synaptic cargo delivery.
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Affiliation(s)
- Sierra D Palumbos
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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9
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Balseiro-Gómez S, Park J, Yue Y, Ding C, Shao L, Ҫetinkaya S, Kuzoian C, Hammarlund M, Verhey KJ, Yogev S. Neurexin and frizzled intercept axonal transport at microtubule minus ends to control synapse formation. Dev Cell 2022; 57:1802-1816.e4. [PMID: 35809561 PMCID: PMC9378695 DOI: 10.1016/j.devcel.2022.06.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 02/01/2022] [Accepted: 06/13/2022] [Indexed: 01/29/2023]
Abstract
Synapse formation is locally determined by transmembrane proteins, yet synaptic material is synthesized remotely and undergoes processive transport in axons. How local synaptogenic signals intercept synaptic cargo in transport to promote its delivery and synapse formation is unknown. We found that the control of synaptic cargo delivery at microtubule (MT) minus ends mediates pro- and anti-synaptogenic activities of presynaptic neurexin and frizzled in C. elegans and identified the atypical kinesin VAB-8/KIF26 as a key molecule in this process. VAB-8/KIF26 levels at synaptic MT minus ends are controlled by frizzled and neurexin; loss of VAB-8 mimics neurexin mutants or frizzled hyperactivation, and its overexpression can rescue synapse loss in these backgrounds. VAB-8/KIF26 is required for the synaptic localization of other minus-end proteins and promotes the pausing of retrograde transport to allow delivery to synapses. Consistently, reducing retrograde transport rescues synapse loss in vab-8 and neurexin mutants. These results uncover a mechanistic link between synaptogenic signaling and axonal transport.
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Affiliation(s)
- Santiago Balseiro-Gómez
- Department of Neuroscience, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA
| | - Junhyun Park
- Department of Neuroscience, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA
| | - Yang Yue
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Chen Ding
- Department of Neuroscience, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA; Department of Genetics, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA
| | - Lin Shao
- Department of Neuroscience, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA
| | - Selim Ҫetinkaya
- Department of Neuroscience, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA
| | - Caroline Kuzoian
- Department of Neuroscience, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA
| | - Marc Hammarlund
- Department of Neuroscience, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA; Department of Genetics, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA
| | - Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Shaul Yogev
- Department of Neuroscience, Yale School of Medicine, 295 Congress Avenue, New Haven, CT 06510, USA.
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10
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Thyagarajan P, Feng C, Lee D, Shorey M, Rolls MM. Microtubule polarity is instructive for many aspects of neuronal polarity. Dev Biol 2022; 486:56-70. [PMID: 35341730 PMCID: PMC9058238 DOI: 10.1016/j.ydbio.2022.03.009] [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: 11/29/2021] [Revised: 03/04/2022] [Accepted: 03/22/2022] [Indexed: 11/25/2022]
Abstract
Many neurons in bilaterian animals are polarized with functionally distinct axons and dendrites. Microtubule polarity, microtubule stability, and the axon initial segment (AIS) have all been shown to influence polarized transport in neurons. Each of these cytoskeletal cues could act independently to control axon and dendrite identity, or there could be a hierarchy in which one acts upstream of the others. Here we test the hypothesis that microtubule polarity acts as a master regulator of neuronal polarity by using a Drosophila genetic background in which some dendrites have normal minus-end-out microtubule polarity and others have the axonal plus-end-out polarity. In these mosaic dendrite arbors, we found that ribosomes, which are more abundant in dendrites than axons, were reduced in plus-end-out dendrites, while an axonal cargo was increased. In addition, we determined that microtubule stability was different in plus-end-out and minus-end-out dendrites, with plus-end-out ones having more stable microtubules like axons. Similarly, we found that ectopic diffusion barriers, like those at the AIS, formed at the base of dendrites with plus-end-out regions. Thus, changes in microtubule polarity were sufficient to rearrange other cytoskeletal features associated with neuronal polarization. However, overall neuron shape was maintained with only subtle changes in branching in mosaic arbors. We conclude that microtubule polarity can act upstream of many aspects of intracellular neuronal polarization, but shape is relatively resilient to changes in microtubule polarity in vivo.
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Affiliation(s)
- Pankajam Thyagarajan
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Chengye Feng
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - David Lee
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Matthew Shorey
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Melissa M Rolls
- Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
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11
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Selective motor activation in organelle transport along axons. Nat Rev Mol Cell Biol 2022; 23:699-714. [DOI: 10.1038/s41580-022-00491-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2022] [Indexed: 12/17/2022]
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12
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Tang F, Fan J, Zhang X, Zou Z, Xiao D, Li X. The Role of Vti1a in Biological Functions and Its Possible Role in Nervous System Disorders. Front Mol Neurosci 2022; 15:918664. [PMID: 35711736 PMCID: PMC9197314 DOI: 10.3389/fnmol.2022.918664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 05/09/2022] [Indexed: 11/24/2022] Open
Abstract
Vesicle transport through interaction with t-SNAREs 1A (Vti1a), a member of the N-ethylmaleimide-sensitive factor attachment protein receptor protein family, is involved in cell signaling as a vesicular protein and mediates vesicle trafficking. Vti1a appears to have specific roles in neurons, primarily by regulating upstream neurosecretory events that mediate exocytotic proteins and the availability of secretory organelles, as well as regulating spontaneous synaptic transmission and postsynaptic efficacy to control neurosecretion. Vti1a also has essential roles in neural development, autophagy, and unconventional extracellular transport of neurons. Studies have shown that Vti1a dysfunction plays critical roles in pathological mechanisms of Hepatic encephalopathy by influencing spontaneous neurotransmission. It also may have an unknown role in amyotrophic lateral sclerosis. A VTI1A variant is associated with the risk of glioma, and the fusion product of the VTI1A gene and the adjacent TCF7L2 gene is involved in glioma development. This review summarizes Vti1a functions in neurons and highlights the role of Vti1a in the several nervous system disorders.
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Affiliation(s)
- Fajuan Tang
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
| | - Jiali Fan
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
| | - Xiaoyan Zhang
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
| | - Zhuan Zou
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
| | - Dongqiong Xiao
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
- Dongqiong Xiao,
| | - Xihong Li
- Department of Emergency, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, China
- *Correspondence: Xihong Li,
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13
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Kuznetsov IA, Kuznetsov AV. Bidirectional, unlike unidirectional transport, allows transporting axonal cargos against their concentration gradient. J Theor Biol 2022; 546:111161. [DOI: 10.1016/j.jtbi.2022.111161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 05/04/2022] [Accepted: 05/06/2022] [Indexed: 11/25/2022]
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14
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Ferdos S, Brockhaus J, Missler M, Rohlmann A. Deletion of β-Neurexins in Mice Alters the Distribution of Dense-Core Vesicles in Presynapses of Hippocampal and Cerebellar Neurons. Front Neuroanat 2022; 15:757017. [PMID: 35173587 PMCID: PMC8841415 DOI: 10.3389/fnana.2021.757017] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 12/16/2021] [Indexed: 11/17/2022] Open
Abstract
Communication between neurons through synapses includes the release of neurotransmitter-containing synaptic vesicles (SVs) and of neuromodulator-containing dense-core vesicles (DCVs). Neurexins (Nrxns), a polymorphic family of cell surface molecules encoded by three genes in vertebrates (Nrxn1–3), have been proposed as essential presynaptic organizers and as candidates for cell type-specific or even synapse-specific regulation of synaptic vesicle exocytosis. However, it remains unknown whether Nrxns also regulate DCVs. Here, we report that at least β-neurexins (β-Nrxns), an extracellularly smaller Nrxn variant, are involved in the distribution of presynaptic DCVs. We found that conditional deletion of all three β-Nrxn isoforms in mice by lentivirus-mediated Cre recombinase expression in primary hippocampal neurons reduces the number of ultrastructurally identified DCVs in presynaptic boutons. Consistently, colabeling against marker proteins revealed a diminished population of chromogranin A- (ChrgA-) positive DCVs in synapses and axons of β-Nrxn-deficient neurons. Moreover, we validated the impaired DCV distribution in cerebellar brain tissue from constitutive β-Nrxn knockout (β-TKO) mice, where DCVs are normally abundant and β-Nrxn isoforms are prominently expressed. Finally, we observed that the ultrastructure and marker proteins of the Golgi apparatus, responsible for packaging neuropeptides into DCVs, seem unchanged. In conclusion, based on the validation from the two deletion strategies in conditional and constitutive KO mice, two neuronal populations from the hippocampus and cerebellum, and two experimental protocols in cultured neurons and in the brain tissue, this study presented morphological evidence that the number of DCVs at synapses is altered in the absence of β-Nrxns. Our results therefore point to an unexpected contribution of β-Nrxns to the organization of neuropeptide and neuromodulator function, in addition to their more established role in synaptic vesicle release.
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15
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Abstract
Transport of intracellular components relies on a variety of active and passive mechanisms, ranging from the diffusive spreading of small molecules over short distances to motor-driven motion across long distances. The cell-scale behavior of these mechanisms is fundamentally dependent on the morphology of the underlying cellular structures. Diffusion-limited reaction times can be qualitatively altered by the presence of occluding barriers or by confinement in complex architectures, such as those of reticulated organelles. Motor-driven transport is modulated by the architecture of cytoskeletal filaments that serve as transport highways. In this review, we discuss the impact of geometry on intracellular transport processes that fulfill a broad range of functional objectives, including delivery, distribution, and sorting of cellular components. By unraveling the interplay between morphology and transport efficiency, we aim to elucidate key structure-function relationships that govern the architecture of transport systems at the cellular scale. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Anamika Agrawal
- Department of Physics, University of California, San Diego, La Jolla, California, USA;
| | - Zubenelgenubi C Scott
- Department of Physics, University of California, San Diego, La Jolla, California, USA;
| | - Elena F Koslover
- Department of Physics, University of California, San Diego, La Jolla, California, USA;
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16
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Nassal JP, Murphy FH, Toonen RF, Verhage M. Differential axonal trafficking of Neuropeptide Y-, LAMP1-, and RAB7-tagged organelles in vivo. eLife 2022; 11:81721. [PMID: 36459486 PMCID: PMC9718525 DOI: 10.7554/elife.81721] [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: 07/08/2022] [Accepted: 11/22/2022] [Indexed: 12/04/2022] Open
Abstract
Different organelles traveling through neurons exhibit distinct properties in vitro, but this has not been investigated in the intact mammalian brain. We established simultaneous dual color two-photon microscopy to visualize the trafficking of Neuropeptide Y (NPY)-, LAMP1-, and RAB7-tagged organelles in thalamocortical axons imaged in mouse cortex in vivo. This revealed that LAMP1- and RAB7-tagged organelles move significantly faster than NPY-tagged organelles in both anterograde and retrograde direction. NPY traveled more selectively in anterograde direction than LAMP1 and RAB7. By using a synapse marker and a calcium sensor, we further investigated the transport dynamics of NPY-tagged organelles. We found that these organelles slow down and pause at synapses. In contrast to previous in vitro studies, a significant increase of transport speed was observed after spontaneous activity and elevated calcium levels in vivo as well as electrically stimulated activity in acute brain slices. Together, we show a remarkable diversity in speeds and properties of three axonal organelle marker in vivo that differ from properties previously observed in vitro.
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Affiliation(s)
- Joris P Nassal
- Departments of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU University Medical CenterAmsterdamNetherlands
| | - Fiona H Murphy
- Departments of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU University Medical CenterAmsterdamNetherlands
| | - Ruud F Toonen
- Departments of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU University Medical CenterAmsterdamNetherlands
| | - Matthijs Verhage
- Departments of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam and VU University Medical CenterAmsterdamNetherlands
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17
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Pagella S, Deussing JM, Kopp-Scheinpflug C. Expression Patterns of the Neuropeptide Urocortin 3 and Its Receptor CRFR2 in the Mouse Central Auditory System. Front Neural Circuits 2021; 15:747472. [PMID: 34867212 PMCID: PMC8633543 DOI: 10.3389/fncir.2021.747472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 10/18/2021] [Indexed: 11/16/2022] Open
Abstract
Sensory systems have to be malleable to context-dependent modulations occurring over different time scales, in order to serve their evolutionary function of informing about the external world while also eliciting survival-promoting behaviors. Stress is a major context-dependent signal that can have fast and delayed effects on sensory systems, especially on the auditory system. Urocortin 3 (UCN3) is a member of the corticotropin-releasing factor family. As a neuropeptide, UCN3 regulates synaptic activity much faster than the classic steroid hormones of the hypothalamic-pituitary-adrenal axis. Moreover, due to the lack of synaptic re-uptake mechanisms, UCN3 can have more long-lasting and far-reaching effects. To date, a modest number of studies have reported the presence of UCN3 or its receptor CRFR2 in the auditory system, particularly in the cochlea and the superior olivary complex, and have highlighted the importance of this stress neuropeptide for protecting auditory function. However, a comprehensive map of all neurons synthesizing UCN3 or CRFR2 within the auditory pathway is lacking. Here, we utilize two reporter mouse lines to elucidate the expression patterns of UCN3 and CRFR2 in the auditory system. Additional immunolabelling enables further characterization of the neurons that synthesize UCN3 or CRFR2. Surprisingly, our results indicate that within the auditory system, UCN3 is expressed predominantly in principal cells, whereas CRFR2 expression is strongest in non-principal, presumably multisensory, cell types. Based on the presence or absence of overlap between UCN3 and CRFR2 labeling, our data suggest unusual modes of neuromodulation by UCN3, involving volume transmission and autocrine signaling.
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Affiliation(s)
- Sara Pagella
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Jan M Deussing
- Research Group Molecular Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - Conny Kopp-Scheinpflug
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-University Munich, Munich, Germany
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18
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Kuznetsov IA, Kuznetsov AV. Simulation of a sudden drop-off in distal dense core vesicle concentration in Drosophila type II motoneuron terminals. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3523. [PMID: 34418891 DOI: 10.1002/cnm.3523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 08/14/2021] [Indexed: 06/13/2023]
Abstract
Recent experimental observations have shown evidence of an unexpected sudden drop-off in the dense core vesicles (DCVs) content at the ends of certain types of axon endings. This article seeks to determine whether these observations may be explained without modifying the parameters characterizing the ability of distal en passant boutons to capture and accumulate DCVs. We developed a mathematical model that is based on the conservation of captured and transiting DCVs in boutons. The model consists of 77 ordinary differential equations and is solved using a standard Matlab solver. We hypothesize that the drop in DCV content in distal boutons is due to an insufficient supply of anterogradely moving DCVs coming from the soma. As anterogradely moving DCVs are captured (and eventually destroyed) in more proximal boutons on their way to the end of the terminal, the fluxes of anterogradely moving DCVs between the boutons become increasingly smaller, and the most distal boutons are left without DCVs. We tested this hypothesis by modifying the flux of DCVs entering the terminal and found that the number of most distal boutons left unfilled increases if the DCV flux entering the terminal is decreased. The number of anterogradely moving DCVs in the axon can be increased either by the release of a portion of captured DCVs into the anterograde component or by an increase of the anterograde DCV flux into the terminal. This increase could lead to having enough anterogradely moving DCVs such that they could reach the most distal bouton and then turn around by changing molecular motors that propel them. The model suggests that this could result in an increased concentration of resident DCVs in distal boutons beginning with bouton 2 (the most distal is bouton 1). This is because in distal boutons, DCVs have a larger chance to be captured from the transiting state as they pass the boutons moving anterogradely and then again as they pass the same boutons moving retrogradely.
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Affiliation(s)
- Ivan A Kuznetsov
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Andrey V Kuznetsov
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina, USA
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19
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Agrawal A, Koslover EF. Optimizing mitochondrial maintenance in extended neuronal projections. PLoS Comput Biol 2021; 17:e1009073. [PMID: 34106921 PMCID: PMC8216566 DOI: 10.1371/journal.pcbi.1009073] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/21/2021] [Accepted: 05/12/2021] [Indexed: 11/18/2022] Open
Abstract
Neurons rely on localized mitochondria to fulfill spatially heterogeneous metabolic demands. Mitochondrial aging occurs on timescales shorter than the neuronal lifespan, necessitating transport of fresh material from the soma. Maintaining an optimal distribution of healthy mitochondria requires an interplay between a stationary pool localized to sites of high metabolic demand and a motile pool capable of delivering new material. Interchange between these pools can occur via transient fusion / fission events or by halting and restarting entire mitochondria. Our quantitative model of neuronal mitostasis identifies key parameters that govern steady-state mitochondrial health at discrete locations. Very infrequent exchange between stationary and motile pools optimizes this system. Exchange via transient fusion allows for robust maintenance, which can be further improved by selective recycling through mitophagy. These results provide a framework for quantifying how perturbations in organelle transport and interactions affect mitochondrial homeostasis in neurons, a key aspect underlying many neurodegenerative disorders.
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Affiliation(s)
- Anamika Agrawal
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
| | - Elena F. Koslover
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
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20
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Synapsin Is Required for Dense Core Vesicle Capture and cAMP-Dependent Neuropeptide Release. J Neurosci 2021; 41:4187-4201. [PMID: 33820857 DOI: 10.1523/jneurosci.2631-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 02/11/2021] [Accepted: 03/09/2021] [Indexed: 11/21/2022] Open
Abstract
Release of neuropeptides from dense core vesicles (DCVs) is essential for neuromodulation. Compared with the release of small neurotransmitters, much less is known about the mechanisms and proteins contributing to neuropeptide release. By optogenetics, behavioral analysis, electrophysiology, electron microscopy, and live imaging, we show that synapsin SNN-1 is required for cAMP-dependent neuropeptide release in Caenorhabditis elegans hermaphrodite cholinergic motor neurons. In synapsin mutants, behaviors induced by the photoactivated adenylyl cyclase bPAC, which we previously showed to depend on ACh and neuropeptides (Steuer Costa et al., 2017), are altered as in animals with reduced cAMP. Synapsin mutants have slight alterations in synaptic vesicle (SV) distribution; however, a defect in SV mobilization was apparent after channelrhodopsin-based photostimulation. DCVs were largely affected in snn-1 mutants: DCVs were ∼30% reduced in synaptic terminals, and their contents not released following bPAC stimulation. Imaging axonal DCV trafficking, also in genome-engineered mutants in the serine-9 protein kinase A phosphorylation site, showed that synapsin captures DCVs at synapses, making them available for release. SNN-1 colocalized with immobile, captured DCVs. In synapsin deletion mutants, DCVs were more mobile and less likely to be caught at release sites, and in nonphosphorylatable SNN-1B(S9A) mutants, DCVs traffic less and accumulate, likely by enhanced SNN-1 dependent tethering. Our work establishes synapsin as a key mediator of neuropeptide release.SIGNIFICANCE STATEMENT Little is known about mechanisms that regulate how neuropeptide-containing dense core vesicles (DCVs) traffic along the axon, how neuropeptide release is orchestrated, and where it occurs. We found that one of the longest known synaptic proteins, required for the regulation of synaptic vesicles and their storage in nerve terminals, synapsin, is also essential for neuropeptide release. By electrophysiology, imaging, and electron microscopy in Caenorhabditis elegans, we show that synapsin regulates this process by tethering the DCVs to the cytoskeleton in axonal regions where neuropeptides are to be released. Without synapsin, DCVs cannot be captured at the release sites and, consequently, cannot fuse with the membrane, and neuropeptides are not released. We suggest that synapsin fulfills this role also in vertebrates, including humans.
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21
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Aiken J, Holzbaur ELF. Cytoskeletal regulation guides neuronal trafficking to effectively supply the synapse. Curr Biol 2021; 31:R633-R650. [PMID: 34033795 DOI: 10.1016/j.cub.2021.02.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The development and proper function of the brain requires the formation of highly complex neuronal circuitry. These circuits are shaped from synaptic connections between neurons and must be maintained over a lifetime. The formation and continued maintenance of synapses requires accurate trafficking of presynaptic and postsynaptic components along the axon and dendrite, respectively, necessitating deliberate and specialized delivery strategies to replenish essential synaptic components. Maintenance of synaptic transmission also requires readily accessible energy stores, produced in part by localized mitochondria, that are tightly regulated with activity level. In this review, we focus on recent developments in our understanding of the cytoskeletal environment of axons and dendrites, examining how local regulation of cytoskeletal dynamics and organelle trafficking promotes synapse-specific delivery and plasticity. These new insights shed light on the complex and coordinated role that cytoskeletal elements play in establishing and maintaining neuronal circuitry.
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Affiliation(s)
- Jayne Aiken
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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22
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Moro A, van Nifterick A, Toonen RF, Verhage M. Dynamin controls neuropeptide secretion by organizing dense-core vesicle fusion sites. SCIENCE ADVANCES 2021; 7:7/21/eabf0659. [PMID: 34020952 PMCID: PMC8139595 DOI: 10.1126/sciadv.abf0659] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 04/02/2021] [Indexed: 05/13/2023]
Abstract
Synaptic vesicles (SVs) release neurotransmitters at specialized active zones, but release sites and organizing principles for the other major secretory pathway, neuropeptide/neuromodulator release from dense-core vesicles (DCVs), remain elusive. We identify dynamins, yeast Vps1 orthologs, as DCV fusion site organizers in mammalian neurons. Genetic or pharmacological inactivation of all three dynamins strongly impaired DCV exocytosis, while SV exocytosis remained unaffected. Wild-type dynamin restored normal exocytosis but not guanosine triphosphatase-deficient or membrane-binding mutants that cause neurodevelopmental syndromes. During prolonged stimulation, repeated use of the same DCV fusion location was impaired in dynamin 1-3 triple knockout neurons. The syntaxin-1 staining efficiency, but not its expression level, was reduced. αSNAP (α-soluble N-ethylmaleimide-sensitive factor attachment protein) expression restored this. We conclude that mammalian dynamins organize DCV fusion sites, downstream of αSNAP, by regulating the equilibrium between fusogenic and non-fusogenic syntaxin-1 promoting its availability for SNARE (SNAP receptor) complex formation and DCV exocytosis.
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Affiliation(s)
- Alessandro Moro
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Amsterdam Neuroscience, VU University Medical Center, Amsterdam, Netherlands
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands
| | - Anne van Nifterick
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands
| | - Ruud F Toonen
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands.
| | - Matthijs Verhage
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Amsterdam Neuroscience, VU University Medical Center, Amsterdam, Netherlands.
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Vrije Universiteit (VU) Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands
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23
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Temporally and spatially partitioned neuropeptide release from individual clock neurons. Proc Natl Acad Sci U S A 2021; 118:2101818118. [PMID: 33875606 DOI: 10.1073/pnas.2101818118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Neuropeptides control rhythmic behaviors, but the timing and location of their release within circuits is unknown. Here, imaging in the brain shows that synaptic neuropeptide release by Drosophila clock neurons is diurnal, peaking at times of day that were not anticipated by prior electrical and Ca2+ data. Furthermore, hours before peak synaptic neuropeptide release, neuropeptide release occurs at the soma, a neuronal compartment that has not been implicated in peptidergic transmission. The timing disparity between release at the soma and terminals results from independent and compartmentalized mechanisms for daily rhythmic release: consistent with conventional electrical activity-triggered synaptic transmission, terminals require Ca2+ influx, while somatic neuropeptide release is triggered by the biochemical signal IP3 Upon disrupting the somatic mechanism, the rhythm of terminal release and locomotor activity period are unaffected, but the number of flies with rhythmic behavior and sleep-wake balance are reduced. These results support the conclusion that somatic neuropeptide release controls specific features of clock neuron-dependent behaviors. Thus, compartment-specific mechanisms within individual clock neurons produce temporally and spatially partitioned neuropeptide release to expand the peptidergic connectome underlying daily rhythmic behaviors.
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24
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Perrone-Capano C, Volpicelli F, Penna E, Chun JT, Crispino M. Presynaptic protein synthesis and brain plasticity: From physiology to neuropathology. Prog Neurobiol 2021; 202:102051. [PMID: 33845165 DOI: 10.1016/j.pneurobio.2021.102051] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 03/14/2021] [Accepted: 04/07/2021] [Indexed: 12/12/2022]
Abstract
To form and maintain extremely intricate and functional neural circuitry, mammalian neurons are typically endowed with highly arborized dendrites and a long axon. The synapses that link neurons to neurons or to other cells are numerous and often too remote for the cell body to make and deliver new proteins to the right place in time. Moreover, synapses undergo continuous activity-dependent changes in their number and strength, establishing the basis of neural plasticity. The innate dilemma is then how a highly complex neuron provides new proteins for its cytoplasmic periphery and individual synapses to support synaptic plasticity. Here, we review a growing body of evidence that local protein synthesis in discrete sites of the axon and presynaptic terminals plays crucial roles in synaptic plasticity, and that deregulation of this local translation system is implicated in various pathologies of the nervous system.
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Affiliation(s)
- Carla Perrone-Capano
- Department of Pharmacy, University of Naples Federico II, Naples, Italy; Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR, Naples, Italy.
| | | | - Eduardo Penna
- Department of Biology, University of Naples Federico II, Naples, Italy.
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy.
| | - Marianna Crispino
- Department of Biology, University of Naples Federico II, Naples, Italy.
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25
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Lund VK, Lycas MD, Schack A, Andersen RC, Gether U, Kjaerulff O. Rab2 drives axonal transport of dense core vesicles and lysosomal organelles. Cell Rep 2021; 35:108973. [PMID: 33852866 DOI: 10.1016/j.celrep.2021.108973] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 02/10/2021] [Accepted: 03/19/2021] [Indexed: 12/18/2022] Open
Abstract
Fast axonal transport of neuropeptide-containing dense core vesicles (DCVs), endolysosomal organelles, and presynaptic components is critical for maintaining neuronal functionality. How the transport of DCVs is orchestrated remains an important unresolved question. The small GTPase Rab2 mediates DCV biogenesis and endosome-lysosome fusion. Here, we use Drosophila to demonstrate that Rab2 also plays a critical role in bidirectional axonal transport of DCVs, endosomes, and lysosomal organelles, most likely by controlling molecular motors. We further show that the lysosomal motility factor Arl8 is required as well for axonal transport of DCVs, but unlike Rab2, it is also critical for DCV exit from cell bodies into axons. We also provide evidence that the upstream regulators of Rab2 and Arl8, Ema and BORC, activate these GTPases during DCV transport. Our results uncover the mechanisms underlying axonal transport of DCVs and reveal surprising parallels between the regulation of DCV and lysosomal motility.
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Affiliation(s)
- Viktor Karlovich Lund
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Matthew Domenic Lycas
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Anders Schack
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Rita Chan Andersen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Ulrik Gether
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Ole Kjaerulff
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark.
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Neuromodulation Can Be Simple: Myoinhibitory Peptide, Contained in Dedicated Regulatory Pathways, Is the Only Neurally-Mediated Peptide Modulator of Stick Insect Leg Muscle. J Neurosci 2021; 41:2911-2929. [PMID: 33531417 DOI: 10.1523/jneurosci.0188-20.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 01/05/2021] [Accepted: 01/12/2021] [Indexed: 01/22/2023] Open
Abstract
In the best studied cases (Aplysia feeding, crustacean stomatogastric system), peptidergic modulation is mediated by large numbers of peptides. Furthermore, in Aplysia, excitatory motor neurons release the peptides, obligatorily coupling target activation and modulator release. Vertebrate nervous systems typically contain about a hundred peptide modulators. These data have created a belief that modulation is, in general, complex. The stick insect leg is a well-studied locomotory model system, and the complete stick insect neuropeptide inventory was recently described. We used multiple techniques to comprehensively examine stick insect leg peptidergic modulation. Single-cell mass spectrometry (MS) and immunohistochemistry showed that myoinhibitory peptide (MIP) is the only neuronal (as opposed to hemolymph-borne) peptide modulator of all leg muscles. Leg muscle excitatory motor neurons contained no neuropeptides. Only the common inhibitor (CI) and dorsal unpaired median (DUM) neuron groups, each neuron of which innervates a group of functionally-related leg muscles, contained MIP. We described MIP transport to, and receptor presence in, one leg muscle, the extensor tibiae (ExtTi). MIP application reduced ExtTi slow fiber force and shortening by about half, increasing the muscle's ability to contract and relax rapidly. These data show neuromodulation does not need to be complex. Excitation and modulation do not need to be obligatorily coupled (Aplysia feeding). Modulation does not need to involve large numbers of peptides, with the attendant possibility of combinatorial explosion (stomatogastric system). Modulation can be simple, mediated by dedicated regulatory neurons, each innervating a single group of functionally-related targets, and all using the same neuropeptide.SIGNIFICANCE STATEMENT Vertebrate and invertebrate nervous systems contain large numbers (around a hundred in human brain) of peptide neurotransmitters. In prior work, neuropeptide modulation has been complex, either obligatorily coupling postsynaptic excitation and modulation, or large numbers of peptides modulating individual neural networks. The complete stick insect neuropeptide inventory was recently described. We comprehensively describe here peptidergic modulation in the stick insect leg. Surprisingly, out of the large number of potential peptide transmitters, only myoinhibitory peptide (MIP) was present in neurons innervating leg muscles. Furthermore, the peptide was present only in dedicated regulatory neurons, not in leg excitatory motor neurons. Peptidergic modulation can thus be simple, neither obligatorily coupling target activation and modulation nor involving so many peptides that combinatorial explosion can occur.
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27
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The vesicle cluster as a major organizer of synaptic composition in the short-term and long-term. Curr Opin Cell Biol 2021; 71:63-68. [PMID: 33706235 DOI: 10.1016/j.ceb.2021.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 01/22/2021] [Accepted: 02/04/2021] [Indexed: 01/29/2023]
Abstract
For decades, the synaptic vesicle cluster has been thought of as a storage space for synaptic vesicles, whose obvious function is to provide vesicles for the depolarization-induced release of neurotransmitters; however, reports over the last few years indicate that the synaptic vesicle cluster probably plays a much broader and more fundamental role in synaptic biology. Various experiments suggest that the cluster is able to regulate protein distribution and mobility in the synapse; moreover, it probably regulates cytoskeleton architecture, mediates the selective removal of synaptic components from the bouton, and controls the responses of the presynapse to plasticity. Here we discuss these features of the vesicle cluster and conclude that it serves as a key organizer of synaptic composition and dynamics.
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29
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Stone MC, Kothe GO, Rolls MM, Jegla T. Cytoskeletal and synaptic polarity of LWamide-like+ ganglion neurons in the sea anemone Nematostella vectensis. J Exp Biol 2020; 223:jeb233197. [PMID: 32968001 PMCID: PMC7673360 DOI: 10.1242/jeb.233197] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 09/14/2020] [Indexed: 12/22/2022]
Abstract
The centralized nervous systems of bilaterian animals rely on directional signaling facilitated by polarized neurons with specialized axons and dendrites. It is not known whether axo-dendritic polarity is exclusive to bilaterians or was already present in early metazoans. We therefore examined neurite polarity in the starlet sea anemone Nematostella vectensis (Cnidaria). Cnidarians form a sister clade to bilaterians and share many neuronal building blocks characteristic of bilaterians, including channels, receptors and synaptic proteins, but their nervous systems comprise a comparatively simple net distributed throughout the body. We developed a tool kit of fluorescent polarity markers for live imaging analysis of polarity in an identified neuron type, large ganglion cells of the body column nerve net that express the LWamide-like neuropeptide. Microtubule polarity differs in bilaterian axons and dendrites, and this in part underlies polarized distribution of cargo to the two types of processes. However, in LWamide-like+ neurons, all neurites had axon-like microtubule polarity suggesting that they may have similar contents. Indeed, presynaptic and postsynaptic markers trafficked to all neurites and accumulated at varicosities where neurites from different neurons often crossed, suggesting the presence of bidirectional synaptic contacts. Furthermore, we could not identify a diffusion barrier in the plasma membrane of any of the neurites like the axon initial segment barrier that separates the axonal and somatodendritic compartments in bilaterian neurons. We conclude that at least one type of neuron in Nematostella vectensis lacks the axo-dendritic polarity characteristic of bilaterian neurons.
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Affiliation(s)
- Michelle C Stone
- Department of Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Gregory O Kothe
- Department of Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Melissa M Rolls
- Department of Biochemistry and Molecular Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Timothy Jegla
- Department of Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
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30
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Abstract
Neuropeptides are important for regulating numerous neural functions and behaviors. Release of neuropeptides requires long-lasting, high levels of cytosolic Ca2+ However, the molecular regulation of neuropeptide release remains to be clarified. Recently, Stac3 was identified as a key regulator of L-type Ca2+ channels (CaChs) and excitation-contraction coupling in vertebrate skeletal muscles. There is a small family of stac genes in vertebrates with other members expressed by subsets of neurons in the central nervous system. The function of neural Stac proteins, however, is poorly understood. Drosophila melanogaster contain a single stac gene, Dstac, which is expressed by muscles and a subset of neurons, including neuropeptide-expressing motor neurons. Here, genetic manipulations, coupled with immunolabeling, Ca2+ imaging, electrophysiology, and behavioral analysis, revealed that Dstac regulates L-type CaChs (Dmca1D) in Drosophila motor neurons and this, in turn, controls the release of neuropeptides.
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31
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S Mogre S, Brown AI, Koslover EF. Getting around the cell: physical transport in the intracellular world. Phys Biol 2020; 17:061003. [PMID: 32663814 DOI: 10.1088/1478-3975/aba5e5] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Eukaryotic cells face the challenging task of transporting a variety of particles through the complex intracellular milieu in order to deliver, distribute, and mix the many components that support cell function. In this review, we explore the biological objectives and physical mechanisms of intracellular transport. Our focus is on cytoplasmic and intra-organelle transport at the whole-cell scale. We outline several key biological functions that depend on physically transporting components across the cell, including the delivery of secreted proteins, support of cell growth and repair, propagation of intracellular signals, establishment of organelle contacts, and spatial organization of metabolic gradients. We then review the three primary physical modes of transport in eukaryotic cells: diffusive motion, motor-driven transport, and advection by cytoplasmic flow. For each mechanism, we identify the main factors that determine speed and directionality. We also highlight the efficiency of each transport mode in fulfilling various key objectives of transport, such as particle mixing, directed delivery, and rapid target search. Taken together, the interplay of diffusion, molecular motors, and flows supports the intracellular transport needs that underlie a broad variety of biological phenomena.
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Affiliation(s)
- Saurabh S Mogre
- Department of Physics, University of California, San Diego, San Diego, California 92093, United States of America
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32
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Talagas M, Lebonvallet N, Leschiera R, Sinquin G, Elies P, Haftek M, Pennec JP, Ressnikoff D, La Padula V, Le Garrec R, L'herondelle K, Mignen O, Le Pottier L, Kerfant N, Reux A, Marcorelles P, Misery L. Keratinocytes Communicate with Sensory Neurons via Synaptic-like Contacts. Ann Neurol 2020; 88:1205-1219. [PMID: 32951274 DOI: 10.1002/ana.25912] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 09/11/2020] [Accepted: 09/11/2020] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Pain, temperature, and itch are conventionally thought to be exclusively transduced by the intraepidermal nerve endings. Although recent studies have shown that epidermal keratinocytes also participate in sensory transduction, the mechanism underlying keratinocyte communication with intraepidermal nerve endings remains poorly understood. We sought to demonstrate the synaptic character of the contacts between keratinocytes and sensory neurons and their involvement in sensory communication between keratinocytes and sensory neurons. METHODS Contacts were explored by morphological, molecular, and functional approaches in cocultures of epidermal keratinocytes and sensory neurons. To interrogate whether structures observed in vitro were also present in the human epidermis, in situ correlative light electron microscopy was performed on human skin biopsies. RESULTS Epidermal keratinocytes dialogue with sensory neurons through en passant synaptic-like contacts. These contacts have the ultrastructural features and molecular hallmarks of chemical synaptic-like contacts: narrow intercellular cleft, keratinocyte synaptic vesicles expressing synaptophysin and synaptotagmin 1, and sensory information transmitted from keratinocytes to sensory neurons through SNARE-mediated (syntaxin1) vesicle release. INTERPRETATION By providing selective communication between keratinocytes and sensory neurons, synaptic-like contacts are the hubs of a 2-site receptor. The permanent epidermal turnover, implying a specific en passant structure and high plasticity, may have delayed their identification, thereby contributing to the long-held concept of nerve endings passing freely between keratinocytes. The discovery of keratinocyte-sensory neuron synaptic-like contacts may call for a reassessment of basic assumptions in cutaneous sensory perception and sheds new light on the pathophysiology of pain and itch as well as the physiology of touch. ANN NEUROL 2020;88:1205-1219.
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Affiliation(s)
- Matthieu Talagas
- Univ Brest, LIEN, Brest University, F-29200 Brest, France.,Department of Pathology, Brest University Hospital, Brest, France.,Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France
| | - Nicolas Lebonvallet
- Univ Brest, LIEN, Brest University, F-29200 Brest, France.,Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France
| | - Raphael Leschiera
- Univ Brest, LIEN, Brest University, F-29200 Brest, France.,Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France
| | - Gerard Sinquin
- Univ Brest, Imagery and Microscopic Measures Facility, Brest University, F-29200 Brest, France
| | - Philippe Elies
- Univ Brest, Imagery and Microscopic Measures Facility, Brest University, F-29200 Brest, France
| | - Marek Haftek
- Laboratory of Tissue Biology and Therapeutic Engineering, University of Lyon 1, UMR 5305 CNRS-UCBL1, Lyon, France
| | - Jean-Pierre Pennec
- Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France.,Univ Brest, Movement Sport and Health (EA1274), Brest University, F-29200 Brest, France
| | - Denis Ressnikoff
- East Lyon Center of Quantitative Imagery, University of Lyon 1, INSERM US 7-CNRS UMS 3453, Lyon, France
| | - Veronica La Padula
- Technological Center of Microstructures, University of Lyon 1, Lyon, France
| | - Raphaele Le Garrec
- Univ Brest, LIEN, Brest University, F-29200 Brest, France.,Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France
| | - Killian L'herondelle
- Univ Brest, LIEN, Brest University, F-29200 Brest, France.,Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France
| | - Olivier Mignen
- Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France.,Univ Brest, INSERM, UMR 1227, Brest University, F-29200 Brest, France
| | - Laetitia Le Pottier
- Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France.,Univ Brest, INSERM, UMR 1227, Brest University, F-29200 Brest, France
| | - Nathalie Kerfant
- Department of Plastic, Reconstructive, and Esthetic Surgery, Brest University Hospital, Brest, France
| | - Alexia Reux
- Univ Brest, LIEN, Brest University, F-29200 Brest, France
| | - Pascale Marcorelles
- Univ Brest, LIEN, Brest University, F-29200 Brest, France.,Department of Pathology, Brest University Hospital, Brest, France.,Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France
| | - Laurent Misery
- Univ Brest, LIEN, Brest University, F-29200 Brest, France.,Univ Brest, Brest Institute of Health Agro Matter, Brest University, F-29200 Brest, France.,Department of Dermatology, Brest University Hospital, Brest, France
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33
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Spinner MA, Pinter K, Drerup CM, Herman TG. A Conserved Role for Vezatin Proteins in Cargo-Specific Regulation of Retrograde Axonal Transport. Genetics 2020; 216:431-445. [PMID: 32788307 PMCID: PMC7536845 DOI: 10.1534/genetics.120.303499] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 07/28/2020] [Indexed: 12/14/2022] Open
Abstract
Active transport of organelles within axons is critical for neuronal health. Retrograde axonal transport, in particular, relays neurotrophic signals received by axon terminals to the nucleus and circulates new material among enpassant synapses. A single motor protein complex, cytoplasmic dynein, is responsible for nearly all retrograde transport within axons: its linkage to and transport of diverse cargos is achieved by cargo-specific regulators. Here, we identify Vezatin as a conserved regulator of retrograde axonal transport. Vertebrate Vezatin (Vezt) is required for the maturation and maintenance of cell-cell junctions and has not previously been implicated in axonal transport. However, a related fungal protein, VezA, has been shown to regulate retrograde transport of endosomes in hyphae. In a forward genetic screen, we identified a loss-of-function mutation in the Drosophila vezatin-like (vezl) gene. We here show that vezl loss prevents a subset of endosomes, including signaling endosomes containing activated BMP receptors, from initiating transport out of motor neuron terminal boutons. vezl loss also decreases the transport of endosomes and dense core vesicles, but not mitochondria, within axon shafts. We disrupted vezt in zebrafish and found that vezt loss specifically impairs the retrograde axonal transport of late endosomes, causing their accumulation in axon terminals. Our work establishes a conserved, cargo-specific role for Vezatin proteins in retrograde axonal transport.
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Affiliation(s)
- Michael A Spinner
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
| | - Katherine Pinter
- Unit on Neuronal Cell Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - Catherine M Drerup
- Unit on Neuronal Cell Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - Tory G Herman
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403
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34
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Kuznetsov IA, Kuznetsov AV. How old are dense-core vesicles residing in en passant boutons: simulation of the mean age of dense-core vesicles in axonal arbours accounting for resident and transiting vesicle populations. Proc Math Phys Eng Sci 2020; 476:20200454. [PMID: 33071588 PMCID: PMC7544361 DOI: 10.1098/rspa.2020.0454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/02/2020] [Indexed: 12/21/2023] Open
Abstract
In neurons, neuropeptides are synthesized in the soma and are then transported along the axon in dense-core vesicles (DCVs). DCVs are captured in varicosities located along the axon terminal called en passant boutons, which are active terminal sites that accumulate and release neurotransmitters. Recently developed experimental techniques allow for the estimation of the age of DCVs in various locations in the axon terminal. Accurate simulation of the mean age of DCVs in boutons requires the development of a model that would account for resident, transiting-anterograde and transiting-retrograde DCV populations. In this paper, such a model is developed. The model is applied to simulating DCV transport in Drosophila type II motoneurons. The model simulates DCV transport and capture in the axon terminals and makes it possible to predict the age density distribution of DCVs in en passant boutons as well as DCV mean age in boutons. The predicted prevalence of older organelles in distal boutons may explain the 'dying back' pattern of axonal degeneration observed in dopaminergic neurons in Parkinson's disease. The predicted difference of two hours between the age of older DCVs residing in distal boutons and the age of younger DCVs residing in proximal boutons is consistent with an approximate estimate of age difference deduced from experimental observations. The age density of resident DCVs is found to be bimodal, which is because DCVs are captured from two transiting states: the anterograde transiting state that contains younger DCVs and the retrograde transiting state that contains older DCVs.
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Affiliation(s)
- Ivan A. Kuznetsov
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrey V. Kuznetsov
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910, USA
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35
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Assembly of the presynaptic active zone. Curr Opin Neurobiol 2020; 63:95-103. [PMID: 32403081 DOI: 10.1016/j.conb.2020.03.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 02/29/2020] [Accepted: 03/18/2020] [Indexed: 12/11/2022]
Abstract
In a presynaptic nerve terminal, the active zone is composed of sophisticated protein machinery that enables secretion on a submillisecond time scale and precisely targets it toward postsynaptic receptors. The past two decades have provided deep insight into the roles of active zone proteins in exocytosis, but we are only beginning to understand how a neuron assembles active zone protein complexes into effective molecular machines. In this review, we outline the fundamental processes that are necessary for active zone assembly and discuss recent advances in understanding assembly mechanisms that arise from genetic, morphological and biochemical studies. We further outline the challenges ahead for understanding this important problem.
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36
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Abstract
The intracellular transport system in neurons is specialized to an extraordinary degree, enabling the delivery of critical cargo to sites in axons or dendrites that are far removed from the cell center. Vesicles formed in the cell body are actively transported by kinesin motors along axonal microtubules to presynaptic sites that can be located more than a meter away. Both growth factors and degradative vesicles carrying aged organelles or aggregated proteins take the opposite route, driven by dynein motors. Distance is not the only challenge; precise delivery of cargos to sites of need must also be accomplished. For example, localized delivery of presynaptic components to hundreds of thousands of "en passant" synapses distributed along the length of a single axon in some neuronal subtypes provides a layer of complexity that must be successfully navigated to maintain synaptic transmission. We review recent advances in the field of axonal transport, with a focus on conceptual developments, and highlight our growing quantitative understanding of neuronal trafficking and its role in maintaining the synaptic function that underlies higher cognitive processes such as learning and memory.
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Affiliation(s)
- Pedro Guedes-Dias
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Institute of Neuronal Cell Biology, Technische Universität München, 80802 Munich, Germany
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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37
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Luo J, Ting CY, Li Y, McQueen P, Lin TY, Hsu CP, Lee CH. Antagonistic regulation by insulin-like peptide and activin ensures the elaboration of appropriate dendritic field sizes of amacrine neurons. eLife 2020; 9:50568. [PMID: 32175842 PMCID: PMC7075694 DOI: 10.7554/elife.50568] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 03/05/2020] [Indexed: 01/09/2023] Open
Abstract
Establishing appropriate sizes and shapes of dendritic arbors is critical for proper wiring of the central nervous system. Here we report that Insulin-like Peptide 2 (DILP2) locally activates transiently expressed insulin receptors in the central dendrites of Drosophila Dm8 amacrine neurons to positively regulate dendritic field elaboration. We found DILP2 was expressed in L5 lamina neurons, which have axonal terminals abutting Dm8 dendrites. Proper Dm8 dendrite morphogenesis and synapse formation required insulin signaling through TOR (target of rapamycin) and SREBP (sterol regulatory element-binding protein), acting in parallel with previously identified negative regulation by Activin signaling to provide robust control of Dm8 dendrite elaboration. A simulation of dendritic growth revealed trade-offs between dendritic field size and robustness when branching and terminating kinetic parameters were constant, but dynamic modulation of the parameters could mitigate these trade-offs. We suggest that antagonistic DILP2 and Activin signals from different afferents appropriately size Dm8 dendritic fields.
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Affiliation(s)
- Jiangnan Luo
- Section on Neuronal Connectivity, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Chun-Yuan Ting
- Section on Neuronal Connectivity, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Yan Li
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Philip McQueen
- Mathematical and Statistical Computing Laboratory, Center for Information Technology, National Institutes of Health, Bethesda, United States
| | - Tzu-Yang Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Chao-Ping Hsu
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China.,Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei, Taiwan, Republic of China
| | - Chi-Hon Lee
- Section on Neuronal Connectivity, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States.,Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, Republic of China
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38
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Lipton DM, Maeder CI, Shen K. Rapid Assembly of Presynaptic Materials behind the Growth Cone in Dopaminergic Neurons Is Mediated by Precise Regulation of Axonal Transport. Cell Rep 2019; 24:2709-2722. [PMID: 30184504 PMCID: PMC6179448 DOI: 10.1016/j.celrep.2018.07.096] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 06/21/2018] [Accepted: 07/27/2018] [Indexed: 11/15/2022] Open
Abstract
The proper assembly of neural circuits depends on the process of synaptogenesis, or the formation of synapses between partner neurons. Using the dopaminergic PDE neurons in C. elegans, we developed an in vivo system to study the earliest steps of the formation of en passant presynaptic specializations behind an extending growth cone. We find that presynaptic materials coalesce into puncta in as little as a few minutes and that both synaptic vesicle (SV) and active zone (AZ) proteins arrive nearly simultaneously at the nascent sites of synapse formation. We show that precise regulation of UNC-104/Kinesin-3 determines the distribution of SV proteins along the axon. The localization of AZ proteins to en passant puncta, however, is largely independent of the major axonal kinesins: UNC-104/Kinesin-3 and UNC-116/ Kinesin-1. Moreover, AZ proteins play a crucial role in recruiting and tethering SV precursors (SVPs). Lipton et al. explore the initial steps of synapse formation in vivo. They find that clustering of major presynaptic material occurs extremely rapidly (<5 min). Both synaptic vesicle precursors and active zone proteins accumulate simultaneously at developing puncta. Precise regulation of the Kinesin-3 activation state strongly influences the positioning of vesicles along the axon during development.
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Affiliation(s)
- David M Lipton
- Howard Hughes Medical Institute, Department of Biology, Stanford University, 385 Serra Mall, Stanford, CA 94305, USA; Neurosciences Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Celine I Maeder
- Howard Hughes Medical Institute, Department of Biology, Stanford University, 385 Serra Mall, Stanford, CA 94305, USA
| | - Kang Shen
- Howard Hughes Medical Institute, Department of Biology, Stanford University, 385 Serra Mall, Stanford, CA 94305, USA.
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39
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Abstract
Synaptic release of neuropeptides packaged in dense-core vesicles (DCVs) regulates synapses, circuits, and behaviors including feeding, sleeping, and pain perception. Here, synaptic DCV fusion pore openings are imaged without interference from cotransmitting small synaptic vesicles (SSVs) with the use of a fluorogen-activating protein (FAP). Activity-evoked kiss and run exocytosis opens synaptic DCV fusion pores away from active zones that readily conduct molecules larger than most native neuropeptides (i.e., molecular weight [MW] up to, at least, 4.5 kDa). Remarkably, these synaptic fusion pores also open spontaneously in the absence of stimulation and extracellular Ca2+ SNARE perturbations demonstrate different mechanisms for activity-evoked and spontaneous fusion pore openings with the latter sharing features of spontaneous small molecule transmitter release by active zone-associated SSVs. Fusion pore opening at resting synapses provides a mechanism for activity-independent peptidergic transmission.
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40
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Kuznetsov IA, Kuznetsov AV. Modelling transport and mean age of dense core vesicles in large axonal arbours. Proc Math Phys Eng Sci 2019; 475:20190284. [PMID: 31534430 PMCID: PMC6735487 DOI: 10.1098/rspa.2019.0284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 07/19/2019] [Indexed: 10/14/2023] Open
Abstract
A model simulating the transport of dense core vesicles (DCVs) in type II axonal terminals of Drosophila motoneurons has been developed. The morphology of type II terminals is characterized by the large number of en passant boutons. The lack of both scaled-up DCV transport and scaled-down DCV capture in boutons results in a less efficient supply of DCVs to distal boutons. Furthermore, the large number of boutons that DCVs pass as they move anterogradely until they reach the most distal bouton may lead to the capture of a majority of DCVs before they turn around in the most distal bouton to move in the retrograde direction. This may lead to a reduced retrograde flux of DCVs and a lack of DCV circulation in type II terminals. The developed model simulates DCV concentrations in boutons, DCV fluxes between the boutons, age density distributions of DCVs and the mean age of DCVs in various boutons. Unlike published experimental observations, our model predicts DCV circulation in type II terminals after these terminals are filled to saturation. This disagreement is likely because experimentally observed terminals were not at steady state, but rather were accumulating DCVs for later release. Our estimates show that the number of DCVs in the transiting state is much smaller than that in the resident state. DCVs travelling in the axon, rather than DCVs transiting in the terminal, may provide a reserve of DCVs for replenishing boutons after a release. The techniques for modelling transport of DCVs developed in our paper can be used to model the transport of other organelles in axons.
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Affiliation(s)
- I. A. Kuznetsov
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - A. V. Kuznetsov
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910, USA
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41
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Tao J, Bulgari D, Berkhoudt DA, Calderon MJ, Watkins SC, Fonseca Velez HJ, Sabeva N, Deitcher DL, Levitan ES. Drosophila Ptp4E regulates vesicular packaging for monoamine-neuropeptide co-transmission. J Cell Sci 2019; 132:jcs.224568. [PMID: 30837287 DOI: 10.1242/jcs.224568] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 02/25/2019] [Indexed: 12/12/2022] Open
Abstract
Many neurons influence their targets through co-release of neuropeptides and small-molecule transmitters. Neuropeptides are packaged into dense-core vesicles (DCVs) in the soma and then transported to synapses, while small-molecule transmitters such as monoamines are packaged by vesicular transporters that function at synapses. These separate packaging mechanisms point to activity, by inducing co-release as the sole scaler of co-transmission. Based on screening in Drosophila for increased presynaptic neuropeptides, the receptor protein tyrosine phosphatase (Rptp) Ptp4E was found to post-transcriptionally regulate neuropeptide content in single DCVs at octopamine synapses. This occurs without changing neuropeptide release efficiency, transport and DCV size measured by both stimulated emission depletion super-resolution and transmission electron microscopy. Ptp4E also controls the presynaptic abundance and activity of the vesicular monoamine transporter (VMAT), which packages monoamine transmitters for synaptic release. Thus, rather than rely on altering electrical activity, the Rptp regulates packaging underlying monoamine-neuropeptide co-transmission by controlling vesicular membrane transporter and luminal neuropeptide content.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Juan Tao
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Dinara Bulgari
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Drew A Berkhoudt
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Michael J Calderon
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Simon C Watkins
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Hector J Fonseca Velez
- Department of Neuroscience, Universidad Central del Caribe, Bayamón, Puerto Rico 00960, USA
| | - Nadezhda Sabeva
- Department of Neuroscience, Universidad Central del Caribe, Bayamón, Puerto Rico 00960, USA
| | - David L Deitcher
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Edwin S Levitan
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
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42
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Guedes-Dias P, Nirschl JJ, Abreu N, Tokito MK, Janke C, Magiera MM, Holzbaur ELF. Kinesin-3 Responds to Local Microtubule Dynamics to Target Synaptic Cargo Delivery to the Presynapse. Curr Biol 2019; 29:268-282.e8. [PMID: 30612907 DOI: 10.1016/j.cub.2018.11.065] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 11/08/2018] [Accepted: 11/28/2018] [Indexed: 01/05/2023]
Abstract
Neurons in the CNS establish thousands of en passant synapses along their axons. Robust neurotransmission depends on the replenishment of synaptic components in a spatially precise manner. Using live-cell microscopy and single-molecule reconstitution assays, we find that the delivery of synaptic vesicle precursors (SVPs) to en passant synapses in hippocampal neurons is specified by an interplay between the kinesin-3 KIF1A motor and presynaptic microtubules. Presynaptic sites are hotspots of dynamic microtubules rich in GTP-tubulin. KIF1A binds more weakly to GTP-tubulin than GDP-tubulin and competes with end-binding (EB) proteins for binding to the microtubule plus end. A disease-causing mutation within KIF1A that reduces preferential binding to GDP- versus GTP-rich microtubules disrupts SVP delivery and reduces presynaptic release upon neuronal stimulation. Thus, the localized enrichment of dynamic microtubules along the axon specifies a localized unloading zone that ensures the accurate delivery of SVPs, controlling presynaptic strength in hippocampal neurons.
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Affiliation(s)
- Pedro Guedes-Dias
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA; The Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
| | - Jeffrey J Nirschl
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA; The Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
| | - Nohely Abreu
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA; The Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
| | - Mariko K Tokito
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
| | - Carsten Janke
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay, France; Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Maria M Magiera
- Institut Curie, PSL Research University, CNRS UMR3348, Orsay, France; Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, Orsay, France
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA; The Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA.
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43
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Banerjee S, Riordan M. Coordinated Regulation of Axonal Microtubule Organization and Transport by Drosophila Neurexin and BMP Pathway. Sci Rep 2018; 8:17337. [PMID: 30478335 PMCID: PMC6255869 DOI: 10.1038/s41598-018-35618-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/07/2018] [Indexed: 01/23/2023] Open
Abstract
Neurexins are well known trans-synaptic cell adhesion molecules that are required for proper synaptic development and function across species. Beyond synapse organization and function, little is known about other roles Neurexins might have in the nervous system. Here we report novel phenotypic consequences of mutations in Drosophila neurexin (dnrx), which alters axonal microtubule organization and transport. We show that dnrx mutants display phenotypic similarities with the BMP receptor wishful thinking (wit) and one of the downstream effectors, futsch, which is a known regulator of microtubule organization and stability. dnrx has genetic interactions with wit and futsch. Loss of Dnrx also results in reduced levels of other downstream effectors of BMP signaling, phosphorylated-Mad and Trio. Interestingly, postsynaptic overexpression of the BMP ligand, Glass bottom boat, in dnrx mutants partially rescues the axonal transport defects but not the synapse undergrowth at the neuromuscular junctions. These data suggest that Dnrx and BMP signaling are involved in many diverse functions and that regulation of axonal MT organization and transport might be distinct from regulation of synaptic growth in dnrx mutants. Together, our work uncovers a novel function of Drosophila Neurexin and may provide insights into functions of Neurexins in vertebrates.
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Affiliation(s)
- Swati Banerjee
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA.
| | - Maeveen Riordan
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA.,University of Colorado School of Medicine, 12631 E. 17th Avenue B177, Aurora, CO, 80045, USA
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44
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Morrison LM, Edwards SL, Manning L, Stec N, Richmond JE, Miller KG. Sentryn and SAD Kinase Link the Guided Transport and Capture of Dense Core Vesicles in Caenorhabditis elegans. Genetics 2018; 210:925-946. [PMID: 30401764 PMCID: PMC6218223 DOI: 10.1534/genetics.118.300847] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 08/27/2018] [Indexed: 11/18/2022] Open
Abstract
Dense core vesicles (DCVs) can transmit signals by releasing neuropeptides from specialized synaptic regions called active zones. DCVs reach the active zone by motorized transport through a long axon. A reverse motor frequently interrupts progress by taking DCVs in the opposite direction. "Guided transport" refers to the mechanism by which outward movements ultimately dominate to bring DCVs to the synaptic region. After guided transport, DCVs alter their interactions with motors and enter a "captured" state. The mechanisms of guided transport and capture of DCVs are unknown. Here, we discovered two proteins that contribute to both processes in Caenorhabditis elegans SAD kinase and a novel conserved protein we named Sentryn are the first proteins found to promote DCV capture. By imaging DCVs moving in various regions of single identified neurons in living animals, we found that DCV guided transport and capture are linked through SAD kinase, Sentryn, and Liprin-α. These proteins act together to regulate DCV motorized transport in a region-specific manner. Between the cell body and the synaptic region, they promote forward transport. In the synaptic region, where all three proteins are highly enriched at active zones, they promote DCV pausing by inhibiting transport in both directions. These three proteins appear to be part of a special subset of active zone-enriched proteins because other active zone proteins do not share their unique functions.
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Affiliation(s)
- Logan M Morrison
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma 73104
| | - Stacey L Edwards
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma 73104
| | - Laura Manning
- Department of Biological Sciences, University of Illinois at Chicago, Illinois 60607
| | - Natalia Stec
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma 73104
| | - Janet E Richmond
- Department of Biological Sciences, University of Illinois at Chicago, Illinois 60607
| | - Kenneth G Miller
- Genetic Models of Disease Laboratory, Oklahoma Medical Research Foundation, Oklahoma 73104
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Persoon CM, Moro A, Nassal JP, Farina M, Broeke JH, Arora S, Dominguez N, van Weering JR, Toonen RF, Verhage M. Pool size estimations for dense-core vesicles in mammalian CNS neurons. EMBO J 2018; 37:e99672. [PMID: 30185408 PMCID: PMC6187028 DOI: 10.15252/embj.201899672] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 08/08/2018] [Accepted: 08/08/2018] [Indexed: 01/03/2023] Open
Abstract
Neuropeptides are essential signaling molecules transported and secreted by dense-core vesicles (DCVs), but the number of DCVs available for secretion, their subcellular distribution, and release probability are unknown. Here, we quantified DCV pool sizes in three types of mammalian CNS neurons in vitro and in vivo Super-resolution and electron microscopy reveal a total pool of 1,400-18,000 DCVs, correlating with neurite length. Excitatory hippocampal and inhibitory striatal neurons in vitro have a similar DCV density, and thalamo-cortical axons in vivo have a slightly higher density. Synapses contain on average two to three DCVs, at the periphery of synaptic vesicle clusters. DCVs distribute equally in axons and dendrites, but the vast majority (80%) of DCV fusion events occur at axons. The release probability of DCVs is 1-6%, depending on the stimulation. Thus, mammalian CNS neurons contain a large pool of DCVs of which only a small fraction can fuse, preferentially at axons.
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Affiliation(s)
| | - Alessandro Moro
- Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands
| | - Joris P Nassal
- Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands
| | - Margherita Farina
- Department of Functional Genomics, Faculty of Exact Science, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, Amsterdam, The Netherlands
| | - Jurjen H Broeke
- Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands
| | - Swati Arora
- Department of Functional Genomics, Faculty of Exact Science, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, Amsterdam, The Netherlands
| | | | | | - Ruud F Toonen
- Department of Functional Genomics, Faculty of Exact Science, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, Amsterdam, The Netherlands
| | - Matthijs Verhage
- Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands
- Department of Functional Genomics, Faculty of Exact Science, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, Amsterdam, The Netherlands
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46
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Ormerod KG, Jung J, Mercier AJ. Modulation of neuromuscular synapses and contraction in Drosophila 3rd instar larvae. J Neurogenet 2018; 32:183-194. [PMID: 30303434 DOI: 10.1080/01677063.2018.1502761] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Over the past four decades, Drosophila melanogaster has become an increasingly important model system for studying the modulation of chemical synapses and muscle contraction by cotransmitters and neurohormones. This review describes how advantages provided by Drosophila have been utilized to investigate synaptic modulation, and it discusses key findings from investigations of cotransmitters and neurohormones that act on body wall muscles of 3rd instar Drosophila larvae. These studies have contributed much to our understanding of how neuromuscular systems are modulated by neuropeptides and biogenic amines, but there are still gaps in relating these peripheral modulatory effects to behavior.
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Affiliation(s)
- Kiel G Ormerod
- a Department of Biology , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - JaeHwan Jung
- b Department of Biological Sciences , Brock University , St. Catharines , Canada
| | - A Joffre Mercier
- b Department of Biological Sciences , Brock University , St. Catharines , Canada
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Jung JH, Szule JA, Stouder K, Marshall RM, McMahan UJ. Active Zone Material-Directed Orientation, Docking, and Fusion of Dense Core Vesicles Alongside Synaptic Vesicles at Neuromuscular Junctions. Front Neuroanat 2018; 12:72. [PMID: 30271328 PMCID: PMC6146030 DOI: 10.3389/fnana.2018.00072] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 08/17/2018] [Indexed: 12/13/2022] Open
Abstract
Active zone material is an organelle that is common to active zones along the presynaptic membrane of chemical synapses. Electron tomography on active zones at frog neuromuscular junctions has provided evidence that active zone material directs the docking of synaptic vesicles (SVs) on the presynaptic membrane at this synapse. Certain active zone material macromolecules connect to stereotypically arranged macromolecules in the membrane of undocked SVs, stably orienting a predetermined fusion domain of the vesicle membrane toward the presynaptic membrane while bringing and holding the two membranes together. Docking of the vesicles is required for the impulse-triggered vesicle membrane-presynaptic membrane fusion that releases the vesicles’ neurotransmitter into the synaptic cleft. As at other synapses, axon terminals at frog neuromuscular junctions contain, in addition to SVs, vesicles that are larger, are much less frequent and, when viewed by electron microscopy, have a distinctive electron dense core. Dense core vesicles at neuromuscular junctions are likely to contain peptides that are released into the synaptic cleft to regulate formation, maintenance and behavior of cellular apparatus essential for synaptic impulse transmission. We show by electron tomography on axon terminals of frog neuromuscular junctions fixed at rest and during repetitive impulse transmission that dense core vesicles selectively dock on and fuse with the presynaptic membrane alongside SVs at active zones, and that active zone material connects to the dense core vesicles undergoing these processes in the same way it connects to SVs. We conclude that undocked dense core vesicles have a predetermined fusion domain, as do undocked SVs, and that active zone material directs oriented docking and fusion of these different vesicle types at active zones of the presynaptic membrane by similar macromolecular interactions.
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Affiliation(s)
- Jae H Jung
- Department of Biology, Texas A&M University, College Station, TX, United States.,Department of Neurobiology, Stanford University School of Medicine, Stanford University, Stanford, CA, United States
| | - Joseph A Szule
- Department of Biology, Texas A&M University, College Station, TX, United States.,Department of Neurobiology, Stanford University School of Medicine, Stanford University, Stanford, CA, United States
| | - Kylee Stouder
- Department of Biology, Texas A&M University, College Station, TX, United States
| | - Robert M Marshall
- Department of Biology, Texas A&M University, College Station, TX, United States.,Department of Neurobiology, Stanford University School of Medicine, Stanford University, Stanford, CA, United States
| | - Uel J McMahan
- Department of Biology, Texas A&M University, College Station, TX, United States.,Department of Neurobiology, Stanford University School of Medicine, Stanford University, Stanford, CA, United States
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48
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Presynaptic Biogenesis Requires Axonal Transport of Lysosome-Related Vesicles. Neuron 2018; 99:1216-1232.e7. [DOI: 10.1016/j.neuron.2018.08.004] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 05/18/2018] [Accepted: 08/02/2018] [Indexed: 01/05/2023]
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49
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Emperador-Melero J, Huson V, van Weering J, Bollmann C, Fischer von Mollard G, Toonen RF, Verhage M. Vti1a/b regulate synaptic vesicle and dense core vesicle secretion via protein sorting at the Golgi. Nat Commun 2018; 9:3421. [PMID: 30143604 PMCID: PMC6109172 DOI: 10.1038/s41467-018-05699-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 07/19/2018] [Indexed: 12/27/2022] Open
Abstract
The SNAREs Vti1a/1b are implicated in regulated secretion, but their role relative to canonical exocytic SNAREs remains elusive. Here, we show that synaptic vesicle and dense-core vesicle (DCV) secretion is indeed severely impaired in Vti1a/b-deficient neurons. The synaptic levels of proteins that mediate secretion were reduced, down to 50% for the exocytic SNARE SNAP25. The delivery of SNAP25 and DCV-cargo into axons was decreased and these molecules accumulated in the Golgi. These defects were rescued by either Vti1a or Vti1b expression. Distended Golgi cisternae and clear vacuoles were observed in Vti1a/b-deficient neurons. The normal non-homogeneous distribution of DCV-cargo inside the Golgi was lost. Cargo trafficking out of, but not into the Golgi, was impaired. Finally, retrograde Cholera Toxin trafficking, but not Sortilin/Sorcs1 distribution, was compromised. We conclude that Vti1a/b support regulated secretion by sorting secretory cargo and synaptic secretion machinery components at the Golgi.
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Affiliation(s)
- Javier Emperador-Melero
- Departments of Functional Genomics, Clinical Genetics, VUmc, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam and VU Medical Center, de Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands
| | - Vincent Huson
- Clinical Genetics, VUmc, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam and VU Medical Center, de Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands
| | - Jan van Weering
- Clinical Genetics, VUmc, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam and VU Medical Center, de Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands
| | - Christian Bollmann
- Department of Biochemistry III, Bielefeld University, 33615, Bielefeld, Germany
| | | | - Ruud F Toonen
- Departments of Functional Genomics, Clinical Genetics, VUmc, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam and VU Medical Center, de Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands
| | - Matthijs Verhage
- Departments of Functional Genomics, Clinical Genetics, VUmc, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam and VU Medical Center, de Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands. .,Clinical Genetics, VUmc, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam and VU Medical Center, de Boelelaan 1087, 1081 HV, Amsterdam, The Netherlands.
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50
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Bressloff PC, Maclaurin JN. Stochastic Hybrid Systems in Cellular Neuroscience. JOURNAL OF MATHEMATICAL NEUROSCIENCE 2018; 8:12. [PMID: 30136005 PMCID: PMC6104574 DOI: 10.1186/s13408-018-0067-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 08/05/2018] [Indexed: 06/08/2023]
Abstract
We review recent work on the theory and applications of stochastic hybrid systems in cellular neuroscience. A stochastic hybrid system or piecewise deterministic Markov process involves the coupling between a piecewise deterministic differential equation and a time-homogeneous Markov chain on some discrete space. The latter typically represents some random switching process. We begin by summarizing the basic theory of stochastic hybrid systems, including various approximation schemes in the fast switching (weak noise) limit. In subsequent sections, we consider various applications of stochastic hybrid systems, including stochastic ion channels and membrane voltage fluctuations, stochastic gap junctions and diffusion in randomly switching environments, and intracellular transport in axons and dendrites. Finally, we describe recent work on phase reduction methods for stochastic hybrid limit cycle oscillators.
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