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Wei L, Guo X, Haimov E, Obashi K, Lee SH, Shin W, Sun M, Chan CY, Sheng J, Zhang Z, Mohseni A, Ghosh Dastidar S, Wu XS, Wang X, Han S, Arpino G, Shi B, Molakarimi M, Matthias J, Wurm CA, Gan L, Taraska JW, Kozlov MM, Wu LG. Clathrin mediates membrane fission and budding by constricting membrane pores. Cell Discov 2024; 10:62. [PMID: 38862506 PMCID: PMC11166961 DOI: 10.1038/s41421-024-00677-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 04/04/2024] [Indexed: 06/13/2024] Open
Abstract
Membrane budding, which underlies fundamental processes like endocytosis, intracellular trafficking, and viral infection, is thought to involve membrane coat-forming proteins, including the most observed clathrin, to form Ω-shape profiles and helix-forming proteins like dynamin to constrict Ω-profiles' pores and thus mediate fission. Challenging this fundamental concept, we report that polymerized clathrin is required for Ω-profiles' pore closure and that clathrin around Ω-profiles' base/pore region mediates pore constriction/closure in neuroendocrine chromaffin cells. Mathematical modeling suggests that clathrin polymerization at Ω-profiles' base/pore region generates forces from its intrinsically curved shape to constrict/close the pore. This new fission function may exert broader impacts than clathrin's well-known coat-forming function during clathrin (coat)-dependent endocytosis, because it underlies not only clathrin (coat)-dependent endocytosis, but also diverse endocytic modes, including ultrafast, fast, slow, bulk, and overshoot endocytosis previously considered clathrin (coat)-independent in chromaffin cells. It mediates kiss-and-run fusion (fusion pore closure) previously considered bona fide clathrin-independent, and limits the vesicular content release rate. Furthermore, analogous to results in chromaffin cells, we found that clathrin is essential for fast and slow endocytosis at hippocampal synapses where clathrin was previously considered dispensable, suggesting clathrin in mediating synaptic vesicle endocytosis and fission. These results suggest that clathrin and likely other intrinsically curved coat proteins are a new class of fission proteins underlying vesicle budding and fusion. The half-a-century concept and studies that attribute vesicle-coat contents' function to Ω-profile formation and classify budding as coat-protein (e.g., clathrin)-dependent or -independent may need to be re-defined and re-examined by considering clathrin's pivotal role in pore constriction/closure.
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Affiliation(s)
- Lisi Wei
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Xiaoli Guo
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Ehud Haimov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel
| | - Kazuki Obashi
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - Sung Hoon Lee
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- Chung-Ang University, Seoul, Republic of Korea
| | - Wonchul Shin
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Min Sun
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Chung Yu Chan
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Jiansong Sheng
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- 900 Clopper Rd, Suite, 130, Gaithersburg, MD, USA
| | - Zhen Zhang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- Center of Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Ammar Mohseni
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | | | - Xin-Sheng Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Xin Wang
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Sue Han
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
- Emme 3 Srl - Via Luigi Meraviglia, 31 - 20020, Lainate, MI, Italy
| | - Bo Shi
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Maryam Molakarimi
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | | | | | - Lin Gan
- Department of Neuroscience & Regenerative Medicine, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel.
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
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Jain S, Yee AG, Maas J, Gierok S, Xu H, Stansil J, Eriksen J, Nelson AB, Silm K, Ford CP, Edwards RH. Adaptor protein-3 produces synaptic vesicles that release phasic dopamine. Proc Natl Acad Sci U S A 2023; 120:e2309843120. [PMID: 37812725 PMCID: PMC10589613 DOI: 10.1073/pnas.2309843120] [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: 06/12/2023] [Accepted: 09/06/2023] [Indexed: 10/11/2023] Open
Abstract
The burst firing of midbrain dopamine neurons releases a phasic dopamine signal that mediates reinforcement learning. At many synapses, however, high firing rates deplete synaptic vesicles (SVs), resulting in synaptic depression that limits release. What accounts for the increased release of dopamine by stimulation at high frequency? We find that adaptor protein-3 (AP-3) and its coat protein VPS41 promote axonal dopamine release by targeting vesicular monoamine transporter VMAT2 to the axon rather than dendrites. AP-3 and VPS41 also produce SVs that respond preferentially to high-frequency stimulation, independent of their role in axonal polarity. In addition, conditional inactivation of VPS41 in dopamine neurons impairs reinforcement learning, and this involves a defect in the frequency dependence of release rather than the amount of dopamine released. Thus, AP-3 and VPS41 promote the axonal polarity of dopamine release but enable learning by producing a distinct population of SVs tuned specifically to high firing frequency that confers the phasic release of dopamine.
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Affiliation(s)
- Shweta Jain
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Andrew G. Yee
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO80045
| | - James Maas
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Sarah Gierok
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Hongfei Xu
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Jasmine Stansil
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Jacob Eriksen
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Alexandra B. Nelson
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
- Aligning Science Across Parkinson’s Collaborative Research Network, Chevy Chase, MD20815
| | - Katlin Silm
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
| | - Christopher P. Ford
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO80045
- Aligning Science Across Parkinson’s Collaborative Research Network, Chevy Chase, MD20815
| | - Robert H. Edwards
- Department of Physiology, University of California School of Medicine, San Francisco, CA94143
- Department of Neurology, University of California School of Medicine, San Francisco, CA94143
- Aligning Science Across Parkinson’s Collaborative Research Network, Chevy Chase, MD20815
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Towers EB, Shapiro DA, Abel JM, Bakhti-Suroosh A, Kupkova K, Auble DT, Grant PA, Lynch WJ. Transcriptional Profile of Exercise-Induced Protection Against Relapse to Cocaine Seeking in a Rat Model. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2023; 3:734-745. [PMID: 37881559 PMCID: PMC10593899 DOI: 10.1016/j.bpsgos.2023.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/23/2023] [Accepted: 01/25/2023] [Indexed: 02/05/2023] Open
Abstract
Background Exercise has shown promise as a treatment for cocaine use disorder; however, the mechanism underlying its efficacy has remained elusive. Methods We used a rat model of relapse (cue-induced reinstatement) and exercise (wheel running, 2 hours/day) coupled with RNA sequencing to establish transcriptional profiles associated with the protective effects of exercise (during early withdrawal [days 1-7] or throughout withdrawal [days 1-14]) versus noneffective exercise (during late withdrawal [days 8-14]) against cocaine-seeking and sedentary conditions. Results As expected, cue-induced cocaine seeking was highest in the sedentary and late-withdrawal exercise groups; both groups also showed upregulation of a Grin1-associated transcript and enrichment of Drd1-Nmdar1 complex and glutamate receptor complex terms. Surprisingly, these glutamate markers were also enriched in the early- and throughout-withdrawal exercise groups, despite lower levels of cocaine seeking. However, a closer examination of the Grin1-associated transcript revealed a robust loss of transcripts spanning exons 9 and 10 in the sedentary condition relative to saline controls that was normalized by early- and throughout-withdrawal exercise, but not late-withdrawal exercise, indicating that these exercise conditions may normalize RNA mis-splicing induced by cocaine seeking. Our findings also revealed novel mechanisms by which exercise initiated during early withdrawal may modulate glutamatergic signaling in dorsomedial prefrontal cortex (e.g., via transcripts associated with non-NMDA glutamate receptors or those affecting signaling downstream of NMDA receptors), along with mechanisms outside of glutamatergic signaling such as circadian rhythm regulation and neuronal survival. Conclusions These findings provide a rich resource for future studies aimed at manipulating these molecular networks to better understand how exercise decreases cocaine seeking.
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Affiliation(s)
- Eleanor Blair Towers
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
- Medical Scientist Training Program, University of Virginia, Charlottesville, Virginia
| | - Daniel A. Shapiro
- Center for Brain Immunology and Glia, Department of Neuroscience, University of Virginia, Charlottesville, Virginia
| | - Jean M. Abel
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
| | - Anousheh Bakhti-Suroosh
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
| | - Kristyna Kupkova
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia
| | - David T. Auble
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia
| | - Patrick A. Grant
- Department of Biomedical Science, Florida Atlantic University, Boca Raton, Florida
| | - Wendy J. Lynch
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, Virginia
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Jain S, Yee AG, Maas J, Gierok S, Xu H, Stansil J, Eriksen J, Nelson A, Silm K, Ford CP, Edwards RH. Adaptor Protein-3 Produces Synaptic Vesicles that Release Phasic Dopamine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.07.552338. [PMID: 37609166 PMCID: PMC10441354 DOI: 10.1101/2023.08.07.552338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The burst firing of midbrain dopamine neurons releases a phasic dopamine signal that mediates reinforcement learning. At many synapses, however, high firing rates deplete synaptic vesicles (SVs), resulting in synaptic depression that limits release. What accounts for the increased release of dopamine by stimulation at high frequency? We find that adaptor protein-3 (AP-3) and its coat protein VPS41 promote axonal dopamine release by targeting vesicular monoamine transporter VMAT2 to the axon rather than dendrites. AP-3 and VPS41 also produce SVs that respond preferentially to high frequency stimulation, independent of their role in axonal polarity. In addition, conditional inactivation of VPS41 in dopamine neurons impairs reinforcement learning, and this involves a defect in the frequency dependence of release rather than the amount of dopamine released. Thus, AP-3 and VPS41 promote the axonal polarity of dopamine release but enable learning by producing a novel population of SVs tuned specifically to high firing frequency that confers the phasic release of dopamine.
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Affiliation(s)
- Shweta Jain
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Andrew G. Yee
- Department of Pharmacology, University of Colorado School of Medicine, Aurora USA
| | - James Maas
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Sarah Gierok
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Hongfei Xu
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Jasmine Stansil
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Jacob Eriksen
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Alexandra Nelson
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Katlin Silm
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
| | - Christopher P. Ford
- Department of Pharmacology, University of Colorado School of Medicine, Aurora USA
| | - Robert H. Edwards
- Department of Physiology, UCSF School of Medicine, San Francisco USA
- Department of Neurology, UCSF School of Medicine, San Francisco USA
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5
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Cook DC, Ryan TA. GABA BR silencing of nerve terminals. eLife 2023; 12:e83530. [PMID: 37014052 PMCID: PMC10115440 DOI: 10.7554/elife.83530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 04/03/2023] [Indexed: 04/05/2023] Open
Abstract
Control of neurotransmission efficacy is central to theories of how the brain computes and stores information. Presynaptic G-protein coupled receptors (GPCRs) are critical in this problem as they locally influence synaptic strength and can operate on a wide range of time scales. Among the mechanisms by which GPCRs impact neurotransmission is by inhibiting voltage-gated calcium (Ca2+) influx in the active zone. Here, using quantitative analysis of both single bouton Ca2+ influx and exocytosis, we uncovered an unexpected non-linear relationship between the magnitude of action potential driven Ca2+ influx and the concentration of external Ca2+ ([Ca2+]e). We find that this unexpected relationship is leveraged by GPCR signaling when operating at the nominal physiological set point for [Ca2+]e, 1.2 mM, to achieve complete silencing of nerve terminals. These data imply that the information throughput in neural circuits can be readily modulated in an all-or-none fashion at the single synapse level when operating at the physiological set point.
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Affiliation(s)
- Daniel C Cook
- Department of Anesthesiology, Weill Cornell Medical CollegeNew YorkUnited States
| | - Timothy A Ryan
- Department of Anesthesiology, Weill Cornell Medical CollegeNew YorkUnited States
- Department of Biochemistry, Weill Cornell Medical CollegeNew YorkUnited States
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6
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Krishnan S, Klingauf J. The readily retrievable pool of synaptic vesicles. Biol Chem 2023; 404:385-397. [PMID: 36867726 DOI: 10.1515/hsz-2022-0298] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/16/2023] [Indexed: 03/05/2023]
Abstract
In the CNS communication between neurons occurs at synapses by secretion of neurotransmitter via exocytosis of synaptic vesicles (SVs) at the active zone. Given the limited number of SVs in presynaptic boutons a fast and efficient recycling of exocytosed membrane and proteins by triggered compensatory endocytosis is required to maintain neurotransmission. Thus, pre-synapses feature a unique tight coupling of exo- and endocytosis in time and space resulting in the reformation of SVs with uniform morphology and well-defined molecular composition. This rapid response requires early stages of endocytosis at the peri-active zone to be well choreographed to ensure reformation of SVs with high fidelity. The pre-synapse can address this challenge by a specialized membrane microcompartment, where a pre-sorted and pre-assembled readily retrievable pool (RRetP) of endocytic membrane patches is formed, consisting of the vesicle cargo, presumably bound within a nucleated Clathrin and adaptor complex. This review considers evidence for the RRetP microcompartment to be the primary organizer of presynaptic triggered compensatory endocytosis.
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Affiliation(s)
- Sai Krishnan
- Institute of Medical Physics and Biophysics, University of Münster, Robert-Koch Strasse 31, D-48149, Münster, Germany
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, University of Münster, Robert-Koch Strasse 31, D-48149, Münster, Germany.,Center for Soft Nanoscience, Busso-Peus Strasse 10, D-48149, Münster, Germany
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Cerium-Doped Self-Assembling Nanoparticles as a Novel Anti-Oxidant Delivery System Preserving Mitochondrial Function in Cortical Neurons Exposed to Ischemia-like Conditions. Antioxidants (Basel) 2023; 12:antiox12020358. [PMID: 36829918 PMCID: PMC9952397 DOI: 10.3390/antiox12020358] [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: 12/15/2022] [Revised: 01/26/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023] Open
Abstract
Neurodegenerative diseases are characterized by mitochondrial dysfunction leading to abnormal levels of reactive oxygen species (ROS), making the use of ROS-scavenging nanomaterials a promising therapeutic approach. Here, we combined the unique ROS-scavenging properties of cerium-based nanomaterials with the lipid self-assembling nanoparticles (SANP) technology. We optimized the preparation of cerium-doped SANP (Ce-SANP) and characterized the formulations in terms of both physiochemical and biological properties. Ce-SANP exhibited good colloidal properties and were able to mimic the activity of two ROS-scavenging enzymes, namely peroxidase and super oxide dismutase. Under ischemia-like conditions, Ce-SANP could rescue neuronal cells from mitochondrial suffering by reducing ROS production and preventing ATP level reduction. Furthermore, Ce-SANP prevented mitochondrial Ca2+ homeostasis dysfunction, partially restoring mitochondrial Ca2+ handling. Taken together, these results highlight the potential of the anti-oxidant Ce-SANP platform technology to manage ROS levels and mitochondrial function for the treatment of neurodegenerative diseases.
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Paksoy A, Hoppe S, Dörflinger Y, Horstmann H, Sätzler K, Körber C. Effects of the clathrin inhibitor Pitstop-2 on synaptic vesicle recycling at a central synapse in vivo. Front Synaptic Neurosci 2022; 14:1056308. [PMID: 36466146 PMCID: PMC9714552 DOI: 10.3389/fnsyn.2022.1056308] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/03/2022] [Indexed: 01/21/2024] Open
Abstract
Four modes of endocytosis and subsequent synaptic vesicle (SV) recycling have been described at the presynapse to ensure the availability of SVs for synaptic release. However, it is unclear to what extend these modes operate under physiological activity patterns in vivo. The coat protein clathrin can regenerate SVs either directly from the plasma membrane (PM) via clathrin-mediated endocytosis (CME), or indirectly from synaptic endosomes by SV budding. Here, we examined the role of clathrin in SV recycling under physiological conditions by applying the clathrin inhibitor Pitstop-2 to the calyx of Held, a synapse optimized for high frequency synaptic transmission in the auditory brainstem, in vivo. The effects of clathrin-inhibition on SV recycling were investigated by serial sectioning scanning electron microscopy (S3EM) and 3D reconstructions of endocytic structures labeled by the endocytosis marker horseradish peroxidase (HRP). We observed large endosomal compartments as well as HRP-filled, black SVs (bSVs) that have been recently recycled. The application of Pitstop-2 led to reduced bSV but not large endosome density, increased volumes of large endosomes and shifts in the localization of both types of endocytic compartments within the synapse. These changes after perturbation of clathrin function suggest that clathrin plays a role in SV recycling from both, the PM and large endosomes, under physiological activity patterns, in vivo.
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Affiliation(s)
- Alp Paksoy
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Simone Hoppe
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Yvette Dörflinger
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Heinz Horstmann
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Kurt Sätzler
- School of Biomedical Sciences, University of Ulster, Coleraine, United Kingdom
| | - Christoph Körber
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
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Blok LER, Boon M, van Reijmersdal B, Höffler KD, Fenckova M, Schenck A. Genetics, molecular control and clinical relevance of habituation learning. Neurosci Biobehav Rev 2022; 143:104883. [PMID: 36152842 DOI: 10.1016/j.neubiorev.2022.104883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/08/2022] [Accepted: 08/30/2022] [Indexed: 11/29/2022]
Abstract
Habituation is the most fundamental form of learning. As a firewall that protects our brain from sensory overload, it is indispensable for cognitive processes. Studies in humans and animal models provide increasing evidence that habituation is affected in autism and related monogenic neurodevelopmental disorders (NDDs). An integrated application of habituation assessment in NDDs and their animal models has unexploited potential for neuroscience and medical care. With the aim to gain mechanistic insights, we systematically retrieved genes that have been demonstrated in the literature to underlie habituation. We identified 258 evolutionarily conserved genes across species, describe the biological processes they converge on, and highlight regulatory pathways and drugs that may alleviate habituation deficits. We also summarize current habituation paradigms and extract the most decisive arguments that support the crucial role of habituation for cognition in health and disease. We conclude that habituation is a conserved, quantitative, cognition- and disease-relevant process that can connect preclinical and clinical work, and hence is a powerful tool to advance research, diagnostics, and treatment of NDDs.
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Affiliation(s)
- Laura Elisabeth Rosalie Blok
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
| | - Marina Boon
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
| | - Boyd van Reijmersdal
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
| | - Kira Daniela Höffler
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
| | - Michaela Fenckova
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands; Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia in Ceske Budejovice, Branisovska 31, 37005, Ceske Budejovice, Czech Republic.
| | - Annette Schenck
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
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10
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Differential Methylation Profile in Fragile X Syndrome-Prone Offspring Mice after in Utero Exposure to Lactobacillus Reuteri. Genes (Basel) 2022; 13:genes13081300. [PMID: 35893036 PMCID: PMC9331364 DOI: 10.3390/genes13081300] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 07/14/2022] [Accepted: 07/19/2022] [Indexed: 01/13/2023] Open
Abstract
Environmental factors such as diet, gut microbiota, and infections have proven to have a significant role in epigenetic modifications. It is known that epigenetic modifications may cause behavioral and neuronal changes observed in neurodevelopmental disabilities, including fragile X syndrome (FXS) and autism (ASD). Probiotics are live microorganisms that provide health benefits when consumed, and in some cases are shown to decrease the chance of developing neurological disorders. Here, we examined the epigenetic outcomes in offspring mice after feeding of a probiotic organism, Lactobacillus reuteri (L. reuteri), to pregnant mother animals. In this study, we tested a cohort of Western diet-fed descendant mice exhibiting a high frequency of behavioral features and lower FMRP protein expression similar to what is observed in FXS in humans (described in a companion manuscript in this same GENES special topic issue). By investigating 17,735 CpG sites spanning the whole mouse genome, we characterized the epigenetic profile in two cohorts of mice descended from mothers treated and non-treated with L. reuteri to determine the effect of prenatal probiotic exposure on the prevention of FXS-like symptoms. We found several genes involved in different neurological pathways being differentially methylated (p ≤ 0.05) between the cohorts. Among the key functions, synaptogenesis, neurogenesis, synaptic modulation, synaptic transmission, reelin signaling pathway, promotion of specification and maturation of neurons, and long-term potentiation were observed. The results of this study are relevant as they could lead to a better understanding of the pathways involved in these disorders, to novel therapeutics approaches, and to the identification of potential biomarkers for early detection of these conditions.
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Mechanisms of Synaptic Vesicle Exo- and Endocytosis. Biomedicines 2022; 10:biomedicines10071593. [PMID: 35884898 PMCID: PMC9313035 DOI: 10.3390/biomedicines10071593] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 01/05/2023] Open
Abstract
Within 1 millisecond of action potential arrival at presynaptic terminals voltage-gated Ca2+ channels open. The Ca2+ channels are linked to synaptic vesicles which are tethered by active zone proteins. Ca2+ entrance into the active zone triggers: (1) the fusion of the vesicle and exocytosis, (2) the replenishment of the active zone with vesicles for incoming exocytosis, and (3) various types of endocytosis for vesicle reuse, dependent on the pattern of firing. These time-dependent vesicle dynamics are controlled by presynaptic Ca2+ sensor proteins, regulating active zone scaffold proteins, fusion machinery proteins, motor proteins, endocytic proteins, several enzymes, and even Ca2+ channels, following the decay of Ca2+ concentration after the action potential. Here, I summarize the Ca2+-dependent protein controls of synchronous and asynchronous vesicle release, rapid replenishment of the active zone, endocytosis, and short-term plasticity within 100 msec after the action potential. Furthermore, I discuss the contribution of active zone proteins to presynaptic plasticity and to homeostatic readjustment during and after intense activity, in addition to activity-dependent endocytosis.
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12
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López-Hernández T, Takenaka KI, Mori Y, Kongpracha P, Nagamori S, Haucke V, Takamori S. Clathrin-independent endocytic retrieval of SV proteins mediated by the clathrin adaptor AP-2 at mammalian central synapses. eLife 2022; 11:e71198. [PMID: 35014951 PMCID: PMC8752090 DOI: 10.7554/elife.71198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 12/28/2021] [Indexed: 12/25/2022] Open
Abstract
Neurotransmission is based on the exocytic fusion of synaptic vesicles (SVs) followed by endocytic membrane retrieval and the reformation of SVs. Conflicting models have been proposed regarding the mechanisms of SV endocytosis, most notably clathrin/adaptor protein complex 2 (AP-2)-mediated endocytosis and clathrin-independent ultrafast endocytosis. Partitioning between these pathways has been suggested to be controlled by temperature and stimulus paradigm. We report on the comprehensive survey of six major SV proteins to show that SV endocytosis in mouse hippocampal neurons at physiological temperature occurs independent of clathrin while the endocytic retrieval of a subset of SV proteins including the vesicular transporters for glutamate and GABA depend on sorting by the clathrin adaptor AP-2. Our findings highlight a clathrin-independent role of the clathrin adaptor AP-2 in the endocytic retrieval of select SV cargos from the presynaptic cell surface and suggest a revised model for the endocytosis of SV membranes at mammalian central synapses.
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Affiliation(s)
| | - Koh-ichiro Takenaka
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha UniversityKyotoJapan
| | - Yasunori Mori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha UniversityKyotoJapan
| | - Pornparn Kongpracha
- Department of Laboratory Medicine, The Jikei University School of MedicineTokyoJapan
| | - Shushi Nagamori
- Department of Laboratory Medicine, The Jikei University School of MedicineTokyoJapan
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP)BerlinGermany
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha UniversityKyotoJapan
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13
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Mori Y, Takenaka KI, Fukazawa Y, Takamori S. The endosomal Q-SNARE, Syntaxin 7, defines a rapidly replenishing synaptic vesicle recycling pool in hippocampal neurons. Commun Biol 2021; 4:981. [PMID: 34408265 PMCID: PMC8373932 DOI: 10.1038/s42003-021-02512-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 08/02/2021] [Indexed: 12/12/2022] Open
Abstract
Upon the arrival of repetitive stimulation at the presynaptic terminals of neurons, replenishment of readily releasable synaptic vesicles (SVs) with vesicles in the recycling pool is important for sustained neurotransmitter release. Kinetics of replenishment and the available pool size define synaptic performance. However, whether all SVs in the recycling pool are recruited for release with equal probability and speed is unknown. Here, based on comprehensive optical imaging of various presynaptic endosomal SNARE proteins in cultured hippocampal neurons, all of which are implicated in organellar membrane fusion in non-neuronal cells, we show that part of the recycling pool bearing the endosomal Q-SNARE, syntaxin 7 (Stx7), is preferentially mobilized for release during high-frequency repetitive stimulation. Recruitment of the SV pool marked with an Stx7-reporter requires actin polymerization, as well as activation of the Ca2+/calmodulin signaling pathway, reminiscent of rapidly replenishing SVs characterized previously in calyx of Held synapses. Furthermore, disruption of Stx7 function by overexpressing its N-terminal domain selectively abolished this pool. Thus, our data indicate that endosomal membrane fusion involving Stx7 forms rapidly replenishing vesicles essential for synaptic responses to high-frequency repetitive stimulation, and also highlight functional diversities of endosomal SNAREs in generating distinct exocytic vesicles in the presynaptic terminals. Yasunori Mori et al. find that a subset of neurotransmitter-bearing synaptic vesicles are marked for release by the endosomal Q-SNARE protein Stx7. They show that Stx7 function is necessary for the rapid replenishment of synaptic vesicles that is needed to sustain synaptic transmission during high-frequency stimulation.
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Affiliation(s)
- Yasunori Mori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan. .,Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.
| | - Koh-Ichiro Takenaka
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Yugo Fukazawa
- Division of Brain Structure and Function, Research Center for Child Mental Development, Life Science Innovation Center, School of Medical Science, University of Fukui, Fukui, Japan
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan.
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14
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Camblor-Perujo S, Kononenko NL. Brain-specific functions of the endocytic machinery. FEBS J 2021; 289:2219-2246. [PMID: 33896112 DOI: 10.1111/febs.15897] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 03/29/2021] [Indexed: 12/12/2022]
Abstract
Endocytosis is an essential cellular process required for multiple physiological functions, including communication with the extracellular environment, nutrient uptake, and signaling by the cell surface receptors. In a broad sense, endocytosis is accomplished through either constitutive or ligand-induced invagination of the plasma membrane, which results in the formation of the plasma membrane-retrieved endocytic vesicles, which can either be sent for degradation to the lysosomes or recycled back to the PM. This additional function of endocytosis in membrane retrieval has been adopted by excitable cells, such as neurons, for membrane equilibrium maintenance at synapses. The last two decades were especially productive with respect to the identification of brain-specific functions of the endocytic machinery, which additionally include but not limited to regulation of neuronal differentiation and migration, maintenance of neuron morphology and synaptic plasticity, and prevention of neurotoxic aggregates spreading. In this review, we highlight the current knowledge of brain-specific functions of endocytic machinery with a specific focus on three brain cell types, neuronal progenitor cells, neurons, and glial cells.
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Affiliation(s)
| | - Natalia L Kononenko
- CECAD Cluster of Excellence, University of Cologne, Germany.,Center for Physiology & Pathophysiology, Medical Faculty, University of Cologne, Germany
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15
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Ivanova D, Dobson KL, Gajbhiye A, Davenport EC, Hacker D, Ultanir SK, Trost M, Cousin MA. Control of synaptic vesicle release probability via VAMP4 targeting to endolysosomes. SCIENCE ADVANCES 2021; 7:7/18/eabf3873. [PMID: 33931449 PMCID: PMC8087399 DOI: 10.1126/sciadv.abf3873] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 03/11/2021] [Indexed: 05/03/2023]
Abstract
Synaptic vesicle (SV) release probability (Pr), determines the steady state and plastic control of neurotransmitter release. However, how diversity in SV composition arises and regulates the Pr of individual SVs is not understood. We found that modulation of the copy number of the noncanonical vesicular SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor), vesicle-associated membrane protein 4 (VAMP4), on SVs is key for regulating Pr. Mechanistically, this is underpinned by its reduced ability to form an efficient SNARE complex with canonical plasma membrane SNAREs. VAMP4 has unusually high synaptic turnover and is selectively sorted to endolysosomes during activity-dependent bulk endocytosis. Disruption of endolysosomal trafficking and function markedly increased the abundance of VAMP4 in the SV pool and inhibited SV fusion. Together, our results unravel a new mechanism for generating SV heterogeneity and control of Pr through coupling of SV recycling to a major clearing system that regulates protein homeostasis.
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Affiliation(s)
- Daniela Ivanova
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland.
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
| | - Katharine L Dobson
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
| | - Akshada Gajbhiye
- Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle upon Tyne NE2 4HH, UK
| | - Elizabeth C Davenport
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
| | - Daniela Hacker
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
| | - Sila K Ultanir
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Matthias Trost
- Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle upon Tyne NE2 4HH, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland.
- Muir Maxwell Epilepsy Centre, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
- Simons Initiative for the Developing Brain, Hugh Robson Building, George Square, University of Edinburgh, Edinburgh EH8 9XD, Scotland
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16
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Harper CB, Smillie KJ. Current molecular approaches to investigate pre-synaptic dysfunction. J Neurochem 2021; 157:107-129. [PMID: 33544872 DOI: 10.1111/jnc.15316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022]
Abstract
Over the course of the last few decades it has become clear that many neurodevelopmental and neurodegenerative disorders have a synaptic defect, which contributes to pathogenicity. A rise in new techniques, and in particular '-omics'-based methods providing large datasets, has led to an increase in potential proteins and pathways implicated in synaptic function and related disorders. Additionally, advancements in imaging techniques have led to the recent discovery of alternative modes of synaptic vesicle recycling. This has resulted in a lack of clarity over the precise role of different pathways in maintaining synaptic function and whether these new pathways are dysfunctional in neurodevelopmental and neurodegenerative disorders. A greater understanding of the molecular detail of pre-synaptic function in health and disease is key to targeting new proteins and pathways for novel treatments and the variety of new techniques currently available provides an ideal opportunity to investigate these functions. This review focuses on techniques to interrogate pre-synaptic function, concentrating mainly on synaptic vesicle recycling. It further examines techniques to determine the underlying molecular mechanism of pre-synaptic dysfunction and discusses methods to identify molecular targets, along with protein-protein interactions and cellular localization. In combination, these techniques will provide an expanding and more complete picture of pre-synaptic function. With the application of recent technological advances, we are able to resolve events with higher spatial and temporal resolution, leading research towards a greater understanding of dysfunction at the presynapse and the role it plays in pathogenicity.
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Affiliation(s)
- Callista B Harper
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
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17
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Ivanova D, Imig C, Camacho M, Reinhold A, Guhathakurta D, Montenegro-Venegas C, Cousin MA, Gundelfinger ED, Rosenmund C, Cooper B, Fejtova A. CtBP1-Mediated Membrane Fission Contributes to Effective Recycling of Synaptic Vesicles. Cell Rep 2021; 30:2444-2459.e7. [PMID: 32075774 PMCID: PMC7034063 DOI: 10.1016/j.celrep.2020.01.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 12/12/2019] [Accepted: 01/22/2020] [Indexed: 01/08/2023] Open
Abstract
Compensatory endocytosis of released synaptic vesicles (SVs) relies on coordinated signaling at the lipid-protein interface. Here, we address the synaptic function of C-terminal binding protein 1 (CtBP1), a ubiquitous regulator of gene expression and membrane trafficking in cultured hippocampal neurons. In the absence of CtBP1, synapses form in greater density and show changes in SV distribution and size. The increased basal neurotransmission and enhanced synaptic depression could be attributed to a higher vesicular release probability and a smaller fraction of release-competent SVs, respectively. Rescue experiments with specifically targeted constructs indicate that, while synaptogenesis and release probability are controlled by nuclear CtBP1, the efficient recycling of SVs relies on its synaptic expression. The ability of presynaptic CtBP1 to facilitate compensatory endocytosis depends on its membrane-fission activity and the activation of the lipid-metabolizing enzyme PLD1. Thus, CtBP1 regulates SV recycling by promoting a permissive lipid environment for compensatory endocytosis.
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Affiliation(s)
- Daniela Ivanova
- RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany; Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Cordelia Imig
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, German
| | - Marcial Camacho
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Annika Reinhold
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Debarpan Guhathakurta
- Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | | | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson Building, George Square, University of Edinburgh, EH9 9XD Edinburgh, UK
| | - Eckart D Gundelfinger
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Center for Behavioral Brain Science and Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Christian Rosenmund
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Benjamin Cooper
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, German
| | - Anna Fejtova
- RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany; Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany; Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
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18
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Distinct synaptic vesicle recycling in inhibitory nerve terminals is coordinated by SV2A. Prog Neurobiol 2020; 194:101879. [DOI: 10.1016/j.pneurobio.2020.101879] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 05/05/2020] [Accepted: 06/26/2020] [Indexed: 01/08/2023]
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19
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Overhoff M, De Bruyckere E, Kononenko NL. Mechanisms of neuronal survival safeguarded by endocytosis and autophagy. J Neurochem 2020; 157:263-296. [PMID: 32964462 DOI: 10.1111/jnc.15194] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/21/2020] [Accepted: 09/08/2020] [Indexed: 12/11/2022]
Abstract
Multiple aspects of neuronal physiology crucially depend on two cellular pathways, autophagy and endocytosis. During endocytosis, extracellular components either unbound or recognized by membrane-localized receptors (termed "cargo") become internalized into plasma membrane-derived vesicles. These can serve to either recycle the material back to the plasma membrane or send it for degradation to lysosomes. Autophagy also uses lysosomes as a terminal degradation point, although instead of degrading the plasma membrane-derived cargo, autophagy eliminates detrimental cytosolic material and intracellular organelles, which are transported to lysosomes by means of double-membrane vesicles, referred to as autophagosomes. Neurons, like all non-neuronal cells, capitalize on autophagy and endocytosis to communicate with the environment and maintain protein and organelle homeostasis. Additionally, the highly polarized, post-mitotic nature of neurons made them adopt these two pathways for cell-specific functions. These include the maintenance of the synaptic vesicle pool in the pre-synaptic terminal and the long-distance transport of signaling molecules. Originally discovered independently from each other, it is now clear that autophagy and endocytosis are closely interconnected and share several common participating molecules. Considering the crucial role of autophagy and endocytosis in cell type-specific functions in neurons, it is not surprising that defects in both pathways have been linked to the pathology of numerous neurodegenerative diseases. In this review, we highlight the recent knowledge of the role of endocytosis and autophagy in neurons with a special focus on synaptic physiology and discuss how impairments in genes coding for autophagy and endocytosis proteins can cause neurodegeneration.
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Affiliation(s)
- Melina Overhoff
- CECAD Cluster of Excellence, Institute for Genetics, University of Cologne, Cologne, Germany
| | - Elodie De Bruyckere
- CECAD Cluster of Excellence, Institute for Genetics, University of Cologne, Cologne, Germany
| | - Natalia L Kononenko
- CECAD Cluster of Excellence, Institute for Genetics, University of Cologne, Cologne, Germany
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20
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Yong XLH, Cousin MA, Anggono V. PICK1 Controls Activity-Dependent Synaptic Vesicle Cargo Retrieval. Cell Rep 2020; 33:108312. [PMID: 33113376 DOI: 10.1016/j.celrep.2020.108312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 09/03/2020] [Accepted: 10/05/2020] [Indexed: 12/23/2022] Open
Abstract
Efficient retrieval of synaptic vesicles (SVs) is crucial to sustain synaptic transmission. Protein interacting with C-kinase 1 (PICK1) is a unique PDZ (postsynaptic density-95/disc-large/zona-occluden-1)- and BAR (Bin-Amphiphysin-Rvs )-domain-containing protein that regulates the trafficking of postsynaptic glutamate receptors. It is also expressed in presynaptic terminals and is associated with the SVs; however, its role in regulating SV recycling remains unknown. Here, we show that PICK1 loss of function selectively slows the kinetics of SV endocytosis in primary hippocampal neurons during high-frequency stimulation. PICK1 knockdown also causes surface stranding and mislocalization of major SV proteins, synaptophysin and vGlut1, along the axon. A functional PDZ domain of PICK1 and its interaction with the core endocytic adaptor protein (AP)-2 are required for the proper targeting and clustering of synaptophysin. Furthermore, PICK1 and its interaction with AP-2 are required for efficient SV endocytosis and sustained glutamate release. Our findings, therefore, identify PICK1 as a key regulator of presynaptic vesicle recycling in central synapses.
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Affiliation(s)
- Xuan Ling Hilary Yong
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, Scotland, UK; Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh EH8 9XD, Scotland, UK; Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, Scotland, UK
| | - Victor Anggono
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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21
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The Synaptic Vesicle Cycle Revisited: New Insights into the Modes and Mechanisms. J Neurosci 2020; 39:8209-8216. [PMID: 31619489 DOI: 10.1523/jneurosci.1158-19.2019] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 07/31/2019] [Accepted: 08/03/2019] [Indexed: 02/01/2023] Open
Abstract
Neurotransmission is sustained by endocytosis and refilling of synaptic vesicles (SVs) locally within the presynapse. Until recently, a consensus formed that after exocytosis, SVs are recovered by either fusion pore closure (kiss-and-run) or clathrin-mediated endocytosis directly from the plasma membrane. However, recent data have revealed that SV formation is more complex than previously envisaged. For example, two additional recycling pathways have been discovered, ultrafast endocytosis and activity-dependent bulk endocytosis, in which SVs are regenerated from the internalized membrane and synaptic endosomes. Furthermore, these diverse modes of endocytosis appear to influence both the molecular composition and subsequent physiological role of individual SVs. In addition, previously unknown complexity in SV refilling and reclustering has been revealed. This review presents a modern view of the SV life cycle and discusses how neuronal subtype, physiological temperature, and individual activity patterns can recruit different endocytic modes to generate new SVs and sculpt subsequent presynaptic performance.
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22
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Rosselli-Murai LK, Joseph JG, Lopes-Cendes I, Liu AP, Murai MJ. The Machado-Joseph disease-associated form of ataxin-3 impacts dynamics of clathrin-coated pits. Cell Biol Int 2020; 44:1252-1259. [PMID: 31970864 DOI: 10.1002/cbin.11312] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 01/22/2020] [Indexed: 12/14/2022]
Abstract
Expansion above a certain threshold in the polyglutamine (polyQ) tract of ataxin-3 is the main cause of neurodegeneration in Machado-Joseph disease. Ataxin-3 contains an N-terminal catalytic domain, called Josephin domain, and a highly aggregation-prone C-terminal domain containing the polyQ tract. Recent work has shown that protein aggregation inhibits clathrin-mediated endocytosis (CME). However, the effects of polyQ expansion in ataxin-3 on CME have not been investigated. We hypothesize that the expansion of the polyQ tract in ataxin-3 could impact CME. Here, we report that both the wild-type and the expanded ataxin-3 reduce transferrin internalization and expanded ataxin-3 impacts dynamics of clathrin-coated pits (CCPs) by reducing CCP nucleation and increasing short-lived abortive CCPs. Since endocytosis plays a central role in regulating receptor uptake and cargo release, our work highlights a potential mechanism linking protein aggregation to cellular dysregulation.
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Affiliation(s)
- Luciana K Rosselli-Murai
- Department of Pharmacology, University of Michigan Medical School, 2301 MSRB III, 1150 W. Medical Center Dr., Ann Arbor, Michigan, 48109, USA.,Department of Mechanical Engineering, University of Michigan, 2674 GGB, 2350 Hayward, Ann Arbor, Michigan, 48109, USA
| | - Jophin G Joseph
- Department of Mechanical Engineering, University of Michigan, 2674 GGB, 2350 Hayward, Ann Arbor, Michigan, 48109, USA
| | - Iscia Lopes-Cendes
- Department of Medical Genetics, School of Medical Sciences, University of Campinas, R. Tessália Vieira de Camargo, 126, Campinas, São Paulo, 13083-970, Brazil.,The Brazilian Institute of Neuroscience and Neurotechnology, R. Vital Brasil, 251, Campinas, São Paulo, 13083-888, Brazil
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, 2674 GGB, 2350 Hayward, Ann Arbor, Michigan, 48109, USA
| | - Marcelo J Murai
- Department of Pharmacology, University of Michigan Medical School, 2301 MSRB III, 1150 W. Medical Center Dr., Ann Arbor, Michigan, 48109, USA.,Department of Medical Genetics, School of Medical Sciences, University of Campinas, R. Tessália Vieira de Camargo, 126, Campinas, São Paulo, 13083-970, Brazil
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23
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Yap CC, Digilio L, Kruczek K, Roszkowska M, Fu XQ, Liu JS, Winckler B. A dominant dendrite phenotype caused by the disease-associated G253D mutation in doublecortin (DCX) is not due to its endocytosis defect. J Biol Chem 2018; 293:18890-18902. [PMID: 30291144 DOI: 10.1074/jbc.ra118.004462] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 09/29/2018] [Indexed: 01/14/2023] Open
Abstract
Doublecortin (DCX) is a protein needed for cortical development, and DCX mutations cause cortical malformations in humans. The microtubule-binding activity of DCX is well-described and is important for its function, such as supporting neuronal migration and dendrite growth during development. Previous work showed that microtubule binding is not sufficient for DCX-mediated promotion of dendrite growth and that domains in DCX's C terminus are also required. The more C-terminal regions of DCX bind several other proteins, including the adhesion receptor neurofascin and clathrin adaptors. We recently identified a role for DCX in endocytosis of neurofascin. The disease-associated DCX-G253D mutant protein is known to be deficient in binding neurofascin, and we now asked if disruption of neurofascin endocytosis underlies the DCX-G253D-associated pathology. We first demonstrated that DCX functions in endocytosis as a complex with both the clathrin adaptor AP-2 and neurofascin: disrupting either clathrin adaptor binding (DCX-ALPA) or neurofascin binding (DCX-G253D) decreased neurofascin endocytosis in primary neurons. We then investigated a known function for DCX, namely, increasing dendrite growth in cultured neurons. Surprisingly, we found that the DCX-ALPA and DCX-G253D mutants yield distinct dendrite phenotypes. Unlike DCX-ALPA, DCX-G253D caused a dominant-negative dendrite growth phenotype. The endocytosis defect of DCX-G253D thus was separable from its detrimental effects on dendrite growth. We recently identified Dcx-R59H as a dominant allele and can now classify Dcx-G253D as a second Dcx allele that acts dominantly to cause pathology, but does so via a different mechanism.
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Affiliation(s)
- Chan Choo Yap
- From the Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908
| | - Laura Digilio
- From the Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908
| | | | - Matylda Roszkowska
- the Faculty of Biology and Earth Sciences, Jagiellonian University, 31-007 Cracow, Poland, and
| | - Xiao-Qin Fu
- the Department of Neurology, Brown University, Providence, Rhode Island 02912
| | - Judy S Liu
- the Department of Neurology, Brown University, Providence, Rhode Island 02912
| | - Bettina Winckler
- From the Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908,
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24
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Postnatal Restriction of Activity-Induced Ca 2+ Responses to Schwann Cells at the Neuromuscular Junction Are Caused by the Proximo-Distal Loss of Axonal Synaptic Vesicles during Development. J Neurosci 2018; 38:8650-8665. [PMID: 30143570 DOI: 10.1523/jneurosci.0956-18.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 08/08/2018] [Accepted: 08/16/2018] [Indexed: 12/27/2022] Open
Abstract
Terminal or perisynaptic Schwann cells (TPSCs) are nonmyelinating, perisynaptic glial cells at the neuromuscular junction (NMJ) that respond to neural activity by increasing intracellular calcium (Ca2+) and regulate synaptic function. The onset of activity-induced TPSC Ca2+ responses, as well as whether axonal Schwann cells (ASCs) along the nerve respond to nerve stimulation during development, is unknown. Here, we show that phrenic nerve stimulation in developing male and female mice elicited Ca2+ responses in both ASCs and TPSCs at embryonic day 14. ASC responses were lost in a proximo-distal gradient over time, but could continue to be elicited by bath application of neurotransmitter, suggesting that a loss of release rather than a change in ASC competence accounted for this response gradient. Similar to those of early postnatal TPSCs, developing ASC/TPSC responses were mediated by purinergic P2Y1 receptors. The loss of ASC Ca2+ responses was correlated to the proximo-distal disappearance of synaptophysin immunoreactivity and synaptic vesicles in phrenic axons. Accordingly, developing ASC Ca2+ responses were blocked by botulinum toxin. Interestingly, the loss of ASC Ca2+ responses was also correlated to the proximo-distal development of myelination. Finally, compared with postnatal TPSCs, neonatal TPSCs and ASCs displayed Ca2+ signals in response to lower frequencies and shorter durations of nerve stimulation. Together, these results with GCaMP3-expressing Schwann cells provide ex vivo evidence that both axons and presynaptic terminals initially exhibit activity-induced vesicular release of neurotransmitter, but that the subsequent loss of axonal synaptic vesicles accounts for the postnatal restriction of vesicular release to the NMJ.SIGNIFICANCE STATEMENT Neural activity regulates multiple aspects of development, including myelination. Whether the excitation of developing neurons in vivo results in the release of neurotransmitter from both axons and presynaptic terminals is unclear. Here, using mice expressing the genetically encoded calcium indicator GCaMP3 in Schwann cells, we show that both terminal/perisynaptic Schwann cells at the diaphragm neuromuscular junction and axonal Schwann cells along the phrenic nerve exhibit activity-induced calcium responses early in development, mediated by the vesicular release of ATP from the axons of motor neurons acting on P2Y1 receptors. These ex vivo findings corroborate classic in vitro studies demonstrating transmitter release by developing axons, and thus represent a tool to study the mechanisms and significance of this process during embryonic development.
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Piccini A, Castroflorio E, Valente P, Guarnieri FC, Aprile D, Michetti C, Bramini M, Giansante G, Pinto B, Savardi A, Cesca F, Bachi A, Cattaneo A, Wren JD, Fassio A, Valtorta F, Benfenati F, Giovedì S. APache Is an AP2-Interacting Protein Involved in Synaptic Vesicle Trafficking and Neuronal Development. Cell Rep 2018; 21:3596-3611. [PMID: 29262337 DOI: 10.1016/j.celrep.2017.11.073] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 10/23/2017] [Accepted: 11/20/2017] [Indexed: 11/25/2022] Open
Abstract
Synaptic transmission is critically dependent on synaptic vesicle (SV) recycling. Although the precise mechanisms of SV retrieval are still debated, it is widely accepted that a fundamental role is played by clathrin-mediated endocytosis, a form of endocytosis that capitalizes on the clathrin/adaptor protein complex 2 (AP2) coat and several accessory factors. Here, we show that the previously uncharacterized protein KIAA1107, predicted by bioinformatics analysis to be involved in the SV cycle, is an AP2-interacting clathrin-endocytosis protein (APache). We found that APache is highly enriched in the CNS and is associated with clathrin-coated vesicles via interaction with AP2. APache-silenced neurons exhibit a severe impairment of maturation at early developmental stages, reduced SV density, enlarged endosome-like structures, and defects in synaptic transmission, consistent with an impaired clathrin/AP2-mediated SV recycling. Our data implicate APache as an actor in the complex regulation of SV trafficking, neuronal development, and synaptic plasticity.
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Affiliation(s)
- Alessandra Piccini
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy
| | - Enrico Castroflorio
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Pierluigi Valente
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy
| | - Fabrizia C Guarnieri
- San Raffaele Scientific Institute and Vita Salute University, 20132 Milano, Italy
| | - Davide Aprile
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy
| | - Caterina Michetti
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Mattia Bramini
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Giorgia Giansante
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy
| | - Bruno Pinto
- Local Micro-environment and Brain Development Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Bio@SNS, Scuola Normale Superiore, 56126 Pisa, Italy
| | - Annalisa Savardi
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy; Local Micro-environment and Brain Development Laboratory, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Fabrizia Cesca
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Angela Bachi
- IFOM, FIRC Institute of Molecular Oncology, 20132 Milano, Italy
| | - Angela Cattaneo
- IFOM, FIRC Institute of Molecular Oncology, 20132 Milano, Italy
| | - Jonathan D Wren
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104-5005, USA
| | - Anna Fassio
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy; Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Flavia Valtorta
- San Raffaele Scientific Institute and Vita Salute University, 20132 Milano, Italy
| | - Fabio Benfenati
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy; Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy.
| | - Silvia Giovedì
- Department of Experimental Medicine, University of Genova, 16132 Genova, Italy.
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Gan Q, Watanabe S. Synaptic Vesicle Endocytosis in Different Model Systems. Front Cell Neurosci 2018; 12:171. [PMID: 30002619 PMCID: PMC6031744 DOI: 10.3389/fncel.2018.00171] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 06/01/2018] [Indexed: 11/13/2022] Open
Abstract
Neurotransmission in complex animals depends on a choir of functionally distinct synapses releasing neurotransmitters in a highly coordinated manner. During synaptic signaling, vesicles fuse with the plasma membrane to release their contents. The rate of vesicle fusion is high and can exceed the rate at which synaptic vesicles can be re-supplied by distant sources. Thus, local compensatory endocytosis is needed to replenish the synaptic vesicle pools. Over the last four decades, various experimental methods and model systems have been used to study the cellular and molecular mechanisms underlying synaptic vesicle cycle. Clathrin-mediated endocytosis is thought to be the predominant mechanism for synaptic vesicle recycling. However, recent studies suggest significant contribution from other modes of endocytosis, including fast compensatory endocytosis, activity-dependent bulk endocytosis, ultrafast endocytosis, as well as kiss-and-run. Currently, it is not clear whether a universal model of vesicle recycling exist for all types of synapses. It is possible that each synapse type employs a particular mode of endocytosis. Alternatively, multiple modes of endocytosis operate at the same synapse, and the synapse toggles between different modes depending on its activity level. Here we compile review and research articles based on well-characterized model systems: frog neuromuscular junctions, C. elegans neuromuscular junctions, Drosophila neuromuscular junctions, lamprey reticulospinal giant axons, goldfish retinal ribbon synapses, the calyx of Held, and rodent hippocampal synapses. We will compare these systems in terms of their known modes and kinetics of synaptic vesicle endocytosis, as well as the underlying molecular machineries. We will also provide the future development of this field.
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Affiliation(s)
- Quan Gan
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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Guardia CM, De Pace R, Mattera R, Bonifacino JS. Neuronal functions of adaptor complexes involved in protein sorting. Curr Opin Neurobiol 2018; 51:103-110. [PMID: 29558740 DOI: 10.1016/j.conb.2018.02.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 02/16/2018] [Accepted: 02/27/2018] [Indexed: 11/30/2022]
Abstract
Selective transport of transmembrane proteins to different intracellular compartments often involves the recognition of sorting signals in the cytosolic domains of the proteins by components of membrane coats. Some of these coats have as their key components a family of heterotetrameric adaptor protein (AP) complexes named AP-1 through AP-5. AP complexes play important roles in all cells, but their functions are most critical in neurons because of the extreme compartmental complexity of these cells. Accordingly, various diseases caused by mutations in AP subunit genes exhibit a range of neurological abnormalities as their most salient features. In this article, we discuss the properties of the different AP complexes, with a focus on their roles in neuronal physiology and pathology.
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Affiliation(s)
- Carlos M Guardia
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Raffaella De Pace
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rafael Mattera
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Juan S Bonifacino
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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Milosevic I. Revisiting the Role of Clathrin-Mediated Endoytosis in Synaptic Vesicle Recycling. Front Cell Neurosci 2018; 12:27. [PMID: 29467622 PMCID: PMC5807904 DOI: 10.3389/fncel.2018.00027] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 01/17/2018] [Indexed: 12/11/2022] Open
Abstract
Without robust mechanisms to efficiently form new synaptic vesicles (SVs), the tens to hundreds of SVs typically present at the neuronal synapse would be rapidly used up, even at modest levels of neuronal activity. SV recycling is thus critical for synaptic physiology and proper function of sensory and nervous systems. Yet, more than four decades after it was originally proposed that the SVs are formed and recycled locally at the presynaptic terminals, the mechanisms of endocytic processes at the synapse are heavily debated. Clathrin-mediated endocytosis, a type of endocytosis that capitalizes on the clathrin coat, a number of adaptor and accessory proteins, and the GTPase dynamin, is well understood, while the contributions of clathrin-independent fast endocytosis, kiss-and-run, bulk endocytosis and ultrafast endocytosis are still being evaluated. This review article revisits and summarizes the current knowledge on the SV reformation with a focus on clathrin-mediated endocytosis, and it discusses the modes of SV formation from endosome-like structures at the synapse. Given the importance of this topic, future advances in this active field are expected to contribute to better comprehension of neurotransmission, and to have general implications for neuroscience and medicine.
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Affiliation(s)
- Ira Milosevic
- Synaptic Vesicle Dynamics Group, European Neuroscience Institute (ENI), University Medical Center Göttingen (UMG), Göttingen, Germany
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DJ-1 deficiency impairs synaptic vesicle endocytosis and reavailability at nerve terminals. Proc Natl Acad Sci U S A 2018; 115:1629-1634. [PMID: 29386384 DOI: 10.1073/pnas.1708754115] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutations in DJ-1 (PARK7) are a known cause of early-onset autosomal recessive Parkinson's disease (PD). Accumulating evidence indicates that abnormalities of synaptic vesicle trafficking underlie the pathophysiological mechanism of PD. In the present study, we explored whether DJ-1 is involved in CNS synaptic function. DJ-1 deficiency impaired synaptic vesicle endocytosis and reavailability without inducing structural alterations in synapses. Familial mutants of DJ-1 (M26I, E64D, and L166P) were unable to rescue defective endocytosis of synaptic vesicles, whereas WT DJ-1 expression completely restored endocytic function in DJ-1 KO neurons. The defective synaptic endocytosis shown in DJ-1 KO neurons may be attributable to alterations in membrane cholesterol level. Thus, DJ-1 appears essential for synaptic vesicle endocytosis and reavailability, and impairment of this function by familial mutants of DJ-1 may be related to the pathogenesis of PD.
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Mori Y, Takamori S. Molecular Signatures Underlying Synaptic Vesicle Cargo Retrieval. Front Cell Neurosci 2018; 11:422. [PMID: 29379416 PMCID: PMC5770824 DOI: 10.3389/fncel.2017.00422] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 12/15/2017] [Indexed: 12/31/2022] Open
Abstract
Efficient retrieval of the synaptic vesicle (SV) membrane from the presynaptic plasma membrane, a process called endocytosis, is crucial for the fidelity of neurotransmission, particularly during sustained neural activity. Although multiple modes of endocytosis have been identified, it is clear that the efficient retrieval of the major SV cargos into newly formed SVs during any of these modes is fundamental for synaptic transmission. It is currently believed that SVs are eventually reformed via a clathrin-dependent pathway. Various adaptor proteins recognize SV cargos and link them to clathrin, ensuring the efficient retrieval of the cargos into newly formed SVs. Here, we summarize our current knowledge of the molecular signatures within individual SV cargos that underlie efficient retrieval into SV membranes, as well as discuss possible contributions of the mechanisms under physiological conditions.
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Affiliation(s)
- Yasunori Mori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
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31
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Cousin MA, Gordon SL, Smillie KJ. Using FM Dyes to Monitor Clathrin-Mediated Endocytosis in Primary Neuronal Culture. Methods Mol Biol 2018; 1847:239-249. [PMID: 30129022 DOI: 10.1007/978-1-4939-8719-1_18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This protocol utilizes lipophilic FM dyes to monitor membrane recycling in real time. FM dyes are virtually nonfluorescent in solution but when membrane bound are intensely fluorescent, combined with the flexibility of different emission wavelengths make these dyes an excellent choice for investigating clathrin-mediated endocytosis, among other membrane trafficking and recycling pathways.
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Affiliation(s)
- Michael A Cousin
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Sarah L Gordon
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK.
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Li H, Santos MS, Park CK, Dobry Y, Voglmaier SM. VGLUT2 Trafficking Is Differentially Regulated by Adaptor Proteins AP-1 and AP-3. Front Cell Neurosci 2017; 11:324. [PMID: 29123471 PMCID: PMC5662623 DOI: 10.3389/fncel.2017.00324] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Accepted: 09/28/2017] [Indexed: 01/25/2023] Open
Abstract
Release of the major excitatory neurotransmitter glutamate by synaptic vesicle exocytosis depends on glutamate loading into synaptic vesicles by vesicular glutamate transporters (VGLUTs). The two principal isoforms, VGLUT1 and 2, exhibit a complementary pattern of expression in adult brain that broadly distinguishes cortical (VGLUT1) and subcortical (VGLUT2) systems, and correlates with distinct physiological properties in synapses expressing these isoforms. Differential trafficking of VGLUT1 and 2 has been suggested to underlie their functional diversity. Increasing evidence suggests individual synaptic vesicle proteins use specific sorting signals to engage specialized biochemical mechanisms to regulate their recycling. We observed that VGLUT2 recycles differently in response to high frequency stimulation than VGLUT1. Here we further explore the trafficking of VGLUT2 using a pHluorin-based reporter, VGLUT2-pH. VGLUT2-pH exhibits slower rates of both exocytosis and endocytosis than VGLUT1-pH. VGLUT2-pH recycling is slower than VGLUT1-pH in both hippocampal neurons, which endogenously express mostly VGLUT1, and thalamic neurons, which endogenously express mostly VGLUT2, indicating that protein identity, not synaptic vesicle membrane or neuronal cell type, controls sorting. We characterize sorting signals in the C-terminal dileucine-like motif, which plays a crucial role in VGLUT2 trafficking. Disruption of this motif abolishes synaptic targeting of VGLUT2 and essentially eliminates endocytosis of the transporter. Mutational and biochemical analysis demonstrates that clathrin adaptor proteins (APs) interact with VGLUT2 at the dileucine-like motif. VGLUT2 interacts with AP-2, a well-studied adaptor protein for clathrin mediated endocytosis. In addition, VGLUT2 also interacts with the alternate adaptors, AP-1 and AP-3. VGLUT2 relies on distinct recycling mechanisms from VGLUT1. Abrogation of these differences by pharmacological and molecular inhibition reveals that these mechanisms are dependent on the adaptor proteins AP-1 and AP-3. Further, shRNA-mediated knockdown reveals differential roles for AP-1 and AP-3 in VGLUT2 recycling.
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Affiliation(s)
- Haiyan Li
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
| | - Magda S Santos
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
| | - Chihyung K Park
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
| | - Yuriy Dobry
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
| | - Susan M Voglmaier
- Department of Psychiatry, School of Medicine, Weill Institute for Neurosciences, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA, United States
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Parkinson Sac Domain Mutation in Synaptojanin 1 Impairs Clathrin Uncoating at Synapses and Triggers Dystrophic Changes in Dopaminergic Axons. Neuron 2017; 93:882-896.e5. [PMID: 28231468 DOI: 10.1016/j.neuron.2017.01.019] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 11/22/2016] [Accepted: 01/20/2017] [Indexed: 01/10/2023]
Abstract
Synaptojanin 1 (SJ1) is a major presynaptic phosphatase that couples synaptic vesicle endocytosis to the dephosphorylation of PI(4,5)P2, a reaction needed for the shedding of endocytic factors from their membranes. While the role of SJ1's 5-phosphatase module in this process is well recognized, the contribution of its Sac phosphatase domain, whose preferred substrate is PI4P, remains unclear. Recently a homozygous mutation in its Sac domain was identified in early-onset parkinsonism patients. We show that mice carrying this mutation developed neurological manifestations similar to those of human patients. Synapses of these mice displayed endocytic defects and a striking accumulation of clathrin-coated intermediates, strongly implicating Sac domain's activity in endocytic protein dynamics. Mutant brains had elevated auxilin (PARK19) and parkin (PARK2) levels. Moreover, dystrophic axonal terminal changes were selectively observed in dopaminergic axons in the dorsal striatum. These results strengthen evidence for a link between synaptic endocytic dysfunction and Parkinson's disease.
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Cousin MA. Integration of Synaptic Vesicle Cargo Retrieval with Endocytosis at Central Nerve Terminals. Front Cell Neurosci 2017; 11:234. [PMID: 28824381 PMCID: PMC5541026 DOI: 10.3389/fncel.2017.00234] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 07/25/2017] [Indexed: 12/12/2022] Open
Abstract
Central nerve terminals contain a limited number of synaptic vesicles (SVs) which mediate the essential process of neurotransmitter release during their activity-dependent fusion. The rapid and accurate formation of new SVs with the appropriate cargo is essential to maintain neurotransmission in mammalian brain. Generating SVs containing the correct SV cargo with the appropriate stoichiometry is a significant challenge, especially when multiple modes of endocytosis exist in central nerve terminals, which occur at different locations within the nerve terminals. These endocytosis modes include ultrafast endocytosis, clathrin-mediated endocytosis (CME) and activity-dependent bulk endocytosis (ADBE) which are triggered by specific patterns of neuronal activity. This review article will assess the evidence for the role of classical adaptor protein complexes in SV retrieval, discuss the role of monomeric adaptors and how interactions between specific SV cargoes can facilitate retrieval. In addition it will consider the evidence for preassembled plasma membrane cargo complexes and their role in facilitating these endocytosis modes. Finally it will present a unifying model for cargo retrieval at the presynapse, which integrates endocytosis modes in time and space.
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Affiliation(s)
- Michael A Cousin
- Centre for Integrative Physiology, University of EdinburghEdinburgh, United Kingdom
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35
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Inhibition of Drp1 Ameliorates Synaptic Depression, Aβ Deposition, and Cognitive Impairment in an Alzheimer's Disease Model. J Neurosci 2017; 37:5099-5110. [PMID: 28432138 DOI: 10.1523/jneurosci.2385-16.2017] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 03/30/2017] [Accepted: 04/04/2017] [Indexed: 01/09/2023] Open
Abstract
Excessive mitochondrial fission is a prominent early event and contributes to mitochondrial dysfunction, synaptic failure, and neuronal cell death in the progression of Alzheimer's disease (AD). However, it remains to be determined whether inhibition of excessive mitochondrial fission is beneficial in mammal models of AD. To determine whether dynamin-related protein 1 (Drp1), a key regulator of mitochondrial fragmentation, can be a disease-modifying therapeutic target for AD, we examined the effects of Drp1 inhibitor on mitochondrial and synaptic dysfunctions induced by oligomeric amyloid-β (Aβ) in neurons and neuropathology and cognitive functions in Aβ precursor protein/presenilin 1 double-transgenic AD mice. Inhibition of Drp1 alleviates mitochondrial fragmentation, loss of mitochondrial membrane potential, reactive oxygen species production, ATP reduction, and synaptic depression in Aβ-treated neurons. Furthermore, Drp1 inhibition significantly improves learning and memory and prevents mitochondrial fragmentation, lipid peroxidation, BACE1 expression, and Aβ deposition in the brain in the AD model. These results provide evidence that Drp1 plays an important role in Aβ-mediated and AD-related neuropathology and in cognitive decline in an AD animal model. Therefore, inhibiting excessive Drp1-mediated mitochondrial fission may be an efficient therapeutic avenue for AD.SIGNIFICANCE STATEMENT Mitochondrial fission relies on the evolutionary conserved dynamin-related protein 1 (Drp1). Drp1 activity and mitochondria fragmentation are significantly elevated in the brains of sporadic Alzheimer's disease (AD) cases. In the present study, we first demonstrated that the inhibition of Drp1 restored amyloid-β (Aβ)-mediated mitochondrial dysfunctions and synaptic depression in neurons and significantly reduced lipid peroxidation, BACE1 expression, and Aβ deposition in the brain of AD mice. As a result, memory deficits in AD mice were rescued by Drp1 inhibition. These results suggest that neuropathology and combined cognitive decline can be attributed to hyperactivation of Drp1 in the pathogenesis of AD. Therefore, inhibitors of excessive mitochondrial fission, such as Drp1 inhibitors, may be a new strategy for AD.
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Rampérez A, Sánchez-Prieto J, Torres M. Brefeldin A sensitive mechanisms contribute to endocytotic membrane retrieval and vesicle recycling in cerebellar granule cells. J Neurochem 2017; 141:662-675. [PMID: 28295320 DOI: 10.1111/jnc.14017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 02/22/2017] [Accepted: 03/01/2017] [Indexed: 11/26/2022]
Abstract
The recycling of synaptic vesicle (SV) proteins and transmitter release occur at multiple sites along the axon. These processes are sensitive to inhibition of the small GTP binding protein ARF1, which regulates the adaptor protein 1 and 3 complex (AP-1/AP-3). As the axon matures, SV recycling becomes restricted to the presynaptic bouton, and its machinery undergoes a complex process of maturation. We used the styryl dye FM1-43 to highlight differences in the efficiency of membrane recycling at different sites in cerebellar granule cells cultured for 7 days in vitro. We used Brefeldin A (BFA) to inhibit AP-1/AP-3-mediated recycling and to test the contribution of this pathway to the heterogeneity of the responses when these cells are strongly stimulated. Combining imaging techniques and ultrastructural analyses, we found a significant decrease in the density of functional boutons and an increase in the presence of endosome-like structures within the boutons of cells incubated with BFA prior to FM1-43 loading. Such effects were not observed when BFA was added 5 min after the end of the loading step, when endocytosis was almost fully completed. In this situation, vesicles were found closer to the active zone (AZ) in boutons exposed to BFA. Together, these data suggest that the AP-1/AP-3 pathway contributes to SV recycling, affecting different steps in all boutons but not equally, and thus being partly responsible for the heterogeneity of the different recycling efficiencies. Cover Image for this issue: doi. 10.1111/jnc.13801.
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Affiliation(s)
- Alberto Rampérez
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - José Sánchez-Prieto
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - Magdalena Torres
- Departamento de Bioquímica y Biología Molecular, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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Synaptic Vesicle Endocytosis Occurs on Multiple Timescales and Is Mediated by Formin-Dependent Actin Assembly. Neuron 2017; 93:854-866.e4. [DOI: 10.1016/j.neuron.2017.02.011] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 12/12/2016] [Accepted: 01/23/2017] [Indexed: 11/21/2022]
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38
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Kyung JW, Cho IH, Lee S, Song WK, Ryan TA, Hoppa MB, Kim SH. Adaptor Protein 2 (AP-2) complex is essential for functional axogenesis in hippocampal neurons. Sci Rep 2017; 7:41620. [PMID: 28139716 PMCID: PMC5282494 DOI: 10.1038/srep41620] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 12/21/2016] [Indexed: 11/18/2022] Open
Abstract
The complexity and diversity of a neural network requires regulated elongation and branching of axons, as well as the formation of synapses between neurons. In the present study we explore the role of AP-2, a key endocytic adaptor protein complex, in the development of rat hippocampal neurons. We found that the loss of AP-2 during the early stage of development resulted in impaired axon extension and failed maturation of the axon initial segment (AIS). Normally the AIS performs two tasks in concert, stabilizing neural polarity and generating action potentials. In AP-2 silenced axons polarity is established, however there is a failure to establish action potential firing. Consequently, this impairs activity-driven Ca2+ influx and exocytosis at nerve terminals. In contrast, removal of AP-2 from older neurons does not impair axonal growth or signaling and synaptic function. Our data reveal that AP-2 has important roles in functional axogenesis by proper extension of axon as well as the formation of AIS during the early step of neurodevelopment.
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Affiliation(s)
- Jae Won Kyung
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul, 02447, South Korea
| | - In Ha Cho
- Department of Biology, Molecular Cellular Biology Program, Dartmouth College, Hanover, NH, 03755, USA
| | - Sukmook Lee
- Laboratory of Molecular Cancer Therapeutics, Scripps Korea Antibody Institute, Chuncheon, 24341, South Korea
| | - Woo Keun Song
- School of Life Science, Bioimaging Research Center, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, South Korea
| | - Timothy A Ryan
- Department of Biochemistry, Weill Cornell Medical College, New York, NY, 10065, USA
| | - Michael B Hoppa
- Department of Biology, Molecular Cellular Biology Program, Dartmouth College, Hanover, NH, 03755, USA
| | - Sung Hyun Kim
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul, 02447, South Korea.,Department of Physiology, Neurodegeneration Control Research Center, School of Medicine, Kyung Hee University, Seoul, 02447, South Korea
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39
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van Stegen B, Dagar S, Gottmann K. Release activity-dependent control of vesicle endocytosis by the synaptic adhesion molecule N-cadherin. Sci Rep 2017; 7:40865. [PMID: 28106089 PMCID: PMC5247765 DOI: 10.1038/srep40865] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 12/13/2016] [Indexed: 11/25/2022] Open
Abstract
At synapses in the mammalian brain, continuous information transfer requires the long-term maintenance of homeostatic coupling between exo- and endocytosis of synaptic vesicles. Because classical endocytosis is orders of magnitude slower than the millisecond-range exocytosis of vesicles, high frequency vesicle fusion could potentially compromise structural stability of synapses. However, the molecular mechanisms mediating the tight coupling of exo- and endocytosis are largely unknown. Here, we investigated the role of the transsynaptic adhesion molecules N-cadherin and Neuroligin1 in regulating vesicle exo- and endocytosis by using activity-induced FM4–64 staining and by using synaptophysin-pHluorin fluorescence imaging. The synaptic adhesion molecules N-cadherin and Neuroligin1 had distinct impacts on exo- and endocytosis at mature cortical synapses. Expression of Neuroligin1 enhanced vesicle release in a N-cadherin-dependent way. Most intriguingly, expression of N-cadherin enhanced both vesicle exo- and endocytosis. Further detailed analysis of N-cadherin knockout neurons revealed that the boosting of endocytosis by N-cadherin was largely dependent on preceding high levels of vesicle release activity. In summary, regulation of vesicle endocytosis was mediated at the molecular level by N-cadherin in a release activity-dependent manner. Because of its endocytosis enhancing function, N-cadherin might play an important role in the coupling of vesicle exo- and endocytosis.
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Affiliation(s)
- Bernd van Stegen
- Institute of Neuro- and Sensory Physiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Sushma Dagar
- Institute of Neuro- and Sensory Physiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Kurt Gottmann
- Institute of Neuro- and Sensory Physiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
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40
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Epsin1 modulates synaptic vesicle retrieval capacity at CNS synapses. Sci Rep 2016; 6:31997. [PMID: 27557559 PMCID: PMC4997357 DOI: 10.1038/srep31997] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/01/2016] [Indexed: 11/08/2022] Open
Abstract
Synaptic vesicle retrieval is an essential process for continuous maintenance of neural information flow after synaptic transmission. Epsin1, originally identified as an EPS15-interacting protein, is a major component of clathrin-mediated endocytosis. However, the role of Epsin1 in synaptic vesicle endocytosis at CNS synapses remains elusive. Here, we showed significantly altered synaptic vesicle endocytosis in neurons transfected with shRNA targeting Epsin1 during/after neural activity. Endocytosis was effectively restored by introducing shRNA-insensitive Epsin1 into Epsin1-depleted neurons. Domain studies performed on neurons in which domain deletion mutants of Epsin1 were introduced after Epsin1 knockdown revealed that ENTH, CLAP, and NPFs are essential for synaptic vesicle endocytosis, whereas UIMs are not. Strikingly, the efficacy of the rate of synaptic vesicle retrieval (the "endocytic capacity") was significantly decreased in the absence of Epsin1. Thus, Epsin1 is required for proper synaptic vesicle retrieval and modulates the endocytic capacity of synaptic vesicles.
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Endosome-mediated endocytic mechanism replenishes the majority of synaptic vesicles at mature CNS synapses in an activity-dependent manner. Sci Rep 2016; 6:31807. [PMID: 27534442 PMCID: PMC4989163 DOI: 10.1038/srep31807] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 07/26/2016] [Indexed: 11/30/2022] Open
Abstract
Whether synaptic vesicles (SVs) are recovered via endosome-mediated pathways is a matter of debate; however, recent evidence suggests that clathrin-independent bulk endocytosis (CIE) via endosomes is functional and preferentially replenishes SV pools during strong stimulation. Here, using brefeldin-A (BFA) to block CIE, we found that CIE retrieved a minority of SVs at developing CNS synapses during strong stimulation, but its contribution increased up to 61% at mature CNS synapses. Contrary to previous views, BFA not only blocked SV formation from the endosome but also blocked the endosome formation at the plasma membrane. Adaptor protein 1 and 3 (AP-1/3) have key roles in SV reformation from endosomes during CIE, and AP-1 also affects bulk endosome formation from the plasma membrane. Finally, temporary blocking of chronic or acute neuronal activity with tetrodotoxin in mature neurons redirected most SV retrieval to endosome-independent pathways. These results show that during high neuronal activity, CIE becomes the major endocytic pathway at mature CNS synapses. Moreover, mature neurons use clathrin-mediated endocytosis and the CIE pathway to different extents depending on their previous activity; this may result in activity-dependent alterations of the SV composition which ultimately influence transmitter release and contribute to synaptic plasticity.
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42
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Modes and mechanisms of synaptic vesicle recycling. Curr Opin Neurobiol 2016; 39:17-23. [DOI: 10.1016/j.conb.2016.03.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/02/2016] [Accepted: 03/07/2016] [Indexed: 11/30/2022]
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Bae JR, Kim SH. Impairment of SOD1-G93A motility is linked to mitochondrial movement in axons of hippocampal neurons. Arch Pharm Res 2016; 39:1144-50. [PMID: 27464601 DOI: 10.1007/s12272-016-0798-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 07/18/2016] [Indexed: 12/25/2022]
Abstract
Superoxide dismutase 1 (SOD1) is a well-known antioxidant enzyme. Mutation of SOD1 is closely associated with the pathogenesis of neurodegenerative disorders, such as amyotrophic lateral sclerosis and Alzheimer's disease. However, the pathologic pathways linking neurodegenerative diseases with mutation of SOD1 remain elusive. Here, we investigated the motility of SOD1-WT and -G93A (a pathogenic mutant of SOD1), and observed correlation of axonal transport of the mutant protein with mitochondria in primary cultured hippocampal neurons. The SOD1-G93A mutant showed significant accumulation at vGlut1-positive synaptic boutons and in cell bodies, compared to SOD1-WT. The proportions of motile WT and G93A proteins were similar (~30 %) while the motility velocity of SOD1-G93A was significantly slower (~40 %) than that of the WT counterpart. This motility defect of SOD1-G93A was highly correlated with mitochondrial movement. Our results collectively suggest that the SOD1-G93A mutant has a defect in motility that is linked to mitochondrial transport in axons.
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Affiliation(s)
- Jae Ryul Bae
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul, 130-701, South Korea
| | - Sung Hyun Kim
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul, 130-701, South Korea. .,Department of Physiology, School of Medicine, Neurodegeneration Control Research Center, Kyung Hee University, Seoul, 130-701, South Korea.
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σ2-Adaptin Facilitates Basal Synaptic Transmission and Is Required for Regenerating Endo-Exo Cycling Pool Under High-Frequency Nerve Stimulation in Drosophila. Genetics 2016; 203:369-85. [PMID: 26920756 DOI: 10.1534/genetics.115.183863] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 02/21/2016] [Indexed: 11/18/2022] Open
Abstract
The functional requirement of adapter protein 2 (AP2) complex in synaptic membrane retrieval by clathrin-mediated endocytosis is not fully understood. Here we isolated and functionally characterized a mutation that dramatically altered synaptic development. Based on the aberrant neuromuscular junction (NMJ) synapse, we named this mutation angur (a Hindi word meaning "grapes"). Loss-of-function alleles of angur show more than twofold overgrowth in bouton numbers and a dramatic decrease in bouton size. We mapped the angur mutation to σ2-adaptin, the smallest subunit of the AP2 complex. Reducing the neuronal level of any of the subunits of the AP2 complex or disrupting AP2 complex assembly in neurons phenocopied the σ2-adaptin mutation. Genetic perturbation of σ2-adaptin in neurons leads to a reversible temperature-sensitive paralysis at 38°. Electrophysiological analysis of the mutants revealed reduced evoked junction potentials and quantal content. Interestingly, high-frequency nerve stimulation caused prolonged synaptic fatigue at the NMJs. The synaptic levels of subunits of the AP2 complex and clathrin, but not other endocytic proteins, were reduced in the mutants. Moreover, bone morphogenetic protein (BMP)/transforming growth factor β (TGFβ) signaling was altered in these mutants and was restored by normalizing σ2-adaptin in neurons. Thus, our data suggest that (1) while σ2-adaptin facilitates synaptic vesicle (SV) recycling for basal synaptic transmission, its activity is also required for regenerating SVs during high-frequency nerve stimulation, and (2) σ2-adaptin regulates NMJ morphology by attenuating TGFβ signaling.
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Gordon SL, Cousin MA. The iTRAPs: Guardians of Synaptic Vesicle Cargo Retrieval During Endocytosis. Front Synaptic Neurosci 2016; 8:1. [PMID: 26903854 PMCID: PMC4746236 DOI: 10.3389/fnsyn.2016.00001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/25/2016] [Indexed: 11/30/2022] Open
Abstract
The reformation of synaptic vesicles (SVs) during endocytosis is essential for the maintenance of neurotransmission in central nerve terminals. Newly formed SVs must be generated with the correct protein cargo in the correct stoichiometry to be functional for exocytosis. Classical clathrin adaptor protein complexes play a key role in sorting and clustering synaptic vesicle cargo in this regard. However it is becoming increasingly apparent that additional “fail-safe” mechanisms exist to ensure the accurate retrieval of essential cargo molecules. For example, the monomeric adaptor proteins AP180/CALM and stonin-2 are required for the efficient retrieval of synaptobrevin II (sybII) and synaptotagmin-1 respectively. Furthermore, recent studies have revealed that sybII and synaptotagmin-1 interact with other SV cargoes to ensure a high fidelity of retrieval. These cargoes are synaptophysin (for sybII) and SV2A (for synaptotagmin-1). In this review, we summarize current knowledge regarding the retrieval mechanisms for both sybII and synaptotagmin-1 during endocytosis. We also define and set criteria for a new functional group of SV molecules that facilitate the retrieval of their interaction partners. We have termed these molecules intrinsic trafficking partners (iTRAPs) and we discuss how the function of this group impacts on presynaptic performance in both health and disease.
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Affiliation(s)
- Sarah L Gordon
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, VIC, Australia
| | - Michael A Cousin
- Centre for Integrative Physiology, University of Edinburgh Edinburgh, UK
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46
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Abstract
In the CNS (central nervous system), nerve cells communicate by transmitting signals from one to the next across chemical synapses. Electrical signals trigger controlled secretion of neurotransmitter by exocytosis of SV (synaptic vesicles) at the presynaptic site. Neurotransmitters diffuse across the synaptic cleft, activate receptor channels in the receiving neuron at the postsynaptic site, and thereby elicit a new electrical signal. Repetitive stimulation should result in fast depletion of fusion-competent SVs, given their limited number in the presynaptic bouton. Therefore, to support repeated rounds of release, a fast trafficking cycle is required that couples exocytosis and compensatory endocytosis. During this exo-endocytic cycle, a defined stoichiometry of SV proteins has to be preserved, that is, membrane proteins have to be sorted precisely. However, how this sorting is accomplished on a molecular level is poorly understood. In the present chapter we review recent findings regarding the molecular composition of SVs and the mechanisms that sort SV proteins during compensatory endocytosis. We identify self-assembly of SV components and individual cargo recognition by sorting adaptors as major mechanisms for maintenance of the SV protein complement.
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47
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Kim DH, Lee D, Chang EH, Kim JH, Hwang JW, Kim JY, Kyung JW, Kim SH, Oh JS, Shim SM, Na DL, Oh W, Chang JW. GDF-15 secreted from human umbilical cord blood mesenchymal stem cells delivered through the cerebrospinal fluid promotes hippocampal neurogenesis and synaptic activity in an Alzheimer's disease model. Stem Cells Dev 2015; 24:2378-90. [PMID: 26154268 DOI: 10.1089/scd.2014.0487] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Our previous studies demonstrated that transplantation of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) into the hippocampus of a transgenic mouse model of Alzheimer's disease (AD) reduced amyloid-β (Aβ) plaques and enhanced cognitive function through paracrine action. Due to the limited life span of hUCB-MSCs after their transplantation, the extension of hUCB-MSC efficacy was essential for AD treatment. In this study, we show that repeated cisterna magna injections of hUCB-MSCs activated endogenous hippocampal neurogenesis and significantly reduced Aβ42 levels. To identify the paracrine factors released from the hUCB-MSCs that stimulated endogenous hippocampal neurogenesis in the dentate gyrus, we cocultured adult mouse neural stem cells (NSCs) with hUCB-MSCs and analyzed the cocultured media with cytokine arrays. Growth differentiation factor-15 (GDF-15) levels were significantly increased in the media. GDF-15 suppression in hUCB-MSCs with GDF-15 small interfering RNA reduced the proliferation of NSCs in cocultures. Conversely, recombinant GDF-15 treatment in both in vitro and in vivo enhanced hippocampal NSC proliferation and neuronal differentiation. Repeated administration of hUBC-MSCs markedly promoted the expression of synaptic vesicle markers, including synaptophysin, which are downregulated in patients with AD. In addition, in vitro synaptic activity through GDF-15 was promoted. Taken together, these results indicated that repeated cisterna magna administration of hUCB-MSCs enhanced endogenous adult hippocampal neurogenesis and synaptic activity through a paracrine factor of GDF-15, suggesting a possible role of hUCB-MSCs in future treatment strategies for AD.
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Affiliation(s)
- Dong Hyun Kim
- 1 Biomedical Research Institute , MEDIPOST Co., Ltd., Gyeonggi-Do, Republic of Korea.,2 Department of Biotechnology and Bioengineering, Sungkyunkwan University , Suwon, Republic of Korea
| | - Dahm Lee
- 1 Biomedical Research Institute , MEDIPOST Co., Ltd., Gyeonggi-Do, Republic of Korea
| | - Eun Hyuk Chang
- 3 Samsung Biomedical Research Institute, Samsung Advanced Institute of Technology , Samsung Electronics Co., Ltd., Seoul, Republic of Korea.,4 Department of Neurology, Samsung Medical Center, School of Medicine, Sungkyunkwan University , Seoul, Republic of Korea
| | - Ji Hyun Kim
- 1 Biomedical Research Institute , MEDIPOST Co., Ltd., Gyeonggi-Do, Republic of Korea.,4 Department of Neurology, Samsung Medical Center, School of Medicine, Sungkyunkwan University , Seoul, Republic of Korea
| | - Jung Won Hwang
- 4 Department of Neurology, Samsung Medical Center, School of Medicine, Sungkyunkwan University , Seoul, Republic of Korea.,5 Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University , Seoul, Republic of Korea
| | - Ju-Yeon Kim
- 1 Biomedical Research Institute , MEDIPOST Co., Ltd., Gyeonggi-Do, Republic of Korea
| | - Jae Won Kyung
- 6 Department of Neuroscience, Neurodegeneration Control Research Center, School of Medicine, Kyung Hee University , Seoul, Republic of Korea
| | - Sung Hyun Kim
- 6 Department of Neuroscience, Neurodegeneration Control Research Center, School of Medicine, Kyung Hee University , Seoul, Republic of Korea
| | - Jeong Su Oh
- 2 Department of Biotechnology and Bioengineering, Sungkyunkwan University , Suwon, Republic of Korea
| | - Sang Mi Shim
- 7 Department of Biomedical Sciences, College of Medicine, Seoul National University , Seoul, Republic of Korea
| | - Duk Lyul Na
- 4 Department of Neurology, Samsung Medical Center, School of Medicine, Sungkyunkwan University , Seoul, Republic of Korea
| | - Wonil Oh
- 1 Biomedical Research Institute , MEDIPOST Co., Ltd., Gyeonggi-Do, Republic of Korea
| | - Jong Wook Chang
- 5 Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology (SAIHST), Sungkyunkwan University , Seoul, Republic of Korea.,8 Stem Cell & Regenerative Medicine Center (SCRMC), Research Institute for Future Medicine , Samsung Medical Center, Seoul, Republic of Korea
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Pan PY, Marrs J, Ryan TA. Vesicular glutamate transporter 1 orchestrates recruitment of other synaptic vesicle cargo proteins during synaptic vesicle recycling. J Biol Chem 2015. [PMID: 26224632 DOI: 10.1074/jbc.m115.651711] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A long standing question in synaptic physiology is how neurotransmitter-filled vesicles are rebuilt after exocytosis. Among the first steps in this process is the endocytic retrieval of the transmembrane proteins that are enriched in synaptic vesicles (SVs). At least six types of transmembrane proteins must be recovered, but the rules for how this multiple cargo selection is accomplished are poorly understood. Among these SV cargos is the vesicular glutamate transporter (vGlut). We show here that vGlut1 has a strong influence on the kinetics of retrieval of half of the known SV cargos and that specifically impairing the endocytosis of vGlut1 in turn slows down other SV cargos, demonstrating that cargo retrieval is a collective cargo-driven process. Finally, we demonstrate that different cargos can be retrieved in the same synapse with different kinetics, suggesting that additional post-endocytic sorting steps likely occur in the nerve terminal.
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Affiliation(s)
- Ping-Yue Pan
- From the Department of Biochemistry, Weill Cornell Medical College, New York, New York 10021
| | - Julia Marrs
- From the Department of Biochemistry, Weill Cornell Medical College, New York, New York 10021
| | - Timothy A Ryan
- From the Department of Biochemistry, Weill Cornell Medical College, New York, New York 10021
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49
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Di Giovanni J, Sheng ZH. Regulation of synaptic activity by snapin-mediated endolysosomal transport and sorting. EMBO J 2015; 34:2059-77. [PMID: 26108535 DOI: 10.15252/embj.201591125] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/29/2015] [Indexed: 11/09/2022] Open
Abstract
Recycling synaptic vesicles (SVs) transit through early endosomal sorting stations, which raises a fundamental question: are SVs sorted toward endolysosomal pathways? Here, we used snapin mutants as tools to assess how endolysosomal sorting and trafficking impact presynaptic activity in wild-type and snapin(-/-) neurons. Snapin acts as a dynein adaptor that mediates the retrograde transport of late endosomes (LEs) and interacts with dysbindin, a subunit of the endosomal sorting complex BLOC-1. Expressing dynein-binding defective snapin mutants induced SV accumulation at presynaptic terminals, mimicking the snapin(-/-) phenotype. Conversely, over-expressing snapin reduced SV pool size by enhancing SV trafficking to the endolysosomal pathway. Using a SV-targeted Ca(2+) sensor, we demonstrate that snapin-dysbindin interaction regulates SV positional priming through BLOC-1/AP-3-dependent sorting. Our study reveals a bipartite regulation of presynaptic activity by endolysosomal trafficking and sorting: LE transport regulates SV pool size, and BLOC-1/AP-3-dependent sorting fine-tunes the Ca(2+) sensitivity of SV release. Therefore, our study provides new mechanistic insights into the maintenance and regulation of SV pool size and synchronized SV fusion through snapin-mediated LE trafficking and endosomal sorting.
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Affiliation(s)
- Jerome Di Giovanni
- Synaptic Functions Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Zu-Hang Sheng
- Synaptic Functions Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
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50
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Phosphorylation of synaptic vesicle protein 2A at Thr84 by casein kinase 1 family kinases controls the specific retrieval of synaptotagmin-1. J Neurosci 2015; 35:2492-507. [PMID: 25673844 DOI: 10.1523/jneurosci.4248-14.2015] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Synaptic vesicle protein 2A (SV2A) is a ubiquitous component of synaptic vesicles (SVs). It has roles in both SV trafficking and neurotransmitter release. We demonstrate that Casein kinase 1 family members, including isoforms of Tau-tubulin protein kinases (TTBK1 and TTBK2), phosphorylate human SV2A at two constellations of residues, namely Cluster-1 (Ser42, Ser45, and Ser47) and Cluster-2 (Ser80, Ser81, and Thr84). These residues are also phosphorylated in vivo, and the phosphorylation of Thr84 within Cluster-2 is essential for triggering binding to the C2B domain of human synaptotagmin-1. We show by crystallographic and other analyses that the phosphorylated Thr84 residue binds to a pocket formed by three conserved Lys residues (Lys314, Lys326, and Lys328) on the surface of the synaptotagmin-1 C2B domain. Finally, we observed dysfunctional synaptotagmin-1 retrieval during SV endocytosis by ablating its phospho-dependent interaction with SV2A, knockdown of SV2A, or rescue with a phosphorylation-null Thr84 SV2A mutant in primary cultures of mouse neurons. This study reveals fundamental details of how phosphorylation of Thr84 on SV2A controls its interaction with synaptotagmin-1 and implicates SV2A as a phospho-dependent chaperone required for the specific retrieval of synaptotagmin-1 during SV endocytosis.
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