1
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Brodin L, Milovanovic D, Rizzoli SO, Shupliakov O. α-Synuclein in the Synaptic Vesicle Liquid Phase: Active Player or Passive Bystander? Front Mol Biosci 2022; 9:891508. [PMID: 35664678 PMCID: PMC9159372 DOI: 10.3389/fmolb.2022.891508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/26/2022] [Indexed: 12/15/2022] Open
Abstract
The protein α-synuclein, which is well-known for its links to Parkinson’s Disease, is associated with synaptic vesicles (SVs) in nerve terminals. Despite intensive studies, its precise physiological function remains elusive. Accumulating evidence indicates that liquid-liquid phase separation takes part in the assembly and/or maintenance of different synaptic compartments. The current review discusses recent data suggesting α-synuclein as a component of the SV liquid phase. We also consider possible implications of these data for disease.
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Affiliation(s)
- Lennart Brodin
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- *Correspondence: Lennart Brodin, ; Oleg Shupliakov,
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Silvio O. Rizzoli
- Institute of Neuro- and Sensory Physiology, University Medical Center Göttingen, Göttingen, Germany
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Institute of Translational Biomedicine, St. Petersburg University, St. Petersburg, Russia
- *Correspondence: Lennart Brodin, ; Oleg Shupliakov,
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2
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Llorens-Bobadilla E, Chell JM, Le Merre P, Wu Y, Zamboni M, Bergenstråhle J, Stenudd M, Sopova E, Lundeberg J, Shupliakov O, Carlén M, Frisén J. A latent lineage potential in resident neural stem cells enables spinal cord repair. Science 2020; 370:370/6512/eabb8795. [PMID: 33004487 DOI: 10.1126/science.abb8795] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 08/04/2020] [Indexed: 12/20/2022]
Abstract
Injuries to the central nervous system (CNS) are inefficiently repaired. Resident neural stem cells manifest a limited contribution to cell replacement. We have uncovered a latent potential in neural stem cells to replace large numbers of lost oligodendrocytes in the injured mouse spinal cord. Integrating multimodal single-cell analysis, we found that neural stem cells are in a permissive chromatin state that enables the unfolding of a normally latent gene expression program for oligodendrogenesis after injury. Ectopic expression of the transcription factor OLIG2 unveiled abundant stem cell-derived oligodendrogenesis, which followed the natural progression of oligodendrocyte differentiation, contributed to axon remyelination, and stimulated functional recovery of axon conduction. Recruitment of resident stem cells may thus serve as an alternative to cell transplantation after CNS injury.
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Affiliation(s)
- Enric Llorens-Bobadilla
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - James M Chell
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Pierre Le Merre
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Yicheng Wu
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Margherita Zamboni
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Joseph Bergenstråhle
- Science for Life Laboratory, Karolinska Institutet Science Park, SE-171 21 Solna, Sweden
| | - Moa Stenudd
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Elena Sopova
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Joakim Lundeberg
- Science for Life Laboratory, Karolinska Institutet Science Park, SE-171 21 Solna, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden.,Institute of Translational Biomedicine, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Marie Carlén
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden.,Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Huddinge, Sweden
| | - Jonas Frisén
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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3
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Pechstein A, Tomilin N, Fredrich K, Vorontsova O, Sopova E, Evergren E, Haucke V, Brodin L, Shupliakov O. Vesicle Clustering in a Living Synapse Depends on a Synapsin Region that Mediates Phase Separation. Cell Rep 2020; 30:2594-2602.e3. [DOI: 10.1016/j.celrep.2020.01.092] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/15/2019] [Accepted: 01/24/2020] [Indexed: 12/28/2022] Open
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4
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Shin W, Arpino G, Thiyagarajan S, Su R, McDargh ZA, Ge L, Guo X, Wei L, Shupliakov O, Jin AJ, O'Shaughnessy B, Wu LG. Vesicle Shrinking and Enlargement: The Yin and Yang of Exocytotic Content Release. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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5
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Shin W, Arpino G, Thiyagarajan S, Su R, Ge L, McDargh Z, Guo X, Wei L, Shupliakov O, Jin A, O'Shaughnessy B, Wu LG. Vesicle Shrinking and Enlargement Play Opposing Roles in the Release of Exocytotic Contents. Cell Rep 2020; 30:421-431.e7. [PMID: 31940486 PMCID: PMC7010319 DOI: 10.1016/j.celrep.2019.12.044] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/15/2019] [Accepted: 12/12/2019] [Indexed: 12/13/2022] Open
Abstract
For decades, two fusion modes were thought to control hormone and transmitter release essential to life; one facilitates release via fusion pore dilation and flattening (full collapse), and the other limits release by closing a narrow fusion pore (kiss-and-run). Using super-resolution stimulated emission depletion (STED) microscopy to visualize fusion modes of dense-core vesicles in neuroendocrine cells, we find that facilitation of release is mediated not by full collapse but by shrink fusion, in which the Ω-profile generated by vesicle fusion shrinks but maintains a large non-dilating pore. We discover that the physiological osmotic pressure of a cell squeezes, but does not dilate, the Ω-profile, which explains why shrink fusion prevails over full collapse. Instead of kiss-and-run, enlarge fusion, in which Ω-profiles grow while maintaining a narrow pore, slows down release. Shrink and enlarge fusion may thus account for diverse hormone and transmitter release kinetics observed in secretory cells, previously interpreted within the full-collapse/kiss-and-run framework.
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Affiliation(s)
- Wonchul Shin
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA; Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Sathish Thiyagarajan
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
| | - Rui Su
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
| | - Lihao Ge
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Zachary McDargh
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA
| | - Xiaoli Guo
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Lisi Wei
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden; Institute of Translational Biomedicine, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Albert Jin
- National Institute of Biomedical Imaging and Bioengineering (NIBIB), Bethesda, MD 20892, USA
| | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA.
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, 35 Convent Dr., Bldg. 35, Rm. 2B-1012, Bethesda, MD 20892, USA.
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6
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Abstract
The retromer complex mediates export of select transmembrane proteins from endosomes to the trans-Golgi network (TGN) or to the plasma membrane. Dysfunction of retromer has been linked with slowly progressing neurodegenerative disorders, including Alzheimer’s and Parkinson’s disease (AD and PD). As these disorders affect synapses it is of key importance to clarify the function of retromer-dependent protein trafficking pathways in pre- and postsynaptic compartments. Here we discuss recent insights into the roles of retromer in the trafficking of synaptic vesicle proteins, neurotransmitter receptors and other synaptic proteins. We also consider evidence that implies synapses as sites of early pathology in neurodegenerative disorders, pointing to a possible role of synaptic retromer dysfunction in the initiation of disease.
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Affiliation(s)
- Lennart Brodin
- Department of Neuroscience, Karolinska Institutet (KI), Stockholm, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet (KI), Stockholm, Sweden.,Institute of Translational Biomedicine, St. Petersburg University, St. Petersburg, Russia
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7
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Vorontsova OV, Akkuratov EE, Korenkova OM, Shupliakov O. Molecular Cloning of Synucleins in River Lamprey Lampetra fluviatilis. Biochem Moscow Suppl Ser A 2018. [DOI: 10.1134/s1990747818030108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Wen PJ, Grenklo S, Arpino G, Tan X, Liao HS, Heureaux J, Peng SY, Chiang HC, Hamid E, Zhao WD, Shin W, Näreoja T, Evergren E, Jin Y, Karlsson R, Ebert SN, Jin A, Liu AP, Shupliakov O, Wu LG. Actin dynamics provides membrane tension to merge fusing vesicles into the plasma membrane. Nat Commun 2016; 7:12604. [PMID: 27576662 PMCID: PMC5013665 DOI: 10.1038/ncomms12604] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 07/13/2016] [Indexed: 01/22/2023] Open
Abstract
Vesicle fusion is executed via formation of an Ω-shaped structure (Ω-profile), followed by closure (kiss-and-run) or merging of the Ω-profile into the plasma membrane (full fusion). Although Ω-profile closure limits release but recycles vesicles economically, Ω-profile merging facilitates release but couples to classical endocytosis for recycling. Despite its crucial role in determining exocytosis/endocytosis modes, how Ω-profile merging is mediated is poorly understood in endocrine cells and neurons containing small ∼30–300 nm vesicles. Here, using confocal and super-resolution STED imaging, force measurements, pharmacology and gene knockout, we show that dynamic assembly of filamentous actin, involving ATP hydrolysis, N-WASP and formin, mediates Ω-profile merging by providing sufficient plasma membrane tension to shrink the Ω-profile in neuroendocrine chromaffin cells containing ∼300 nm vesicles. Actin-directed compounds also induce Ω-profile accumulation at lamprey synaptic active zones, suggesting that actin may mediate Ω-profile merging at synapses. These results uncover molecular and biophysical mechanisms underlying Ω-profile merging. As vesicles fuse to the plasma membrane, they form intermediate Ω-shaped structures followed by either closure of the pore or full merging with the plasma membrane. Here Wen et al. show that dynamic actin assembly provides membrane tension to promote Ω merging in neuroendocrine cells and synapses.
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Affiliation(s)
- Peter J Wen
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Staffan Grenklo
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden.,Department of Cell Biology, WGI, Stockholm University, 106 91 Stockholm, Sweden
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA.,Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Xinyu Tan
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Hsien-Shun Liao
- National Institute of Biomedical Imaging and Bioengineering (NIBIB), Bethesda, Maryland 20892, USA
| | - Johanna Heureaux
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Shi-Yong Peng
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Hsueh-Cheng Chiang
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Edaeni Hamid
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Wei-Dong Zhao
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Wonchul Shin
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Tuomas Näreoja
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Emma Evergren
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Yinghui Jin
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Roger Karlsson
- Department of Cell Biology, WGI, Stockholm University, 106 91 Stockholm, Sweden
| | - Steven N Ebert
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, 6900 Lake Nona Boulevard, Orlando, Florida 32827, USA
| | - Albert Jin
- National Institute of Biomedical Imaging and Bioengineering (NIBIB), Bethesda, Maryland 20892, USA
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Oleg Shupliakov
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden.,Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
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9
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Winther ÅME, Vorontsova O, Rees KA, Näreoja T, Sopova E, Jiao W, Shupliakov O. An Endocytic Scaffolding Protein together with Synapsin Regulates Synaptic Vesicle Clustering in the Drosophila Neuromuscular Junction. J Neurosci 2015; 35:14756-70. [PMID: 26538647 PMCID: PMC6605226 DOI: 10.1523/jneurosci.1675-15.2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 09/16/2015] [Accepted: 09/25/2015] [Indexed: 11/21/2022] Open
Abstract
Many endocytic proteins accumulate in the reserve pool of synaptic vesicles (SVs) in synapses and relocalize to the endocytic periactive zone during neurotransmitter release. Currently little is known about their functions outside the periactive zone. Here we show that in the Drosophila neuromuscular junction (NMJ), the endocytic scaffolding protein Dap160 colocalizes during the SV cycle and forms a functional complex with the SV-associated phosphoprotein synapsin, previously implicated in SV clustering. This direct interaction is strongly enhanced under phosphorylation-promoting conditions and is essential for proper localization of synapsin at NMJs. In a dap160 rescue mutant lacking the interaction between Dap160 and synapsin, perturbed reclustering of SVs during synaptic activity is observed. Our data indicate that in addition to the function in endocytosis, Dap160 is a component of a network of protein-protein interactions that serves for clustering of SVs in conjunction with synapsin. During the SV cycle, Dap160 interacts with synapsin dispersed from SVs and helps direct synapsin back to vesicles. The proteins function in synergy to achieve efficient clustering of SVs in the reserve pool. SIGNIFICANCE STATEMENT We provide the first evidence for the function of the SH3 domain interaction in synaptic vesicle (SV) organization at the synaptic active zone. Using Drosophila neuromuscular junction as a model synapse, we describe the molecular mechanism that enables the protein implicated in SV clustering, synapsin, to return to the pool of vesicles during neurotransmitter release. We also identify the endocytic scaffolding complex that includes Dap160 as a regulator of the events linking exocytosis and endocytosis in synapses.
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Affiliation(s)
- Åsa M E Winther
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Olga Vorontsova
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Kathryn A Rees
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Tuomas Näreoja
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Elena Sopova
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Wei Jiao
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
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10
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Laguna A, Schintu N, Nobre A, Alvarsson A, Volakakis N, Jacobsen JK, Gómez-Galán M, Sopova E, Joodmardi E, Yoshitake T, Deng Q, Kehr J, Ericson J, Svenningsson P, Shupliakov O, Perlmann T. Dopaminergic control of autophagic-lysosomal function implicates Lmx1b in Parkinson's disease. Nat Neurosci 2015; 18:826-35. [PMID: 25915474 DOI: 10.1038/nn.4004] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 03/19/2015] [Indexed: 12/15/2022]
Abstract
The role of developmental transcription factors in maintenance of neuronal properties and in disease remains poorly understood. Lmx1a and Lmx1b are key transcription factors required for the early specification of ventral midbrain dopamine (mDA) neurons. Here we show that conditional ablation of Lmx1a and Lmx1b after mDA neuron specification resulted in abnormalities that show striking resemblance to early cellular abnormalities seen in Parkinson's disease. We found that Lmx1b was required for the normal execution of the autophagic-lysosomal pathway and for the integrity of dopaminergic nerve terminals and long-term mDA neuronal survival. Notably, human LMX1B expression was decreased in mDA neurons in brain tissue affected by Parkinson's disease. Thus, these results reveal a sustained and essential requirement of Lmx1b for the function of midbrain mDA neurons and suggest that its dysfunction is associated with Parkinson's disease pathogenesis.
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Affiliation(s)
- Ariadna Laguna
- 1] Ludwig Institute for Cancer Research, Stockholm, Sweden. [2] Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden. [3] Neurodegenerative Diseases Group, Vall d'Hebron Research Institute-CIBERNED, Barcelona, Spain
| | - Nicoletta Schintu
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - André Nobre
- Ludwig Institute for Cancer Research, Stockholm, Sweden
| | - Alexandra Alvarsson
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | | | | | - Marta Gómez-Galán
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Elena Sopova
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | | | - Takashi Yoshitake
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Qiaolin Deng
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Jan Kehr
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Johan Ericson
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Per Svenningsson
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Thomas Perlmann
- 1] Ludwig Institute for Cancer Research, Stockholm, Sweden. [2] Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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11
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Pechstein A, Gerth F, Milosevic I, Jäpel M, Eichhorn-Grünig M, Vorontsova O, Bacetic J, Maritzen T, Shupliakov O, Freund C, Haucke V. Vesicle uncoating regulated by SH3-SH3 domain-mediated complex formation between endophilin and intersectin at synapses. EMBO Rep 2014; 16:232-9. [PMID: 25520322 PMCID: PMC4328750 DOI: 10.15252/embr.201439260] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Neurotransmission involves the exo-endocytic cycling of synaptic vesicle (SV) membranes. Endocytic membrane retrieval and clathrin-mediated SV reformation require curvature-sensing and membrane-bending BAR domain proteins such as endophilin A. While their ability to sense and stabilize curved membranes facilitates membrane recruitment of BAR domain proteins, the precise mechanisms by which they are targeted to specific sites of SV recycling has remained unclear. Here, we demonstrate that the multi-domain scaffold intersectin 1 directly associates with endophilin A to facilitate vesicle uncoating at synapses. Knockout mice deficient in intersectin 1 accumulate clathrin-coated vesicles at synapses, a phenotype akin to loss of endophilin function. Intersectin 1/endophilin A1 complex formation is mediated by direct binding of the SH3B domain of intersectin to a non-canonical site on the SH3 domain of endophilin A1. Consistent with this, intersectin-binding defective mutant endophilin A1 fails to rescue clathrin accumulation at neuronal synapses derived from endophilin A1-3 triple knockout (TKO) mice. Our data support a model in which intersectin aids endophilin A recruitment to sites of clathrin-mediated SV recycling, thereby facilitating vesicle uncoating.
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Affiliation(s)
- Arndt Pechstein
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany Department of Neuroscience, DBRM, Karolinska Institutet, Stockholm, Sweden
| | - Fabian Gerth
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Ira Milosevic
- European Neuroscience Institute Göttingen (ENI-G), Synaptic Vesicle Dynamics Group, Göttingen, Germany
| | - Maria Jäpel
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | | | - Olga Vorontsova
- Department of Neuroscience, DBRM, Karolinska Institutet, Stockholm, Sweden
| | - Jelena Bacetic
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Tanja Maritzen
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Oleg Shupliakov
- Department of Neuroscience, DBRM, Karolinska Institutet, Stockholm, Sweden
| | - Christian Freund
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Volker Haucke
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany
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12
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Winther ÅME, Jiao W, Vorontsova O, Rees KA, Koh TW, Sopova E, Schulze KL, Bellen HJ, Shupliakov O. The dynamin-binding domains of Dap160/intersectin affect bulk membrane retrieval in synapses. J Cell Sci 2013; 126:1021-31. [PMID: 23321638 DOI: 10.1242/jcs.118968] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Dynamin-associated protein 160 kDa (Dap160)/intersectin interacts with several synaptic proteins and affects endocytosis and synapse development. The functional role of the different protein interaction domains is not well understood. Here we show that Drosophila Dap160 lacking the dynamin-binding SH3 domains does not affect the development of the neuromuscular junction but plays a key role in synaptic vesicle recycling. dap160 mutants lacking dynamin-interacting domains no longer accumulate dynamin properly at the periactive zone, and it becomes dispersed in the bouton during stimulation. This is accompanied by a reduction in uptake of the dye FM1-43 and an accumulation of large vesicles and membrane invaginations. However, we do not observe an increase in the number of clathrin-coated intermediates. We also note a depression in evoked excitatory junction potentials (EJPs) during high-rate stimulation, accompanied by aberrantly large miniature EJPs. The data reveal the important role of Dap160 in the targeting of dynamin to the periactive zone, where it is required to suppress bulk synaptic vesicle membrane retrieval during high-frequency activity.
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Affiliation(s)
- Åsa M E Winther
- Department of Neuroscience, DBRM, Karolinska Institutet, von Eulers väg 3, 171 77 Stockholm, Sweden
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13
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Leitinger G, Masich S, Neumüller J, Pabst MA, Pavelka M, Rind FC, Shupliakov O, Simmons PJ, Kolb D. Structural organization of the presynaptic density at identified synapses in the locust central nervous system. J Comp Neurol 2012; 520:384-400. [PMID: 21826661 PMCID: PMC3263340 DOI: 10.1002/cne.22744] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In a synaptic active zone, vesicles aggregate around a densely staining structure called the presynaptic density. We focus on its three-dimensional architecture and a major molecular component in the locust. We used electron tomography to study the presynaptic density in synapses made in the brain by identified second-order neuron of the ocelli. Here, vesicles close to the active zone are organized in two rows on either side of the presynaptic density, a level of organization not previously reported in insect central synapses. The row of vesicles that is closest to the density's base includes vesicles docked with the presynaptic membrane and thus presumably ready for release, whereas the outer row of vesicles does not include any that are docked. We show that a locust ortholog of the Drosophila protein Bruchpilot is localized to the presynaptic density, both in the ocellar pathway and compound eye visual neurons. An antibody recognizing the C-terminus of the Bruchpilot ortholog selectively labels filamentous extensions of the presynaptic density that reach out toward vesicles. Previous studies on Bruchpilot have focused on its role in neuromuscular junctions in Drosophila, and our study shows it is also a major functional component of presynaptic densities in the central nervous system of an evolutionarily distant insect. Our study thus reveals Bruchpilot executes similar functions in synapses that can sustain transmission of small graded potentials as well as those relaying large, spike-evoked signals.
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Affiliation(s)
- Gerd Leitinger
- Institute of Cell Biology, Histology and Embryology, Center for Molecular Medicine (ZMM), Medical University of Graz, Austria. Gerd.Leitinger@medunigraz
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14
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von Kleist L, Stahlschmidt W, Bulut H, Gromova K, Puchkov D, Robertson MJ, MacGregor KA, Tomilin N, Tomlin N, Pechstein A, Chau N, Chircop M, Sakoff J, von Kries JP, Saenger W, Kräusslich HG, Shupliakov O, Robinson PJ, McCluskey A, Haucke V. Role of the clathrin terminal domain in regulating coated pit dynamics revealed by small molecule inhibition. Cell 2011; 146:471-84. [PMID: 21816279 DOI: 10.1016/j.cell.2011.06.025] [Citation(s) in RCA: 394] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 05/06/2011] [Accepted: 06/14/2011] [Indexed: 01/19/2023]
Abstract
Clathrin-mediated endocytosis (CME) regulates many cell physiological processes such as the internalization of growth factors and receptors, entry of pathogens, and synaptic transmission. Within the endocytic network, clathrin functions as a central organizing platform for coated pit assembly and dissociation via its terminal domain (TD). We report the design and synthesis of two compounds named pitstops that selectively block endocytic ligand association with the clathrin TD as confirmed by X-ray crystallography. Pitstop-induced inhibition of clathrin TD function acutely interferes with receptor-mediated endocytosis, entry of HIV, and synaptic vesicle recycling. Endocytosis inhibition is caused by a dramatic increase in the lifetimes of clathrin coat components, including FCHo, clathrin, and dynamin, suggesting that the clathrin TD regulates coated pit dynamics. Pitstops provide new tools to address clathrin function in cell physiology with potential applications as inhibitors of virus and pathogen entry and as modulators of cell signaling.
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Affiliation(s)
- Lisa von Kleist
- Institute of Chemistry and Biochemistry & Neurocure Cluster of Excellence, Freie Universität Berlin, 14195 Berlin, Germany
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15
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von Kleist L, Stahlschmidt W, Bulut H, Gromova K, Puchkov D, Robertson M, MacGregor K, Tomilin N, Pechstein A, Chau N, Chircop M, Sakoff J, Peter von Kries J, Saenger W, Kräusslich HG, Shupliakov O, Robinson P, McCluskey A, Haucke V. Role of the Clathrin Terminal Domain in Regulating Coated Pit Dynamics Revealed by Small Molecule Inhibition. Cell 2011. [DOI: 10.1016/j.cell.2011.08.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Abstract
There is limited regeneration of lost tissue after central nervous system injury, and the lesion is sealed with a scar. The role of the scar, which often is referred to as the glial scar because of its abundance of astrocytes, is complex and has been discussed for more than a century. Here we show that a specific pericyte subtype gives rise to scar-forming stromal cells, which outnumber astrocytes, in the injured spinal cord. Blocking the generation of progeny by this pericyte subtype results in failure to seal the injured tissue. The formation of connective tissue is common to many injuries and pathologies, and here we demonstrate a cellular origin of fibrosis.
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Affiliation(s)
- Christian Göritz
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
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17
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Shupliakov O, Haucke V, Pechstein A. How synapsin I may cluster synaptic vesicles. Semin Cell Dev Biol 2011; 22:393-9. [DOI: 10.1016/j.semcdb.2011.07.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 07/13/2011] [Indexed: 12/14/2022]
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18
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Sundborger A, Soderblom C, Vorontsova O, Evergren E, Hinshaw JE, Shupliakov O. An endophilin-dynamin complex promotes budding of clathrin-coated vesicles during synaptic vesicle recycling. J Cell Sci 2011; 124:133-43. [PMID: 21172823 DOI: 10.1242/jcs.072686] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Clathrin-mediated vesicle recycling in synapses is maintained by a unique set of endocytic proteins and interactions. We show that endophilin localizes in the vesicle pool at rest and in spirals at the necks of clathrin-coated pits (CCPs) during activity in lamprey synapses. Endophilin and dynamin colocalize at the base of the clathrin coat. Protein spirals composed of these proteins on lipid tubes in vitro have a pitch similar to the one observed at necks of CCPs in living synapses, and lipid tubules are thinner than those formed by dynamin alone. Tubulation efficiency and the amount of dynamin recruited to lipid tubes are dramatically increased in the presence of endophilin. Blocking the interactions of the endophilin SH3 domain in situ reduces dynamin accumulation at the neck and prevents the formation of elongated necks observed in the presence of GTPγS. Therefore, endophilin recruits dynamin to a restricted part of the CCP neck, forming a complex, which promotes budding of new synaptic vesicles.
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Affiliation(s)
- Anna Sundborger
- Department of Neuroscience, DBRM, Karolinska Institutet, 17177 Stockholm, Sweden
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19
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Abstract
Central inter-neuronal synapses employ various molecular mechanisms to sustain neurotransmitter release during phases of high-frequency synaptic activity. One of the features ensuring this property is the presence of a pool of synaptic vesicles (SVs) in the presynaptic terminal. At rest and low rates of stimulation, most of the vesicles composing this pool remain in a tight cluster. They are actively utilized when neurons fire action potentials at higher rates and the capability of the recycling machinery is limited. In addition, SV clusters are capable of migrating between release sites and reassemble into clusters at neighboring active zones (AZs). Within the cluster, thin "tethers" interconnect SVs. These dynamic filamentous structures are reorganized during stimulation thereby releasing SVs from the cluster. So far, one protein family, the synapsins, which bind actin filaments and vesicles in a phosphorylation-dependent manner, has been implicated in SV clustering in vertebrate synapses. As evident from recent studies, many endocytic proteins reside in the SV cluster in addition to synapsin. Here we discuss alternative possible mechanisms involved in the organization of this population of SVs. We propose a model in which synapsins together with other synaptic proteins, a large proportion of which is involved in SV recycling, form a dynamic proteinaceous "matrix" which limits the mobility of SVs. Actin filaments, however, do not seem to contribute to SV crosslinking within the SV cluster, but instead they are present peripherally to it, at sites of neurotransmitter release, and at sites of SV recycling.
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Affiliation(s)
- Arndt Pechstein
- Department of Neuroscience, Developmental Biology for Regenerative Medicine, Karolinska Institutet Stockholm, Sweden
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20
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Jiao W, Masich S, Franzén O, Shupliakov O. Two pools of vesicles associated with the presynaptic cytosolic projection in Drosophila neuromuscular junctions. J Struct Biol 2010; 172:389-94. [PMID: 20678577 DOI: 10.1016/j.jsb.2010.07.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/19/2010] [Accepted: 07/24/2010] [Indexed: 10/19/2022]
Abstract
Synapses that sustain neurotransmitter release at high rates often contain special presynaptic cytosolic projections (PCPs) that are believed to facilitate synaptic vesicle (SV) movements to the sites of fusion. The genetically modifiable Drosophila neuromuscular junction (NMJ) serves as one of the model systems to investigate the functions of these structures. Using electron microscope tomography we determined the three-dimensional organization of the Drosophila PCP immobilized by high-pressure freezing, followed by cryo-substitution. We show that it is composed of three structural components: (1) the central core, (2) legs, organized in a regular grid at the bottom of the central core, and (3) cytoplasmic extensions. The extensions are comprised of thin filaments emerging from the central core. SVs connected to the extensions are either linked to the vesicles accumulated around the PCP or to the presynaptic membrane. This suggests that SVs associated with the PCP loose their connections with other vesicles in the cluster during translocation to the site of fusion.
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Affiliation(s)
- Wei Jiao
- Department of Neuroscience, DBRM, Karolinska Institutet, 17177 Stockholm, Sweden
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21
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Soderblom C, Stadler J, Jupille H, Blackstone C, Shupliakov O, Hanna MC. Targeted disruption of the Mast syndrome gene SPG21 in mice impairs hind limb function and alters axon branching in cultured cortical neurons. Neurogenetics 2010; 11:369-78. [PMID: 20661613 DOI: 10.1007/s10048-010-0252-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2010] [Accepted: 07/01/2010] [Indexed: 12/22/2022]
Abstract
Mast syndrome (SPG21) is a childhood-onset, autosomal recessive, complicated form of hereditary spastic paraplegia (HSP) characterized by dementia, thin corpus callosum, white matter abnormalities, and cerebellar and extrapyramidal signs in addition to spastic paraparesis. A nucleotide insertion resulting in premature truncation of the SPG21 gene product maspardin underlies this disorder, likely leading to loss of protein function. In this study, we generated SPG21-/- knockout mice by homologous recombination as a possible animal model for SPG21. Though SPG21-/- mice appeared normal at birth, within several months they developed gradually progressive hind limb dysfunction. Cerebral cortical neurons cultured from SPG21-/- mice exhibited significantly more axonal branching than neurons from wild-type animals, while comprehensive neuropathological analysis of SPG21-/- mice did not reveal definitive abnormalities. Since alterations in axon branching have been seen in neurons derived from animal models of other forms of HSP as well as motor neuron diseases, this may represent a common cellular pathogenic theme.
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Affiliation(s)
- Cynthia Soderblom
- National Institutes of Health-Karolinska Institutet Graduate Partnerships Program, 171 77, Stockholm, Sweden
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22
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Abstract
The synaptic vesicle is currently the most well-characterized cellular organelle. During neurotransmitter release it undergoes multiple cycles of exo- and endocytosis. Despite this the vesicle manages to retain its protein and lipid composition. How does this happen? Here we provide a brief overview of the molecular architecture of the synaptic vesicle, and discuss recent studies investigating single vesicle behavior and the mechanisms controlling the vesicle's molecular contents.
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Affiliation(s)
- Oleg Shupliakov
- Department of Neuroscience, DBRM, Karolinska Institutet, S-171 77 Stockholm, Sweden.
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23
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Zhao J, Liu T, Jin SB, Tomilin N, Castro J, Shupliakov O, Lendahl U, Nistér M. The novel conserved mitochondrial inner-membrane protein MTGM regulates mitochondrial morphology and cell proliferation. J Cell Sci 2009; 122:2252-62. [DOI: 10.1242/jcs.038513] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Although several proteins involved in mediating mitochondrial division have been reported in mammals, the mechanism of the fission machinery remains to be elucidated. Here, we identified a human nuclear gene (named MTGM) that encodes a novel, small, integral mitochondrial inner-membrane protein and shows high expression in both human brain tumor cell lines and tumor tissues. The gene is evolutionarily highly conserved, and its orthologs are 100% identical at the amino acid level in all analyzed mammalian species. The gene product is characterized by an unusual tetrad of the GxxxG motif in the transmembrane segment. Overexpression of MTGM (mitochondrial targeting GxxxG motif) protein results in mitochondrial fragmentation and release of mitochondrial Smac/Diablo to the cytosol with no effect on apoptosis. MTGM-induced mitochondrial fission can be blocked by a dominant negative Drp1 mutant (Drp1-K38A). Overexpression of MTGM also results in inhibition of cell proliferation, stalling of cells in S phase and nuclear accumulation of γ-H2AX. Knockdown of MTGM by RNA interference induces mitochondrial elongation, an increase of cell proliferation and inhibition of cell death induced by apoptotic stimuli. In conclusion, we suggest that MTGM is an integral mitochondrial inner-membrane protein that coordinately regulates mitochondrial morphology and cell proliferation.
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Affiliation(s)
- Jian Zhao
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden
| | - Tong Liu
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden
| | - Shao-Bo Jin
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Nikolay Tomilin
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Juan Castro
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Urban Lendahl
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Monica Nistér
- Department of Oncology-Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm, Sweden
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24
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Carlén M, Meletis K, Göritz C, Darsalia V, Evergren E, Tanigaki K, Amendola M, Barnabé-Heider F, Yeung MSY, Naldini L, Honjo T, Kokaia Z, Shupliakov O, Cassidy RM, Lindvall O, Frisén J. Forebrain ependymal cells are Notch-dependent and generate neuroblasts and astrocytes after stroke. Nat Neurosci 2009; 12:259-67. [PMID: 19234458 DOI: 10.1038/nn.2268] [Citation(s) in RCA: 381] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 01/07/2009] [Indexed: 02/06/2023]
Abstract
Neurons are continuously generated from stem cells in discrete regions in the adult mammalian brain. We found that ependymal cells lining the lateral ventricles were quiescent and did not contribute to adult neurogenesis under normal conditions in mice but instead gave rise to neuroblasts and astrocytes in response to stroke. Ependymal cell quiescence was actively maintained by canonical Notch signaling. Inhibition of this pathway in uninjured animals allowed ependymal cells to enter the cell cycle and produce olfactory bulb neurons, whereas forced Notch signaling was sufficient to block the ependymal cell response to stroke. Ependymal cells were depleted by stroke and failed to self-renew sufficiently to maintain their own population. Thus, although ependymal cells act as primary cells in the neural lineage to produce neurons and glial cells after stroke, they do not fulfill defining criteria for stem cells under these conditions and instead serve as a reservoir that is recruited by injury.
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Affiliation(s)
- Marie Carlén
- Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, SE-171 77 Stockholm, Sweden
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25
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Owe SG, Jensen V, Evergren E, Ruiz A, Shupliakov O, Kullmann DM, Storm-Mathisen J, Walaas SI, Hvalby Ø, Bergersen LH. Synapsin- and actin-dependent frequency enhancement in mouse hippocampal mossy fiber synapses. Cereb Cortex 2008; 19:511-23. [PMID: 18550596 PMCID: PMC2638812 DOI: 10.1093/cercor/bhn101] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The synapsin proteins have different roles in excitatory and inhibitory synaptic terminals. We demonstrate a differential role between types of excitatory terminals. Structural and functional aspects of the hippocampal mossy fiber (MF) synapses were studied in wild-type (WT) mice and in synapsin double-knockout mice (DKO). A severe reduction in the number of synaptic vesicles situated more than 100 nm away from the presynaptic membrane active zone was found in the synapsin DKO animals. The ultrastructural level gave concomitant reduction in F-actin immunoreactivity observed at the periactive endocytic zone of the MF terminals. Frequency facilitation was normal in synapsin DKO mice at low firing rates (approximately 0.1 Hz) but was impaired at firing rates within the physiological range (approximately 2 Hz). Synapses made by associational/commissural fibers showed comparatively small frequency facilitation at the same frequencies. Synapsin-dependent facilitation in MF synapses of WT mice was attenuated by blocking F-actin polymerization with cytochalasin B in hippocampal slices. Synapsin III, selectively seen in MF synapses, is enriched specifically in the area adjacent to the synaptic cleft. This may underlie the ability of synapsin III to promote synaptic depression, contributing to the reduced frequency facilitation observed in the absence of synapsins I and II.
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Affiliation(s)
- Simen G Owe
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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26
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Wallis K, Sjögren M, van Hogerlinden M, Silberberg G, Fisahn A, Nordström K, Larsson L, Westerblad H, Morreale de Escobar G, Shupliakov O, Vennström B. Locomotor deficiencies and aberrant development of subtype-specific GABAergic interneurons caused by an unliganded thyroid hormone receptor alpha1. J Neurosci 2008; 28:1904-15. [PMID: 18287507 PMCID: PMC6671444 DOI: 10.1523/jneurosci.5163-07.2008] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 01/06/2007] [Accepted: 01/06/2008] [Indexed: 01/15/2023] Open
Abstract
Thyroid hormone (TH) deficiency during development causes severe and permanent neuronal damage, but the primary insult at the tissue level has remained unsolved. We have defined locomotor deficiencies in mice caused by a mutant thyroid hormone receptor alpha1 (TR alpha1) with potent aporeceptor activity attributable to reduced affinity to TH. This allowed identification of distinct functions that required either maternal supply of TH during early embryonic development or sufficient innate levels of hormone during late fetal development. In both instances, continued exposure to high levels of TH after birth and throughout life was needed. The hormonal dependencies correlated with severely delayed appearance of parvalbumin-immunoreactive GABAergic interneurons and increased numbers of calretinin-immunoreactive cells in the neocortex. This resulted in reduced numbers of fast spiking interneurons and defects in cortical network activity. The identification of locomotor deficiencies caused by insufficient supply of TH during fetal/perinatal development and their correlation with subtype-specific interneurons suggest a previously unknown basis for the neuronal consequences of endemic cretinism and untreated congenital hypothyroidism, and specifies TR alpha1 as the receptor isoform mediating these effects.
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Affiliation(s)
| | | | | | | | | | | | - Lars Larsson
- Department of Neuroscience, Uppsala University, SE-751 24 Uppsala, Sweden, and
| | - Håkan Westerblad
- Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Gabriela Morreale de Escobar
- Instituto de Investigaciones Biomédicas “Alberto Sols,” Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid and Center for Biomedical Research on Rare Diseases, 28029 Madrid, Spain
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27
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Abstract
Although the synapsin phosphoproteins were discovered more than 30 years ago and are known to play important roles in neurotransmitter release and synaptogenesis, a complete picture of their functions within the nerve terminal is lacking. It has been shown that these proteins play an important role in the clustering of synaptic vesicles (SVs) at active zones and function as modulators of synaptic strength by acting at both pre- and postdocking levels. Recent studies have demonstrated that synapsins migrate to the endocytic zone of central synapses during neurotransmitter release, which suggests that there are additional functions for these proteins in SV recycling.
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Affiliation(s)
- E Evergren
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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28
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Koh TW, Korolchuk VI, Wairkar YP, Jiao W, Evergren E, Pan H, Zhou Y, Venken KJT, Shupliakov O, Robinson IM, O'Kane CJ, Bellen HJ. Eps15 and Dap160 control synaptic vesicle membrane retrieval and synapse development. ACTA ACUST UNITED AC 2007; 178:309-22. [PMID: 17620409 PMCID: PMC2064449 DOI: 10.1083/jcb.200701030] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epidermal growth factor receptor pathway substrate clone 15 (Eps15) is a protein implicated in endocytosis, endosomal protein sorting, and cytoskeletal organization. Its role is, however, still unclear, because of reasons including limitations of dominant-negative experiments and apparent redundancy with other endocytic proteins. We generated Drosophila eps15-null mutants and show that Eps15 is required for proper synaptic bouton development and normal levels of synaptic vesicle (SV) endocytosis. Consistent with a role in SV endocytosis, Eps15 moves from the center of synaptic boutons to the periphery in response to synaptic activity. The endocytic protein, Dap160/intersectin, is a major binding partner of Eps15, and eps15 mutants phenotypically resemble dap160 mutants. Analyses of eps15 dap160 double mutants suggest that Eps15 functions in concert with Dap160 during SV endocytosis. Based on these data, we hypothesize that Eps15 and Dap160 promote the efficiency of endocytosis from the plasma membrane by maintaining high concentrations of multiple endocytic proteins, including dynamin, at synapses.
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Affiliation(s)
- Tong-Wey Koh
- Graduate Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
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29
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Evergren E, Gad H, Walther K, Sundborger A, Tomilin N, Shupliakov O. Intersectin is a negative regulator of dynamin recruitment to the synaptic endocytic zone in the central synapse. J Neurosci 2007; 27:379-90. [PMID: 17215399 PMCID: PMC6672076 DOI: 10.1523/jneurosci.4683-06.2007] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 11/27/2006] [Accepted: 11/27/2006] [Indexed: 11/21/2022] Open
Abstract
Intersectin is a multidomain dynamin-binding protein implicated in numerous functions in the nervous system, including synapse formation and endocytosis. Here, we demonstrate that during neurotransmitter release in the central synapse, intersectin, like its binding partner dynamin, is redistributed from the synaptic vesicle pool to the periactive zone. Acute perturbation of the intersectin-dynamin interaction by microinjection of either intersectin antibodies or Src homology 3 (SH3) domains inhibited endocytosis at the fission step. Although the morphological effects induced by the different reagents were similar, antibody injections resulted in a dramatic increase in dynamin immunoreactivity around coated pits and at constricted necks, whereas synapses microinjected with the GST (glutathione S-transferase)-SH3C domain displayed reduced amounts of dynamin in the neck region. Our data suggest that intersectin controls the amount of dynamin released from the synaptic vesicle cluster to the periactive zone and that it may regulate fission of clathrin-coated intermediates.
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Affiliation(s)
- Emma Evergren
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Helge Gad
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Kristin Walther
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Anna Sundborger
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Nikolay Tomilin
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
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30
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Brodin L, Shupliakov O. Giant reticulospinal synapse in lamprey: molecular links between active and periactive zones. Cell Tissue Res 2006; 326:301-10. [PMID: 16786368 DOI: 10.1007/s00441-006-0216-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2006] [Accepted: 04/20/2006] [Indexed: 10/24/2022]
Abstract
Deciphering the function of synaptic release sites is central to understanding neuronal communication. Here, we review studies of the lamprey giant reticulospinal synapse, a model that can be used to dissect synaptic vesicle trafficking at single release sites. The presynaptic axon is large and contains active zones that are spatially separated from each other. During activity, synaptic vesicle membrane is shuttled between the active zone and the periactive zone at which endocytosis occurs. Recent studies have shown that the periactive zone contains an actin-rich cytomatrix that expands during synaptic activity. This cytomatrix has been implicated in multiple functions that include (1) activity-dependent trafficking of proteins between the synaptic vesicle cluster and the periactive zone, (2) synaptic vesicle endocytosis, and (3) the movement of newly formed synaptic vesicles to the vesicle cluster. The actin cytomatrix thus provides a link between the active zone and the periactive zone; this link appears to be critical for sustained cycling of synaptic vesicles.
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Affiliation(s)
- Lennart Brodin
- Department of Neuroscience, CEDB, Karolinska Institutet, S-17177 Stockholm, Sweden.
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31
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Masich S, Ostberg T, Norlén L, Shupliakov O, Daneholt B. A procedure to deposit fiducial markers on vitreous cryo-sections for cellular tomography. J Struct Biol 2006; 156:461-8. [PMID: 16859924 DOI: 10.1016/j.jsb.2006.05.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2006] [Revised: 05/29/2006] [Accepted: 05/31/2006] [Indexed: 11/21/2022]
Abstract
We describe a novel approach for the accurate alignment of images in electron tomography of vitreous cryo-sections. Quantum dots, suspended in organic solvents at cryo-temperatures, are applied directly onto the sections and are subsequently used as fiducial markers to align the tilt series. Data collection can be performed from different regions of the vitreous sections, even when the sections touch the grid only at a few places. We present high-resolution tomograms of some organelles in cryo-sections of human skin cells using this method. The average error in image alignment was about 1nm and the resolution was estimated to be 5-7nm. Thus, the use of section-attached quantum dots as fiducial markers in electron tomography of vitreous cryo-sections facilitates high-resolution in situ 3D imaging of organelles and macromolecular complexes in their native hydrated state.
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Affiliation(s)
- Sergej Masich
- Department of Cell and Molecular Biology, Karolinska Institutet, Box 285, SE-17177 Stockholm, Sweden
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32
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Kropotov A, Gogvadze V, Shupliakov O, Tomilin N, Serikov VB, Tomilin NV, Zhivotovsky B. Peroxiredoxin V is essential for protection against apoptosis in human lung carcinoma cells. Exp Cell Res 2006; 312:2806-15. [PMID: 16781710 DOI: 10.1016/j.yexcr.2006.05.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 05/06/2006] [Accepted: 05/12/2006] [Indexed: 10/24/2022]
Abstract
Sensitivity of tumor cells to treatment with anticancer drugs depends on expression and function of antiapoptotic and antioxidant proteins. The goal of our study was to determine the functional role of the novel antioxidant protein Peroxiredoxin V (PrxV), in protection of human lung carcinoma cell lines against apoptosis. Analysis of expression of PrxV in multiple lung carcinoma cell lines revealed a positive correlation between the expression of PrxV and radioresistance in vitro. Clones of the lung carcinoma cells U1810 with down-regulated expression of PrxV, or with its impaired enzymatic function (expression of redox-negative PrxV), demonstrated increased sensitivity to treatment with anticancer drugs etoposide and adriamycin. Pre-treatment of these clones with antioxidant N-acetyl-cysteine did not change their sensitivity to adriamycin, suggesting the involvement of a non-redox activity of PrxV. Expression of the redox-negative PrxV mainly affected the mitochondrial pathway of apoptosis, as assessed by cytochrome c release assay. Impairment of the PrxV enzymatic function also affected transmembrane potential and calcium loading capacity of mitochondria, as well as mitochondrial morphology. Altogether, these findings suggest that PrxV is a multifunctional protein, which is essential for protection against apoptosis induced by anticancer drugs.
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Affiliation(s)
- Andrey Kropotov
- Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA.
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Evergren E, Zotova E, Brodin L, Shupliakov O. Differential efficiency of the endocytic machinery in tonic and phasic synapses. Neuroscience 2006; 141:123-31. [PMID: 16675130 DOI: 10.1016/j.neuroscience.2006.03.038] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 03/16/2006] [Accepted: 03/22/2006] [Indexed: 11/29/2022]
Abstract
Efficient synaptic vesicle membrane recycling is one of the key factors required to sustain neurotransmission. We investigated potential differences in the compensatory endocytic machineries in two glutamatergic synapses with phasic and tonic patterns of activity in the lamprey spinal cord. Post-embedding immunocytochemistry demonstrated that proteins involved in synaptic vesicle recycling, including dynamin, intersectin, and synapsin, occur at higher levels (labeling per vesicle) in tonic dorsal column synapses than in phasic reticulospinal synapses. Synaptic vesicle protein 2 occurred at similar levels in the two types of synapse. After challenging the synapses with high potassium stimulation for 30 min the vesicle pool in the tonic synapse was maintained at a normal level, while that in the phasic synapse was partly depleted along with expansion of the plasma membrane and accumulation of clathrin-coated intermediates at the periactive zone. Thus, our results indicate that an increased efficiency of the endocytic machinery in a synapse may be one of the factors underlying the ability to sustain neurotransmission at high rates.
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Affiliation(s)
- E Evergren
- Department of Neuroscience, Center of Excellence in Developmental Biology, Karolinska Institutet, 171 77 Stockholm, Sweden
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Evergren E, Marcucci M, Tomilin N, Löw P, Slepnev V, Andersson F, Gad H, Brodin L, De Camilli P, Shupliakov O. Amphiphysin is a component of clathrin coats formed during synaptic vesicle recycling at the lamprey giant synapse. Traffic 2005; 5:514-28. [PMID: 15180828 DOI: 10.1111/j.1398-9219.2004.00198.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Amphiphysin is a protein enriched at mammalian synapses thought to function as a clathrin accessory factor in synaptic vesicle endocytosis. Here we examine the involvement of amphiphysin in synaptic vesicle recycling at the giant synapse in the lamprey. We show that amphiphysin resides in the synaptic vesicle cluster at rest and relocates to sites of endocytosis during synaptic activity. It accumulates at coated pits where its SH3 domain, but not its central clathrin/AP-2-binding (CLAP) region, is accessible for antibody binding. Microinjection of antibodies specifically directed against the CLAP region inhibited recycling of synaptic vesicles and caused accumulation of clathrin-coated intermediates with distorted morphology, including flat patches of coated presynaptic membrane. Our data provide evidence for an activity-dependent redistribution of amphiphysin in intact nerve terminals and show that amphiphysin is a component of presynaptic clathrin-coated intermediates formed during synaptic vesicle recycling.
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Affiliation(s)
- Emma Evergren
- Laboratory of Neuronal Membrane Trafficking, Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
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35
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Abstract
The endocytosis of membrane receptors is a complex and tightly controlled process that is essential for maintaining cellular homoeostasis. The removal of receptors from the cell surface can be constitutive or ligand-induced, and occurs in a clathrin-dependent or -independent manner. The recruitment of receptors into specialized membrane domains, the formation of vesicles and the trafficking of receptors together with their ligands within endocytic compartments are regulated by reversible protein modifications, and multiple protein-protein and protein-lipid interactions. Recent reports describe a variety of multidomain molecules that facilitate receptor endocytosis and function as platforms for the assembly of protein complexes. These scaffold proteins typically act in a cargo-specific manner, recognizing one or more receptor types, or function at the level of endocytic cellular microcompartments by controlling the movement of cargo molecules and linking endocytic machineries to signalling pathways. In the present review we summarize present knowledge on endocytic scaffold molecules and discuss their functions.
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Key Words
- cargo
- endocytosis
- microcompartment
- scaffold
- alix, alg-2 (apoptosis-linked gene 2)-interacting protein x
- anth domain, ap180 n-terminal homology domain
- ap-2, adaptor protein-2
- arh, autosomal recessive hypercholesterolaemia
- bar domain, bin/amphiphysin/rvs domain
- cd2ap, cd2-associated protein
- cin85, cbl-interacting protein of 85 kda
- dab2, disabled-2
- eea1, early endosome antigen 1
- egfr, epidermal growth factor receptor
- eh domain, eps15 homology domain
- enth domain, epsin n-terminal homology domain
- escrt, endosomal sorting complexes required for transport
- fyve, fab1p, yotb, vac1p and eea1
- gap, gtpase-activating protein
- gpcr, g-protein-coupled receptor
- hrs, hepatocyte growth factor-regulated tyrosine kinase substrate
- lbpa, lysobiphosphatidic acid
- ldl, low-density lipoprotein
- lnx, ligand of numb protein x
- mvb, multivesicular body
- nak, numb-associated kinase
- nsf, n-ethylmaleimide-sensitive fusion protein
- pon, partner of numb
- ptb domain, phosphotyrosine-binding domain
- rtk, receptor tyrosine kinase
- sh3, src homology 3
- snare, soluble nsf attachment protein receptor
- stam, signal-transducing adaptor molecule
- tcr, t-cell receptor
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Affiliation(s)
- Iwona Szymkiewicz
- *Institute of Biochemistry II, Goethe University Medical School, 60590 Frankfurt, Germany
| | - Oleg Shupliakov
- †Department of Neuroscience, CEDB, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Ivan Dikic
- *Institute of Biochemistry II, Goethe University Medical School, 60590 Frankfurt, Germany
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Evergren E, Tomilin N, Vasylieva E, Sergeeva V, Bloom O, Gad H, Capani F, Shupliakov O. A pre-embedding immunogold approach for detection of synaptic endocytic proteins in situ. J Neurosci Methods 2004; 135:169-74. [PMID: 15020101 DOI: 10.1016/j.jneumeth.2003.12.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Revised: 11/22/2003] [Accepted: 12/17/2003] [Indexed: 10/26/2022]
Abstract
During the past decade, many molecular components of clathrin-mediated endocytosis have been identified and proposed to play various hypothetical roles in the process [Nat. Rev. Neurosci. 1 (2000) 161; Nature 422 (2003) 37]. One limitation to the evaluation of these hypotheses is the efficiency and resolution of immunolocalization protocols currently in use. In order to facilitate the evaluation of these hypotheses and to understand more fully the molecular mechanisms of clathrin-mediated endocytosis, we have developed a protocol allowing enhanced and reliable subcellular immunolocalization of proteins in synaptic endocytic zones in situ. Synapses established by giant reticulospinal axons in lamprey are used as a model system for these experiments. These axons are unbranched and reach up to 80-100 microm in diameter. Synaptic active zones and surrounding endocytic zones are established on the surface of the axonal cylinder. To provide access for antibodies to the sites of synaptic vesicle recycling, axons are lightly fixed and cut along their longitudinal axis. To preserve the ultrastructure of the synaptic endocytic zone, antibodies are applied without the addition of detergents. Opened axons are incubated with primary antibodies, which are detected with secondary antibodies conjugated to gold particles. Specimens are then post-fixed and processed for electron microscopy. This approach allows preservation of the ultrastructure of the endocytic sites during immunolabeling procedures, while simultaneously achieving reliable immunogold detection of proteins on endocytic intermediates. To explore the utility of this approach, we have investigated the localization of a GTPase, dynamin, on clathrin-coated intermediates in the endocytic zone of the lamprey giant synapse. Using the present immunogold protocol, we confirm the presence of dynamin on late stage coated pits [Nature 422 (2003) 37] and also demonstrate that dynamin is recruited to the coat of endocytic intermediates from the very early stages of the clathrin coat formation. Thus, our experiments show that the current pre-embedding immunogold method is a useful experimental tool to study the molecular mechanisms of synaptic vesicle recycling.
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Affiliation(s)
- Emma Evergren
- Laboratory of Neuronal Membrane Trafficking, Department of Neuroscience, Karolinska Institutet, Center of Excellence in Developmental Biology, Stockholm, Sweden
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37
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Zhao M, Momma S, Delfani K, Carlen M, Cassidy RM, Johansson CB, Brismar H, Shupliakov O, Frisen J, Janson AM. Evidence for neurogenesis in the adult mammalian substantia nigra. Proc Natl Acad Sci U S A 2003; 100:7925-30. [PMID: 12792021 PMCID: PMC164689 DOI: 10.1073/pnas.1131955100] [Citation(s) in RCA: 396] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2002] [Indexed: 01/23/2023] Open
Abstract
New neurons are generated from stem cells in a few regions of the adult mammalian brain. Here we provide evidence for the generation of dopaminergic projection neurons of the type that are lost in Parkinson's disease from stem cells in the adult rodent brain and show that the rate of neurogenesis is increased after a lesion. The number of new neurons generated under physiological conditions in substantia nigra pars compacta was found to be several orders of magnitude smaller than in the granular cell layer of the dentate gyrus of the hippocampus. However, if the rate of neuronal turnover is constant, the entire population of dopaminergic neurons in substantia nigra could be replaced during the lifespan of a mouse. These data indicate that neurogenesis in the adult brain is more widespread than previously thought and may have implications for our understanding of the pathogenesis and treatment of neurodegenerative disorders such as Parkinson's disease.
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Affiliation(s)
- Ming Zhao
- Departments of Neuroscience, Cell and Molecular Biology, Medical Nobel Institute, and Woman and Child Health, Karolinska Institute, SE-171 77 Stockholm, Sweden
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38
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Bloom O, Evergren E, Tomilin N, Kjaerulff O, Löw P, Brodin L, Pieribone VA, Greengard P, Shupliakov O. Colocalization of synapsin and actin during synaptic vesicle recycling. J Cell Biol 2003; 161:737-47. [PMID: 12756235 PMCID: PMC2199372 DOI: 10.1083/jcb.200212140] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2002] [Revised: 04/16/2003] [Accepted: 04/16/2003] [Indexed: 01/21/2023] Open
Abstract
It has been hypothesized that in the mature nerve terminal, interactions between synapsin and actin regulate the clustering of synaptic vesicles and the availability of vesicles for release during synaptic activity. Here, we have used immunogold electron microscopy to examine the subcellular localization of actin and synapsin in the giant synapse in lamprey at different states of synaptic activity. In agreement with earlier observations, in synapses at rest, synapsin immunoreactivity was preferentially localized to a portion of the vesicle cluster distal to the active zone. During synaptic activity, however, synapsin was detected in the pool of vesicles proximal to the active zone. In addition, actin and synapsin were found colocalized in a dynamic filamentous cytomatrix at the sites of synaptic vesicle recycling, endocytic zones. Synapsin immunolabeling was not associated with clathrin-coated intermediates but was found on vesicles that appeared to be recycling back to the cluster. Disruption of synapsin function by microinjection of antisynapsin antibodies resulted in a prominent reduction of the cytomatrix at endocytic zones of active synapses. Our data suggest that in addition to its known function in clustering of vesicles in the reserve pool, synapsin migrates from the synaptic vesicle cluster and participates in the organization of the actin-rich cytomatrix in the endocytic zone during synaptic activity.
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Affiliation(s)
- Ona Bloom
- The Rockefeller University, New York, NY 10021, USA.
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39
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Shupliakov O, Bloom O, Gustafsson JS, Kjaerulff O, Low P, Tomilin N, Pieribone VA, Greengard P, Brodin L. Impaired recycling of synaptic vesicles after acute perturbation of the presynaptic actin cytoskeleton. Proc Natl Acad Sci U S A 2002; 99:14476-81. [PMID: 12381791 PMCID: PMC137908 DOI: 10.1073/pnas.212381799] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Actin is an abundant component of nerve terminals that has been implicated at multiple steps of the synaptic vesicle cycle, including reversible anchoring, exocytosis, and recycling of synaptic vesicles. In the present study we used the lamprey reticulospinal synapse to examine the role of actin at the site of synaptic vesicle recycling, the endocytic zone. Compounds interfering with actin function, including phalloidin, the catalytic subunit of Clostridium botulinum C2 toxin, and N-ethylmaleimide-treated myosin S1 fragments were microinjected into the axon. In unstimulated, phalloidin-injected axons actin filaments formed a thin cytomatrix adjacent to the plasma membrane around the synaptic vesicle cluster. The filaments proliferated after stimulation and extended toward the vesicle cluster. Synaptic vesicles were tethered along the filaments. Injection of N-ethylmaleimide-treated myosin S1 fragments caused accumulation of aggregates of synaptic vesicles between the endocytic zone and the vesicle cluster, suggesting that vesicle transport was inhibited. Phalloidin, as well as C2 toxin, also caused changes in the structure of clathrin-coated pits in stimulated synapses. Our data provide evidence for a critical role of actin in recycling of synaptic vesicles, which seems to involve functions both in endocytosis and in the transport of recycled vesicles to the synaptic vesicle cluster.
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Affiliation(s)
- Oleg Shupliakov
- Nobel Institute for Neurophysiology, Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
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40
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Abstract
In most parts of the adult mammalian central nervous system cell division is a relatively rare event, which makes it difficult to study at the ultrastructural level. We designed a protocol for reliable ultrastructural identification of proliferating cells in a tissue volume using DNA-incorporated 5-bromo-2-deoxyuridine (BrdU) as a marker. After BrdU administration the tissue is fixed and embedded in hydrophilic resin (LR Gold) and then cut in serial 1-2 microm sections and mounted on glass slides. BrdU is detected at the light microscopic level using immunogold labeling followed by silver enhancement, according to a standard procedure. After detection of labeled nuclei the section is reembedded in resin on the same glass slide. The glass is then dissolved in hydrofluoric acid and labeled cells cut in ultrathin sections for further ultrastructural analysis. The technique was tested and refined in sections of the intestine containing numerous dividing cells and, once optimized, was then applied to identify the ultrastructure of slowly proliferating putative stem cells in the adult mouse spinal cord.
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Affiliation(s)
- S Momma
- Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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41
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Gustafsson JS, Birinyi A, Crum J, Ellisman M, Brodin L, Shupliakov O. Ultrastructural organization of lamprey reticulospinal synapses in three dimensions. J Comp Neurol 2002; 450:167-82. [PMID: 12124761 DOI: 10.1002/cne.10310] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The giant reticulospinal synapse in lamprey provides a unique model to study synaptic vesicle traffic. The axon permits microinjections, and the active zones are often separated from each other, which makes it possible to track vesicle cycling at individual release sites. However, the proportion of reticulospinal synapses with individual active zones ("simple synapses") is unknown and a quantitative description of their organization is lacking. Here, we report such data obtained by serial section analysis, intermediate-voltage electron microscopy, and electron tomography. The simple synapse was the most common type (78%). It consisted of one active zone contacting one dendritic process. The remaining synapses were "complex," mostly containing one vesicle cluster and two to three active zones synapsing with distinct dendritic shafts. Occasional axosomatic synapses with multiple active zones forming synapses with the same cell were also observed. The vast majority of active zones in all synapse types contained both chemical and electrotonic synaptic specializations. Quantitative analysis of simple synapses showed that the majority had active zones with a diameter of 0.8-1.8 microm. The number of synaptic vesicles and the height of the vesicle cluster in middle sections of serially cut synapses correlated with the active zone length within, but not above, this size range. Electron tomography of simple synapses revealed small filaments between the clustered synaptic vesicles. A single vesicle could be in contact with up to 12 filaments. Another type of filament, also associated with synaptic vesicles, emerged from dense projections. Up to six filaments could be traced from one dense projection.
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Affiliation(s)
- Jenny S Gustafsson
- Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
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42
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Arvidsson U, Risling M, Cullheim S, Dagerlind A, Lindå H, Shupliakov O, Ulfhake B, Hökfelt T. On the Distribution of GAP-43 and its Relation to Serotonin in Adult Monkey and Cat Spinal Cord and Lower Brainstem. Eur J Neurosci 2002; 4:777-784. [PMID: 12106322 DOI: 10.1111/j.1460-9568.1992.tb00187.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
By use of a monoclonal antibody, the distribution of growth-associated protein (GAP)-43-like immunoreactivity (LI) has been studied in the spinal cord of adult grey monkeys (Macaca fascicularis) and adult cats by use of immunofluorescence and peroxidase - antiperoxidase techniques. The brainstem was also studied with in situ hybridization histochemistry. In both monkeys and cats, a dense innervation of GAP-43-immunoreactive (IR) fibres was seen in close apposition to large cell bodies and their processes in the motor nucleus of the ventral horn. Double-labelling experiments revealed a high degree of coexistence between GAP-43- and 5-hydroxytryptamine (5-HT, serotonin)-LI in the monkey motor nucleus, while in the cat no such colocalization could be verified. At the electron microscopic level, GAP-43 labelling was seen as a coating of vesicles and axolemma inside the terminals. In both monkey and cat, cell bodies expressing mRNA encoding GAP-43 were demonstrated in the medullary midline raphe nuclei. A similar location was also encountered for mRNA for aromatic l-amino acid decarboxylase, an enzyme found in both catecholamine- and serotonin-containing neurons. The present results suggest that GAP-43 is present in the 5-HT bulbospinal pathway of the monkey. In the cat, GAP-43 mRNA-expressing cell bodies were demonstrated in areas where descending 5-HT neurons are located, but no convincing colocalization of 5-HT- and GAP-43-LI was found at spinal cord levels, despite the existence of extensive fibre networks containing either of the two compounds. Possible explanations for this species discrepancy are discussed. The function of GAP-43 in nerve terminals impinging on the motoneurons is unknown. However, it may play a role in transmitter release and/or plasticity, since such roles have been proposed for this protein in other systems.
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43
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Cans AS, Höök F, Shupliakov O, Ewing AG, Eriksson PS, Brodin L, Orwar O. Measurement of the dynamics of exocytosis and vesicle retrieval at cell populations using a quartz crystal microbalance. Anal Chem 2001; 73:5805-11. [PMID: 11791548 DOI: 10.1021/ac010777q] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The quartz crystal microbalance-dissipation technique (QCM-D) is used in two different measurement strategies to monitor the mass change and rigidity of populations of excitable cells during exocytosis and subsequent retrieval of dense-core vesicles. Two cell lines, NG 108-15 and PC 12, were grown to confluence on piezoelectric quartz crystals and were examined separately to demonstrate differences in release and retrieval with cells of different morphology, size, and number of dense-core vesicles. Stimulating the cells to exocytosis with media containing an elevated potassium concentration resulted in an increase in the frequency response corresponding to loss of mass from the cells owing to release of vesicles. In Ca2+-free media, the response was completely abolished. The amplitude and peak area in the frequency response corresponding to mass change with stimulated release was larger for PC 12 cells than for NG 108-15 cells, whereas the initial rate constants for the frequency responses were similar. The data suggest (1) that a greater number and larger size of vesicles in PC 12 cells results in a greater amount of release from these cells vs NG 108-15 cells, (2) the recycling of vesicles utilizes similar fusion/retrieval mechanisms in both cell types, (3) that the control of excess retrieval might be related to the number and size of released vesicles, and (4) that measured retrieval has a rapid onset, masking exocytosis and implying a rapid retrieval mechanism in the early stages of release. These results demonstrate that measurements of complex dynamic processes relating to dense-core vesicle release and retrieval can be simultaneously accomplished using the QCM-D technique.
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Affiliation(s)
- A S Cans
- Department of Chemistry, Göteborg University, Sweden
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44
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Abstract
The presence of zinc in synaptic terminals in the lamprey spinal cord was examined utilizing a modification of the Timm's sulfide silver method and with the fluorescent marker 6-methoxy-8-quinolyl-p-toluenesulfonamide (TSQ). Axons labeled with a Timm's staining method were predominantly located in the lateral region of the dorsal column. This correlated with a maximum of TSQ fluorescence in this region of the spinal cord. Single labeled terminals accumulating Timm reaction product were also found throughout the gray matter and fiber tracts. At the ultrastructural level, zinc was located in a population of synaptic terminals that co-localized gamma-aminobutyric acid (GABA) and glycine. Possible effects of Zn2+ on neuronal activity were examined. In spinobulbar interneurons, which receive GABAergic input in the dorsal column, zinc potentiated responses to GABA application, but it did not affect responses to GABA in motoneurons. Responses in motoneurons to pressure application of glycine were also not affected by Zn2+. Zinc, however, potentiated monosynaptic glycinergic inhibitory postsynaptic potentials (IPSPs) evoked in motoneurons by inhibitory locomotor network interneurons and increased frequency, but not amplitude of spontaneous miniature IPSPs recorded in the presence of tetrodotoxin (TTX), suggesting presynaptic effects. Glutamate responses and the amplitude of monosynaptic excitatory postsynaptic potentials (EPSPs) in motoneurons were reduced by zinc. These effects appeared to be mediated largely postsynaptically through an effect on the N-methyl-D-aspartate (NMDA) component of the glutamatergic input. Our results thus show that free zinc is present in inhibitory synaptic terminals in the lamprey spinal cord, and that it may function as a modulator of inhibitory synaptic transmission.
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Affiliation(s)
- A Birinyi
- Department of Anatomy, Histology, and Embryology, University Medical School of Debrecen, H-4012, Debrecen, Hungary
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45
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Lindå H, Shupliakov O, Örnung G, Ottersen OP, Storm‐Mathisen J, Risling M, Cullheim S. Ultrastructural evidence for a preferential elimination of glutamate‐immunoreactive synaptic terminals from spinal motoneurons after intramedullary axotomy. J Comp Neurol 2000. [DOI: 10.1002/1096-9861(20000911)425:1<10::aid-cne2>3.0.co;2-#] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Hans Lindå
- Department of Neuroscience, Karolinska Institutet, S‐171 77 Stockholm, Sweden
| | - Oleg Shupliakov
- Department of Neuroscience, Karolinska Institutet, S‐171 77 Stockholm, Sweden
| | - Göran Örnung
- Department of Neuroscience, Karolinska Institutet, S‐171 77 Stockholm, Sweden
| | | | | | - Mårten Risling
- Department of Neuroscience, Karolinska Institutet, S‐171 77 Stockholm, Sweden
| | - Staffan Cullheim
- Department of Neuroscience, Karolinska Institutet, S‐171 77 Stockholm, Sweden
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46
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Lindå H, Shupliakov O, Ornung G, Ottersen OP, Storm-Mathisen J, Risling M, Cullheim S. Ultrastructural evidence for a preferential elimination of glutamate-immunoreactive synaptic terminals from spinal motoneurons after intramedullary axotomy. J Comp Neurol 2000; 425:10-23. [PMID: 10940938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
After axotomy in the ventral funiculus of the cat spinal cord, about half of the population of lesioned motoneurons die at 1-3 weeks postoperatively, whereas the other half survives and generates new axons through the lesion area. To identify conditions that may promote survival and regeneration of motoneurons subjected to this kind of injury, the authors examined ultrastructurally lesion-induced changes in the number and distribution of nerve terminals on the somata and proximal dendrites of alpha-motoneurons in the 7th lumbar spinal segment (L7) of the cat spinal cord. Intramedullary axotomy resulted in a profound reduction in the number of nerve terminals impinging on the somata and proximal dendrites, with the maximal effect seen at 3 weeks postlesion. At that time, only 12-25% of the normal number of terminals remained on the cell somata, and 22-33% remained on proximal dendrites. Thereafter, a gradual increase in terminal numbers occurred, reaching normal levels at 34 weeks after the lesion. Already at 2 days postoperatively and, most obviously, at 3 weeks postoperatively, type S nerve terminals were eliminated to a larger degree than type F terminals. Postembedding immunohistochemistry confirmed that the largest reduction at 3 weeks was seen for excitatory glutamate-immunopositive type S nerve terminals (90%), whereas inhibitory glycine-immunoreactive and gamma-aminobutyric acid (GABA)-immunoreactive type F terminals were affected less (70% reduction). This led to a distinct shift in the ratio between the numbers of terminals that were immunopositive for glycine and GABA and the numbers of terminals that were labeled for glutamate. For the cell body, this ratio increased from 3.7 in normal material to 14.5 in lesioned motoneurons, whereas the corresponding values for proximal dendrites were 3.8 and 7.5. The preferential elimination of glutamatergic inputs to lesioned motoneurons may reflect an active reorganization of the synaptic input to diminish the excitotoxic influence on these neurons, thereby promoting the survival of motoneurons after intramedullary axotomy.
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Affiliation(s)
- H Lindå
- Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
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Shayan AJ, Brodin L, Ottersen OP, Birinyi A, Hill CE, Govind CK, Atwood HL, Shupliakov O. Neurotransmitter levels and synaptic strength at the Drosophila larval neuromuscular junction are not altered by mutation in the sluggish-A gene, which encodes proline oxidase and affects adult locomotion. J Neurogenet 2000; 14:165-92. [PMID: 10992167 DOI: 10.3109/01677060009083481] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The sluggish-A (slgA) gene of Drosophila melanogaster has been shown to encode for the enzyme proline oxidase, a mitochondrial enzyme which catalyzes the first step in the conversion of L-proline to L-glutamate. The slgA transcript is expressed in both larval and adult Drosophila melanogaster. Mutations in this gene lead to reduced proline oxidase activity and an elevation of free proline levels. Adult mutant flies show a striking reduction of motor activity. Since proline oxidase may contribute to the supply of the neurotransmitter glutamate in the nervous system, a reduction in proline oxidase activity could reduce neural glutamate pools and affect synaptic transmission in neurons utilizing glutamate as a transmitter, including peripheral motor neurons. We tested the hypothesis that glutamate, and synaptic transmission mediated by glutamate, are reduced at synapses of glutamatergic motor neurons in slgA mutants. Levels of glutamate and proline in different cell compartments, and functional properties of synaptic transmission were compared in slgA and control specimens. Proline is elevated in muscle cells of slgA mutants, indicating that the slgA gene regulates tissue proline levels. In nerve terminal varicosities, proline levels were low in both mutants and controls. Glutamate levels in nerve terminal varicosities of slgA mutants and controls were similar. In addition, we found that glutamatergic synaptic transmission at individual nerve endings and at the whole-cell level was similar in slgA mutants and controls. Thus, proline oxidase does not play a major role in generating neuronal glutamate pools at the Drosophila larval neuromuscular junction, and larval neuromuscular performance is not altered significantly in slgA mutants. Metabolic pathways other than that involving proline oxidase are able to sustain glutamatergic synaptic function in Drosophila larvae.
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Affiliation(s)
- A J Shayan
- Department of Physiology, Faculty of Medicine, Medical Science Building, University of Toronto, 1, King's College Circle, Toronto, ON, Canada M5S 1A8
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Gad H, Ringstad N, Löw P, Kjaerulff O, Gustafsson J, Wenk M, Di Paolo G, Nemoto Y, Crun J, Ellisman MH, De Camilli P, Shupliakov O, Brodin L. Fission and uncoating of synaptic clathrin-coated vesicles are perturbed by disruption of interactions with the SH3 domain of endophilin. Neuron 2000; 27:301-12. [PMID: 10985350 DOI: 10.1016/s0896-6273(00)00038-6] [Citation(s) in RCA: 235] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Coordination between sequential steps in synaptic vesicle endocytosis, including clathrin coat formation, fission, and uncoating, appears to involve proteinprotein interactions. Here, we show that compounds that disrupt interactions of the SH3 domain of endophilin with dynamin and synaptojanin impair synaptic vesicle endocytosis in a living synapse. Two distinct endocytic intermediates accumulated. Free clathrin-coated vesicles were induced by a peptide-blocking endophilin's SH3 domain and by antibodies to the proline-rich domain (PRD) of synaptojanin. Invaginated clathrin-coated pits were induced by the same peptide and by the SH3 domain of endophilin. We suggest that the SH3 domain of endophilin participates in both fission and uncoating and that it may be a key component of a molecular switch that couples the fission reaction to uncoating.
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Affiliation(s)
- H Gad
- The Nobel Institute for Neurophysiology, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Abstract
Synaptic vesicles are recycled with remarkable speed and precision in nerve terminals. A major recycling pathway involves clathrin-mediated endocytosis at endocytic zones located around sites of release. Different 'accessory' proteins linked to this pathway have been shown to alter the shape and composition of lipid membranes, to modify membrane-coat protein interactions, and to influence actin polymerization. These include the GTPase dynamin, the lysophosphatidic acid acyl transferase endophilin, and the phosphoinositide phosphatase synaptojanin. Protein perturbation studies in living nerve terminals are now beginning to link the actions of these proteins with morphologically defined steps of endocytosis.
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Affiliation(s)
- L Brodin
- Department of Neuroscience, The Nobel Institute for Neurophysiology, Karolinska Institutet, Stockholm, S-171 77, Sweden.
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Löw P, Norlin T, Risinger C, Larhammar D, Pieribone VA, Shupliakov O, Brodin L. Inhibition of neurotransmitter release in the lamprey reticulospinal synapse by antibody-mediated disruption of SNAP-25 function. Eur J Cell Biol 1999; 78:787-93. [PMID: 10604655 DOI: 10.1016/s0171-9335(99)80029-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Exocytosis - syntaxin - synaptobrevin - SNARE synaptic vesicle The lamprey giant reticulospinal synapse can be used to manipulate the molecular machinery of synaptic vesicle exocytosis by presynaptic microinjection. Here we test the effect of disrupting the function of the SNARE protein SNAP-25. Polyclonal SNAP-25 antibodies were shown in an in vitro assay to inhibit the binding between syntaxin and SNAP-25. When microinjected presynaptically, these antibodies produced a potent inhibition of the synaptic response. Ba2+ spikes recorded in the presynaptic axon were not altered, indicating that the effect was not due to a reduced presynaptic Ca2+ entry. Electron microscopic analysis showed that synaptic vesicle clusters had a similar organization in synapses of antibody-injected axons as in control axons, and the number of synaptic vesicles in apparent contact with the presynaptic plasma membrane was also similar. Clathrin-coated pits, which normally occur at the plasma membrane around stimulated synapses, were not detected after injection of SNAP-25 antibodies, consistent with a blockade of vesicle cycling. Thus, SNAP-25 antibodies, which disrupt the interaction with syntaxin, inhibit neurotransmitter release without affecting the number of synaptic vesicles at the plasma membrane. These results provide further support to the view that the formation of SNARE complexes is critical for membrane fusion, but not for the targeting of synaptic vesicles to the presynaptic membrane.
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Affiliation(s)
- P Löw
- The Nobel Institute for Neurophysiology, Department of Neuroscience, Karolinska Institutet, Stockholm/Sweden.
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