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Krohn J, Domart F, Do TT, Dresbach T. The synaptic vesicle protein Mover/TPRG1L is associated with lipid droplets in astrocytes. Glia 2023; 71:2799-2814. [PMID: 37539560 DOI: 10.1002/glia.24452] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 07/06/2023] [Accepted: 07/24/2023] [Indexed: 08/05/2023]
Abstract
Crucial brain functions such as neurotransmission, myelination, and signaling pose a high demand for lipids. Lipid dysregulation is associated with neuroinflammation and neurodegeneration. Astrocytes protect neurons from lipid induced damage by accumulating and metabolizing toxic lipids in organelles called lipid droplets (LDs). LDs have long been considered as lipid storage compartments in adipocytes, but less is known about their biogenesis and composition in the brain. In particular, proteins covering the LD surface are not yet fully identified. Here, we report that the presynaptic protein Mover/TPRG1L, which regulates the probability of neurotransmitter release in neurons, is a component of the LD coat in astrocytes. Using conventional and super-resolution microscopy, we demonstrate that Mover surrounds naive and oleic acid induced astrocytic LDs. We confirm the identity of astrocytic LDs using the neutral lipid stains Bodipy and LipidTox, as well as immunofluorescence for perilipin-2, a known component of the LD coat. In astrocytes, recombinant Mover was sufficient to induce an accumulation of LDs. Furthermore, we identified point mutations that abolish targeting to LDs and show similarities in the required binding sequences for association to the presynapse and LDs. Our results show that Mover is not only a presynaptic protein but also a candidate for LD regulation. This highlights the dual role of Mover in synaptic transmission and regulation of astrocytic LDs, which may be particularly important in the context of lipid-related neurological disorders.
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Affiliation(s)
- Jeremy Krohn
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Georg-August University of Göttingen, Göttingen, Germany
| | - Florelle Domart
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Georg-August University of Göttingen, Göttingen, Germany
| | - Thanh Thao Do
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Georg-August University of Göttingen, Göttingen, Germany
| | - Thomas Dresbach
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Georg-August University of Göttingen, Göttingen, Germany
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2
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Wittenmayer N, Petkova-Tuffy A, Borgmeyer M, Lee C, Becker J, Böning A, Kügler S, Rhee J, Viotti JS, Dresbach T. S-SCAM is essential for synapse formation. Front Cell Neurosci 2023; 17:1182493. [PMID: 38045729 PMCID: PMC10690602 DOI: 10.3389/fncel.2023.1182493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 10/02/2023] [Indexed: 12/05/2023] Open
Abstract
Synapse formation is critical for the wiring of neural circuits in the developing brain. The synaptic scaffolding protein S-SCAM/MAGI-2 has important roles in the assembly of signaling complexes at post-synaptic densities. However, the role of S-SCAM in establishing the entire synapse is not known. Here, we report significant effects of RNAi-induced S-SCAM knockdown on the number of synapses in early stages of network development in vitro. In vivo knockdown during the first three postnatal weeks reduced the number of dendritic spines in the rat brain neocortex. Knockdown of S-SCAM in cultured hippocampal neurons severely reduced the clustering of both pre- and post-synaptic components. This included synaptic vesicle proteins, pre- and post-synaptic scaffolding proteins, and cell adhesion molecules, suggesting that entire synapses fail to form. Correspondingly, functional and morphological characteristics of developing neurons were affected by reducing S-SCAM protein levels; neurons displayed severely impaired synaptic transmission and reduced dendritic arborization. A next-generation sequencing approach showed normal expression of housekeeping genes but changes in expression levels in 39 synaptic signaling molecules in cultured neurons. These results indicate that S-SCAM mediates the recruitment of all key classes of synaptic molecules during synapse assembly and is critical for the development of neural circuits in the developing brain.
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Affiliation(s)
- Nina Wittenmayer
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Göttingen, Germany
- Institute for Translational Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Andonia Petkova-Tuffy
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Göttingen, Germany
| | - Maximilian Borgmeyer
- Institute for Translational Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Chungku Lee
- Department of Molecular Neurobiology, Synaptic Physiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Jürgen Becker
- Institute of Anatomy and Cell Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Andreas Böning
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Göttingen, Germany
| | - Sebastian Kügler
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
| | - JeongSeop Rhee
- Department of Molecular Neurobiology, Synaptic Physiology Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Julio S. Viotti
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Göttingen, Germany
- University of Bordeaux, CNRS, IINS, UMR 5297, Bordeaux, France
| | - Thomas Dresbach
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Göttingen, Germany
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3
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Kuhse J, Groeneweg F, Kins S, Gorgas K, Nawrotzki R, Kirsch J, Kiss E. Loss of Extrasynaptic Inhibitory Glycine Receptors in the Hippocampus of an AD Mouse Model Is Restored by Treatment with Artesunate. Int J Mol Sci 2023; 24:ijms24054623. [PMID: 36902054 PMCID: PMC10002537 DOI: 10.3390/ijms24054623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/14/2023] [Accepted: 02/22/2023] [Indexed: 03/06/2023] Open
Abstract
Alzheimer's disease (AD) is characterized by synaptic failure and neuronal loss. Recently, we demonstrated that artemisinins restored the levels of key proteins of inhibitory GABAergic synapses in the hippocampus of APP/PS1 mice, a model of cerebral amyloidosis. In the present study, we analyzed the protein levels and subcellular localization of α2 and α3 subunits of GlyRs, indicated as the most abundant receptor subtypes in the mature hippocampus, in early and late stages of AD pathogenesis, and upon treatment with two different doses of artesunate (ARS). Immunofluorescence microscopy and Western blot analysis demonstrated that the protein levels of both α2 and α3 GlyRs are considerably reduced in the CA1 and the dentate gyrus of 12-month-old APP/PS1 mice when compared to WT mice. Notably, treatment with low-dose ARS affected GlyR expression in a subunit-specific way; the protein levels of α3 GlyR subunits were rescued to about WT levels, whereas that of α2 GlyRs were not affected significantly. Moreover, double labeling with a presynaptic marker indicated that the changes in GlyR α3 expression levels primarily involve extracellular GlyRs. Correspondingly, low concentrations of artesunate (≤1 µM) also increased the extrasynaptic GlyR cluster density in hAPPswe-transfected primary hippocampal neurons, whereas the number of GlyR clusters overlapping presynaptic VIAAT immunoreactivities remained unchanged. Thus, here we provide evidence that the protein levels and subcellular localization of α2 and α3 subunits of GlyRs show regional and temporal alterations in the hippocampus of APP/PS1 mice that can be modulated by the application of artesunate.
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Affiliation(s)
- Jochen Kuhse
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
| | - Femke Groeneweg
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
- Institute of Neuroanatomy, Medical Faculty Mannheim, University Heidelberg, 68167 Mannheim, Germany
| | - Stefan Kins
- Department of Human Biology and Human Genetics, University of Kaiserslautern-Landau, 67663 Kaiserslautern, Germany
| | - Karin Gorgas
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
| | - Ralph Nawrotzki
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
| | - Joachim Kirsch
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
| | - Eva Kiss
- Institute of Anatomy and Cell Biology, University of Heidelberg, 69117 Heidelberg, Germany
- Department of Cellular and Molecular Biology, George Emil Palade University of Medicine, Pharmacy, Science and Technology of Târgu Mureș, 540142 Târgu Mures, Romania
- Correspondence:
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4
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Ghelani T, Montenegro-Venegas C, Fejtova A, Dresbach T. Nanoscopical Analysis Reveals an Orderly Arrangement of the Presynaptic Scaffold Protein Bassoon at the Golgi-Apparatus. Front Mol Neurosci 2021; 14:744034. [PMID: 34867184 PMCID: PMC8632625 DOI: 10.3389/fnmol.2021.744034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/22/2021] [Indexed: 11/18/2022] Open
Abstract
Bassoon is a core scaffold protein of the presynaptic active zone. In brain synapses, the C-terminus of Bassoon is oriented toward the plasma membrane and its N-terminus is oriented toward synaptic vesicles. At the Golgi-apparatus, Bassoon is thought to assemble active zone precursor structures, but whether it is arranged in an orderly fashion is unknown. Understanding the topology of this large scaffold protein is important for models of active zone biogenesis. Using stimulated emission depletion nanoscopy in cultured hippocampal neurons, we found that an N-terminal intramolecular tag of recombinant Bassoon, but not C-terminal tag, colocalized with markers of the trans-Golgi network (TGN). The N-terminus of Bassoon was located between 48 and 69 nm away from TGN38, while its C-terminus was located between 100 and 115 nm away from TGN38. Sequences within the first 95 amino acids of Bassoon were required for this arrangement. Our results indicate that, at the Golgi-apparatus, Bassoon is oriented with its N-terminus toward and its C-terminus away from the trans Golgi network membrane. Moreover, they suggest that Bassoon is an extended molecule at the trans Golgi network with the distance between amino acids 97 and 3,938, estimated to be between 46 and 52 nm. Our data are consistent with a model, in which the N-terminus of Bassoon binds to the membranes of the trans-Golgi network, while the C-terminus associates with active zone components, thus reflecting the topographic arrangement characteristic of synapses also at the Golgi-apparatus.
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Affiliation(s)
- Tina Ghelani
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Göttingen, Germany
| | - Carolina Montenegro-Venegas
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Magdeburg, Germany.,Institute for Pharmacology and Toxicology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Anna Fejtova
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany.,Department of Psychiatry and Psychotherapy, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.,RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Thomas Dresbach
- Institute of Anatomy and Embryology, University Medical Center Göttingen, Göttingen, Germany
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5
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Petkova-Tuffy A, Gödecke N, Viotti J, Korte M, Dresbach T. Neuroligin-1 mediates presynaptic maturation through brain-derived neurotrophic factor signaling. BMC Biol 2021; 19:215. [PMID: 34579720 PMCID: PMC8474808 DOI: 10.1186/s12915-021-01145-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 09/01/2021] [Indexed: 12/15/2022] Open
Abstract
Background Maturation is a process that allows synapses to acquire full functionality, optimizing their activity to diverse neural circuits, and defects in synaptic maturation may contribute to neurodevelopmental disorders. Neuroligin-1 (NL1) is a postsynaptic cell adhesion molecule essential for synapse maturation, a role typically attributed to binding to pre-synaptic ligands, the neurexins. However, the pathways underlying the action of NL1 in synaptic maturation are incompletely understood, and some of its previously observed effects seem reminiscent of those described for the neurotrophin brain-derived neurotrophic factor (BDNF). Here, we show that maturational increases in active zone stability and synaptic vesicle recycling rely on the joint action of NL1 and brain-derived neurotrophic factor (BDNF). Results Applying BDNF to hippocampal neurons in primary cultures or organotypical slice cultures mimicked the effects of overexpressing NL1 on both structural and functional maturation. Overexpressing a NL1 mutant deficient in neurexin binding still induced presynaptic maturation. Like NL1, BDNF increased synaptic vesicle recycling and the augmentation of transmitter release by phorbol esters, both hallmarks of presynaptic maturation. Mimicking the effects of NL1, BDNF also increased the half-life of the active zone marker bassoon at synapses, reflecting increased active zone stability. Overexpressing NL1 increased the expression and synaptic accumulation of BDNF. Inhibiting BDNF signaling pharmacologically or genetically prevented the effects of NL1 on presynaptic maturation. Applying BDNF to NL1-knockout mouse cultures rescued defective presynaptic maturation, indicating that BDNF acts downstream of NL1 and can restore presynaptic maturation at late stages of network development. Conclusions Our data introduce BDNF as a novel and essential component in a transsynaptic pathway linking NL1-mediated cell adhesion, neurotrophin action, and presynaptic maturation. Our findings connect synaptic cell adhesion and neurotrophin signaling and may provide a therapeutic approach to neurodevelopmental disorders by targeting synapse maturation. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01145-7.
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Affiliation(s)
- Andonia Petkova-Tuffy
- Institute for Anatomy and Embryology, University Medical Center Göttingen, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Nina Gödecke
- Zoological Institute, Division of Cellular Neurobiology, TU Braunschweig, Spielmannstr. 7, 38106, Braunschweig, Germany
| | - Julio Viotti
- Institute for Anatomy and Embryology, University Medical Center Göttingen, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Martin Korte
- Zoological Institute, Division of Cellular Neurobiology, TU Braunschweig, Spielmannstr. 7, 38106, Braunschweig, Germany.,Helmholtz Centre for Infection Research, Research group Neuroinflammation and Neurodegeneration, Imhoffenstr. 7, 38104, Braunschweig, Germany
| | - Thomas Dresbach
- Institute for Anatomy and Embryology, University Medical Center Göttingen, Kreuzbergring 36, 37075, Göttingen, Germany.
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6
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Dakterzada F, David Benítez I, Targa A, Lladó A, Torres G, Romero L, de Gonzalo-Calvo D, Moncusí-Moix A, Tort-Merino A, Huerto R, Sánchez-de-la-Torre M, Barbé F, Piñol-Ripoll G. Reduced Levels of miR-342-5p in Plasma Are Associated With Worse Cognitive Evolution in Patients With Mild Alzheimer's Disease. Front Aging Neurosci 2021; 13:705989. [PMID: 34497505 PMCID: PMC8421031 DOI: 10.3389/fnagi.2021.705989] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/26/2021] [Indexed: 12/28/2022] Open
Abstract
Background Progressive cognitive decline is the most relevant clinical symptom of Alzheimer’s disease (AD). However, the rate of cognitive decline is highly variable between patients. Synaptic deficits are the neuropathological event most correlated with cognitive impairment in AD. Considering the important role of microRNAs (miRNAs) in regulating synaptic plasticity, our objective was to identify the plasma miRNAs associated with the rate of cognitive decline in patients with mild AD. Methods We analyzed 754 plasma miRNAs from 19 women diagnosed with mild AD using TaqMan low-density array cards. The patients were grouped based on the rate of decline in the MMSE score after 2 years [<4 points (N = 11) and ≥4 points (N = 8)]. The differentially expressed miRNAs between the two groups were validated in an independent cohort of men and women (N = 53) with mild AD using RT-qPCR. Results In the discovery cohort, 17 miRNAs were differentially expressed according to the fold change between patients with faster declines in cognition and those with slower declines. miR-342-5p demonstrated differential expression between the groups and a good correlation with the rate of cognitive decline in the validation cohort (r = −0.28; p = 0.026). This miRNA had a lower expression level in patients who suffered from more severe decline than in those who were cognitively more stable after 2 years (p = 0.049). Conclusion Lower levels of miR-342-5p in plasma were associated with faster cognitive decline in patients with mild AD after 2 years of follow-up.
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Affiliation(s)
- Farida Dakterzada
- Unitat Trastorns Cognitius, Clinical Neuroscience Research, Santa Maria University Hospital, IRBLleida, Lleida, Spain
| | - Iván David Benítez
- Translational Research in Respiratory Medicine, Hospital Universitari Arnau de Vilanova-Santa Maria, IRBLleida, Lleida, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Adriano Targa
- Translational Research in Respiratory Medicine, Hospital Universitari Arnau de Vilanova-Santa Maria, IRBLleida, Lleida, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Albert Lladó
- Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Department, Hospital Clínic, Institut D'Investigacion Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Gerard Torres
- Translational Research in Respiratory Medicine, Hospital Universitari Arnau de Vilanova-Santa Maria, IRBLleida, Lleida, Spain
| | - Leila Romero
- Unitat Trastorns Cognitius, Clinical Neuroscience Research, Santa Maria University Hospital, IRBLleida, Lleida, Spain
| | - David de Gonzalo-Calvo
- Translational Research in Respiratory Medicine, Hospital Universitari Arnau de Vilanova-Santa Maria, IRBLleida, Lleida, Spain
| | - Anna Moncusí-Moix
- Translational Research in Respiratory Medicine, Hospital Universitari Arnau de Vilanova-Santa Maria, IRBLleida, Lleida, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Adria Tort-Merino
- Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Department, Hospital Clínic, Institut D'Investigacion Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Raquel Huerto
- Unitat Trastorns Cognitius, Clinical Neuroscience Research, Santa Maria University Hospital, IRBLleida, Lleida, Spain
| | - Manuel Sánchez-de-la-Torre
- Translational Research in Respiratory Medicine, Hospital Universitari Arnau de Vilanova-Santa Maria, IRBLleida, Lleida, Spain.,Group of Precision Medicine in Chronic Diseases, Hospital Universitari Arnau de Vilanova-Santa Maria, IRBLleida, Lleida, Spain
| | - Ferran Barbé
- Translational Research in Respiratory Medicine, Hospital Universitari Arnau de Vilanova-Santa Maria, IRBLleida, Lleida, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Gerard Piñol-Ripoll
- Unitat Trastorns Cognitius, Clinical Neuroscience Research, Santa Maria University Hospital, IRBLleida, Lleida, Spain
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7
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Montenegro-Venegas C, Fienko S, Anni D, Pina-Fernández E, Frischknecht R, Fejtova A. Bassoon inhibits proteasome activity via interaction with PSMB4. Cell Mol Life Sci 2020; 78:1545-1563. [PMID: 32651614 PMCID: PMC7904567 DOI: 10.1007/s00018-020-03590-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 06/19/2020] [Accepted: 07/01/2020] [Indexed: 01/06/2023]
Abstract
Abstract Proteasomes are protein complexes that mediate controlled degradation of damaged or unneeded cellular proteins. In neurons, proteasome regulates synaptic function and its dysfunction has been linked to neurodegeneration and neuronal cell death. However, endogenous mechanisms controlling proteasomal activity are insufficiently understood. Here, we describe a novel interaction between presynaptic scaffolding protein bassoon and PSMB4, a β subunit of the 20S core proteasome. Expression of bassoon fragments that interact with PSMB4 in cell lines or in primary neurons attenuates all endopeptidase activities of cellular proteasome and induces accumulation of several classes of ubiquitinated and non-ubiquitinated substrates of the proteasome. Importantly, these effects are distinct from the previously reported impact of bassoon on ubiquitination and autophagy and might rely on a steric interference with the assembly of the 20S proteasome core. In line with a negative regulatory role of bassoon on endogenous proteasome we found increased proteasomal activity in the synaptic fractions prepared from brains of bassoon knock-out mice. Finally, increased activity of proteasome and lower expression levels of synaptic substrates of proteasome could be largely normalized upon expression of PSMB4-interacting fragments of bassoon in neurons derived from bassoon deficient mice. Collectively, we propose that bassoon interacts directly with proteasome to control its activity at presynapse and thereby it contributes to a compartment-specific regulation of neuronal protein homeostasis. These findings provide a mechanistic explanation for the recently described link of bassoon to human diseases associated with pathological protein aggregation. Graphic Abstract Presynaptic cytomatrix protein bassoon (Bsn) interacts with PSMB4, the β7 subunit of 20S core proteasome, via three independent interaction interfaces. Bsn inhibits proteasomal proteolytic activity and degradation of different classes of proteasomal substrates presumably due to steric interference with the assembly of 20S core of proteasome. Upon Bsn deletion in neurons, presynaptic substrates of the proteasome are depleted, which can be reversed upon expression of PSMB4-interacting interfaces of Bsn. Taken together, bsn controls the degree of proteasome degradation within the presynaptic compartment and thus, contributes to the regulation of synaptic proteome![]() Electronic supplementary material The online version of this article (10.1007/s00018-020-03590-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Carolina Montenegro-Venegas
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Institute for Pharmacology and Toxicology, Otto-von-Guericke University and Center for Behavior Brain Sciences (CBBS), Magdeburg, Germany
| | - Sandra Fienko
- Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
- RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UK Dementia Research Institute at UCL, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Daniela Anni
- Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Eneko Pina-Fernández
- RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Renato Frischknecht
- Department of Biology, Animal Physiology, Friedrich-Alexander University of Erlangen- Nürnberg, Erlangen, Germany
| | - Anna Fejtova
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany.
- Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Hospital, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany.
- RG Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany.
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8
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Hoffmann-Conaway S, Brockmann MM, Schneider K, Annamneedi A, Rahman KA, Bruns C, Textoris-Taube K, Trimbuch T, Smalla KH, Rosenmund C, Gundelfinger ED, Garner CC, Montenegro-Venegas C. Parkin contributes to synaptic vesicle autophagy in Bassoon-deficient mice. eLife 2020; 9:56590. [PMID: 32364493 PMCID: PMC7224700 DOI: 10.7554/elife.56590] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 05/02/2020] [Indexed: 12/18/2022] Open
Abstract
Mechanisms regulating the turnover of synaptic vesicle (SV) proteins are not well understood. They are thought to require poly-ubiquitination and degradation through proteasome, endo-lysosomal or autophagy-related pathways. Bassoon was shown to negatively regulate presynaptic autophagy in part by scaffolding Atg5. Here, we show that increased autophagy in Bassoon knockout neurons depends on poly-ubiquitination and that the loss of Bassoon leads to elevated levels of ubiquitinated synaptic proteins per se. Our data show that Bassoon knockout neurons have a smaller SV pool size and a higher turnover rate as indicated by a younger pool of SV2. The E3 ligase Parkin is required for increased autophagy in Bassoon-deficient neurons as the knockdown of Parkin normalized autophagy and SV protein levels and rescued impaired SV recycling. These data indicate that Bassoon is a key regulator of SV proteostasis and that Parkin is a key E3 ligase in the autophagy-mediated clearance of SV proteins.
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Affiliation(s)
| | - Marisa M Brockmann
- Charité - Universitätsmedizin Berlin, Institute of Neurobiology, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | | | - Anil Annamneedi
- Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.,Institute of Biology (IBIO), Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Kazi Atikur Rahman
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany
| | - Christine Bruns
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Kathrin Textoris-Taube
- Charité - Universitätsmedizin Berlin, Institute of Biochemistry, Core Facility High Throughput Mass Spectrometry, Berlin, Germany
| | - Thorsten Trimbuch
- Charité - Universitätsmedizin Berlin, Institute of Neurobiology, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Karl-Heinz Smalla
- Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Christian Rosenmund
- Charité - Universitätsmedizin Berlin, Institute of Neurobiology, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Eckart D Gundelfinger
- Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.,Molecular Neurobiology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Craig Curtis Garner
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institute of Neurobiology, Berlin, Germany.,NeuroCure Cluster of Excellence, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Carolina Montenegro-Venegas
- Leibniz Institute for Neurobiology, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.,Institute for Pharmacology and Toxicology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
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9
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Kiss E, Groeneweg F, Gorgas K, Schlicksupp A, Kins S, Kirsch J, Kuhse J. Amyloid-β Fosters p35/CDK5 Signaling Contributing to Changes of Inhibitory Synapses in Early Stages of Cerebral Amyloidosis. J Alzheimers Dis 2020; 74:1167-1187. [DOI: 10.3233/jad-190976] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Eva Kiss
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
- Department of Cellular and Molecular Biology, “Emil Palade” University of Medicine, Pharmacy, Science and Technology of Târgu Mureş, Târgu Mureş, Romania
| | - Femke Groeneweg
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Karin Gorgas
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Andrea Schlicksupp
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Stefan Kins
- Department of Human Biology and Human Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Joachim Kirsch
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Jochen Kuhse
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
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10
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Willems J, de Jong APH, Scheefhals N, Mertens E, Catsburg LAE, Poorthuis RB, de Winter F, Verhaagen J, Meye FJ, MacGillavry HD. ORANGE: A CRISPR/Cas9-based genome editing toolbox for epitope tagging of endogenous proteins in neurons. PLoS Biol 2020; 18:e3000665. [PMID: 32275651 PMCID: PMC7176289 DOI: 10.1371/journal.pbio.3000665] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 04/22/2020] [Accepted: 03/27/2020] [Indexed: 12/15/2022] Open
Abstract
The correct subcellular distribution of proteins establishes the complex morphology and function of neurons. Fluorescence microscopy techniques are invaluable to investigate subcellular protein distribution, but they suffer from the limited ability to efficiently and reliably label endogenous proteins with fluorescent probes. We developed ORANGE: Open Resource for the Application of Neuronal Genome Editing, which mediates targeted genomic integration of epitope tags in rodent dissociated neuronal culture, in organotypic slices, and in vivo. ORANGE includes a knock-in library for in-depth investigation of endogenous protein distribution, viral vectors, and a detailed two-step cloning protocol to develop knock-ins for novel targets. Using ORANGE with (live-cell) superresolution microscopy, we revealed the dynamic nanoscale organization of endogenous neurotransmitter receptors and synaptic scaffolding proteins, as well as previously uncharacterized proteins. Finally, we developed a mechanism to create multiple knock-ins in neurons, mediating multiplex imaging of endogenous proteins. Thus, ORANGE enables quantification of expression, distribution, and dynamics for virtually any protein in neurons at nanoscale resolution. This study describes the development of a genome editing toolbox (ORANGE) for endogenous tagging of proteins in neurons. This open resource allows the investigation of protein localization and dynamics in neurons using live-cell and super-resolution imaging techniques.
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Affiliation(s)
- Jelmer Willems
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Arthur P. H. de Jong
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Nicky Scheefhals
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Eline Mertens
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Lisa A. E. Catsburg
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Rogier B. Poorthuis
- Department of Translational Neuroscience, UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands
| | - Fred de Winter
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, the Netherlands
| | - Joost Verhaagen
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, the Netherlands
| | - Frank J. Meye
- Department of Translational Neuroscience, UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands
| | - Harold D. MacGillavry
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
- * E-mail:
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11
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Wang H, Li X, Xie X, Zhao H, Gao Y, Li Y, Xu X, Zhang X, Ke C, Liu J. Promotion of bone cancer pain development by decorin is accompanied by modification of excitatory synaptic molecules in the spinal cord. Mol Pain 2019; 15:1744806919864253. [PMID: 31258052 PMCID: PMC6659184 DOI: 10.1177/1744806919864253] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Bone cancer pain is refractory to currently available clinical treatment owing to
its complicated underlying mechanisms. Studies found that extracellular matrix
molecules can participate in the regulation of chronic pain. Decorin is one of
the most abundant extracellular matrix molecules, and the present study
evaluated the effect of decorin on the development of bone cancer pain. We found
that decorin was upregulated in the L4–L6 spinal dorsal horn of the bone cancer
pain rats. Spinal microinjection of a decorin-targeting RNAi lentivirus
alleviated bone cancer pain-induced mechanical allodynia and reduced the
expression of pGluR1-Ser831 in the bone cancer pain rats. Meanwhile, decorin
knockdown impaired the excitatory synaptogenesis in cultured neurons and
prevented the clustering and insertion of pGluR1-Ser831 into postsynaptic
membranes. Taken together, the results of our study suggested that decorin
contributes to the development of bone cancer pain possibly by regulating the
activity of excitatory synaptic molecules in the spinal cord. Our findings
provide a better understanding of the function of decorin as a possible
therapeutic target for alleviating bone cancer pain.
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Affiliation(s)
- Huan Wang
- 1 Department of Anesthesiology, Institute of Anesthesiology & Pain, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Xiaohui Li
- 1 Department of Anesthesiology, Institute of Anesthesiology & Pain, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Xianqiao Xie
- 1 Department of Anesthesiology, Institute of Anesthesiology & Pain, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Haiwen Zhao
- 1 Department of Anesthesiology, Institute of Anesthesiology & Pain, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Yan Gao
- 2 Department of PET Center, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Yang Li
- 1 Department of Anesthesiology, Institute of Anesthesiology & Pain, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Xueqin Xu
- 1 Department of Anesthesiology, Institute of Anesthesiology & Pain, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Xiaofei Zhang
- 1 Department of Anesthesiology, Institute of Anesthesiology & Pain, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Changbin Ke
- 1 Department of Anesthesiology, Institute of Anesthesiology & Pain, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Juying Liu
- 1 Department of Anesthesiology, Institute of Anesthesiology & Pain, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
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12
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Schattling B, Engler JB, Volkmann C, Rothammer N, Woo MS, Petersen M, Winkler I, Kaufmann M, Rosenkranz SC, Fejtova A, Thomas U, Bose A, Bauer S, Träger S, Miller KK, Brück W, Duncan KE, Salinas G, Soba P, Gundelfinger ED, Merkler D, Friese MA. Bassoon proteinopathy drives neurodegeneration in multiple sclerosis. Nat Neurosci 2019; 22:887-896. [PMID: 31011226 DOI: 10.1038/s41593-019-0385-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 03/13/2019] [Indexed: 12/21/2022]
Abstract
Multiple sclerosis (MS) is characterized by inflammatory insults that drive neuroaxonal injury. However, knowledge about neuron-intrinsic responses to inflammation is limited. By leveraging neuron-specific messenger RNA profiling, we found that neuroinflammation leads to induction and toxic accumulation of the synaptic protein bassoon (Bsn) in the neuronal somata of mice and patients with MS. Neuronal overexpression of Bsn in flies resulted in reduction of lifespan, while genetic disruption of Bsn protected mice from inflammation-induced neuroaxonal injury. Notably, pharmacological proteasome activation boosted the clearance of accumulated Bsn and enhanced neuronal survival. Our study demonstrates that neuroinflammation initiates toxic protein accumulation in neuronal somata and advocates proteasome activation as a potential remedy.
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Affiliation(s)
- Benjamin Schattling
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Jan Broder Engler
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Constantin Volkmann
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Nicola Rothammer
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Marcel S Woo
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Meike Petersen
- Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Iris Winkler
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Max Kaufmann
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Sina C Rosenkranz
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Anna Fejtova
- Leibniz-Institute für Neurobiologie, Magdeburg, Germany.,Psychiatrische und Psychotherapeutische Klinik, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Ulrich Thomas
- Leibniz-Institute für Neurobiologie, Magdeburg, Germany
| | - Aparajita Bose
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Simone Bauer
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Simone Träger
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Katharine K Miller
- Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Wolfgang Brück
- Institut für Neuropathologie, Universitätsmedizin Göttingen, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Kent E Duncan
- Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Gabriela Salinas
- Transkriptomanalyselabor, Institut für Entwicklungsbiochemie, Universitätsmedizin Göttingen, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Peter Soba
- Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Eckart D Gundelfinger
- Leibniz-Institute für Neurobiologie, Magdeburg, Germany.,Center for Behavioral Brain Sciences and Medical Faculty, Otto von Guericke Universität, Magdeburg, Germany
| | - Doron Merkler
- Department of Pathology and Immunology, Service of Clinical Pathology, Geneva Faculty of Medicine, Geneva, Switzerland
| | - Manuel A Friese
- Institut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
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13
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Riemann D, Petkova A, Dresbach T, Wallrafen R. An Optical Assay for Synaptic Vesicle Recycling in Cultured Neurons Overexpressing Presynaptic Proteins. J Vis Exp 2018:58043. [PMID: 30010661 PMCID: PMC6101998 DOI: 10.3791/58043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
At active presynaptic nerve terminals, synaptic vesicles undergo cycles of exo- and endocytosis. During recycling, the luminal domains of SV transmembrane proteins become exposed at the cell surface. One of these proteins is Synaptotagmin-1 (Syt1). An antibody directed against the luminal domain of Syt1, once added to the culture medium, is taken up during the exo-endocytotic cycle. This uptake is proportional to the amount of SV recycling and can be quantified through immunofluorescence. Here, we combine Syt1 antibody uptake with double transfection of cultured hippocampal neurons. This allows us to (1) localize presynaptic sites based on expression of recombinant presynaptic marker Synaptophysin, (2) determine their functionality using Syt1 uptake, and (3) characterize the targeting and effects of a protein of interest, GFP-Rogdi.
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Affiliation(s)
- Donatus Riemann
- Institute for Anatomy and Embryology, University Medical Centre Göttingen
| | - Andoniya Petkova
- Institute for Anatomy and Embryology, University Medical Centre Göttingen
| | - Thomas Dresbach
- Institute for Anatomy and Embryology, University Medical Centre Göttingen;
| | - Rebecca Wallrafen
- Institute for Anatomy and Embryology, University Medical Centre Göttingen
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14
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Riemann D, Wallrafen R, Dresbach T. The Kohlschütter-Tönz syndrome associated gene Rogdi encodes a novel presynaptic protein. Sci Rep 2017; 7:15791. [PMID: 29150638 PMCID: PMC5693994 DOI: 10.1038/s41598-017-16004-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 11/06/2017] [Indexed: 11/09/2022] Open
Abstract
Mutations in the human homolog of the Drosophila gene Rogdi cause Kohlschütter-Tönz syndrome. This disorder is characterised by amelogenesis imperfecta, as well as severe neurological symptoms including epilepsy and psychomotor delay. However, little is known about the protein encoded by Rogdi, and hence the pathogenic mechanisms underlying Kohlschütter-Tönz syndrome have remained elusive. Using immunofluorescence of rat cultured hippocampal neurons and brain sections we find that Rogdi is enriched at synaptic sites. In addition, recombinant GFP-Rogdi expressed in cultured neurons was efficiently targeted to presynaptic sites, where it colocalised with the presynaptic scaffolding protein Bassoon and the synaptic vesicle markers Synaptophysin, Synapsin-1, VAMP2/Synaptobrevin and Mover. Our data indicate that GFP-Rogdi harbours efficient signals for presynaptic targeting, and that Rogdi is a presynaptic protein. Thus, the neurological symptoms associated with Kohlschütter-Tönz syndrome may arise from presynaptic dysfunction.
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Affiliation(s)
- Donatus Riemann
- Institute for Anatomy and Embryology, University Medical Centre Göttingen, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Rebecca Wallrafen
- Institute for Anatomy and Embryology, University Medical Centre Göttingen, Kreuzbergring 36, 37075, Göttingen, Germany
| | - Thomas Dresbach
- Institute for Anatomy and Embryology, University Medical Centre Göttingen, Kreuzbergring 36, 37075, Göttingen, Germany.
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15
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Torres VI, Inestrosa NC. Vertebrate Presynaptic Active Zone Assembly: a Role Accomplished by Diverse Molecular and Cellular Mechanisms. Mol Neurobiol 2017; 55:4513-4528. [PMID: 28685386 DOI: 10.1007/s12035-017-0661-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/14/2017] [Indexed: 01/22/2023]
Abstract
Among all the biological systems in vertebrates, the central nervous system (CNS) is the most complex, and its function depends on specialized contacts among neurons called synapses. The assembly and organization of synapses must be exquisitely regulated for a normal brain function and network activity. There has been a tremendous effort in recent decades to understand the molecular and cellular mechanisms participating in the formation of new synapses and their organization, maintenance, and regulation. At the vertebrate presynapses, proteins such as Piccolo, Bassoon, RIM, RIM-BPs, CAST/ELKS, liprin-α, and Munc13 are constant residents and participate in multiple and dynamic interactions with other regulatory proteins, which define network activity and normal brain function. Here, we review the function of these active zone (AZ) proteins and diverse factors involved in AZ assembly and maintenance, with an emphasis on axonal trafficking of precursor vesicles, protein homo- and hetero-oligomeric interactions as a mechanism of AZ trapping and stabilization, and the role of F-actin in presynaptic assembly and its modulation by Wnt signaling.
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Affiliation(s)
- Viviana I Torres
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Nibaldo C Inestrosa
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile. .,Center for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, Australia. .,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.
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16
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Kawabe H, Mitkovski M, Kaeser PS, Hirrlinger J, Opazo F, Nestvogel D, Kalla S, Fejtova A, Verrier SE, Bungers SR, Cooper BH, Varoqueaux F, Wang Y, Nehring RB, Gundelfinger ED, Rosenmund C, Rizzoli SO, Südhof TC, Rhee JS, Brose N. ELKS1 localizes the synaptic vesicle priming protein bMunc13-2 to a specific subset of active zones. J Cell Biol 2017; 216:1143-1161. [PMID: 28264913 PMCID: PMC5379939 DOI: 10.1083/jcb.201606086] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 06/18/2016] [Accepted: 01/10/2017] [Indexed: 12/26/2022] Open
Abstract
Presynaptic active zones (AZs) are unique subcellular structures at neuronal synapses, which contain a network of specific proteins that control synaptic vesicle (SV) tethering, priming, and fusion. Munc13s are core AZ proteins with an essential function in SV priming. In hippocampal neurons, two different Munc13s-Munc13-1 and bMunc13-2-mediate opposite forms of presynaptic short-term plasticity and thus differentially affect neuronal network characteristics. We found that most presynapses of cortical and hippocampal neurons contain only Munc13-1, whereas ∼10% contain both Munc13-1 and bMunc13-2. Whereas the presynaptic recruitment and activation of Munc13-1 depends on Rab3-interacting proteins (RIMs), we demonstrate here that bMunc13-2 is recruited to synapses by the AZ protein ELKS1, but not ELKS2, and that this recruitment determines basal SV priming and short-term plasticity. Thus, synapse-specific interactions of different Munc13 isoforms with ELKS1 or RIMs are key determinants of the molecular and functional heterogeneity of presynaptic AZs.
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Affiliation(s)
- Hiroshi Kawabe
- Department of Molecular Neurobiology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Miso Mitkovski
- Light Microscopy Facility, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Pascal S Kaeser
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305.,Department of Neurobiology, Harvard Medical School, Boston, MA 02115
| | - Johannes Hirrlinger
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany.,Carl Ludwig Institute for Physiology, University of Leipzig, 04109 Leipzig, Germany
| | - Felipe Opazo
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, 37073 Göttingen, Germany.,Center for Biostructural Imaging of Neurodegeneration, University of Göttingen Medical Center, 37073 Göttingen, Germany
| | - Dennis Nestvogel
- Department of Molecular Neurobiology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Stefan Kalla
- Department of Molecular Neurobiology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Anna Fejtova
- Department of Neurochemistry and Molecular Biology, Leibniz Institute of Neurobiology, 39118 Magdeburg, Germany.,Research Group Presynaptic Plasticity, Leibniz Institute of Neurobiology and Center for Behavioral Brain Sciences, Otto von Guericke University, 39106 Magdeburg, Germany.,Department of Psychiatry and Psychotherapy, University Hospital, Friedrich Alexander University Erlangen-Nuremberg, 91054 Erlangen, Germany
| | - Sophie E Verrier
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Simon R Bungers
- Department of Molecular Neurobiology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Benjamin H Cooper
- Department of Molecular Neurobiology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Frederique Varoqueaux
- Department of Molecular Neurobiology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Yun Wang
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Ralf B Nehring
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030.,Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
| | - Eckart D Gundelfinger
- Department of Neurochemistry and Molecular Biology, Leibniz Institute of Neurobiology, 39118 Magdeburg, Germany
| | - Christian Rosenmund
- Neuroscience Research Centre and NeuroCure, Charité, University Medicine Berlin, 10117 Berlin, Germany
| | - Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University of Göttingen Medical Center, 37073 Göttingen, Germany
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Jeong-Seop Rhee
- Department of Molecular Neurobiology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
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17
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Okerlund ND, Schneider K, Leal-Ortiz S, Montenegro-Venegas C, Kim SA, Garner LC, Waites CL, Gundelfinger ED, Reimer RJ, Garner CC. Bassoon Controls Presynaptic Autophagy through Atg5. Neuron 2017; 93:897-913.e7. [DOI: 10.1016/j.neuron.2017.01.026] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 06/28/2016] [Accepted: 01/25/2017] [Indexed: 12/22/2022]
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18
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Terry-Lorenzo RT, Torres VI, Wagh D, Galaz J, Swanson SK, Florens L, Washburn MP, Waites CL, Gundelfinger ED, Reimer RJ, Garner CC. Trio, a Rho Family GEF, Interacts with the Presynaptic Active Zone Proteins Piccolo and Bassoon. PLoS One 2016; 11:e0167535. [PMID: 27907191 PMCID: PMC5132261 DOI: 10.1371/journal.pone.0167535] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/15/2016] [Indexed: 12/17/2022] Open
Abstract
Synaptic vesicles (SVs) fuse with the plasma membrane at a precise location called the presynaptic active zone (AZ). This fusion is coordinated by proteins embedded within a cytoskeletal matrix assembled at the AZ (CAZ). In the present study, we have identified a novel binding partner for the CAZ proteins Piccolo and Bassoon. This interacting protein, Trio, is a member of the Dbl family of guanine nucleotide exchange factors (GEFs) known to regulate the dynamic assembly of actin and growth factor dependent axon guidance and synaptic growth. Trio was found to interact with the C-terminal PBH 9/10 domains of Piccolo and Bassoon via its own N-terminal Spectrin repeats, a domain that is also critical for its localization to the CAZ. Moreover, our data suggest that regions within the C-terminus of Trio negatively regulate its interactions with Piccolo/Bassoon. These findings provide a mechanism for the presynaptic targeting of Trio and support a model in which Piccolo and Bassoon play a role in regulating neurotransmission through interactions with proteins, including Trio, that modulate the dynamic assembly of F-actin during cycles of synaptic vesicle exo- and endocytosis.
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Affiliation(s)
- Ryan T. Terry-Lorenzo
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
| | - Viviana I. Torres
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, Alameda, Santiago, Chile
| | - Dhananjay Wagh
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
| | - Jose Galaz
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
| | - Selene K. Swanson
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Laurence Florens
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Michael P. Washburn
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Clarissa L. Waites
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
| | - Eckart D. Gundelfinger
- Dept. of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Richard J. Reimer
- Dept. of Neurology and Neurological Sciences Stanford University and Veterans Affairs Palo Alto Health Care System, Palo Alto, California, United States of America
| | - Craig C. Garner
- Dept. of Psychiatry and Behavioral Science, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
- German Centers for Neurodegenerative Diseases, Charité - Medical University, Berlin, Germany
- * E-mail:
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19
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Bodaleo FJ, Gonzalez-Billault C. The Presynaptic Microtubule Cytoskeleton in Physiological and Pathological Conditions: Lessons from Drosophila Fragile X Syndrome and Hereditary Spastic Paraplegias. Front Mol Neurosci 2016; 9:60. [PMID: 27504085 PMCID: PMC4958632 DOI: 10.3389/fnmol.2016.00060] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 07/11/2016] [Indexed: 11/21/2022] Open
Abstract
The capacity of the nervous system to generate neuronal networks relies on the establishment and maintenance of synaptic contacts. Synapses are composed of functionally different presynaptic and postsynaptic compartments. An appropriate synaptic architecture is required to provide the structural basis that supports synaptic transmission, a process involving changes in cytoskeletal dynamics. Actin microfilaments are the main cytoskeletal components present at both presynaptic and postsynaptic terminals in glutamatergic synapses. However, in the last few years it has been demonstrated that microtubules (MTs) transiently invade dendritic spines, promoting their maturation. Nevertheless, the presence and functions of MTs at the presynaptic site are still a matter of debate. Early electron microscopy (EM) studies revealed that MTs are present in the presynaptic terminals of the central nervous system (CNS) where they interact with synaptic vesicles (SVs) and reach the active zone. These observations have been reproduced by several EM protocols; however, there is empirical heterogeneity in detecting presynaptic MTs, since they appear to be both labile and unstable. Moreover, increasing evidence derived from studies in the fruit fly neuromuscular junction proposes different roles for MTs in regulating presynaptic function in physiological and pathological conditions. In this review, we summarize the main findings that support the presence and roles of MTs at presynaptic terminals, integrating descriptive and biochemical analyses, and studies performed in invertebrate genetic models.
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Affiliation(s)
- Felipe J Bodaleo
- Laboratory of Cell and Neuronal Dynamics, Department of Biology, Faculty of Sciences, Universidad de ChileSantiago, Chile; Center for Geroscience, Brain Health and Metabolism (GERO)Santiago, Chile
| | - Christian Gonzalez-Billault
- Laboratory of Cell and Neuronal Dynamics, Department of Biology, Faculty of Sciences, Universidad de ChileSantiago, Chile; Center for Geroscience, Brain Health and Metabolism (GERO)Santiago, Chile; The Buck Institute for Research on Aging, NovatoCA, USA
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20
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Gundelfinger ED, Reissner C, Garner CC. Role of Bassoon and Piccolo in Assembly and Molecular Organization of the Active Zone. Front Synaptic Neurosci 2016; 7:19. [PMID: 26793095 PMCID: PMC4709825 DOI: 10.3389/fnsyn.2015.00019] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/14/2015] [Indexed: 01/05/2023] Open
Abstract
Bassoon and Piccolo are two very large scaffolding proteins of the cytomatrix assembled at the active zone (CAZ) where neurotransmitter is released. They share regions of high sequence similarity distributed along their entire length and seem to share both overlapping and distinct functions in organizing the CAZ. Here, we survey our present knowledge on protein-protein interactions and recent progress in understanding of molecular functions of these two giant proteins. These include roles in the assembly of active zones (AZ), the localization of voltage-gated Ca2+ channels (VGCCs) in the vicinity of release sites, synaptic vesicle (SV) priming and in the case of Piccolo, a role in the dynamic assembly of the actin cytoskeleton. Piccolo and Bassoon are also important for the maintenance of presynaptic structure and function, as well as for the assembly of CAZ specializations such as synaptic ribbons. Recent findings suggest that they are also involved in the regulation activity-dependent communication between presynaptic boutons and the neuronal nucleus. Together these observations suggest that Bassoon and Piccolo use their modular structure to organize super-molecular complexes essential for various aspects of presynaptic function.
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Affiliation(s)
- Eckart D Gundelfinger
- Department Neurochemistry and Molecular Biology, Leibniz Institute for NeurobiologyMagdeburg, Germany; Center for Behavioral Brain SciencesMagdeburg, Germany; Medical Faculty, Otto von Guericke UniversityMagdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE) Site MagdeburgMagdeburg, Germany
| | - Carsten Reissner
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms University Münster, Germany
| | - Craig C Garner
- German Center for Neurodegenerative Diseases (DZNE) Site BerlinBerlin, Germany; Charité Medical UniversityBerlin, Germany
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21
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Ivanova D, Dirks A, Montenegro-Venegas C, Schöne C, Altrock WD, Marini C, Frischknecht R, Schanze D, Zenker M, Gundelfinger ED, Fejtova A. Synaptic activity controls localization and function of CtBP1 via binding to Bassoon and Piccolo. EMBO J 2015; 34:1056-77. [PMID: 25652077 DOI: 10.15252/embj.201488796] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 01/08/2015] [Indexed: 11/09/2022] Open
Abstract
Persistent experience-driven adaptation of brain function is associated with alterations in gene expression patterns, resulting in structural and functional neuronal remodeling. How synaptic activity-in particular presynaptic performance-is coupled to gene expression in nucleus remains incompletely understood. Here, we report on a role of CtBP1, a transcriptional co-repressor enriched in presynapses and nuclei, in the activity-driven reconfiguration of gene expression in neurons. We demonstrate that presynaptic and nuclear pools of CtBP1 are interconnected and that both synaptic retention and shuttling of CtBP1 between cytoplasm and nucleus are co-regulated by neuronal activity. Finally, we show that CtBP1 is targeted and/or anchored to presynapses by direct interaction with the active zone scaffolding proteins Bassoon and Piccolo. This association is regulated by neuronal activity via modulation of cellular NAD/NADH levels and restrains the size of the CtBP1 pool available for nuclear import, thus contributing to the control of activity-dependent gene expression. Our combined results reveal a mechanism for coupling activity-induced molecular rearrangements in the presynapse with reconfiguration of neuronal gene expression.
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Affiliation(s)
- Daniela Ivanova
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Research Group Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Anika Dirks
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | | | - Cornelia Schöne
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Wilko D Altrock
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Center for Behavioral Brain Science, Otto von Guericke University, Magdeburg, Germany
| | - Claudia Marini
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Renato Frischknecht
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Center for Behavioral Brain Science, Otto von Guericke University, Magdeburg, Germany
| | - Denny Schanze
- Institute for Human Genetics, Otto von Guericke University, Magdeburg, Germany
| | - Martin Zenker
- Institute for Human Genetics, Otto von Guericke University, Magdeburg, Germany
| | - Eckart D Gundelfinger
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Center for Behavioral Brain Science, Otto von Guericke University, Magdeburg, Germany Molecular Neurobiology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
| | - Anna Fejtova
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany Research Group Presynaptic Plasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany Center for Behavioral Brain Science, Otto von Guericke University, Magdeburg, Germany
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22
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Ubiquitin E3 ligase Nedd4-1 acts as a downstream target of PI3K/PTEN-mTORC1 signaling to promote neurite growth. Proc Natl Acad Sci U S A 2014; 111:13205-10. [PMID: 25157163 DOI: 10.1073/pnas.1400737111] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Protein ubiquitination is a core regulatory determinant of neural development. Previous studies have indicated that the Nedd4-family E3 ubiquitin ligases Nedd4-1 and Nedd4-2 may ubiquitinate phosphatase and tensin homolog (PTEN) and thereby regulate axonal growth in neurons. Using conditional knockout mice, we show here that Nedd4-1 and Nedd4-2 are indeed required for axonal growth in murine central nervous system neurons. However, in contrast to previously published data, we demonstrate that PTEN is not a substrate of Nedd4-1 and Nedd4-2, and that aberrant PTEN ubiquitination is not involved in the impaired axon growth upon deletion of Nedd4-1 and Nedd4-2. Rather, PTEN limits Nedd4-1 protein levels by modulating the activity of mTORC1, a protein complex that controls protein synthesis and cell growth. Our data demonstrate that Nedd4-family E3 ligases promote axonal growth and branching in the developing mammalian brain, where PTEN is not a relevant substrate. Instead, PTEN controls neurite growth by regulating Nedd4-1 expression.
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23
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Kalbouneh H, Schlicksupp A, Kirsch J, Kuhse J. Cyclin-dependent kinase 5 is involved in the phosphorylation of gephyrin and clustering of GABAA receptors at inhibitory synapses of hippocampal neurons. PLoS One 2014; 9:e104256. [PMID: 25093719 PMCID: PMC4122414 DOI: 10.1371/journal.pone.0104256] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 07/10/2014] [Indexed: 11/19/2022] Open
Abstract
CDK5 has been implicated in neural functions including growth, neuronal migration, synaptic transmission and plasticity of excitatory chemical synapses. Here we report robust effects of CDK5 on phosphorylation of the postsynaptic scaffold protein gephyrin and clustering of inhibitory GABAA receptors in hippocampal neurons. shRNA-mediated knockdown of CDK5 and pharmacological inhibition of cyclin-dependent kinases reduced phosphorylated gephyrin clusters and postsynaptic γ2-containing GABAA receptors. Phosphorylation of S270 is antagonized by PP1/PP2a phosphatase and site-directed mutagenesis and in vitro phosphorylation experiments indicate that S270 is a putative CDK5 phosphorylation site of gephyrin. Our data suggest that CDK5 plays an essential role for the stability of gephyrin-dependent GABAA receptor clusters in hippocampal neurons.
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Affiliation(s)
- Heba Kalbouneh
- Department of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Andrea Schlicksupp
- Department of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Joachim Kirsch
- Department of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Jochen Kuhse
- Department of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
- * E-mail:
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24
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Davydova D, Marini C, King C, Klueva J, Bischof F, Romorini S, Montenegro-Venegas C, Heine M, Schneider R, Schröder MS, Altrock WD, Henneberger C, Rusakov DA, Gundelfinger ED, Fejtova A. Bassoon specifically controls presynaptic P/Q-type Ca(2+) channels via RIM-binding protein. Neuron 2014; 82:181-94. [PMID: 24698275 DOI: 10.1016/j.neuron.2014.02.012] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/28/2014] [Indexed: 12/11/2022]
Abstract
Voltage-dependent Ca(2+) channels (CaVs) represent the principal source of Ca(2+) ions that trigger evoked neurotransmitter release from presynaptic boutons. Ca(2+) influx is mediated mainly via CaV2.1 (P/Q-type) and CaV2.2 (N-type) channels, which differ in their properties. Their relative contribution to synaptic transmission changes during development and tunes neurotransmission during synaptic plasticity. The mechanism of differential recruitment of CaV2.1 and CaV2.2 to release sites is largely unknown. Here, we show that the presynaptic scaffolding protein Bassoon localizes specifically CaV2.1 to active zones via molecular interaction with the RIM-binding proteins (RBPs). A genetic deletion of Bassoon or an acute interference with Bassoon-RBP interaction reduces synaptic abundance of CaV2.1, weakens P/Q-type Ca(2+) current-driven synaptic transmission, and results in higher relative contribution of neurotransmission dependent on CaV2.2. These data establish Bassoon as a major regulator of the molecular composition of the presynaptic neurotransmitter release sites.
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Affiliation(s)
- Daria Davydova
- Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Claudia Marini
- Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Claire King
- Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Julia Klueva
- Molecular Physiology Group, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Ferdinand Bischof
- Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Stefano Romorini
- Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Carolina Montenegro-Venegas
- Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Martin Heine
- Molecular Physiology Group, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Romy Schneider
- Molecular Physiology Group, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Markus S Schröder
- Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Wilko D Altrock
- Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany; Center for Behavioral Brain Sciences and Medical Faculty, Otto von Guericke University, 39118 Magdeburg, Germany
| | - Christian Henneberger
- Institute of Neurology, University College London, London WC1N 3BG, UK; Institute of Cellular Neuroscience, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Dmitri A Rusakov
- Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Eckart D Gundelfinger
- Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany; Center for Behavioral Brain Sciences and Medical Faculty, Otto von Guericke University, 39118 Magdeburg, Germany.
| | - Anna Fejtova
- Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany; Presynaptic Plasticity Group, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany.
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25
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Bury LA, Sabo SL. Dynamic mechanisms of neuroligin-dependent presynaptic terminal assembly in living cortical neurons. Neural Dev 2014; 9:13. [PMID: 24885664 PMCID: PMC4049477 DOI: 10.1186/1749-8104-9-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 05/12/2014] [Indexed: 12/23/2022] Open
Abstract
Background Synapse formation occurs when synaptogenic signals trigger coordinated development of pre and postsynaptic structures. One of the best-characterized synaptogenic signals is trans-synaptic adhesion. However, it remains unclear how synaptic proteins are recruited to sites of adhesion. In particular, it is unknown whether synaptogenic signals attract synaptic vesicle (SV) and active zone (AZ) proteins to nascent synapses or instead predominantly function to create sites that are capable of forming synapses. It is also unclear how labile synaptic proteins are at developing synapses after their initial recruitment. To address these issues, we used long-term, live confocal imaging of presynaptic terminal formation in cultured cortical neurons after contact with the synaptogenic postsynaptic adhesion proteins neuroligin-1 or SynCAM-1. Results Surprisingly, we find that trans-synaptic adhesion does not attract SV or AZ proteins nor alter their transport. In addition, although neurexin (the presynaptic partner of neuroligin) typically accumulates over the entire region of contact between axons and neuroligin-1-expressing cells, SV proteins selectively assemble at spots of enhanced neurexin clustering. The arrival and maintenance of SV proteins at these sites is highly variable over the course of minutes to hours, and this variability correlates with neurexin levels at individual synapses. Conclusions Together, our data support a model of synaptogenesis where presynaptic proteins are trapped at specific axonal sites, where they are stabilized by trans-synaptic adhesion signaling.
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Affiliation(s)
| | - Shasta L Sabo
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
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26
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Photoconversion of CFP to study neuronal tissue with electron microscopy. Methods Mol Biol 2014. [PMID: 24718796 DOI: 10.1007/978-1-4939-0470-9_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Being able to use versatile light microscopy on live or fixed samples followed by electron microscopy imaging for high resolution analyses is a challenging goal. The advantage is of course that tracing and localizing fluorescently labeled molecules yields great information about dynamic cellular processes, while electron microscopy of the same sample provides exquisite information about subcellular structures. Here, I describe the straightforward combination of both methods by photoconversion of diaminobenzidine (DAB) through cyan fluorescent protein (CFP) tagged proteins localized to the Golgi apparatus in primary hippocampal neurons.
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27
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Nanguneri S, Flottmann B, Herrmannsdörfer F, Thomas K, Heilemann M. Single-molecule super-resolution imaging by tryptophan-quenching-induced photoswitching of phalloidin-fluorophore conjugates. Microsc Res Tech 2014; 77:510-6. [PMID: 24595992 DOI: 10.1002/jemt.22349] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 01/24/2014] [Accepted: 02/12/2014] [Indexed: 11/09/2022]
Abstract
Photophysical properties of any fluorophore are governed by the chemical nanoenvironment. In the context of imaging biological samples, this translates to different photophysical properties for different labels and probes. Here, we demonstrate that the nanoenvironment of fluorophores within a probe can be advantageously used to induce particular properties such as light-induced photoswitching. We demonstrate efficient photoswitching and single-molecule super-resolution imaging for various fluorophore-phalloidin conjugates in aqueous buffer without the addition of further chemicals. We further demonstrate the utility of two-color imaging of fluorophore-phalloidin and a photoactivatable fluorescent protein in presynaptic nerve terminals.
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Affiliation(s)
- Siddharth Nanguneri
- Institute of Anatomy and Cell Biology, Heidelberg University, INF 307, 69120, Heidelberg, Germany
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28
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Liu H, Bai H, Hui E, Yang L, Evans CS, Wang Z, Kwon SE, Chapman ER. Synaptotagmin 7 functions as a Ca2+-sensor for synaptic vesicle replenishment. eLife 2014; 3:e01524. [PMID: 24569478 PMCID: PMC3930910 DOI: 10.7554/elife.01524] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Synaptotagmin (syt) 7 is one of three syt isoforms found in all metazoans; it is ubiquitously expressed, yet its function in neurons remains obscure. Here, we resolved Ca(2+)-dependent and Ca(2+)-independent synaptic vesicle (SV) replenishment pathways, and found that syt 7 plays a selective and critical role in the Ca(2+)-dependent pathway. Mutations that disrupt Ca(2+)-binding to syt 7 abolish this function, suggesting that syt 7 functions as a Ca(2+)-sensor for replenishment. The Ca(2+)-binding protein calmodulin (CaM) has also been implicated in SV replenishment, and we found that loss of syt 7 was phenocopied by a CaM antagonist. Moreover, we discovered that syt 7 binds to CaM in a highly specific and Ca(2+)-dependent manner; this interaction requires intact Ca(2+)-binding sites within syt 7. Together, these data indicate that a complex of two conserved Ca(2+)-binding proteins, syt 7 and CaM, serve as a key regulator of SV replenishment in presynaptic nerve terminals. DOI: http://dx.doi.org/10.7554/eLife.01524.001.
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Affiliation(s)
- Huisheng Liu
- Department of Neuroscience, Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, United States
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29
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Mendoza Schulz A, Jing Z, Sánchez Caro JM, Wetzel F, Dresbach T, Strenzke N, Wichmann C, Moser T. Bassoon-disruption slows vesicle replenishment and induces homeostatic plasticity at a CNS synapse. EMBO J 2014; 33:512-27. [PMID: 24442636 DOI: 10.1002/embj.201385887] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Endbulb of Held terminals of auditory nerve fibers (ANF) transmit auditory information at hundreds per second to bushy cells (BCs) in the anteroventral cochlear nucleus (AVCN). Here, we studied the structure and function of endbulb synapses in mice that lack the presynaptic scaffold bassoon and exhibit reduced ANF input into the AVCN. Endbulb terminals and active zones were normal in number and vesicle complement. Postsynaptic densities, quantal size and vesicular release probability were increased while vesicle replenishment and the standing pool of readily releasable vesicles were reduced. These opposing effects canceled each other out for the first evoked EPSC, which showed unaltered amplitude. We propose that ANF activity deprivation drives homeostatic plasticity in the AVCN involving synaptic upscaling and increased intrinsic BC excitability. In vivo recordings from individual mutant BCs demonstrated a slightly improved response at sound onset compared to ANF, likely reflecting the combined effects of ANF convergence and homeostatic plasticity. Further, we conclude that bassoon promotes vesicular replenishment and, consequently, a large standing pool of readily releasable synaptic vesicles at the endbulb synapse.
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Affiliation(s)
- Alejandro Mendoza Schulz
- InnerEarLab, Department of Otolaryngology, University Medical Center Göttingen, Göttingen, Germany
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30
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Effects of two elongation factor 1A isoforms on the formation of gephyrin clusters at inhibitory synapses in hippocampal neurons. Histochem Cell Biol 2013; 140:603-9. [DOI: 10.1007/s00418-013-1122-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2013] [Indexed: 10/26/2022]
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31
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Ahmed S, Wittenmayer N, Kremer T, Hoeber J, Kiran Akula A, Urlaub H, Islinger M, Kirsch J, Dean C, Dresbach T. Mover is a homomeric phospho-protein present on synaptic vesicles. PLoS One 2013; 8:e63474. [PMID: 23723986 PMCID: PMC3665746 DOI: 10.1371/journal.pone.0063474] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Accepted: 04/03/2013] [Indexed: 01/13/2023] Open
Abstract
With remarkably few exceptions, the molecules mediating synaptic vesicle exocytosis at active zones are structurally and functionally conserved between vertebrates and invertebrates. Mover was found in a yeast-2-hybrid assay using the vertebrate-specific active zone scaffolding protein bassoon as a bait. Peptides of Mover have been reported in proteomics screens for self-interacting proteins, phosphorylated proteins, and synaptic vesicle proteins, respectively. Here, we tested the predictions arising from these screens. Using flotation assays, carbonate stripping of peripheral membrane proteins, mass spectrometry, immunogold labelling of purified synaptic vesicles, and immuno-organelle isolation, we found that Mover is indeed a peripheral synaptic vesicle membrane protein. In addition, by generating an antibody against phosphorylated Mover and Western blot analysis of fractionated rat brain, we found that Mover is a bona fide phospho-protein. The localization of Mover to synaptic vesicles is phosphorylation dependent; treatment with a phosphatase caused Mover to dissociate from synaptic vesicles. A yeast-2-hybrid screen, co-immunoprecipitation and cell-based optical assays of homomerization revealed that Mover undergoes homophilic interaction, and regions within both the N- and C- terminus of the protein are required for this interaction. Deleting a region required for homomeric interaction abolished presynaptic targeting of recombinant Mover in cultured neurons. Together, these data prove that Mover is associated with synaptic vesicles, and implicate phosphorylation and multimerization in targeting of Mover to synaptic vesicles and presynaptic sites.
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Affiliation(s)
- Saheeb Ahmed
- European Neuroscience Institute, Goettingen, Germany
| | - Nina Wittenmayer
- Center of Anatomy, University of Goettingen Medical School Goettingen, Germany
| | - Thomas Kremer
- Institute for Anatomy & Cell Biology, University of Heidelberg Medical School, Heidelberg, Germany
| | - Jan Hoeber
- Center of Anatomy, University of Goettingen Medical School Goettingen, Germany
| | - Asha Kiran Akula
- Center of Anatomy, University of Goettingen Medical School Goettingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - Markus Islinger
- Department of Neuroanatomy, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Joachim Kirsch
- Institute for Anatomy & Cell Biology, University of Heidelberg Medical School, Heidelberg, Germany
| | - Camin Dean
- European Neuroscience Institute, Goettingen, Germany
- * E-mail: (CD); (TD)
| | - Thomas Dresbach
- Center of Anatomy, University of Goettingen Medical School Goettingen, Germany
- * E-mail: (CD); (TD)
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32
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Disruption of the presynaptic cytomatrix protein bassoon degrades ribbon anchorage, multiquantal release, and sound encoding at the hair cell afferent synapse. J Neurosci 2013; 33:4456-67. [PMID: 23467361 DOI: 10.1523/jneurosci.3491-12.2013] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Inner hair cells (IHCs) of the cochlea use ribbon synapses to transmit auditory information faithfully to spiral ganglion neurons (SGNs). In the present study, we used genetic disruption of the presynaptic scaffold protein bassoon in mice to manipulate the morphology and function of the IHC synapse. Although partial-deletion mutants lacking functional bassoon (Bsn(ΔEx4/5)) had a near-complete loss of ribbons from the synapses (up to 88% ribbonless synapses), gene-trap mutants (Bsn(gt)) showed weak residual expression of bassoon and 56% ribbonless synapses, whereas the remaining 44% had a loosely anchored ribbon. Patch-clamp recordings and synaptic CaV1.3 immunolabeling indicated a larger number of Ca(2+) channels for Bsn(gt) IHCs compared with Bsn(ΔEx4/5) IHCs and for Bsn(gt) ribbon-occupied versus Bsn(gt) ribbonless synapses. An intermediate phenotype of Bsn(gt) IHCs was also found by membrane capacitance measurements for sustained exocytosis, but not for the size of the readily releasable vesicle pool. The frequency and amplitude of EPSCs were reduced in Bsn(ΔEx4/5) mouse SGNs, whereas their postsynaptic AMPA receptor clusters were largely unaltered. Sound coding in SGN, assessed by recordings of single auditory nerve fibers and their population responses in vivo, was similarly affected in Bsn(gt) and Bsn(ΔEx4/5) mice. Both genotypes showed impaired sound onset coding and reduced evoked and spontaneous spike rates. In summary, reduced bassoon expression or complete lack of full-length bassoon impaired sound encoding to a similar extent, which is consistent with the comparable reduction of the readily releasable vesicle pool. This suggests that the remaining loosely anchored ribbons in Bsn(gt) IHCs were functionally inadequate or that ribbon independent mechanisms dominated the coding deficit.
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33
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Schröder MS, Stellmacher A, Romorini S, Marini C, Montenegro-Venegas C, Altrock WD, Gundelfinger ED, Fejtova A. Regulation of presynaptic anchoring of the scaffold protein Bassoon by phosphorylation-dependent interaction with 14-3-3 adaptor proteins. PLoS One 2013; 8:e58814. [PMID: 23516560 PMCID: PMC3597591 DOI: 10.1371/journal.pone.0058814] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 02/07/2013] [Indexed: 01/10/2023] Open
Abstract
The proper organization of the presynaptic cytomatrix at the active zone is essential for reliable neurotransmitter release from neurons. Despite of the virtual stability of this tightly interconnected proteinaceous network it becomes increasingly clear that regulated dynamic changes of its composition play an important role in the processes of synaptic plasticity. Bassoon, a core component of the presynaptic cytomatrix, is a key player in structural organization and functional regulation of presynaptic release sites. It is one of the most highly phosphorylated synaptic proteins. Nevertheless, to date our knowledge about functions mediated by any one of the identified phosphorylation sites of Bassoon is sparse. In this study, we have identified an interaction of Bassoon with the small adaptor protein 14-3-3, which depends on phosphorylation of the 14-3-3 binding motif of Bassoon. In vitro phosphorylation assays indicate that phosphorylation of the critical Ser-2845 residue of Bassoon can be mediated by a member of the 90-kDa ribosomal S6 protein kinase family. Elimination of Ser-2845 from the 14-3-3 binding motif results in a significant decrease of Bassoon's molecular exchange rates at synapses of living rat neurons. We propose that the phosphorylation-induced 14-3-3 binding to Bassoon modulates its anchoring to the presynaptic cytomatrix. This regulation mechanism might participate in molecular and structural presynaptic remodeling during synaptic plasticity.
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Affiliation(s)
- Markus S. Schröder
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Anne Stellmacher
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Stefano Romorini
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Claudia Marini
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | | | - Wilko D. Altrock
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Science, Magdeburg, Germany
| | - Eckart D. Gundelfinger
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Science, Magdeburg, Germany
- * E-mail: (EDG); (AF)
| | - Anna Fejtova
- Department of Neurochemistry & Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- * E-mail: (EDG); (AF)
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Hradsky J, Mikhaylova M, Karpova A, Kreutz MR, Zuschratter W. Super-resolution microscopy of the neuronal calcium-binding proteins Calneuron-1 and Caldendrin. Methods Mol Biol 2013; 963:147-169. [PMID: 23296610 DOI: 10.1007/978-1-62703-230-8_10] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Calcium (Ca(2+)) signaling in neurons is mediated by plethora of calcium binding proteins with many of them belonging to the Calmodulin family of calcium sensors. Many studies have shown that the subcellular localization of neuronal EF-hand Ca(2+)-sensors is crucial for their cellular function. To overcome the resolution limit of classical fluorescence and confocal microscopy various imaging techniques have been developed recently that improve the resolution by an order of magnitude in all dimensions. This new microscope techniques make co-localization studies of Ca(2+)-binding proteins more reliable and help to get insights into the macromolecular organization of intracellular structures and signaling pathways beyond the diffraction limit of visible light.
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Affiliation(s)
- Johannes Hradsky
- Research Group, Neuroplasticity, Leibniz Institute for Neurobiology (LIN), Magdeburg, Germany
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A window into domain amplification through Piccolo in teleost fish. G3-GENES GENOMES GENETICS 2012; 2:1325-39. [PMID: 23173084 PMCID: PMC3484663 DOI: 10.1534/g3.112.003624] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 08/31/2012] [Indexed: 12/20/2022]
Abstract
I describe and characterize the extensive amplification of the zinc finger domain of Piccolo selectively in teleost fish. Piccolo and Bassoon are partially functionally redundant and play roles in regulating the pool of neurotransmitter-filled synaptic vesicles present at synapses. In mice, each protein contains two N-terminal zinc finger domains that have been implicated in interacting with synaptic vesicles. In all teleosts examined, both the Bassoon and Piccolo genes are duplicated. Both teleost bassoon genes and one piccolo gene show very similar domain structure and intron-exon organization to their mouse homologs. In contrast, in piccolo b a single exon that encodes a zinc finger domain is amplified 8 to 16 times in different teleost species. Analysis of the amplified exons suggests they were added and/or deleted from the gene as individual exons in rare events that are likely the result of unequal crossovers between homologous sequences. Surprisingly, the structure of the repeats from cod and zebrafish suggest that amplification of this exon has occurred independently multiple times in the teleost lineage. Based on the structure of the exons, I propose a model in which selection for high sequence similarity at the 5′ and 3′ ends of the exon drives amplification of the repeats and diversity in repeat length likely promotes the stability of the repeated exons by minimizing the likelihood of mispairing of adjacent repeat sequences. Further analysis of piccolo b in teleosts should provide a window through which to examine the process of domain amplification.
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Abstract
Vesicular trafficking of presynaptic and postsynaptic components is emerging as a general cellular mechanism for the delivery of scaffold proteins, ion channels, and receptors to nascent and mature synapses. However, the molecular mechanisms leading to the selection of cargos and their differential transport to subneuronal compartments are not well understood, in part because of the mixing of cargos at the plasma membrane and/or within endosomal compartments. In the present study, we have explored the cellular mechanisms of active zone precursor vesicle assembly at the Golgi in dissociated hippocampal neurons of Rattus norvegicus. Our studies show that Piccolo, Bassoon, and ELKS2/CAST exit the trans-Golgi network on a common vesicle that requires Piccolo and Bassoon for its proper assembly. In contrast, Munc13 and synaptic vesicle proteins use distinct sets of Golgi-derived transport vesicles, while RIM1α associates with vesicular membranes in a post-Golgi compartment. Furthermore, Piccolo and Bassoon are necessary for ELKS2/CAST to leave the Golgi in association with vesicles, and a core domain of Bassoon is sufficient to facilitate formation of these vesicles. While these findings support emerging principles regarding active zone differentiation, the cellular and molecular analyses reported here also indicate that the Piccolo-Bassoon transport vesicles leaving the Golgi may undergo further changes in protein composition before arriving at synaptic sites.
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37
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Molecular anatomy and physiology of exocytosis in sensory hair cells. Cell Calcium 2012; 52:327-37. [DOI: 10.1016/j.ceca.2012.05.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 05/08/2012] [Accepted: 05/14/2012] [Indexed: 11/23/2022]
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Kuhse J, Kalbouneh H, Schlicksupp A, Mükusch S, Nawrotzki R, Kirsch J. Phosphorylation of gephyrin in hippocampal neurons by cyclin-dependent kinase CDK5 at Ser-270 is dependent on collybistin. J Biol Chem 2012; 287:30952-66. [PMID: 22778260 DOI: 10.1074/jbc.m112.349597] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gephyrin is a scaffold protein essential for the postsynaptic clustering of inhibitory glycine and different subtypes of GABA(A) receptors. The cellular and molecular mechanisms involved in gephyrin-mediated receptor clustering are still not well understood. Here we provide evidence that the gephyrin-binding protein collybistin is involved in regulating the phosphorylation of gephyrin. We demonstrate that the widely used monoclonal antibody mAb7a is a phospho-specific antibody that allows the cellular and biochemical analysis of gephyrin phosphorylation at Ser-270. In addition, another neighbored epitope determinant was identified at position Thr-276. Analysis of the double mutant gephyrin(T276A,S277A) revealed significant reduction in gephyrin cluster formation and altered oligomerization behavior of gephyrin. Moreover, pharmacological inhibition of cyclin-dependent kinases in hippocampal neurons reduced postsynaptic gephyrin mAb7a immunoreactivities. In vitro phosphorylation assays and phosphopeptide competition experiments revealed a phosphorylation at Ser-270 depending on enzyme activities of cyclin-dependent kinases CDK1, -2, or -5. These data indicate that collybistin and cyclin-dependent kinases are involved in regulating the phosphorylation of gephyrin at postsynaptic membrane specializations.
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Affiliation(s)
- Jochen Kuhse
- Department of Anatomy and Cell Biology, University of Heidelberg, D-69120 Heidelberg, Germany.
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Körber C, Richter A, Kaiser M, Schlicksupp A, Mükusch S, Kuner T, Kirsch J, Kuhse J. Effects of distinct collybistin isoforms on the formation of GABAergic synapses in hippocampal neurons. Mol Cell Neurosci 2012; 50:250-9. [DOI: 10.1016/j.mcn.2012.05.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 05/06/2012] [Accepted: 05/25/2012] [Indexed: 11/25/2022] Open
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Hübler D, Rankovic M, Richter K, Lazarevic V, Altrock WD, Fischer KD, Gundelfinger ED, Fejtova A. Differential spatial expression and subcellular localization of CtBP family members in rodent brain. PLoS One 2012; 7:e39710. [PMID: 22745816 PMCID: PMC3382178 DOI: 10.1371/journal.pone.0039710] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 05/30/2012] [Indexed: 12/23/2022] Open
Abstract
C-terminal binding proteins (CtBPs) are well-characterized nuclear transcriptional co-regulators. In addition, cytoplasmic functions were discovered for these ubiquitously expressed proteins. These include the involvement of the isoform CtBP1-S/BARS50 in cellular membrane-trafficking processes and a role of the isoform RIBEYE as molecular scaffolds in ribbons, the presynaptic specializations of sensory synapses. CtBPs were suggested to regulate neuronal differentiation and they were implied in the control of gene expression during epileptogenesis. However, the expression patterns of CtBP family members in specific brain areas and their subcellular localizations in neurons in situ are largely unknown. Here, we performed comprehensive assessment of the expression of CtBP1 and CtBP2 in mouse brain at the microscopic and the ultra-structural levels using specific antibodies. We quantified and compared expression levels of both CtBPs in biochemically isolated brain fractions containing cellular nuclei or synaptic compartment. Our study demonstrates differential regional and subcellular expression patterns for the two CtBP family members in brain and reveals a previously unknown synaptic localization for CtBP2 in particular brain regions. Finally, we propose a mechanism of differential synapto-nuclear targeting of its splice variants CtBP2-S and CtBP2-L in neurons.
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Affiliation(s)
- Diana Hübler
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Marija Rankovic
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Karin Richter
- Institute of Biochemistry and Cell Biology, Otto-von-Guericke University, Magdeburg, Germany
| | - Vesna Lazarevic
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- German Center for Neurodegenerative Disorders (DZNE), Magdeburg Branch, Magdeburg, Germany
| | - Wilko D. Altrock
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Klaus-Dieter Fischer
- Institute of Biochemistry and Cell Biology, Otto-von-Guericke University, Magdeburg, Germany
| | - Eckart D. Gundelfinger
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Anna Fejtova
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
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Distinct subsets of Syt-IV/BDNF vesicles are sorted to axons versus dendrites and recruited to synapses by activity. J Neurosci 2012; 32:5398-413. [PMID: 22514304 DOI: 10.1523/jneurosci.4515-11.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
BDNF plays a critical role in the regulation of synaptic strength and is essential for long-term potentiation, a phenomenon that underlies learning and memory. However, whether BDNF acts in a diffuse manner or is targeted to specific neuronal subcompartments or synaptic sites to affect circuit function remains unknown. Here, using photoactivation of BDNF or syt-IV (a regulator of exocytosis present on BDNF-containing vesicles) in transfected rat hippocampal neurons, we discovered that distinct subsets of BDNF vesicles are targeted to axons versus dendrites and are not shared between these compartments. Moreover, syt-IV- and BDNF-harboring vesicles are recruited to both presynaptic and postsynaptic sites in response to increased neuronal activity. Finally, using syt-IV knockout mouse neurons, we found that syt-IV is necessary for both presynaptic and postsynaptic scaling of synaptic strength in response to changes in network activity. These findings demonstrate that BDNF-containing vesicles can be targeted to specific sites in neurons and suggest that syt-IV-regulated BDNF secretion is subject to spatial control to regulate synaptic function in a site-specific manner.
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Dean C, Dunning FM, Liu H, Bomba-Warczak E, Martens H, Bharat V, Ahmed S, Chapman ER. Axonal and dendritic synaptotagmin isoforms revealed by a pHluorin-syt functional screen. Mol Biol Cell 2012; 23:1715-27. [PMID: 22398727 PMCID: PMC3338438 DOI: 10.1091/mbc.e11-08-0707] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The synaptotagmins (syts) are a family of molecules that regulate membrane fusion. There are 17 mammalian syt isoforms, most of which are expressed in the brain. However, little is known regarding the subcellular location and function of the majority of these syts in neurons, largely due to a lack of isoform-specific antibodies. Here we generated pHluorin-syt constructs harboring a luminal domain pH sensor, which reports localization, pH of organelles to which syts are targeted, and the kinetics and sites of exocytosis and endocytosis. Of interest, only syt-1 and 2 are targeted to synaptic vesicles, whereas other isoforms selectively recycle in dendrites (syt-3 and 11), axons (syt-5, 7, 10, and 17), or both axons and dendrites (syt-4, 6, 9, and 12), where they undergo exocytosis and endocytosis with distinctive kinetics. Hence most syt isoforms localize to distinct secretory organelles in both axons and dendrites and may regulate neuropeptide/neurotrophin release to modulate neuronal function.
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Affiliation(s)
- Camin Dean
- Department of Neuroscience, Howard Hughes Medical Institute, University of Wisconsin, Madison, WI 53706, USA
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43
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Abstract
Recent studies indicate that synaptic vesicles (SVs) are continuously interchanged among nearby synapses at very significant rates. These dynamics and the lack of obvious barriers confining synaptic vesicles to specific synapses would seem to challenge the ability of synapses to maintain a constant amount of synaptic vesicles over prolonged time scales. Moreover, the extensive mobilization of synaptic vesicles associated with presynaptic activity might be expected to intensify this challenge. Here we examined the ability of individual presynaptic boutons of rat hippocampal neurons to maintain their synaptic vesicle content, and the degree to which this ability is affected by continuous activity. We found that the synaptic vesicle content of individual boutons belonging to the same axons gradually changed over several hours, and that these changes occurred independently of activity. Intermittent stimulation for 1 h accelerated rates of vesicle pool size change. Interestingly, however, following stimulation cessation, vesicle pool size change rates gradually converged with basal change rates. Over similar time scales, active zones (AZs) exhibited substantial remodeling; yet, unlike synaptic vesicles, AZ remodeling was not affected by the stimulation paradigms used here. These findings indicate that enhanced activity levels can increase synaptic vesicle redistribution among nearby synapses, but also highlight the presence of forces that act to restore particular set points in terms of SV contents, and support a role for active zones in preserving such set points. These findings also indicate, however, that neither AZ size nor SV content set points are particularly stable, questioning the long-term tenacity of presynaptic specializations.
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Abstract
In neurons L-type calcium currents function in gene regulation and synaptic plasticity, while excessive calcium influx leads to excitotoxicity and neurodegeneration. The major neuronal Ca(V)1.2 L-type channels are localized in clusters in dendritic shafts and spines. Whereas Ca(V)1.2 clusters remain stable during NMDA-induced synaptic depression, L-type calcium currents are rapidly downregulated during strong excitatory stimulation. Here we used fluorescence recovery after photobleaching (FRAP), live cell-labeling protocols, and single particle tracking (SPT) to analyze the turnover and surface traffic of Ca(V)1.2 in dendrites of mature cultured mouse and rat hippocampal neurons, respectively. FRAP analysis of channels extracellularly tagged with superecliptic pHluorin (Ca(V)1.2-SEP) demonstrated ∼20% recovery within 2 min without reappearance of clusters. Pulse-chase labeling showed that membrane-expressed Ca(V)1.2-HA is not internalized within1 h, while blocking dynamin-dependent endocytosis resulted in increased cluster density after 30 min. Together, these results suggest a turnover rate of clustered Ca(V)1.2s on the hour time scale. Direct recording of the lateral movement in the membrane using SPT demonstrated that dendritic Ca(V)1.2s show highly confined mobility with diffusion coefficients of ∼0.005 μm² s⁻¹. Consistent with the mobile Ca(V)1.2 fraction observed in FRAP, a ∼30% subpopulation of channels reversibly exchanged between confined and diffusive states. Remarkably, high potassium depolarization did not alter the recovery rates in FRAP or the diffusion coefficients in SPT analyses. Thus, an equilibrium of clustered and dynamic Ca(V)1.2s maintains stable calcium channel complexes involved in activity-dependent cell signaling, whereas the minor mobile channel pool in mature neurons allows limited capacity for short-term adaptations.
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45
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Choi S, Dickson RM, Lee JK, Yu J. Generation of luminescent noble metal nanodots in cell matrices. Photochem Photobiol Sci 2011; 11:274-8. [PMID: 22045007 DOI: 10.1039/c1pp05276d] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cell matrices were used as rich libraries to screen proteins for the production of luminescent silver and gold nanodots. The study indicates that the proteins for silver and gold nanodot protection are quite different. The identification of such proteins in future may enrich the family of luminescent nanodots.
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Affiliation(s)
- Sungmoon Choi
- Department of Chemistry Education, Seoul National University, 599 Gwanak-Ro, Gwanak-Gu, Seoul, 151-742, South Korea
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46
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Popiolek M, Ross JF, Charych E, Chanda P, Gundelfinger ED, Moss SJ, Brandon NJ, Pausch MH. D-amino acid oxidase activity is inhibited by an interaction with bassoon protein at the presynaptic active zone. J Biol Chem 2011; 286:28867-28875. [PMID: 21700703 DOI: 10.1074/jbc.m111.262063] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Schizophrenia is a highly heritable neuropsychiatric disorder affecting ∼1% of the world's population. Linkage and association studies have identified multiple candidate schizophrenia susceptibility genes whose functions converge on the glutamatergic neurotransmitter system. One such susceptibility gene encoding D-amino acid oxidase (DAO), an enzyme that metabolizes the NMDA receptor (NMDAR) co-agonist D-serine, has the potential to modulate NMDAR function in the context of schizophrenia. To further investigate its cellular regulation, we sought to identify DAO-interacting proteins that participate in its functional regulation in rat cerebellum, where DAO expression is especially high. Immunoprecipitation with DAO-specific antibodies and subsequent mass spectrometric analysis of co-precipitated proteins yielded 24 putative DAO-interacting proteins. The most robust interactions occurred with known components of the presynaptic active zone, such as bassoon (BSN) and piccolo (PCLO). The interaction of DAO with BSN was confirmed through co-immunoprecipitation assays using DAO- and BSN-specific antibodies. Moreover, DAO and BSN colocalized with one another in cultured cerebellar granule cells and in synaptic junction membrane protein fractions derived from rat cerebellum. The functional consequences of this interaction were studied through enzyme assay experiments, where DAO enzymatic activity was significantly inhibited as a result of its interaction with BSN. Taking these results together, we hypothesize that synaptic D-serine concentrations may be under tight regulation by a BSN-DAO complex. We therefore predict that this mechanism plays a role in the modulation of glutamatergic signaling through NMDARs. It also furthers our understanding of the biology underlying this potential therapeutic entry point for schizophrenia and other psychiatric disorders.
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Affiliation(s)
- Michael Popiolek
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340
| | - John F Ross
- Aileron Therapeutics, Cambridge, Massachusetts, Germany
| | - Erik Charych
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Pranab Chanda
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340
| | | | | | - Nicholas J Brandon
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340,.
| | - Mark H Pausch
- Neuroscience Research Unit, Pfizer Global Research and Development, Groton, Connecticut 06340,; Merck, West Point, Pennsylvania 19486
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47
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Bury LAD, Sabo SL. Coordinated trafficking of synaptic vesicle and active zone proteins prior to synapse formation. Neural Dev 2011; 6:24. [PMID: 21569270 PMCID: PMC3103415 DOI: 10.1186/1749-8104-6-24] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 05/10/2011] [Indexed: 11/10/2022] Open
Abstract
Background The proteins required for synaptic transmission are rapidly assembled at nascent synapses, but the mechanisms through which these proteins are delivered to developing presynaptic terminals are not understood. Prior to synapse formation, active zone proteins and synaptic vesicle proteins are transported along axons in distinct organelles referred to as piccolo-bassoon transport vesicles (PTVs) and synaptic vesicle protein transport vesicles (STVs), respectively. Although both PTVs and STVs are recruited to the same site in the axon, often within minutes of axo-dendritic contact, it is not known whether or how PTV and STV trafficking is coordinated before synapse formation. Results Here, using time-lapse confocal imaging of the dynamics of PTVs and STVs in the same axon, we show that vesicle trafficking is coordinated through at least two mechanisms. First, a significant proportion of STVs and PTVs are transported together before forming a stable terminal. Second, individual PTVs and STVs share pause sites within the axon. Importantly, for both STVs and PTVs, encountering the other type of vesicle increases their propensity to pause. To determine if PTV-STV interactions are important for pausing, PTV density was reduced in axons by expression of a dominant negative construct corresponding to the syntaxin binding domain of syntabulin, which links PTVs with their KIF5B motor. This reduction in PTVs had a minimal effect on STV pausing and movement, suggesting that an interaction between STVs and PTVs is not responsible for enhancing STV pausing. Conclusions Our results indicate that trafficking of STVs and PTVs is coordinated even prior to synapse development. This novel coordination of transport and pausing might provide mechanisms through which all of the components of a presynaptic terminal can be rapidly accumulated at sites of synapse formation.
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Affiliation(s)
- Luke A D Bury
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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48
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Grabrucker AM, Garner CC, Boeckers TM, Bondioli L, Ruozi B, Forni F, Vandelli MA, Tosi G. Development of novel Zn2+ loaded nanoparticles designed for cell-type targeted drug release in CNS neurons: in vitro evidences. PLoS One 2011; 6:e17851. [PMID: 21448455 PMCID: PMC3063171 DOI: 10.1371/journal.pone.0017851] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 02/10/2011] [Indexed: 01/20/2023] Open
Abstract
Intact synaptic function and plasticity are fundamental prerequisites to a healthy brain. Therefore, synaptic proteins are one of the major targets for drugs used as neuro-chemical therapeutics. Unfortunately, the majority of drugs is not able to cross the blood-brain barrier (BBB) and is therefore distributed within the CNS parenchyma. Here, we report the development of novel biodegradable Nanoparticles (NPs), made of poly-lactide-co-glycolide (PLGA) conjugated with glycopeptides that are able to cross the BBB and deliver for example Zn(2+) ions. We also provide a thorough characterization of loaded and unloaded NPs for their stability, cellular uptake, release properties, toxicity, and impact on cell trafficking. Our data reveal that these NPs are biocompatible, and can be used to elevate intracellular levels of Zn(2+). Importantly, by engineering the surface of NPs with antibodies against NCAM1 and CD44, we were able to selectively target neurons or glial cells, respectively. Our results indicate that these biodegradable NPs provide a potential new venue for the delivery Zn(2+) to the CNS and thus a means to explore the influence of altered zinc levels linked to neuropsychological disorders such as depression.
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Affiliation(s)
- Andreas M. Grabrucker
- Department of Psychiatry and Behavioral
Sciences, Stanford School of Medicine, Stanford University, Stanford,
California, United States of America
- Institute for Anatomy and Cell Biology, Ulm
University, Ulm, Germany
- * E-mail: (AMG); (GT)
| | - Craig C. Garner
- Department of Psychiatry and Behavioral
Sciences, Stanford School of Medicine, Stanford University, Stanford,
California, United States of America
| | | | - Lucia Bondioli
- Te.Far.T.I. Group, Pharmaceutical Technology,
Department of Pharmaceutical Science, University of Modena and Reggio Emilia,
Modena and Reggio Emilia, Italy
| | - Barbara Ruozi
- Te.Far.T.I. Group, Pharmaceutical Technology,
Department of Pharmaceutical Science, University of Modena and Reggio Emilia,
Modena and Reggio Emilia, Italy
| | - Flavio Forni
- Te.Far.T.I. Group, Pharmaceutical Technology,
Department of Pharmaceutical Science, University of Modena and Reggio Emilia,
Modena and Reggio Emilia, Italy
| | - Maria Angela Vandelli
- Te.Far.T.I. Group, Pharmaceutical Technology,
Department of Pharmaceutical Science, University of Modena and Reggio Emilia,
Modena and Reggio Emilia, Italy
| | - Giovanni Tosi
- Te.Far.T.I. Group, Pharmaceutical Technology,
Department of Pharmaceutical Science, University of Modena and Reggio Emilia,
Modena and Reggio Emilia, Italy
- * E-mail: (AMG); (GT)
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Schaz U, Föhr KJ, Liebau S, Fulda S, Koelch M, Fegert JM, Boeckers TM, Ludolph AG. Dose-dependent modulation of apoptotic processes by fluoxetine in maturing neuronal cells: an in vitro study. World J Biol Psychiatry 2011; 12:89-98. [PMID: 20735156 DOI: 10.3109/15622975.2010.506927] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVES Recent studies indicate that the selective serotonin reuptake inhibitor (SSRI) fluoxetine is not solely effective by the instant inhibition of the serotonin transporter (SERT) but also by its influence on mitotic and/or apoptotic processes. METHODS To investigate the effects of the compound in vitro, we treated neurons from different brain areas with increasing concentrations of fluoxetine. Additionally, human embryonic kidney (HEK-293) cells and HEK-293 cells stably expressing the SERT were used. Cell viability was quantified by MTT-assay and apoptosis via fluorescence-activated cell-sorting analyses. Fluoxetine's effect on the γ-aminobutyric acid (GABA) receptor was electrophysiologically investigated to test the hypothesis if a GABA-mimetic effect exists that might lead - additionally to the well-known N-methyl-D-aspartate (NMDA)-antagonism - to increased apoptosis in immature neurons. RESULTS In hippocampal, cortical, and both types of HEK-293 cells, viability decreased and apoptosis increased in a dose-dependent manner (0.5-75 μM). In contrast, in mesencephalic and striatal cells the viability was unchanged or even slightly stimulated up to 20 μM fluoxetine. An anti-apoptotic effect of concentrations below 10 μM was observed in these cells. The GABA(A) receptor was directly activated by fluoxetine. CONCLUSIONS We conclude that fluoxetine affects apoptotic processes independently from SERT expression. Since especially the combined GABA-mimetic and NMDA-antagonistic effects increase apoptosis in developing neuronal cells, whereas both effects are neuroprotective in adult neurons we hypothesise that these mechanisms explain the discrepancy of in vitro and in vivo studies.
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Affiliation(s)
- Ulrike Schaz
- Institute of Anatomy and Cell Biology, University of Ulm, Ulm, Germany
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Grabrucker AM, Knight MJ, Proepper C, Bockmann J, Joubert M, Rowan M, Nienhaus GU, Garner CC, Bowie JU, Kreutz MR, Gundelfinger ED, Boeckers TM. Concerted action of zinc and ProSAP/Shank in synaptogenesis and synapse maturation. EMBO J 2011; 30:569-81. [PMID: 21217644 PMCID: PMC3034012 DOI: 10.1038/emboj.2010.336] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 11/23/2010] [Indexed: 12/20/2022] Open
Abstract
ProSAP/Shank are scaffolding proteins that localize to the postsynaptic density (PSD). This study shows that Zn2+ ions directly regulate the localization and recruitment of Shank/ProSAP1/2 to PSDs to facilitate synapse formation and maturation. Neuronal morphology and number of synapses is not static, but can change in response to a variety of factors, a process called synaptic plasticity. These structural and molecular changes are believed to represent the basis for learning and memory, thereby underling both the developmental and activity-dependent remodelling of excitatory synapses. Here, we report that Zn2+ ions, which are highly enriched within the postsynaptic density (PSD), are able to influence the recruitment of ProSAP/Shank proteins to PSDs in a family member-specific manner during the course of synaptogenesis and synapse maturation. Through selectively overexpressing each family member at excitatory postsynapses and comparing this to shRNA-mediated knockdown, we could demonstrate that only the overexpression of zinc-sensitive ProSAP1/Shank2 or ProSAP2/Shank3 leads to increased synapse density, although all of them cause a decrease upon knockdown. Furthermore, depletion of synaptic Zn2+ along with the knockdown of zinc-insensitive Shank1 causes the rapid disintegration of PSDs and the loss of several postsynaptic molecules including Homer1, PSD-95 and NMDA receptors. These findings lead to the model that the concerted action of ProSAP/Shank and Zn2+ is essential for the structural integrity of PSDs and moreover that it is an important element of synapse formation, maturation and structural plasticity.
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