1
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Mele M, De Luca P, Santos AR, Vieira M, Salazar IL, Pinheiro PS, Duarte CB. GRASP1 ubiquitination regulates AMPA receptor surface expression and synaptic activity in cultured hippocampal neurons. FASEB J 2021; 35:e21763. [PMID: 34245609 DOI: 10.1096/fj.201903061rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 05/29/2021] [Accepted: 06/14/2021] [Indexed: 11/11/2022]
Abstract
The synaptic expression of glutamate receptors of the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) type is dynamically controlled by interaction with binding partners and auxiliary proteins. These proteins can be regulated by posttranslational modifications, including ubiquitination. In this work, we investigated the regulation of glutamate receptor interacting protein-associated protein 1 (GRASP1) by ubiquitin-dependent mechanisms and its impact on surface expression and activity of synaptic AMPA receptors. Cotransfection of GFP-ubiquitin decreased myc-GRASP1 protein levels in HEK293T cells, and this effect was inhibited upon transfection of an ubiquitin mutant that cannot be ubiquitinated on Lys48. In addition, transfection of cultured hippocampal neurons with GFP-ubiquitin reduced the dendritic levels of endogenous GRASP1 and decreased the surface expression of GluA1 AMPA receptor subunits, an effect that was partly reversed by cotransfection with GRASP1. Similarly, transfection of hippocampal neurons with GFP-ubiquitin decreased the amplitude of miniature excitatory postsynaptic currents (mEPSCs) mediated by Ca2+ -impermeable AMPA receptors, and this effect was abrogated by cotransfection of GRASP1. Together, the results show a role for ubiquitination in the regulation of the postsynaptic protein GRASP1, which has an impact on the surface distribution of AMPA receptors and on their activity at the synapse.
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Affiliation(s)
- Miranda Mele
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Pasqualino De Luca
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Ana Rita Santos
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Marta Vieira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Ivan L Salazar
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Paulo S Pinheiro
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Department of Life Sciences, University of Coimbra, Coimbra, Portugal
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2
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Historical perspective and progress on protein ubiquitination at glutamatergic synapses. Neuropharmacology 2021; 196:108690. [PMID: 34197891 DOI: 10.1016/j.neuropharm.2021.108690] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 06/07/2021] [Accepted: 06/22/2021] [Indexed: 12/23/2022]
Abstract
Transcription-translation coupling leads to the production of proteins that are key for controlling essential neuronal processes that include neuronal development and changes in synaptic strength. Although these events have been a prevailing theme in neuroscience, the regulation of proteins via posttranslational signaling pathways are equally relevant for these neuronal processes. Ubiquitin is one type of posttranslational modification that covalently attaches to its targets/substrates. Ubiquitination of proteins play a key role in multiple signaling pathways, the predominant being removal of its substrates by a large molecular machine called the proteasome. Here, I review 40 years of progress on ubiquitination in the nervous system at glutamatergic synapses focusing on axon pathfinding, synapse formation, presynaptic release, dendritic spine formation, and regulation of postsynaptic glutamate receptors. Finally, I elucidate emerging themes in ubiquitin biology that may challenge our current understanding of ubiquitin signaling in the nervous system.
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3
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van Gelder CAGH, Altelaar M. Neuroproteomics of the Synapse: Subcellular Quantification of Protein Networks and Signaling Dynamics. Mol Cell Proteomics 2021; 20:100087. [PMID: 33933679 PMCID: PMC8167277 DOI: 10.1016/j.mcpro.2021.100087] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/21/2021] [Accepted: 04/26/2021] [Indexed: 01/21/2023] Open
Abstract
One of the most fascinating features of the brain is its ability to adapt to its surroundings. Synaptic plasticity, the dynamic mechanism of functional and structural alterations in synaptic strength, is essential for brain functioning and underlies a variety of processes such as learning and memory. Although the molecular mechanisms underlying such rapid plasticity are not fully understood, a consensus exists on the important role of proteins. The study of these neuronal proteins using neuroproteomics has increased rapidly in the last decades, and advancements in MS-based proteomics have broadened our understanding of neuroplasticity exponentially. In this review, we discuss the trends in MS-based neuroproteomics for the study of synaptic protein-protein interactions and protein signaling dynamics, with a focus on sample types, different labeling and enrichment approaches, and data analysis and interpretation. We highlight studies from the last 5 years, with a focus on synapse structure, composition, functioning, or signaling and finally discuss some recent developments that could further advance the field of neuroproteomics.
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Affiliation(s)
- Charlotte A G H van Gelder
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands; Netherlands Proteomics Center, Utrecht, The Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands; Netherlands Proteomics Center, Utrecht, The Netherlands.
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4
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Synaptic Protein Degradation Controls Sexually Dimorphic Circuits through Regulation of DCC/UNC-40. Curr Biol 2020; 30:4128-4141.e5. [PMID: 32857970 PMCID: PMC7658809 DOI: 10.1016/j.cub.2020.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/13/2020] [Accepted: 08/03/2020] [Indexed: 12/27/2022]
Abstract
Sexually dimorphic circuits underlie behavioral differences between the sexes, yet the molecular mechanisms involved in their formation are poorly understood. We show here that sexually dimorphic connectivity patterns arise in C. elegans through local ubiquitin-mediated protein degradation in selected synapses of one sex but not the other. Specifically, synaptic degradation occurs via binding of the evolutionary conserved E3 ligase SEL-10/FBW7 to a phosphodegron binding site of the netrin receptor UNC-40/DCC (Deleted in Colorectal Cancer), resulting in degradation of UNC-40. In animals carrying an undegradable unc-40 gain-of-function allele, synapses were retained in both sexes, compromising the activity of the circuit without affecting neurite guidance. Thus, by decoupling the synaptic and guidance functions of the netrin pathway, we reveal a critical role for dimorphic protein degradation in controlling neuronal connectivity and activity. Additionally, the interaction between SEL-10 and UNC-40 is necessary not only for sex-specific synapse pruning, but also for other synaptic functions. These findings provide insight into the mechanisms that generate sex-specific differences in neuronal connectivity, activity, and function. Sex-specific synapse pruning during development is regulated by the ubiquitin pathway The E3 ligase SEL-10 targets the UNC-40 netrin receptor via binding to a CPD motif UNC-40 degradation leads to synapse removal only in hermaphrodites, not males CPD mutations disrupt synaptic functions of UNC-40, leaving axon guidance intact
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5
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Tomoda T, Yang K, Sawa A. Neuronal Autophagy in Synaptic Functions and Psychiatric Disorders. Biol Psychiatry 2020; 87:787-796. [PMID: 31542152 PMCID: PMC6986983 DOI: 10.1016/j.biopsych.2019.07.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 07/02/2019] [Accepted: 07/19/2019] [Indexed: 12/22/2022]
Abstract
Homeostatic maintenance of physiological functions is fundamental to organismal well-being. Disruption or imbalance in homeostasis results in functional disturbances at molecular, cellular, and tissue levels, leading to manifestation as physical and mental illnesses. Homeostatic imbalance is caused by a range of pathophysiological mechanisms, including disrupted reduction-oxidation reactions, inflammatory responses, metabolic disturbances, or failure in quality control of cellular proteins and organelles. However, the roles for the protein/organelle quality control in the regulation of behaviors, in particular of cognitive processes, had not been well documented, until recent reports finally supported this concept. The frontline studies in neuroscience have revealed that synaptic components (e.g., synaptic proteins, organelles, neurotransmitters and their receptors) are selectively degraded by autophagy, a cellular recycling machinery implicated in surveillance and quality control of proteins and organelles responsible for the maintenance of cellular homeostasis. Apart from the canonical role of autophagy in supporting cell viability, synaptic autophagy appears to regulate synapse remodeling and plasticity. Consistently, emerging evidence suggests novel roles of autophagy in memory encoding, information processing, or cognitive functions. In this review, we overview recent progress in understanding the roles of neuronal autophagy in homeostatic maintenance of synaptic functions, with particular focus on how disruptions in these processes may contribute to the pathophysiology of psychiatric disorders.
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Affiliation(s)
- Toshifumi Tomoda
- Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
| | - Kun Yang
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
| | - Akira Sawa
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
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6
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Feldmann LK, Le Prieult F, Felzen V, Thal SC, Engelhard K, Behl C, Mittmann T. Proteasome and Autophagy-Mediated Impairment of Late Long-Term Potentiation (l-LTP) after Traumatic Brain Injury in the Somatosensory Cortex of Mice. Int J Mol Sci 2019; 20:ijms20123048. [PMID: 31234472 PMCID: PMC6627835 DOI: 10.3390/ijms20123048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/17/2019] [Accepted: 06/19/2019] [Indexed: 12/21/2022] Open
Abstract
Traumatic brain injury (TBI) can lead to impaired cognition and memory consolidation. The acute phase (24–48 h) after TBI is often characterized by neural dysfunction in the vicinity of the lesion, but also in remote areas like the contralateral hemisphere. Protein homeostasis is crucial for synaptic long-term plasticity including the protein degradation systems, proteasome and autophagy. Still, little is known about the acute effects of TBI on synaptic long-term plasticity and protein degradation. Thus, we investigated TBI in a controlled cortical impact (CCI) model in the motor and somatosensory cortex of mice ex vivo-in vitro. Late long-term potentiation (l-LTP) was induced by theta-burst stimulation in acute brain slices after survival times of 1–2 days. Protein levels for the plasticity related protein calcium/calmodulin-dependent protein kinase II (CaMKII) was quantified by Western blots, and the protein degradation activity by enzymatical assays. We observed missing maintenance of l-LTP in the ipsilateral hemisphere, however not in the contralateral hemisphere after TBI. Protein levels of CaMKII were not changed but, interestingly, the protein degradation revealed bidirectional changes with a reduced proteasome activity and an increased autophagic flux in the ipsilateral hemisphere. Finally, LTP recordings in the presence of pharmacologically modified protein degradation systems also led to an impaired synaptic plasticity: bath-applied MG132, a proteasome inhibitor, or rapamycin, an activator of autophagy, both administered during theta burst stimulation, blocked the induction of LTP. These data indicate that alterations in protein degradation pathways likely contribute to cognitive deficits in the acute phase after TBI, which could be interesting for future approaches towards neuroprotective treatments early after traumatic brain injury.
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Affiliation(s)
- Lucia K Feldmann
- Institute for Physiology, UMC of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128 Mainz, Germany.
| | - Florie Le Prieult
- Institute for Physiology, UMC of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128 Mainz, Germany.
| | - Vanessa Felzen
- Institute for Pathobiochemistry, UMC of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128 Mainz, Germany.
| | - Serge C Thal
- Clinics for Anaesthesiology, UMC of the Johannes Gutenberg University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany.
| | - Kristin Engelhard
- Clinics for Anaesthesiology, UMC of the Johannes Gutenberg University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany.
| | - Christian Behl
- Institute for Pathobiochemistry, UMC of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128 Mainz, Germany.
| | - Thomas Mittmann
- Institute for Physiology, UMC of the Johannes Gutenberg University Mainz, Duesbergweg 6, 55128 Mainz, Germany.
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7
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Liang Y. Emerging Concepts and Functions of Autophagy as a Regulator of Synaptic Components and Plasticity. Cells 2019; 8:cells8010034. [PMID: 30634508 PMCID: PMC6357011 DOI: 10.3390/cells8010034] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 12/23/2018] [Accepted: 01/03/2019] [Indexed: 12/15/2022] Open
Abstract
Protein homeostasis (proteostasis) is crucial to the maintenance of neuronal integrity and function. As the contact sites between neurons, synapses rely heavily on precisely regulated protein-protein interactions to support synaptic transmission and plasticity processes. Autophagy is an effective degradative pathway that can digest cellular components and maintain cellular proteostasis. Perturbations of autophagy have been implicated in aging and neurodegeneration due to a failure to remove damaged proteins and defective organelles. Recent evidence has demonstrated that autophagosome formation is prominent at synaptic terminals and neuronal autophagy is regulated in a compartment-specific fashion. Moreover, synaptic components including synaptic proteins and vesicles, postsynaptic receptors and synaptic mitochondria are known to be degraded by autophagy, thereby contributing to the remodeling of synapses. Indeed, emerging studies indicate that modulation of autophagy may be required for different forms of synaptic plasticity and memory formation. In this review, I will discuss our current understanding of the important role of neuronal/synaptic autophagy in maintaining neuronal function by degrading synaptic components and try to propose a conceptual framework of how the degradation of synaptic components via autophagy might impact synaptic function and contribute to synaptic plasticity.
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Affiliation(s)
- YongTian Liang
- Neurogenetik, Institut für Biologie, Freie Universität Berlin, 14195 Berlin, Germany.
- NeuroCure, Cluster of Excellence, Charité Universitätsmedizin, 10117 Berlin, Germany.
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8
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Kohlbrenner EA, Shaskan N, Pietersen CY, Sonntag KC, Woo TUW. Gene expression profile associated with postnatal development of pyramidal neurons in the human prefrontal cortex implicates ubiquitin ligase E3 in the pathophysiology of schizophrenia onset. J Psychiatr Res 2018; 102:110-117. [PMID: 29635114 PMCID: PMC6347389 DOI: 10.1016/j.jpsychires.2018.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 03/17/2018] [Accepted: 03/25/2018] [Indexed: 11/25/2022]
Abstract
Schizophrenia is a neurodevelopmental disorder with the typical age of onset of overt symptoms and deficits occurring during late adolescence or early adulthood, coinciding with the final maturation of the cortical network involving the prefrontal cortex. These observations have led to the hypothesis that disturbances of the developmental events that take place in the prefrontal cortex during this period, specifically the remodeling of synaptic connectivities between pyramidal neurons, may contribute to the onset of illness. In this context, we investigated the gene expression changes of pyramidal neurons in the human prefrontal cortex during normal periadolescent development in order to gain insight into the possible molecular mechanisms involved in synaptic remodeling of pyramidal neuronal circuitry. Our data suggest that genes associated with the ubiquitination system, which has been implicated in the biology of synaptic plasticity, may play a major role. Among these genes, UBE3B, which encodes the ubiquitin ligase E3, was found to undergo periadolescent increase and was validated at the protein level to be upregulated during periadolescent development. Furthermore, we found that the density of UBE3B-immunoreactive pyramidal neurons was decreased in schizophrenia subjects, consistent with the result of a previous study of decreased UBE3B mRNA expression in pyramidal neurons in this illness. Altogether these findings point to the novel hypothesis that this specific ligase may play a role in the developmental pathogenesis of schizophrenia onset by possibly altering the synaptic remodeling process.
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Affiliation(s)
- Emily A. Kohlbrenner
- Laboratory for Cellular Neuropathology, Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478,Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478
| | - Noel Shaskan
- Laboratory for Cellular Neuropathology, Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478,Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478
| | - Charmaine Y. Pietersen
- Laboratory for Cellular Neuropathology, Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478,Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478
| | - Kai-C Sonntag
- Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478,Department of Psychiatry, Harvard Medical School, Boston, MA 02215
| | - Tsung-Ung W. Woo
- Laboratory for Cellular Neuropathology, Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478,Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478,Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA 02215,Department of Psychiatry, Harvard Medical School, Boston, MA 02215
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9
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Saavedra A, Ballesteros JJ, Tyebji S, Martínez-Torres S, Blázquez G, López-Hidalgo R, Azkona G, Alberch J, Martín ED, Pérez-Navarro E. Proteolytic Degradation of Hippocampal STEP 61 in LTP and Learning. Mol Neurobiol 2018; 56:1475-1487. [PMID: 29948948 DOI: 10.1007/s12035-018-1170-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 05/31/2018] [Indexed: 10/14/2022]
Abstract
Striatal-enriched protein tyrosine phosphatase (STEP) modulates key signaling molecules involved in synaptic plasticity and neuronal function. It is postulated that STEP opposes the development of long-term potentiation (LTP) and that it exerts a restraint on long-term memory (LTM). Here, we examined whether STEP61 levels are regulated during hippocampal LTP and after training in hippocampal-dependent tasks. We found that after inducing LTP by high frequency stimulation or theta-burst stimulation STEP61 levels were significantly reduced, with a concomitant increase of STEP33 levels, a product of calpain cleavage. Importantly, inhibition of STEP with TC-2153 improved LTP in hippocampal slices. Moreover, we observed that after training in the passive avoidance and the T-maze spontaneous alternation task, hippocampal STEP61 levels were significantly reduced, but STEP33 levels were unchanged. Yet, hippocampal BDNF content and TrkB levels were increased in trained mice, and it is known that BDNF promotes STEP degradation through the proteasome. Accordingly, hippocampal pTrkBTyr816, pPLCγTyr783, and protein ubiquitination levels were increased in T-SAT trained mice. Remarkably, injection of the TrkB antagonist ANA-12 (2 mg/Kg, but not 0.5 mg/Kg) elicited LTM deficits and promoted STEP61 accumulation in the hippocampus. Also, STEP knockout mice outperformed wild-type animals in an age- and test-dependent manner. Summarizing, STEP61 undergoes proteolytic degradation in conditions leading to synaptic strengthening and memory formation, thus highlighting its role as a molecular constrain, which is removed to enable the activation of pathways important for plasticity processes.
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Affiliation(s)
- Ana Saavedra
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, C/ Casanova, 143 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Jesús J Ballesteros
- Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain.,Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.,The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Shiraz Tyebji
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, C/ Casanova, 143 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Infection and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Australia
| | - Sara Martínez-Torres
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, C/ Casanova, 143 08036, Barcelona, Catalonia, Spain.,Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Gloria Blázquez
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, C/ Casanova, 143 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Rosa López-Hidalgo
- Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain.,Grupo de Patología Celular y Molecular del Alcohol, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Garikoitz Azkona
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, C/ Casanova, 143 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Jordi Alberch
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, C/ Casanova, 143 08036, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Eduardo D Martín
- Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain.,Instituto Cajal, CSIC, Madrid, Spain
| | - Esther Pérez-Navarro
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, C/ Casanova, 143 08036, Barcelona, Catalonia, Spain. .,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain. .,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
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10
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Saldate JJ, Shiau J, Cazares VA, Stuenkel EL. The ubiquitin-proteasome system functionally links neuronal Tomosyn-1 to dendritic morphology. J Biol Chem 2017; 293:2232-2246. [PMID: 29269412 DOI: 10.1074/jbc.m117.815514] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/02/2017] [Indexed: 12/29/2022] Open
Abstract
Altering the expression of Tomosyn-1 (Tomo-1), a soluble, R-SNARE domain-containing protein, significantly affects behavior in mice, Drosophila, and Caenorhabditis elegans Yet, the mechanisms that modulate Tomo-1 expression and its regulatory activity remain poorly defined. Here, we found that Tomo-1 expression levels influence postsynaptic spine density. Tomo-1 overexpression increased dendritic spine density, whereas Tomo-1 knockdown (KD) decreased spine density. These findings identified a novel action of Tomo-1 on dendritic spines, which is unique because it occurs independently of Tomo-1's C-terminal R-SNARE domain. We also demonstrated that the ubiquitin-proteasome system (UPS), which is known to influence synaptic strength, dynamically regulates Tomo-1 protein levels. Immunoprecipitated and affinity-purified Tomo-1 from cultured rat hippocampal neurons was ubiquitinated, and the levels of ubiquitinated Tomo-1 dramatically increased upon pharmacological proteasome blockade. Moreover, Tomo-1 ubiquitination appeared to be mediated through an interaction with the E3 ubiquitin ligase HRD1, as immunoprecipitation of Tomo-1 from neurons co-precipitated HRD1, and this interaction increases upon proteasome inhibition. Further, in vitro reactions indicated direct, HRD1 concentration-dependent Tomo-1 ubiquitination. We also noted that the UPS regulates both Tomo-1 expression and functional output, as HRD1 KD in hippocampal neurons increased Tomo-1 protein level and dendritic spine density. Notably, the effect of HRD1 KD on spine density was mitigated by additional KD of Tomo-1, indicating a direct HRD1/Tomo-1 effector relationship. In summary, our results indicate that the UPS is likely to participate in tuning synaptic efficacy and spine dynamics by precise regulation of neuronal Tomo-1 levels.
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Affiliation(s)
| | - Jason Shiau
- the Department of Molecular and Integrative Physiology, Medical School, University of Michigan, Ann Arbor, Michigan 48109-5624
| | - Victor A Cazares
- the Department of Molecular and Integrative Physiology, Medical School, University of Michigan, Ann Arbor, Michigan 48109-5624
| | - Edward L Stuenkel
- From the Neuroscience Graduate Program and .,the Department of Molecular and Integrative Physiology, Medical School, University of Michigan, Ann Arbor, Michigan 48109-5624
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11
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Grimaldo L, Sandoval A, Garza-López E, Felix R. Involvement of Parkin in the ubiquitin proteasome system-mediated degradation of N-type voltage-gated Ca2+ channels. PLoS One 2017; 12:e0185289. [PMID: 28957379 PMCID: PMC5619756 DOI: 10.1371/journal.pone.0185289] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 09/08/2017] [Indexed: 01/27/2023] Open
Abstract
N-type calcium (CaV2.2) channels are widely expressed in the brain and the peripheral nervous system, where they play important roles in the regulation of transmitter release. Although CaV2.2 channel expression levels are precisely regulated, presently little is known regarding the molecules that mediate its synthesis and degradation. Previously, by using a combination of biochemical and functional analyses, we showed that the complex formed by the light chain 1 of the microtubule-associated protein 1B (LC1-MAP1B) and the ubiquitin-proteasome system (UPS) E2 enzyme UBE2L3, may interact with the CaV2.2 channels promoting ubiquitin-mediated degradation. The present report aims to gain further insights into the possible mechanism of degradation of the neuronal CaV2.2 channel by the UPS. First, we identified the enzymes UBE3A and Parkin, members of the UPS E3 ubiquitin ligase family, as novel CaV2.2 channel binding partners, although evidence to support a direct protein-protein interaction is not yet available. Immunoprecipitation assays confirmed the interaction between UBE3A and Parkin with CaV2.2 channels heterologously expressed in HEK-293 cells and in neural tissues. Parkin, but not UBE3A, overexpression led to a reduced CaV2.2 protein level and decreased current density. Electrophysiological recordings performed in the presence of MG132 prevented the actions of Parkin suggesting enhanced channel proteasomal degradation. Together these results unveil a novel functional coupling between Parkin and the CaV2.2 channels and provide a novel insight into the basic mechanisms of CaV channels protein quality control and functional expression.
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Affiliation(s)
- Lizbeth Grimaldo
- Department of Cell Biology, Centre for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico
| | - Alejandro Sandoval
- Faculty of Superior Studies Iztacala, National Autonomous University of Mexico (UNAM), Tlalnepantla, Mexico
| | - Edgar Garza-López
- Department of Cell Biology, Centre for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico
| | - Ricardo Felix
- Department of Cell Biology, Centre for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico
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12
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Abstract
Maintaining synaptic integrity and function depends on the continuous removal and degradation of aged or damaged proteins. Synaptic protein degradation has received considerable attention in the context of synaptic plasticity and growing interest in relation to neurodegenerative and other disorders. Conversely, less attention has been given to constitutive, ongoing synaptic protein degradation and the roles canonical degradation pathways play in these processes. Here we briefly review recent progress on this topic and new experimental approaches which have expedited such progress and highlight several emerging principles. These include the realization that synaptic proteins typically have unusually long lifetimes, as might be expected from the remote locations of most synaptic sites; the possibility that degradation pathways can change with time from synthesis, cellular context, and physiological input; and that degradation pathways, other than ubiquitin-proteasomal-mediated degradation, might play key roles in constitutive protein degradation at synaptic sites. Finally, we point to the importance of careful experimental design and sufficiently sensitive techniques for studying synaptic protein degradation, which bring into account their slow turnover rates and complex life cycles.
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Affiliation(s)
- Laurie D Cohen
- Technion Faculty of Medicine, Rappaport Institute and Network Biology Research Laboratories, Technion City, Haifa, 32000, Israel
| | - Noam E Ziv
- Technion Faculty of Medicine, Rappaport Institute and Network Biology Research Laboratories, Technion City, Haifa, 32000, Israel
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13
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Park DI, Dournes C, Sillaber I, Ising M, Asara JM, Webhofer C, Filiou MD, Müller MB, Turck CW. Delineation of molecular pathway activities of the chronic antidepressant treatment response suggests important roles for glutamatergic and ubiquitin-proteasome systems. Transl Psychiatry 2017; 7:e1078. [PMID: 28375208 PMCID: PMC5416684 DOI: 10.1038/tp.2017.39] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 12/28/2016] [Accepted: 01/17/2017] [Indexed: 12/11/2022] Open
Abstract
The aim of this study was to identify molecular pathways related to antidepressant response. We administered paroxetine to the DBA/2J mice for 28 days. Following the treatment, the mice were grouped into responders or non-responders depending on the time they spent immobile in the forced swim test. Hippocampal metabolomics and proteomics analyses revealed that chronic paroxetine treatment affects glutamate-related metabolite and protein levels differentially in the two groups. We found significant differences in the expression of N-methyl-d-aspartate receptor and neuronal nitric oxide synthase proteins between the two groups, without any significant alterations in the respective transcript levels. In addition, we found that chronic paroxetine treatment altered the levels of proteins associated with the ubiquitin-proteasome system (UPS). The soluble guanylate cyclase-β1, proteasome subunit α type-2 and ubiquitination levels were also affected in peripheral blood mononuclear cells from antidepressant responder and non-responder patients suffering from major depressive disorder. We submit that the glutamatergic system and UPS have a crucial role in the antidepressant treatment response in both mice and humans.
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Affiliation(s)
- D I Park
- Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany
| | - C Dournes
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | | | - M Ising
- Department of Clinical Research, Max Planck Institute of Psychiatry, Munich, Germany
| | - J M Asara
- Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA, USA,Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - C Webhofer
- Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany
| | - M D Filiou
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany
| | - M B Müller
- Division of Experimental Psychiatry, Focus Program Translational Neuroscience, Department of Psychiatry and Psychotherapy, Johannes Gutenberg University Medical Center, Mainz, Germany,Division of Experimental Psychiatry, Focus Program Translational Neuroscience, Department of Psychiatry and Psychotherapy, Johannes Gutenberg University Medical Center, 55128 Mainz, Germany or , Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Kraepelinstrasse 2-10, 80804 Munich, Germany. E-mail: or
| | - C W Turck
- Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany,Division of Experimental Psychiatry, Focus Program Translational Neuroscience, Department of Psychiatry and Psychotherapy, Johannes Gutenberg University Medical Center, 55128 Mainz, Germany or , Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Kraepelinstrasse 2-10, 80804 Munich, Germany. E-mail: or
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14
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Ubiquitin Ligase RNF138 Promotes Episodic Ataxia Type 2-Associated Aberrant Degradation of Human Ca v2.1 (P/Q-Type) Calcium Channels. J Neurosci 2017; 37:2485-2503. [PMID: 28167673 DOI: 10.1523/jneurosci.3070-16.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 01/09/2017] [Accepted: 01/31/2017] [Indexed: 11/21/2022] Open
Abstract
Voltage-gated CaV2.1 channels comprise a pore-forming α1A subunit with auxiliary α2δ and β subunits. CaV2.1 channels play an essential role in regulating synaptic signaling. Mutations in the human gene encoding the CaV2.1 subunit are associated with the cerebellar disease episodic ataxia type 2 (EA2). Several EA2-causing mutants exhibit impaired protein stability and exert dominant-negative suppression of CaV2.1 wild-type (WT) protein expression via aberrant proteasomal degradation. Here, we set out to delineate the protein degradation mechanism of human CaV2.1 subunit by identifying RNF138, an E3 ubiquitin ligase, as a novel CaV2.1-binding partner. In neurons, RNF138 and CaV2.1 coexist in the same protein complex and display notable subcellular colocalization at presynaptic and postsynaptic regions. Overexpression of RNF138 promotes polyubiquitination and accelerates protein turnover of CaV2.1. Disrupting endogenous RNF138 function with a mutant (RNF138-H36E) or shRNA infection significantly upregulates the CaV2.1 protein level and enhances CaV2.1 protein stability. Disrupting endogenous RNF138 function also effectively rescues the defective protein expression of EA2 mutants, as well as fully reversing EA2 mutant-induced excessive proteasomal degradation of CaV2.1 WT subunits. RNF138-H36E coexpression only partially restores the dominant-negative effect of EA2 mutants on CaV2.1 WT functional expression, which can be attributed to defective membrane trafficking of CaV2.1 WT in the presence of EA2 mutants. We propose that RNF138 plays a critical role in the homeostatic regulation of CaV2.1 protein level and functional expression and that RNF138 serves as the primary E3 ubiquitin ligase promoting EA2-associated aberrant degradation of human CaV2.1 subunits.SIGNIFICANCE STATEMENT Loss-of-function mutations in the human CaV2.1 subunit are linked to episodic ataxia type 2 (EA2), a dominantly inherited disease characterized by paroxysmal attacks of ataxia and nystagmus. EA2-causing mutants may exert dominant-negative effects on the CaV2.1 wild-type subunit via aberrant proteasomal degradation. The molecular nature of the CaV2.1 ubiquitin-proteasome degradation pathway is currently unknown. The present study reports the first identification of an E3 ubiquitin ligase for CaV2.1, RNF138. CaV2.1 protein stability is dynamically regulated by RNF138 and auxiliary α2δ and β subunits. We provide a proof of concept that protecting the human CaV2.1 subunit from excessive proteasomal degradation with specific interruption of endogenous RNF138 function may partially contribute to the future development of a novel therapeutic strategy for EA2 patients.
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15
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Cullin 7 mediates proteasomal and lysosomal degradations of rat Eag1 potassium channels. Sci Rep 2017; 7:40825. [PMID: 28098200 PMCID: PMC5241692 DOI: 10.1038/srep40825] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 12/12/2016] [Indexed: 11/08/2022] Open
Abstract
Mammalian Eag1 (Kv10.1) potassium (K+) channels are widely expressed in the brain. Several mutations in the gene encoding human Eag1 K+ channel have been associated with congenital neurodevelopmental anomalies. Currently very little is known about the molecules mediating protein synthesis and degradation of Eag1 channels. Herein we aim to ascertain the protein degradation mechanism of rat Eag1 (rEag1). We identified cullin 7 (Cul7), a member of the cullin-based E3 ubiquitin ligase family, as a novel rEag1 binding partner. Immunoprecipitation analyses confirmed the interaction between Cul7 and rEag1 in heterologous cells and neuronal tissues. Cul7 and rEag1 also exhibited significant co-localization at synaptic regions in neurons. Over-expression of Cul7 led to reduced protein level, enhanced ubiquitination, accelerated protein turn-over, and decreased current density of rEag1 channels. We provided further biochemical and morphological evidence suggesting that Cul7 targeted endoplasmic reticulum (ER)- and plasma membrane-localized rEag1 to the proteasome and the lysosome, respectively, for protein degradation. Cul7 also contributed to protein degradation of a disease-associated rEag1 mutant. Together, these results indicate that Cul7 mediates both proteasomal and lysosomal degradations of rEag1. Our findings provide a novel insight to the mechanisms underlying ER and peripheral protein quality controls of Eag1 channels.
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16
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Hakim V, Cohen LD, Zuchman R, Ziv T, Ziv NE. The effects of proteasomal inhibition on synaptic proteostasis. EMBO J 2016; 35:2238-2262. [PMID: 27613546 PMCID: PMC5069550 DOI: 10.15252/embj.201593594] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 08/08/2016] [Indexed: 01/03/2023] Open
Abstract
Synaptic function crucially depends on uninterrupted synthesis and degradation of synaptic proteins. While much has been learned on synaptic protein synthesis, little is known on the routes by which synaptic proteins are degraded. Here we systematically studied how inhibition of the ubiquitin-proteasome system (UPS) affects the degradation rates of thousands of neuronal and synaptic proteins. We identified a group of proteins, including several proteins related to glutamate receptor trafficking, whose degradation rates were significantly slowed by UPS inhibition. Unexpectedly, however, degradation rates of most synaptic proteins were not significantly affected. Interestingly, many of the differential effects of UPS inhibition were readily explained by a quantitative framework that considered known metabolic turnover rates for the same proteins. In contrast to the limited effects on protein degradation, UPS inhibition profoundly and preferentially suppressed the synthesis of a large number of synaptic proteins. Our findings point to the importance of the UPS in the degradation of certain synaptic proteins, yet indicate that under basal conditions most synaptic proteins might be degraded through alternative pathways.
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Affiliation(s)
- Vicky Hakim
- The Rappaport Faculty of Medicine and Research Institute, Haifa, Israel.,Network Biology Research Laboratories, Technion - Israel Institute of Technology, Haifa, Israel
| | - Laurie D Cohen
- The Rappaport Faculty of Medicine and Research Institute, Haifa, Israel.,Network Biology Research Laboratories, Technion - Israel Institute of Technology, Haifa, Israel
| | - Rina Zuchman
- Smoler Proteomics Center, Faculty of Biology, Technion, Haifa, Israel
| | - Tamar Ziv
- Smoler Proteomics Center, Faculty of Biology, Technion, Haifa, Israel
| | - Noam E Ziv
- The Rappaport Faculty of Medicine and Research Institute, Haifa, Israel .,Network Biology Research Laboratories, Technion - Israel Institute of Technology, Haifa, Israel
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17
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The life cycle of the 26S proteasome: from birth, through regulation and function, and onto its death. Cell Res 2016; 26:869-85. [PMID: 27444871 PMCID: PMC4973335 DOI: 10.1038/cr.2016.86] [Citation(s) in RCA: 213] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The 26S proteasome is a large, ∼2.5 MDa, multi-catalytic ATP-dependent protease complex that serves as the degrading arm of the ubiquitin system, which is the major pathway for regulated degradation of cytosolic, nuclear and membrane proteins in all eukaryotic organisms.
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18
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Caputi FF, Carboni L, Mazza D, Candeletti S, Romualdi P. Cocaine and ethanol target 26S proteasome activity and gene expression in neuroblastoma cells. Drug Alcohol Depend 2016; 161:265-75. [PMID: 26922280 DOI: 10.1016/j.drugalcdep.2016.02.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 01/26/2016] [Accepted: 02/05/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND Ethanol and cocaine are widely abused drugs triggering long-lasting changes in neuronal circuits and synaptic transmission through the regulation of enzyme activity and gene expression. Compelling evidence indicates that the ubiquitin-proteasome system plays a role in the molecular changes induced by addictive substances, impacting on several mechanisms implicated in abuse. The goal of these studies was to evaluate the effects of cocaine or ethanol on proteasome activity in neuroblastoma cells. Moreover, the gene expression of specific subunits was assessed. METHODS Chymotrypsin-like activity was measured after 2 h, 24 h, and 48 h exposure to 5 μM cocaine or 40 mM ethanol. Proteasome subunit transcripts were evaluated by qPCR at the same time-points. RESULTS Treatments modified proteasome function in opposite directions, since cocaine increased and ethanol reduced chymotrypsin-like activity. Interestingly, we observed gene expression alterations induced by these drugs. In the core particle, the β1 and α5 subunits were mainly up-regulated by cocaine, whereas α6 transcripts were mostly decreased. β2 and β5 did not change. Similarly, ethanol exposure generally increased β1 and α5 mRNAs. Moreover, the β2 subunit was significantly up-regulated by ethanol only. The β5 and α6 subunits were not altered. In the regulatory particle, Rpt3 was increased by cocaine exposure, whereas it was reduced by ethanol. No significant Rpn9 alterations were observed. CONCLUSIONS These findings support the notion that addictive substances regulate proteasome function, contributing to the dysregulations related to drug abuse since the availability of adequate subunit amounts is necessary for proper complex assembly and function.
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Affiliation(s)
- Francesca Felicia Caputi
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-University of Bologna, Irnerio 48, 40126 Bologna, Italy.
| | - Lucia Carboni
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-University of Bologna, Irnerio 48, 40126 Bologna, Italy
| | - Daria Mazza
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-University of Bologna, Irnerio 48, 40126 Bologna, Italy
| | - Sanzio Candeletti
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-University of Bologna, Irnerio 48, 40126 Bologna, Italy
| | - Patrizia Romualdi
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-University of Bologna, Irnerio 48, 40126 Bologna, Italy
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19
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Ozawa M, Chambers JK, Uchida K, Nakayama H. The Relation between canine cognitive dysfunction and age-related brain lesions. J Vet Med Sci 2016; 78:997-1006. [PMID: 26922972 PMCID: PMC4937160 DOI: 10.1292/jvms.15-0624] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Canine cognitive dysfunction (CCD) is a syndrome that manifests itself in abnormal behaviors, such as
disorientation and wandering. β-amyloid deposition in the brain, including the senile plaque (SP) and cerebral
amyloid angiopathy (CAA), has been suggested as a major cause of the syndrome. However, the pathological
significance of β-amyloid deposition in CCD dogs remains unclear. The present study was conducted using 16
dogs aged 10 years or older to clarify the relationship between the age-related histopathological lesions,
such as β-amyloid deposition, in the brain and the clinical symptoms of CCD as evaluated in a questionnaire
previously established in a large survey. In addition, age-related brain lesions were assessed in 37 dogs. The
pathological lesions were evaluated by the severity of β-amyloid deposition (SP and CAA), the amount of
ubiquitin-positive granules (UBQ), GFAP-positive astrocytes, Iba-1-positive microglia and Nissle
stain-positive nerve cells. The results revealed that there was no significant correlation between the
severities of canine SP and CCD. The SP increased until 14 years old, but decreased thereafter, although the
incidence of CCD is high at these ages. The CAA consistently increased with age, but did not correlate greatly
with the CCD score. In contrast, the increases of UBQ, astrocytes and microglia were significantly correlated
with CCD. Thus, the impairment in the synapse and/or myelin suggested by increased UBQ and glial activation
might be involved in CCD pathogenesis, but β-amyloid deposition, especially SP, is not a direct pathogenic
factor of CCD.
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Affiliation(s)
- Makiko Ozawa
- Department of Veterinary Pathology, the University of Tokyo, Tokyo 113-8657, Japan
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20
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Brai E, Marathe S, Astori S, Fredj NB, Perry E, Lamy C, Scotti A, Alberi L. Notch1 Regulates Hippocampal Plasticity Through Interaction with the Reelin Pathway, Glutamatergic Transmission and CREB Signaling. Front Cell Neurosci 2015; 9:447. [PMID: 26635527 PMCID: PMC4659909 DOI: 10.3389/fncel.2015.00447] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/02/2015] [Indexed: 01/22/2023] Open
Abstract
Notch signaling plays a crucial role in adult brain function such as synaptic plasticity, memory and olfaction. Several reports suggest an involvement of this pathway in neurodegenerative dementia. Yet, to date, the mechanism underlying Notch activity in mature neurons remains unresolved. In this work, we investigate how Notch regulates synaptic potentiation and contributes to the establishment of memory in mice. We observe that Notch1 is a postsynaptic receptor with functional interactions with the Reelin receptor, apolipoprotein E receptor 2 (ApoER2) and the ionotropic receptor, N-methyl-D-aspartate receptor (NMDAR). Targeted loss of Notch1 in the hippocampal CA fields affects Reelin signaling by influencing Dab1 expression and impairs the synaptic potentiation achieved through Reelin stimulation. Further analysis indicates that loss of Notch1 affects the expression and composition of the NMDAR but not AMPAR. Glutamatergic signaling is further compromised through downregulation of CamKII and its secondary and tertiary messengers resulting in reduced cAMP response element-binding (CREB) signaling. Our results identify Notch1 as an important regulator of mechanisms involved in synaptic plasticity and memory formation. These findings emphasize the possible involvement of this signaling receptor in dementia.
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Affiliation(s)
- Emanuele Brai
- Department of Medicine, Institute of Anatomy, University of Fribourg Fribourg, Switzerland
| | - Swananda Marathe
- Department of Medicine, Institute of Anatomy, University of Fribourg Fribourg, Switzerland
| | - Simone Astori
- Department of Fundamental Neurosciences, University of Lausanne Lausanne, Switzerland
| | - Naila Ben Fredj
- Department of Medicine, Institute of Anatomy, University of Fribourg Fribourg, Switzerland
| | - Elisabeth Perry
- Histology Core Laboratory, Department of Cellular Biology and Anatomy, Georgia Health Sciences University Augusta, GA, USA
| | - Christophe Lamy
- Department of Medicine, Institute of Anatomy, University of Fribourg Fribourg, Switzerland
| | - Alessandra Scotti
- Institute of Anatomy, Faculty of Medicine, University of Bern Bern, Switzerland
| | - Lavinia Alberi
- Department of Medicine, Institute of Anatomy, University of Fribourg Fribourg, Switzerland ; Unit of Pathology, Department of Medicine, University of Fribourg Fribourg, Switzerland
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21
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Bal’ NV, Balaban PM. Ubiquitin-dependent protein degradation is necessary for long-term plasticity and memory. NEUROCHEM J+ 2015. [DOI: 10.1134/s1819712415040042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Mollova MY, Katus HA, Backs J. Regulation of CaMKII signaling in cardiovascular disease. Front Pharmacol 2015; 6:178. [PMID: 26379551 PMCID: PMC4548452 DOI: 10.3389/fphar.2015.00178] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 08/10/2015] [Indexed: 01/08/2023] Open
Abstract
Heart failure (HF) is a major cause of death in the developed countries (Murray and Lopez, 1996; Koitabashi and Kass, 2012). Adverse cardiac remodeling that precedes heart muscle dysfunction is characterized by a myriad of molecular changes affecting the cardiomyocyte. Among these, alterations in protein kinase pathways play often an important mediator role since they link upstream pathologic stress signaling with downstream regulatory programs and thus affect both the structural and functional integrity of the heart muscle. In the context of cardiac disease, a profound understanding for the overriding mechanisms that regulate protein kinase activity (protein-protein interactions, post-translational modifications, or targeting via anchoring proteins) is crucial for the development of specific and effective pharmacological treatment strategies targeting the failing myocardium. In this review, we focus on several mechanisms of upstream regulation of Ca2+-calmodulin-dependent protein kinase II that play a relevant pathophysiological role in the development and progression of cardiovascular disease; precise targeting of these mechanisms might therefore represent novel and promising tools for prevention and treatment of HF.
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Affiliation(s)
- Mariya Y Mollova
- Research Unit Cardiac Epigenetics, Department of Cardiology, Angiology and Pneumology, University of Heidelberg , Heidelberg, Germany ; Department of Cardiology, Angiology and Pneumology, University of Heidelberg , Heidelberg, Germany ; Partner Site Heidelberg/Mannheim, German Center for Cardiovascular Research , Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, Angiology and Pneumology, University of Heidelberg , Heidelberg, Germany ; Partner Site Heidelberg/Mannheim, German Center for Cardiovascular Research , Heidelberg, Germany
| | - Johannes Backs
- Research Unit Cardiac Epigenetics, Department of Cardiology, Angiology and Pneumology, University of Heidelberg , Heidelberg, Germany ; Partner Site Heidelberg/Mannheim, German Center for Cardiovascular Research , Heidelberg, Germany
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23
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Differential role of the proteasome in the early and late phases of BDNF-induced facilitation of LTP. J Neurosci 2015; 35:3319-29. [PMID: 25716833 DOI: 10.1523/jneurosci.4521-14.2015] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The neurotrophin brain-derived neurotrophic factor (BDNF) mediates activity-dependent long-term changes of synaptic strength in the CNS. The effects of BDNF are partly mediated by stimulation of local translation, with consequent alterations in the synaptic proteome. The ubiquitin-proteasome system (UPS) also plays an important role in protein homeostasis at the synapse by regulating synaptic activity. However, whether BDNF acts on the UPS to mediate the effects on long-term synaptic potentiation (LTP) has not been investigated. In the present study, we show similar and nonadditive effects of BDNF and proteasome inhibition on the early phase of synaptic potentiation (E-LTP) induced by theta-burst stimulation of rat hippocampal CA1 synapses. The effects of BDNF were blocked by the proteasome activator IU1, suggesting that the neurotrophin acts by decreasing proteasome activity. Accordingly, BDNF downregulated the proteasome activity in cultured hippocampal neurons and in hippocampal synaptoneurosomes. Furthermore, BDNF increased the activity of the deubiquitinating enzyme UchL1 in synaptoneurosomes and upregulated free ubiquitin. In contrast to the effects on posttetanic potentiation, proteasome activity was required for BDNF-mediated LTP. These results show a novel role for BDNF in UPS regulation at the synapse, which is likely to act together with the increased translation activity in the regulation of the synaptic proteome during E-LTP.
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24
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Walters BJ, Zovkic IB. Building up and knocking down: an emerging role for epigenetics and proteasomal degradation in systems consolidation. Neuroscience 2015; 300:39-52. [PMID: 25967264 DOI: 10.1016/j.neuroscience.2015.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 04/18/2015] [Accepted: 05/03/2015] [Indexed: 01/30/2023]
Abstract
Memory formation is a protracted process in which recently acquired events are consolidated to produce stable and specific associations. Initially, newly acquired information undergoes cellular consolidation in the hippocampus, which transiently supports the storage of recently acquired memories. In contrast, remote, or "old" memories are maintained in the cortex and show almost complete independence from the hippocampus. Memories are transferred from the hippocampus to the cortex through a process termed systems consolidation. Emerging evidence suggests that recurrent activation, or "training" of the cortex by the hippocampus is vital to systems consolidation. This process involves prolonged waves of memory-related gene activity in the hippocampus and cortex long after the learning event has terminated. Indeed, molecular events occurring within hours and days of fear conditioning are essential for stabilizing and eventually transitioning the memory to the cortex. It is increasingly evident that molecular mechanisms that exhibit a capacity for prolonged activation may underlie systems consolidation. Processes that have the capacity to control protein abundance over long time scales, such as epigenetic modifications, are prime candidates for the molecular mechanism of systems consolidation. Indeed, recent work has established two types of epigenetic modifications as integral for systems consolidation. First, localized nucleosomal histone variant exchange and histone modifications are integral for early stages of systems consolidation, whereas DNA methylation appears to be utilized to form stable marks that support memory maintenance. Since systems consolidation also requires discrete and time-sensitive changes in protein abundance, additional mechanisms, such as protein degradation, need also be considered, although their role in systems consolidation has yet to be investigated. Here, we discuss the role of molecular mechanisms in systems consolidation and their implications for understanding how memories persist over time.
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Affiliation(s)
- B J Walters
- The Hospital for Sick Children, Department of Neuroscience and Mental Health, Toronto, ON, Canada
| | - I B Zovkic
- University of Toronto Mississauga, Department of Psychology, Mississauga, ON, Canada.
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