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Zhang T, Dolga AM, Eisel ULM, Schmidt M. Novel crosstalk mechanisms between GluA3 and Epac2 in synaptic plasticity and memory in Alzheimer's disease. Neurobiol Dis 2024; 191:106389. [PMID: 38142840 DOI: 10.1016/j.nbd.2023.106389] [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: 11/23/2023] [Revised: 12/19/2023] [Accepted: 12/19/2023] [Indexed: 12/26/2023] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease which accounts for the most cases of dementia worldwide. Impaired memory, including acquisition, consolidation, and retrieval, is one of the hallmarks in AD. At the cellular level, dysregulated synaptic plasticity partly due to reduced long-term potentiation (LTP) and enhanced long-term depression (LTD) underlies the memory deficits in AD. GluA3 containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are one of key receptors involved in rapid neurotransmission and synaptic plasticity. Recent studies revealed a novel form of GluA3 involved in neuronal plasticity that is dependent on cyclic adenosine monophosphate (cAMP), rather than N-methyl-d-aspartate (NMDA). However, this cAMP-dependent GluA3 pathway is specifically and significantly impaired by amyloid beta (Aβ), a pathological marker of AD. cAMP is a key second messenger that plays an important role in modulating memory and synaptic plasticity. We previously reported that exchange protein directly activated by cAMP 2 (Epac2), acting as a main cAMP effector, plays a specific and time-limited role in memory retrieval. From electrophysiological perspective, Epac2 facilities the maintenance of LTP, a cellular event closely associated with memory retrieval. Additionally, Epac2 was found to be involved in the GluA3-mediated plasticity. In this review, we comprehensively summarize current knowledge regarding the specific roles of GluA3 and Epac2 in synaptic plasticity and memory, and their potential association with AD.
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Affiliation(s)
- Tong Zhang
- Department of Molecular Pharmacology, University of Groningen, the Netherlands; Department of Molecular Neurobiology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen 9747 AG, Netherlands
| | - Amalia M Dolga
- Department of Molecular Pharmacology, University of Groningen, the Netherlands; Groningen Research Institute for Asthma and COPD, GRIAC, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Ulrich L M Eisel
- Department of Molecular Neurobiology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen 9747 AG, Netherlands
| | - Martina Schmidt
- Department of Molecular Pharmacology, University of Groningen, the Netherlands; Groningen Research Institute for Asthma and COPD, GRIAC, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
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Milham LT, Morris GP, Konen LM, Rentsch P, Avgan N, Vissel B. Quantification of AMPA receptor subunits and RNA editing-related proteins in the J20 mouse model of Alzheimer's disease by capillary western blotting. Front Mol Neurosci 2024; 16:1338065. [PMID: 38299128 PMCID: PMC10828003 DOI: 10.3389/fnmol.2023.1338065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 12/29/2023] [Indexed: 02/02/2024] Open
Abstract
Introduction Accurate modelling of molecular changes in Alzheimer's disease (AD) dementia is crucial for understanding the mechanisms driving neuronal pathology and for developing treatments. Synaptic dysfunction has long been implicated as a mechanism underpinning memory dysfunction in AD and may result in part from changes in adenosine deaminase acting on RNA (ADAR) mediated RNA editing of the GluA2 subunit of AMPA receptors and changes in AMPA receptor function at the post synaptic cleft. However, few studies have investigated changes in proteins which influence RNA editing and notably, AD studies that focus on studying changes in protein expression, rather than changes in mRNA, often use traditional western blotting. Methods Here, we demonstrate the value of automated capillary western blotting to investigate the protein expression of AMPA receptor subunits (GluA1-4), the ADAR RNA editing proteins (ADAR1-3), and proteins known to regulate RNA editing (PIN1, WWP2, FXR1P, and CREB1), in the J20 AD mouse model. We describe extensive optimisation and validation of the automated capillary western blotting method, demonstrating the use of total protein to normalise protein load, in addition to characterising the optimal protein/antibody concentrations to ensure accurate protein quantification. Following this, we assessed changes in proteins of interest in the hippocampus of 44-week-old J20 AD mice. Results We observed an increase in the expression of ADAR1 p110 and GluA3 and a decrease in ADAR2 in the hippocampus of 44-week-old J20 mice. These changes signify a shift in the balance of proteins that play a critical role at the synapse. Regression analysis revealed unique J20-specific correlations between changes in AMPA receptor subunits, ADAR enzymes, and proteins that regulate ADAR stability in J20 mice, highlighting potential mechanisms mediating RNA-editing changes found in AD. Discussion Our findings in J20 mice generally reflect changes seen in the human AD brain. This study underlines the importance of novel techniques, like automated capillary western blotting, to assess protein expression in AD. It also provides further evidence to support the hypothesis that a dysregulation in RNA editing-related proteins may play a role in the initiation and/or progression of AD.
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Affiliation(s)
- Luke T. Milham
- Centre for Neuroscience and Regenerative Medicine, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Gary P. Morris
- Centre for Neuroscience and Regenerative Medicine, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, NSW, Australia
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, TAS, Australia
| | - Lyndsey M. Konen
- Centre for Neuroscience and Regenerative Medicine, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, NSW, Australia
| | - Peggy Rentsch
- Centre for Neuroscience and Regenerative Medicine, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Nesli Avgan
- Centre for Neuroscience and Regenerative Medicine, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, NSW, Australia
| | - Bryce Vissel
- Centre for Neuroscience and Regenerative Medicine, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, NSW, Australia
- St Vincent’s Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
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Brosens N, Simon C, Kessels HW, Lucassen PJ, Krugers HJ. Early life stress lastingly alters the function and AMPA-receptor composition of glutamatergic synapses in the hippocampus of male mice. J Neuroendocrinol 2023; 35:e13346. [PMID: 37901923 DOI: 10.1111/jne.13346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 08/15/2023] [Accepted: 08/28/2023] [Indexed: 10/31/2023]
Abstract
Early postnatal life is a sensitive period of development that shapes brain structure and function later in life. Exposure to stress during this critical time window can alter brain development and may enhance the susceptibility to psychopathology and neurodegenerative disorders later in life. The developmental effects of early life stress (ELS) on synaptic function are not fully understood, but could provide mechanistic insights into how ELS modifies later brain function and disease risk. We here assessed the effects of ELS on synaptic function and composition in the hippocampus of male mice. Mice were subjected to ELS by housing dams and pups with limited bedding and nesting material from postnatal days (P) 2-9. Synaptic strength was measured in terms of miniature excitatory postsynaptic currents (mEPSCs) in the hippocampal dentate gyrus at three different developmental stages: the early postnatal phase (P9), preadolescence (P21, at weaning) and adulthood at 3 months of age (3MO). Hippocampal synaptosome fractions were isolated from P9 and 3MO tissue and analyzed for protein content to assess postsynaptic composition. Finally, dendritic spine density was assessed in the DG at 3MO. At P9, ELS increased mEPSC frequency and amplitude. In parallel, synaptic composition was altered as PSD-95, GluA3 and GluN2B content were significantly decreased. The increased mEPSC frequency was sustained up to 3MO, at which age, GluA3 content was significantly increased. No differences were found in dendritic spine density. These findings highlight how ELS affects the development of hippocampal synapses, which could provide valuable insight into mechanisms how ELS alters brain function later in life.
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Affiliation(s)
- Niek Brosens
- SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands
| | - Carla Simon
- SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Paul J Lucassen
- SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands
| | - Harm J Krugers
- SILS-CNS, University of Amsterdam, Amsterdam, The Netherlands
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Eltokhi A, Bertocchi I, Rozov A, Jensen V, Borchardt T, Taylor A, Proenca CC, Rawlins JNP, Bannerman DM, Sprengel R. Distinct effects of AMPAR subunit depletion on spatial memory. iScience 2023; 26:108116. [PMID: 37876813 PMCID: PMC10590979 DOI: 10.1016/j.isci.2023.108116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 07/01/2023] [Accepted: 09/29/2023] [Indexed: 10/26/2023] Open
Abstract
Pharmacological studies established a role for AMPARs in the mammalian forebrain in spatial memory performance. Here we generated global GluA1/3 double knockout mice (Gria1/3-/-) and conditional knockouts lacking GluA1 and GluA3 AMPAR subunits specifically from principal cells across the forebrain (Gria1/3ΔFb). In both models, loss of GluA1 and GluA3 resulted in reduced hippocampal GluA2 and increased levels of the NMDAR subunit GluN2A. Electrically-evoked AMPAR-mediated EPSPs were greatly diminished, and there was an absence of tetanus-induced LTP. Gria1/3-/- mice showed premature mortality. Gria1/3ΔFb mice were viable, and their memory performance could be analyzed. In the Morris water maze (MWM), Gria1/3ΔFb mice showed profound long-term memory deficits, in marked contrast to the normal MWM learning previously seen in single Gria1-/- and Gria3-/- knockout mice. Our results suggest a redundancy of function within the pool of available ionotropic glutamate receptors for long-term spatial memory performance.
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Affiliation(s)
- Ahmed Eltokhi
- Departments of Molecular Neurobiology and Physiology, Max Planck Institute for Medical Research, Heidelberg, Germany
- Department of Pharmacolog, University of Washington, Seattle, WA, USA
| | - Ilaria Bertocchi
- Departments of Molecular Neurobiology and Physiology, Max Planck Institute for Medical Research, Heidelberg, Germany
- Department of Neuroscience Rita Levi Montalcini, University of Turin, 10126 Turin, Italy
- Neuroscience Institute - Cavalieri-Ottolenghi Foundation (NICO), Laboratory of Neuropsychopharmacology, Regione Gonzole 10, Orbassano, 10043 Torino, Italy
| | - Andrei Rozov
- Departments of Molecular Neurobiology and Physiology, Max Planck Institute for Medical Research, Heidelberg, Germany
- Institute of Neuroscience, Lobachevsky State University of Nizhniy, 603022 Novgorod, Russia
- Federal Center of Brain Research and Neurotechnology, 117997 Moscow, Russia
| | - Vidar Jensen
- Department of Molecular Medicine, Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, 0372 Oslo, Norway
| | - Thilo Borchardt
- Departments of Molecular Neurobiology and Physiology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Amy Taylor
- Department of Experimental Psychology, University of Oxford, Oxford, UK
| | - Catia C. Proenca
- Departments of Molecular Neurobiology and Physiology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | | | | | - Rolf Sprengel
- Departments of Molecular Neurobiology and Physiology, Max Planck Institute for Medical Research, Heidelberg, Germany
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Santarriaga S, Gerlovin K, Layadi Y, Karmacharya R. Human stem cell-based models to study synaptic dysfunction and cognition in schizophrenia: A narrative review. Schizophr Res 2023:S0920-9964(23)00084-1. [PMID: 36925354 PMCID: PMC10500041 DOI: 10.1016/j.schres.2023.02.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 03/18/2023]
Abstract
Cognitive impairment is the strongest predictor of functional outcomes in schizophrenia and is hypothesized to result from synaptic dysfunction. However, targeting synaptic plasticity and cognitive deficits in patients remains a significant clinical challenge. A comprehensive understanding of synaptic plasticity and the molecular basis of learning and memory in a disease context can provide specific targets for the development of novel therapeutics targeting cognitive impairments in schizophrenia. Here, we describe the role of synaptic plasticity in cognition, summarize evidence for synaptic dysfunction in schizophrenia and demonstrate the use of patient derived induced-pluripotent stem cells for studying synaptic plasticity in vitro. Lastly, we discuss current advances and future technologies for bridging basic science research of synaptic dysfunction with clinical and translational research that can be used to predict treatment response and develop novel therapeutics.
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Affiliation(s)
- Stephanie Santarriaga
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA; Chemical Biology and Therapeutic Science Program, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Kaia Gerlovin
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA; Chemical Biology and Therapeutic Science Program, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Yasmine Layadi
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA; Chimie ParisTech, Université Paris Sciences et Lettres, Paris, France
| | - Rakesh Karmacharya
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA, USA; Chemical Biology and Therapeutic Science Program, Broad Institute of MIT and Harvard, Cambridge, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA; Schizophrenia and Bipolar Disorder Program, McLean Hospital, Belmont, MA, USA.
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Sun Y, Zhang L, Liu P, Peng G. Autoimmunity and Frontotemporal Lobar Degeneration: From Laboratory Study to Clinical Practice. Clin Interv Aging 2023; 18:495-503. [PMID: 37008802 PMCID: PMC10065017 DOI: 10.2147/cia.s394286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 03/16/2023] [Indexed: 03/29/2023] Open
Abstract
Frontotemporal lobar degeneration (FTLD) is a group of neurodegenerative diseases with heterogenous clinical, genetic, and pathological characteristics that show similar impairment of areas in the frontal and/or temporal lobes. Prime doctors' lack of awareness of this complex disease makes early identification and accurate intervention difficult. Autoimmune diseases and autoantibodies are manifestations of different levels of autoimmune reactions. This review presents research findings examining the relationship between autoimmunity and FTLD in terms of autoimmune diseases and autoantibodies with a focus on identifying potential diagnosis and treatment approaches. The findings indicate that the same or similar pathophysiological mechanisms may exist from clinical, genetic, and pathological perspectives. However, the existing evidence is not sufficient to extract substantial conclusions. On the basis of the current situation, we propose future research patterns using prospective studies on large populations and combined clinical and experimental research. Autoimmune reactions or, more generally, inflammatory reactions should receive increased attention from doctors and scientists of all disciplines.
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Affiliation(s)
- Yan Sun
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
| | - Lumi Zhang
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
| | - Ping Liu
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
| | - Guoping Peng
- Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China
- Correspondence: Guoping Peng, Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, #79 Qingchun Road, Hangzhou, Zhejiang Province, 310003, People’s Republic of China, Tel +86 13588150613, Email
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Neurodevelopmental Disorders Associated with PSD-95 and Its Interaction Partners. Int J Mol Sci 2022; 23:ijms23084390. [PMID: 35457207 PMCID: PMC9025546 DOI: 10.3390/ijms23084390] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/13/2022] [Accepted: 04/14/2022] [Indexed: 01/17/2023] Open
Abstract
The postsynaptic density (PSD) is a massive protein complex, critical for synaptic strength and plasticity in excitatory neurons. Here, the scaffolding protein PSD-95 plays a crucial role as it organizes key PSD components essential for synaptic signaling, development, and survival. Recently, variants in DLG4 encoding PSD-95 were found to cause a neurodevelopmental disorder with a variety of clinical features including intellectual disability, developmental delay, and epilepsy. Genetic variants in several of the interaction partners of PSD-95 are associated with similar phenotypes, suggesting that deficient PSD-95 may affect the interaction partners, explaining the overlapping symptoms. Here, we review the transmembrane interaction partners of PSD-95 and their association with neurodevelopmental disorders. We assess how the structural changes induced by DLG4 missense variants may disrupt or alter such protein-protein interactions, and we argue that the pathological effect of DLG4 variants is, at least partly, exerted indirectly through interaction partners of PSD-95. This review presents a direction for functional studies to elucidate the pathogenic mechanism of deficient PSD-95, providing clues for therapeutic strategies.
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