1
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Jenks KR, Cai Y, Nayan ME, Tsimring K, Li K, Zepeda JC, Heller GR, Delepine C, Shih J, Yuan S, Zhu Y, Wang Y, Duan Y, Fu AKY, Ku T, Yun DH, Chung K, Zhang C, Boyden ES, Mellios N, Sur M, Kan Ip JP. The noncoding circular RNA circHomer1 regulates developmental experience-dependent plasticity in mouse visual cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.19.603416. [PMID: 39091722 PMCID: PMC11291094 DOI: 10.1101/2024.07.19.603416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Circular RNAs (circRNAs) are noncoding RNAs abundant in brain tissue, and many are derived from activity-dependent, linear mRNAs encoding for synaptic proteins, suggesting that circRNAs may directly or indirectly play a role in regulating synaptic development, plasticity, and function. However, it is unclear if the circular forms of these RNAs are similarly regulated by activity and what role these circRNAs play in developmental plasticity. Here, we employed transcriptome-wide analysis comparing differential expression of both mRNAs and circRNAs in juvenile mouse primary visual cortex (V1) following monocular deprivation (MD), a model of developmental plasticity. Among the differentially expressed mRNAs and circRNAs following 3-day MD, the circular and the activity-dependent linear forms of the Homer1 gene, circHomer1 and Homer1a respectively, were of interest as their expression changed in opposite directions: circHomer1 expression increased while the expression of Homer1a decreased following MD. Knockdown of circHomer1 prevented the depression of closed-eye responses normally observed after 3-day MD. circHomer1-knockdown led to a reduction in average dendritic spine size prior to MD, but critically there was no further reduction after 3-day MD, consistent with impaired structural plasticity. circHomer1-knockdown also prevented the reduction of surface AMPA receptors after 3-day MD. Synapse-localized puncta of the AMPA receptor endocytic protein Arc increased in volume after MD but were smaller in circHomer1-knockdown neurons, suggesting that circHomer1 regulates plasticity through mechanisms of activity-dependent AMPA receptor endocytosis. Thus, activity-dependent circRNAs regulate developmental synaptic plasticity, and our findings highlight the essential role of circHomer1 in V1 plasticity induced by short-term MD.
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Affiliation(s)
- Kyle R. Jenks
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Ying Cai
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Marvin Eduarte Nayan
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
- Gerald Choa Neuroscience Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Katya Tsimring
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Keji Li
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - José C. Zepeda
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Gregg R. Heller
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Chloe Delepine
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Jennifer Shih
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Shiyang Yuan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Yao Zhu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Ye Wang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yangyang Duan
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Amy K. Y. Fu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Taeyun Ku
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea
| | - Dae Hee Yun
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Kwanghun Chung
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Chi Zhang
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Edward S. Boyden
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
- Howard Hughes Medical Institute, Cambridge, Massachusetts, 02139, USA
| | - Nikolaos Mellios
- Circular Genomics Inc, Albuquerque, New Mexico, 87110, USA
- Previously at: University of New Mexico, Department of Neurosciences, Albuquerque, New Mexico, 87131, USA
| | - Mriganka Sur
- Department of Brain and Cognitive Sciences, The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Jacque Pak Kan Ip
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Gerald Choa Neuroscience Institute, The Chinese University of Hong Kong, Hong Kong, China
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2
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Mesik L, Parkins S, Severin D, Grier BD, Ewall G, Kotha S, Wesselborg C, Moreno C, Jaoui Y, Felder A, Huang B, Johnson MB, Harrigan TP, Knight AE, Lani SW, Lemaire T, Kirkwood A, Hwang GM, Lee HK. Transcranial Low-Intensity Focused Ultrasound Stimulation of the Visual Thalamus Produces Long-Term Depression of Thalamocortical Synapses in the Adult Visual Cortex. J Neurosci 2024; 44:e0784232024. [PMID: 38316559 PMCID: PMC10941064 DOI: 10.1523/jneurosci.0784-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 12/13/2023] [Accepted: 01/30/2024] [Indexed: 02/07/2024] Open
Abstract
Transcranial focused ultrasound stimulation (tFUS) is a noninvasive neuromodulation technique, which can penetrate deeper and modulate neural activity with a greater spatial resolution (on the order of millimeters) than currently available noninvasive brain stimulation methods, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). While there are several studies demonstrating the ability of tFUS to modulate neuronal activity, it is unclear whether it can be used for producing long-term plasticity as needed to modify circuit function, especially in adult brain circuits with limited plasticity such as the thalamocortical synapses. Here we demonstrate that transcranial low-intensity focused ultrasound (LIFU) stimulation of the visual thalamus (dorsal lateral geniculate nucleus, dLGN), a deep brain structure, leads to NMDA receptor (NMDAR)-dependent long-term depression of its synaptic transmission onto layer 4 neurons in the primary visual cortex (V1) of adult mice of both sexes. This change is not accompanied by large increases in neuronal activity, as visualized using the cFos Targeted Recombination in Active Populations (cFosTRAP2) mouse line, or activation of microglia, which was assessed with IBA-1 staining. Using a model (SONIC) based on the neuronal intramembrane cavitation excitation (NICE) theory of ultrasound neuromodulation, we find that the predicted activity pattern of dLGN neurons upon sonication is state-dependent with a range of activity that falls within the parameter space conducive for inducing long-term synaptic depression. Our results suggest that noninvasive transcranial LIFU stimulation has a potential for recovering long-term plasticity of thalamocortical synapses in the postcritical period adult brain.
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Affiliation(s)
- Lukas Mesik
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Samuel Parkins
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Cell Molecular Developmental Biology and Biophysics Graduate Program, Johns Hopkins University, Baltimore, Maryland 21218
| | - Daniel Severin
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
| | - Bryce D Grier
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Gabrielle Ewall
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Sumasri Kotha
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
| | - Christian Wesselborg
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Cell Molecular Developmental Biology and Biophysics Graduate Program, Johns Hopkins University, Baltimore, Maryland 21218
| | - Cristian Moreno
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
| | - Yanis Jaoui
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
| | - Adrianna Felder
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
| | - Brian Huang
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
| | - Marina B Johnson
- Johns Hopkins Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland 20723
| | - Timothy P Harrigan
- Johns Hopkins Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland 20723
| | - Anna E Knight
- Johns Hopkins Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland 20723
| | - Shane W Lani
- Johns Hopkins Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland 20723
| | - Théo Lemaire
- Neuroscience Institute, New York University Langone Health, New York, New York 10016
| | - Alfredo Kirkwood
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
| | - Grace M Hwang
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Johns Hopkins Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland 20723
| | - Hey-Kyoung Lee
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, Maryland 21205
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3
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Huang Z. Evidence that Alzheimer's Disease Is a Disease of Competitive Synaptic Plasticity Gone Awry. J Alzheimers Dis 2024; 99:447-470. [PMID: 38669548 PMCID: PMC11119021 DOI: 10.3233/jad-240042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
Mounting evidence indicates that a physiological function of amyloid-β (Aβ) is to mediate neural activity-dependent homeostatic and competitive synaptic plasticity in the brain. I have previously summarized the lines of evidence supporting this hypothesis and highlighted the similarities between Aβ and anti-microbial peptides in mediating cell/synapse competition. In cell competition, anti-microbial peptides deploy a multitude of mechanisms to ensure both self-protection and competitor elimination. Here I review recent studies showing that similar mechanisms are at play in Aβ-mediated synapse competition and perturbations in these mechanisms underpin Alzheimer's disease (AD). Specifically, I discuss evidence that Aβ and ApoE, two crucial players in AD, co-operate in the regulation of synapse competition. Glial ApoE promotes self-protection by increasing the production of trophic monomeric Aβ and inhibiting its assembly into toxic oligomers. Conversely, Aβ oligomers, once assembled, promote the elimination of competitor synapses via direct toxic activity and amplification of "eat-me" signals promoting the elimination of weak synapses. I further summarize evidence that neuronal ApoE may be part of a gene regulatory network that normally promotes competitive plasticity, explaining the selective vulnerability of ApoE expressing neurons in AD brains. Lastly, I discuss evidence that sleep may be key to Aβ-orchestrated plasticity, in which sleep is not only induced by Aβ but is also required for Aβ-mediated plasticity, underlining the link between sleep and AD. Together, these results strongly argue that AD is a disease of competitive synaptic plasticity gone awry, a novel perspective that may promote AD research.
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Affiliation(s)
- Zhen Huang
- Departments of Neuroscience and Neurology, University of Wisconsin-Madison, Madison, WI, USA
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4
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Radulescu CI, Doostdar N, Zabouri N, Melgosa-Ecenarro L, Wang X, Sadeh S, Pavlidi P, Airey J, Kopanitsa M, Clopath C, Barnes SJ. Age-related dysregulation of homeostatic control in neuronal microcircuits. Nat Neurosci 2023; 26:2158-2170. [PMID: 37919424 PMCID: PMC10689243 DOI: 10.1038/s41593-023-01451-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 09/06/2023] [Indexed: 11/04/2023]
Abstract
Neuronal homeostasis prevents hyperactivity and hypoactivity. Age-related hyperactivity suggests homeostasis may be dysregulated in later life. However, plasticity mechanisms preventing age-related hyperactivity and their efficacy in later life are unclear. We identify the adult cortical plasticity response to elevated activity driven by sensory overstimulation, then test how plasticity changes with age. We use in vivo two-photon imaging of calcium-mediated cellular/synaptic activity, electrophysiology and c-Fos-activity tagging to show control of neuronal activity is dysregulated in the visual cortex in late adulthood. Specifically, in young adult cortex, mGluR5-dependent population-wide excitatory synaptic weakening and inhibitory synaptogenesis reduce cortical activity following overstimulation. In later life, these mechanisms are downregulated, so that overstimulation results in synaptic strengthening and elevated activity. We also find overstimulation disrupts cognition in older but not younger animals. We propose that specific plasticity mechanisms fail in later life dysregulating neuronal microcircuit homeostasis and that the age-related response to overstimulation can impact cognitive performance.
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Affiliation(s)
- Carola I Radulescu
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Nazanin Doostdar
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Nawal Zabouri
- Department of Biomedical Engineering, Imperial College London, South Kensington Campus, London, UK
| | - Leire Melgosa-Ecenarro
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Xingjian Wang
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Sadra Sadeh
- Department of Biomedical Engineering, Imperial College London, South Kensington Campus, London, UK
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Pavlina Pavlidi
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
- Department of Pharmacology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Joe Airey
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
| | | | - Claudia Clopath
- Department of Biomedical Engineering, Imperial College London, South Kensington Campus, London, UK
| | - Samuel J Barnes
- UK Dementia Research Institute, Department of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK.
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5
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Dysregulated Signaling at Postsynaptic Density: A Systematic Review and Translational Appraisal for the Pathophysiology, Clinics, and Antipsychotics' Treatment of Schizophrenia. Cells 2023; 12:cells12040574. [PMID: 36831241 PMCID: PMC9954794 DOI: 10.3390/cells12040574] [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: 11/30/2022] [Revised: 02/07/2023] [Accepted: 02/08/2023] [Indexed: 02/12/2023] Open
Abstract
Emerging evidence from genomics, post-mortem, and preclinical studies point to a potential dysregulation of molecular signaling at postsynaptic density (PSD) in schizophrenia pathophysiology. The PSD that identifies the archetypal asymmetric synapse is a structure of approximately 300 nm in diameter, localized behind the neuronal membrane in the glutamatergic synapse, and constituted by more than 1000 proteins, including receptors, adaptors, kinases, and scaffold proteins. Furthermore, using FASS (fluorescence-activated synaptosome sorting) techniques, glutamatergic synaptosomes were isolated at around 70 nm, where the receptors anchored to the PSD proteins can diffuse laterally along the PSD and were stabilized by scaffold proteins in nanodomains of 50-80 nm at a distance of 20-40 nm creating "nanocolumns" within the synaptic button. In this context, PSD was envisioned as a multimodal hub integrating multiple signaling-related intracellular functions. Dysfunctions of glutamate signaling have been postulated in schizophrenia, starting from the glutamate receptor's interaction with scaffolding proteins involved in the N-methyl-D-aspartate receptor (NMDAR). Despite the emerging role of PSD proteins in behavioral disorders, there is currently no systematic review that integrates preclinical and clinical findings addressing dysregulated PSD signaling and translational implications for antipsychotic treatment in the aberrant postsynaptic function context. Here we reviewed a critical appraisal of the role of dysregulated PSD proteins signaling in the pathophysiology of schizophrenia, discussing how antipsychotics may affect PSD structures and synaptic plasticity in brain regions relevant to psychosis.
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6
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Lee HK. Metaplasticity framework for cross-modal synaptic plasticity in adults. Front Synaptic Neurosci 2023; 14:1087042. [PMID: 36685084 PMCID: PMC9853192 DOI: 10.3389/fnsyn.2022.1087042] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 12/19/2022] [Indexed: 01/09/2023] Open
Abstract
Sensory loss leads to widespread adaptation of neural circuits to mediate cross-modal plasticity, which allows the organism to better utilize the remaining senses to guide behavior. While cross-modal interactions are often thought to engage multisensory areas, cross-modal plasticity is often prominently observed at the level of the primary sensory cortices. One dramatic example is from functional imaging studies in humans where cross-modal recruitment of the deprived primary sensory cortex has been observed during the processing of the spared senses. In addition, loss of a sensory modality can lead to enhancement and refinement of the spared senses, some of which have been attributed to compensatory plasticity of the spared sensory cortices. Cross-modal plasticity is not restricted to early sensory loss but is also observed in adults, which suggests that it engages or enables plasticity mechanisms available in the adult cortical circuit. Because adult cross-modal plasticity is observed without gross anatomical connectivity changes, it is thought to occur mainly through functional plasticity of pre-existing circuits. The underlying cellular and molecular mechanisms involve activity-dependent homeostatic and Hebbian mechanisms. A particularly attractive mechanism is the sliding threshold metaplasticity model because it innately allows neurons to dynamically optimize their feature selectivity. In this mini review, I will summarize the cellular and molecular mechanisms that mediate cross-modal plasticity in the adult primary sensory cortices and evaluate the metaplasticity model as an effective framework to understand the underlying mechanisms.
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7
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Whitt JL, Ewall G, Chakraborty D, Adegbesan A, Lee R, Kanold PO, Lee HK. Visual Deprivation Selectively Reduces Thalamic Reticular Nucleus-Mediated Inhibition of the Auditory Thalamus in Adults. J Neurosci 2022; 42:7921-7930. [PMID: 36261269 PMCID: PMC9617613 DOI: 10.1523/jneurosci.2032-21.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 08/19/2022] [Accepted: 08/24/2022] [Indexed: 11/21/2022] Open
Abstract
Sensory loss leads to widespread cross-modal plasticity across brain areas to allow the remaining senses to guide behavior. While multimodal sensory interactions are often attributed to higher-order sensory areas, cross-modal plasticity has been observed at the level of synaptic changes even across primary sensory cortices. In particular, vision loss leads to widespread circuit adaptation in the primary auditory cortex (A1) even in adults. Here we report using mice of both sexes in which cross-modal plasticity occurs even earlier in the sensory-processing pathway at the level of the thalamus in a modality-selective manner. A week of visual deprivation reduced inhibitory synaptic transmission from the thalamic reticular nucleus (TRN) to the primary auditory thalamus (MGBv) without changes to the primary visual thalamus (dLGN). The plasticity of TRN inhibition to MGBv was observed as a reduction in postsynaptic gain and short-term depression. There was no observable plasticity of the cortical feedback excitatory synaptic transmission from the primary visual cortex to dLGN or TRN and A1 to MGBv, which suggests that the visual deprivation-induced plasticity occurs predominantly at the level of thalamic inhibition. We provide evidence that visual deprivation-induced change in the short-term depression of TRN inhibition to MGBv involves endocannabinoid CB1 receptors. TRN inhibition is considered critical for sensory gating, selective attention, and multimodal performances; hence, its plasticity has implications for sensory processing. Our results suggest that selective disinhibition and altered short-term dynamics of TRN inhibition in the spared thalamic nucleus support cross-modal plasticity in the adult brain.SIGNIFICANCE STATEMENT Losing vision triggers adaptation of the brain to enhance the processing of the remaining senses, which can be observed as better auditory performance in blind subjects. We previously found that depriving vision of adult rodents produces widespread circuit reorganization in the primary auditory cortex and enhances auditory processing at a neural level. Here we report that visual deprivation-induced plasticity in adults occurs much earlier in the auditory pathway, at the level of thalamic inhibition. Sensory processing is largely gated at the level of the thalamus via strong cortical feedback inhibition mediated through the thalamic reticular nucleus (TRN). We found that TRN inhibition of the auditory thalamus is selectively reduced by visual deprivation, thus playing a role in adult cross-modal plasticity.
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Affiliation(s)
- Jessica L Whitt
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Gabrielle Ewall
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Darpan Chakraborty
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Ayorinde Adegbesan
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
| | - Rachel Lee
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
| | - Patrick O Kanold
- Department of Biomedical Engineering, Whiting School of Engineering and Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Hey-Kyoung Lee
- Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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8
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de Bartolomeis A, Barone A, Buonaguro EF, Tomasetti C, Vellucci L, Iasevoli F. The Homer1 family of proteins at the crossroad of dopamine-glutamate signaling: An emerging molecular "Lego" in the pathophysiology of psychiatric disorders. A systematic review and translational insight. Neurosci Biobehav Rev 2022; 136:104596. [PMID: 35248676 DOI: 10.1016/j.neubiorev.2022.104596] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 02/24/2022] [Accepted: 02/27/2022] [Indexed: 12/17/2022]
Abstract
Once considered only scaffolding proteins at glutamatergic postsynaptic density (PSD), Homer1 proteins are increasingly emerging as multimodal adaptors that integrate different signal transduction pathways within PSD, involved in motor and cognitive functions, with putative implications in psychiatric disorders. Regulation of type I metabotropic glutamate receptor trafficking, modulation of calcium signaling, tuning of long-term potentiation, organization of dendritic spines' growth, as well as meta- and homeostatic plasticity control are only a few of the multiple endocellular and synaptic functions that have been linked to Homer1. Findings from preclinical studies, as well as genetic studies conducted in humans, suggest that both constitutive (Homer1b/c) and inducible (Homer1a) isoforms of Homer1 play a role in the neurobiology of several psychiatric disorders, including psychosis, mood disorders, neurodevelopmental disorders, and addiction. On this background, Homer1 has been proposed as a putative novel target in psychopharmacological treatments. The aim of this review is to summarize and systematize the growing body of evidence on Homer proteins, highlighting the role of Homer1 in the pathophysiology and therapy of mental diseases.
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Affiliation(s)
- Andrea de Bartolomeis
- Laboratory of Translational and Molecular Psychiatry and Section of Psychiatry, Department of Neuroscience, University School of Medicine "Federico II", Naples, Italy.
| | - Annarita Barone
- Laboratory of Translational and Molecular Psychiatry and Section of Psychiatry, Department of Neuroscience, University School of Medicine "Federico II", Naples, Italy
| | - Elisabetta Filomena Buonaguro
- Laboratory of Translational and Molecular Psychiatry and Section of Psychiatry, Department of Neuroscience, University School of Medicine "Federico II", Naples, Italy
| | - Carmine Tomasetti
- Laboratory of Translational and Molecular Psychiatry and Section of Psychiatry, Department of Neuroscience, University School of Medicine "Federico II", Naples, Italy
| | - Licia Vellucci
- Laboratory of Translational and Molecular Psychiatry and Section of Psychiatry, Department of Neuroscience, University School of Medicine "Federico II", Naples, Italy
| | - Felice Iasevoli
- Laboratory of Translational and Molecular Psychiatry and Section of Psychiatry, Department of Neuroscience, University School of Medicine "Federico II", Naples, Italy
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9
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Group I Metabotropic Glutamate Receptors and Interacting Partners: An Update. Int J Mol Sci 2022; 23:ijms23020840. [PMID: 35055030 PMCID: PMC8778124 DOI: 10.3390/ijms23020840] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/09/2022] [Accepted: 01/10/2022] [Indexed: 12/21/2022] Open
Abstract
Group I metabotropic glutamate (mGlu) receptors (mGlu1/5 subtypes) are G protein-coupled receptors and are broadly expressed in the mammalian brain. These receptors play key roles in the modulation of normal glutamatergic transmission and synaptic plasticity, and abnormal mGlu1/5 signaling is linked to the pathogenesis and symptomatology of various mental and neurological disorders. Group I mGlu receptors are noticeably regulated via a mechanism involving dynamic protein-protein interactions. Several synaptic protein kinases were recently found to directly bind to the intracellular domains of mGlu1/5 receptors and phosphorylate the receptors at distinct amino acid residues. A variety of scaffolding and adaptor proteins also interact with mGlu1/5. Constitutive or activity-dependent interactions between mGlu1/5 and their interacting partners modulate trafficking, anchoring, and expression of the receptors. The mGlu1/5-associated proteins also finetune the efficacy of mGlu1/5 postreceptor signaling and mGlu1/5-mediated synaptic plasticity. This review analyzes the data from recent studies and provides an update on the biochemical and physiological properties of a set of proteins or molecules that interact with and thus regulate mGlu1/5 receptors.
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10
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Wu XQ, Su N, Fei Z, Fei F. Homer signaling pathways as effective therapeutic targets for ischemic and traumatic brain injuries and retinal lesions. Neural Regen Res 2021; 17:1454-1461. [PMID: 34916418 PMCID: PMC8771115 DOI: 10.4103/1673-5374.330588] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Ischemic and traumatic insults to the central nervous system account for most serious acute and fatal brain injuries and are usually characterized by primary and secondary damage. Secondary damage presents the greatest challenge for medical staff; however, there are currently few effective therapeutic targets for secondary damage. Homer proteins are postsynaptic scaffolding proteins that have been implicated in ischemic and traumatic insults to the central nervous system. Homer signaling can exert either positive or negative effects during such insults, depending on the specific subtype of Homer protein. Homer 1b/c couples with other proteins to form postsynaptic densities, which form the basis of synaptic transmission, while Homer1a expression can be induced by harmful external factors. Homer 1c is used as a unique biomarker to reveal alterations in synaptic connectivity before and during the early stages of apoptosis in retinal ganglion cells, mediated or affected by extracellular or intracellular signaling or cytoskeletal processes. This review summarizes the structural features, related signaling pathways, and diverse roles of Homer proteins in physiological and pathological processes. Upregulating Homer1a or downregulating Homer1b/c may play a neuroprotective role in secondary brain injuries. Homer also plays an important role in the formation of photoreceptor synapses. These findings confirm the neuroprotective effects of Homer, and support the future design of therapeutic drug targets or gene therapies for ischemic and traumatic brain injuries and retinal disorders based on Homer proteins.
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Affiliation(s)
- Xiu-Quan Wu
- Department of Neurosurgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Ning Su
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Zhou Fei
- Department of Neurosurgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Fei Fei
- Department of Ophthalmology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
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11
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Membrane trafficking and positioning of mGluRs at presynaptic and postsynaptic sites of excitatory synapses. Neuropharmacology 2021; 200:108799. [PMID: 34592242 DOI: 10.1016/j.neuropharm.2021.108799] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 08/31/2021] [Accepted: 09/17/2021] [Indexed: 01/21/2023]
Abstract
The plethora of functions of glutamate in the brain are mediated by the complementary actions of ionotropic and metabotropic glutamate receptors (mGluRs). The ionotropic glutamate receptors carry most of the fast excitatory transmission, while mGluRs modulate transmission on longer timescales by triggering multiple intracellular signaling pathways. As such, mGluRs mediate critical aspects of synaptic transmission and plasticity. Interestingly, at synapses, mGluRs operate at both sides of the cleft, and thus bidirectionally exert the effects of glutamate. At postsynaptic sites, group I mGluRs act to modulate excitability and plasticity. At presynaptic sites, group II and III mGluRs act as auto-receptors, modulating release properties in an activity-dependent manner. Thus, synaptic mGluRs are essential signal integrators that functionally couple presynaptic and postsynaptic mechanisms of transmission and plasticity. Understanding how these receptors reach the membrane and are positioned relative to the presynaptic glutamate release site are therefore important aspects of synapse biology. In this review, we will discuss the currently known mechanisms underlying the trafficking and positioning of mGluRs at and around synapses, and how these mechanisms contribute to synaptic functioning. We will highlight outstanding questions and present an outlook on how recent technological developments will move this exciting research field forward.
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12
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Moutin E, Sakkaki S, Compan V, Bouquier N, Giona F, Areias J, Goyet E, Hemonnot-Girard AL, Seube V, Glasson B, Benac N, Chastagnier Y, Raynaud F, Audinat E, Groc L, Maurice T, Sala C, Verpelli C, Perroy J. Restoring glutamate receptosome dynamics at synapses rescues autism-like deficits in Shank3-deficient mice. Mol Psychiatry 2021; 26:7596-7609. [PMID: 34331007 DOI: 10.1038/s41380-021-01230-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 07/02/2021] [Accepted: 07/06/2021] [Indexed: 11/09/2022]
Abstract
Shank3 monogenic mutations lead to autism spectrum disorders (ASD). Shank3 is part of the glutamate receptosome that physically links ionotropic NMDA receptors to metabotropic mGlu5 receptors through interactions with scaffolding proteins PSD95-GKAP-Shank3-Homer. A main physiological function of the glutamate receptosome is to control NMDA synaptic function that is required for plasticity induction. Intact glutamate receptosome supports glutamate receptors activation and plasticity induction, while glutamate receptosome disruption blocks receptors activity, preventing the induction of subsequent plasticity. Despite possible impact on metaplasticity and cognitive behaviors, scaffold interaction dynamics and their consequences are poorly defined. Here, we used mGlu5-Homer interaction as a biosensor of glutamate receptosome integrity to report changes in synapse availability for plasticity induction. Combining BRET imaging and electrophysiology, we show that a transient neuronal depolarization inducing NMDA-dependent plasticity disrupts glutamate receptosome in a long-lasting manner at synapses and activates signaling pathways required for the expression of the initiated neuronal plasticity, such as ERK and mTOR pathways. Glutamate receptosome disruption also decreases the NMDA/AMPA ratio, freezing the sensitivity of the synapse to subsequent changes of neuronal activity. These data show the importance of a fine-tuning of protein-protein interactions within glutamate receptosome, driven by changes of neuronal activity, to control plasticity. In a mouse model of ASD, a truncated mutant form of Shank3 prevents the integrity of the glutamate receptosome. These mice display altered plasticity, anxiety-like, and stereotyped behaviors. Interestingly, repairing the integrity of glutamate receptosome and its sensitivity to the neuronal activity rescued synaptic transmission, plasticity, and some behavioral traits of Shank3∆C mice. Altogether, our findings characterize mechanisms by which Shank3 mutations cause ASD and highlight scaffold dynamics as new therapeutic target.
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Affiliation(s)
- Enora Moutin
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France.
| | - Sophie Sakkaki
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Vincent Compan
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | | | | | - Julie Areias
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Elise Goyet
- Interdisciplinary Institute for NeuroScience, CNRS, UMR 5297, Centre Broca Nouvelle-Aquitaine, 33076, Bordeaux, France
| | | | - Vincent Seube
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Bastien Glasson
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Nathan Benac
- Interdisciplinary Institute for NeuroScience, CNRS, UMR 5297, Centre Broca Nouvelle-Aquitaine, 33076, Bordeaux, France
| | - Yan Chastagnier
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Fabrice Raynaud
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France.,PhyMedExp, Univ Montpellier, INSERM, CNRS, CHU de Montpellier, France
| | - Etienne Audinat
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Laurent Groc
- Interdisciplinary Institute for NeuroScience, CNRS, UMR 5297, Centre Broca Nouvelle-Aquitaine, 33076, Bordeaux, France
| | - Tangui Maurice
- MMDN, Univ Montpellier, EPHE, INSERM, Montpellier, France
| | - Carlo Sala
- Cnr Neuroscience Institute, 3220129, Milan, Italy
| | | | - Julie Perroy
- IGF, University of Montpellier, CNRS, INSERM, Montpellier, France.
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13
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Lin R, Learman LN, Bangash MA, Melnikova T, Leyder E, Reddy SC, Naidoo N, Park JM, Savonenko A, Worley PF. Homer1a regulates Shank3 expression and underlies behavioral vulnerability to stress in a model of Phelan-McDermid syndrome. Cell Rep 2021; 37:110014. [PMID: 34788607 DOI: 10.1016/j.celrep.2021.110014] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/13/2021] [Accepted: 10/26/2021] [Indexed: 11/17/2022] Open
Abstract
Mutations of SHANK3 cause Phelan-McDermid syndrome (PMS), and these individuals can exhibit sensitivity to stress, resulting in behavioral deterioration. Here, we examine the interaction of stress with genotype using a mouse model with face validity to PMS. In Shank3ΔC/+ mice, swim stress produces an altered transcriptomic response in pyramidal neurons that impacts genes and pathways involved in synaptic function, signaling, and protein turnover. Homer1a, which is part of the Shank3-mGluR-N-methyl-D-aspartate (NMDA) receptor complex, is super-induced and is implicated in the stress response because stress-induced social deficits in Shank3ΔC/+ mice are mitigated in Shank3ΔC/+;Homer1a-/- mice. Several lines of evidence demonstrate that Shank3 expression is regulated by Homer1a in competition with crosslinking forms of Homer, and consistent with this model, Shank3 expression and function that are reduced in Shank3ΔC/+ mice are rescued in Shank3ΔC/+;Homer1a-/- mice. Studies highlight the interaction between stress and genetics and focus attention on activity-dependent changes that may contribute to pathogenesis.
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Affiliation(s)
- Raozhou Lin
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Lisa N Learman
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - M Ali Bangash
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA; Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, UK
| | - Tatiana Melnikova
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Erica Leyder
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sai C Reddy
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Nirinjini Naidoo
- Division of Sleep Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Joo Min Park
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Republic of Korea; University of Science and Technology, Daejeon 34113, Republic of Korea.
| | - Alena Savonenko
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Paul F Worley
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA.
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14
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Russ DE, Cross RBP, Li L, Koch SC, Matson KJE, Yadav A, Alkaslasi MR, Lee DI, Le Pichon CE, Menon V, Levine AJ. A harmonized atlas of mouse spinal cord cell types and their spatial organization. Nat Commun 2021; 12:5722. [PMID: 34588430 PMCID: PMC8481483 DOI: 10.1038/s41467-021-25125-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 07/21/2021] [Indexed: 12/12/2022] Open
Abstract
Single-cell RNA sequencing data can unveil the molecular diversity of cell types. Cell type atlases of the mouse spinal cord have been published in recent years but have not been integrated together. Here, we generate an atlas of spinal cell types based on single-cell transcriptomic data, unifying the available datasets into a common reference framework. We report a hierarchical structure of postnatal cell type relationships, with location providing the highest level of organization, then neurotransmitter status, family, and finally, dozens of refined populations. We validate a combinatorial marker code for each neuronal cell type and map their spatial distributions in the adult spinal cord. We also show complex lineage relationships among postnatal cell types. Additionally, we develop an open-source cell type classifier, SeqSeek, to facilitate the standardization of cell type identification. This work provides an integrated view of spinal cell types, their gene expression signatures, and their molecular organization.
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Affiliation(s)
- Daniel E Russ
- Division of Cancer Epidemiology and Genetics, Data Science Research Group, National Cancer Institute, NIH, Rockville, MD, USA
| | - Ryan B Patterson Cross
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Li Li
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Stephanie C Koch
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London, UK
| | - Kaya J E Matson
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Archana Yadav
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA
| | - Mor R Alkaslasi
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA.,Department of Neuroscience, Brown University, Providence, RI, USA
| | - Dylan I Lee
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA
| | - Claire E Le Pichon
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Vilas Menon
- Department of Neurology, Center for Translational and Computational Neuroimmunology, Columbia University, New York, NY, USA
| | - Ariel J Levine
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA.
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15
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Bockaert J, Perroy J, Ango F. The Complex Formed by Group I Metabotropic Glutamate Receptor (mGluR) and Homer1a Plays a Central Role in Metaplasticity and Homeostatic Synaptic Scaling. J Neurosci 2021; 41:5567-5578. [PMID: 34193623 PMCID: PMC8244974 DOI: 10.1523/jneurosci.0026-21.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 05/05/2021] [Accepted: 05/06/2021] [Indexed: 12/28/2022] Open
Abstract
G-protein-coupled receptors can be constitutively activated following physical interaction with intracellular proteins. The first example described was the constitutive activation of Group I metabotropic glutamate receptors (mGluR: mGluR1,5) following their interaction with Homer1a, an activity-inducible early-termination variant of the scaffolding protein Homer that lacks dimerization capacity (Ango et al., 2001). Homer1a disrupts the links, maintained by the long form of Homer (cross-linking Homers), between mGluR1,5 and the Shank-GKAP-PSD-95-ionotropic glutamate receptor network. Two characteristics of the constitutive activation of the Group I mGluR-Homer1a complex are particularly interesting: (1) it affects a large number of synapses in which Homer1a is upregulated following enhanced, long-lasting neuronal activity; and (2) it mainly depends on Homer1a protein turnover. The constitutively active Group I mGluR-Homer1a complex is involved in the two main forms of non-Hebbian neuronal plasticity: "metaplasticity" and "homeostatic synaptic scaling," which are implicated in a large series of physiological and pathologic processes. Those include non-Hebbian plasticity observed in visual system, synapses modulated by addictive drugs (rewarded synapses), chronically overactivated synaptic networks, normal sleep, and sleep deprivation.
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Affiliation(s)
- Joël Bockaert
- Institut de Génomique Fonctionnelle, Université Montpellier, Center National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, 34094 Montpellier, France
| | - Julie Perroy
- Institut de Génomique Fonctionnelle, Université Montpellier, Center National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, 34094 Montpellier, France
| | - Fabrice Ango
- Institut des Neurosciences de Montpellier, Université Montpellier, Center National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, 34295 Montpellier, France
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16
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Gonzalez-Lozano MA, Wortel J, van der Loo RJ, van Weering JRT, Smit AB, Li KW. Reduced mGluR5 Activity Modulates Mitochondrial Function. Cells 2021; 10:cells10061375. [PMID: 34199502 PMCID: PMC8228325 DOI: 10.3390/cells10061375] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/23/2021] [Accepted: 05/31/2021] [Indexed: 11/30/2022] Open
Abstract
The metabotropic glutamate receptor 5 (mGluR5) is an essential modulator of synaptic plasticity, learning and memory; whereas in pathological conditions, it is an acknowledged therapeutic target that has been implicated in multiple brain disorders. Despite robust pre-clinical data, mGluR5 antagonists failed in several clinical trials, highlighting the need for a better understanding of the mechanisms underlying mGluR5 function. In this study, we dissected the molecular synaptic modulation mediated by mGluR5 using genetic and pharmacological mouse models to chronically and acutely reduce mGluR5 activity. We found that next to dysregulation of synaptic proteins, the major regulation in protein expression in both models concerned specific processes in mitochondria, such as oxidative phosphorylation. Second, we observed morphological alterations in shape and area of specifically postsynaptic mitochondria in mGluR5 KO synapses using electron microscopy. Third, computational and biochemical assays suggested an increase of mitochondrial function in neurons, with increased level of NADP/H and oxidative damage in mGluR5 KO. Altogether, our observations provide diverse lines of evidence of the modulation of synaptic mitochondrial function by mGluR5. This connection suggests a role for mGluR5 as a mediator between synaptic activity and mitochondrial function, a finding which might be relevant for the improvement of the clinical potential of mGluR5.
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Affiliation(s)
- Miguel A. Gonzalez-Lozano
- Center for Neurogenomics and Cognitive Research, Department of Molecular and Cellular Neurobiology, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, 1081 Amsterdam, The Netherlands; (R.J.v.d.L.); (A.B.S.)
- Correspondence: (M.A.G.-L.); (K.W.L.)
| | - Joke Wortel
- Center for Neurogenomics and Cognitive Research, Department of Functional Genomics, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, 1081 Amsterdam, The Netherlands; (J.W.); (J.R.T.v.W.)
| | - Rolinka J. van der Loo
- Center for Neurogenomics and Cognitive Research, Department of Molecular and Cellular Neurobiology, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, 1081 Amsterdam, The Netherlands; (R.J.v.d.L.); (A.B.S.)
| | - Jan R. T. van Weering
- Center for Neurogenomics and Cognitive Research, Department of Functional Genomics, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, 1081 Amsterdam, The Netherlands; (J.W.); (J.R.T.v.W.)
- Center for Neurogenomics and Cognitive Research, Department of Clinical Genetics, Amsterdam Neuroscience, Amsterdam UMC location VUmc, 1081 Amsterdam, The Netherlands
| | - August B. Smit
- Center for Neurogenomics and Cognitive Research, Department of Molecular and Cellular Neurobiology, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, 1081 Amsterdam, The Netherlands; (R.J.v.d.L.); (A.B.S.)
| | - Ka Wan Li
- Center for Neurogenomics and Cognitive Research, Department of Molecular and Cellular Neurobiology, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, 1081 Amsterdam, The Netherlands; (R.J.v.d.L.); (A.B.S.)
- Correspondence: (M.A.G.-L.); (K.W.L.)
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17
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Bockaert J, Bécamel C, Chaumont-Dubel S, Claeysen S, Vandermoere F, Marin P. Novel and atypical pathways for serotonin signaling. Fac Rev 2021; 10:52. [PMID: 34195691 PMCID: PMC8204760 DOI: 10.12703/r/10-52] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Serotonin (5-HT) appeared billions of years before 5-HT receptors and synapses. It is thus not surprising that 5-HT can control biological processes independently of its receptors. One example is serotonylation, which consists of covalent binding of 5-HT to the primary amine of glutamine. Over the past 20 years, serotonylation has been involved in the regulation of many signaling mechanisms. One of the most striking examples is the recent evidence that serotonylation of histone H3 constitutes an epigenetic mark. However, the pathophysiological role of histone H3 serotonylation remains to be discovered. All but one of the 5-HT receptors are G-protein-coupled receptors (GPCRs). The signaling pathways they control are finely tuned, and new, unexpected regulatory mechanisms are being uncovered continuously. Some 5-HT receptors (5-HT2C, 5-HT4, 5-HT6, and 5-HT7) signal through mechanisms that require neither G-proteins nor β-arrestins, the two classical and almost universal GPCR signal transducers. 5-HT6 receptors are constitutively activated via their association with intracellular GPCR-interacting proteins (GIPs), including neurofibromin 1, cyclin-dependent kinase 5 (Cdk5), and G-protein-regulated inducer of neurite outgrowth 1 (GPRIN1). Interactions of 5-HT6 receptor with Cdk5 and GPRIN1 are not concomitant but occur sequentially and play a key role in dendritic tree morphogenesis. Furthermore, 5-HT6 receptor-mediated G-protein signaling in neurons is different in the cell body and primary cilium, where it is modulated by smoothened receptor activation. Finally, 5-HT2A receptors form heteromers with mGlu2 metabotropic glutamate receptors. This heteromerization results in a specific phosphorylation of mGlu2 receptor on a serine residue (Ser843) upon agonist stimulation of 5-HT2A or mGlu2 receptor. mGlu2 receptor phosphorylation on Ser843 is an essential step in engagement of Gi/o signaling not only upon mGlu2 receptor activation but also following 5-HT2A receptor activation, and thus represents a key molecular event underlying functional crosstalk between both receptors.
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Affiliation(s)
- Joël Bockaert
- The Institute of Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Carine Bécamel
- The Institute of Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Séverine Chaumont-Dubel
- The Institute of Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Sylvie Claeysen
- The Institute of Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Franck Vandermoere
- The Institute of Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Philippe Marin
- The Institute of Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
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18
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Ewall G, Parkins S, Lin A, Jaoui Y, Lee HK. Cortical and Subcortical Circuits for Cross-Modal Plasticity Induced by Loss of Vision. Front Neural Circuits 2021; 15:665009. [PMID: 34113240 PMCID: PMC8185208 DOI: 10.3389/fncir.2021.665009] [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: 02/06/2021] [Accepted: 04/14/2021] [Indexed: 11/29/2022] Open
Abstract
Cortical areas are highly interconnected both via cortical and subcortical pathways, and primary sensory cortices are not isolated from this general structure. In primary sensory cortical areas, these pre-existing functional connections serve to provide contextual information for sensory processing and can mediate adaptation when a sensory modality is lost. Cross-modal plasticity in broad terms refers to widespread plasticity across the brain in response to losing a sensory modality, and largely involves two distinct changes: cross-modal recruitment and compensatory plasticity. The former involves recruitment of the deprived sensory area, which includes the deprived primary sensory cortex, for processing the remaining senses. Compensatory plasticity refers to plasticity in the remaining sensory areas, including the spared primary sensory cortices, to enhance the processing of its own sensory inputs. Here, we will summarize potential cellular plasticity mechanisms involved in cross-modal recruitment and compensatory plasticity, and review cortical and subcortical circuits to the primary sensory cortices which can mediate cross-modal plasticity upon loss of vision.
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Affiliation(s)
- Gabrielle Ewall
- Solomon H. Snyder Department of Neuroscience, Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Samuel Parkins
- Cell, Molecular, Developmental Biology and Biophysics (CMDB) Graduate Program, Johns Hopkins University, Baltimore, MD, United States
| | - Amy Lin
- Solomon H. Snyder Department of Neuroscience, Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Yanis Jaoui
- Solomon H. Snyder Department of Neuroscience, Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Hey-Kyoung Lee
- Solomon H. Snyder Department of Neuroscience, Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins School of Medicine, Baltimore, MD, United States.,Cell, Molecular, Developmental Biology and Biophysics (CMDB) Graduate Program, Johns Hopkins University, Baltimore, MD, United States.,Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, United States
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19
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Heavner WE, Lautz JD, Speed HE, Gniffke EP, Immendorf KB, Welsh JP, Baertsch NA, Smith SEP. Remodeling of the Homer-Shank interactome mediates homeostatic plasticity. Sci Signal 2021; 14:14/681/eabd7325. [PMID: 33947797 DOI: 10.1126/scisignal.abd7325] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Neurons maintain stable levels of excitability using homeostatic synaptic scaling, which adjusts the strength of a neuron's postsynaptic inputs to compensate for extended changes in overall activity. Here, we investigated whether prolonged changes in activity affect network-level protein interactions at the synapse. We assessed a glutamatergic synapse protein interaction network (PIN) composed of 380 binary associations among 21 protein members in mouse neurons. Manipulating the activation of cultured mouse cortical neurons induced widespread bidirectional PIN alterations that reflected rapid rearrangements of glutamate receptor associations involving synaptic scaffold remodeling. Sensory deprivation of the barrel cortex in live mice (by whisker trimming) caused specific PIN rearrangements, including changes in the association between the glutamate receptor mGluR5 and the kinase Fyn. These observations are consistent with emerging models of experience-dependent plasticity involving multiple types of homeostatic responses. However, mice lacking Homer1 or Shank3B did not undergo normal PIN rearrangements, suggesting that the proteins encoded by these autism spectrum disorder-linked genes serve as structural hubs for synaptic homeostasis. Our approach demonstrates how changes in the protein content of synapses during homeostatic plasticity translate into functional PIN alterations that mediate changes in neuron excitability.
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Affiliation(s)
- Whitney E Heavner
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Jonathan D Lautz
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Haley E Speed
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Edward P Gniffke
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Karen B Immendorf
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - John P Welsh
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA.,Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA.,University of Washington Autism Center, Seattle, WA 98195, USA.,Graduate Program in Neuroscience, University of Washington, Seattle, WA 98195, USA
| | - Nathan A Baertsch
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA.,Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Stephen E P Smith
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA. .,Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98195, USA.,Graduate Program in Neuroscience, University of Washington, Seattle, WA 98195, USA
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20
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Chokshi V, Grier BD, Dykman A, Lantz CL, Niebur E, Quinlan EM, Lee HK. Naturalistic Spike Trains Drive State-Dependent Homeostatic Plasticity in Superficial Layers of Visual Cortex. Front Synaptic Neurosci 2021; 13:663282. [PMID: 33935679 PMCID: PMC8081846 DOI: 10.3389/fnsyn.2021.663282] [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: 02/02/2021] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
The history of neural activity determines the synaptic plasticity mechanisms employed in the brain. Previous studies report a rapid reduction in the strength of excitatory synapses onto layer 2/3 (L2/3) pyramidal neurons of the primary visual cortex (V1) following two days of dark exposure and subsequent re-exposure to light. The abrupt increase in visually driven activity is predicted to drive homeostatic plasticity, however, the parameters of neural activity that trigger these changes are unknown. To determine this, we first recorded spike trains in vivo from V1 layer 4 (L4) of dark exposed (DE) mice of both sexes that were re-exposed to light through homogeneous or patterned visual stimulation. We found that delivering the spike patterns recorded in vivo to L4 of V1 slices was sufficient to reduce the amplitude of miniature excitatory postsynaptic currents (mEPSCs) of V1 L2/3 neurons in DE mice, but not in slices obtained from normal reared (NR) controls. Unexpectedly, the same stimulation pattern produced an up-regulation of mEPSC amplitudes in V1 L2/3 neurons from mice that received 2 h of light re-exposure (LE). A Poisson spike train exhibiting the same average frequency as the patterns recorded in vivo was equally effective at depressing mEPSC amplitudes in L2/3 neurons in V1 slices prepared from DE mice. Collectively, our results suggest that the history of visual experience modifies the responses of V1 neurons to stimulation and that rapid homeostatic depression of excitatory synapses can be driven by non-patterned input activity.
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Affiliation(s)
- Varun Chokshi
- The Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, United States
- Cell Molecular Developmental Biology and Biophysics (CMDB) Graduate Program, Johns Hopkins University, Baltimore, MD, United States
| | - Bryce D. Grier
- The Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, United States
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Andrew Dykman
- The Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, United States
| | - Crystal L. Lantz
- Department of Biology, University of Maryland, College Park, MD, United States
| | - Ernst Niebur
- The Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, United States
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Elizabeth M. Quinlan
- Department of Biology, University of Maryland, College Park, MD, United States
- Neuroscience and Cognitive Science Program, Brain and Behavior Institute, University of Maryland, College Park, MD, United States
| | - Hey-Kyoung Lee
- The Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, United States
- Cell Molecular Developmental Biology and Biophysics (CMDB) Graduate Program, Johns Hopkins University, Baltimore, MD, United States
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, United States
- The Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, United States
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21
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Torrado Pacheco A, Bottorff J, Gao Y, Turrigiano GG. Sleep Promotes Downward Firing Rate Homeostasis. Neuron 2021; 109:530-544.e6. [PMID: 33232655 PMCID: PMC7864886 DOI: 10.1016/j.neuron.2020.11.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 09/15/2020] [Accepted: 10/30/2020] [Indexed: 12/11/2022]
Abstract
Homeostatic plasticity is hypothesized to bidirectionally regulate neuronal activity around a stable set point to compensate for learning-related plasticity, but to date only upward firing rate homeostasis (FRH) has been demonstrated in vivo. We combined chronic electrophysiology in freely behaving animals with an eye-reopening paradigm to enhance firing in primary visual cortex (V1) and found that neurons bidirectionally regulate firing rates around an individual set point. Downward FRH did not require N-methyl-D-aspartate receptor (NMDAR) signaling and was associated with homeostatic scaling down of synaptic strengths. Like upward FRH, downward FRH was gated by arousal state but in the opposite direction: it occurred during sleep, not during wake. In contrast, firing rate depression associated with Hebbian plasticity happened independently of sleep and wake. Thus, sleep and wake states temporally segregate upward and downward FRH, which might prevent interference or provide unopposed homeostatic compensation when it is needed most.
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Affiliation(s)
| | - Juliet Bottorff
- Department of Biology, Brandeis University, Waltham, MA 02453, USA
| | - Ya Gao
- Department of Biology, Brandeis University, Waltham, MA 02453, USA
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22
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The aging mouse brain: cognition, connectivity and calcium. Cell Calcium 2021; 94:102358. [PMID: 33517250 DOI: 10.1016/j.ceca.2021.102358] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/16/2021] [Accepted: 01/18/2021] [Indexed: 02/08/2023]
Abstract
Aging is a complex process that differentially impacts multiple cognitive, sensory, neuronal and molecular processes. Technological innovations now allow for parallel investigation of neuronal circuit function, structure and molecular composition in the brain of awake behaving adult mice. Thus, mice have become a critical tool to better understand how aging impacts the brain. However, a more granular systems-based approach, which considers the impact of age on key features relating to neural processing, is required. Here, we review evidence probing the impact of age on the mouse brain. We focus on a range of processes relating to neuronal function, including cognitive abilities, sensory systems, synaptic plasticity and calcium regulation. Across many systems, we find evidence for prominent age-related dysregulation even before 12 months of age, suggesting that emerging age-related alterations can manifest by late adulthood. However, we also find reports suggesting that some processes are remarkably resilient to aging. The evidence suggests that aging does not drive a parallel, linear dysregulation of all systems, but instead impacts some processes earlier, and more severely, than others. We propose that capturing the more fine-scale emerging features of age-related vulnerability and resilience may provide better opportunities for the rejuvenation of the aged brain.
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23
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Ma N, Zhang W, Wan J. Research Progress on circRNA in Nervous System Diseases. Curr Alzheimer Res 2020; 17:687-697. [DOI: 10.2174/1567205017666201111114928] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 07/10/2020] [Accepted: 07/16/2020] [Indexed: 12/19/2022]
Abstract
Circular RNAs (circRNAs) are a kind of non-coding RNA molecule with highly stable circular
structures. CircRNAs are primarily composed of exons and/or introns. Recently, a lot of exciting
studies showed that circRNA played an essential role in the development of nervous system diseases.
Here, classification, characteristics, biogenesis, and the association of circRNA dysregulation with nervous
system diseases, such as Alzheimer’s disease, are summarized. The review not only contributes to a
better understanding of circRNAs, but also provides new research directions toward the diagnosis, treatment,
and prevention of nervous system diseases.
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Affiliation(s)
- Nana Ma
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University, The Hong Kong University of Science and Technology Medical Center, Shenzhen, Guangdong Province, China
| | - Wei Zhang
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University, The Hong Kong University of Science and Technology Medical Center, Shenzhen, Guangdong Province, China
| | - Jun Wan
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University, The Hong Kong University of Science and Technology Medical Center, Shenzhen, Guangdong Province, China
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24
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Association between human gray matter metabotropic glutamate receptor-5 availability in vivo and white matter properties: a [ 11C]ABP688 PET and diffusion tensor imaging study. Brain Struct Funct 2020; 225:1805-1816. [PMID: 32495131 DOI: 10.1007/s00429-020-02094-7] [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: 12/23/2019] [Accepted: 05/26/2020] [Indexed: 10/24/2022]
Abstract
Excitatory corticofugal projections in the subcortical white matter (WM) convey signals arising from local neuronal activity in the gray matter (GM). We hypothesized that metabotropic glutamate receptor-5 (mGluR5) availability in GM, as a surrogate marker for local glutamatergic neuronal activity, correlates with WM properties in healthy brain. We examined the relationship in healthy individuals between GM mGluR5 availability measured in vivo using [11C]ABP688 positron emission tomography (PET) and WM properties measured as fractional anisotropy (FA) using diffusion tensor imaging (DTI). Twenty-three healthy volunteers underwent this multimodal imaging. We calculated mGluR5 availability, [11C]ABP688 binding potential (BPND), using the simplified reference tissue model, and generated DTI FA maps using FMRIB's Diffusion Toolbox (FDT) along with Tract-Based Spatial Statistics (TBSS). To investigate the relationship between mGluR5 availability and FA, we performed voxel-wise and region of interest (ROI)-based analyses. The voxel-wise analysis showed significant positive correlations between the whole cerebral GM [11C]ABP688 BPND and the FA in widespread WM regions including the corpus callosum body, internal capsule, and corona radiata (FWE corrected p < 0.05). The ROI-based analysis also revealed significant positive correlations (Bonferroni-corrected threshold p < 0.00021) between [11C]ABP688 BPND in the frontal and parietal cortical GM and FA in the internal capsule (anterior limb and retrolenticular part). Using a novel multimodal imaging interrogation, we provide the first evidence that GM mGluR5 availability is significantly positively associated with WM properties in healthy subjects. Future comparison studies could determine whether this relationship is perturbed in neuropsychiatric disorders with dysregulated mGluR5 signaling.
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25
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Heavner WE, Smith SEP. Resolving the Synaptic versus Developmental Dichotomy of Autism Risk Genes. Trends Neurosci 2020; 43:227-241. [PMID: 32209454 DOI: 10.1016/j.tins.2020.01.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/21/2020] [Accepted: 01/30/2020] [Indexed: 12/28/2022]
Abstract
Genes that are mutated in Autism Spectrum Disorders (ASD) can be classified broadly as either synaptic or developmental. But what if this is a false distinction? A recent spate of publications has provided evidence for developmental mechanisms that rely on neural activity for proper cortical development. Conversely, a growing body of evidence indicates a role for developmental mechanisms, particularly chromatin remodeling, during learning or in response to neural activity. Here, we review these recent publications and propose a model in which genes that confer ASD risk operate in signal transduction networks critical for both cortical development and synaptic homeostasis.
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Affiliation(s)
- Whitney E Heavner
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Stephen E P Smith
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, USA; Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA.
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26
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Lee HK, Kirkwood A. Mechanisms of Homeostatic Synaptic Plasticity in vivo. Front Cell Neurosci 2019; 13:520. [PMID: 31849610 PMCID: PMC6901705 DOI: 10.3389/fncel.2019.00520] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 11/06/2019] [Indexed: 11/13/2022] Open
Abstract
Synapses undergo rapid activity-dependent plasticity to store information, which when left uncompensated can lead to destabilization of neural function. It has been well documented that homeostatic changes, which operate at a slower time scale, are required to maintain stability of neural networks. While there are many mechanisms that can endow homeostatic control, sliding threshold and synaptic scaling are unique in that they operate by providing homeostatic control of synaptic strength. The former mechanism operates by adjusting the threshold for synaptic plasticity, while the latter mechanism directly alters the gain of synapses. Both modes of homeostatic synaptic plasticity have been studied across various preparations from reduced in vitro systems, such as neuronal cultures, to in vivo intact circuitry. While most of the cellular and molecular mechanisms of homeostatic synaptic plasticity have been worked out using reduced preparations, there are unique challenges present in intact circuitry in vivo, which deserve further consideration. For example, in an intact circuit, neurons receive distinct set of inputs across their dendritic tree which carry unique information. Homeostatic synaptic plasticity in vivo needs to operate without compromising processing of these distinct set of inputs to preserve information processing while maintaining network stability. In this mini review, we will summarize unique features of in vivo homeostatic synaptic plasticity, and discuss how sliding threshold and synaptic scaling may act across different activity regimes to provide homeostasis.
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Affiliation(s)
- Hey-Kyoung Lee
- Department of Neuroscience, Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, United States.,Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, United States
| | - Alfredo Kirkwood
- Department of Neuroscience, Mind/Brain Institute, Johns Hopkins University, Baltimore, MD, United States
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