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Sun M, Zheng Q, Wang L, Wang R, Cui H, Zhang X, Xu C, Yin F, Yan H, Qiao X. Alcohol Consumption During Adolescence Alters the Cognitive Function in Adult Male Mice by Persistently Increasing Levels of DUSP6. Mol Neurobiol 2024; 61:3161-3178. [PMID: 37978157 DOI: 10.1007/s12035-023-03794-x] [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: 04/20/2023] [Accepted: 11/01/2023] [Indexed: 11/19/2023]
Abstract
Binge alcohol drinking during adolescence has long-term effects on the adult brain that alter brain structure and behaviors, but the underlying mechanisms remain poorly understood. Extracellular signal-regulated kinase (ERK) is involved in the synaptic plasticity and pathological brain injury by regulating the expression of cyclic adenosine monophosphate response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF). Dual-specificity phosphatase 6 (DUSP6) is a critical effector that dephosphorylates ERK1/2 to control the basal tone, amplitude, and duration of ERK signaling. To explore DUSP6 as a regulator of ERK signaling in the mPFC and its impact on long-term effects of alcohol, a male mouse model of adolescent intermittent alcohol (AIA) exposure was established. Behavioral experiments showed that AIA did not affect anxiety-like behavior or sociability in adulthood, but significantly damaged new object recognition and social recognition memory. Molecular studies further found that AIA reduced the levels of pERK-pCREB-BDNF-PSD95/NR2A involved in synaptic plasticity, while DUSP6 was significantly increased. Intra-mPFC infusion of AAV-DUSP6-shRNA restored the dendritic spine density and postsynaptic density thickness by reversing the level of p-ERK and its downstream molecular expression, and ultimately repaired adult cognitive impairment caused by chronic alcohol exposure during adolescence. These findings indicate that AIA exposure inhibits ERK-CREB-BDNF-PSD95/NR2A by increasing DUSP6 in the mPFC in adulthood that may be associated with long-lasting cognitive deficits.
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Affiliation(s)
- Mizhu Sun
- Department of Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, No.100, Science Avenue, Zhengzhou, 450001, Henan, China
| | - Qingmeng Zheng
- Department of Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, No.100, Science Avenue, Zhengzhou, 450001, Henan, China
| | - Lulu Wang
- Department of Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, No.100, Science Avenue, Zhengzhou, 450001, Henan, China
| | - Runzhi Wang
- Department of Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, No.100, Science Avenue, Zhengzhou, 450001, Henan, China
| | - Hengzhen Cui
- Basic Medicine, School of Medicine, Zhengzhou University, No.100, Science Avenue, Zhengzhou, 450001, Henan, China
| | - Xinlei Zhang
- Department of Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, No.100, Science Avenue, Zhengzhou, 450001, Henan, China
| | - Chen Xu
- Department of Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, No.100, Science Avenue, Zhengzhou, 450001, Henan, China
| | - Fangyuan Yin
- College of Forensic Science, School of Medicine, Xi'an Jiaotong University, No. 76, Yanta West Road, Xi'an, 710061, Shaanxi, China
| | - Hongtao Yan
- Department of Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, No.100, Science Avenue, Zhengzhou, 450001, Henan, China
| | - Xiaomeng Qiao
- Department of Forensic Medicine, School of Basic Medical Sciences, Zhengzhou University, No.100, Science Avenue, Zhengzhou, 450001, Henan, China.
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2
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Wu H, Chen X, Shen Z, Li H, Liang S, Lu Y, Zhang M. Phosphorylation-dependent membraneless organelle fusion and fission illustrated by postsynaptic density assemblies. Mol Cell 2024; 84:309-326.e7. [PMID: 38096828 DOI: 10.1016/j.molcel.2023.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 09/10/2023] [Accepted: 11/13/2023] [Indexed: 01/21/2024]
Abstract
Membraneless organelles formed by phase separation of proteins and nucleic acids play diverse cellular functions. Whether and, if yes, how membraneless organelles in ways analogous to membrane-based organelles also undergo regulated fusion and fission is unknown. Here, using a partially reconstituted mammalian postsynaptic density (PSD) condensate as a paradigm, we show that membraneless organelles can undergo phosphorylation-dependent fusion and fission. Without phosphorylation of the SAPAP guanylate kinase domain-binding repeats, the upper and lower layers of PSD protein mixtures form two immiscible sub-compartments in a phase-in-phase organization. Phosphorylation of SAPAP leads to fusion of the two sub-compartments into one condensate accompanied with an increased Stargazin density in the condensate. Dephosphorylation of SAPAP can reverse this event. Preventing SAPAP phosphorylation in vivo leads to increased separation of proteins from the lower and upper layers of PSD sub-compartments. Thus, analogous to membrane-based organelles, membraneless organelles can also undergo regulated fusion and fission.
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Affiliation(s)
- Haowei Wu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xudong Chen
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Zeyu Shen
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Hao Li
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Shiqi Liang
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Youming Lu
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Mingjie Zhang
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518036, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
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Tao-Cheng JH, Moreira SL, Winters CA, Reese TS, Dosemeci A. Modification of the synaptic cleft under excitatory conditions. Front Synaptic Neurosci 2023; 15:1239098. [PMID: 37840571 PMCID: PMC10568020 DOI: 10.3389/fnsyn.2023.1239098] [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: 06/12/2023] [Accepted: 09/14/2023] [Indexed: 10/17/2023] Open
Abstract
The synaptic cleft is the extracellular part of the synapse, bridging the pre- and postsynaptic membranes. The geometry and molecular organization of the cleft is gaining increased attention as an important determinant of synaptic efficacy. The present study by electron microscopy focuses on short-term morphological changes at the synaptic cleft under excitatory conditions. Depolarization of cultured hippocampal neurons with high K+ results in an increased frequency of synaptic profiles with clefts widened at the periphery (open clefts), typically exhibiting patches of membranes lined by postsynaptic density, but lacking associated presynaptic membranes (18.0% open clefts in high K+ compared to 1.8% in controls). Similarly, higher frequencies of open clefts were observed in adult brain upon a delay of perfusion fixation to promote excitatory/ischemic conditions. Inhibition of basal activity in cultured neurons through the application of TTX results in the disappearance of open clefts whereas application of NMDA increases their frequency (19.0% in NMDA vs. 5.3% in control and 2.6% in APV). Depletion of extracellular Ca2+ with EGTA also promotes an increase in the frequency of open clefts (16.6% in EGTA vs. 4.0% in controls), comparable to that by depolarization or NMDA, implicating dissociation of Ca2+-dependent trans-synaptic bridges. Dissociation of transsynaptic bridges under excitatory conditions may allow perisynaptic mobile elements, such as AMPA receptors to enter the cleft. In addition, peripheral opening of the cleft would facilitate neurotransmitter clearance and thus may have a homeostatic and/or protective function.
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Affiliation(s)
- Jung-Hwa Tao-Cheng
- NINDS Electron Microscopy Facility, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Sandra L. Moreira
- NINDS Electron Microscopy Facility, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Christine A. Winters
- Laboratory of Neurobiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Thomas S. Reese
- Laboratory of Neurobiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Ayse Dosemeci
- Laboratory of Neurobiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
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Lawrence JA, Aguilar-Calvo P, Ojeda-Juárez D, Khuu H, Soldau K, Pizzo DP, Wang J, Malik A, Shay TF, Sullivan EE, Aulston B, Song SM, Callender JA, Sanchez H, Geschwind MD, Roy S, Rissman RA, Trejo J, Tanaka N, Wu C, Chen X, Patrick GN, Sigurdson CJ. Diminished Neuronal ESCRT-0 Function Exacerbates AMPA Receptor Derangement and Accelerates Prion-Induced Neurodegeneration. J Neurosci 2023; 43:3970-3984. [PMID: 37019623 PMCID: PMC10219035 DOI: 10.1523/jneurosci.1878-22.2023] [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: 10/02/2022] [Revised: 03/22/2023] [Accepted: 03/27/2023] [Indexed: 04/07/2023] Open
Abstract
Endolysosomal defects in neurons are central to the pathogenesis of prion and other neurodegenerative disorders. In prion disease, prion oligomers traffic through the multivesicular body (MVB) and are routed for degradation in lysosomes or for release in exosomes, yet how prions impact proteostatic pathways is unclear. We found that prion-affected human and mouse brain showed a marked reduction in Hrs and STAM1 (ESCRT-0), which route ubiquitinated membrane proteins from early endosomes into MVBs. To determine how the reduction in ESCRT-0 impacts prion conversion and cellular toxicity in vivo, we prion-challenged conditional knockout mice (male and female) having Hrs deleted from neurons, astrocytes, or microglia. The neuronal, but not astrocytic or microglial, Hrs-depleted mice showed a shortened survival and an acceleration in synaptic derangements, including an accumulation of ubiquitinated proteins, deregulation of phosphorylated AMPA and metabotropic glutamate receptors, and profoundly altered synaptic structure, all of which occurred later in the prion-infected control mice. Finally, we found that neuronal Hrs (nHrs) depletion increased surface levels of the cellular prion protein, PrPC, which may contribute to the rapidly advancing disease through neurotoxic signaling. Taken together, the reduced Hrs in the prion-affected brain hampers ubiquitinated protein clearance at the synapse, exacerbates postsynaptic glutamate receptor deregulation, and accelerates neurodegeneration.SIGNIFICANCE STATEMENT Prion diseases are rapidly progressive neurodegenerative disorders characterized by prion aggregate spread through the central nervous system. Early disease features include ubiquitinated protein accumulation and synapse loss. Here, we investigate how prion aggregates alter ubiquitinated protein clearance pathways (ESCRT) in mouse and human prion-infected brain, discovering a marked reduction in Hrs. Using a prion-infection mouse model with neuronal Hrs (nHrs) depleted, we show that low neuronal Hrs is detrimental and markedly shortens survival time while accelerating synaptic derangements, including ubiquitinated protein accumulation, indicating that Hrs loss exacerbates prion disease progression. Additionally, Hrs depletion increases the surface distribution of prion protein (PrPC), linked to aggregate-induced neurotoxic signaling, suggesting that Hrs loss in prion disease accelerates disease through enhancing PrPC-mediated neurotoxic signaling.
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Affiliation(s)
- Jessica A Lawrence
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Patricia Aguilar-Calvo
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Daniel Ojeda-Juárez
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Helen Khuu
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Katrin Soldau
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Donald P Pizzo
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Jin Wang
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Adela Malik
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Timothy F Shay
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Erin E Sullivan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Brent Aulston
- Department of Neurosciences, University of California, San Diego, La Jolla, California 92093
| | - Seung Min Song
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Julia A Callender
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
| | - Henry Sanchez
- Department of Pathology, University of California, San Francisco, San Francisco, California 94143
| | - Michael D Geschwind
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California 94143
| | - Subhojit Roy
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
- Department of Neurosciences, University of California, San Diego, La Jolla, California 92093
| | - Robert A Rissman
- Department of Neurosciences, University of California, San Diego, La Jolla, California 92093
| | - JoAnn Trejo
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093
| | - Nobuyuki Tanaka
- Division of Tumor Immunobiology, Miyagi Cancer Center Research Institute, Natori 981-1293, Japan
- Division of Tumor Immunobiology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Chengbiao Wu
- Department of Neurosciences, University of California, San Diego, La Jolla, California 92093
| | - Xu Chen
- Department of Neurosciences, University of California, San Diego, La Jolla, California 92093
| | - Gentry N Patrick
- Department of Biology, University of California, San Diego, La Jolla, California 92093
| | - Christina J Sigurdson
- Department of Pathology, University of California, San Diego, La, Jolla, California, 92093
- Department of Pathology, Microbiology, and Immunology, University of California, Davis, Davis, California 95616
- Department of Medicine, University of California, San Diego, La Jolla, California 92093
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5
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Su F, Wei M, Sun M, Jiang L, Dong Z, Wang J, Zhang C. Deep learning-based synapse counting and synaptic ultrastructure analysis of electron microscopy images. J Neurosci Methods 2023; 384:109750. [PMID: 36414102 DOI: 10.1016/j.jneumeth.2022.109750] [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: 08/09/2022] [Revised: 11/11/2022] [Accepted: 11/18/2022] [Indexed: 11/21/2022]
Abstract
BACKGROUND Synapses are the connections between neurons in the central nervous system (CNS) or between neurons and other excitable cells in the peripheral nervous system (PNS), where electrical or chemical signals rapidly travel through one cell to another with high spatial precision. Synaptic analysis, based on synapse numbers and fine morphology, is the basis for understanding neurological functions and diseases. Manual analysis of synaptic structures in electron microscopy (EM) images is often limited by low efficiency and subjective bias. NEW METHOD We developed a multifunctional synaptic analysis system based on several advanced deep learning (DL) models. The system achieved synapse counting in low-magnification EM images and synaptic ultrastructure analysis in high-magnification EM images. RESULTS The synapse counting system based on ResNet18 and a Faster R-CNN model had a mean average precision (mAP) of 92.55%. For synaptic ultrastructure analysis, the Faster R-CNN model based on ResNet50 achieved a mAP of 91.60%, the DeepLab v3 + model based on ResNet50 enabled high performance in presynaptic and postsynaptic membrane segmentation with a global accuracy of 0.9811, and the Faster R-CNN model based on ResNet18 achieved a mAP of 91.41% for synaptic vesicle detection. CONCLUSIONS The proposed multifunctional synaptic analysis system may help to overcome the experimental bias inherent in manual analysis, thereby facilitating EM image-based synaptic function studies.
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Affiliation(s)
- Feng Su
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China; Chinese Institute for Brain Research, Beijing 102206, China; State Key Laboratory of Translational Medicine and Innovative Drug Development, Nanjing 210000, Jiangsu, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Mengping Wei
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
| | - Meng Sun
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
| | - Lixin Jiang
- Peking University Institute of Mental Health (Sixth Hospital), No. 51 Huayuanbei Road, Haidian District, Beijing 100191, China
| | - Zhaoqi Dong
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
| | - Jue Wang
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China
| | - Chen Zhang
- Department of Neurobiology, School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing 100069, China; Chinese Institute for Brain Research, Beijing 102206, China; State Key Laboratory of Translational Medicine and Innovative Drug Development, Nanjing 210000, Jiangsu, China.
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6
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Overhoff M, Tellkamp F, Hess S, Tolve M, Tutas J, Faerfers M, Ickert L, Mohammadi M, De Bruyckere E, Kallergi E, Delle Vedove A, Nikoletopoulou V, Wirth B, Isensee J, Hucho T, Puchkov D, Isbrandt D, Krueger M, Kloppenburg P, Kononenko NL. Autophagy regulates neuronal excitability by controlling cAMP/protein kinase A signaling at the synapse. EMBO J 2022; 41:e110963. [PMID: 36217825 PMCID: PMC9670194 DOI: 10.15252/embj.2022110963] [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: 02/17/2022] [Revised: 09/10/2022] [Accepted: 09/14/2022] [Indexed: 01/13/2023] Open
Abstract
Autophagy provides nutrients during starvation and eliminates detrimental cellular components. However, accumulating evidence indicates that autophagy is not merely a housekeeping process. Here, by combining mouse models of neuron-specific ATG5 deficiency in either excitatory or inhibitory neurons with quantitative proteomics, high-content microscopy, and live-imaging approaches, we show that autophagy protein ATG5 functions in neurons to regulate cAMP-dependent protein kinase A (PKA)-mediated phosphorylation of a synapse-confined proteome. This function of ATG5 is independent of bulk turnover of synaptic proteins and requires the targeting of PKA inhibitory R1 subunits to autophagosomes. Neuronal loss of ATG5 causes synaptic accumulation of PKA-R1, which sequesters the PKA catalytic subunit and diminishes cAMP/PKA-dependent phosphorylation of postsynaptic cytoskeletal proteins that mediate AMPAR trafficking. Furthermore, ATG5 deletion in glutamatergic neurons augments AMPAR-dependent excitatory neurotransmission and causes the appearance of spontaneous recurrent seizures in mice. Our findings identify a novel role of autophagy in regulating PKA signaling at glutamatergic synapses and suggest the PKA as a target for restoration of synaptic function in neurodegenerative conditions with autophagy dysfunction.
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Affiliation(s)
- Melina Overhoff
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Frederik Tellkamp
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Faculty of Mathematics and Natural Sciences, Institute of GeneticsUniversity of CologneCologneGermany
| | - Simon Hess
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Faculty of Mathematics and Natural Sciences, Institute of ZoologyUniversity of CologneCologneGermany
| | - Marianna Tolve
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Center for Physiology and Pathophysiology, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
| | - Janine Tutas
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Marcel Faerfers
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Lotte Ickert
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Center for Physiology and Pathophysiology, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
| | - Milad Mohammadi
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Elodie De Bruyckere
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
| | - Emmanouela Kallergi
- Département des Neurosciences FondamentalesUniversity of LausanneLausanneSwitzerland
| | - Andrea Delle Vedove
- Institute of Human Genetics, Center for Molecular Medicine Cologne, Center for Rare Diseases Cologne, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
| | | | - Brunhilde Wirth
- Faculty of Mathematics and Natural Sciences, Institute of GeneticsUniversity of CologneCologneGermany,Institute of Human Genetics, Center for Molecular Medicine Cologne, Center for Rare Diseases Cologne, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
| | - Joerg Isensee
- Translational Pain Research, Department of Anaesthesiology and Intensive Care Medicine, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
| | - Tim Hucho
- Translational Pain Research, Department of Anaesthesiology and Intensive Care Medicine, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
| | - Dmytro Puchkov
- Leibniz Institute for Molecular Pharmacology (FMP)BerlinGermany
| | - Dirk Isbrandt
- Institute for Molecular and Behavioral Neuroscience, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany,Experimental NeurophysiologyGerman Center for Neurodegenerative DiseasesBonnGermany
| | - Marcus Krueger
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Faculty of Mathematics and Natural Sciences, Institute of GeneticsUniversity of CologneCologneGermany
| | - Peter Kloppenburg
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Faculty of Mathematics and Natural Sciences, Institute of ZoologyUniversity of CologneCologneGermany
| | - Natalia L Kononenko
- Cologne Excellence Cluster Cellular Stress Response in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany,Center for Physiology and Pathophysiology, Faculty of Medicine and University Hospital CologneUniversity of CologneCologneGermany
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7
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Heuser JE. The Structural Basis of Long-Term Potentiation in Hippocampal Synapses, Revealed by Electron Microscopy Imaging of Lanthanum-Induced Synaptic Vesicle Recycling. Front Cell Neurosci 2022; 16:920360. [PMID: 35978856 PMCID: PMC9376242 DOI: 10.3389/fncel.2022.920360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022] Open
Abstract
Hippocampal neurons in dissociated cell cultures were exposed to the trivalent cation lanthanum for short periods (15–30 min) and prepared for electron microscopy (EM), to evaluate the stimulatory effects of this cation on synaptic ultrastructure. Not only were characteristic ultrastructural changes of exaggerated synaptic vesicle turnover seen within the presynapses of these cultures—including synaptic vesicle depletion and proliferation of vesicle-recycling structures—but the overall architecture of a large proportion of the synapses in the cultures was dramatically altered, due to large postsynaptic “bulges” or herniations into the presynapses. Moreover, in most cases, these postsynaptic herniations or protrusions produced by lanthanum were seen by EM to distort or break or “perforate” the so-called postsynaptic densities (PSDs) that harbor receptors and recognition molecules essential for synaptic function. These dramatic EM observations lead us to postulate that such PSD breakages or “perforations” could very possibly create essential substrates or “tags” for synaptic growth, simply by creating fragmented free edges around the PSDs, into which new receptors and recognition molecules could be recruited more easily, and thus, they could represent the physical substrate for the important synaptic growth process known as “long-term potentiation” (LTP). All of this was created simply in hippocampal dissociated cell cultures, and simply by pushing synaptic vesicle recycling way beyond its normal limits with the trivalent cation lanthanum, but we argued in this report that such fundamental changes in synaptic architecture—given that they can occur at all—could also occur at the extremes of normal neuronal activity, which are presumed to lead to learning and memory.
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8
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Hao Y, Guo X, Wang X, Shi X, Shi M, Meng L, Gong M, Fu Y, Zhao Y, Du Y, Yang R, Li W, Lian K, Song L, Wang S, Li Y, Shi Y, Shi H. Maternal exposure to triclosan during lactation alters social behaviors and the hippocampal ultrastructure in adult mouse offspring. Toxicol Appl Pharmacol 2022; 449:116131. [PMID: 35718130 DOI: 10.1016/j.taap.2022.116131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 05/08/2022] [Accepted: 06/11/2022] [Indexed: 10/18/2022]
Abstract
We recently reported that exposure to triclosan (TCS), a broad-spectrum antibacterial agent, affects social behaviors in adult mice, however, the long-lasting effects of TCS exposure during early life on social behaviors are still elusive. The present study aimed to investigate the long-lasting impacts of adding TCS to the maternal drinking water during lactation on the social behaviors of adult mouse offspring and to explore the potential mechanism underlying these effects. The behavioral results showed that TCS exposure decreased body weight, increased depression-like behavior and decreased social dominance in both male and female offspring, as well as increased anxiety-like behavior and bedding preference in female offspring. In addition, enzyme-linked immunosorbent assay (ELISA) indicated that TCS exposure increased peripheral proinflammatory cytokine levels, altered serum oxytocin (OT) levels, and downregulated the expression of postsynaptic density protein 95 (PSD-95) in the hippocampus. Morphological analysis by transmission electron microscopy (TEM) demonstrated that exposure to TCS induced morphological changes to synapses and neurons in the hippocampus of offspring. These findings suggested that TCS exposure during lactation contributed to abnormal social behaviors accompanied by increased peripheral inflammation and altered hippocampal neuroplasticity, which provides a deeper understanding of the effects of TCS exposure during early life on brain function and behavioral phenotypes.
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Affiliation(s)
- Ying Hao
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Xiangfei Guo
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Xinhao Wang
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Xiaorui Shi
- Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China; Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Mengxu Shi
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China
| | - Li Meng
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China
| | - Miao Gong
- Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China; Experimental Center for Teaching, Hebei Medical University, Shijiazhuang 050017, China
| | - Yaling Fu
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Ye Zhao
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Yuru Du
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Rui Yang
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Wenshuya Li
- Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Kaoqi Lian
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China
| | - Li Song
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Sheng Wang
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China
| | - Youdong Li
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China
| | - Yun Shi
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Department of Biochemistry and Molecular Biology, The Key Laboratory of Neural and Vascular Biology, Ministry of Education of China, Hebei Medical University, Shijiazhuang, Hebei 050017, China.
| | - Haishui Shi
- Neuroscience Research Center, Institute of Medical and Health Science, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key laboratory of Neurophysiology, Hebei Medical University, 050017, China.
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9
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Hao Y, Meng L, Zhang Y, Chen A, Zhao Y, Lian K, Guo X, Wang X, Du Y, Wang X, Li X, Song L, Shi Y, Yin X, Gong M, Shi H. Effects of chronic triclosan exposure on social behaviors in adult mice. JOURNAL OF HAZARDOUS MATERIALS 2022; 424:127562. [PMID: 34736200 DOI: 10.1016/j.jhazmat.2021.127562] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 10/01/2021] [Accepted: 10/18/2021] [Indexed: 06/13/2023]
Abstract
Triclosan (TCS), a newly identified environmental endocrine disruptor (EED) in household products, has been reported to have toxic effects on animals and humans. The effects of TCS exposure on individual social behaviors and the potential underlying mechanisms are still unknown. This study investigated the behavioral effects of 42-day exposure to TCS (0, 50, 100 mg/kg) in drinking water using the open field test (OFT), social dominance test (SDT), social interaction test (SIT), and novel object recognition task (NOR). Using 16S rRNA sequencing analysis and transmission electron microscopy (TEM), we observed the effects of TCS exposure on the gut microbiota and ultrastructure of hippocampal neurons and synapses. Behavioral results showed that chronic TCS exposure reduced the social dominance of male and female mice. TCS exposure also reduced social interaction in male mice and impaired memory formation in female mice. Analysis of the gut microbiota showed that TCS exposure increased the relative abundance of the Proteobacteria and Actinobacteria phyla in female mice. Ultrastructural analysis revealed that TCS exposure induced ultrastructural damage to hippocampal neurons and synapses. These findings suggest that TCS exposure may affect social behaviors, which may be caused by altered gut microbiota and impaired plasticity of hippocampal neurons and synapses.
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Affiliation(s)
- Ying Hao
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China
| | - Li Meng
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China
| | - Yan Zhang
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China
| | - Aixin Chen
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China
| | - Ye Zhao
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China
| | - Kaoqi Lian
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China
| | - Xiangfei Guo
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China
| | - Xinhao Wang
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China
| | - Yuru Du
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China
| | - Xi Wang
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China
| | - Xuzi Li
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China
| | - Li Song
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China
| | - Yun Shi
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China
| | - Xi Yin
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Department of Functional Region of Diagnosis, Fourth Hospital of Hebei Medical University, Shijiazhuang 050011, China
| | - Miao Gong
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Experimental Center for Teaching, Hebei Medical University, Shijiazhuang 050017, China.
| | - Haishui Shi
- Neuroscience Research Center, Institute of Medical and Health Science of HeBMU, Hebei Medical University, Shijiazhuang 050017, China; Hebei Key Laboratory of Neurophysiology, Hebei Medicinal University, 050017, China; Research Unit of Digestive Tract Microecosystem Pharmacology and Toxicology, Chinese Academy of Medical Sciences, Shijiazhuang 050017, China.
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10
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Arhgap22 Disruption Leads to RAC1 Hyperactivity Affecting Hippocampal Glutamatergic Synapses and Cognition in Mice. Mol Neurobiol 2021; 58:6092-6110. [PMID: 34455539 PMCID: PMC8639580 DOI: 10.1007/s12035-021-02502-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 07/15/2021] [Indexed: 11/03/2022]
Abstract
Rho GTPases are a class of G-proteins involved in several aspects of cellular biology, including the regulation of actin cytoskeleton. The most studied members of this family are RHOA and RAC1 that act in concert to regulate actin dynamics. Recently, Rho GTPases gained much attention as synaptic regulators in the mammalian central nervous system (CNS). In this context, ARHGAP22 protein has been previously shown to specifically inhibit RAC1 activity thus standing as critical cytoskeleton regulator in cancer cell models; however, whether this function is maintained in neurons in the CNS is unknown. Here, we generated a knockout animal model for arhgap22 and provided evidence of its role in the hippocampus. Specifically, we found that ARHGAP22 absence leads to RAC1 hyperactivity and to an increase in dendritic spine density with defects in synaptic structure, molecular composition, and plasticity. Furthermore, arhgap22 silencing causes impairment in cognition and a reduction in anxiety-like behavior in mice. We also found that inhibiting RAC1 restored synaptic plasticity in ARHGAP22 KO mice. All together, these results shed light on the specific role of ARHGAP22 in hippocampal excitatory synapse formation and function as well as in learning and memory behaviors.
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11
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Suzuki T, Terada N, Higashiyama S, Kametani K, Shirai Y, Honda M, Kai T, Li W, Tabuchi K. Non-microtubule tubulin-based backbone and subordinate components of postsynaptic density lattices. Life Sci Alliance 2021; 4:4/7/e202000945. [PMID: 34006534 PMCID: PMC8326785 DOI: 10.26508/lsa.202000945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 04/19/2021] [Accepted: 04/26/2021] [Indexed: 12/28/2022] Open
Abstract
This study proposes a postsynaptic density (PSD) lattice model comprising a non-microtubule tubulin-based backbone structure and its associated proteins, including various PSD scaffold/adaptor proteins and other PSD proteins. A purification protocol was developed to identify and analyze the component proteins of a postsynaptic density (PSD) lattice, a core structure of the PSD of excitatory synapses in the central nervous system. “Enriched”- and “lean”-type PSD lattices were purified by synaptic plasma membrane treatment to identify the protein components by comprehensive shotgun mass spectrometry and group them into minimum essential cytoskeleton (MEC) and non-MEC components. Tubulin was found to be a major component of the MEC, with non-microtubule tubulin widely distributed on the purified PSD lattice. The presence of tubulin in and around PSDs was verified by post-embedding immunogold labeling EM of cerebral cortex. Non-MEC proteins included various typical scaffold/adaptor PSD proteins and other class PSD proteins. Thus, this study provides a new PSD lattice model consisting of non-microtubule tubulin-based backbone and various non-MEC proteins. Our findings suggest that tubulin is a key component constructing the backbone and that the associated components are essential for the versatile functions of the PSD.
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Affiliation(s)
- Tatsuo Suzuki
- Department of Molecular and Cellular Physiology, Shinshu University Academic Assembly, Institute of Medicine, Shinshu University Academic Assembly, Matsumoto, Japan
| | - Nobuo Terada
- Health Science Division, Department of Medical Sciences, Graduate School of Medicine, Science and Technology, Shinshu University, Matsumoto, Nagano, Japan
| | - Shigeki Higashiyama
- Department of Cell Growth and Tumor Regulation, Proteo-Science Center, Ehime University, To-on, Ehime, Japan
| | - Kiyokazu Kametani
- Department of Veterinary Anatomy, Faculty of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan
| | - Yoshinori Shirai
- Department of Molecular and Cellular Physiology, Shinshu University Academic Assembly, Institute of Medicine, Shinshu University Academic Assembly, Matsumoto, Japan
| | - Mamoru Honda
- Bioscience Group, Center for Precision Medicine Supports, Pharmaceuticals and Life Sciences Division, Shimadzu Techno-Research, INC, Kyoto, Japan
| | - Tsutomu Kai
- Bioscience Group, Center for Precision Medicine Supports, Pharmaceuticals and Life Sciences Division, Shimadzu Techno-Research, INC, Kyoto, Japan
| | - Weidong Li
- Bio-X Institutes, Key Laboratory for the Genetics of Development and Neuropsychiatric Disorders (Ministry of Education), Shanghai Key Laboratory of Psychotic Disorders, and Brain Science and Technology Research Center, Shanghai Jiao Tong University, Shanghai, China.,Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research Shinshu University, Matsumoto, Japan
| | - Katsuhiko Tabuchi
- Department of Molecular and Cellular Physiology, Shinshu University Academic Assembly, Institute of Medicine, Shinshu University Academic Assembly, Matsumoto, Japan.,Department of Biological Sciences for Intractable Neurological Diseases, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research Shinshu University, Matsumoto, Japan
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12
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Colombo MN, Maiellano G, Putignano S, Scandella L, Francolini M. Comparative 2D and 3D Ultrastructural Analyses of Dendritic Spines from CA1 Pyramidal Neurons in the Mouse Hippocampus. Int J Mol Sci 2021; 22:ijms22031188. [PMID: 33530380 PMCID: PMC7865959 DOI: 10.3390/ijms22031188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/19/2021] [Accepted: 01/22/2021] [Indexed: 11/21/2022] Open
Abstract
Three-dimensional (3D) reconstruction from electron microscopy (EM) datasets is a widely used tool that has improved our knowledge of synapse ultrastructure and organization in the brain. Rearrangements of synapse structure following maturation and in synaptic plasticity have been broadly described and, in many cases, the defective architecture of the synapse has been associated to functional impairments. It is therefore important, when studying brain connectivity, to map these rearrangements with the highest accuracy possible, considering the affordability of the different EM approaches to provide solid and reliable data about the structure of such a small complex. The aim of this work is to compare quantitative data from two dimensional (2D) and 3D EM of mouse hippocampal CA1 (apical dendrites), to define whether the results from the two approaches are consistent. We examined asymmetric excitatory synapses focusing on post synaptic density and dendritic spine area and volume as well as spine density, and we compared the results obtained with the two methods. The consistency between the 2D and 3D results questions the need—for many applications—of using volumetric datasets (costly and time consuming in terms of both acquisition and analysis), with respect to the more accessible measurements from 2D EM projections.
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13
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Glutamatergic Dysfunction and Synaptic Ultrastructural Alterations in Schizophrenia and Autism Spectrum Disorder: Evidence from Human and Rodent Studies. Int J Mol Sci 2020; 22:ijms22010059. [PMID: 33374598 PMCID: PMC7793137 DOI: 10.3390/ijms22010059] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 12/15/2020] [Accepted: 12/22/2020] [Indexed: 12/12/2022] Open
Abstract
The correlation between dysfunction in the glutamatergic system and neuropsychiatric disorders, including schizophrenia and autism spectrum disorder, is undisputed. Both disorders are associated with molecular and ultrastructural alterations that affect synaptic plasticity and thus the molecular and physiological basis of learning and memory. Altered synaptic plasticity, accompanied by changes in protein synthesis and trafficking of postsynaptic proteins, as well as structural modifications of excitatory synapses, are critically involved in the postnatal development of the mammalian nervous system. In this review, we summarize glutamatergic alterations and ultrastructural changes in synapses in schizophrenia and autism spectrum disorder of genetic or drug-related origin, and briefly comment on the possible reversibility of these neuropsychiatric disorders in the light of findings in regular synaptic physiology.
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14
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Tao-Cheng JH. Activity-dependent redistribution of CaMKII in the postsynaptic compartment of hippocampal neurons. Mol Brain 2020; 13:53. [PMID: 32238193 PMCID: PMC7110642 DOI: 10.1186/s13041-020-00594-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 03/23/2020] [Indexed: 11/10/2022] Open
Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII), an abundant protein in neurons, is involved in synaptic plasticity and learning. CaMKII associates with multiple proteins located at or near the postsynaptic density (PSD), and CaMKII is known to translocate from cytoplasm to PSD under excitatory conditions. The present study examined the laminar distribution of CaMKII at the PSD by immunogold labeling in dissociated hippocampal cultures under low calcium (EGTA or APV), control, and stimulated (depolarization with high K+ or NMDA) conditions. The patterns of CaMKII distribution are classified with particular reference to the two layers of the PSD: (1) the PSD core, a layer within ~ 30-40 nm to the postsynaptic membrane, and (2) the PSD pallium, a deeper layer beyond the PSD core, ~ 100-120 nm from the postsynaptic membrane. Under low calcium conditions, a subpopulation (40%) of synapses stood out with no CaMKII labeling at the PSD, indicating that localization of CaMKII at the PSD is sensitive to calcium levels. Under control conditions, the majority (~ 60-70%) of synapses had label for CaMKII dispersed evenly in the spine, including the PSD and the nearby cytoplasm. Upon stimulation, the majority (60-75%) of synapses had label for CaMKII concentrated at the PSD, delineating the PSD pallium from the cytoplasm. Median distance of label for CaMKII to postsynaptic membrane was higher in low calcium samples (68-77 nm), than in control (59-63 nm) and stimulated samples (49-53 nm). Thus, upon stimulation, not only more CaMKII translocated to the PSD, but they also were closer to the postsynaptic membrane. Additionally, there were two relatively infrequent labeling patterns that may represent intermediate stages of CaMKII distribution between basal and stimulated conditions: (1) one type showed label preferentially localized near the PSD core where CaMKII may be binding to NR2B, an NMDA receptor concentrated at the PSD core, and (2) the second type showed label preferentially in the PSD pallium, where CaMKII may be binding to Shank, a PSD scaffold protein located in the PSD pallium. Both of these distribution patterns may portray the initial stages of CaMKII translocation upon synaptic activation. In addition to binding to PSD proteins, the concentrated CaMKII labeling at the PSD under heightened excitatory conditions could also be formed by self-clustering of CaMKII molecules recruited to the PSD. Most importantly, these accumulated CaMKII molecules do not extend beyond the border of the PSD pallium, and are likely held in the pallium by binding to Shank under these conditions.
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Affiliation(s)
- Jung-Hwa Tao-Cheng
- NINDS Electron Microscopy Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
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