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Ku HY, Bilder D. Basement membrane patterning by spatial deployment of a secretion-regulating protease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.06.602330. [PMID: 39026720 PMCID: PMC11257494 DOI: 10.1101/2024.07.06.602330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
While paradigms for patterning of cell fates in development are well-established, paradigms for patterning morphogenesis, particularly when organ shape is influenced by the extracellular matrix (ECM), are less so. Morphogenesis of the Drosophila egg chamber (follicle) depends on anterior-posterior distribution of basement membrane (BM) components such as Collagen IV (Col4), whose symmetric gradient creates tissue mechanical properties that specify the degree of elongation. Here we show that the gradient is not regulated by Col4 transcription but instead relies on post-transcriptional mechanisms. The metalloprotease ADAMTS-A, expressed in a gradient inverse to that of Col4, limits Col4 deposition in the follicle center and manipulation of its levels can cause either organ hyper- or hypo-elongation. We present evidence that ADAMTS-A acts within the secretory pathway, rather than extracellularly, to limit Col4 incorporation into the BM. High levels of ADAMTS-A in follicle termini are normally dispensable but suppress Col4 incorporation when transcription is elevated. Our data show how an organ can employ patterned expression of ECM proteases with intracellular as well as extracellular activity to specify BM properties that control shape.
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Affiliation(s)
- Hui-Yu Ku
- Department of Molecular and Cell Biology, University of California-Berkeley Berkeley CA, 94720, USA
| | - David Bilder
- Department of Molecular and Cell Biology, University of California-Berkeley Berkeley CA, 94720, USA
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2
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Sharma A, Hill KE, Schwarzbauer JE. Extracellular matrix composition affects outgrowth of dendrites and dendritic spines on cortical neurons. Front Cell Neurosci 2023; 17:1177663. [PMID: 37388410 PMCID: PMC10300442 DOI: 10.3389/fncel.2023.1177663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/29/2023] [Indexed: 07/01/2023] Open
Abstract
The composition of the extracellular matrix (ECM) in nervous tissue plays an important role in controlling neuronal outgrowth and synapse development. Changes in both protein and glycosaminoglycan components of the ECM occur with tissue injury and may affect neuron growth. To investigate neuron responses to alterations in fibronectin (FN), a major component of the wound ECM, we grew cortical neurons on cell-derived decellularized matrices composed of wild type FN (FN+/+) or of a mutant form of FN (FNΔ/+) from which the III13 heparin-binding site had been deleted by CRISPR-Cas 9 gene editing. The most significant effect of the mutant FN was a reduction in dendrite outgrowth. Not only were dendrites shorter on mutant FNΔ/+-collagen (COL) matrix than on wild type (FN+/+-COL) matrix, but the number of dendrites and dendritic spines per neuron and the spine densities were also dramatically reduced on FNΔ/+-COL matrices. Mass spectrometry and immunostaining identified a reduction in tenascin-C (TN-C) levels in the mutant matrix. TN-C is an ECM protein that binds to the III13 site of FN and modulates cell-matrix interactions and has been linked to dendrite development. We propose that TN-C binding to FN in the wound matrix supports dendrite and spine development during repair of damaged neural tissue. Overall, these results show that changes in ECM composition can dramatically affect elaboration of neurites and support the idea that the ECM microenvironment controls neuron morphology and connectivity.
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Affiliation(s)
| | | | - Jean E. Schwarzbauer
- Department of Molecular Biology, Princeton University, Princeton, NJ, United States
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3
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Rike WA, Stern S. Proteins and Transcriptional Dysregulation of the Brain Extracellular Matrix in Parkinson's Disease: A Systematic Review. Int J Mol Sci 2023; 24:ijms24087435. [PMID: 37108598 PMCID: PMC10138539 DOI: 10.3390/ijms24087435] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/06/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
The extracellular matrix (ECM) of the brain is a dynamic structure made up of a vast network of bioactive macromolecules that modulate cellular events. Structural, organizational, and functional changes in these macromolecules due to genetic variation or environmental stressors are thought to affect cellular functions and may result in disease. However, most mechanistic studies to date usually focus on the cellular aspects of diseases and pay less attention to the relevance of the processes governing the dynamic nature of the extracellular matrix in disease pathogenesis. Thus, due to the ECM's diversified biological roles, increasing interest in its involvement in disease, and the lack of sufficient compiled evidence regarding its relationship with Parkinson's disease (PD) pathology, we aimed to compile the existing evidence to boost the current knowledge on the area and provide refined guidance for the future research. Here, in this review, we gathered postmortem brain tissue and induced pluripotent stem cell (iPSC)-related studies from PubMed and Google Scholar to identify, summarize and describe common macromolecular alterations in the expression of brain ECM components in Parkinson's disease (PD). A literature search was conducted up until 10 February 2023. The overall hits from the database and manual search for proteomic and transcriptome studies were 1243 and 1041 articles, respectively. Following a full-text review, 10 articles from proteomic and 24 from transcriptomic studies were found to be eligible for inclusion. According to proteomic studies, proteins such as collagens, fibronectin, annexins, and tenascins were recognized to be differentially expressed in Parkinson's disease. Transcriptomic studies displayed dysregulated pathways including ECM-receptor interaction, focal adhesion, and cell adhesion molecules in Parkinson's disease. A limited number of relevant studies were accessed from our search, indicating that much work remains to be carried out to better understand the roles of the ECM in neurodegeneration and Parkinson's disease. However, we believe that our review will elicit focused primary studies and thus support the ongoing efforts of the discovery and development of diagnostic biomarkers as well as therapeutic agents for Parkinson's disease.
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Affiliation(s)
- Wote Amelo Rike
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Shani Stern
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
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4
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Peppercorn K, Kleffmann T, Hughes SM, Tate WP. Secreted Amyloid Precursor Protein Alpha (sAPPα) Regulates the Cellular Proteome and Secretome of Mouse Primary Astrocytes. Int J Mol Sci 2023; 24:ijms24087165. [PMID: 37108327 PMCID: PMC10138557 DOI: 10.3390/ijms24087165] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/23/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
Secreted amyloid precursor protein alpha (sAPPα), processed from a parent mammalian brain protein, amyloid precursor protein, can modulate learning and memory. Recently it has been shown to modulate the transcriptome and proteome of human neurons, including proteins with neurological functions. Here, we analysed whether the acute administration of sAPPα facilitated changes in the proteome and secretome of mouse primary astrocytes in culture. Astrocytes contribute to the neuronal processes of neurogenesis, synaptogenesis and synaptic plasticity. Cortical mouse astrocytes in culture were exposed to 1 nM sAPPα, and changes in both the whole-cell proteome (2 h) and the secretome (6 h) were identified with Sequential Window Acquisition of All Theoretical Fragment Ion Spectra-Mass Spectrometry (SWATH-MS). Differentially regulated proteins were identified in both the cellular proteome and secretome that are involved with neurologically related functions of the normal physiology of the brain and central nervous system. Groups of proteins have a relationship to APP and have roles in the modulation of cell morphology, vesicle dynamics and the myelin sheath. Some are related to pathways containing proteins whose genes have been previously implicated in Alzheimer's disease (AD). The secretome is also enriched in proteins related to Insulin Growth Factor 2 (IGF2) signaling and the extracellular matrix (ECM). There is the promise that a more specific investigation of these proteins will help to understand the mechanisms of how sAPPα signaling affects memory formation.
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Affiliation(s)
- Katie Peppercorn
- Department of Biochemistry, School of Biomedical Sciences, Division of Health Sciences, University of Otago, Dunedin 9016, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin 9016, New Zealand
| | - Torsten Kleffmann
- Research Infrastructure Centre, Division of Health Sciences, University of Otago, Dunedin 9016, New Zealand
| | - Stephanie M Hughes
- Department of Biochemistry, School of Biomedical Sciences, Division of Health Sciences, University of Otago, Dunedin 9016, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin 9016, New Zealand
- Genetics Otago, University of Otago, Dunedin 9016, New Zealand
| | - Warren P Tate
- Department of Biochemistry, School of Biomedical Sciences, Division of Health Sciences, University of Otago, Dunedin 9016, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin 9016, New Zealand
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5
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Barnett SFH, Goult BT. The MeshCODE to scale-visualising synaptic binary information. Front Cell Neurosci 2022; 16:1014629. [PMID: 36467609 PMCID: PMC9716431 DOI: 10.3389/fncel.2022.1014629] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 11/01/2022] [Indexed: 08/31/2023] Open
Abstract
The Mercator projection map of the world provides a useful, but distorted, view of the relative scale of countries. Current cellular models suffer from a similar distortion. Here, we undertook an in-depth structural analysis of the molecular dimensions in the cell's computational machinery, the MeshCODE, that is assembled from a meshwork of binary switches in the scaffolding proteins talin and vinculin. Talin contains a series of force-dependent binary switches and each domain switching state introduces quantised step-changes in talin length on a micrometre scale. The average dendritic spine is 1 μm in diameter so this analysis identifies a plausible Gearbox-like mechanism for dynamic regulation of synaptic function, whereby the positioning of enzymes and substrates relative to each other, mechanically-encoded by the MeshCODE switch patterns, might control synaptic transmission. Based on biophysical rules and experimentally derived distances, this analysis yields a novel perspective on biological digital information.
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Affiliation(s)
- Samuel F. H. Barnett
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Benjamin T. Goult
- School of Biosciences, University of Kent, Canterbury, United Kingdom
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6
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Enhancement of Neuroglial Extracellular Matrix Formation and Physiological Activity of Dopaminergic Neural Cocultures by Macromolecular Crowding. Cells 2022; 11:cells11142131. [PMID: 35883574 PMCID: PMC9317039 DOI: 10.3390/cells11142131] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/28/2022] [Accepted: 07/01/2022] [Indexed: 02/06/2023] Open
Abstract
The neuroglial extracellular matrix (ECM) provides critical support and physiological cues for the proper growth, differentiation, and function of neuronal cells in the brain. However, in most in vitro settings that study neural physiology, cells are grown as monolayers on stiff surfaces that maximize adhesion and proliferation, and, therefore, they lack the physiological cues that ECM in native neuronal tissues provides. Macromolecular crowding (MMC) is a biophysical phenomenon based on the principle of excluded volume that can be harnessed to induce native ECM deposition by cells in culture. Here, we show that MMC using two species of Ficoll with vitamin C supplementation significantly boosts deposition of relevant brain ECM by cultured human astrocytes. Dopaminergic neurons cocultured on this astrocyte–ECM bed prepared under MMC treatment showed longer and denser neuronal extensions, a higher number of pre ad post synaptic contacts, and increased physiological activity, as evidenced by higher frequency calcium oscillation, compared to standard coculture conditions. When the pharmacological activity of various compounds was tested on MMC-treated cocultures, their responses were enhanced, and for apomorphine, a D2-receptor agonist, it was inverted in comparison to control cell culture conditions, thus emulating responses observed in in vivo settings. These results indicate that macromolecular crowding can harness the ECM-building potential of human astrocytes in vitro forming an ultra-flat 3D microenvironment that makes neural cultures more physiological and pharmacological relevant.
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7
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Zou S, Pan BX. Post-synaptic specialization of the neuromuscular junction: junctional folds formation, function, and disorders. Cell Biosci 2022; 12:93. [PMID: 35718785 PMCID: PMC9208267 DOI: 10.1186/s13578-022-00829-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 06/05/2022] [Indexed: 11/14/2022] Open
Abstract
Post-synaptic specialization is critical to the neurotransmitter release and action potential conduction. The neuromuscular junctions (NMJs) are the synapses between the motor neurons and muscle cells and have a more specialized post-synaptic membrane than synapses in the central nervous system (CNS). The sarcolemma within NMJ folded to form some invagination portions called junctional folds (JFs), and they have important roles in maintaining the post-synaptic membrane structure. The NMJ formation and the acetylcholine receptor (AChR) clustering signal pathway have been extensively studied and reviewed. Although it has been suggested that JFs are related to maintaining the safety factor of neurotransmitter release, the formation mechanism and function of JFs are still unclear. This review will focus on the JFs about evolution, formation, function, and disorders. Anticipate understanding of where they are coming from and where we will study in the future.
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Affiliation(s)
- Suqi Zou
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, P. R. China.
- School of Life Sciences, Nanchang University, Nanchang, 330031, Jiangxi, P. R. China.
| | - Bing-Xing Pan
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, 330031, Jiangxi, P. R. China
- School of Life Sciences, Nanchang University, Nanchang, 330031, Jiangxi, P. R. China
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8
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Peppercorn K, Kleffmann T, Jones O, Hughes S, Tate W. Secreted Amyloid Precursor Protein Alpha, a Neuroprotective Protein in the Brain Has Widespread Effects on the Transcriptome and Proteome of Human Inducible Pluripotent Stem Cell-Derived Glutamatergic Neurons Related to Memory Mechanisms. Front Neurosci 2022; 16:858524. [PMID: 35692428 PMCID: PMC9179159 DOI: 10.3389/fnins.2022.858524] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 03/14/2022] [Indexed: 11/18/2022] Open
Abstract
Secreted amyloid precursor protein alpha (sAPPα) processed from a parent human brain protein, APP, can modulate learning and memory. It has potential for development as a therapy preventing, delaying, or even reversing Alzheimer’s disease. In this study a comprehensive analysis to understand how it affects the transcriptome and proteome of the human neuron was undertaken. Human inducible pluripotent stem cell (iPSC)-derived glutamatergic neurons in culture were exposed to 1 nM sAPPα over a time course and changes in the transcriptome and proteome were identified with RNA sequencing and Sequential Window Acquisition of All THeoretical Fragment Ion Spectra-Mass Spectrometry (SWATH-MS), respectively. A large subset (∼30%) of differentially expressed transcripts and proteins were functionally involved with the molecular biology of learning and memory, consistent with reported links of sAPPα to memory enhancement, as well as neurogenic, neurotrophic, and neuroprotective phenotypes in previous studies. Differentially regulated proteins included those encoded in previously identified Alzheimer’s risk genes, APP processing related proteins, proteins involved in synaptogenesis, neurotransmitters, receptors, synaptic vesicle proteins, cytoskeletal proteins, proteins involved in protein and organelle trafficking, and proteins important for cell signalling, transcriptional splicing, and functions of the proteasome and lysosome. We have identified a complex set of genes affected by sAPPα, which may aid further investigation into the mechanism of how this neuroprotective protein affects memory formation and how it might be used as an Alzheimer’s disease therapy.
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Affiliation(s)
- Katie Peppercorn
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Torsten Kleffmann
- Division of Health Sciences, Research Infrastructure Centre, University of Otago, Dunedin, New Zealand
| | - Owen Jones
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Stephanie Hughes
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Warren Tate
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- *Correspondence: Warren Tate,
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9
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Zhou X, Vachon C, Cizeron M, Romatif O, Bülow HE, Jospin M, Bessereau JL. The HSPG syndecan is a core organizer of cholinergic synapses. J Cell Biol 2021; 220:212450. [PMID: 34213535 PMCID: PMC8258370 DOI: 10.1083/jcb.202011144] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 04/13/2021] [Accepted: 05/26/2021] [Indexed: 12/15/2022] Open
Abstract
The extracellular matrix has emerged as an active component of chemical synapses regulating synaptic formation, maintenance, and homeostasis. The heparan sulfate proteoglycan (HSPG) syndecans are known to regulate cellular and axonal migration in the brain. They are also enriched at synapses, but their synaptic functions remain more elusive. Here, we show that SDN-1, the sole orthologue of syndecan in C. elegans, is absolutely required for the synaptic clustering of homomeric α7-like acetylcholine receptors (AChRs) and regulates the synaptic content of heteromeric AChRs. SDN-1 is concentrated at neuromuscular junctions (NMJs) by the neurally secreted synaptic organizer Ce-Punctin/MADD-4, which also activates the transmembrane netrin receptor DCC. Those cooperatively recruit the FARP and CASK orthologues that localize α7-like-AChRs at cholinergic NMJs through physical interactions. Therefore, SDN-1 stands at the core of the cholinergic synapse organization by bridging the extracellular synaptic determinants to the intracellular synaptic scaffold that controls the postsynaptic receptor content.
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Affiliation(s)
- Xin Zhou
- Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique Unite Mixte de Recherche 5310, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Lyon, France
| | - Camille Vachon
- Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique Unite Mixte de Recherche 5310, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Lyon, France
| | - Mélissa Cizeron
- Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique Unite Mixte de Recherche 5310, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Lyon, France
| | - Océane Romatif
- Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique Unite Mixte de Recherche 5310, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Lyon, France
| | - Hannes E Bülow
- Department of Genetics and Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY
| | - Maëlle Jospin
- Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique Unite Mixte de Recherche 5310, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Lyon, France
| | - Jean-Louis Bessereau
- Université de Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique Unite Mixte de Recherche 5310, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Lyon, France
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10
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Blood-brain barrier dysfunction as a potential therapeutic target for neurodegenerative disorders. Arch Pharm Res 2021; 44:487-498. [PMID: 34028650 DOI: 10.1007/s12272-021-01332-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 05/10/2021] [Indexed: 12/12/2022]
Abstract
The blood-brain barrier (BBB) is composed of specific tight junction proteins and transporters expressed on the lining of endothelial cells of the vasculature in the brain. The structural and functional integrity of the BBB is one of the most critical factors for maintaining brain homeostasis and is mainly regulated by complex interactions between various cell types, such as endothelial cells, pericytes, and astrocytes, which are shaped by their differential responses to changes in microenvironments. Alterations in these cellular components have been implicated in neurodegenerative disorders. Although it has long been considered that BBB dysfunction is a mere ramification of pathological phenomena, emerging evidence supports its critical role in the pathogenesis of various disorders. In epilepsy, heightened BBB permeability has been found to be associated with increased occurrence of spontaneous seizures. Additionally, exaggerated inflammatory responses significantly correlate with increased BBB permeability during healthy aging. Furthermore, it has been previously reported that BBB disruption can be an early marker for predicting cognitive impairment in the progression of Alzheimer's disease. We herein review a potential role of the major cellular components of the BBB, with a focus on the contribution of BBB disruption, in neurodegenerative disease progression.
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11
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Amran A, Pigatto L, Pocock R, Gopal S. Functions of the extracellular matrix in development: Lessons from Caenorhabditis elegans. Cell Signal 2021; 84:110006. [PMID: 33857577 DOI: 10.1016/j.cellsig.2021.110006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/04/2021] [Accepted: 04/05/2021] [Indexed: 12/30/2022]
Abstract
Cell-extracellular matrix interactions are crucial for the development of an organism from the earliest stages of embryogenesis. The main constituents of the extracellular matrix are collagens, laminins, proteoglycans and glycosaminoglycans that form a network of interactions. The extracellular matrix and its associated molecules provide developmental cues and structural support from the outside of cells during development. The complex nature of the extracellular matrix and its ability for continuous remodeling poses challenges when investigating extracellular matrix-based signaling during development. One way to address these challenges is to employ invertebrate models such as Caenorhabditis elegans, which are easy to genetically manipulate and have an invariant developmental program. C. elegans also expresses fewer extracellular matrix protein isoforms and exhibits reduced redundancy compared to mammalian models, thus providing a simpler platform for exploring development. This review summarizes our current understanding of how the extracellular matrix controls the development of neurons, muscles and the germline in C. elegans.
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Affiliation(s)
- Aqilah Amran
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria 3800, Australia
| | - Lara Pigatto
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria 3800, Australia
| | - Roger Pocock
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria 3800, Australia
| | - Sandeep Gopal
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, Victoria 3800, Australia; Department of Experimental Medical Science, Lund University, Lund, Sweden.
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12
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Goult BT. The Mechanical Basis of Memory - the MeshCODE Theory. Front Mol Neurosci 2021; 14:592951. [PMID: 33716664 PMCID: PMC7947202 DOI: 10.3389/fnmol.2021.592951] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 02/05/2021] [Indexed: 12/11/2022] Open
Abstract
One of the major unsolved mysteries of biological science concerns the question of where and in what form information is stored in the brain. I propose that memory is stored in the brain in a mechanically encoded binary format written into the conformations of proteins found in the cell-extracellular matrix (ECM) adhesions that organise each and every synapse. The MeshCODE framework outlined here represents a unifying theory of data storage in animals, providing read-write storage of both dynamic and persistent information in a binary format. Mechanosensitive proteins that contain force-dependent switches can store information persistently, which can be written or updated using small changes in mechanical force. These mechanosensitive proteins, such as talin, scaffold each synapse, creating a meshwork of switches that together form a code, the so-called MeshCODE. Large signalling complexes assemble on these scaffolds as a function of the switch patterns and these complexes would both stabilise the patterns and coordinate synaptic regulators to dynamically tune synaptic activity. Synaptic transmission and action potential spike trains would operate the cytoskeletal machinery to write and update the synaptic MeshCODEs, thereby propagating this coding throughout the organism. Based on established biophysical principles, such a mechanical basis for memory would provide a physical location for data storage in the brain, with the binary patterns, encoded in the information-storing mechanosensitive molecules in the synaptic scaffolds, and the complexes that form on them, representing the physical location of engrams. Furthermore, the conversion and storage of sensory and temporal inputs into a binary format would constitute an addressable read-write memory system, supporting the view of the mind as an organic supercomputer.
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Affiliation(s)
- Benjamin T. Goult
- School of Biosciences, University of Kent, Canterbury, United Kingdom
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13
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Imanishi A, Aoki Y, Kakehi M, Mori S, Takano T, Kubota Y, Kim HS, Shibata Y, Nishiwaki K. Genetic interactions among ADAMTS metalloproteases and basement membrane molecules in cell migration in Caenorhabditis elegans. PLoS One 2020; 15:e0240571. [PMID: 33264296 PMCID: PMC7710118 DOI: 10.1371/journal.pone.0240571] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/10/2020] [Indexed: 11/18/2022] Open
Abstract
During development of the Caenorhabditis elegans gonad, the gonadal leader cells, called distal tip cells (DTCs), migrate in a U-shaped pattern to form the U-shaped gonad arms. The ADAMTS (adisintegrin and metalloprotease with thrombospondin motifs) family metalloproteases MIG-17 and GON-1 are required for correct DTC migration. Mutations in mig-17 result in misshapen gonads due to the misdirected DTC migration, and mutations in gon-1 result in shortened and swollen gonads due to the premature termination of DTC migration. Although the phenotypes shown by mig-17 and gon-1 mutants are very different from one another, mutations that result in amino acid substitutions in the same basement membrane protein genes, emb-9/collagen IV α1, let-2/collagen IV α2 and fbl-1/fibulin-1, were identified as genetic suppressors of mig-17 and gon-1 mutants. To understand the roles shared by these two proteases, we examined the effects of the mig-17 suppressors on gon-1 and the effects of the gon-1 suppressors and enhancers on mig-17 gonadal defects. Some of the emb-9, let-2 and fbl-1 mutations suppressed both mig-17 and gon-1, whereas others acted only on mig-17 or gon-1. These results suggest that mig-17 and gon-1 have their specific functions as well as functions commonly shared between them for gonad formation. The levels of collagen IV accumulation in the DTC basement membrane were significantly higher in the gon-1 mutants as compared with wild type and were reduced to the wild-type levels when combined with suppressor mutations, but not with enhancer mutations, suggesting that the ability to reduce collagen IV levels is important for gon-1 suppression.
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Affiliation(s)
- Ayaka Imanishi
- Department of Bioscience, Kwansei Gakuin University, Sanda, Japan
| | - Yuma Aoki
- Department of Bioscience, Kwansei Gakuin University, Sanda, Japan
| | - Masaki Kakehi
- Department of Bioscience, Kwansei Gakuin University, Sanda, Japan
| | - Shunsuke Mori
- Department of Bioscience, Kwansei Gakuin University, Sanda, Japan
| | - Tomomi Takano
- Department of Bioscience, Kwansei Gakuin University, Sanda, Japan
| | - Yukihiko Kubota
- Department of Bioscience, Kwansei Gakuin University, Sanda, Japan
| | - Hon-Song Kim
- Department of Bioscience, Kwansei Gakuin University, Sanda, Japan
| | - Yukimasa Shibata
- Department of Bioscience, Kwansei Gakuin University, Sanda, Japan
| | - Kiyoji Nishiwaki
- Department of Bioscience, Kwansei Gakuin University, Sanda, Japan
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14
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Increased prolidase activity in Alzheimer's dementia: A case-control study. Asian J Psychiatr 2020; 53:102242. [PMID: 32590139 DOI: 10.1016/j.ajp.2020.102242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 06/15/2020] [Indexed: 02/08/2023]
Abstract
Prolidase enzyme, which catalyzes the final step in collagen metabolism can influence the cognitive functions through changes in extracellular matrix (ECM) resulting in altered synaptic connectivity in Alzheimer's disease (AD). In this study, it was found that the prolidase activity was significantly higher (p = 0.0016) in AD subjects (5.62 ± 2.05 U/ mL) than control group (4.45 ± 0.92 U/ mL). The increase was significant beginning at mild AD (p = 0.006) with an inverse correlation with HMSE scores (p = 0.0344), thus implying that prolidase mediated alterations in ECM may be associated with the cognitive deficits seen in AD.
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15
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Fan J, Ji T, Wang K, Huang J, Wang M, Manning L, Dong X, Shi Y, Zhang X, Shao Z, Colón-Ramos DA. A muscle-epidermis-glia signaling axis sustains synaptic specificity during allometric growth in Caenorhabditis elegans. eLife 2020; 9:55890. [PMID: 32255430 PMCID: PMC7164957 DOI: 10.7554/elife.55890] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/05/2020] [Indexed: 02/06/2023] Open
Abstract
Synaptic positions underlie precise circuit connectivity. Synaptic positions can be established during embryogenesis and sustained during growth. The mechanisms that sustain synaptic specificity during allometric growth are largely unknown. We performed forward genetic screens in C. elegans for regulators of this process and identified mig-17, a conserved ADAMTS metalloprotease. Proteomic mass spectrometry, cell biological and genetic studies demonstrate that MIG-17 is secreted from cells like muscles to regulate basement membrane proteins. In the nematode brain, the basement membrane does not directly contact synapses. Instead, muscle-derived basement membrane coats one side of the glia, while glia contact synapses on their other side. MIG-17 modifies the muscle-derived basement membrane to modulate epidermal-glial crosstalk and sustain glia location and morphology during growth. Glia position in turn sustains the synaptic pattern established during embryogenesis. Our findings uncover a muscle-epidermis-glia signaling axis that sustains synaptic specificity during the organism's allometric growth.
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Affiliation(s)
- Jiale Fan
- Department of Neurosurgery, the State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, the Institutes of Brain Science, and Zhongshan Hospital, Fudan University Shanghai, Shanghai, China
| | - Tingting Ji
- Department of Neurosurgery, the State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, the Institutes of Brain Science, and Zhongshan Hospital, Fudan University Shanghai, Shanghai, China
| | - Kai Wang
- Department of Neurosurgery, the State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, the Institutes of Brain Science, and Zhongshan Hospital, Fudan University Shanghai, Shanghai, China
| | - Jichang Huang
- State Key Laboratory of Genetic Engineering, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai, China
| | - Mengqing Wang
- Department of Neurosurgery, the State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, the Institutes of Brain Science, and Zhongshan Hospital, Fudan University Shanghai, Shanghai, China
| | - Laura Manning
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Neuroscience and Department of Cell Biology, Yale University School of Medicine, New Haven, United States
| | - Xiaohua Dong
- Department of Neurosurgery, the State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, the Institutes of Brain Science, and Zhongshan Hospital, Fudan University Shanghai, Shanghai, China
| | - Yanjun Shi
- Department of Neurosurgery, the State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, the Institutes of Brain Science, and Zhongshan Hospital, Fudan University Shanghai, Shanghai, China
| | - Xumin Zhang
- State Key Laboratory of Genetic Engineering, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai, China
| | - Zhiyong Shao
- Department of Neurosurgery, the State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, the Institutes of Brain Science, and Zhongshan Hospital, Fudan University Shanghai, Shanghai, China
| | - Daniel A Colón-Ramos
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Neuroscience and Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Instituto de Neurobiología, Recinto de Ciencias Médicas, Universidad de Puerto Rico, San Juan, Puerto Rico
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16
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Mitlöhner J, Kaushik R, Niekisch H, Blondiaux A, Gee CE, Happel MFK, Gundelfinger E, Dityatev A, Frischknecht R, Seidenbecher C. Dopamine Receptor Activation Modulates the Integrity of the Perisynaptic Extracellular Matrix at Excitatory Synapses. Cells 2020; 9:cells9020260. [PMID: 31972963 PMCID: PMC7073179 DOI: 10.3390/cells9020260] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/14/2020] [Accepted: 01/17/2020] [Indexed: 01/08/2023] Open
Abstract
In the brain, Hebbian-type and homeostatic forms of plasticity are affected by neuromodulators like dopamine (DA). Modifications of the perisynaptic extracellular matrix (ECM), which control the functions and mobility of synaptic receptors as well as the diffusion of transmitters and neuromodulators in the extracellular space, are crucial for the manifestation of plasticity. Mechanistic links between synaptic activation and ECM modifications are largely unknown. Here, we report that neuromodulation via D1-type DA receptors can induce targeted ECM proteolysis specifically at excitatory synapses of rat cortical neurons via proteases ADAMTS-4 and -5. We showed that receptor activation induces increased proteolysis of brevican (BC) and aggrecan, two major constituents of the adult ECM both in vivo and in vitro. ADAMTS immunoreactivity was detected near synapses, and shRNA-mediated knockdown reduced BC cleavage. We have outlined a molecular scenario of how synaptic activity and neuromodulation are linked to ECM rearrangements via increased cAMP levels, NMDA receptor activation, and intracellular calcium signaling.
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Affiliation(s)
- Jessica Mitlöhner
- Leibniz Institute for Neurobiology (LIN), Department of Neurochemistry and Molecular Biology, 39118 Magdeburg, Germany; (J.M.); (A.B.); (E.G.)
| | - Rahul Kaushik
- German Center for Neurodegenerative Diseases (DZNE), Molecular Neuroplasticity Group, 39120 Magdeburg, Germany;
- Center for Behavioral Brain Sciences (CBBS), 39120 Magdeburg, Germany
| | - Hartmut Niekisch
- Leibniz Institute for Neurobiology (LIN), Department of Systems Physiology of Learning, 39118 Magdeburg, Germany; (H.N.); (M.F.K.H.)
| | - Armand Blondiaux
- Leibniz Institute for Neurobiology (LIN), Department of Neurochemistry and Molecular Biology, 39118 Magdeburg, Germany; (J.M.); (A.B.); (E.G.)
| | - Christine E. Gee
- Center for Molecular Neurobiology Hamburg (ZMNH), Institute for Synaptic Physiology, 20251 Hamburg, Germany;
| | - Max F. K. Happel
- Leibniz Institute for Neurobiology (LIN), Department of Systems Physiology of Learning, 39118 Magdeburg, Germany; (H.N.); (M.F.K.H.)
| | - Eckart Gundelfinger
- Leibniz Institute for Neurobiology (LIN), Department of Neurochemistry and Molecular Biology, 39118 Magdeburg, Germany; (J.M.); (A.B.); (E.G.)
- Center for Behavioral Brain Sciences (CBBS), 39120 Magdeburg, Germany
- Otto-von-Guericke University, Medical Faculty, 39120 Magdeburg, Germany
| | - Alexander Dityatev
- German Center for Neurodegenerative Diseases (DZNE), Molecular Neuroplasticity Group, 39120 Magdeburg, Germany;
- Center for Behavioral Brain Sciences (CBBS), 39120 Magdeburg, Germany
- Otto-von-Guericke University, Medical Faculty, 39120 Magdeburg, Germany
- Correspondence: (A.D.); (R.F.); (C.S.); Tel.: +49-391 67-24526 (A.D.); +49-9131 85-28051 (R.F.); +49-391-6263-92401 (C.S.)
| | - Renato Frischknecht
- Leibniz Institute for Neurobiology (LIN), Department of Neurochemistry and Molecular Biology, 39118 Magdeburg, Germany; (J.M.); (A.B.); (E.G.)
- Center for Behavioral Brain Sciences (CBBS), 39120 Magdeburg, Germany
- Correspondence: (A.D.); (R.F.); (C.S.); Tel.: +49-391 67-24526 (A.D.); +49-9131 85-28051 (R.F.); +49-391-6263-92401 (C.S.)
| | - Constanze Seidenbecher
- Leibniz Institute for Neurobiology (LIN), Department of Neurochemistry and Molecular Biology, 39118 Magdeburg, Germany; (J.M.); (A.B.); (E.G.)
- Center for Behavioral Brain Sciences (CBBS), 39120 Magdeburg, Germany
- Otto-von-Guericke University, Medical Faculty, 39120 Magdeburg, Germany
- Correspondence: (A.D.); (R.F.); (C.S.); Tel.: +49-391 67-24526 (A.D.); +49-9131 85-28051 (R.F.); +49-391-6263-92401 (C.S.)
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17
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The Role of Tissue Inhibitors of Metalloproteinases in Organ Development and Regulation of ADAMTS Family Metalloproteinases in Caenorhabditis elegans. Genetics 2019; 212:523-535. [PMID: 30992386 DOI: 10.1534/genetics.119.301795] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/01/2019] [Indexed: 01/05/2023] Open
Abstract
Remodeling of the extracellular matrix supports tissue and organ development, by regulating cellular morphology and tissue integrity. However, proper extracellular matrix remodeling requires spatiotemporal regulation of extracellular metalloproteinase activity. Members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family, including MIG-17 and GON-1, are evolutionarily conserved, secreted, zinc-requiring metalloproteinases. Although these proteases are required for extracellular matrix remodeling during gonadogenesis in Caenorhabditis elegans, their in vivo regulatory mechanisms remain to be delineated. Therefore, we focused on the C. elegans tissue inhibitors of metalloproteinases (TIMPs), TIMP-1 and CRI-2 Analysis of the transcription and translation products for GFP/Venus fusions, with TIMP-1 or CRI-2, indicated that these inhibitors were secreted and localized to the basement membrane of gonads and the plasma membrane of germ cells. A timp-1 deletion mutant exhibited gonadal growth defects and sterility, and the phenotypes of this mutant were fully rescued by a TIMP-1::Venus construct, but not by a TIMP-1(C21S)::Venus mutant construct, in which the inhibitor coding sequence had been mutated. Moreover, genetic data suggested that TIMP-1 negatively regulates proteolysis of the α1 chain of type IV collagen. We also found that the loss-of-function observed for the mutants timp-1 and cri-2 involves a partial suppression of gonadal defects found for the mutants mig-17/ADAMTS and gon-1/ADAMTS, and that this suppression was canceled upon overexpression of gon-1 or mig-17, respectively. Based on these results, we propose that both TIMP-1 and CRI-2 act as inhibitors of MIG-17 and GON-1 ADAMTSs to regulate gonad development in a noncell-autonomous manner.
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18
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Kurshan PT, Shen K. Synaptogenic pathways. Curr Opin Neurobiol 2019; 57:156-162. [PMID: 30986749 DOI: 10.1016/j.conb.2019.03.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 03/11/2019] [Accepted: 03/13/2019] [Indexed: 11/30/2022]
Abstract
During synaptogenesis, presynaptic and postsynaptic assembly are driven by diverse molecular mechanisms, mediated by intrinsic as well as extrinsic factors. How these processes are initiated and coordinated are open questions. Synapse specificity, or synaptic partner selection, is widely understood to be determined by the trans-synaptic binding of cell adhesion molecules. However, in vivo evidence that cell adhesion molecules subsequently function to initiate synapse assembly, as initially proposed, is lacking. Here, we present a summary of our current understanding of synaptogenic pathways that mediate presynaptic and postsynaptic assembly and the coordination of these processes.
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Affiliation(s)
| | - Kang Shen
- Stanford University, Department of Biology, United States; Howard Hughes Medical Institute, United States
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19
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Shi Y, Li Q, Shao Z. Wnts Promote Synaptic Assembly Through T-Cell Specific Transcription Factors in Caenorhabditis elegans. Front Mol Neurosci 2018; 11:194. [PMID: 29962933 PMCID: PMC6013564 DOI: 10.3389/fnmol.2018.00194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/16/2018] [Indexed: 12/19/2022] Open
Abstract
Synapses are specialized neuronal connections essential for neuronal function. Defects in synaptic assembly or maintenance usually lead to various neurological disorders. Synaptic assembly is regulated by secreted molecules such as Wnts. Wnts are a large family of conserved glycosylated signaling molecules involved in many aspects of neural development and maintenance. However, the molecular mechanisms by which Wnts regulate synaptic assembly remain elusive due to the large number of ligands/receptors, the diversity of signaling cascades and the complexity of the nervous system. In this study, through genetic manipulation, we uncover that C. elegans Wnt-2 (CWN-2) is required for synaptic development. The CWN-2 signal is required during both embryonic and postembryonic development, in the nervous system and intestine, for promoting synaptic assembly. Furthermore, we provide genetic evidence for CWN-2 promoting synaptogenesis through the Frizzled receptor (FZD) CFZ-2, the Dishevelled (DVL) DSH-2, the β-catenin SYS-1 and the only T-cell specific transcription factor POP-1/TCF. Importantly, it is the first time to report the requirement of a TCF for presynaptic assembly. These findings expand our understanding of the synaptogenic mechanisms and may provide therapeutic insights into Wnt-related neurological disorders.
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Affiliation(s)
- Yanjun Shi
- Department of Neurology, State Key Laboratory of Medical Neurobiology and Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Qian Li
- Department of Neurology, State Key Laboratory of Medical Neurobiology and Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Zhiyong Shao
- Department of Neurology, State Key Laboratory of Medical Neurobiology and Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
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20
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Shilts J, Broadie K. Secreted tissue inhibitor of matrix metalloproteinase restricts trans-synaptic signaling to coordinate synaptogenesis. J Cell Sci 2017; 130:2344-2358. [PMID: 28576972 DOI: 10.1242/jcs.200808] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/29/2017] [Indexed: 12/20/2022] Open
Abstract
Synaptogenesis is coordinated by trans-synaptic signals that traverse the specialized synaptomatrix between presynaptic and postsynaptic cells. Matrix metalloproteinase (Mmp) activity sculpts this environment, balanced by secreted tissue inhibitors of Mmp (Timp). Here, we use the simplified Drosophila melanogaster matrix metalloproteome to test the consequences of eliminating all Timp regulatory control of Mmp activity at the neuromuscular junction (NMJ). Using in situ zymography, we find Timp limits Mmp activity at the NMJ terminal and shapes extracellular proteolytic dynamics surrounding individual synaptic boutons. In newly generated timp null mutants, NMJs exhibit architectural overelaboration with supernumerary synaptic boutons. With cell-targeted RNAi and rescue studies, we find that postsynaptic Timp limits presynaptic architecture. Functionally, timp null mutants exhibit compromised synaptic vesicle cycling, with activity that is lower in amplitude and fidelity. NMJ defects manifest in impaired locomotor function. Mechanistically, we find that Timp limits BMP trans-synaptic signaling and the downstream synapse-to-nucleus signal transduction. Pharmacologically restoring Mmp inhibition in timp null mutants corrects bone morphogenetic protein (BMP) signaling and synaptic properties. Genetically restoring BMP signaling in timp null mutants corrects NMJ structure and motor function. Thus, Timp inhibition of Mmp proteolytic activity restricts BMP trans-synaptic signaling to coordinate synaptogenesis.
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Affiliation(s)
- Jarrod Shilts
- Department of Biological Sciences, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37235, USA
| | - Kendal Broadie
- Department of Biological Sciences, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37235, USA
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21
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Khaspekov LG, Frumkina LE. Molecular mechanisms mediating involvement of glial cells in brain plastic remodeling in epilepsy. BIOCHEMISTRY (MOSCOW) 2017; 82:380-391. [DOI: 10.1134/s0006297917030178] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Abstract
While some autoimmune disorders remain extremely rare, others largely predominate the epidemiology of human autoimmunity. Notably, these include psoriasis, diabetes, vitiligo, thyroiditis, rheumatoid arthritis and multiple sclerosis. Thus, despite the quasi-infinite number of "self" antigens that could theoretically trigger autoimmune responses, only a limited set of antigens, referred here as superautoantigens, induce pathogenic adaptive responses. Several lines of evidence reviewed in this paper indicate that, irrespective of the targeted organ (e.g. thyroid, pancreas, joints, brain or skin), a significant proportion of superautoantigens are highly expressed in the synaptic compartment of the central nervous system (CNS). Such an observation applies notably for GAD65, AchR, ribonucleoproteins, heat shock proteins, collagen IV, laminin, tyrosine hydroxylase and the acetylcholinesterase domain of thyroglobulin. It is also argued that cognitive alterations have been described in a number of autoimmune disorders, including psoriasis, rheumatoid arthritis, lupus, Crohn's disease and autoimmune thyroiditis. Finally, the present paper points out that a great majority of the "incidental" autoimmune conditions notably triggered by neoplasms, vaccinations or microbial infections are targeting the synaptic or myelin compartments. On this basis, the concept of an immunological homunculus, proposed by Irun Cohen more than 25 years ago, is extended here in a model where physiological autoimmunity against brain superautoantigens confers both: i) a crucial evolutionary-determined advantage via cognition-promoting autoimmunity; and ii) a major evolutionary-determined vulnerability, leading to the emergence of autoimmune disorders in Homo sapiens. Moreover, in this theoretical framework, the so called co-development/co-evolution model, both the development (at the scale of an individual) and evolution (at the scale of species) of the antibody and T-cell repertoires are coupled to those of the neural repertoires (i.e. the distinct neuronal populations and synaptic circuits supporting cognitive and sensorimotor functions). Clinical implications and future experimental insights are also presented and discussed.
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Affiliation(s)
- Serge Nataf
- Bank of Tissues and Cells, Lyon University Hospital (Hospices Civils de Lyon), CarMeN Laboratory, INSERM 1060, INRA 1397, INSA Lyon, Université Claude Bernard Lyon-1, Lyon, F-69000, France
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23
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Jones RA, Reich CD, Dissanayake KN, Kristmundsdottir F, Findlater GS, Ribchester RR, Simmen MW, Gillingwater TH. NMJ-morph reveals principal components of synaptic morphology influencing structure-function relationships at the neuromuscular junction. Open Biol 2016; 6:160240. [PMID: 27927794 PMCID: PMC5204123 DOI: 10.1098/rsob.160240] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 11/09/2016] [Indexed: 01/10/2023] Open
Abstract
The ability to form synapses is one of the fundamental properties required by the mammalian nervous system to generate network connectivity. Structural and functional diversity among synaptic populations is a key hallmark of network diversity, and yet we know comparatively little about the morphological principles that govern variability in the size, shape and strength of synapses. Using the mouse neuromuscular junction (NMJ) as an experimentally accessible model synapse, we report on the development of a robust, standardized methodology to facilitate comparative morphometric analysis of synapses ('NMJ-morph'). We used NMJ-morph to generate baseline morphological reference data for 21 separate pre- and post-synaptic variables from 2160 individual NMJs belonging to nine anatomically distinct populations of synapses, revealing systematic differences in NMJ morphology between defined synaptic populations. Principal components analysis revealed that overall NMJ size and the degree of synaptic fragmentation, alongside pre-synaptic axon diameter, were the most critical parameters in defining synaptic morphology. 'Average' synaptic morphology was remarkably conserved between comparable synapses from the left and right sides of the body. Systematic differences in synaptic morphology predicted corresponding differences in synaptic function that were supported by physiological recordings, confirming the robust relationship between synaptic size and strength.
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Affiliation(s)
- Ross A Jones
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
- Centre for Integrative Physiology, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
- Anatomy, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
| | - Caitlan D Reich
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
- Centre for Integrative Physiology, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
- Anatomy, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
| | - Kosala N Dissanayake
- Centre for Integrative Physiology, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
| | - Fanney Kristmundsdottir
- Anatomy, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
| | - Gordon S Findlater
- Anatomy, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
| | - Richard R Ribchester
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
- Centre for Integrative Physiology, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
| | - Martin W Simmen
- Centre for Integrative Physiology, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
| | - Thomas H Gillingwater
- Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
- Centre for Integrative Physiology, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
- Anatomy, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Old Medical School, Teviot Place, Edinburgh EH8 9XD, UK
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24
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Kim SY, Porter BE, Friedman A, Kaufer D. A potential role for glia-derived extracellular matrix remodeling in postinjury epilepsy. J Neurosci Res 2016; 94:794-803. [PMID: 27265805 DOI: 10.1002/jnr.23758] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/07/2016] [Accepted: 04/07/2016] [Indexed: 01/04/2023]
Abstract
Head trauma and vascular injuries are known risk factors for acquired epilepsy. The sequence of events that lead from the initial injury to the development of epilepsy involves complex plastic changes and circuit rewiring. In-depth, comprehensive understanding of the epileptogenic process is critical for the identification of disease-modifying targets. Here we review the complex interactions of cellular and extracellular components that may promote epileptogenesis, with an emphasis on the role of astrocytes. Emerging evidence demonstrates that astrocytes promptly respond to brain damage and play a critical role in the development of postinjury epilepsy. Astrocytes have been shown to regulate extracellular matrix (ECM) remodeling, which can affect plasticity and stability of synapses and, in turn, contribute to the epileptogenic process. From these separate lines of evidence, we present a hypothesis suggesting a possible role for astrocyte-regulated remodeling of ECM and perineuronal nets, a specialized ECM structure around fast-spiking inhibitory interneurons, in the development and progression of posttraumatic epilepsies. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Soo Young Kim
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California
| | - Brenda E Porter
- Department of Neurology, Stanford University School of Medicine, Palo Alto, California
| | - Alon Friedman
- Departments of Physiology and Cell Biology, Cognitive and Brain Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Daniela Kaufer
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California.,Canadian Institute for Advanced Research Program in Child and Brain Development, Toronto, Ontario, Canada
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25
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Graffe M, Zenisek D, Taraska JW. A marginal band of microtubules transports and organizes mitochondria in retinal bipolar synaptic terminals. ACTA ACUST UNITED AC 2016; 146:109-17. [PMID: 26123197 PMCID: PMC4485018 DOI: 10.1085/jgp.201511396] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A band of microtubules ringing the retinal bipolar cell synaptic terminal may be crucial to supply and anchor the mitochondria required to sustain transmitter release. A set of bipolar cells in the retina of goldfish contains giant synaptic terminals that can be over 10 µm in diameter. Hundreds of thousands of synaptic vesicles fill these terminals and engage in continuous rounds of exocytosis. How the cytoskeleton and other organelles in these neurons are organized to control synaptic activity is unknown. Here, we used 3-D fluorescence and 3-D electron microscopy to visualize the complex subcellular architecture of these terminals. We discovered a thick band of microtubules that emerged from the axon to loop around the terminal periphery throughout the presynaptic space. This previously unknown microtubule structure associated with a substantial population of mitochondria in the synaptic terminal. Drugs that inhibit microtubule-based kinesin motors led to accumulation of mitochondria in the axon. We conclude that this prominent microtubule band is crucial to the transport and localization of mitochondria into the presynaptic space to provide the sustained energy necessary for continuous transmitter release in these giant synaptic terminals.
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Affiliation(s)
- Malkolm Graffe
- National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - David Zenisek
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510
| | - Justin W Taraska
- National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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