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The extracellular matrix: Focus on oligodendrocyte biology and targeting CSPGs for remyelination therapies. Glia 2018; 66:1809-1825. [DOI: 10.1002/glia.23333] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 03/06/2018] [Accepted: 03/06/2018] [Indexed: 12/31/2022]
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Minge D, Senkov O, Kaushik R, Herde MK, Tikhobrazova O, Wulff AB, Mironov A, van Kuppevelt TH, Oosterhof A, Kochlamazashvili G, Dityatev A, Henneberger C. Heparan Sulfates Support Pyramidal Cell Excitability, Synaptic Plasticity, and Context Discrimination. Cereb Cortex 2017; 27:903-918. [PMID: 28119345 PMCID: PMC5390399 DOI: 10.1093/cercor/bhx003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 12/04/2016] [Accepted: 01/04/2017] [Indexed: 02/06/2023] Open
Abstract
Heparan sulfate (HS) proteoglycans represent a major component of the extracellular matrix and are critical for brain development. However, their function in the mature brain remains to be characterized. Here, acute enzymatic digestion of HS side chains was used to uncover how HSs support hippocampal function in vitro and in vivo. We found that long-term potentiation (LTP) of synaptic transmission at CA3-CA1 Schaffer collateral synapses was impaired after removal of highly sulfated HSs with heparinase 1. This reduction was associated with decreased Ca2+ influx during LTP induction, which was the consequence of a reduced excitability of CA1 pyramidal neurons. At the subcellular level, heparinase treatment resulted in reorganization of the distal axon initial segment, as detected by a reduction in ankyrin G expression. In vivo, digestion of HSs impaired context discrimination in a fear conditioning paradigm and oscillatory network activity in the low theta band after fear conditioning. Thus, HSs maintain neuronal excitability and, as a consequence, support synaptic plasticity and learning.
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Affiliation(s)
- Daniel Minge
- Institute of Cellular Neurosciences, University of Bonn Medical School, 53105 Bonn, Germany
| | - Oleg Senkov
- German Center for Neurodegenerative Diseases (DZNE), 39120 Magdeburg, Germany
| | - Rahul Kaushik
- German Center for Neurodegenerative Diseases (DZNE), 39120 Magdeburg, Germany
| | - Michel K. Herde
- Institute of Cellular Neurosciences, University of Bonn Medical School, 53105 Bonn, Germany
| | - Olga Tikhobrazova
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, 16163 Genova, Italy
- Department of Neurotechnology, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia
| | - Andreas B. Wulff
- Institute of Cellular Neurosciences, University of Bonn Medical School, 53105 Bonn, Germany
| | - Andrey Mironov
- Department of Neurotechnology, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia
- Central Research Laboratory, Nizhny Novgorod State Medical Academy, 603005 Nizhny Novgorod, Russia
| | - Toin H. van Kuppevelt
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Arie Oosterhof
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Gaga Kochlamazashvili
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, 16163 Genova, Italy
- Department of Molecular Pharmacology and Cell Biology, Leibniz-Institut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Alexander Dityatev
- German Center for Neurodegenerative Diseases (DZNE), 39120 Magdeburg, Germany
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, 16163 Genova, Italy
- Department of Neurotechnology, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia
- Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, 39120 Magdeburg, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, University of Bonn Medical School, 53105 Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE), 53175 Bonn, Germany
- Institute of Neurology, University College London, London WC1N 3BG, UK
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Nakamura R, Nakamura F, Fukunaga S. Diverse functions of perlecan in central nervous system cells in vitro. Anim Sci J 2015; 86:904-11. [PMID: 25781054 DOI: 10.1111/asj.12376] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 11/11/2014] [Indexed: 11/30/2022]
Abstract
Therapeutic treatment targeting one cell type is considered ineffective in remedying any injury to the central nervous system (CNS). Perlecan, a multi-functional, heparan sulfate proteoglycan, shows diverse effects on distinct cell types, suggesting that it is one of the candidates that can augment the regenerative mechanisms in the injured CNS. Therefore, we examined the functions of perlecan in CNS cells in vitro by using perlecan purified from bovine kidney. Perlecan-coated cell culture plates, unlike their type I/III collagen-coated counterparts, did not inhibit the adhesion of neural stem/progenitor cells (NS/PCs) and neurons. The coated perlecan and the perlecan added to the culture medium suppressed astrocyte proliferation; however, perlecan added to the medium promoted NS/PC proliferation. Neurons were promoted to extend their neurites on the perlecan-coated substrate, and perlecan added to the medium also showed a similar effect. NS/PC proliferation and neurite extension is a major regenerative reaction in CNS injury, whereas excess proliferation of astrocytes cause hypertrophy of glial scars, which repels neurons. Our in vitro study suggests that perlecan is an attractive candidate to promote regenerative mechanisms and to suppress reactions that hamper regenerative processes in cases of CNS injury.
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Affiliation(s)
- Ryosuke Nakamura
- Laboratory of Animal By-Product Science, Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Fumio Nakamura
- Laboratory of Animal By-Product Science, Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Shigeharu Fukunaga
- Laboratory of Animal By-Product Science, Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
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Marcelo A, Bix G. The potential role of perlecan domain V as novel therapy in vascular dementia. Metab Brain Dis 2015; 30:1-5. [PMID: 24964971 DOI: 10.1007/s11011-014-9576-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/13/2014] [Indexed: 10/25/2022]
Abstract
Vascular dementia (VaD) is the second most common cause of dementia and leads to a decline in cognitive thinking via conditions that lead to blockage or reduced blood flow to the brain. It is a poorly understood disease, and the changes that occur are often linked to other types of dementia such as Alzheimer's disease. To date, there are no approved therapies or drugs to treat the symptoms of VaD, even though there is some evidence of drugs approved for Alzheimer's that might have some benefit in patients diagnosed with VaD. The altered blood flow that precedes VaD may result in compensatory mechanisms, such as angiogenesis, to increase blood flow in the brain. Angiogenesis, the process of new blood vessel formations from pre-existing ones, involves several pro-angiogenic factors such as vascular endothelial growth factor (VEGF) and is regulated by a variety of growth factors from neurons, astrocytes, and pericytes in the brain as well the extracellular matrix (ECM). The ECM highly regulates angiogenesis and other processes in the brain. One such ECM component is the heparan sulfate proteoglycan perlecan and its bioactive region, Domain V (DV). Here we discuss the potential role of DV as a novel therapy to treat VaD.
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Affiliation(s)
- Aileen Marcelo
- Sanders-Brown Center on Aging, Department of Anatomy and Neurobiology and Department of Neurology, University of Kentucky, 430 Sanders Brown Building, 800 S. Limestone Street, Lexington, KY, 40536-0230, USA
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Wright S, Parham C, Lee B, Clarke D, Auckland L, Johnston J, Lawrence AL, Dickeson SK, Santoro SA, Griswold-Prenner I, Bix G. Perlecan domain V inhibits α2 integrin-mediated amyloid-β neurotoxicity. Neurobiol Aging 2012; 33:1379-88. [DOI: 10.1016/j.neurobiolaging.2010.10.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 10/18/2010] [Accepted: 10/26/2010] [Indexed: 10/18/2022]
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Saini MG, Pinteaux E, Lee B, Bix GJ. Oxygen-glucose deprivation and interleukin-1α trigger the release of perlecan LG3 by cells of neurovascular unit. J Neurochem 2011; 119:760-71. [PMID: 21919908 DOI: 10.1111/j.1471-4159.2011.07484.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two of the main stresses faced by cells at the neurovascular unit (NVU) as an immediate result of cerebral ischemia are oxygen-glucose deprivation (OGD)/reperfusion and inflammatory stress caused by up regulation of IL-1. As a result of these stresses, perlecan, an important component of the NVU extracellular matrix, is highly proteolyzed. In this study, we describe that focal cerebral ischemia in rats results in increased generation of laminin globular domain 3 (LG3), the c-terminal bioactive fragment of perlecan. Further, in vitro study of the cells of the NVU was performed to locate the source of this increased perlecan-LG3. Neurons, astrocytes, brain endothelial cells and pericytes were exposed to OGD/reperfusion and IL-1α/β. It was observed that neurons and pericytes showed increased levels of LG3 during OGD in their culture media. During in vitro reperfusion, neurons, astrocytes and pericytes showed elevated levels of LG3, but only after exposure to brief durations of OGD. IL-1α and IL-1β treatment tended to have opposite effects on NVU cells. While IL-1α increased or had minimal to no effect on LG3 generation, high concentrations of IL-1β decreased it in most cells studied. Finally, LG3 was determined to be neuroprotective and anti-proliferative in brain endothelial cells, suggesting a possible role for the generation of LG3 in the ischemic brain.
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Affiliation(s)
- Maxim G Saini
- Department of Molecular and Cellular Medicine, Texas A&M College of Medicine, College Station, Texas 77843, USA
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Lee B, Clarke D, Al Ahmad A, Kahle M, Parham C, Auckland L, Shaw C, Fidanboylu M, Orr AW, Ogunshola O, Fertala A, Thomas SA, Bix GJ. Perlecan domain V is neuroprotective and proangiogenic following ischemic stroke in rodents. J Clin Invest 2011; 121:3005-23. [PMID: 21747167 DOI: 10.1172/jci46358] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 05/18/2011] [Indexed: 12/27/2022] Open
Abstract
Stroke is the leading cause of long-term disability and the third leading cause of death in the United States. While most research thus far has focused on acute stroke treatment and neuroprotection, the exploitation of endogenous brain self-repair mechanisms may also yield therapeutic strategies. Here, we describe a distinct type of stroke treatment, the naturally occurring extracellular matrix fragment of perlecan, domain V, which we found had neuroprotective properties and enhanced post-stroke angiogenesis, a key component of brain repair, in rodent models of stroke. In both rat and mouse models, Western blot analysis revealed elevated levels of perlecan domain V. When systemically administered 24 hours after stroke, domain V was well tolerated, reached infarct and peri-infarct brain vasculature, and restored stroke-affected motor function to baseline pre-stroke levels in these multiple stroke models in both mice and rats. Post-stroke domain V administration increased VEGF levels via a mechanism involving brain endothelial cell α5β1 integrin, and the subsequent neuroprotective and angiogenic actions of domain V were in turn mediated via VEGFR. These results suggest that perlecan domain V represents a promising approach for stroke treatment.
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Affiliation(s)
- Boyeon Lee
- Department of Molecular and Cellular Medicine, Texas A&M College of Medicine, College Station, Texas 77843, USA
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Wang Q, Yu S, Simonyi A, Sun GY, Sun AY. Kainic acid-mediated excitotoxicity as a model for neurodegeneration. Mol Neurobiol 2006; 31:3-16. [PMID: 15953808 DOI: 10.1385/mn:31:1-3:003] [Citation(s) in RCA: 268] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Accepted: 11/15/2004] [Indexed: 02/06/2023]
Abstract
Neuronal excitation involving the excitatory glutamate receptors is recognized as an important underlying mechanism in neurodegenerative disorders. Excitation resulting from stimulation of the ionotropic glutamate receptors is known to cause the increase in intracellular calcium and trigger calcium-dependent pathways that lead to neuronal apoptosis. Kainic acid (KA) is an agonist for a subtype of ionotropic glutamate receptor, and administration of KA has been shown to increase production of reactive oxygen species, mitochondrial dysfunction, and apoptosis in neurons in many regions of the brain, particularly in the hippocampal subregions of CA1 and CA3, and in the hilus of dentate gyrus (DG). Systemic injection of KA to rats also results in activation of glial cells and inflammatory responses typically found in neurodegenerative diseases. KA-induced selective vulnerability in the hippocampal neurons is related to the distribution and selective susceptibility of the AMPA/kainate receptors in the brain. Recent studies have demonstrated ability of KA to alter a number of intracellular activities, including accumulation of lipofuscin-like substances, induction of complement proteins, processing of amyloid precursor protein, and alteration of tau protein expression. These studies suggest that KA-induced excitotoxicity can be used as a model for elucidating mechanisms underlying oxidative stress and inflammation in neurodegenerative diseases. The focus of this review is to summarize studies demonstrating KA-induced excitotoxicity in the central nervous system and possible intervention by anti-oxidants.
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Affiliation(s)
- Qun Wang
- Department of Medical Pharmacology, University of Missouri School of Medicine, Columbia, MO, USA
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Huszthy PC, Svendsen A, Wilson JM, Kotin RM, Lønning PE, Bjerkvig R, Hoover F. Widespread dispersion of adeno-associated virus serotype 1 and adeno-associated virus serotype 6 vectors in the rat central nervous system and in human glioblastoma multiforme xenografts. Hum Gene Ther 2005; 16:381-92. [PMID: 15812233 DOI: 10.1089/hum.2005.16.381] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The transduction patterns of recombinant adeno-associated virus serotype 1 (AAV1) and serotype 6 (AAV6) vectors were assessed in human glioblastoma multiforme (GBM) cell lines, in human GBM biopsy spheroids, and in tumor xenografts growing in nude rat brains. All the cell lines tested (A172, D37, GaMg, HF66, and U373Mg) were found to be permissive to both AAV1 and AAV6 vectors, and thus displayed a transduction pattern similar to AAV2 vectors. For every cell line tested, the transduction efficiency displayed by AAV2 vectors was better than by isogenic and isopromoter AAV1 vectors. Transduction efficiency was dependent on the viral particle number used, suggesting that the receptors for these vectors are widely distributed in GBM tissues. Interestingly, AAV1, AAV2, and AAV6 vectors were able to infect and transduce the same cells when added simultaneously to monolayer cultures. Infection of human GBM biopsy spheroids with AAV1 and AAV6 vectors resulted in transgene expression both at the surface layers and in the core of the spheroids. Following injection of AAV1 and AAV6 vectors into human GBM biopsy xenografts growing in nude rat brains, reporter gene expression was seen both in the periphery as well as in the central regions of the tumors. When injected into the normal rat brain, both AAV1 and AAV6 vectors were found to transduce several central nervous system (CNS) regions. The presented results suggest a potential therapeutic role for AAV1 and AAV6 vectors in gene therapy for GBM and also for other CNS malignancies.
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Condic ML, Lemons ML. Extracellular matrix in spinal cord regeneration: getting beyond attraction and inhibition. Neuroreport 2002; 13:A37-48. [PMID: 11930141 DOI: 10.1097/00001756-200203040-00002] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- M L Condic
- Department of Neurobiology and Anatomy, University of Utah, School of Medicine, 50 N. Medical Drive, Salt Lake City, UT 84132, USA
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Ong WY, Hu CY, Soh YP, Lim TM, Pentchev PG, Patel SC. Neuronal localization of sterol regulatory element binding protein-1 in the rodent and primate brain: a light and electron microscopic immunocytochemical study. Neuroscience 2000; 97:143-53. [PMID: 10771346 DOI: 10.1016/s0306-4522(00)00031-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sterol regulatory element binding proteins are membrane-bound transcription factors that activate expression of several genes controlling cellular cholesterol and fatty acid homeostasis. The present study aimed to investigate the in vivo expression of sterol regulatory element binding protein-1 in the normal rodent and primate brain, and in the brain in Niemann-Pick type C disease mice. These mutant animals have lysosomal cholesterol accumulation and progressive neurodegeneration caused by an inactivating mutation of the NPC1 gene whose protein product functions in vesicular lipid trafficking. Western blot analysis of rat hippocampal homogenates with an affinity purified rabbit polyclonal antibody directed against an internal epitope of sterol regulatory element binding protein-1 identified a major 68,000 mol. wt protein consistent with the amino-terminal, transcriptionally active fragment of sterol regulatory element binding proteins-1. Immunocytochemically, this antibody revealed dense sterol regulatory element binding protein-1 staining of nuclei and light staining of the cytoplasm of cells in the neocortex and hippocampus in the rat, mouse and monkey brain. By electron microscopy of immunogold-labeled brain sections, these densely labeled cells were found to be neurons. In contrast, normal glial cells had little or no sterol regulatory element binding protein-1 immunoreactivity even at a developmental stage (postnatal day 9) which coincides with active myelination in the rat brain. Also, in contrast to the normal mouse brain, Niemann-Pick type C mice showed reduced staining of cortical and hippocampal neuronal nuclei. Since sterol regulatory element binding protein-1 has been shown to be a transcriptional regulator of fatty acid synthesis in vivo, the current findings of a predominantly neuronal nuclear expression of the 68,000 mol. wt transcriptionally active fragment of sterol regulatory element binding protein-1 highlights the established role of phospholipid metabolites and other fatty-acid containing lipids in neuronal signal transduction and other neuronal functions. Reduced sterol regulatory element binding protein-1 expression in neurons in Niemann-Pick type C may reflect a deficiency in fatty acid synthesis that could contribute to the neuronal dysfunction in this disorder.
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Affiliation(s)
- W Y Ong
- Department of Anatomy, National University of Singapore, Singapore, Singapore
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Abstract
The proteoglycans are multifunctional macromolecules composed of a core polypeptide and a variable number of glycosaminoglycan chains. The structural diversity and complexities of proteoglycan expression in the developing and adult Nervous System underlies the variety of biological functions that these molecules fulfill. Thus, in the Nervous System, proteoglycans regulate the structural organisation of the extracellular matrix, modulate growth factor activities and cellular adhesive and motility events, such as cell migration and axon outgrowth. This review summarises the evidences indicating that proteoglycans have an important role as modulators of neurite outgrowth and neuronal polarity. Special emphasis will be placed on those studies that have shown that proteoglycans of certain subtypes inhibit neurite extension either during the development and/or the regeneration of the vertebrate Central Nervous System.
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Affiliation(s)
- P Bovolenta
- Departamento de Neurobiología del Desarrollo, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Dr. Arce 37, 28002, Madrid, Spain.
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García de Yébenes E, Ho A, Damani T, Fillit H, Blum M. Regulation of the heparan sulfate proteoglycan, perlecan, by injury and interleukin-1alpha. J Neurochem 1999; 73:812-20. [PMID: 10428080 DOI: 10.1046/j.1471-4159.1999.0730812.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Perlecan is a specific proteoglycan that binds to amyloid precursor protein and beta-amyloid peptide, is present within amyloid deposits, and has been implicated in plaque formation. Because plaque formation is associated with local inflammation, we hypothesized that the mechanisms involved in brain inflammatory responses could influence perlecan biosynthesis. To test this hypothesis, we first studied perlecan regulation in mice after inflammation induced by a brain stab wound. Perlecan mRNA and immunoreactivity were both increased 3 days after injury. Interleukin-1alpha (IL-1alpha) is a cytokine induced after injury and plays an important role in inflammation. As such, IL-1alpha may be one of the factors participating in regulating perlecan synthesis. We thus studied perlecan regulation by IL-1alpha, in vivo. Regulation of perlecan mRNA by this cytokine was area-specific, showing up-regulation in hippocampus, whereas in striatum, perlecan mRNA was unchanged. To support this differential regulation of perlecan mRNA by IL-1alpha, basic fibroblast growth factor (bFGF), a growth factor also present in plaques, was studied in parallel. bFGF mRNA did not show any regional difference, being up-regulated in both hippocampus and striatum in vivo. In vitro, both astrocyte and microglia were immunoreactive for perlecan. Moreover, perlecan mRNA was increased in hippocampal glial cultures after IL-1alpha but not in striatal glia. These results show an increase in perlecan biosynthesis after injury and suggest a specific regulation of perlecan mRNA by IL-1alpha, which depends on brain area. Such regulation may have important implications in the understanding of regional brain variations in amyloid plaque formation.
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Affiliation(s)
- E García de Yébenes
- Fishberg Research Center for Neurobiology, Mount Sinai School of Medicine, New York, New York 10029, USA
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Donahue JE, Berzin TM, Rafii MS, Glass DJ, Yancopoulos GD, Fallon JR, Stopa EG. Agrin in Alzheimer's disease: altered solubility and abnormal distribution within microvasculature and brain parenchyma. Proc Natl Acad Sci U S A 1999; 96:6468-72. [PMID: 10339611 PMCID: PMC26905 DOI: 10.1073/pnas.96.11.6468] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Agrin is a heparan sulfate proteoglycan that is widely expressed in neurons and microvascular basal lamina in the rodent and avian central nervous system. Agrin induces the differentiation of nerve-muscle synapses, but its function in either normal or diseased brains is not known. Alzheimer's disease (AD) is characterized by loss of synapses, changes in microvascular architecture, and formation of neurofibrillary tangles and senile plaques. Here we have asked whether AD causes changes in the distribution and biochemical properties of agrin. Immunostaining of normal, aged human central nervous system revealed that agrin is expressed in neurons in multiple brain areas. Robust agrin immunoreactivity was observed uniformly in the microvascular basal lamina. In AD brains, agrin is highly concentrated in both diffuse and neuritic plaques as well as neurofibrillary tangles; neuronal expression of agrin also was observed. Furthermore, patients with AD had microvascular alterations characterized by thinning and fragmentation of the basal lamina. Detergent extraction and Western blotting showed that virtually all the agrin in normal brain is soluble in 1% SDS. In contrast, a large fraction of the agrin in AD brains is insoluble under these conditions, suggesting that it is tightly associated with beta-amyloid. Together, these data indicate that the agrin abnormalities observed in AD are closely linked to beta-amyloid deposition. These observations suggest that altered agrin expression in the microvasculature and the brain parenchyma contribute to the pathogenesis of AD.
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Affiliation(s)
- J E Donahue
- Department of Pathology (Neuropathology Division), Brown University, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903, USA
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