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Lenz M, Eichler A, Kruse P, Galanis C, Kleidonas D, Andrieux G, Boerries M, Jedlicka P, Müller U, Deller T, Vlachos A. The Amyloid Precursor Protein Regulates Synaptic Transmission at Medial Perforant Path Synapses. J Neurosci 2023; 43:5290-5304. [PMID: 37369586 PMCID: PMC10359033 DOI: 10.1523/jneurosci.1824-22.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 05/20/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
The perforant path provides the primary cortical excitatory input to the hippocampus. Because of its important role in information processing and coding, entorhinal projections to the dentate gyrus have been studied in considerable detail. Nevertheless, synaptic transmission between individual connected pairs of entorhinal stellate cells and dentate granule cells remains to be characterized. Here, we have used mouse organotypic entorhino-hippocampal tissue cultures of either sex, in which the entorhinal cortex (EC) to dentate granule cell (GC; EC-GC) projection is present, and EC-GC pairs can be studied using whole-cell patch-clamp recordings. By using cultures of wild-type mice, the properties of EC-GC synapses formed by afferents from the lateral and medial entorhinal cortex were compared, and differences in short-term plasticity were identified. As the perforant path is severely affected in Alzheimer's disease, we used tissue cultures of amyloid precursor protein (APP)-deficient mice to examine the role of APP at this synapse. APP deficiency altered excitatory neurotransmission at medial perforant path synapses, which was accompanied by transcriptomic and ultrastructural changes. Moreover, presynaptic but not postsynaptic APP deletion through the local injection of Cre-expressing adeno-associated viruses in conditional APPflox/flox tissue cultures increased the neurotransmission efficacy at perforant path synapses. In summary, these data suggest a physiological role for presynaptic APP at medial perforant path synapses that may be adversely affected under altered APP processing conditions.SIGNIFICANCE STATEMENT The hippocampus receives input from the entorhinal cortex via the perforant path. These projections to hippocampal dentate granule cells are of utmost importance for learning and memory formation. Although there is detailed knowledge about perforant path projections, the functional synaptic properties at the level of individual connected pairs of neurons are not well understood. In this study, we investigated the role of APP in mediating functional properties and transmission rules in individually connected neurons using paired whole-cell patch-clamp recordings and genetic tools in organotypic tissue cultures. Our results show that presynaptic APP expression limits excitatory neurotransmission via the perforant path, which could be compromised in pathologic conditions such as Alzheimer's disease.
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Affiliation(s)
- Maximilian Lenz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- Hannover Medical School, Institute of Neuroanatomy and Cell Biology, 30625 Hannover, Germany
| | - Amelie Eichler
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Pia Kruse
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Christos Galanis
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Dimitrios Kleidonas
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, 79104 Freiburg, Germany
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Geoffroy Andrieux
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Melanie Boerries
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- German Cancer Consortium, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Peter Jedlicka
- Interdisciplinary Centre for 3Rs in Animal Research, Faculty of Medicine, Justus-Liebig-University, 35392 Giessen, Germany
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
- Frankfurt Institute for Advanced Studies, 60438 Frankfurt am Main, Germany
| | - Ulrike Müller
- Institute of Pharmacy and Molecular Biotechnology, Functional Genomics, Ruprecht-Karls University Heidelberg, 69120 Heidelberg, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- Center for Basics in Neuromodulation, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
- Center BrainLinks-BrainTools, University of Freiburg, 79104 Freiburg, Germany
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2
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Ferrer-Raventós P, Puertollano-Martín D, Querol-Vilaseca M, Sánchez-Aced É, Valle-Tamayo N, Cervantes-Gonzalez A, Nuñez-Llaves R, Pegueroles J, Dols-Icardo O, Iulita MF, Aldecoa I, Molina-Porcel L, Sánchez-Valle R, Fortea J, Belbin O, Sirisi S, Lleó A. Amyloid precursor protein 𝛽CTF accumulates in synapses in sporadic and genetic forms of Alzheimer's disease. Neuropathol Appl Neurobiol 2023; 49:e12879. [PMID: 36702749 DOI: 10.1111/nan.12879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 12/21/2022] [Accepted: 01/21/2023] [Indexed: 01/28/2023]
Abstract
AIMS Amyloid precursor protein (APP) 𝛽-C-terminal fragment (𝛽CTF) may have a neurotoxic role in Alzheimer's disease (AD). 𝛽CTF accumulates in the brains of patients with sporadic (SAD) and genetic forms of AD. Synapses degenerate early during the pathogenesis of AD. We studied whether the 𝛽CTF accumulates in synapses in SAD, autosomal dominant AD (ADAD) and Down syndrome (DS). METHODS We used array tomography to determine APP at synapses in human AD tissue. We measured 𝛽CTF, A𝛽40, A𝛽42 and phosphorylated tau181 (p-tau181) concentrations in brain homogenates and synaptosomes of frontal and temporal cortex of SAD, ADAD, DS and controls. RESULTS APP colocalised with pre- and post-synaptic markers in human AD brains. APP 𝛽CTF was enriched in AD synaptosomes. CONCLUSIONS We demonstrate that 𝛽CTF accumulates in synapses in SAD, ADAD and DS. This finding might suggest a role for 𝛽CTF in synapse degeneration. Therapies aimed at mitigating 𝛽CTF accumulation could be potentially beneficial in AD.
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Affiliation(s)
- Paula Ferrer-Raventós
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - David Puertollano-Martín
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Marta Querol-Vilaseca
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Érika Sánchez-Aced
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Natalia Valle-Tamayo
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Alba Cervantes-Gonzalez
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Raúl Nuñez-Llaves
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Jordi Pegueroles
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Oriol Dols-Icardo
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Maria Florencia Iulita
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Iban Aldecoa
- Neurological Tissue Bank of the Biobanc-Hospital Clinic-IDIBAPS, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.,Department of Pathology, Biomedical Diagnostic Center, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain
| | - Laura Molina-Porcel
- Neurological Tissue Bank of the Biobanc-Hospital Clinic-IDIBAPS, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.,Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Service, Hospital Clínic de Barcelona, IDIBAPS, Barcelona, Spain
| | - Raquel Sánchez-Valle
- Neurological Tissue Bank of the Biobanc-Hospital Clinic-IDIBAPS, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.,Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Service, Hospital Clínic de Barcelona, IDIBAPS, Barcelona, Spain
| | - Juan Fortea
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Olivia Belbin
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Sònia Sirisi
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Alberto Lleó
- Department of Neurology, Sant Pau Memory Unit, Sant Pau Biomedical Research Institute, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
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Lin L, Petralia RS, Holtzclaw L, Wang YX, Abebe D, Hoffman DA. Alzheimer's disease/dementia-associated brain pathology in aging DPP6-KO mice. Neurobiol Dis 2022; 174:105887. [PMID: 36209950 PMCID: PMC9617781 DOI: 10.1016/j.nbd.2022.105887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/25/2022] [Accepted: 10/05/2022] [Indexed: 11/16/2022] Open
Abstract
We have previously reported that the single transmembrane protein Dipeptidyl Peptidase Like 6 (DPP6) impacts neuronal and synaptic development. DPP6-KO mice are impaired in hippocampal-dependent learning and memory and exhibit smaller brain size. Recently, we have described novel structures in hippocampal area CA1 in aging mice, apparently derived from degenerating presynaptic terminals, that are significantly more prevalent in DPP6-KO mice compared to WT mice of the same age and that these structures were observed earlier in development in DPP6-KO mice. These novel structures appear as clusters of large puncta that colocalize NeuN, synaptophysin, and chromogranin A, and also partially label for MAP2, amyloid β, APP, α-synuclein, and phosphorylated tau, with synapsin-1 and VGluT1 labeling on their periphery. In this current study, using immunofluorescence and electron microscopy, we confirm that both APP and amyloid β are prevalent in these structures; and we show with immunofluorescence the presence of similar structures in humans with Alzheimer's disease. Here we also found evidence that aging DPP6-KO mutants show additional changes related to Alzheimer's disease. We used in vivo MRI to show reduced size of the DPP6-KO brain and hippocampus. Aging DPP6-KO hippocampi contained fewer total neurons and greater neuron death and had diagnostic biomarkers of Alzheimer's disease present including accumulation of amyloid β and APP and increase in expression of hyper-phosphorylated tau. The amyloid β and phosphorylated tau pathologies were associated with neuroinflammation characterized by increases in microglia and astrocytes. And levels of proinflammatory or anti-inflammatory cytokines increased in aging DPP6-KO mice. We finally show that aging DPP6-KO mice display circadian dysfunction, a common symptom of Alzheimer's disease. Together these results indicate that aging DPP6-KO mice show symptoms of enhanced neurodegeneration reminiscent of dementia associated with a novel structure resulting from synapse loss and neuronal death. This study continues our laboratory's work in discerning the function of DPP6 and here provides compelling evidence of a direct role of DPP6 in Alzheimer's disease.
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Affiliation(s)
- Lin Lin
- Molecular Neurophysiology and Biophysics Section, Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ronald S Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lynne Holtzclaw
- Molecular Neurophysiology and Biophysics Section, Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Daniel Abebe
- Molecular Neurophysiology and Biophysics Section, Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dax A Hoffman
- Molecular Neurophysiology and Biophysics Section, Program in Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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Erdinger S, Amrein I, Back M, Ludewig S, Korte M, von Engelhardt J, Wolfer DP, Müller UC. Lack of APLP1 leads to subtle alterations in neuronal morphology but does not affect learning and memory. Front Mol Neurosci 2022; 15:1028836. [DOI: 10.3389/fnmol.2022.1028836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 10/11/2022] [Indexed: 11/13/2022] Open
Abstract
The amyloid precursor protein APP plays a crucial role in Alzheimer pathogenesis. Its physiological functions, however, are only beginning to be unraveled. APP belongs to a small gene family, including besides APP the closely related amyloid precursor-like proteins APLP1 and APLP2, that all constitute synaptic adhesion proteins. While APP and APLP2 are ubiquitously expressed, APLP1 is specific for the nervous system. Previous genetic studies, including combined knockouts of several family members, pointed towards a unique role for APLP1, as only APP/APLP1 double knockouts were viable. We now examined brain and neuronal morphology in APLP1 single knockout (KO) animals, that have to date not been studied in detail. Here, we report that APLP1-KO mice show normal spine density in hippocampal CA1 pyramidal cells and subtle alterations in dendritic complexity. Extracellular field recordings revealed normal basal synaptic transmission and no alterations in synaptic plasticity (LTP). Further, behavioral studies revealed in APLP1-KO mice a small deficit in motor function and reduced diurnal locomotor activity, while learning and memory were not affected by the loss of APLP1. In summary, our study indicates that APP family members serve both distinct and overlapping functions that need to be considered for therapeutic treatments of Alzheimer’s disease.
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5
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Gundelfinger ED, Karpova A, Pielot R, Garner CC, Kreutz MR. Organization of Presynaptic Autophagy-Related Processes. Front Synaptic Neurosci 2022; 14:829354. [PMID: 35368245 PMCID: PMC8968026 DOI: 10.3389/fnsyn.2022.829354] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 01/04/2022] [Indexed: 11/13/2022] Open
Abstract
Brain synapses pose special challenges on the quality control of their protein machineries as they are far away from the neuronal soma, display a high potential for plastic adaptation and have a high energy demand to fulfill their physiological tasks. This applies in particular to the presynaptic part where neurotransmitter is released from synaptic vesicles, which in turn have to be recycled and refilled in a complex membrane trafficking cycle. Pathways to remove outdated and damaged proteins include the ubiquitin-proteasome system acting in the cytoplasm as well as membrane-associated endolysosomal and the autophagy systems. Here we focus on the latter systems and review what is known about the spatial organization of autophagy and endolysomal processes within the presynapse. We provide an inventory of which components of these degradative systems were found to be present in presynaptic boutons and where they might be anchored to the presynaptic apparatus. We identify three presynaptic structures reported to interact with known constituents of membrane-based protein-degradation pathways and therefore may serve as docking stations. These are (i) scaffolding proteins of the cytomatrix at the active zone, such as Bassoon or Clarinet, (ii) the endocytic machinery localized mainly at the peri-active zone, and (iii) synaptic vesicles. Finally, we sketch scenarios, how presynaptic autophagic cargos are tagged and recruited and which cellular mechanisms may govern membrane-associated protein turnover in the presynapse.
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Affiliation(s)
- Eckart D. Gundelfinger
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Institute of Pharmacology and Toxicology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
- *Correspondence: Eckart D. Gundelfinger,
| | - Anna Karpova
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Rainer Pielot
- Institute of Pharmacology and Toxicology, Medical Faculty, Otto von Guericke University, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Craig C. Garner
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
- Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Michael R. Kreutz
- Research Group Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
- Center for Molecular Neurobiology (ZMNH), University Hospital Hamburg-Eppendorf, Hamburg, Germany
- German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
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Wang R, Chopra N, Nho K, Maloney B, Obukhov AG, Nelson PT, Counts SE, Lahiri DK. Human microRNA (miR-20b-5p) modulates Alzheimer's disease pathways and neuronal function, and a specific polymorphism close to the MIR20B gene influences Alzheimer's biomarkers. Mol Psychiatry 2022; 27:1256-1273. [PMID: 35087196 PMCID: PMC9054681 DOI: 10.1038/s41380-021-01351-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/30/2021] [Accepted: 10/04/2021] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder with loss of cognitive, executive, and other mental functions, and is the most common form of age-related dementia. Amyloid-β peptide (Aβ) contributes to the etiology and progression of the disease. Aβ is derived from the amyloid-β precursor protein (APP). Multiple microRNA (miRNA) species are also implicated in AD. We report that human hsa-miR20b-5p (miR-20b), produced from the MIR20B gene on Chromosome X, may play complex roles in AD pathogenesis, including Aβ regulation. Specifically, miR-20b-5p miRNA levels were altered in association with disease progression in three regions of the human brain: temporal neocortex, cerebellum, and posterior cingulate cortex. In cultured human neuronal cells, miR-20b-5p treatment interfered with calcium homeostasis, neurite outgrowth, and branchpoints. A single-nucleotide polymorphism (SNP) upstream of the MIR20B gene (rs13897515) associated with differences in levels of cerebrospinal fluid (CSF) Aβ1-42 and thickness of the entorhinal cortex. We located a miR-20b-5p binding site in the APP mRNA 3'-untranslated region (UTR), and treatment with miR-20b-5p reduced APP mRNA and protein levels. Network analysis of protein-protein interactions and gene coexpression revealed other important potential miR-20b-5p targets among AD-related proteins/genes. MiR-20b-5p, a miRNA that downregulated APP, was paradoxically associated with an increased risk for AD. However, miR-20b-5p also reduced, and the blockade of APP by siRNA likewise reduced calcium influx. As APP plays vital roles in neuronal health and does not exist solely to be the source of "pathogenic" Aβ, the molecular etiology of AD is likely to not just be a disease of "excess" but a disruption of delicate homeostasis.
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Affiliation(s)
- Ruizhi Wang
- Laboratory of Molecular Neurogenetics, Department of Psychiatry, Indiana Alzheimer's Disease Research Center, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Nipun Chopra
- Laboratory of Molecular Neurogenetics, Department of Psychiatry, Indiana Alzheimer's Disease Research Center, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- DePauw University, Greencastle, IN, 46135, USA
| | - Kwangsik Nho
- Radiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Bryan Maloney
- Laboratory of Molecular Neurogenetics, Department of Psychiatry, Indiana Alzheimer's Disease Research Center, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Alexander G Obukhov
- Anatomy, Cell Biology & Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Peter T Nelson
- Sanders-Brown Center on Aging, University of Kentucky, Kentucky Alzheimer's Disease Research Center, Lexington, KY, 40536, USA
| | - Scott E Counts
- Departments of Translational Neuroscience & Family Medicine, Michigan State University, Grand Rapids, and Michigan Alzheimer's Disease Research Center, Ann Arbor, MI, USA
| | - Debomoy K Lahiri
- Laboratory of Molecular Neurogenetics, Department of Psychiatry, Indiana Alzheimer's Disease Research Center, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Department of Medical & Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.
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Pelucchi S, Gardoni F, Di Luca M, Marcello E. Synaptic dysfunction in early phases of Alzheimer's Disease. HANDBOOK OF CLINICAL NEUROLOGY 2022; 184:417-438. [PMID: 35034752 DOI: 10.1016/b978-0-12-819410-2.00022-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The synapse is the locus of plasticity where short-term alterations in synaptic strength are converted to long-lasting memories. In addition to the presynaptic terminal and the postsynaptic compartment, a more holistic view of the synapse includes the astrocytes and the extracellular matrix to form a tetrapartite synapse. All these four elements contribute to synapse health and are crucial for synaptic plasticity events and, thereby, for learning and memory processes. Synaptic dysfunction is a common pathogenic trait of several brain disorders. In Alzheimer's Disease, the degeneration of synapses can be detected at the early stages of pathology progression before neuronal degeneration, supporting the hypothesis that synaptic failure is a major determinant of the disease. The synapse is the place where amyloid-β peptides are generated and is the target of the toxic amyloid-β oligomers. All the elements constituting the tetrapartite synapse are altered in Alzheimer's Disease and can synergistically contribute to synaptic dysfunction. Moreover, the two main hallmarks of Alzheimer's Disease, i.e., amyloid-β and tau, act in concert to cause synaptic deficits. Deciphering the mechanisms underlying synaptic dysfunction is relevant for the development of the next-generation therapeutic strategies aimed at modifying the disease progression.
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Affiliation(s)
- Silvia Pelucchi
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Fabrizio Gardoni
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Monica Di Luca
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy
| | - Elena Marcello
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan, Italy.
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8
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Di Paolo A, Garat J, Eastman G, Farias J, Dajas-Bailador F, Smircich P, Sotelo-Silveira JR. Functional Genomics of Axons and Synapses to Understand Neurodegenerative Diseases. Front Cell Neurosci 2021; 15:686722. [PMID: 34248504 PMCID: PMC8267896 DOI: 10.3389/fncel.2021.686722] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 06/02/2021] [Indexed: 01/02/2023] Open
Abstract
Functional genomics studies through transcriptomics, translatomics and proteomics have become increasingly important tools to understand the molecular basis of biological systems in the last decade. In most cases, when these approaches are applied to the nervous system, they are centered in cell bodies or somatodendritic compartments, as these are easier to isolate and, at least in vitro, contain most of the mRNA and proteins present in all neuronal compartments. However, key functional processes and many neuronal disorders are initiated by changes occurring far away from cell bodies, particularly in axons (axopathologies) and synapses (synaptopathies). Both neuronal compartments contain specific RNAs and proteins, which are known to vary depending on their anatomical distribution, developmental stage and function, and thus form the complex network of molecular pathways required for neuron connectivity. Modifications in these components due to metabolic, environmental, and/or genetic issues could trigger or exacerbate a neuronal disease. For this reason, detailed profiling and functional understanding of the precise changes in these compartments may thus yield new insights into the still intractable molecular basis of most neuronal disorders. In the case of synaptic dysfunctions or synaptopathies, they contribute to dozens of diseases in the human brain including neurodevelopmental (i.e., autism, Down syndrome, and epilepsy) as well as neurodegenerative disorders (i.e., Alzheimer's and Parkinson's diseases). Histological, biochemical, cellular, and general molecular biology techniques have been key in understanding these pathologies. Now, the growing number of omics approaches can add significant extra information at a high and wide resolution level and, used effectively, can lead to novel and insightful interpretations of the biological processes at play. This review describes current approaches that use transcriptomics, translatomics and proteomic related methods to analyze the axon and presynaptic elements, focusing on the relationship that axon and synapses have with neurodegenerative diseases.
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Affiliation(s)
- Andres Di Paolo
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
- Departamento de Proteínas y Ácidos Nucleicos, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Joaquin Garat
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Guillermo Eastman
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Joaquina Farias
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
- Polo de Desarrollo Universitario “Espacio de Biología Vegetal del Noreste”, Centro Universitario Regional Noreste, Universidad de la República (UdelaR), Tacuarembó, Uruguay
| | - Federico Dajas-Bailador
- School of Life Sciences, Medical School Building, University of Nottingham, Nottingham, United Kingdom
| | - Pablo Smircich
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
- Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Universidad de la República (UdelaR), Montevideo, Uruguay
| | - José Roberto Sotelo-Silveira
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
- Departamento de Biología Celular y Molecular, Facultad de Ciencias, Universidad de la República (UdelaR), Montevideo, Uruguay
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9
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Augustin V, Kins S. Fe65: A Scaffolding Protein of Actin Regulators. Cells 2021; 10:cells10071599. [PMID: 34202290 PMCID: PMC8304848 DOI: 10.3390/cells10071599] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 01/19/2023] Open
Abstract
The scaffolding protein family Fe65, composed of Fe65, Fe65L1, and Fe65L2, was identified as an interaction partner of the amyloid precursor protein (APP), which plays a key function in Alzheimer’s disease. All three Fe65 family members possess three highly conserved interaction domains, forming complexes with diverse binding partners that can be assigned to different cellular functions, such as transactivation of genes in the nucleus, modulation of calcium homeostasis and lipid metabolism, and regulation of the actin cytoskeleton. In this article, we rule out putative new intracellular signaling mechanisms of the APP-interacting protein Fe65 in the regulation of actin cytoskeleton dynamics in the context of various neuronal functions, such as cell migration, neurite outgrowth, and synaptic plasticity.
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10
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Tkatchenko TV, Tkatchenko AV. Genome-wide analysis of retinal transcriptome reveals common genetic network underlying perception of contrast and optical defocus detection. BMC Med Genomics 2021; 14:153. [PMID: 34107987 PMCID: PMC8190860 DOI: 10.1186/s12920-021-01005-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 06/04/2021] [Indexed: 12/12/2022] Open
Abstract
Background Refractive eye development is regulated by optical defocus in a process of emmetropization. Excessive exposure to negative optical defocus often leads to the development of myopia. However, it is still largely unknown how optical defocus is detected by the retina. Methods Here, we used genome-wide RNA-sequencing to conduct analysis of the retinal gene expression network underlying contrast perception and refractive eye development. Results We report that the genetic network subserving contrast perception plays an important role in optical defocus detection and emmetropization. Our results demonstrate an interaction between contrast perception, the retinal circadian clock pathway and the signaling pathway underlying optical defocus detection. We also observe that the relative majority of genes causing human myopia are involved in the processing of optical defocus. Conclusions Together, our results support the hypothesis that optical defocus is perceived by the retina using contrast as a proxy and provide new insights into molecular signaling underlying refractive eye development. Supplementary Information The online version contains supplementary material available at 10.1186/s12920-021-01005-x.
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Affiliation(s)
| | - Andrei V Tkatchenko
- Department of Ophthalmology, Columbia University, New York, NY, USA. .,Department of Pathology and Cell Biology, Columbia University, New York, NY, USA. .,Edward S. Harkness Eye Institute, Research Annex Room 415, 635 W. 165th Street, New York, NY, 10032, USA.
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11
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Nakano M, Mitsuishi Y, Liu L, Watanabe N, Hibino E, Hata S, Saito T, Saido TC, Murayama S, Kasuga K, Ikeuchi T, Suzuki T, Nishimura M. Extracellular Release of ILEI/FAM3C and Amyloid-β Is Associated with the Activation of Distinct Synapse Subpopulations. J Alzheimers Dis 2021; 80:159-174. [PMID: 33492290 DOI: 10.3233/jad-201174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Brain amyloid-β (Aβ) peptide is released into the interstitial fluid (ISF) in a neuronal activity-dependent manner, and Aβ deposition in Alzheimer's disease (AD) is linked to baseline neuronal activity. Although the intrinsic mechanism for Aβ generation remains to be elucidated, interleukin-like epithelial-mesenchymal transition inducer (ILEI) is a candidate for an endogenous Aβ suppressor. OBJECTIVE This study aimed to access the mechanism underlying ILEI secretion and its effect on Aβ production in the brain. METHODS ILEI and Aβ levels in the cerebral cortex were monitored using a newly developed ILEI-specific ELISA and in vivo microdialysis in mutant human Aβ precursor protein-knockin mice. ILEI levels in autopsied brains and cerebrospinal fluid (CSF) were measured using ELISA. RESULTS Extracellular release of ILEI and Aβ was dependent on neuronal activation and specifically on tetanus toxin-sensitive exocytosis of synaptic vesicles. However, simultaneous monitoring of extracellular ILEI and Aβ revealed that a spontaneous fluctuation of ILEI levels appeared to inversely mirror that of Aβ levels. Selective activation and inhibition of synaptic receptors differentially altered these levels. The evoked activation of AMPA-type receptors resulted in opposing changes to ILEI and Aβ levels. Brain ILEI levels were selectively decreased in AD. CSF ILEI concentration correlated with that of Aβ and were reduced in AD and mild cognitive impairment. CONCLUSION ILEI and Aβ are released from distinct subpopulations of synaptic terminals in an activity-dependent manner, and ILEI negatively regulates Aβ production in specific synapse types. CSF ILEI might represent a surrogate marker for the accumulation of brain Aβ.
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Affiliation(s)
- Masaki Nakano
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga, Japan
| | - Yachiyo Mitsuishi
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga, Japan
| | - Lei Liu
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga, Japan
| | - Naoki Watanabe
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga, Japan
| | - Emi Hibino
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga, Japan
| | - Saori Hata
- Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Hokkaido, Japan.,Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Takashi Saito
- Laboratory for Proteolytic Neuroscience, RIKEN Brain Science Institute, Saitama, Japan.,Department of Neurocognitive Science, Institute of Brain Science, Nagoya City University Graduate School of Medical Science, Nagoya, Japan
| | - Takaomi C Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Brain Science Institute, Saitama, Japan
| | - Shigeo Murayama
- Department of Neurology and Neuropathology (the Brain Bank for Aging Research), Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo, Japan
| | - Kensaku Kasuga
- Department of Molecular Genetics, Brain Research Institute, Niigata University, Niigata, Japan
| | - Takeshi Ikeuchi
- Department of Molecular Genetics, Brain Research Institute, Niigata University, Niigata, Japan
| | - Toshiharu Suzuki
- Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Hokkaido, Japan
| | - Masaki Nishimura
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Shiga, Japan
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12
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Lin L, Petralia RS, Lake R, Wang YX, Hoffman DA. A novel structure associated with aging is augmented in the DPP6-KO mouse brain. Acta Neuropathol Commun 2020; 8:197. [PMID: 33225987 PMCID: PMC7682109 DOI: 10.1186/s40478-020-01065-7] [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: 10/13/2020] [Accepted: 10/17/2020] [Indexed: 01/05/2023] Open
Abstract
In addition to its role as an auxiliary subunit of A-type voltage-gated K+ channels, we have previously reported that the single transmembrane protein Dipeptidyl Peptidase Like 6 (DPP6) impacts neuronal and synaptic development. DPP6-KO mice are impaired in hippocampal-dependent learning and memory and exhibit smaller brain size. Using immunofluorescence and electron microscopy, we report here a novel structure in hippocampal area CA1 that was significantly more prevalent in aging DPP6-KO mice compared to WT mice of the same age and that these structures were observed earlier in development in DPP6-KO mice. These novel structures appeared as clusters of large puncta that colocalized NeuN, synaptophysin, and chromogranin A. They also partially labeled for MAP2, and with synapsin-1 and VGluT1 labeling on their periphery. Electron microscopy revealed that these structures are abnormal, enlarged presynaptic swellings filled with mainly fibrous material with occasional peripheral, presynaptic active zones forming synapses. Immunofluorescence imaging then showed that a number of markers for aging and especially Alzheimer’s disease were found as higher levels in these novel structures in aging DPP6-KO mice compared to WT. Together these results indicate that aging DPP6-KO mice have increased numbers of novel, abnormal presynaptic structures associated with several markers of Alzheimer’s disease.
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13
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Chatzistavraki M, Papazafiri P, Efthimiopoulos S. Amyloid-β Protein Precursor Regulates Depolarization-Induced Calcium-Mediated Synaptic Signaling in Brain Slices. J Alzheimers Dis 2020; 76:1121-1133. [PMID: 32597808 DOI: 10.3233/jad-200290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Coordinated calcium influx upon neuronal depolarization activates pathways that phosphorylate CaMKII, ERKs, and the transcription factor CREB and, therefore, expression of pro-survival and neuroprotective genes. Recent evidence indicates that amyloid-β protein precursor (AβPP) is trafficked to synapses and promotes their formation. At the synapse, AβPP interacts with synaptic proteins involved in vesicle exocytosis and affects calcium channel function. OBJECTIVE Herein, we examined the role of AβPP in depolarization-induced calcium-mediated signaling using acute cerebral slices from wild-type C57bl/6 mice and AβPP-/- C57bl/6 mice. METHODS Depolarization of acute cerebral slices from wild-type C57bl/6 and AβPP-/- C57bl/6 mice was used to induce synaptic signaling. Protein levels were examined by western blot and calcium dynamics were assessed using primary neuronal cultures. RESULTS In the absence of AβPP, decreased pCaMKII and pERKs levels were observed. This decrease was sensitive to the inhibition of N- and P/Q-type Voltage Gated Calcium Channels (N- and P/Q-VGCCs) by ω-conotoxin GVIA and ω-conotoxin MVIIC, respectively, but not to inhibition of L-type VGCCs by nifedipine. However, the absence of AβPP did not result in a statistically significant decrease of pCREB, which is a known substrate of pERKs. Finally, using calcium imaging, we found that down regulation of AβPP in cortical neurons results in a decreased response to depolarization and altered kinetics of calcium response. CONCLUSION AβPP regulates synaptic activity-mediated neuronal signaling by affecting N- and P/Q-VGCCs.
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Affiliation(s)
- Maria Chatzistavraki
- Department of Biology, Division of Animal and Human Physiology, National and Kapodistrian University of Athens, Panepistimiopolis, Ilisia, Greece
| | - Panagiota Papazafiri
- Department of Biology, Division of Animal and Human Physiology, National and Kapodistrian University of Athens, Panepistimiopolis, Ilisia, Greece
| | - Spiros Efthimiopoulos
- Department of Biology, Division of Animal and Human Physiology, National and Kapodistrian University of Athens, Panepistimiopolis, Ilisia, Greece
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14
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Banote RK, Chebli J, Şatır TM, Varshney GK, Camacho R, Ledin J, Burgess SM, Abramsson A, Zetterberg H. Amyloid precursor protein-b facilitates cell adhesion during early development in zebrafish. Sci Rep 2020; 10:10127. [PMID: 32576936 PMCID: PMC7311384 DOI: 10.1038/s41598-020-66584-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 05/21/2020] [Indexed: 01/05/2023] Open
Abstract
Understanding the biological function of amyloid beta (Aβ) precursor protein (APP) beyond its role in Alzheimer's disease is emerging. Yet, its function during embryonic development is poorly understood. The zebrafish APP orthologue, Appb, is strongly expressed during early development but thus far has only been studied via morpholino-mediated knockdown. Zebrafish enables analysis of cellular processes in an ontogenic context, which is limited in many other vertebrates. We characterized zebrafish carrying a homozygous mutation that introduces a premature stop in exon 2 of the appb gene. We report that appb mutants are significantly smaller until 2 dpf and display perturbed enveloping layer (EVL) integrity and cell protrusions at the blastula stage. Moreover, appb mutants surviving beyond 48 hpf exhibited no behavioral defects at 6 dpf and developed into healthy and fertile adults. The expression of the app family member, appa, was also found to be altered in appb mutants. Taken together, we show that appb is involved in the initial development of zebrafish by supporting the integrity of the EVL, likely by mediating cell adhesion properties. The loss of Appb might then be compensated for by other app family members to maintain normal development.
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Affiliation(s)
- Rakesh Kumar Banote
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, University of Gothenburg, S-41345, Gothenburg, Sweden.,Cellectricon AB, Neongatan 4B, SE-431 53, Mölndal, Sweden
| | - Jasmine Chebli
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, University of Gothenburg, S-41345, Gothenburg, Sweden
| | - Tuğçe Munise Şatır
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, University of Gothenburg, S-41345, Gothenburg, Sweden
| | - Gaurav K Varshney
- Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA.,Genes & Human Disease Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Rafael Camacho
- Centre for Cellular Imaging, Core Facilities, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Johan Ledin
- Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA.,Department of Organismal Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Shawn M Burgess
- Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Alexandra Abramsson
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, University of Gothenburg, S-41345, Gothenburg, Sweden.
| | - Henrik Zetterberg
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, University of Gothenburg, S-41345, Gothenburg, Sweden.,Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.,Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, WC1N3BG, United Kingdom.,UK Dementia Research Institute, London, WC1N3BG, United Kingdom
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15
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Dar NJ, Glazner GW. Deciphering the neuroprotective and neurogenic potential of soluble amyloid precursor protein alpha (sAPPα). Cell Mol Life Sci 2020; 77:2315-2330. [PMID: 31960113 PMCID: PMC11105086 DOI: 10.1007/s00018-019-03404-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 11/21/2019] [Accepted: 11/28/2019] [Indexed: 12/25/2022]
Abstract
Amyloid precursor protein (APP) is a transmembrane protein expressed largely within the central nervous system. Upon cleavage, it does not produce the toxic amyloid peptide (Aβ) only, which is involved in neurodegenerative progressions but via a non-amyloidogenic pathway it is metabolized to produce a soluble fragment (sAPPα) through α-secretase. While a lot of studies are focusing on the role played by APP in the pathogenesis of Alzheimer's disease, sAPPα is reported to have numerous neuroprotective effects and it is being suggested as a candidate with possible therapeutic potential against Alzheimer's disease. However, the mechanisms through which sAPPα precisely works remain elusive. We have presented a comprehensive review of how sAPPα is regulating the neuroprotective effects in different biological models. Moreover, we have focused on the role of sAPPα during different developmental stages of the brain, neurogenic microenvironment in the brain and how this metabolite of APP is regulating the neurogenesis which is regarded as a compelling approach to ameliorate the impaired learning and memory deficits in dementia and diseases like Alzheimer's disease. sAPPα exerts beneficial physiological, biochemical and behavioral effects mitigating the detrimental effects of neurotoxic compounds. It has shown to increase the proliferation rate of numerous cell types and promised the synaptogenesis, neurite outgrowth, cell survival and cell adhesion. Taken together, we believe that further studies are warranted to investigate the exact mechanism of action so that sAPPα could be developed as a novel therapeutic target against neuronal deficits.
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Affiliation(s)
- Nawab John Dar
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada
- St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, R2H 2A6, Canada
| | - Gordon W Glazner
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada.
- St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, R2H 2A6, Canada.
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16
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Barthet G, Mulle C. Presynaptic failure in Alzheimer's disease. Prog Neurobiol 2020; 194:101801. [PMID: 32428558 DOI: 10.1016/j.pneurobio.2020.101801] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/24/2020] [Accepted: 04/03/2020] [Indexed: 12/14/2022]
Abstract
Synaptic loss is the best correlate of cognitive deficits in Alzheimer's disease (AD). Extensive experimental evidence also indicates alterations of synaptic properties at the early stages of disease progression, before synapse loss and neuronal degeneration. A majority of studies in mouse models of AD have focused on post-synaptic mechanisms, including impairment of long-term plasticity, spine structure and glutamate receptor-mediated transmission. Here we review the literature indicating that the synaptic pathology in AD includes a strong presynaptic component. We describe the evidence indicating presynaptic physiological functions of the major molecular players in AD. These include the amyloid precursor protein (APP) and the two presenilin (PS) paralogs PS1 or PS2, genetically linked to the early-onset form of AD, in addition to tau which accumulates in a pathological form in the AD brain. Three main mechanisms participating in presynaptic functions are highlighted. APP fragments bind to presynaptic receptors (e.g. nAChRs and GABAB receptors), presenilins control Ca2+ homeostasis and Ca2+-sensors, and tau regulates the localization of presynaptic molecules and synaptic vesicles. We then discuss how impairment of these presynaptic physiological functions can explain or forecast the hallmarks of synaptic impairment and associated dysfunction of neuronal circuits in AD. Beyond the physiological roles of the AD-related proteins, studies in AD brains also support preferential presynaptic alteration. This review features presynaptic failure as a strong component of pathological mechanisms in AD.
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Affiliation(s)
- Gael Barthet
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, France
| | - Christophe Mulle
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, France.
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17
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Perdigão C, Barata MA, Araújo MN, Mirfakhar FS, Castanheira J, Guimas Almeida C. Intracellular Trafficking Mechanisms of Synaptic Dysfunction in Alzheimer's Disease. Front Cell Neurosci 2020; 14:72. [PMID: 32362813 PMCID: PMC7180223 DOI: 10.3389/fncel.2020.00072] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 03/12/2020] [Indexed: 12/15/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common neurodegenerative disease characterized by progressive memory loss. Although AD neuropathological hallmarks are extracellular amyloid plaques and intracellular tau tangles, the best correlate of disease progression is synapse loss. What causes synapse loss has been the focus of several researchers in the AD field. Synapses become dysfunctional before plaques and tangles form. Studies based on early-onset familial AD (eFAD) models have supported that synaptic transmission is depressed by β-amyloid (Aβ) triggered mechanisms. Since eFAD is rare, affecting only 1% of patients, research has shifted to the study of the most common late-onset AD (LOAD). Intracellular trafficking has emerged as one of the pathways of LOAD genes. Few studies have assessed the impact of trafficking LOAD genes on synapse dysfunction. Since endocytic traffic is essential for synaptic function, we reviewed Aβ-dependent and independent mechanisms of the earliest synaptic dysfunction in AD. We have focused on the role of intraneuronal and secreted Aβ oligomers, highlighting the dysfunction of endocytic trafficking as an Aβ-dependent mechanism of synapse dysfunction in AD. Here, we reviewed the LOAD trafficking genes APOE4, ABCA7, BIN1, CD2AP, PICALM, EPH1A, and SORL1, for which there is a synaptic link. We conclude that in eFAD and LOAD, the earliest synaptic dysfunctions are characterized by disruptions of the presynaptic vesicle exo- and endocytosis and of postsynaptic glutamate receptor endocytosis. While in eFAD synapse dysfunction seems to be triggered by Aβ, in LOAD, there might be a direct synaptic disruption by LOAD trafficking genes. To identify promising therapeutic targets and biomarkers of the earliest synaptic dysfunction in AD, it will be necessary to join efforts in further dissecting the mechanisms used by Aβ and by LOAD genes to disrupt synapses.
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Affiliation(s)
- Catarina Perdigão
- Laboratory Neuronal Trafficking in Aging, CEDOC Chronic Diseases Research Center, NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Mariana A Barata
- Laboratory Neuronal Trafficking in Aging, CEDOC Chronic Diseases Research Center, NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Margarida N Araújo
- Laboratory Neuronal Trafficking in Aging, CEDOC Chronic Diseases Research Center, NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Farzaneh S Mirfakhar
- Laboratory Neuronal Trafficking in Aging, CEDOC Chronic Diseases Research Center, NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Jorge Castanheira
- Laboratory Neuronal Trafficking in Aging, CEDOC Chronic Diseases Research Center, NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Cláudia Guimas Almeida
- Laboratory Neuronal Trafficking in Aging, CEDOC Chronic Diseases Research Center, NOVA Medical School, Universidade NOVA de Lisboa, Lisbon, Portugal
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18
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Kubis-Kubiak A, Dyba A, Piwowar A. The Interplay between Diabetes and Alzheimer's Disease-In the Hunt for Biomarkers. Int J Mol Sci 2020; 21:ijms21082744. [PMID: 32326589 PMCID: PMC7215807 DOI: 10.3390/ijms21082744] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/09/2020] [Accepted: 04/12/2020] [Indexed: 02/07/2023] Open
Abstract
The brain is an organ in which energy metabolism occurs most intensively and glucose is an essential and dominant energy substrate. There have been many studies in recent years suggesting a close relationship between type 2 diabetes mellitus (T2DM) and Alzheimer’s disease (AD) as they have many pathophysiological features in common. The condition of hyperglycemia exposes brain cells to the detrimental effects of glucose, increasing protein glycation and is the cause of different non-psychiatric complications. Numerous observational studies show that not only hyperglycemia but also blood glucose levels near lower fasting limits (72 to 99 mg/dL) increase the incidence of AD, regardless of whether T2DM will develop in the future. As the comorbidity of these diseases and earlier development of AD in T2DM sufferers exist, new AD biomarkers are being sought for etiopathogenetic changes associated with early neurodegenerative processes as a result of carbohydrate disorders. The S100B protein seem to be interesting in this respect as it may be a potential candidate, especially important in early diagnostics of these diseases, given that it plays a role in both carbohydrate metabolism disorders and neurodegenerative processes. It is therefore necessary to clarify the relationship between the concentration of the S100B protein and glucose and insulin levels. This paper draws attention to a valuable research objective that may in the future contribute to a better diagnosis of early neurodegenerative changes, in particular in subjects with T2DM and may be a good basis for planning experiments related to this issue as well as a more detailed explanation of the relationship between the neuropathological disturbances and changes of glucose and insulin concentrations in the brain.
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Affiliation(s)
- Adriana Kubis-Kubiak
- Department of Toxicology, Faculty of Pharmacy, Wroclaw Medical University, 50367 Wroclaw, Poland;
- Correspondence:
| | - Aleksandra Dyba
- Students Science Club of the Department of Toxicology, Faculty of Pharmacy, Wroclaw Medical University, 50367 Wroclaw, Poland;
| | - Agnieszka Piwowar
- Department of Toxicology, Faculty of Pharmacy, Wroclaw Medical University, 50367 Wroclaw, Poland;
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19
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Mehr A, Hick M, Ludewig S, Müller M, Herrmann U, von Engelhardt J, Wolfer DP, Korte M, Müller UC. Lack of APP and APLP2 in GABAergic Forebrain Neurons Impairs Synaptic Plasticity and Cognition. Cereb Cortex 2020; 30:4044-4063. [PMID: 32219307 DOI: 10.1093/cercor/bhaa025] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Amyloid-β precursor protein (APP) is central to the pathogenesis of Alzheimer's disease, yet its physiological functions remain incompletely understood. Previous studies had indicated important synaptic functions of APP and the closely related homologue APLP2 in excitatory forebrain neurons for spine density, synaptic plasticity, and behavior. Here, we show that APP is also widely expressed in several interneuron subtypes, both in hippocampus and cortex. To address the functional role of APP in inhibitory neurons, we generated mice with a conditional APP/APLP2 double knockout (cDKO) in GABAergic forebrain neurons using DlxCre mice. These DlxCre cDKO mice exhibit cognitive deficits in hippocampus-dependent spatial learning and memory tasks, as well as impairments in species-typic nesting and burrowing behaviors. Deficits at the behavioral level were associated with altered neuronal morphology and synaptic plasticity Long-Term Potentiation (LTP). Impaired basal synaptic transmission at the Schafer collateral/CA1 pathway, which was associated with altered compound excitatory/inhibitory synaptic currents and reduced action potential firing of CA1 pyramidal cells, points to a disrupted excitation/inhibition balance in DlxCre cDKOs. Together, these impairments may lead to hippocampal dysfunction. Collectively, our data reveal a crucial role of APP family proteins in inhibitory interneurons to maintain functional network activity.
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Affiliation(s)
- Annika Mehr
- Department of Functional Genomics, Institute of Pharmacy and Molecular Biotechnology (IPMB), University of Heidelberg, 69120 Heidelberg, Germany
| | - Meike Hick
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, 60590 Frankfurt am Main, Germany
| | - Susann Ludewig
- Division of Cellular Neurobiology, Zoological Institute, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Michaela Müller
- Institute of Pathophysiology, University Medical Center of the Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - Ulrike Herrmann
- Division of Cellular Neurobiology, Zoological Institute, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Jakob von Engelhardt
- Institute of Pathophysiology, University Medical Center of the Johannes Gutenberg University Mainz, 55128 Mainz, Germany
| | - David P Wolfer
- Institute of Anatomy, University of Zürich, 8057 Zürich, Switzerland.,Institute of Human Movement Sciences and Sport, ETH Zürich, 8057 Zürich, Switzerland
| | - Martin Korte
- Division of Cellular Neurobiology, Zoological Institute, Technische Universität Braunschweig, 38106 Braunschweig, Germany.,AG Neuroinflammation and Neurodegeneration, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Ulrike C Müller
- Department of Functional Genomics, Institute of Pharmacy and Molecular Biotechnology (IPMB), University of Heidelberg, 69120 Heidelberg, Germany.,Division of Cellular Neurobiology, Zoological Institute, Technische Universität Braunschweig, 38106 Braunschweig, Germany
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20
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Abstract
Regulated transport through the secretory pathway is essential for embryonic development and homeostasis. Disruptions in this process impact cell fate, differentiation and survival, often resulting in abnormalities in morphogenesis and in disease. Several congenital malformations are caused by mutations in genes coding for proteins that regulate cargo protein transport in the secretory pathway. The severity of mutant phenotypes and the unclear aetiology of transport protein-associated pathologies have motivated research on the regulation and mechanisms through which these proteins contribute to morphogenesis. This review focuses on the role of the p24/transmembrane emp24 domain (TMED) family of cargo receptors in development and disease.
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21
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Pronker MF, van den Hoek H, Janssen BJC. Design and structural characterisation of olfactomedin-1 variants as tools for functional studies. BMC Mol Cell Biol 2019; 20:50. [PMID: 31726976 PMCID: PMC6857237 DOI: 10.1186/s12860-019-0232-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 10/10/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Olfactomedin-1 (Olfm1; also known as Noelin or Pancortin) is a highly-expressed secreted brain and retina protein and its four isoforms have different roles in nervous system development and function. Structural studies showed that the long Olfm1 isoform BMZ forms a disulfide-linked tetramer with a V-shaped architecture. The tips of the Olfm1 "V" each consist of two C-terminal β-propeller domains that enclose a calcium binding site. Functional characterisation of Olfm1 may be aided by new biochemical tools derived from these core structural elements. RESULTS Here we present the production, purification and structural analysis of three novel monomeric, dimeric and tetrameric forms of mammalian Olfm1 for functional studies. We characterise these constructs structurally by high-resolution X-ray crystallography and small-angle X-ray scattering. The crystal structure of the Olfm1 β-propeller domain (to 1.25 Å) represents the highest-resolution structure of an olfactomedin family member to date, revealing features such as a hydrophilic tunnel containing water molecules running into the core of the domain where the calcium binding site resides. The shorter Olfactomedin-1 isoform BMY is a disulfide-linked tetramer with a shape similar to the corresponding region in the longer BMZ isoform. CONCLUSIONS These recombinantly-expressed protein tools should assist future studies, for example of biophysical, electrophysiological or morphological nature, to help elucidate the functions of Olfm1 in the mature mammalian brain. The control over the oligomeric state of Olfm1 provides a firm basis to better understand the role of Olfm1 in the (trans-synaptic) tethering or avidity-mediated clustering of synaptic receptors such as post-synaptic AMPA receptors and pre-synaptic amyloid precursor protein. In addition, the variation in domain composition of these protein tools provides a means to dissect the Olfm1 regions important for receptor binding.
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Affiliation(s)
- Matti F Pronker
- MRC Laboratory of Molecular Biology, Division of Neurobiology, Francis Crick Avenue, Cambridge, CB2 0QH, UK. .,Bijvoet Center for Biomolecular Research, Utrecht University, Crystal and Structural Chemistry, Kruytgebouw, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
| | - Hugo van den Hoek
- Bijvoet Center for Biomolecular Research, Utrecht University, Crystal and Structural Chemistry, Kruytgebouw, Padualaan 8, 3584 CH, Utrecht, The Netherlands.,Department of Molecular Structural Biology, Max Planck institute for Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Bert J C Janssen
- Bijvoet Center for Biomolecular Research, Utrecht University, Crystal and Structural Chemistry, Kruytgebouw, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
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22
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Tang BL. Amyloid Precursor Protein (APP) and GABAergic Neurotransmission. Cells 2019; 8:E550. [PMID: 31174368 PMCID: PMC6627941 DOI: 10.3390/cells8060550] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/25/2019] [Accepted: 06/06/2019] [Indexed: 12/16/2022] Open
Abstract
The amyloid precursor protein (APP) is the parent polypeptide from which amyloid-beta (Aβ) peptides, key etiological agents of Alzheimer's disease (AD), are generated by sequential proteolytic processing involving β- and γ-secretases. APP mutations underlie familial, early-onset AD, and the involvement of APP in AD pathology has been extensively studied. However, APP has important physiological roles in the mammalian brain, particularly its modulation of synaptic functions and neuronal survival. Recent works have now shown that APP could directly modulate γ-aminobutyric acid (GABA) neurotransmission in two broad ways. Firstly, APP is shown to interact with and modulate the levels and activity of the neuron-specific Potassium-Chloride (K+-Cl-) cotransporter KCC2/SLC12A5. The latter is key to the maintenance of neuronal chloride (Cl-) levels and the GABA reversal potential (EGABA), and is therefore important for postsynaptic GABAergic inhibition through the ionotropic GABAA receptors. Secondly, APP binds to the sushi domain of metabotropic GABAB receptor 1a (GABABR1a). In this regard, APP complexes and is co-transported with GABAB receptor dimers bearing GABABR1a to the axonal presynaptic plasma membrane. On the other hand, secreted (s)APP generated by secretase cleavages could act as a GABABR1a-binding ligand that modulates presynaptic vesicle release. The discovery of these novel roles and activities of APP in GABAergic neurotransmission underlies the physiological importance of APP in postnatal brain function.
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Affiliation(s)
- Bor Luen Tang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117597, Singapore.
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23
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Reciprocal modulation between amyloid precursor protein and synaptic membrane cholesterol revealed by live cell imaging. Neurobiol Dis 2019; 127:449-461. [PMID: 30885793 DOI: 10.1016/j.nbd.2019.03.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 02/03/2019] [Accepted: 03/12/2019] [Indexed: 12/20/2022] Open
Abstract
The amyloid precursor protein (APP) has been extensively studied because of its association with Alzheimer's disease (AD). However, APP distribution across different subcellular membrane compartments and its function in neurons remains unclear. We generated an APP fusion protein with a pH-sensitive green fluorescent protein at its ectodomain and a pH-insensitive blue fluorescent protein at its cytosolic domain and used it to measure APP's distribution, subcellular trafficking, and cleavage in live neurons. This reporter, closely resembling endogenous APP, revealed only a limited correlation between synaptic activities and APP trafficking. However, the synaptic surface fraction of APP was increased by a reduction in membrane cholesterol levels, a phenomenon that involves APP's cholesterol-binding motif. Mutations at or near binding sites not only reduced both the surface fraction of APP and membrane cholesterol levels in a dominant negative manner, but also increased synaptic vulnerability to moderate membrane cholesterol reduction. Our results reveal reciprocal modulation of APP and membrane cholesterol levels at synaptic boutons.
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24
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Presenilin-mediated cleavage of APP regulates synaptotagmin-7 and presynaptic plasticity. Nat Commun 2018; 9:4780. [PMID: 30429473 PMCID: PMC6235831 DOI: 10.1038/s41467-018-06813-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 09/19/2018] [Indexed: 11/09/2022] Open
Abstract
Mutations of the intramembrane protease presenilin (PS) or of its main substrate, the amyloid precursor protein (APP), cause early-onset form of Alzheimer disease. PS and APP interact with proteins of the neurotransmitter release machinery without identified functional consequences. Here we report that genetic deletion of PS markedly decreases the presynaptic levels of the Ca2+ sensor synaptotagmin-7 (Syt7) leading to impaired synaptic facilitation and replenishment of synaptic vesicles. The regulation of Syt7 expression by PS occurs post-transcriptionally and depends on γ-secretase proteolytic activity. It requires the substrate APP as revealed by the combined genetic invalidation of APP and PS1, and in particular the APP-Cterminal fragments which interact with Syt7 and accumulate in synaptic terminals under pharmacological or genetic inhibition of γ-secretase. Thus, we uncover a role of PS in presynaptic mechanisms, through APP cleavage and regulation of Syt7, that highlights aberrant synaptic vesicle processing as a possible new pathway in AD. Mutations in presenilin, which cleaves amyloid precursor protein, cause familial Alzheimer’s Disease. Here, the authors show that loss of presenilin leads to loss of synaptotagmin 7, leading to impaired presynaptic release.
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25
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Truong PH, Ciccotosto GD, Cappai R. Analysis of Motor Function in Amyloid Precursor-Like Protein 2 Knockout Mice: The Effects of Ageing and Sex. Neurochem Res 2018; 44:1356-1366. [PMID: 30362021 DOI: 10.1007/s11064-018-2669-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/18/2018] [Accepted: 10/20/2018] [Indexed: 12/19/2022]
Abstract
The amyloid precursor protein (APP) is a member of a conserved gene family that includes the amyloid precursor-like proteins 1 (APLP1) and 2 (APLP2). APP and APLP2 share a high degree of similarity, and have overlapping patterns of spatial and temporal expression in the central and peripheral tissues, in particular at the neuromuscular junction. APP-family knockout (KO) studies have helped elucidate aspects of function and functional redundancy amongst the APP-family members. In the present study, we investigated motor performance of APLP2-KO mice and the effect sex differences and age-related changes have on motor performance. APLP2-KO and WT (on C57Bl6 background) littermates control mice from 8 (young adulthood) to 48 weeks (middle age) were investigated. Analysis of motor neuron and muscle morphology showed APLP2-KO females but not males, had less age-related motor function impairments. We observed age and sex differences in both motor neuron number and muscle fiber size distribution for APLP2-KO mice compared to WT (C57Bl6). These alterations in the motor neuron number and muscle fiber distribution pattern may explain why female APLP2-KO mice have far better motor function behaviour during ageing.
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Affiliation(s)
- Phan H Truong
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Giuseppe D Ciccotosto
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Roberto Cappai
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia.
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26
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Beckert B, Acker-Palmer A, Volknandt W. Aβ42 oligomers impair the bioenergetic activity in hippocampal synaptosomes derived from APP-KO mice. Biol Chem 2018; 399:453-465. [PMID: 29337689 DOI: 10.1515/hsz-2017-0238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 12/20/2017] [Indexed: 11/15/2022]
Abstract
Employing hippocampal synaptosomes from amyloid precursor protein (APP)-deleted mice we analyzed the immediate effects of amyloid beta peptide 42 (Aβ42) peptide in its oligomeric or fibrillar assembly or of soluble amyloid precursor protein alpha (sAPPα) protein on their bioenergetic activity. Upon administration of oligomeric Aβ42 peptide for 30 min we observed a robust decrease both in mitochondrial activity and in mitochondrial membrane potential (MMP). In contrast the respective fibrillary or scrambled peptides showed no effect, indicating that inhibition strictly depends on the oligomerization status of the peptide. Hippocampal synaptosomes from old APP-KO mice revealed a further reduction of their already impaired bioenergetic activity upon incubation with 10 μm Aβ42 peptide. In addition we evaluated the influence of the sAPPα protein on mitochondrial activity of hippocampal synaptosomes derived from young or old APP-KO animals. In neither case 20 nm nor 200 nm sAPPα protein had an effect on mitochondrial metabolic activity. Our findings demonstrate that hippocampal synaptosomes derived from APP-KO mice are a most suitable model system to evaluate the impact of Aβ42 peptide on its bioenergetic activity and to further elucidate the molecular mechanisms underlying the impairments by oligomeric Aβ42 on mitochondrial function. Our data demonstrate that extracellular Aβ42 peptide is taken up into synaptosomes where it immediately attenuates mitochondrial activity.
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Affiliation(s)
- Benedikt Beckert
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, D-60438, Frankfurt/Main, Germany
| | - Amparo Acker-Palmer
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, D-60438, Frankfurt/Main, Germany
- Max Planck Institute for Brain Research, Max-von-Laue-Str. 4, D-60438 Frankfurt/Main, Germany
| | - Walter Volknandt
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, D-60438, Frankfurt/Main, Germany
- Department for Molecular and Cellular Neurobiology, Goethe University Frankfurt, Max-von-Laue-Str. 13, D-60438 Frankfurt, Germany
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27
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Longhena F, Spano P, Bellucci A. Targeting of Disordered Proteins by Small Molecules in Neurodegenerative Diseases. Handb Exp Pharmacol 2018; 245:85-110. [PMID: 28965171 DOI: 10.1007/164_2017_60] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The formation of protein aggregates and inclusions in the brain and spinal cord is a common neuropathological feature of a number of neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and many others. These are commonly referred as neurodegenerative proteinopathies or protein-misfolding diseases. The main characteristic of protein aggregates in these disorders is the fact that they are enriched in amyloid fibrils. Since protein aggregation is considered to play a central role for the onset of neurodegenerative proteinopathies, research is ongoing to develop strategies aimed at preventing or removing protein aggregation in the brain of affected patients. Numerous studies have shown that small molecule-based approaches may be potentially the most promising for halting protein aggregation in neurodegenerative diseases. Indeed, several of these compounds have been found to interact with intrinsically disordered proteins and promote their clearing in experimental models. This notwithstanding, at present small molecule inhibitors still awaits achievements for clinical translation. Hopefully, if we determine whether the formation of insoluble inclusions is effectively neurotoxic and find a valid biomarker to assess their protein aggregation-inhibitory activity in the human central nervous system, the use of small molecule inhibitors will be considered as a cure for neurodegenerative protein-misfolding diseases.
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Affiliation(s)
- Francesca Longhena
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa No. 11, Brescia, 25123, Italy
| | - PierFranco Spano
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa No. 11, Brescia, 25123, Italy
| | - Arianna Bellucci
- Division of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa No. 11, Brescia, 25123, Italy.
- Laboratory of Personalized and Preventive Medicine, University of Brescia, Brescia, Italy.
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28
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Human Brain-Derived Aβ Oligomers Bind to Synapses and Disrupt Synaptic Activity in a Manner That Requires APP. J Neurosci 2017; 37:11947-11966. [PMID: 29101243 DOI: 10.1523/jneurosci.2009-17.2017] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 09/19/2017] [Accepted: 09/29/2017] [Indexed: 12/20/2022] Open
Abstract
Compelling genetic evidence links the amyloid precursor protein (APP) to Alzheimer's disease (AD) and several theories have been advanced to explain the relationship. A leading hypothesis proposes that a small amphipathic fragment of APP, the amyloid β-protein (Aβ), self-associates to form soluble aggregates that impair synaptic and network activity. Here, we used the most disease-relevant form of Aβ, protein isolated from AD brain. Using this material, we show that the synaptotoxic effects of Aβ depend on expression of APP and that the Aβ-mediated impairment of synaptic plasticity is accompanied by presynaptic effects that disrupt the excitatory/inhibitory (E/I) balance. The net increase in the E/I ratio and inhibition of plasticity are associated with Aβ localizing to synapses and binding of soluble Aβ aggregates to synapses requires the expression of APP. Our findings indicate a role for APP in AD pathogenesis beyond the generation of Aβ and suggest modulation of APP expression as a therapy for AD.SIGNIFICANCE STATEMENT Here, we report on the plasticity-disrupting effects of amyloid β-protein (Aβ) isolated from Alzheimer's disease (AD) brain and the requirement of amyloid precursor protein (APP) for these effects. We show that Aβ-containing AD brain extracts block hippocampal LTP, augment glutamate release probability, and disrupt the excitatory/inhibitory balance. These effects are associated with Aβ localizing to synapses and genetic ablation of APP prevents both Aβ binding and Aβ-mediated synaptic dysfunctions. Our results emphasize the importance of APP in AD and should stimulate new studies to elucidate APP-related targets suitable for pharmacological manipulation.
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29
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Pliássova A, Canas PM, Xavier AC, da Silva BS, Cunha RA, Agostinho P. Age-Related Changes in the Synaptic Density of Amyloid-β Protein Precursor and Secretases in the Human Cerebral Cortex. J Alzheimers Dis 2017; 52:1209-14. [PMID: 27104908 DOI: 10.3233/jad-160213] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Amyloid-β protein precursor (AβPP) is involved in synaptic formation and function. In the human cingulate cortex, AβPP was preferentially located in the presynaptic active zone as in rodents, indicating a preserved subsynaptic AβPP distribution across species and brain regions. Synaptic AβPP immunoreactivity was decreased with aging in cortical samples collected from autopsies of males (20-80 years), whereas the synaptic levels of α-secretase (ADAM10) and β-secretase (BACE1) did not significantly change. Decreased AβPP levels may be related to lower allostasis of synapses in the aged brain and their greater susceptibility to dysfunction characteristic of the onset of neurodegenerative disorders.
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Affiliation(s)
- Anna Pliássova
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.,FMUC - Faculty of Medicine, University of Coimbra, Portugal
| | - Paula M Canas
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.,FMUC - Faculty of Medicine, University of Coimbra, Portugal
| | - Ana Carolina Xavier
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Portugal
| | - Beatriz S da Silva
- Portuguese National Institute of Legal Medicine and Forensic Sciences (INMLCF IP), Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.,FMUC - Faculty of Medicine, University of Coimbra, Portugal
| | - Paula Agostinho
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.,FMUC - Faculty of Medicine, University of Coimbra, Portugal
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30
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Liu A, Zhang Y, Han L, He G, Xie W, Zhou Z, Jia Z. Regulation of Neurotransmitter Release by Amyloid Precursor Protein Through Synapsin Phosphorylation. Neurochem Res 2017; 44:683-691. [PMID: 29052089 DOI: 10.1007/s11064-017-2418-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 10/01/2017] [Accepted: 10/09/2017] [Indexed: 12/19/2022]
Abstract
Abnormal processing of amyloid precursor protein (APP) and aggregation of the Aβ peptide are known to play a key role in the pathogenesis of Alzheimer disease, but the function of endogenous APP under normal physiological conditions remains poorly understood. In this study, we investigated presynaptic changes in APP knockout (KO) mice. We demonstrate that both sucrose-induced neurotransmission and synaptic depletion in response to high frequency stimulation are significantly enhanced in APP KO compared to wild type littermates. In addition, the level of phosphorylated forms of synapsins, but not total synapsins, is elevated in the KO mice. Furthermore, we show that the inhibition of L-type calcium channels normalizes phosphorylated synapsins and slows down the high frequency induced synaptic depletion in APP KO mice. These results suggest a new mechanism by which APP regulates synaptic vesicle dynamics through synapsin-dependent phosphorylation.
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Affiliation(s)
- An Liu
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Ying Zhang
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Lifang Han
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Guiqin He
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Wei Xie
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Zikai Zhou
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Zhengping Jia
- Neurosciences & Mental Health, the Hospital for Sick Children, 555 University Ave., Toronto, ON, M5G 1X8, Canada. .,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
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31
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Saburova EA, Vasiliev AN, Kravtsova VV, Ryabova EV, Zefirov AL, Bolshakova OI, Sarantseva SV, Krivoi II. Human APP Gene Expression Alters Active Zone Distribution and Spontaneous Neurotransmitter Release at the Drosophila Larval Neuromuscular Junction. Neural Plast 2017; 2017:9202584. [PMID: 28770114 PMCID: PMC5523229 DOI: 10.1155/2017/9202584] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/07/2017] [Indexed: 12/11/2022] Open
Abstract
This study provides further insight into the molecular mechanisms that control neurotransmitter release. Experiments were performed on larval neuromuscular junctions of transgenic Drosophila melanogaster lines with different levels of human amyloid precursor protein (APP) production. To express human genes in motor neurons of Drosophila, the UAS-GAL4 system was used. Human APP gene expression increased the number of synaptic boutons per neuromuscular junction. The total number of active zones, detected by Bruchpilot protein puncta distribution, remained unchanged; however, the average number of active zones per bouton decreased. These disturbances were accompanied by a decrease in frequency of miniature excitatory junction potentials without alteration in random nature of spontaneous quantal release. Similar structural and functional changes were observed with co-overexpression of human APP and β-secretase genes. In Drosophila line with expression of human amyloid-β42 peptide itself, parameters analyzed did not differ from controls, suggesting the specificity of APP effects. These results confirm the involvement of APP in synaptogenesis and provide evidence to suggest that human APP overexpression specifically disturbs the structural and functional organization of active zone and results in altered Bruchpilot distribution and lowered probability of spontaneous neurotransmitter release.
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Affiliation(s)
- Ekaterina A. Saburova
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Alexander N. Vasiliev
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Violetta V. Kravtsova
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Elena V. Ryabova
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Centre “Kurchatov Institute”, Gatchina 188300, Russia
| | - Andrey L. Zefirov
- Department of Normal Physiology, Kazan State Medical University, Kazan 420012, Russia
| | - Olga I. Bolshakova
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Centre “Kurchatov Institute”, Gatchina 188300, Russia
| | - Svetlana V. Sarantseva
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Centre “Kurchatov Institute”, Gatchina 188300, Russia
| | - Igor I. Krivoi
- Department of General Physiology, St. Petersburg State University, St. Petersburg 199034, Russia
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32
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Han K, Müller UC, Hülsmann S. Amyloid-precursor Like Proteins APLP1 and APLP2 Are Dispensable for Normal Development of the Neonatal Respiratory Network. Front Mol Neurosci 2017; 10:189. [PMID: 28690498 PMCID: PMC5479907 DOI: 10.3389/fnmol.2017.00189] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 05/29/2017] [Indexed: 11/13/2022] Open
Abstract
Recent studies using animal models indicated that the members of the amyloid precursor protein (APP) gene family are important for the formation, maintenance, and plasticity of synapses. Despite this, the specific role of the APP homologs APLP1 and APLP2 within the CNS and PNS is still poorly understood. In contrast to the subtle phenotypes of single mutants, double knockout mice (DKO) lacking APP/APLP2 or APLP1/APLP2 die within the first day after birth. Whereas APP/APLP2-DKO mice show severe deficits of neuromuscular morphology and transmission, the underlying cause of lethality of APLP1/APLP2-DKO mice remains unclear. Since expression of both proteins was confirmed by in situ hybridization, we aimed to test the role of APLP1/APLP2 in the formation and maintenance of synapses in the brainstem, and assessed a potential dysfunction of the most vital central neuronal network in APLP1/APLP2-DKO mice by analyzing the respiratory network of the medulla. We performed in vivo unrestrained whole body plethysmography in newborn APLP1/APLP2-DKO mice at postnatal day zero. Additionally, we directly tested the activity of the respiratory network in an acute slice preparation that includes the pre-Bötzinger complex. In both sets of experiments, no significant differences were detected regarding respiratory rate and cycle variability, strongly arguing against central respiratory problems as the primary cause of death of APLP1/APLP2-DKO mice. Thus, we conclude that APLP1 and APLP2 are dispensable for the development of the network and the generation of a normal breathing rhythm.
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Affiliation(s)
- Kang Han
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg UniversityHeidelberg, Germany
| | - Ulrike C Müller
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg UniversityHeidelberg, Germany
| | - Swen Hülsmann
- Klinik für Anästhesiologie, Universitätsmedizin GöttingenGöttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB)Göttingen, Germany
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33
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APLP1 Is a Synaptic Cell Adhesion Molecule, Supporting Maintenance of Dendritic Spines and Basal Synaptic Transmission. J Neurosci 2017; 37:5345-5365. [PMID: 28450540 DOI: 10.1523/jneurosci.1875-16.2017] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 02/22/2017] [Accepted: 03/24/2017] [Indexed: 12/19/2022] Open
Abstract
The amyloid precursor protein (APP), a key player in Alzheimer's disease, belongs to the family of synaptic adhesion molecules (SAMs) due to its impact on synapse formation and synaptic plasticity. These functions are mediated by both the secreted APP ectodomain that acts as a neurotrophic factor and full-length APP forming trans-cellular dimers. Two homologs of APP exist in mammals: the APP like proteins APLP1 and APLP2, exhibiting functions that partly overlap with those of APP. Here we tested whether APLP1 and APLP2 also show features of SAMs. We found that all three family members were upregulated during postnatal development coinciding with synaptogenesis. We observed presynaptic and postsynaptic localization of all APP family members and could show that heterologous expression of APLP1 or APLP2 in non-neuronal cells induces presynaptic differentiation in contacting axons of cocultured neurons, similar to APP and other SAMs. Moreover, APP/APLPs all bind to synaptic-signaling molecules, such as MINT/X11. Furthermore, we report that aged APLP1 knock-out mice show impaired basal transmission and a reduced mEPSC frequency, likely resulting from reduced spine density. This demonstrates an essential nonredundant function of APLP1 at the synapse. Compared to APP, APLP1 exhibits increased trans-cellular binding and elevated cell-surface levels due to reduced endocytosis. In conclusion, our results establish that APLPs show typical features of SAMs and indicate that increased surface expression, as observed for APLP1, is essential for proper synapse formation in vitro and synapse maintenance in vivoSIGNIFICANCE STATEMENT According to the amyloid-cascade hypothesis, Alzheimer's disease is caused by the accumulation of Aβ peptides derived from sequential cleavage of the amyloid precursor protein (APP) by β-site APP cleaving enzyme 1 (BACE1) and γ-secretase. Here we show that all mammalian APP family members (APP, APLP1, and APLP2) exhibit synaptogenic activity, involving trans-synaptic dimerization, similar to other synaptic cell adhesion molecules, such as Neuroligin/Neurexin. Importantly, our study revealed that the loss of APLP1, which is one of the major substrates of BACE1, causes reduced spine density in aged mice. Because some therapeutic interventions target APP processing (e.g., BACE inhibitors), those strategies may alter APP/APLP physiological function. This should be taken into account for the development of pharmaceutical treatments of Alzheimer's disease.
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Not just amyloid: physiological functions of the amyloid precursor protein family. Nat Rev Neurosci 2017; 18:281-298. [PMID: 28360418 DOI: 10.1038/nrn.2017.29] [Citation(s) in RCA: 382] [Impact Index Per Article: 54.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Amyloid precursor protein (APP) gives rise to the amyloid-β peptide and thus has a key role in the pathogenesis of Alzheimer disease. By contrast, the physiological functions of APP and the closely related APP-like proteins (APLPs) remain less well understood. Studying these physiological functions has been challenging and has required a careful long-term strategy, including the analysis of different App-knockout and Aplp-knockout mice. In this Review, we summarize these findings, focusing on the in vivo roles of APP family members and their processing products for CNS development, synapse formation and function, brain injury and neuroprotection, as well as ageing. In addition, we discuss the implications of APP physiology for therapeutic approaches.
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Weingarten J, Weingarten M, Wegner M, Volknandt W. APP-A Novel Player within the Presynaptic Active Zone Proteome. Front Mol Neurosci 2017; 10:43. [PMID: 28265241 PMCID: PMC5316543 DOI: 10.3389/fnmol.2017.00043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/07/2017] [Indexed: 11/13/2022] Open
Abstract
The amyloid precursor protein (APP) was discovered in the 1980s as the precursor protein of the amyloid A4 peptide. The amyloid A4 peptide, also known as A-beta (Aβ), is the main constituent of senile plaques implicated in Alzheimer's disease (AD). In association with the amyloid deposits, increasing impairments in learning and memory as well as the degeneration of neurons especially in the hippocampus formation are hallmarks of the pathogenesis of AD. Within the last decades much effort has been expended into understanding the pathogenesis of AD. However, little is known about the physiological role of APP within the central nervous system (CNS). Allocating APP to the proteome of the highly dynamic presynaptic active zone (PAZ) identified APP as a novel player within this neuronal communication and signaling network. The analysis of the hippocampal PAZ proteome derived from APP-mutant mice demonstrates that APP is tightly embedded in the underlying protein network. Strikingly, APP deletion accounts for major dysregulation within the PAZ proteome network. Ca2+-homeostasis, neurotransmitter release and mitochondrial function are affected and resemble the outcome during the pathogenesis of AD. The observed changes in protein abundance that occur in the absence of APP as well as in AD suggest that APP is a structural and functional regulator within the hippocampal PAZ proteome. Within this review article, we intend to introduce APP as an important player within the hippocampal PAZ proteome and to outline the impact of APP deletion on individual PAZ proteome subcommunities.
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Affiliation(s)
- Jens Weingarten
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Goethe University Frankfurt am Main, Germany
| | - Melanie Weingarten
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Goethe University Frankfurt am Main, Germany
| | - Martin Wegner
- Department of Molecular Bioinformatics, Goethe University Frankfurt am Main, Germany
| | - Walter Volknandt
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Goethe University Frankfurt am Main, Germany
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Roberts HL, Schneider BL, Brown DR. α-Synuclein increases β-amyloid secretion by promoting β-/γ-secretase processing of APP. PLoS One 2017; 12:e0171925. [PMID: 28187176 PMCID: PMC5302447 DOI: 10.1371/journal.pone.0171925] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 01/29/2017] [Indexed: 11/18/2022] Open
Abstract
α-Synuclein misfolding and aggregation is often accompanied by β-amyloid deposition in some neurodegenerative diseases. We hypothesised that α-synuclein promotes β-amyloid production from APP. β-Amyloid levels and APP amyloidogenic processing were investigated in neuronal cell lines stably overexpressing wildtype and mutant α-synuclein. γ-Secretase activity and β-secretase expression were also measured. We show that α-synuclein expression induces β-amyloid secretion and amyloidogenic processing of APP in neuronal cell lines. Certain mutations of α-synuclein potentiate APP amyloidogenic processing. γ-Secretase activity was not enhanced by wildtype α-synuclein expression, however β-secretase protein levels were induced. Furthermore, a correlation between α-synuclein and β-secretase protein was seen in rat brain striata. Iron chelation abolishes the effect of α-synuclein on neuronal cell β-amyloid secretion, whereas overexpression of the ferrireductase enzyme Steap3 is robustly pro-amyloidogenic. We propose that α-synuclein promotes β-amyloid formation by modulating β-cleavage of APP, and that this is potentially mediated by the levels of reduced iron and oxidative stress.
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Affiliation(s)
- Hazel L. Roberts
- Department of Biology & Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
| | - Bernard L. Schneider
- Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - David R. Brown
- Department of Biology & Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom
- * E-mail:
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Ludewig S, Korte M. Novel Insights into the Physiological Function of the APP (Gene) Family and Its Proteolytic Fragments in Synaptic Plasticity. Front Mol Neurosci 2017; 9:161. [PMID: 28163673 PMCID: PMC5247455 DOI: 10.3389/fnmol.2016.00161] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 12/14/2016] [Indexed: 12/31/2022] Open
Abstract
The amyloid precursor protein (APP) is well known to be involved in the pathophysiology of Alzheimer's disease (AD) via its cleavage product amyloid ß (Aß). However, the physiological role of APP, its various proteolytic products and the amyloid precursor-like proteins 1 and 2 (APLP1/2) are still not fully clarified. Interestingly, it has been shown that learning and memory processes represented by functional and structural changes at synapses are altered in different APP and APLP1/2 mouse mutants. In addition, APP and its fragments are implicated in regulating synaptic strength further reinforcing their modulatory role at the synapse. While APLP2 and APP are functionally redundant, the exclusively CNS expressed APLP1, might have individual roles within the synaptic network. The proteolytic product of non-amyloidogenic APP processing, APPsα, emerged as a neurotrophic peptide that facilitates long-term potentiation (LTP) and restores impairments occurring with age. Interestingly, the newly discovered η-secretase cleavage product, An-α acts in the opposite direction, namely decreasing LTP. In this review we summarize recent findings with emphasis on the physiological role of the APP gene family and its proteolytic products on synaptic function and plasticity, especially during processes of hippocampal LTP. Therefore, we focus on literature that provide electrophysiological data by using different mutant mouse strains either lacking full-length or parts of the APP proteins or that utilized secretase inhibitors as well as secreted APP fragments.
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Affiliation(s)
- Susann Ludewig
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig Braunschweig, Germany
| | - Martin Korte
- Division of Cellular Neurobiology, Zoological Institute, TU BraunschweigBraunschweig, Germany; Helmholtz Centre for Infection Research, AG NINDBraunschweig, Germany
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Laßek M, Weingarten J, Wegner M, Neupärtl M, Array TN, Harde E, Beckert B, Golghalyani V, Ackermann J, Koch I, Müller UC, Karas M, Acker-Palmer A, Volknandt W. APP Deletion Accounts for Age-Dependent Changes in the Bioenergetic Metabolism and in Hyperphosphorylated CaMKII at Stimulated Hippocampal Presynaptic Active Zones. Front Synaptic Neurosci 2017; 9:1. [PMID: 28163681 PMCID: PMC5247443 DOI: 10.3389/fnsyn.2017.00001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/05/2017] [Indexed: 11/13/2022] Open
Abstract
Synaptic release sites are characterized by exocytosis-competent synaptic vesicles tightly anchored to the presynaptic active zone (PAZ) whose proteome orchestrates the fast signaling events involved in synaptic vesicle cycle and plasticity. Allocation of the amyloid precursor protein (APP) to the PAZ proteome implicated a functional impact of APP in neuronal communication. In this study, we combined state-of-the-art proteomics, electrophysiology and bioinformatics to address protein abundance and functional changes at the native hippocampal PAZ in young and old APP-KO mice. We evaluated if APP deletion has an impact on the metabolic activity of presynaptic mitochondria. Furthermore, we quantified differences in the phosphorylation status after long-term-potentiation (LTP) induction at the purified native PAZ. We observed an increase in the phosphorylation of the signaling enzyme calmodulin-dependent kinase II (CaMKII) only in old APP-KO mice. During aging APP deletion is accompanied by a severe decrease in metabolic activity and hyperphosphorylation of CaMKII. This attributes an essential functional role to APP at hippocampal PAZ and putative molecular mechanisms underlying the age-dependent impairments in learning and memory in APP-KO mice.
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Affiliation(s)
- Melanie Laßek
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Jens Weingarten
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Martin Wegner
- Molecular Bioinformatics, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Moritz Neupärtl
- Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | | | - Eva Harde
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-UniversitätFrankfurt, Germany; Max Planck Institute for Brain ResearchFrankfurt, Germany
| | - Benedikt Beckert
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Vahid Golghalyani
- Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Jörg Ackermann
- Molecular Bioinformatics, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Ina Koch
- Molecular Bioinformatics, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Ulrike C Müller
- Department of Pharmacy and Molecular Biotechnology, University Heidelberg Heidelberg, Germany
| | - Michael Karas
- Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Amparo Acker-Palmer
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-UniversitätFrankfurt, Germany; Max Planck Institute for Brain ResearchFrankfurt, Germany
| | - Walter Volknandt
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-Universität Frankfurt, Germany
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Del Turco D, Paul MH, Schlaudraff J, Hick M, Endres K, Müller UC, Deller T. Region-Specific Differences in Amyloid Precursor Protein Expression in the Mouse Hippocampus. Front Mol Neurosci 2016; 9:134. [PMID: 27965537 PMCID: PMC5126089 DOI: 10.3389/fnmol.2016.00134] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/15/2016] [Indexed: 12/20/2022] Open
Abstract
The physiological role of amyloid precursor protein (APP) has been extensively investigated in the rodent hippocampus. Evidence suggests that APP plays a role in synaptic plasticity, dendritic and spine morphogenesis, neuroprotection and—at the behavioral level—hippocampus-dependent forms of learning and memory. Intriguingly, however, studies focusing on the role of APP in synaptic plasticity have reported diverging results and considerable differences in effect size between the dentate gyrus (DG) and area CA1 of the mouse hippocampus. We speculated that regional differences in APP expression could underlie these discrepancies and studied the expression of APP in both regions using immunostaining, in situ hybridization (ISH), and laser microdissection (LMD) in combination with quantitative reverse transcription polymerase chain reaction (RT-qPCR) and western blotting. In sum, our results show that APP is approximately 1.7-fold higher expressed in pyramidal cells of Ammon’s horn than in granule cells of the DG. This regional difference in APP expression may explain why loss-of-function approaches using APP-deficient mice revealed a role for APP in Hebbian plasticity in area CA1, whereas this could not be shown in the DG of the same APP mutants.
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Affiliation(s)
- Domenico Del Turco
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Germany
| | - Mandy H Paul
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Germany
| | - Jessica Schlaudraff
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Germany
| | - Meike Hick
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-UniversityFrankfurt, Germany; Institute of Pharmacy and Molecular Biotechnology (IPMB), Heidelberg UniversityHeidelberg, Germany
| | - Kristina Endres
- Clinic for Psychiatry and Psychotherapy, University Medical Center Mainz Mainz, Germany
| | - Ulrike C Müller
- Institute of Pharmacy and Molecular Biotechnology (IPMB), Heidelberg University Heidelberg, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Germany
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Bernardo TC, Marques-Aleixo I, Beleza J, Oliveira PJ, Ascensão A, Magalhães J. Physical Exercise and Brain Mitochondrial Fitness: The Possible Role Against Alzheimer's Disease. Brain Pathol 2016; 26:648-63. [PMID: 27328058 PMCID: PMC8029062 DOI: 10.1111/bpa.12403] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 06/15/2016] [Indexed: 12/21/2022] Open
Abstract
Exercise is one of the most effective strategies to maintain a healthy body and mind, with particular beneficial effects of exercise on promoting brain plasticity, increasing cognition and reducing the risk of cognitive decline and dementia in later life. Moreover, the beneficial effects resulting from increased physical activity occur at different levels of cellular organization, mitochondria being preferential target organelles. The relevance of this review article relies on the need to integrate the current knowledge of proposed mechanisms, focus mitochondria, to explain the protective effects of exercise that might underlie neuroplasticity and seeks to synthesize these data in the context of exploring exercise as a feasible intervention to delay cognitive impairment associated with neurodegenerative conditions, particularly Alzheimer disease.
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Affiliation(s)
- T C Bernardo
- CIAFEL-Research Centre in Physical Activity, , Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal.
| | - I Marques-Aleixo
- CIAFEL-Research Centre in Physical Activity, , Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal
| | - J Beleza
- CIAFEL-Research Centre in Physical Activity, , Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal
| | - P J Oliveira
- CNC-Centre for Neuroscience and Cell Biology, UC-Biotech, Biocant Park, University of Coimbra, Coimbra, Portugal
| | - A Ascensão
- CIAFEL-Research Centre in Physical Activity, , Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal
| | - J Magalhães
- CIAFEL-Research Centre in Physical Activity, , Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal
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41
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Liu L, Watanabe N, Akatsu H, Nishimura M. Neuronal expression of ILEI/FAM3C and its reduction in Alzheimer's disease. Neuroscience 2016; 330:236-46. [PMID: 27256505 DOI: 10.1016/j.neuroscience.2016.05.050] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/20/2016] [Accepted: 05/25/2016] [Indexed: 01/22/2023]
Abstract
Decrease in brain amyloid-β (Aβ) accumulation is a leading strategy for treating Alzheimer's disease (AD). However, the intrinsic mechanism of the regulation of brain Aβ production is largely unknown. Previously, we reported that ILEI (also referred to as FAM3C) binds to the γ-secretase complex and suppresses Aβ production without inhibiting γ-secretase activity. In this study, we examined ILEI expression in mouse brain using immunohistochemistry and subcellular fractionation. Brain ILEI showed widespread expression in neurons and ependymal cells but not in glial and vascular endothelial cells. Neuronal ILEI resided in perinuclear vesicular structures, which were positive for a marker protein of the trans-Golgi network. Although ILEI immunostaining was negative at synaptic terminals, synaptosome fractionation analysis suggested that ILEI was enriched in presynaptic terminals, particularly in the active zone-docked synaptic vesicles. ILEI expression levels in brain peaked during the postnatal period and declined with age. In comparison with age-matched control brains, the number of ILEI-immunoreactive neurons decreased in AD brains, although the subcellular localization was unaltered. Our results suggest that a decline of ILEI expression may cause accumulation of Aβ in the brain and the eventual development of AD.
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Affiliation(s)
- Lei Liu
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
| | - Naoki Watanabe
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
| | - Hiroyasu Akatsu
- Choju Medical Institute, Fukushimura Hospital, Toyohashi, Aichi 441-8124, Japan
| | - Masaki Nishimura
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
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42
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The APP Intracellular Domain Is Required for Normal Synaptic Morphology, Synaptic Plasticity, and Hippocampus-Dependent Behavior. J Neurosci 2016; 35:16018-33. [PMID: 26658856 DOI: 10.1523/jneurosci.2009-15.2015] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED The amyloid precursor protein family (APP/APLPs) has essential roles for neuromuscular synapse development and for the formation and plasticity of synapses within the CNS. Despite this, it has remained unclear whether APP mediates its functions primarily as a cell surface adhesion and signaling molecule or via its numerous proteolytic cleavage products. To address these questions, we followed a genetic approach and used APPΔCT15 knockin mice lacking the last 15 amino acids of APP, including the highly conserved YENPTY protein interaction motif. To circumvent functional compensation by the closely related APLP2, these mice were bred to an APLP2-KO background to generate APPΔCT15-DM double mutants. These APPΔCT15-DM mice were partially viable and displayed defects in neuromuscular synapse morphology and function with impairments in the ability to sustain transmitter release that resulted in muscular weakness. In the CNS, we demonstrate pronounced synaptic deficits including impairments in LTP that were associated with deficits in spatial learning and memory. Thus, the APP-CT15 domain provides essential physiological functions, likely via recruitment of specific interactors. Together with the well-established role of APPsα for synaptic plasticity, this shows that multiple domains of APP, including the conserved C-terminus, mediate signals required for normal PNS and CNS physiology. In addition, we demonstrate that lack of the APP-CT15 domain strongly impairs Aβ generation in vivo, establishing the APP C-terminus as a target for Aβ-lowering strategies. SIGNIFICANCE STATEMENT Synaptic dysfunction and cognitive decline are early hallmark features of Alzheimer's disease. Thus, it is essential to elucidate the in vivo function(s) of APP at the synapse. At present, it is unknown whether APP family proteins function as cell surface receptors, or mainly via shedding of their secreted ectodomains, such as neurotrophic APPsα. Here, to dissect APP functional domains, we used APP mutant mice lacking the last 15 amino acids that were crossed onto an APLP2-KO background. These APPΔCT15-DM mice showed defects in neuromuscular morphology and function. Synaptic deficits in the CNS included impairments of synaptic plasticity, spatial learning, and memory. Collectively, this indicates that multiple APP domains, including the C-terminus, are required for normal nervous system function.
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Laßek M, Weingarten J, Wegner M, Mueller BF, Rohmer M, Baeumlisberger D, Arrey TN, Hick M, Ackermann J, Acker-Palmer A, Koch I, Müller U, Karas M, Volknandt W. APP Is a Context-Sensitive Regulator of the Hippocampal Presynaptic Active Zone. PLoS Comput Biol 2016; 12:e1004832. [PMID: 27092780 PMCID: PMC4836664 DOI: 10.1371/journal.pcbi.1004832] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 02/25/2016] [Indexed: 01/18/2023] Open
Abstract
The hallmarks of Alzheimer's disease (AD) are characterized by cognitive decline and behavioral changes. The most prominent brain region affected by the progression of AD is the hippocampal formation. The pathogenesis involves a successive loss of hippocampal neurons accompanied by a decline in learning and memory consolidation mainly attributed to an accumulation of senile plaques. The amyloid precursor protein (APP) has been identified as precursor of Aβ-peptides, the main constituents of senile plaques. Until now, little is known about the physiological function of APP within the central nervous system. The allocation of APP to the proteome of the highly dynamic presynaptic active zone (PAZ) highlights APP as a yet unknown player in neuronal communication and signaling. In this study, we analyze the impact of APP deletion on the hippocampal PAZ proteome. The native hippocampal PAZ derived from APP mouse mutants (APP-KOs and NexCreAPP/APLP2-cDKOs) was isolated by subcellular fractionation and immunopurification. Subsequently, an isobaric labeling was performed using TMT6 for protein identification and quantification by high-resolution mass spectrometry. We combine bioinformatics tools and biochemical approaches to address the proteomics dataset and to understand the role of individual proteins. The impact of APP deletion on the hippocampal PAZ proteome was visualized by creating protein-protein interaction (PPI) networks that incorporated APP into the synaptic vesicle cycle, cytoskeletal organization, and calcium-homeostasis. The combination of subcellular fractionation, immunopurification, proteomic analysis, and bioinformatics allowed us to identify APP as structural and functional regulator in a context-sensitive manner within the hippocampal active zone network.
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Affiliation(s)
- Melanie Laßek
- Institute for Cell Biology and Neuroscience, Biologicum, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
| | - Jens Weingarten
- Institute for Cell Biology and Neuroscience, Biologicum, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
| | - Martin Wegner
- Institute for Molecular Bioinformatics, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
| | - Benjamin F. Mueller
- Institute of Pharmaceutical Chemistry, Cluster of Excellence “Macromolecular Complexes”, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
| | - Marion Rohmer
- Institute of Pharmaceutical Chemistry, Cluster of Excellence “Macromolecular Complexes”, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
| | | | | | - Meike Hick
- Department of Pharmacy and Molecular Biotechnology, University Heidelberg, Heidelberg Germany
| | - Jörg Ackermann
- Institute for Molecular Bioinformatics, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
| | - Amparo Acker-Palmer
- Institute for Cell Biology and Neuroscience, Biologicum, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
| | - Ina Koch
- Institute for Molecular Bioinformatics, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
| | - Ulrike Müller
- Department of Pharmacy and Molecular Biotechnology, University Heidelberg, Heidelberg Germany
| | - Michael Karas
- Institute of Pharmaceutical Chemistry, Cluster of Excellence “Macromolecular Complexes”, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
| | - Walter Volknandt
- Institute for Cell Biology and Neuroscience, Biologicum, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
- * E-mail:
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44
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Plummer S, Van den Heuvel C, Thornton E, Corrigan F, Cappai R. The Neuroprotective Properties of the Amyloid Precursor Protein Following Traumatic Brain Injury. Aging Dis 2016; 7:163-79. [PMID: 27114849 PMCID: PMC4809608 DOI: 10.14336/ad.2015.0907] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 09/07/2015] [Indexed: 01/16/2023] Open
Abstract
Despite the significant health and economic burden that traumatic brain injury (TBI) places on society, the development of successful therapeutic agents have to date not translated into efficacious therapies in human clinical trials. Injury to the brain is ongoing after TBI, through a complex cascade of primary and secondary injury events, providing a valuable window of opportunity to help limit and prevent some of the severe consequences with a timely treatment. Of note, it has been suggested that novel treatments for TBI should be multifactorial in nature, mimicking the body's own endogenous repair response. Whilst research has historically focused on the role of the amyloid precursor protein (APP) in the pathogenesis of Alzheimer's disease, recent advances in trauma research have demonstrated that APP offers considerable neuroprotective properties following TBI, suggesting that APP is an ideal therapeutic candidate. Its acute upregulation following TBI has been shown to serve a beneficial role following trauma and has lead to significant advances in understanding the neuroprotective and neurotrophic functions of APP and its metabolites. Research has focused predominantly on the APP derivative sAPPα, which has consistently demonstrated neuroprotective and neurotrophic functions both in vitro and in vivo following various traumatic insults. Its neuroprotective activity has been narrowed down to a 15 amino acid sequence, and this region is linked to both heparan binding and growth-factor-like properties. It has been proposed that APP binds to heparan sulfate proteoglycans to exert its neuroprotective action. APP presents us with a novel therapeutic compound that could overcome many of the challenges that have stalled development of efficacious TBI treatments previously.
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Affiliation(s)
- Stephanie Plummer
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Corinna Van den Heuvel
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Emma Thornton
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Frances Corrigan
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Roberto Cappai
- Department of Pathology, the University of Melbourne, Victoria, Australia
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45
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Fol R, Braudeau J, Ludewig S, Abel T, Weyer SW, Roederer JP, Brod F, Audrain M, Bemelmans AP, Buchholz CJ, Korte M, Cartier N, Müller UC. Viral gene transfer of APPsα rescues synaptic failure in an Alzheimer's disease mouse model. Acta Neuropathol 2016; 131:247-266. [PMID: 26538149 DOI: 10.1007/s00401-015-1498-9] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 10/07/2015] [Accepted: 10/15/2015] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease (AD) is characterized by synaptic failure, dendritic and axonal atrophy, neuronal death and progressive loss of cognitive functions. It is commonly assumed that these deficits arise due to β-amyloid accumulation and plaque deposition. However, increasing evidence indicates that loss of physiological APP functions mediated predominantly by neurotrophic APPsα produced in the non-amyloidogenic α-secretase pathway may contribute to AD pathogenesis. Upregulation of APPsα production via induction of α-secretase might, however, be problematic as this may also affect substrates implicated in tumorigenesis. Here, we used a gene therapy approach to directly overexpress APPsα in the brain using AAV-mediated gene transfer and explored its potential to rescue structural, electrophysiological and behavioral deficits in APP/PS1∆E9 AD model mice. Sustained APPsα overexpression in aged mice with already preexisting pathology and amyloidosis restored synaptic plasticity and partially rescued spine density deficits. Importantly, AAV-APPsα treatment also resulted in a functional rescue of spatial reference memory in the Morris water maze. Moreover, we demonstrate a significant reduction of soluble Aβ species and plaque load. In addition, APPsα induced the recruitment of microglia with a ramified morphology into the vicinity of plaques and upregulated IDE and TREM2 expression suggesting enhanced plaque clearance. Collectively, these data indicate that APPsα can mitigate synaptic and cognitive deficits, despite established pathology. Increasing APPsα may therefore be of therapeutic relevance for AD.
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Affiliation(s)
- Romain Fol
- INSERM U1169/MIRCen CEA, 92265, Fontenay aux Roses, France
- University Paris Sud, University Paris-Saclay, 91400, Orsay, France
- Université Paris Descartes, 75006, Paris, France
| | - Jerome Braudeau
- INSERM U1169/MIRCen CEA, 92265, Fontenay aux Roses, France
- University Paris Sud, University Paris-Saclay, 91400, Orsay, France
| | - Susann Ludewig
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, Brunswick, Germany
| | - Tobias Abel
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Sascha W Weyer
- Department of Bioinformatics and Functional Genomics, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, 69120, Heidelberg, Germany
| | - Jan-Peter Roederer
- Department of Bioinformatics and Functional Genomics, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, 69120, Heidelberg, Germany
| | - Florian Brod
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Mickael Audrain
- INSERM U1169/MIRCen CEA, 92265, Fontenay aux Roses, France
- University Paris Sud, University Paris-Saclay, 91400, Orsay, France
- Université Paris Descartes, 75006, Paris, France
| | - Alexis-Pierre Bemelmans
- University Paris Sud, University Paris-Saclay, 91400, Orsay, France
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département des Sciences du Vivant (DSV), Institut d'Imagerie Biomédicale (I2BM), Molecular Imaging Research Center (MIRCen), 92260, Fontenay aux Roses, France
- Centre National de la Recherche Scientifique (CNRS), UMR 9199, Neurodegenerative Diseases Laboratory, 92260, Fontenay aux Roses, France
| | - Christian J Buchholz
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Martin Korte
- Division of Cellular Neurobiology, Zoological Institute, TU Braunschweig, Brunswick, Germany
- Helmholtz Centre for Infection Research, AG NIND, Inhoffenstr. 7, 38124, Brunswick, Germany
| | - Nathalie Cartier
- INSERM U1169/MIRCen CEA, 92265, Fontenay aux Roses, France.
- University Paris Sud, University Paris-Saclay, 91400, Orsay, France.
| | - Ulrike C Müller
- Department of Bioinformatics and Functional Genomics, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, 69120, Heidelberg, Germany.
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Laßek M, Weingarten J, Wegner M, Volknandt W. The Amyloid Precursor Protein-A Novel Player within the Molecular Array of Presynaptic Nanomachines. Front Synaptic Neurosci 2016; 7:21. [PMID: 26834621 PMCID: PMC4719097 DOI: 10.3389/fnsyn.2015.00021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/24/2015] [Indexed: 12/27/2022] Open
Abstract
More than 20 years ago the amyloid precursor protein (APP) was identified as the precursor protein of the Aβ peptide, the main component of senile plaques in brains affected by Alzheimer’s disease (AD). The pathophysiology of AD, characterized by a massive loss of synapses, cognitive decline, and behavioral changes was in principle attributed to the accumulation of Aβ. Within the last decades, much effort has gone into understanding the molecular basis of the progression of AD. However, little is known about the actual physiological function of APPs. Allocating APP to the proteome of the structurally and functionally dynamic presynaptic active zone (PAZ) highlights APP as a hitherto unknown player within the setting of the presynapse. The molecular array of presynaptic nanomachines comprising the life cycle of synaptic vesicles, exo- and endocytosis, cytoskeletal rearrangements, and mitochondrial activity provides a balance between structural and functional maintenance and diversity. The generation of genetically designed mouse models further deciphered APP as an essential player in synapse formation and plasticity. Deletion of APP causes an age-dependent phenotype: while younger mice revealed almost no physiological impairments, this condition was changed in the elderly mice. Interestingly, the proteomic composition of neurotransmitter release sites already revealed substantial changes at young age. These changes point to a network that incorporates APP into a cluster of nanomachines. Currently, the underlying mechanism of how APP acts within these machines is still elusive. Within the scope of this review, we shall construct a network of APP interaction partners within the PAZ. Furthermore, we intend to outline how deletion of APP affects this network during space and time leading to impairments in learning and memory. These alterations may provide a molecular link to the pathogenesis of AD and the physiological function of APP in the central nervous system.
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Affiliation(s)
- Melanie Laßek
- Department of Molecular and Cellular Neurobiology, Goethe University Frankfurt Frankfurt am Main, Germany
| | - Jens Weingarten
- Department of Molecular and Cellular Neurobiology, Goethe University Frankfurt Frankfurt am Main, Germany
| | - Martin Wegner
- Department of Molecular Bioinformatics, Goethe University Frankfurt Frankfurt am Main, Germany
| | - Walter Volknandt
- Department of Molecular and Cellular Neurobiology, Goethe University Frankfurt Frankfurt am Main, Germany
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Martorana A, Di Lorenzo F, Belli L, Sancesario G, Toniolo S, Sallustio F, Sancesario GM, Koch G. Cerebrospinal Fluid Aβ42 Levels: When Physiological Become Pathological State. CNS Neurosci Ther 2015; 21:921-5. [PMID: 26555572 DOI: 10.1111/cns.12476] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/07/2015] [Accepted: 10/08/2015] [Indexed: 12/31/2022] Open
Abstract
Impaired amyloid beta (Aβ) metabolism is currently considered central to understand the pathophysiology of Alzheimer's disease (AD). Measurements of cerebrospinal fluid Aβ levels remain the most useful marker for diagnostic purposes and to individuate people at risk for AD. Despite recent advances criticized the direct role in neurodegeneration of cortical neurons, Aβ is considered responsible for synaptopathy and impairment of neurotransmission and therefore remains the major trigger of AD and future pharmacological treatment remain Aβ oriented. However, experimental and clinical findings showed that Aβ peptides could have a wider range of action responsible for cell dysfunction and for appearance of clinico-pathological entities different from AD. Such findings may induce misunderstanding of the real role played by Aβ in AD and therefore strengthen criticism on its centrality and need for CSF measurements. Aim of this review is to discuss the role of CSF Aβ levels in light of experimental, clinical pathologic, and electrophysiological results in AD and other pathological entities to put in a correct frame the value of Aβ changes.
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Affiliation(s)
- Alessandro Martorana
- Clinica Neurologica, Sytem Medicine Department, University of Rome "Tor Vergata", Rome, Italy
| | - Francesco Di Lorenzo
- Clinica Neurologica, Sytem Medicine Department, University of Rome "Tor Vergata", Rome, Italy.,Non-Invasive Brain Stimulation Unit, Department of Behavioral and Clinical Neurology, Santa Lucia Foundation IRCCS, Rome, Italy
| | - Lorena Belli
- Clinica Neurologica, Sytem Medicine Department, University of Rome "Tor Vergata", Rome, Italy
| | - Giuseppe Sancesario
- Clinica Neurologica, Sytem Medicine Department, University of Rome "Tor Vergata", Rome, Italy
| | - Sofia Toniolo
- Clinica Neurologica, Sytem Medicine Department, University of Rome "Tor Vergata", Rome, Italy
| | - Fabrizio Sallustio
- Clinica Neurologica, Sytem Medicine Department, University of Rome "Tor Vergata", Rome, Italy
| | | | - Giacomo Koch
- Non-Invasive Brain Stimulation Unit, Department of Behavioral and Clinical Neurology, Santa Lucia Foundation IRCCS, Rome, Italy
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Fanutza T, Del Prete D, Ford MJ, Castillo PE, D'Adamio L. APP and APLP2 interact with the synaptic release machinery and facilitate transmitter release at hippocampal synapses. eLife 2015; 4:e09743. [PMID: 26551565 PMCID: PMC4755753 DOI: 10.7554/elife.09743] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 11/08/2015] [Indexed: 12/16/2022] Open
Abstract
The amyloid precursor protein (APP), whose mutations cause familial Alzheimer's disease, interacts with the synaptic release machinery, suggesting a role in neurotransmission. Here we mapped this interaction to the NH2-terminal region of the APP intracellular domain. A peptide encompassing this binding domain -named JCasp- is naturally produced by a γ-secretase/caspase double-cut of APP. JCasp interferes with the APP-presynaptic proteins interaction and, if linked to a cell-penetrating peptide, reduces glutamate release in acute hippocampal slices from wild-type but not APP deficient mice, indicating that JCasp inhibits APP function.The APP-like protein-2 (APLP2) also binds the synaptic release machinery. Deletion of APP and APLP2 produces synaptic deficits similar to those caused by JCasp. Our data support the notion that APP and APLP2 facilitate transmitter release, likely through the interaction with the neurotransmitter release machinery. Given the link of APP to Alzheimer's disease, alterations of this synaptic role of APP could contribute to dementia.
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Affiliation(s)
- Tomas Fanutza
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, United States
| | - Dolores Del Prete
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, United States
| | | | - Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, United States
| | - Luciano D'Adamio
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, United States
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49
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The Association of Amyloid-β Protein Precursor With α- and β-Secretases in Mouse Cerebral Cortex Synapses Is Altered in Early Alzheimer’s Disease. Mol Neurobiol 2015; 53:5710-21. [DOI: 10.1007/s12035-015-9491-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 10/14/2015] [Indexed: 10/22/2022]
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50
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Tkatchenko AV, Tkatchenko TV, Guggenheim JA, Verhoeven VJM, Hysi PG, Wojciechowski R, Singh PK, Kumar A, Thinakaran G, Williams C. APLP2 Regulates Refractive Error and Myopia Development in Mice and Humans. PLoS Genet 2015; 11:e1005432. [PMID: 26313004 PMCID: PMC4551475 DOI: 10.1371/journal.pgen.1005432] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 07/07/2015] [Indexed: 11/19/2022] Open
Abstract
Myopia is the most common vision disorder and the leading cause of visual impairment worldwide. However, gene variants identified to date explain less than 10% of the variance in refractive error, leaving the majority of heritability unexplained (“missing heritability”). Previously, we reported that expression of APLP2 was strongly associated with myopia in a primate model. Here, we found that low-frequency variants near the 5’-end of APLP2 were associated with refractive error in a prospective UK birth cohort (n = 3,819 children; top SNP rs188663068, p = 5.0 × 10−4) and a CREAM consortium panel (n = 45,756 adults; top SNP rs7127037, p = 6.6 × 10−3). These variants showed evidence of differential effect on childhood longitudinal refractive error trajectories depending on time spent reading (gene x time spent reading x age interaction, p = 4.0 × 10−3). Furthermore, Aplp2 knockout mice developed high degrees of hyperopia (+11.5 ± 2.2 D, p < 1.0 × 10−4) compared to both heterozygous (-0.8 ± 2.0 D, p < 1.0 × 10−4) and wild-type (+0.3 ± 2.2 D, p < 1.0 × 10−4) littermates and exhibited a dose-dependent reduction in susceptibility to environmentally induced myopia (F(2, 33) = 191.0, p < 1.0 × 10−4). This phenotype was associated with reduced contrast sensitivity (F(12, 120) = 3.6, p = 1.5 × 10−4) and changes in the electrophysiological properties of retinal amacrine cells, which expressed Aplp2. This work identifies APLP2 as one of the “missing” myopia genes, demonstrating the importance of a low-frequency gene variant in the development of human myopia. It also demonstrates an important role for APLP2 in refractive development in mice and humans, suggesting a high level of evolutionary conservation of the signaling pathways underlying refractive eye development. Gene variants identified by GWAS studies to date explain only a small fraction of myopia cases because myopia represents a complex disorder thought to be controlled by dozens or even hundreds of genes. The majority of genetic variants underlying myopia seems to be of small effect and/or low frequency, which makes them difficult to identify using classical genetic approaches, such as GWAS, alone. Here, we combined gene expression profiling in a monkey model of myopia, human GWAS, and a gene-targeted mouse model of myopia to identify one of the “missing” myopia genes, APLP2. We found that a low-frequency risk allele of APLP2 confers susceptibility to myopia only in children exposed to large amounts of daily reading, thus, providing an experimental example of the long-hypothesized gene-environment interaction between nearwork and genes underlying myopia. Functional analysis of APLP2 using an APLP2 knockout mouse model confirmed functional significance of APLP2 in refractive development and implicated a potential role of synaptic transmission at the level of glycinergic amacrine cells of the retina for the development of myopia. Furthermore, mouse studies revealed that lack of Aplp2 has a dose-dependent suppressive effect on susceptibility to form-deprivation myopia, providing a potential gene-specific target for therapeutic intervention to treat myopia.
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Affiliation(s)
- Andrei V. Tkatchenko
- Department of Ophthalmology, Columbia University, New York, New York, United States of America
- Department of Pathology and Cell Biology, Columbia University, New York, New York, United States of America
- * E-mail:
| | - Tatiana V. Tkatchenko
- Department of Ophthalmology, Columbia University, New York, New York, United States of America
| | - Jeremy A. Guggenheim
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Virginie J. M. Verhoeven
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, Netherlands
| | - Pirro G. Hysi
- Department of Twin Research and Genetic Epidemiology, King’s College London School of Medicine, London, United Kingdom
| | - Robert Wojciechowski
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- Statistical Genetics Section, Inherited Disease Research Branch, National Human Genome Research Institute (NIH), Baltimore, Maryland, United States of America
| | - Pawan Kumar Singh
- Department of Ophthalmology, Wayne State University, Detroit, Michigan, United States of America
| | - Ashok Kumar
- Department of Ophthalmology, Wayne State University, Detroit, Michigan, United States of America
- Department of Anatomy and Cell Biology, Wayne State University, Detroit, Michigan, United States of America
| | - Gopal Thinakaran
- Departments of Neurobiology, Neurology, and Pathology, University of Chicago, Chicago, Illinois, United States of America
| | | | - Cathy Williams
- School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom
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