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Ono M, Ito T, Yamaki S, Hori Y, Zhou Q, Zhao X, Muramoto S, Yamamoto R, Furuyama T, Sakata-Haga H, Hatta T, Hamaguchi T, Kato N. Spatiotemporal development of the neuronal accumulation of amyloid precursor protein and the amyloid plaque formation in the brain of 3xTg-AD mice. Heliyon 2024; 10:e28821. [PMID: 38596059 PMCID: PMC11002285 DOI: 10.1016/j.heliyon.2024.e28821] [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: 08/28/2023] [Revised: 03/25/2024] [Accepted: 03/25/2024] [Indexed: 04/11/2024] Open
Abstract
The amyloid plaque is a hallmark of Alzheimer's disease. The accumulation of the amyloid precursor protein (APP) in the neuronal structure is assumed to lead to amyloid plaque formation through the excessive production of β-amyloid protein. To study the relationship between the neuronal accumulation of APP and amyloid plaque formation, we histologically analyzed their development in the different brain regions in 3xTg-AD mice, which express Swedish mutated APP (APPSWE) in the neurons. Observation throughout the brain revealed APPSWE-positive somata in the broad regions. Quantitative model analysis showed that the somatic accumulation of APPSWE developed firstly in the hippocampus from a very early age (<1 month) and proceeded slower in the isocortex. In line with this, the hippocampus was the first region to form amyloid plaques at the age of 9-12 months, while amyloid plaques were rarely observed in the isocortex. Females had more APPSWE-positive somata and plaques than males. Furthermore, amyloid plaques were observed in the lateral septum and pontine grey, which did not contain APPSWE-positive somata but only the APPSWE-positive fibers. These results suggested that neuronal accumulation of APPSWE, both in somatodendritic and axonal domains, is closely related to the formation of amyloid plaques.
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Affiliation(s)
- Munenori Ono
- Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Tetsufumi Ito
- Systems Function and Morphology, University of Toyama, Toyama, 930-0194, Japan
| | - Sachiko Yamaki
- Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Yoshie Hori
- Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Qing Zhou
- Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Xirun Zhao
- Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Shinji Muramoto
- Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Ryo Yamamoto
- Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Takafumi Furuyama
- Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Hiromi Sakata-Haga
- Department of Anatomy, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Toshihisa Hatta
- Department of Anatomy, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Tsuyoshi Hamaguchi
- Department of Neurology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
| | - Nobuo Kato
- Department of Physiology, Kanazawa Medical University, Ishikawa, 920-0293, Japan
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Cai W, Li L, Sang S, Pan X, Zhong C. Physiological Roles of β-amyloid in Regulating Synaptic Function: Implications for AD Pathophysiology. Neurosci Bull 2023; 39:1289-1308. [PMID: 36443453 PMCID: PMC10387033 DOI: 10.1007/s12264-022-00985-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 09/02/2022] [Indexed: 11/29/2022] Open
Abstract
The physiological functions of endogenous amyloid-β (Aβ), which plays important role in the pathology of Alzheimer's disease (AD), have not been paid enough attention. Here, we review the multiple physiological effects of Aβ, particularly in regulating synaptic transmission, and the possible mechanisms, in order to decipher the real characters of Aβ under both physiological and pathological conditions. Some worthy studies have shown that the deprivation of endogenous Aβ gives rise to synaptic dysfunction and cognitive deficiency, while the moderate elevation of this peptide enhances long term potentiation and leads to neuronal hyperexcitability. In this review, we provide a new view for understanding the role of Aβ in AD pathophysiology from the perspective of physiological meaning.
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Affiliation(s)
- Wenwen Cai
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Linxi Li
- Basic Medical College, Nanchang University, Nanchang, 330031, China
| | - Shaoming Sang
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Xiaoli Pan
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, 200032, China.
| | - Chunjiu Zhong
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, 200032, China.
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science & Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China.
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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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4
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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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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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6
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New insights into the role of fibroblast growth factors in Alzheimer's disease. Mol Biol Rep 2021; 49:1413-1427. [PMID: 34731369 DOI: 10.1007/s11033-021-06890-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/27/2021] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD), acknowledged as the most common progressive neurodegenerative disorder, is the leading cause of dementia in the elderly. The characteristic pathologic hallmarks of AD-including the deposition of extracellular senile plaques (SP) formation, intracellular neurofibrillary tangles, and synaptic loss, along with prominent vascular dysfunction and cognitive impairment-have been observed in patients. Fibroblast growth factors (FGFs), originally characterized as angiogenic factors, are a large family of signaling molecules that are implicated in a wide range of biological functions in brain development, maintenance and repair, as well as in the pathogenesis of brain-related disorders including AD. Many studies have focused on the implication of FGFs in AD pathophysiology. In this review, we will provide a summary of recent findings regarding the role of FGFs and their receptors in the pathogenesis of AD, and discuss the possible opportunities for targeting these molecules as novel treatment strategies in AD.
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7
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Fourriere L, Gleeson PA. Amyloid β production along the neuronal secretory pathway: Dangerous liaisons in the Golgi? Traffic 2021; 22:319-327. [PMID: 34189821 DOI: 10.1111/tra.12808] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 05/24/2021] [Accepted: 06/27/2021] [Indexed: 12/11/2022]
Abstract
β-amyloid peptides (Aβ) are generated in intracellular compartments of neurons and secreted to form cytotoxic fibrils and plaques. Dysfunctional membrane trafficking contributes to aberrant Aβ production and Alzheimer's disease. Endosomes represent one of the major sites for Aβ production and recently the Golgi has re-emerged also as a major location for amyloid precursor protein (APP) processing and Aβ production. Based on recent findings, here we propose that APP processing in the Golgi is finely tuned by segregating newly-synthesised APP and the β-secretase BACE1 within the Golgi and into distinct trans-Golgi network transport pathways. We hypothesise that there are multiple mechanisms responsible for segregating APP and BACE1 during transit through the Golgi, and that perturbation in Golgi morphology associated with Alzheimer's disease, and or changes in cholesterol metabolism associated with Alzheimer's disease risk factors, may lead to a loss of partitioning and enhanced Aβ production.
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Affiliation(s)
- Lou Fourriere
- The Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Paul A Gleeson
- The Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
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8
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Rao NR, Savas JN. Levetiracetam Treatment Normalizes Levels of Presynaptic Endocytosis Machinery and Restores Nonamyloidogenic APP Processing in App Knock-in Mice. J Proteome Res 2021; 20:3580-3589. [PMID: 34106705 PMCID: PMC8256815 DOI: 10.1021/acs.jproteome.1c00180] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Toxic amyloid-beta (Aβ) peptides, produced by sequential proteolytic cleavage of the amyloid precursor protein (APP), play a key role in the initial stage of Alzheimer's disease (AD). Increasing evidence indicates that Aβ42 induces neuronal circuit hyperexcitability in the early stages of AD pathology. As a result, researchers have investigated treatments that modulate the excitatory/inhibitory imbalance as potential AD therapies. For example, levetiracetam, an atypical antiepileptic drug used to quell hyperexcitability, has garnered recent interest in the AD field, even though its exact mechanism(s) of action remains elusive. Here, we show that in APP knock-in mouse models of amyloid pathology, chronic levetiracetam administration decreases cortical Aβ42 levels and lowers the amyloid plaque burden. In addition, using multiplexed tandem mass tag-quantitative mass spectrometry-based proteomic analysis, we determined that chronic levetiracetam administration selectively normalizes levels of presynaptic endocytic proteins. Finally, we found that levetiracetam treatment selectively lowers beta carboxyl-terminal fragment levels, while the abundance of full-length APP remains unchanged. In summary, this work reports that chronic treatment with levetiracetam serves as a useful therapeutic in AD by normalizing levels of presynaptic endocytic proteins and altering APP cleavage preference, leading to a decrease in both Aβ42 levels and the amyloid plaque burden. These novel findings provide novel evidence for the previously documented therapeutic value of levetiracetam to mitigate AD pathology.
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Affiliation(s)
- Nalini R Rao
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, United States
| | - Jeffrey N Savas
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, United States
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9
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Hark TJ, Rao NR, Castillon C, Basta T, Smukowski S, Bao H, Upadhyay A, Bomba-Warczak E, Nomura T, O'Toole ET, Morgan GP, Ali L, Saito T, Guillermier C, Saido TC, Steinhauser ML, Stowell MHB, Chapman ER, Contractor A, Savas JN. Pulse-Chase Proteomics of the App Knockin Mouse Models of Alzheimer's Disease Reveals that Synaptic Dysfunction Originates in Presynaptic Terminals. Cell Syst 2020; 12:141-158.e9. [PMID: 33326751 DOI: 10.1016/j.cels.2020.11.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 09/23/2020] [Accepted: 11/19/2020] [Indexed: 12/14/2022]
Abstract
Compromised protein homeostasis underlies accumulation of plaques and tangles in Alzheimer's disease (AD). To observe protein turnover at early stages of amyloid beta (Aβ) proteotoxicity, we performed pulse-chase proteomics on mouse brains in three genetic models of AD that knock in alleles of amyloid precursor protein (APP) prior to the accumulation of plaques and during disease progression. At initial stages of Aβ accumulation, the turnover of proteins associated with presynaptic terminals is selectively impaired. Presynaptic proteins with impaired turnover, particularly synaptic vesicle (SV)-associated proteins, have elevated levels, misfold in both a plaque-dependent and -independent manner, and interact with APP and Aβ. Concurrent with elevated levels of SV-associated proteins, we found an enlargement of the SV pool as well as enhancement of presynaptic potentiation. Together, our findings reveal that the presynaptic terminal is particularly vulnerable and represents a critical site for manifestation of initial AD etiology. A record of this paper's transparent peer review process is included in the Supplemental Information.
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Affiliation(s)
- Timothy J Hark
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Nalini R Rao
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Charlotte Castillon
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Tamara Basta
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Samuel Smukowski
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Huan Bao
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin, Madison, WI 53706, USA; Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Arun Upadhyay
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Ewa Bomba-Warczak
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Toshihiro Nomura
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Eileen T O'Toole
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Garry P Morgan
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Laith Ali
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Takashi Saito
- Laboratory of Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan; Department of Neurocognitive Science, Institute of Brain Science, Nagoya City University Graduate School of Medical Science, Nagoya, Aichi 467-8601, Japan
| | - Christelle Guillermier
- Center for NanoImaging, Brigham and Women's Hospital and Harvard Medical School, Cambridge, MA 02138, USA
| | - Takaomi C Saido
- Laboratory of Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
| | - Matthew L Steinhauser
- Center for NanoImaging, Brigham and Women's Hospital and Harvard Medical School, Cambridge, MA 02138, USA; Department of Medicine, Divisions of Genetics and Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Michael H B Stowell
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA; Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Edwin R Chapman
- Department of Neuroscience and Howard Hughes Medical Institute, University of Wisconsin, Madison, WI 53706, USA
| | - Anis Contractor
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Chicago, IL 60611, USA
| | - Jeffrey N Savas
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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10
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Kedia S, Ramakrishna P, Netrakanti PR, Singh N, Sisodia SS, Jose M, Kumar S, Mahadevan A, Ramanan N, Nadkarni S, Nair D. Alteration in synaptic nanoscale organization dictates amyloidogenic processing in Alzheimer's disease. iScience 2020; 24:101924. [PMID: 33409475 PMCID: PMC7773964 DOI: 10.1016/j.isci.2020.101924] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 11/22/2020] [Accepted: 12/07/2020] [Indexed: 01/08/2023] Open
Abstract
Despite intuitive insights into differential proteolysis of amyloid precursor protein (APP), the stochasticity behind local product formation through amyloidogenic pathway at individual synapses remain unclear. Here, we show that the major components of amyloidogenic machinery namely, APP and secretases are discretely organized into nanodomains of high local concentration compared to their immediate environment in functional zones of the synapse. Additionally, with the aid of multiple models of Alzheimer's disease (AD), we confirm that this discrete nanoscale chemical map of amyloidogenic machinery is altered at excitatory synapses. Furthermore, we provide realistic models of amyloidogenic processing in unitary vesicles originating from the endocytic zone of excitatory synapses. Thus, we show how an alteration in the stochasticity of synaptic nanoscale organization contributes to the dynamic range of C-terminal fragments β (CTFβ) production, defining the heterogeneity of amyloidogenic processing at individual synapses, leading to long-term synaptic deficits as seen in AD. Components of amyloidogenic machinery are organized into nanodomains Assembly of nanodomains differs between functional zones of the synapse Stochasticity of nanoscale organization dictates dynamic range of APP proteolysis Variability in composition of amyloidogenic machinery is associated with AD
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Affiliation(s)
- Shekhar Kedia
- Centre for Neuroscience, Indian Institute of Science, Bangalore 560012, India
| | | | | | - Nivedita Singh
- Centre for Neuroscience, Indian Institute of Science, Bangalore 560012, India
| | - Sangram S Sisodia
- Center for Molecular Neurobiology, Department of Neurobiology, The University of Chicago, IL 60637, USA
| | - Mini Jose
- Centre for Neuroscience, Indian Institute of Science, Bangalore 560012, India
| | - Sathish Kumar
- Department of Neurology, University of Bonn, Bonn 53127, Germany
| | - Anita Mahadevan
- Department of Neuropathology, NIMHANS, Bangalore 560029, India
| | | | - Suhita Nadkarni
- Indian Institute of Science Education and Research, Pune 411008, India
| | - Deepak Nair
- Centre for Neuroscience, Indian Institute of Science, Bangalore 560012, India
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11
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Pepperberg DR. Amyloid-β-Dependent Inactivation of the Mitochondrial Electron Transport Chain at Low Transmembrane Potential: An Ameliorating Process in Hypoxia-Associated Neurodegenerative Disease? J Alzheimers Dis 2020; 72:663-675. [PMID: 31640091 DOI: 10.3233/jad-190476] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Cerebral hypoperfusion-induced hypoxia, a condition that impairs oxygen utilization and thus ATP production by mitochondrial oxidative phosphorylation (oxphos), is thought to contribute to neural degeneration in Alzheimer's disease. However, hypoxia upregulates the generation of amyloid-β (Aβ), a group of peptides known to impair/inhibit the electron transport chain (ETC) of reactions that support oxphos in the inner mitochondrial membrane (IMM). This is a hypothesis paper that reconciles the hypoxia-induced upregulation of Aβ with Aβ's ETC-inhibiting action and, specifically, posits an oxphos-enhancing effect of this inhibition under conditions of newly developing or otherwise mild hypoxia. This effect is typically transient; that is, under conditions of prolonged or severe hypoxia, the oxphos-enhancing activity is overwhelmed by Aβ's well-known toxic actions on mitochondria and other cellular components. The hypothesis is motivated by evidence that the IMM transmembrane potential Ψm, an important determinant of ETC activity, exhibits heterogeneity, i.e., a range of values, among a given local population of mitochondria. It specifically proposes that during oxygen limitation, Aβ selectively inactivates ETC complexes in mitochondria that exhibit relatively low absolute values of Ψm, thereby suppressing oxygen binding and consumption by complex IV of the ETC in these mitochondria. This effect of Aβ on low-Ψm mitochondria is hypothesized to spare hypoxia-limited oxygen for oxphos-enabling utilization by the ETC of the remaining active, higher-Ψm local mitochondria, and thereby to increase overall ATP generated collectively by the local mitochondrial population, i.e., to ameliorate hypoxia-induced oxphos reduction. The protective action of Aβ hypothesized here may slow the early development of hypoxia-associated cellular deterioration/loss in Alzheimer's disease and perhaps other neurodegenerative diseases.
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Affiliation(s)
- David R Pepperberg
- Lions of Illinois Eye Research Institute, Department of Ophthalmology and Visual Sciences, Illinois Eye and Ear Infirmary, University of Illinois at Chicago, Chicago, IL, USA
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12
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Thangavelu B, Wilfred BS, Johnson D, Gilsdorf JS, Shear DA, Boutté AM. Penetrating Ballistic-Like Brain Injury Leads to MicroRNA Dysregulation, BACE1 Upregulation, and Amyloid Precursor Protein Loss in Lesioned Rat Brain Tissues. Front Neurosci 2020; 14:915. [PMID: 33071724 PMCID: PMC7530327 DOI: 10.3389/fnins.2020.00915] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/07/2020] [Indexed: 12/22/2022] Open
Abstract
Severe traumatic brain injury (TBI) is a risk factor for neurodegenerative diseases. Yet, the molecular events involving dysregulated miRNAs that may be associated with protein degradation in the brain remains elusive. Quantitation of more than 800 miRNAs was conducted using rat ipsilateral coronal brain tissues collected 1, 3, or 7 days after penetrating ballistic-like brain injury (PBBI). As a control for each time-point, Sham-operated animals received craniotomy alone. Microarray and systems biology analysis indicated that the amplitude and complexity of miRNAs affected were greatest 7 day after PBBI. Arrays and Q-PCR inferred that dysregulation of miR-135a, miR-328, miR-29c, and miR-21 were associated with altered levels of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), PSEN1, PSEN2, and amyloid precursor protein (APP) genes. These events were followed by increased levels of mature BACE1 protein and concomitant loss of full length APP within 3–7 days, then elevation of amyloid beta (Aβ)-40 7 days after PBBI. This study indicates that miRNA arrays, coupled with systems biology, may be used to guide study design prior validation of miRNA dysregulation. Associative analysis of miRNAs, mRNAs, and proteins within a proposed pathway are poised for further validation as biomarkers and therapeutic targets relevant to TBI-induced APP loss and subsequent Aβ peptide generation during neurodegeneration.
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Affiliation(s)
- Bharani Thangavelu
- Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Bernard S Wilfred
- Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - David Johnson
- Department of Pathology and Area Laboratory Services, Landstuhl Regional Medical Center, Landstuhl, Germany
| | - Janice S Gilsdorf
- Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Deborah A Shear
- Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Angela M Boutté
- Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD, United States
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13
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The Endolysosomal System and Proteostasis: From Development to Degeneration. J Neurosci 2019; 38:9364-9374. [PMID: 30381428 DOI: 10.1523/jneurosci.1665-18.2018] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/17/2018] [Accepted: 09/20/2018] [Indexed: 12/12/2022] Open
Abstract
How do neurons adapt their endolysosomal system to address the particular challenge of membrane transport across their elaborate cellular landscape and to maintain proteostasis for the lifetime of the organism? Here we review recent findings that address this central question. We discuss the cellular and molecular mechanisms of endolysosomal trafficking and the autophagy pathway in neurons, as well as their role in neuronal development and degeneration. These studies highlight the importance of understanding the basic cell biology of endolysosomal trafficking and autophagy and their roles in the maintenance of proteostasis within the context of neurons, which will be critical for developing effective therapies for various neurodevelopmental and neurodegenerative disorders.
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14
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Gaudreault R, Mousseau N. Mitigating Alzheimer’s Disease with Natural Polyphenols: A Review. Curr Alzheimer Res 2019; 16:529-543. [DOI: 10.2174/1567205016666190315093520] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 02/14/2019] [Accepted: 03/13/2019] [Indexed: 11/22/2022]
Abstract
:According to Alzheimer’s Disease International (ADI), nearly 50 million people worldwide were living with dementia in 2017, and this number is expected to triple by 2050. Despite years of research in this field, the root cause and mechanisms responsible for Alzheimer’s disease (AD) have not been fully elucidated yet. Moreover, promising preclinical results have repeatedly failed to translate into patient treatments. Until now, none of the molecules targeting AD has successfully passed the Phase III trial. Although natural molecules have been extensively studied, they normally require high concentrations to be effective; alternately, they are too large to cross the blood-brain barrier (BBB).:In this review, we report AD treatment strategies, with a virtually exclusive focus on green chemistry (natural phenolic molecules). These include therapeutic strategies for decreasing amyloid-β (Aβ) production, preventing and/or altering Aβ aggregation, and reducing oligomers cytotoxicity such as curcumin, (-)-epigallocatechin-3-gallate (EGCG), morin, resveratrol, tannic acid, and other natural green molecules. We also examine whether consideration should be given to potential candidates used outside of medicine and nutrition, through a discussion of two intermediate-sized green molecules, with very similar molecular structures and key properties, which exhibit potential in mitigating Alzheimer’s disease.
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Affiliation(s)
- Roger Gaudreault
- Department of Physics, Universit�© de Montr�©al, Case Postale 6128, Succursale Centre-ville, Montreal (QC), Canada
| | - Normand Mousseau
- Department of Physics, Universit�© de Montr�©al, Case Postale 6128, Succursale Centre-ville, Montreal (QC), Canada
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15
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Dinamarca MC, Raveh A, Schneider A, Fritzius T, Früh S, Rem PD, Stawarski M, Lalanne T, Turecek R, Choo M, Besseyrias V, Bildl W, Bentrop D, Staufenbiel M, Gassmann M, Fakler B, Schwenk J, Bettler B. Complex formation of APP with GABA B receptors links axonal trafficking to amyloidogenic processing. Nat Commun 2019; 10:1331. [PMID: 30902970 PMCID: PMC6430795 DOI: 10.1038/s41467-019-09164-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 02/21/2019] [Indexed: 12/30/2022] Open
Abstract
GABAB receptors (GBRs) are key regulators of synaptic release but little is known about trafficking mechanisms that control their presynaptic abundance. We now show that sequence-related epitopes in APP, AJAP-1 and PIANP bind with nanomolar affinities to the N-terminal sushi-domain of presynaptic GBRs. Of the three interacting proteins, selectively the genetic loss of APP impaired GBR-mediated presynaptic inhibition and axonal GBR expression. Proteomic and functional analyses revealed that APP associates with JIP and calsyntenin proteins that link the APP/GBR complex in cargo vesicles to the axonal trafficking motor. Complex formation with GBRs stabilizes APP at the cell surface and reduces proteolysis of APP to Aβ, a component of senile plaques in Alzheimer's disease patients. Thus, APP/GBR complex formation links presynaptic GBR trafficking to Aβ formation. Our findings support that dysfunctional axonal trafficking and reduced GBR expression in Alzheimer's disease increases Aβ formation.
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Affiliation(s)
- Margarita C Dinamarca
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Adi Raveh
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Andy Schneider
- Faculty of Medicine, Institute of Physiology, University of Freiburg, Hermann-Herder-Str. 7, 79104, Freiburg, Germany
| | - Thorsten Fritzius
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Simon Früh
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Pascal D Rem
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Michal Stawarski
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Txomin Lalanne
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Rostislav Turecek
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
- Institute of Experimental Medicine, ASCR, Vı´denska´ 1083, 14220, Prague 4-Krc, Czech Republic
| | - Myeongjeong Choo
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Valérie Besseyrias
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Wolfgang Bildl
- Faculty of Medicine, Institute of Physiology, University of Freiburg, Hermann-Herder-Str. 7, 79104, Freiburg, Germany
| | - Detlef Bentrop
- Faculty of Medicine, Institute of Physiology, University of Freiburg, Hermann-Herder-Str. 7, 79104, Freiburg, Germany
| | - Matthias Staufenbiel
- Department of Cellular Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Strasse 27, 72076, Tübingen, Germany
| | - Martin Gassmann
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland
| | - Bernd Fakler
- Faculty of Medicine, Institute of Physiology, University of Freiburg, Hermann-Herder-Str. 7, 79104, Freiburg, Germany
- Signalling Research Centers BIOSS and CIBSS, University of Freiburg, Schänzlestr. 18, 79104, Freiburg, Germany
| | - Jochen Schwenk
- Faculty of Medicine, Institute of Physiology, University of Freiburg, Hermann-Herder-Str. 7, 79104, Freiburg, Germany.
- Signalling Research Centers BIOSS and CIBSS, University of Freiburg, Schänzlestr. 18, 79104, Freiburg, Germany.
| | - Bernhard Bettler
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50/70, 4056, Basel, Switzerland.
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16
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Andrew RJ, Fisher K, Heesom KJ, Kellett KAB, Hooper NM. Quantitative interaction proteomics reveals differences in the interactomes of amyloid precursor protein isoforms. J Neurochem 2019; 149:399-412. [PMID: 30664241 DOI: 10.1111/jnc.14666] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/21/2018] [Accepted: 01/16/2019] [Indexed: 02/04/2023]
Abstract
The generation of the amyloid-β (Aβ) peptides from the amyloid precursor protein (APP) through sequential proteolysis by β- and γ-secretases is a key pathological event in the initiation and propagation of Alzheimer's disease. Aβ and the transcriptionally active APP intracellular domain are generated preferentially from the APP695 isoform compared to the longer APP751 isoform. As the Aβ and amyloid precursor protein intracellular domain produced from cleavage of APP695 and APP751 are identical we hypothesised that the two isoforms have differences within their interactomes which mediate the differential processing of the two isoforms. To investigate this, we applied a proteomics-based approach to identify differences in the interactomes of the APP695 and APP751 isoforms. Using stable isotope labelling of amino acids in cell culture and quantitative proteomics, we compared the interactomes of APP695 and APP751 expressed in human SH-SY5Y cells. Through this approach, we identified enrichment of proteins involved in mitochondrial function, the nuclear pore and nuclear transport specifically in the APP695 interactome. Further interrogation of the APP interactome and subsequent experimental validation (co-immunoprecipitation and siRNA knockdown) revealed GAP43 as a specific modulator of APP751 proteolysis, altering Aβ generation. Our data indicate that interrogation of the APP interactome can be exploited to identify proteins which influence APP proteolysis and Aβ production in an isoform dependent-manner. Cover Image for this issue: doi: 10.1111/jnc.14504.
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Affiliation(s)
- Robert J Andrew
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Kate Fisher
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Kate J Heesom
- Proteomics Facility, Faculty of Medical and Veterinary Sciences, University of Bristol, Bristol, UK
| | - Katherine A B Kellett
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Nigel M Hooper
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, School of Biological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
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17
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Martinsson I, Capetillo-Zarate E, Faideau M, Willén K, Esteras N, Frykman S, Tjernberg LO, Gouras GK. APP depletion alters selective pre- and post-synaptic proteins. Mol Cell Neurosci 2019; 95:86-95. [PMID: 30763689 DOI: 10.1016/j.mcn.2019.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/30/2019] [Accepted: 02/09/2019] [Indexed: 12/30/2022] Open
Abstract
The normal role of Alzheimer's disease (AD)-linked amyloid precursor protein (APP) in the brain remains incompletely understood. Previous studies have reported that lack of APP has detrimental effects on spines and electrophysiological parameters. APP has been described to be important in synaptic pruning during development. The effect of APP knockout on mature synapses is complicated by this role in development. We previously reported on differential changes in synaptic proteins and receptors in APP mutant AD transgenic compared to wild-type neurons, which revealed selective decreases in levels of pre- and post-synaptic proteins, including of surface glutamate receptors. In the present study, we undertook a similar analysis of synaptic composition but now in APP knockout compared to wild-type mouse neurons. Here we demonstrate alterations in levels of selective pre- and post-synaptic proteins and receptors in APP knockout compared to wild-type mouse primary neurons in culture and brains of mice in youth and adulthood. Remarkably, we demonstrate selective increases in levels of synaptic proteins, such as GluA1, in neurons with APP knockout and with RNAi knockdown, which tended to be opposite to the reductions seen in AD transgenic APP mutant compared to wild-type neurons. These data reinforce that APP is important for the normal composition of synapses.
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Affiliation(s)
- Isak Martinsson
- Experimental Dementia Research Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Estibaliz Capetillo-Zarate
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY, USA; Achucarro Basque Center for Neuroscience, CIBERNED and Departamento de Neurociencias, Universidad del País Vasco. Leioa, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Mathilde Faideau
- Experimental Dementia Research Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Katarina Willén
- Experimental Dementia Research Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Noemi Esteras
- Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY, USA
| | - Susanne Frykman
- Karolinska Institute, Dept. of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Division of Neurogeriatrics, Huddinge, Sweden
| | - Lars O Tjernberg
- Karolinska Institute, Dept. of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Division of Neurogeriatrics, Huddinge, Sweden
| | - Gunnar K Gouras
- Experimental Dementia Research Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden; Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY, USA.
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18
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Walter S, Jumpertz T, Hüttenrauch M, Ogorek I, Gerber H, Storck SE, Zampar S, Dimitrov M, Lehmann S, Lepka K, Berndt C, Wiltfang J, Becker-Pauly C, Beher D, Pietrzik CU, Fraering PC, Wirths O, Weggen S. The metalloprotease ADAMTS4 generates N-truncated Aβ4-x species and marks oligodendrocytes as a source of amyloidogenic peptides in Alzheimer's disease. Acta Neuropathol 2019; 137:239-257. [PMID: 30426203 DOI: 10.1007/s00401-018-1929-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 10/17/2018] [Accepted: 11/04/2018] [Indexed: 02/06/2023]
Abstract
Brain accumulation and aggregation of amyloid-β (Aβ) peptides is a critical step in the pathogenesis of Alzheimer's disease (AD). Full-length Aβ peptides (mainly Aβ1-40 and Aβ1-42) are produced through sequential proteolytic cleavage of the amyloid precursor protein (APP) by β- and γ-secretases. However, studies of autopsy brain samples from AD patients have demonstrated that a large fraction of insoluble Aβ peptides are truncated at the N-terminus, with Aβ4-x peptides being particularly abundant. Aβ4-x peptides are highly aggregation prone, but their origin and any proteases involved in their generation are unknown. We have identified a recognition site for the secreted metalloprotease ADAMTS4 (a disintegrin and metalloproteinase with thrombospondin motifs 4) in the Aβ peptide sequence, which facilitates Aβ4-x peptide generation. Inducible overexpression of ADAMTS4 in HEK293 cells resulted in the secretion of Aβ4-40 but unchanged levels of Aβ1-x peptides. In the 5xFAD mouse model of amyloidosis, Aβ4-x peptides were present not only in amyloid plaque cores and vessel walls, but also in white matter structures co-localized with axonal APP. In the ADAMTS4-/- knockout background, Aβ4-40 levels were reduced confirming a pivotal role of ADAMTS4 in vivo. Surprisingly, in the adult murine brain, ADAMTS4 was exclusively expressed in oligodendrocytes. Cultured oligodendrocytes secreted a variety of Aβ species, but Aβ4-40 peptides were absent in cultures derived from ADAMTS4-/- mice indicating that the enzyme was essential for Aβ4-x production in this cell type. These findings establish an enzymatic mechanism for the generation of Aβ4-x peptides. They further identify oligodendrocytes as a source of these highly amyloidogenic Aβ peptides.
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19
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Sun M, Huang C, Wang H, Zhang H. Par3 regulates polarized convergence between APP and BACE1 in hippocampal neurons. Neurobiol Aging 2019; 77:87-93. [PMID: 30784815 DOI: 10.1016/j.neurobiolaging.2019.01.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 01/07/2019] [Accepted: 01/22/2019] [Indexed: 12/25/2022]
Abstract
The convergence between amyloid precursor protein (APP) and its β-secretase β-site APP cleaving enzyme 1 (BACE1) is a prerequisite for the generation of β-amyloid peptide, a key pathogenic agent for Alzheimer's disease. Yet the underlying molecular mechanisms regulating their convergence remain unclear. Here, we show that the polarity protein partitioning-defective 3 (Par3) regulates the polarized convergence between APP and BACE1 in hippocampal neurons. Par3 forms a complex with BACE1 through its first PDZ domain, which is important for regulating BACE1 endosome-to-TGN trafficking. In the absence of Par3, there is an increase in the convergence between internalized APP and BACE1. In hippocampal neurons, loss of Par3 leads to increased APP and BACE1 convergence in axons but not in dendrites. This polarized convergence mainly occurs in retrograde or stalled axonal late endocytic organelles and is likely due to compartment-specific regulation of APP trafficking by Par3. Together, our data show a novel function for Par3 in regulating polarized convergence between APP and BACE1 in hippocampal neurons.
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Affiliation(s)
- Miao Sun
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA.
| | - Chengyu Huang
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, Jiangsu, China
| | - Hui Wang
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA; Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, Jiangsu, China
| | - Huaye Zhang
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA.
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20
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Kim YJ, Yoo JY, Kim OS, Kim HB, Ryu J, Kim HS, Lee JH, Yoo HI, Song DY, Baik TK, Woo RS. Neuregulin 1 regulates amyloid precursor protein cell surface expression and non-amyloidogenic processing. J Pharmacol Sci 2018; 137:146-153. [DOI: 10.1016/j.jphs.2018.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 05/06/2018] [Accepted: 05/17/2018] [Indexed: 01/11/2023] Open
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21
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Willén K, Sroka A, Takahashi RH, Gouras GK. Heterogeneous Association of Alzheimer's Disease-Linked Amyloid-β and Amyloid-β Protein Precursor with Synapses. J Alzheimers Dis 2018; 60:511-524. [PMID: 28869466 PMCID: PMC5611798 DOI: 10.3233/jad-170262] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Alzheimer’s disease (AD) is increasingly viewed as a disease of synapses. Loss of synapses correlates better with cognitive decline than amyloid plaques and neurofibrillary tangles, the hallmark neuropathological lesions of AD. Soluble forms of amyloid-β (Aβ) have emerged as mediators of synapse dysfunction. Aβ binds to, accumulates, and aggregates in synapses. However, the anatomical and neurotransmitter specificity of Aβ and the amyloid-β protein precursor (AβPP) in AD remain poorly understood. In addition, the relative roles of Aβ and AβPP in the development of AD, at pre- versus post-synaptic compartments and axons versus dendrites, respectively, remain unclear. Here we use immunogold electron microscopy and confocal microscopy to provide evidence for heterogeneity in the localization of Aβ/AβPP. We demonstrate that Aβ binds to a subset of synapses in cultured neurons, with preferential binding to glutamatergic compared to GABAergic neurons. We also highlight the challenge of defining pre- versus post-synaptic localization of this binding by confocal microscopy. Further, endogenous Aβ42 accumulates in both glutamatergic and GABAergic AβPP/PS1 transgenic primary neurons, but at varying levels. Moreover, upon knock-out of presenilin 1 or inhibition of γ-secretase AβPP C-terminal fragments accumulate both pre- and post-synaptically; however earlier pre-synaptically, consistent with a higher rate of AβPP processing in axons. A better understanding of the synaptic and anatomical selectivity of Aβ/AβPP in AD can be important for the development of more effective new therapies for this major disease of aging.
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Affiliation(s)
- Katarina Willén
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Agnieszka Sroka
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | | | - Gunnar K Gouras
- Department of Experimental Medical Science, Lund University, Lund, Sweden
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22
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Trans-Synaptic Spread of Amyloid- β in Alzheimer's Disease: Paths to β-Amyloidosis. Neural Plast 2017; 2017:5281829. [PMID: 29435372 PMCID: PMC5757149 DOI: 10.1155/2017/5281829] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 11/15/2017] [Accepted: 11/27/2017] [Indexed: 01/10/2023] Open
Abstract
Neuronal activity has a strong causal role in the production and release of the neurotoxic β-amyloid peptide (Aβ). Because of this close link, gradual accumulation of Aβ into amyloid plaques has been reported in brain areas with intense neuronal activity, including cortical regions that display elevated activation at resting state. However, the link between Aβ and activity is not always linear and recent studies report exceptions to the view of “more activity, more plaques.” Here, we review the literature about the activity-dependent production of Aβ in both human cases and AD models and focus on the evidences that brain regions with elevated convergence of synaptic connections (herein referred to as brain nodes) are particularly vulnerable to Aβ accumulation. Next, we will examine data supporting the hypothesis that, since Aβ is released from synaptic terminals, β-amyloidosis can spread in AD brain by advancing through synaptically connected regions, which makes brain nodes vulnerable to Aβ accumulation. Finally, we consider possible mechanisms that account for β-amyloidosis progression through synaptically linked regions.
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23
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Polanco JC, Li C, Bodea LG, Martinez-Marmol R, Meunier FA, Götz J. Amyloid-β and tau complexity — towards improved biomarkers and targeted therapies. Nat Rev Neurol 2017; 14:22-39. [DOI: 10.1038/nrneurol.2017.162] [Citation(s) in RCA: 235] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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24
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Parenti N, Del Grosso A, Antoni C, Cecchini M, Corradetti R, Pavone FS, Calamai M. Direct imaging of APP proteolysis in living cells. PeerJ 2017; 5:e3086. [PMID: 28413720 PMCID: PMC5391788 DOI: 10.7717/peerj.3086] [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: 10/06/2016] [Accepted: 02/13/2017] [Indexed: 11/20/2022] Open
Abstract
Alzheimer’s disease is a multifactorial disorder caused by the interaction of genetic, epigenetic and environmental factors. The formation of cytotoxic oligomers consisting of Aβ peptide is widely accepted as being one of the main key events triggering the development of Alzheimer’s disease. Aβ peptide production results from the specific proteolytic processing of the amyloid precursor protein (APP). Deciphering the factors governing the activity of the secretases responsible for the cleavage of APP is still a critical issue. Kits available commercially measure the enzymatic activity of the secretases from cells lysates, in vitro. By contrast, we have developed a prototypal rapid bioassay that provides visible information on the proteolytic processing of APP directly in living cells. APP was fused to a monomeric variant of the green fluorescent protein and a monomeric variant of the red fluorescent protein at the C-terminal and N-terminal (mChAPPmGFP), respectively. Changes in the proteolytic processing rate in transfected human neuroblastoma and rat neuronal cells were imaged with confocal microscopy as changes in the red/green fluorescence intensity ratio. The significant decrease in the mean red/green ratio observed in cells over-expressing the β-secretase BACE1, or the α-secretase ADAM10, fused to a monomeric blue fluorescent protein confirms that the proteolytic site is still accessible. Specific siRNA was used to evaluate the contribution of endogenous BACE1. Interestingly, we found that the degree of proteolytic processing of APP is not completely homogeneous within the same single cell, and that there is a high degree of variability between cells of the same type. We were also able to follow with a fluorescence spectrometer the changes in the red emission intensity of the extracellular medium when BACE1 was overexpressed. This represents a complementary approach to fluorescence microscopy for rapidly detecting changes in the proteolytic processing of APP in real time. In order to allow the discrimination between the α- and the β-secretase activity, we have created a variant of mChAPPmGFP with a mutation that inhibits the α-secretase cleavage without perturbing the β-secretase processing. Moreover, we obtained a quantitatively robust estimate of the changes in the red/green ratio for the above conditions by using a flow cytometer able to simultaneously excite and measure the red and green fluorescence. Our novel approach lay the foundation for a bioassay suitable to study the effect of drugs or particular conditions, to investigate in an unbiased way the the proteolytic processing of APP in single living cells in order, and to elucidate the causes of the variability and the factors driving the processing of APP.
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Affiliation(s)
- Niccoló Parenti
- European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Florence, Italy.,Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Ambra Del Grosso
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Pisa, Italy
| | - Claudia Antoni
- European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Florence, Italy
| | - Marco Cecchini
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Pisa, Italy
| | - Renato Corradetti
- Department of Neuroscience, Psychology, Drug Research and Child Health, University of Florence, Florence, Italy
| | - Francesco S Pavone
- European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Florence, Italy.,National Institute of Optics, National Research Council of Italy (CNR), Florence, Italy
| | - Martino Calamai
- European Laboratory for Non-linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Florence, Italy.,National Institute of Optics, National Research Council of Italy (CNR), Florence, Italy
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25
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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: 387] [Impact Index Per Article: 55.3] [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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26
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Nigam SM, Xu S, Ackermann F, Gregory JA, Lundkvist J, Lendahl U, Brodin L. Endogenous APP accumulates in synapses after BACE1 inhibition. Neurosci Res 2016; 109:9-15. [DOI: 10.1016/j.neures.2016.02.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 02/11/2016] [Accepted: 02/15/2016] [Indexed: 10/22/2022]
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Yan R, Fan Q, Zhou J, Vassar R. Inhibiting BACE1 to reverse synaptic dysfunctions in Alzheimer's disease. Neurosci Biobehav Rev 2016; 65:326-40. [PMID: 27044452 PMCID: PMC4856578 DOI: 10.1016/j.neubiorev.2016.03.025] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 03/25/2016] [Accepted: 03/29/2016] [Indexed: 12/21/2022]
Abstract
Over the past two decades, many studies have identified significant contributions of toxic β-amyloid peptides (Aβ) to the etiology of Alzheimer's disease (AD), which is the most common age-dependent neurodegenerative disease. AD is also recognized as a disease of synaptic failure. Aβ, generated by sequential proteolytic cleavages of amyloid precursor protein (APP) by BACE1 and γ-secretase, is one of major culprits that cause this failure. In this review, we summarize current findings on how BACE1-cleaved APP products impact learning and memory through proteins localized on glutamatergic, GABAergic, and dopaminergic synapses. Considering the broad effects of Aβ on all three types of synapses, BACE1 inhibition emerges as a practical approach for ameliorating Aβ-mediated synaptic dysfunctions. Since BACE1 inhibitory drugs are currently in clinical trials, this review also discusses potential complications arising from BACE1 inhibition. We emphasize that the benefits of BACE1 inhibitory drugs will outweigh the concerns.
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Affiliation(s)
- Riqiang Yan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
| | - Qingyuan Fan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - John Zhou
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Robert Vassar
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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28
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Yuan P, Grutzendler J. Attenuation of β-Amyloid Deposition and Neurotoxicity by Chemogenetic Modulation of Neural Activity. J Neurosci 2016; 36:632-41. [PMID: 26758850 PMCID: PMC4710779 DOI: 10.1523/jneurosci.2531-15.2016] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 10/22/2015] [Accepted: 12/02/2015] [Indexed: 11/21/2022] Open
Abstract
Aberrant neural hyperactivity has been observed in early stages of Alzheimer's disease (AD) and may be a driving force in the progression of amyloid pathology. Evidence for this includes the findings that neural activity may modulate β-amyloid (Aβ) peptide secretion and experimental stimulation of neural activity can increase amyloid deposition. However, whether long-term attenuation of neural activity prevents the buildup of amyloid plaques and associated neural pathologies remains unknown. Using viral-mediated delivery of designer receptors exclusively activated by designer drugs (DREADDs), we show in two AD-like mouse models that chronic intermittent increases or reductions of activity have opposite effects on Aβ deposition. Neural activity reduction markedly decreases Aβ aggregation in regions containing axons or dendrites of DREADD-expressing neurons, suggesting the involvement of synaptic and nonsynaptic Aβ release mechanisms. Importantly, activity attenuation is associated with a reduction in axonal dystrophy and synaptic loss around amyloid plaques. Thus, modulation of neural activity could constitute a potential therapeutic strategy for ameliorating amyloid-induced pathology in AD. SIGNIFICANCE STATEMENT A novel chemogenetic approach to upregulate and downregulate neuronal activity in Alzheimer's disease (AD) mice was implemented. This led to the first demonstration that chronic intermittent attenuation of neuronal activity in vivo significantly reduces amyloid deposition. The study also demonstrates that modulation of β-amyloid (Aβ) release can occur at both axonal and dendritic fields, suggesting the involvement of synaptic and nonsynaptic Aβ release mechanisms. Activity reductions also led to attenuation of the synaptic pathology associated with amyloid plaques. Therefore, chronic attenuation of neuronal activity could constitute a novel therapeutic approach for AD.
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Affiliation(s)
- Peng Yuan
- Departments of Neurology and Neuroscience, Yale University, New Haven, Connecticut 06510
| | - Jaime Grutzendler
- Departments of Neurology and Neuroscience, Yale University, New Haven, Connecticut 06510
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29
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Visualizing APP and BACE-1 approximation in neurons yields insight into the amyloidogenic pathway. Nat Neurosci 2015; 19:55-64. [PMID: 26642089 PMCID: PMC4782935 DOI: 10.1038/nn.4188] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 11/04/2015] [Indexed: 11/24/2022]
Abstract
Cleavage of APP (amyloid precursor protein) by BACE-1 (β-site APP cleaving enzyme-1) is the rate-limiting step in amyloid-beta (Aβ) production and a neuropathologic hallmark of Alzheimer's disease (AD); thus physical approximation of this substrate-enzyme pair is a critical event with broad biological and therapeutic implications. Despite much research, neuronal locales of APP/BACE-1 convergence and APP-cleavage remain unclear. Here we report an optical assay – based on fluorescence complementation – to visualize in-cellulo APP/BACE-1 interactions as a simple on/off signal. Combined with other assays tracking the fate of internalized APP in hippocampal neurons, we found that APP/BACE-1 interact in both biosynthetic and endocytic compartments; particularly along recycling-microdomains such as dendritic spines and presynaptic boutons. In axons, APP and BACE-1 are co-transported, and also interact during transit. Finally, our assay reveals that the AD-protective “Icelandic” mutation greatly attenuates APP/BACE-1 interactions, suggesting a mechanistic basis for protection. Collectively, the data challenge canonical models and provide concrete insights into long-standing controversies in the field.
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30
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van der Kant R, Goldstein LSB. Cellular functions of the amyloid precursor protein from development to dementia. Dev Cell 2015; 32:502-15. [PMID: 25710536 DOI: 10.1016/j.devcel.2015.01.022] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Amyloid precursor protein (APP) is a key player in Alzheimer's disease (AD). The Aβ fragments of APP are the major constituent of AD-associated amyloid plaques, and mutations or duplications of the gene coding for APP can cause familial AD. Here we review the roles of APP in neuronal development, signaling, intracellular transport, and other aspects of neuronal homeostasis. We suggest that APP acts as a signaling nexus that transduces information about a range of extracellular conditions, including neuronal damage, to induction of intracellular signaling events. Subtle disruptions of APP signaling functions may be major contributors to AD-causing neuronal dysfunction.
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Affiliation(s)
- Rik van der Kant
- Department of Cellular and Molecular Medicine, University of California-San Diego, La Jolla, CA 92093, USA.
| | - Lawrence S B Goldstein
- Department of Cellular and Molecular Medicine, University of California-San Diego, La Jolla, CA 92093, USA.
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31
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Muresan V, Ladescu Muresan Z. Amyloid-β precursor protein: Multiple fragments, numerous transport routes and mechanisms. Exp Cell Res 2015; 334:45-53. [PMID: 25573596 DOI: 10.1016/j.yexcr.2014.12.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 12/26/2014] [Indexed: 02/01/2023]
Abstract
This review provides insight into the intraneuronal transport of the Amyloid-β Precursor Protein (APP), the prototype of an extensively posttranslationally modified and proteolytically cleaved transmembrane protein. Uncovering the intricacies of APP transport proves to be a challenging endeavor of cell biology research, deserving increased priority, since APP is at the core of the pathogenic process in Alzheimer's disease. After being synthesized in the endoplasmic reticulum in the neuronal soma, APP enters the intracellular transport along the secretory, endocytic, and recycling routes. Along these routes, APP undergoes cleavage into defined sets of fragments, which themselves are transported - mostly independently - to distinct sites in neurons, where they exert their functions. We review the currently known routes and mechanisms of transport of full-length APP, and of APP fragments, commenting largely on the experimental challenges posed by studying transport of extensively cleaved proteins. The review emphasizes the interrelationships between the proteolytic and posttranslational modifications, the intracellular transport, and the functions of the APP species. A goal remaining to be addressed in the future is the incorporation of the various views on APP transport into a coherent picture. In this review, the disease context is only marginally addressed; the focus is on the basic biology of APP transport under normal conditions. As shown, the studies of APP transport uncovered numerous mechanisms of transport, some of them conventional, and others, novel, awaiting exploration.
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Affiliation(s)
- Virgil Muresan
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07101-1709, USA.
| | - Zoia Ladescu Muresan
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07101-1709, USA.
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32
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Abstract
Many lines of evidence support that β-amyloid (Aβ) peptides play an important role in Alzheimer's disease (AD), the most common cause of dementia. But despite much effort the molecular mechanisms of how Aβ contributes to AD remain unclear. While Aβ is generated from its precursor protein throughout life, the peptide is best known as the main component of amyloid plaques, the neuropathological hallmark of AD. Reduction in Aβ has been the major target of recent experimental therapies against AD. Unfortunately, human clinical trials targeting Aβ have not shown the hoped-for benefits. Thus, doubts have been growing about the role of Aβ as a therapeutic target. Here we review evidence supporting the involvement of Aβ in AD, highlight the importance of differentiating between various forms of Aβ, and suggest that a better understanding of Aβ's precise pathophysiological role in the disease is important for correctly targeting it for potential future therapy.
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Affiliation(s)
- Gunnar K. Gouras
- />Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Tomas T. Olsson
- />Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Oskar Hansson
- />Clinical Memory Research Unit, Clinical Sciences Malmö, Lund University, Lund, Sweden
- />Memory Clinic, Skåne University Hospital, Skåne, Sweden
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