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APP Receptor? To Be or Not To Be. Trends Pharmacol Sci 2016; 37:390-411. [PMID: 26837733 DOI: 10.1016/j.tips.2016.01.005] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/07/2016] [Accepted: 01/11/2016] [Indexed: 11/22/2022]
Abstract
Amyloid precursor protein (APP) and its metabolites play a key role in Alzheimer's disease pathogenesis. The idea that APP may function as a receptor has gained momentum based on its structural similarities to type I transmembrane receptors and the identification of putative APP ligands. We review the recent experimental evidence in support of this notion and discuss how this concept is viewed in the field. Specifically, we focus on the structural and functional characteristics of APP as a cell surface receptor, and on its interaction with adaptors and signaling proteins. We also address the importance of APP function as a receptor in Alzheimer's disease etiology and discuss how this function might be potentially important for the development of novel therapeutic approaches.
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52
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Wang X, Ma Y, Zhao Y, Chen Y, Hu Y, Chen C, Shao Y, Xue L. APLP1 promotes dFoxO-dependent cell death in Drosophila. Apoptosis 2016; 20:778-86. [PMID: 25740230 DOI: 10.1007/s10495-015-1097-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The amyloid precursor like protein-1 (APLP1) belongs to the amyloid precursor protein family that also includes the amyloid precursor protein (APP) and the amyloid precursor like protein-2 (APLP2). Though the three proteins share similar structures and undergo the same cleavage processing by α-, β- and γ-secretases, APLP1 shows divergent subcellular localization from that of APP and APLP2, and thus, may perform distinct roles in vivo. While extensive studies have been focused on APP, which is implicated in the pathogenesis of Alzheimer's disease, the functions of APLP1 remain largely elusive. Here we report that the expression of APLP1 in Drosophila induces cell death and produces developmental defects in wing and thorax. This function of APLP1 depends on the transcription factor dFoxO, as the depletion of dFoxO abrogates APLP1-induced cell death and adult defects. Consistently, APLP1 up-regulates the transcription of dFoxO target hid and reaper-two well known pro-apoptotic genes. Thus, the present study provides the first in vivo evidence that APLP1 is able to induce cell death, and that FoxO is a crucial downstream mediator of APLP1's activity.
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Affiliation(s)
- Xingjun Wang
- Institute of Intervention Vessel, Shanghai 10th People's Hospital, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China,
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53
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Stanga S, Zanou N, Audouard E, Tasiaux B, Contino S, Vandermeulen G, René F, Loeffler JP, Clotman F, Gailly P, Dewachter I, Octave JN, Kienlen-Campard P. APP-dependent glial cell line-derived neurotrophic factor gene expression drives neuromuscular junction formation. FASEB J 2015; 30:1696-711. [PMID: 26718890 DOI: 10.1096/fj.15-278739] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 12/08/2015] [Indexed: 12/13/2022]
Abstract
Besides its crucial role in the pathogenesis of Alzheimer's disease, the knowledge of amyloid precursor protein (APP) physiologic functions remains surprisingly scarce. Here, we show that APP regulates the transcription of the glial cell line-derived neurotrophic factor (GDNF). APP-dependent regulation of GDNF expression affects muscle strength, muscular trophy, and both neuronal and muscular differentiation fundamental for neuromuscular junction (NMJ) maturation in vivo In a nerve-muscle coculture model set up to modelize NMJ formation in vitro, silencing of muscular APP induces a 30% decrease in secreted GDNF levels and a 40% decrease in the total number of NMJs together with a significant reduction in the density of acetylcholine vesicles at the presynaptic site and in neuronal maturation. These defects are rescued by GDNF expression in muscle cells in the conditions where muscular APP has been previously silenced. Expression of GDNF in muscles of amyloid precursor protein null mice corrected the aberrant synaptic morphology of NMJs. Our findings highlight for the first time that APP-dependent GDNF expression drives the process of NMJ formation, providing new insights into the link between APP gene regulatory network and physiologic functions.-Stanga, S., Zanou, N., Audouard, E., Tasiaux, B., Contino, S., Vandermeulen, G., René, F., Loeffler, J.-P., Clotman, F., Gailly, P., Dewachter, I., Octave, J.-N., Kienlen-Campard, P. APP-dependent glial cell line-derived neurotrophic factor gene expression drives neuromuscular junction formation.
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Affiliation(s)
- Serena Stanga
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Nadège Zanou
- Laboratory of Cell Physiology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Emilie Audouard
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Bernadette Tasiaux
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Sabrina Contino
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Gaëlle Vandermeulen
- Advanced Drug Delivery and Biomaterials, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium; and
| | - Frédérique René
- Institut National de la Santé et de la Recherche Médicale, Unité 1118 Mécanismes Centraux et Périphériques de la Neurodégénérescence, Université de Strasbourg, Strasbourg Cedex, France
| | - Jean-Philippe Loeffler
- Institut National de la Santé et de la Recherche Médicale, Unité 1118 Mécanismes Centraux et Périphériques de la Neurodégénérescence, Université de Strasbourg, Strasbourg Cedex, France
| | - Frédéric Clotman
- Laboratory of Neural Differentiation, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Philippe Gailly
- Laboratory of Cell Physiology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Ilse Dewachter
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Jean-Noël Octave
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Pascal Kienlen-Campard
- Alzheimer Research Group, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium;
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Decock M, El Haylani L, Stanga S, Dewachter I, Octave JN, Smith SO, Constantinescu SN, Kienlen-Campard P. Analysis by a highly sensitive split luciferase assay of the regions involved in APP dimerization and its impact on processing. FEBS Open Bio 2015; 5:763-73. [PMID: 26500837 PMCID: PMC4588712 DOI: 10.1016/j.fob.2015.09.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 08/07/2015] [Accepted: 09/01/2015] [Indexed: 12/27/2022] Open
Abstract
Amyloid precursor protein (APP) dimerizes more than its C-terminal fragments in cells. Mutations of membrane GXXXG motifs affect Aβ production but not APP dimerization. Deletion of the APP intracellular domain increases APP dimerization.
Alzheimer’s disease (AD) is a neurodegenerative disease that causes progressive loss of cognitive functions, leading to dementia. Two types of lesions are found in AD brains: neurofibrillary tangles and senile plaques. The latter are composed mainly of the β-amyloid peptide (Aβ) generated by amyloidogenic processing of the amyloid precursor protein (APP). Several studies have suggested that dimerization of APP is closely linked to Aβ production. Nevertheless, the mechanisms controlling APP dimerization and their role in APP function are not known. Here we used a new luciferase complementation assay to analyze APP dimerization and unravel the involvement of its three major domains: the ectodomain, the transmembrane domain and the intracellular domain. Our results indicate that within cells full-length APP dimerizes more than its α and β C-terminal fragments, confirming the pivotal role of the ectodomain in this process. Dimerization of the APP transmembrane (TM) domain has been reported to regulate processing at the γ-cleavage site. We show that both non-familial and familial AD mutations in the TM GXXXG motifs strongly modulate Aβ production, but do not consistently change dimerization of the C-terminal fragments. Finally, we found for the first time that removal of intracellular domain strongly increases APP dimerization. Increased APP dimerization is linked to increased non-amyloidogenic processing.
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Key Words
- AD, Alzheimer’s disease
- AICD, APP intracellular domain
- APP
- APP, amyloid precursor protein
- Alzheimer disease
- Amyloid beta peptide
- Aβ, β-amyloid peptide
- CHO, chinese hamster ovary
- CTF, C-terminal fragment
- DAPT, N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester
- DTT, dithiothreitol
- Dimerization
- ECL, enzymatic chemi-luminescence
- ECLIA, electro-chemiluminescence immuno-assay
- FBS, fetal bovine serum
- FRET, fluorescence resonance energy transfer
- GXXXG motifs
- KPI, Kunitz-type protease inhibitor
- NSAIDs, nonsteroidal anti-inflammatory drugs
- PBS, phosphate buffered saline
- PS1/PS2, presenilin1/presenilin2
- RLU, relative light unit
- SP, signal peptide
- Split luciferase
- TM, transmembrane
- YFP, yellow fluorescent protein
- sAPPα, soluble APPα
- sAPPβ, soluble APPβ
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Affiliation(s)
- Marie Decock
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Laetitia El Haylani
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Serena Stanga
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Ilse Dewachter
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Jean-Noël Octave
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Steven O Smith
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Stefan N Constantinescu
- de Duve Institute and Ludwig Institute for Cancer Research, Université catholique de Louvain, Brussels 1200, Belgium
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55
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Ratnayaka JA, Serpell LC, Lotery AJ. Dementia of the eye: the role of amyloid beta in retinal degeneration. Eye (Lond) 2015; 29:1013-26. [PMID: 26088679 PMCID: PMC4541342 DOI: 10.1038/eye.2015.100] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/23/2015] [Indexed: 11/09/2022] Open
Abstract
Age-related macular degeneration (AMD) is one of the most common causes of irreversible blindness affecting nearly 50 million individuals globally. The disease is characterised by progressive loss of central vision, which has significant implications for quality of life concerns in an increasingly ageing population. AMD pathology manifests in the macula, a specialised region of the retina, which is responsible for central vision and perception of fine details. The underlying pathology of this complex degenerative disease is incompletely understood but includes both genetic as well as epigenetic risk factors. The recent discovery that amyloid beta (Aβ), a highly toxic and aggregate-prone family of peptides, is elevated in the ageing retina and is associated with AMD has opened up new perspectives on the aetiology of this debilitating blinding disease. Multiple studies now link Aβ with key stages of AMD progression, which is both exciting and potentially insightful, as this identifies a well-established toxic agent that aggressively targets cells in degenerative brains. Here, we review the most recent findings supporting the hypothesis that Aβ may be a key factor in AMD pathology. We describe how multiple Aβ reservoirs, now reported in the ageing eye, may target the cellular physiology of the retina as well as associated layers, and propose a mechanistic pathway of Aβ-mediated degenerative change leading to AMD.
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Affiliation(s)
- J A Ratnayaka
- Clinical and Experimental Science, Faculty of Medicine, University of Southampton, Southampton, UK
| | - L C Serpell
- School of Life Sciences (Biochemistry, Dementia Research Group), University of Sussex, Brighton, UK
| | - A J Lotery
- Clinical and Experimental Science, Faculty of Medicine, University of Southampton, Southampton, UK
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56
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Modeling the complex pathology of Alzheimer's disease in Drosophila. Exp Neurol 2015; 274:58-71. [PMID: 26024860 DOI: 10.1016/j.expneurol.2015.05.013] [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: 01/06/2015] [Revised: 05/13/2015] [Accepted: 05/17/2015] [Indexed: 12/18/2022]
Abstract
Alzheimer's disease (AD) is the leading cause of dementia and the most common neurodegenerative disorder. AD is mostly a sporadic disorder and its main risk factor is age, but mutations in three genes that promote the accumulation of the amyloid-β (Aβ42) peptide revealed the critical role of amyloid precursor protein (APP) processing in AD. Neurofibrillary tangles enriched in tau are the other pathological hallmark of AD, but the lack of causative tau mutations still puzzles researchers. Here, we describe the contribution of a powerful invertebrate model, the fruit fly Drosophila melanogaster, to uncover the function and pathogenesis of human APP, Aβ42, and tau. APP and tau participate in many complex cellular processes, although their main function is microtubule stabilization and the to-and-fro transport of axonal vesicles. Additionally, expression of secreted Aβ42 induces prominent neuronal death in Drosophila, a critical feature of AD, making this model a popular choice for identifying intrinsic and extrinsic factors mediating Aβ42 neurotoxicity. Overall, Drosophila has made significant contributions to better understand the complex pathology of AD, although additional insight can be expected from combining multiple transgenes, performing genome-wide loss-of-function screens, and testing anti-tau therapies alone or in combination with Aβ42.
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57
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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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58
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Vnencak M, Paul MH, Hick M, Schwarzacher SW, Del Turco D, Müller UC, Deller T, Jedlicka P. Deletion of the amyloid precursor-like protein 1 (APLP1) enhances excitatory synaptic transmission, reduces network inhibition but does not impair synaptic plasticity in the mouse dentate gyrus. J Comp Neurol 2015; 523:1717-29. [PMID: 25728909 DOI: 10.1002/cne.23766] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/21/2015] [Accepted: 02/23/2015] [Indexed: 01/02/2023]
Abstract
Amyloid precursor-like protein 1 (APLP1) is a transmembrane synaptic protein belonging to the amyloid precursor protein (APP) gene family. Although the role of this gene family-in particular of APP-has been intensely studied in the context of Alzheimer's disease, the physiological roles of its family members remain poorly understood. In particular, the function of APLP1, which is predominantly expressed in the nervous system, has remained enigmatic. Since APP has been implicated in synaptic plasticity, we wondered whether APLP1 could play a similar role. First, using in situ hybridization and laser microdissection combined with reverse transcription-quantitative polymerase chain reaction (PCR) we observed that Aplp1 mRNA is highly expressed in dentate granule cells. Having this examined, we studied synaptic plasticity at the perforant path-granule cell synapses in the dentate gyrus of APLP1-deficient mice in vivo. Analysis of field excitatory postsynaptic potentials evoked by stimulation of perforant path fibers revealed increased excitatory transmission in APLP1-deficient mice. Moreover, we observed decreased paired-pulse inhibition of population spikes indicating a decrease in network inhibition upon deletion of APLP1. In contrast, short-term presynaptic plasticity (STP) as well as long-term synaptic plasticity (LTP) was unchanged in the absence of APLP1. Based on these results we conclude that APLP1 deficiency on its own does not lead to defects in synaptic plasticity, but affects synaptic transmission and network inhibition in the dentate gyrus.
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Affiliation(s)
- Matej Vnencak
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Mandy H Paul
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Meike Hick
- Department of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Stephan W Schwarzacher
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Domenico Del Turco
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Ulrike C Müller
- Department of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
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59
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Cousins SL, Dai W, Stephenson FA. APLP1 and APLP2, members of the APP family of proteins, behave similarly to APP in that they associate with NMDA receptors and enhance NMDA receptor surface expression. J Neurochem 2015; 133:879-85. [PMID: 25683482 DOI: 10.1111/jnc.13063] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 02/02/2015] [Accepted: 02/06/2015] [Indexed: 11/30/2022]
Abstract
The function of amyloid precursor protein (APP) is unknown, although the discovery that it contributes to the regulation of surface expression of N-methyl-D-aspartate (NMDA) receptors has afforded new insights into its functional significance. Since APP is a member of a gene family that contains two other members, amyloid precursor-like proteins 1 and 2 (APLP1 and APLP2), it is important to determine if the related APP proteins possess the same properties as APP with respect to their interactions with NMDA receptors. Following expression in mammalian cells, both APLP1 and APLP2 behaved similarly to APP in that they both co-immunoprecipitated with the two major NMDA receptor subtypes, GluN1/GluN2A and GluN1/GluN2B, via interaction with the obligatory GluN1 subunit. Immunoprecipitations from detergent extracts of adult mammalian brain showed co-immunoprecipitation of APLP1 and APLP2 with GluN2A- and GluN2B-containing NMDA receptors. Furthermore, similarly to APP, APLP1 and APLP2 both enhanced GluN1/GluN2A and GluN1/GluN2B cell surface expression. Thus, all the three members of the APP gene family behave similarly in that they each contribute to the regulation of cell surface NMDA receptor homoeostasis. Amyloid precursor protein (APP) has been shown to associate with N-methyl-d-aspartate (NMDA) receptors and to enhance their cell surface expression. Here, we show that the other members of the APP family, APLP1 and APLP2, behave similarly to APP in that they both associate with assembled NMDA receptors in the endoplasmic reticulum via their interaction with the NMDA receptor subunit, GluN1 and, they enhance receptor cell surface expression. Alternative scenarios are depicted since it is to be determined if respective associations are direct.
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Affiliation(s)
| | - Wei Dai
- University College London School of Pharmacy, London, UK
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60
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Cheng F, Cappai R, Lidfeldt J, Belting M, Fransson LÅ, Mani K. Amyloid precursor protein (APP)/APP-like protein 2 (APLP2) expression is required to initiate endosome-nucleus-autophagosome trafficking of glypican-1-derived heparan sulfate. J Biol Chem 2015; 289:20871-8. [PMID: 24898256 DOI: 10.1074/jbc.m114.552810] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Anhydromannose (anMan)-containing heparan sulfate (HS) derived from the proteoglycan glypican-1 is generated in endosomes by an endogenously or ascorbate-induced S-nitrosothiolcatalyzed reaction. Processing of the amyloid precursor protein (APP) and APP-like protein 2 (APLP2) by β- and γ-secretases into amyloid β(A) and Aβ-like peptides also takes place in these compartments. Moreover, anMan-containing HS suppresses the formation of toxic Aβ assemblies in vitro. We showed by using deconvolution immunofluorescence microscopy with an anMan-specific monoclonal antibody as well as (35)S labeling experiments that expression of APP/APLP2 is required for ascorbate-induced transport of HS from endosomes to the nucleus. Nuclear translocation was observed in wild-type mouse embryonic fibroblasts (WT MEFs), Tg2576 MEFs, and N2a neuroblastoma cells but not in APP(-/-) and APLP2(-/-) MEFs. Transfection of APP(-/-) cells with a vector encoding APP restored nuclear import of anMan-containing HS. In WT MEFs and N2a neuroblastoma cells exposed to β- or γ-secretase inhibitors, nuclear translocation was greatly impeded, suggesting involvement of APP/APLP2 degradation products. In Tg2576 MEFs, the β-inhibitor blocked transport, but the γ-inhibitor did not. During chase in ascorbate- free medium, anMan-containing HS disappeared from the nuclei of WT MEFs. Confocal immunofluorescence microscopy showed that they appeared in acidic, LC3-positive vesicles in keeping with an autophagosomal location. There was increased accumulation of anMan-containing HS in nuclei and cytosolic vesicles upon treatment with chloroquine, indicating that HS was degraded in lysosomes. Manipulations of APP expression and processing may have deleterious effects upon HS function in the nucleus.
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61
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Abstract
The increasing prevalence of Alzheimer's disease (AD) and a lack of effective prevention or disease-modifying therapies are global challenges with devastating personal, social and economic consequences. The amyloid β (Aβ) hypothesis posits that cerebral β-amyloidosis is a critical early event in AD pathogenesis. However, failed clinical trials of Aβ-centric drug candidates have called this hypothesis into question. Whereas we acknowledge that the Aβ hypothesis is far from disproven, we here re-visit the links between Aβ, tau and neurodegeneration. We review the genetics, epidemiology and pathology of sporadic AD and give an updated account of what is currently known about the molecular pathogenesis of the disease.
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Affiliation(s)
- Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, Clinical Neurochemistry Laboratory, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, S-431 80 Mölndal, Sweden
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62
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Maarouf CL, Kokjohn TA, Walker DG, Whiteside CM, Kalback WM, Whetzel A, Sue LI, Serrano G, Jacobson SA, Sabbagh MN, Reiman EM, Beach TG, Roher AE. Biochemical assessment of precuneus and posterior cingulate gyrus in the context of brain aging and Alzheimer's disease. PLoS One 2014; 9:e105784. [PMID: 25166759 PMCID: PMC4148328 DOI: 10.1371/journal.pone.0105784] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/24/2014] [Indexed: 12/12/2022] Open
Abstract
Defining the biochemical alterations that occur in the brain during “normal” aging is an important part of understanding the pathophysiology of neurodegenerative diseases and of distinguishing pathological conditions from aging-associated changes. Three groups were selected based on age and on having no evidence of neurological or significant neurodegenerative disease: 1) young adult individuals, average age 26 years (n = 9); 2) middle-aged subjects, average age 59 years (n = 5); 3) oldest-old individuals, average age 93 years (n = 6). Using ELISA and Western blotting methods, we quantified and compared the levels of several key molecules associated with neurodegenerative disease in the precuneus and posterior cingulate gyrus, two brain regions known to exhibit early imaging alterations during the course of Alzheimer’s disease. Our experiments revealed that the bioindicators of emerging brain pathology remained steady or decreased with advancing age. One exception was S100B, which significantly increased with age. Along the process of aging, neurofibrillary tangle deposition increased, even in the absence of amyloid deposition, suggesting the presence of amyloid plaques is not obligatory for their development and that limited tangle density is a part of normal aging. Our study complements a previous assessment of neuropathology in oldest-old subjects, and within the limitations of the small number of individuals involved in the present investigation, it adds valuable information to the molecular and structural heterogeneity observed along the course of aging and dementia. This work underscores the need to examine through direct observation how the processes of amyloid deposition unfold or change prior to the earliest phases of dementia emergence.
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Affiliation(s)
- Chera L. Maarouf
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Tyler A. Kokjohn
- Department of Microbiology, Midwestern University, Glendale, Arizona, United States of America
| | - Douglas G. Walker
- Laboratory of Neuroinflammation, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Charisse M. Whiteside
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Walter M. Kalback
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Alexis Whetzel
- Laboratory of Neuroinflammation, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Lucia I. Sue
- Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Geidy Serrano
- Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Sandra A. Jacobson
- Cleo Roberts Center for Clinical Research, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Marwan N. Sabbagh
- Cleo Roberts Center for Clinical Research, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Eric M. Reiman
- Banner Alzheimer’s Institute, Phoenix, Arizona, United States of America
| | - Thomas G. Beach
- Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Alex E. Roher
- The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
- * E-mail:
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63
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Moore DB, Gillentine MA, Botezatu NM, Wilson KA, Benson AE, Langeland JA. Asynchronous evolutionary origins of Aβ and BACE1. Mol Biol Evol 2013; 31:696-702. [PMID: 24361992 DOI: 10.1093/molbev/mst262] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Neurodegenerative plaques characteristic of Alzheimer's disease (AD) are composed of amyloid beta (Aβ) peptide, which is proteolyzed from amyloid precursor protein (APP) by β-secretase (beta-site APP cleaving enzyme [BACE1]) and γ-secretase. Although γ-secretase has essential functions across metazoans, no essential roles have been identified for BACE1 or Aβ. Because their only known function results in a disease phenotype, we sought to understand these components from an evolutionary perspective. We show that APP-like proteins are found throughout most animal taxa, but sequences homologous to Aβ are not found outside gnathostomes and the β cut site is only conserved within sarcopterygians. BACE1 enzymes, however, extend through basal chordates and as far as cnidaria. We then sought to determine whether BACE1 from a species that never evolved Aβ could proteolyze APP substrates that include Aβ. We demonstrate that BACE1 from a basal chordate is a functional ortholog that can liberate Aβ from full-length human APP, indicating BACE1 activity evolved at least 360 My before Aβ.
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