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Dunot J, Ribera A, Pousinha PA, Marie H. Spatiotemporal insights of APP function. Curr Opin Neurobiol 2023; 82:102754. [PMID: 37542943 DOI: 10.1016/j.conb.2023.102754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/29/2023] [Accepted: 07/07/2023] [Indexed: 08/07/2023]
Abstract
The amyloid-β precursor protein (APP) is a ubiquitous protein with a strong genetic link to Alzheimer's disease. Although the protein was identified more than forty years ago, its physiological function is still unclear. In recent years, advances in technology have allowed researchers to tackle APP functions in greater depth. In this review, we discuss the latest research pertaining to APP functions from development to aging. We also address the different roles that APP could play in specific types of cells of the central and peripheral nervous system and in other organs of the body. We argue that, until we fully identify the functions of APP in space and time, we will be missing important pieces of the puzzle to solve its pathological implication in Alzheimer's disease and beyond.
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Affiliation(s)
- Jade Dunot
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, 06560, Valbonne, France. https://twitter.com/DunotJade
| | - Aurore Ribera
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, 06560, Valbonne, France. https://twitter.com/aurore_et_al_
| | - Paula A Pousinha
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, 06560, Valbonne, France.
| | - Hélène Marie
- Université Côte d'Azur, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, 06560, Valbonne, France.
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2
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Rudajev V, Novotny J. Cholesterol-dependent amyloid β production: space for multifarious interactions between amyloid precursor protein, secretases, and cholesterol. Cell Biosci 2023; 13:171. [PMID: 37705117 PMCID: PMC10500844 DOI: 10.1186/s13578-023-01127-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 09/05/2023] [Indexed: 09/15/2023] Open
Abstract
Amyloid β is considered a key player in the development and progression of Alzheimer's disease (AD). Many studies investigating the effect of statins on lowering cholesterol suggest that there may be a link between cholesterol levels and AD pathology. Since cholesterol is one of the most abundant lipid molecules, especially in brain tissue, it affects most membrane-related processes, including the formation of the most dangerous form of amyloid β, Aβ42. The entire Aβ production system, which includes the amyloid precursor protein (APP), β-secretase, and the complex of γ-secretase, is highly dependent on membrane cholesterol content. Moreover, cholesterol can affect amyloidogenesis in many ways. Cholesterol influences the stability and activity of secretases, but also dictates their partitioning into specific cellular compartments and cholesterol-enriched lipid rafts, where the amyloidogenic machinery is predominantly localized. The most complicated relationships have been found in the interaction between cholesterol and APP, where cholesterol affects not only APP localization but also the precise character of APP dimerization and APP processing by γ-secretase, which is important for the production of Aβ of different lengths. In this review, we describe the intricate web of interdependence between cellular cholesterol levels, cholesterol membrane distribution, and cholesterol-dependent production of Aβ, the major player in AD.
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Affiliation(s)
- Vladimir Rudajev
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jiri Novotny
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
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3
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Papadopoulos N, Suelves N, Perrin F, Vadukul DM, Vrancx C, Constantinescu SN, Kienlen-Campard P. Structural Determinant of β-Amyloid Formation: From Transmembrane Protein Dimerization to β-Amyloid Aggregates. Biomedicines 2022; 10:2753. [PMID: 36359274 PMCID: PMC9687742 DOI: 10.3390/biomedicines10112753] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/18/2022] [Accepted: 10/21/2022] [Indexed: 10/03/2023] Open
Abstract
Most neurodegenerative diseases have the characteristics of protein folding disorders, i.e., they cause lesions to appear in vulnerable regions of the nervous system, corresponding to protein aggregates that progressively spread through the neuronal network as the symptoms progress. Alzheimer's disease is one of these diseases. It is characterized by two types of lesions: neurofibrillary tangles (NFTs) composed of tau proteins and senile plaques, formed essentially of amyloid peptides (Aβ). A combination of factors ranging from genetic mutations to age-related changes in the cellular context converge in this disease to accelerate Aβ deposition. Over the last two decades, numerous studies have attempted to elucidate how structural determinants of its precursor (APP) modify Aβ production, and to understand the processes leading to the formation of different Aβ aggregates, e.g., fibrils and oligomers. The synthesis proposed in this review indicates that the same motifs can control APP function and Aβ production essentially by regulating membrane protein dimerization, and subsequently Aβ aggregation processes. The distinct properties of these motifs and the cellular context regulate the APP conformation to trigger the transition to the amyloid pathology. This concept is critical to better decipher the patterns switching APP protein conformation from physiological to pathological and improve our understanding of the mechanisms underpinning the formation of amyloid fibrils that devastate neuronal functions.
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Affiliation(s)
- Nicolas Papadopoulos
- SIGN Unit, de Duve Institute, UCLouvain, 1200 Brussels, Belgium
- Ludwig Institute for Cancer Research Brussels, 1348 Brussels, Belgium
| | - Nuria Suelves
- Aging and Dementia Research Group, Cellular and Molecular (CEMO) Division, Institute of Neuroscience, UCLouvain, 1200 Brussels, Belgium
| | - Florian Perrin
- Memory Disorders Unit, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Devkee M. Vadukul
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London SW7 2BX, UK
| | - Céline Vrancx
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, KU Leuven, 3000 Leuven, Belgium
- Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium
| | - Stefan N. Constantinescu
- SIGN Unit, de Duve Institute, UCLouvain, 1200 Brussels, Belgium
- Ludwig Institute for Cancer Research Brussels, 1348 Brussels, Belgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO), 1300 Wavre, Belgium
- Nuffield Department of Medicine, Ludwig Institute for Cancer Research, Oxford University, Oxford OX1 2JD, UK
| | - Pascal Kienlen-Campard
- Aging and Dementia Research Group, Cellular and Molecular (CEMO) Division, Institute of Neuroscience, UCLouvain, 1200 Brussels, Belgium
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4
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Onodera W, Asahi T, Sawamura N. Rapid evolution of mammalian APLP1 as a synaptic adhesion molecule. Sci Rep 2021; 11:11305. [PMID: 34050225 PMCID: PMC8163877 DOI: 10.1038/s41598-021-90737-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/17/2021] [Indexed: 01/10/2023] Open
Abstract
Amyloid precursor protein (APP) family members are involved in essential neuronal development including neurite outgrowth, neuronal migration and maturation of synapse and neuromuscular junction. Among the APP gene family members, amyloid precursor-like protein 1 (APLP1) is selectively expressed in neurons and has specialized functions during synaptogenesis. Although a potential role for APLP1 in neuronal evolution has been indicated, its precise evolutionary and functional contributions are unknown. This study shows the molecular evolution of the vertebrate APP family based on phylogenetic analysis, while contrasting the evolutionary differences within the APP family. Phylogenetic analysis showed 15 times higher substitution rate that is driven by positive selection at the stem branch of the mammalian APLP1, resulting in dissimilar protein sequences compared to APP/APLP2. Docking simulation identified one positively selected site in APLP1 that alters the heparin-binding site, which could affect its function, and dimerization rate. Furthermore, the evolutionary rate covariation between the mammalian APP family and synaptic adhesion molecules (SAMs) was confirmed, indicating that only APLP1 has evolved to gain synaptic adhesion property. Overall, our results suggest that the enhanced synaptogenesis property of APLP1 as one of the SAMs may have played a role in mammalian brain evolution.
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Affiliation(s)
- Wataru Onodera
- Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo, 162-8480, Japan
| | - Toru Asahi
- Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo, 162-8480, Japan.,Research Organization for Nano & Life Innovation, Waseda University, #03C309, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo, 162-8480, Japan
| | - Naoya Sawamura
- Research Organization for Nano & Life Innovation, Waseda University, #03C309, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo, 162-8480, Japan. .,Green Computing Systems Research Organization, Waseda University, Shinjuku, Japan.
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5
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Lanchec E, Désilets A, Béliveau F, Fontaine-Carbonneau C, Laniel A, Leduc R, Lavoie C. Matriptase processing of APLP1 ectodomain alters its homodimerization. Sci Rep 2020; 10:10091. [PMID: 32572095 PMCID: PMC7308337 DOI: 10.1038/s41598-020-67005-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 05/29/2020] [Indexed: 11/09/2022] Open
Abstract
The amyloid beta peptide (Aβ) is derived from the amyloid precursor protein (APP) by secretase processing. APP is also cleaved by numerous other proteases, such as the type II transmembrane serine protease matriptase, with consequences on the production of Aβ. Because the APP homolog protein amyloid-like protein 1 (APLP1) shares similarities with APP, we sought to determine if matriptase also plays a role in its processing. Here, we demonstrate that matriptase directly interacts with APLP1 and that APLP1 is cleaved in cellulo by matriptase in its E1 ectodomains at arginine 124. Replacing Arg124 with Ala abolished APLP1 processing by matriptase. Using a bioluminescence resonance energy transfer (BRET) assay we found that matriptase reduces APLP1 homodimeric interactions. This study identifies matriptase as the first protease cleaving APLP1 in its dimerization domain, potentially altering the multiple functions associated with dimer formation.
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Affiliation(s)
- Erwan Lanchec
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H5N4, Canada
| | - Antoine Désilets
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H5N4, Canada
| | - François Béliveau
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H5N4, Canada
| | - Cloé Fontaine-Carbonneau
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H5N4, Canada
| | - Andréanne Laniel
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H5N4, Canada
| | - Richard Leduc
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H5N4, Canada.
| | - Christine Lavoie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, J1H5N4, Canada.
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6
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Scharfenberg F, Armbrust F, Marengo L, Pietrzik C, Becker-Pauly C. Regulation of the alternative β-secretase meprin β by ADAM-mediated shedding. Cell Mol Life Sci 2019; 76:3193-3206. [PMID: 31201463 PMCID: PMC11105663 DOI: 10.1007/s00018-019-03179-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 05/23/2019] [Accepted: 05/29/2019] [Indexed: 12/12/2022]
Abstract
Alzheimer's Disease (AD) is the sixth-leading cause of death in industrialized countries. Neurotoxic amyloid-β (Aβ) plaques are one of the pathological hallmarks in AD patient brains. Aβ accumulates in the brain upon sequential, proteolytic processing of the amyloid precursor protein (APP) by β- and γ-secretases. However, so far disease-modifying drugs targeting β- and γ-secretase pathways seeking a decrease in the production of toxic Aβ peptides have failed in clinics. It has been demonstrated that the metalloproteinase meprin β acts as an alternative β-secretase, capable of generating truncated Aβ2-x peptides that have been described to be increased in AD patients. This indicates an important β-site cleaving enzyme 1 (BACE-1)-independent contribution of the metalloprotease meprin β within the amyloidogenic pathway and may lead to novel drug targeting avenues. However, meprin β itself is embedded in a complex regulatory network. Remarkably, the anti-amyloidogenic α-secretase a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) is a direct competitor for APP at the cell surface, but also a sheddase of inactive pro-meprin β. Overall, we highlight the current cellular, molecular and structural understanding of meprin β as alternative β-secretase within the complex protease web, regulating APP processing in health and disease.
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Affiliation(s)
- Franka Scharfenberg
- Unit for Degradomics of the Protease Web, Biochemical Institute, University of Kiel, Kiel, Germany
| | - Fred Armbrust
- Unit for Degradomics of the Protease Web, Biochemical Institute, University of Kiel, Kiel, Germany
| | - Liana Marengo
- Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Claus Pietrzik
- Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.
| | - Christoph Becker-Pauly
- Unit for Degradomics of the Protease Web, Biochemical Institute, University of Kiel, Kiel, Germany.
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7
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Dlouhy AC, Bailey DK, Steimle BL, Parker HV, Kosman DJ. Fluorescence resonance energy transfer links membrane ferroportin, hephaestin but not ferroportin, amyloid precursor protein complex with iron efflux. J Biol Chem 2019; 294:4202-4214. [PMID: 30647129 DOI: 10.1074/jbc.ra118.005142] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 01/08/2019] [Indexed: 11/06/2022] Open
Abstract
Iron efflux from mammalian cells is supported by the synergistic actions of the ferrous iron efflux transporter, ferroportin (Fpn) and a multicopper ferroxidase, that is, hephaestin (Heph), ceruloplasmin (Cp) or both. The two proteins stabilize Fpn in the plasma membrane and catalyze extracellular Fe3+ release. The membrane stabilization of Fpn is also stimulated by its interaction with a 22-amino acid synthetic peptide based on a short sequence in the extracellular E2 domain of the amyloid precursor protein (APP). However, whether APP family members interact with Fpn in vivo is unclear. Here, using cyan fluorescent protein (CFP)-tagged Fpn in conjunction with yellow fluorescent protein (YFP) fusions of Heph and APP family members APP, APLP1, and APLP2 in HEK293T cells we used fluorescence and surface biotinylation to quantify Fpn membrane occupancy and also measured 59Fe efflux. We demonstrate that Fpn and Heph co-localize, and FRET analysis indicated that the two proteins form an iron-efflux complex. In contrast, none of the full-length, cellular APP proteins exhibited Fpn co-localization or FRET. Moreover, iron supplementation increased surface expression of the iron-efflux complex, and copper depletion knocked down Heph activity and decreased Fpn membrane localization. Whereas cellular APP species had no effects on Fpn and Heph localization, addition of soluble E2 elements derived from APP and APLP2, but not APLP1, increased Fpn membrane occupancy. We conclude that a ferroportin-targeting sequence, (K/R)EWEE, present in APP and APLP2, but not APLP1, helps modulate Fpn-dependent iron efflux in the presence of an active multicopper ferroxidase.
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Affiliation(s)
- Adrienne C Dlouhy
- From the Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
| | - Danielle K Bailey
- From the Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
| | - Brittany L Steimle
- From the Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
| | - Haley V Parker
- From the Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
| | - Daniel J Kosman
- From the Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203
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8
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Young TR, Wedd AG, Xiao Z. Evaluation of Cu(i) binding to the E2 domain of the amyloid precursor protein - a lesson in quantification of metal binding to proteins via ligand competition. Metallomics 2019; 10:108-119. [PMID: 29215101 DOI: 10.1039/c7mt00291b] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The extracellular domain E2 of the amyloid precursor protein (APP) features a His-rich metal-binding site (denoted as the M1 site). In conjunction with surrounding basic residues, the site participates in interactions with components of the extracellular matrix including heparins, a class of negatively charged polysaccharide molecules of varying length. This work studied the chemistry of Cu(i) binding to APP E2 with the probe ligands Bcs, Bca, Fz and Fs. APP E2 forms a stable Cu(i)-mediated ternary complex with each of these anionic ligands. The complex with Bca was selected for isolation and characterization and was demonstrated, by native ESI-MS analysis, to have the stoichiometry E2 : Cu(i) : Bca = 1 : 1 : 1. Formation of these ternary complexes is specific for the APP E2 domain and requires Cu(i) coordination to the M1 site. Mutation of the M1 site was consistent with the His ligands being part of the E2 ligand set. It is likely that interactions between the negatively charged probe ligands and a positively charged patch on the surface of APP E2 are one aspect of the generation of the stable ternary complexes. Their formation prevented meaningful quantification of the affinity of Cu(i) binding to the M1 site with these probe ligands. However, the ternary complexes are disrupted by heparin, allowing reliable determination of a picomolar Cu(i) affinity for the E2/heparin complex with the Fz or Bca probe ligands. This is the first documented example of the formation of stable ternary complexes between a Cu(i) binding protein and a probe ligand. The ready disruption of the complexes by heparin identified clear 'tell-tale' signs for diagnosis of ternary complex formation and allowed a systematic review of conditions and criteria for reliable determination of affinities for metal binding via ligand competition. This study also provides new insights into a potential correlation of APP functions regulated by copper binding and heparin interaction.
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Affiliation(s)
- Tessa R Young
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
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9
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Young TR, Pukala TL, Cappai R, Wedd AG, Xiao Z. The Human Amyloid Precursor Protein Binds Copper Ions Dominated by a Picomolar-Affinity Site in the Helix-Rich E2 Domain. Biochemistry 2018; 57:4165-4176. [DOI: 10.1021/acs.biochem.8b00572] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Tessa R. Young
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Tara L. Pukala
- Discipline of Chemistry, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Roberto Cappai
- Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Anthony G. Wedd
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Zhiguang Xiao
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3052, Australia
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10
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Montagna E, Dorostkar MM, Herms J. The Role of APP in Structural Spine Plasticity. Front Mol Neurosci 2017; 10:136. [PMID: 28539872 PMCID: PMC5423954 DOI: 10.3389/fnmol.2017.00136] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/21/2017] [Indexed: 11/15/2022] Open
Abstract
Amyloid precursor protein (APP) is a transmembrane protein highly expressed in neurons. The full-length protein has cell-adhesion and receptor-like properties, which play roles in synapse formation and stability. Furthermore, APP can be cleaved by several proteases into numerous fragments, many of which affect synaptic function and stability. This review article focuses on the mechanisms of APP in structural spine plasticity, which encompasses the morphological alterations at excitatory synapses. These occur as changes in the number and morphology of dendritic spines, which correspond to the postsynaptic compartment of excitatory synapses. Both overexpression and knockout (KO) of APP lead to impaired synaptic plasticity. Recent data also suggest a role of APP in the regulation of astrocytic D-serine homeostasis, which in turn regulates synaptic plasticity.
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Affiliation(s)
- Elena Montagna
- Department for Translational Brain Research, German Center for Neurodegenerative Diseases (DZNE), Ludwig-Maximilian-University MunichMunich, Germany
| | - Mario M Dorostkar
- Center for Neuropathology and Prion Research, Ludwig-Maximilian-University MunichMunich, Germany
| | - Jochen Herms
- Department for Translational Brain Research, German Center for Neurodegenerative Diseases (DZNE), Ludwig-Maximilian-University MunichMunich, Germany.,Center for Neuropathology and Prion Research, Ludwig-Maximilian-University MunichMunich, Germany.,Munich Cluster of Systems Neurology (SyNergy), Ludwig-Maximilian-University MunichMunich, Germany
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11
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Wang B, Li H, Mutlu SA, Bowser DA, Moore MJ, Wang MC, Zheng H. The Amyloid Precursor Protein Is a Conserved Receptor for Slit to Mediate Axon Guidance. eNeuro 2017; 4:ENEURO.0185-17.2017. [PMID: 28785723 PMCID: PMC5534435 DOI: 10.1523/eneuro.0185-17.2017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 05/29/2017] [Indexed: 02/03/2023] Open
Abstract
The amyloid precursor protein (APP) is a receptor-like membrane protein. Although APP processing and β-amyloid production play a central role in Alzheimer's disease (AD) pathogenesis, the physiological function of APP remains elusive. Here, we identify APP as a novel receptor for Slit that mediates axon guidance and neural circuit formation. APP deficiency abolishes the Slit repulsive effect in a 3D olfactory explant culture, consistent with its callosal projection deficit in vivo and reminiscent of Slit loss. Inactivation of APP ortholog APL-1 in Caenorhabditis elegans results in pioneer axon mistargeting and genetic analysis places APL-1 in the SLT-1 (Slit)/SAX-3 (Robo) repulsive pathway. Slit binds to APP through the E1 domain, which triggers APP ectodomain shedding and recruitment of the intracellular FE65 and Pak1 complex and associated Rac1 GTPase activation. Our study establishes APP as a novel receptor for Slit ligand mediating axon guidance and neural circuit formation.
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Affiliation(s)
- Baiping Wang
- Huffington Center on Aging and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
| | - Hongmei Li
- Huffington Center on Aging and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
| | - Sena A. Mutlu
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030
| | - Devon A. Bowser
- Interdisciplinary Bioinnovation PhD Program, Tulane University, New Orleans, LA 70118
| | - Michael J. Moore
- Department of Biomedical Engineering, Tulane University, New Orleans, LA 70118
| | - Meng C. Wang
- Huffington Center on Aging and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
| | - Hui Zheng
- Huffington Center on Aging and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030
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12
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Bhattacharyya R, Fenn RH, Barren C, Tanzi RE, Kovacs DM. Palmitoylated APP Forms Dimers, Cleaved by BACE1. PLoS One 2016; 11:e0166400. [PMID: 27875558 PMCID: PMC5119739 DOI: 10.1371/journal.pone.0166400] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 10/30/2016] [Indexed: 11/26/2022] Open
Abstract
A major rate-limiting step for Aβ generation and deposition in Alzheimer's disease brains is BACE1-mediated cleavage (β-cleavage) of the amyloid precursor protein (APP). We previously reported that APP undergoes palmitoylation at two cysteine residues (Cys186 and Cys187) in the E1-ectodomain. 8-10% of total APP is palmitoylated in vitro and in vivo. Palmitoylated APP (palAPP) shows greater preference for β-cleavage than total APP in detergent resistant lipid rafts. Protein palmitoylation is known to promote protein dimerization. Since dimerization of APP at its E1-ectodomain results in elevated BACE1-mediated cleavage of APP, we have now investigated whether palmitoylation of APP affects its dimerization and whether this leads to elevated β-cleavage of the protein. Here we report that over 90% of palAPP is dimerized while only ~20% of total APP forms dimers. PalAPP-dimers are predominantly cis-oriented while total APP dimerizes in both cis- and trans-orientation. PalAPP forms dimers 4.5-times more efficiently than total APP. Overexpression of the palmitoylating enzymes DHHC7 and DHHC21 that increase palAPP levels and Aβ release, also increased APP dimerization in cells. Conversely, inhibition of APP palmitoylation by pharmacological inhibitors reduced APP-dimerization in coimmunoprecipitation and FLIM/FRET assays. Finally, in vitro BACE1-activity assays demonstrate that palmitoylation-dependent dimerization of APP promotes β-cleavage of APP in lipid-rich detergent resistant cell membranes (DRMs), when compared to total APP. Most importantly, generation of sAPPβ-sAPPβ dimers is dependent on APP-palmitoylation while total sAPPβ generation is not. Since BACE1 shows preference for palAPP dimers over total APP, palAPP dimers may serve as novel targets for effective β-cleavage inhibitors of APP as opposed to BACE1 inhibitors.
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Affiliation(s)
- Raja Bhattacharyya
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Diseases (MIND), Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States of America
| | - Rebecca H. Fenn
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Diseases (MIND), Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States of America
| | - Cory Barren
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Diseases (MIND), Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States of America
| | - Rudolph E. Tanzi
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Diseases (MIND), Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States of America
| | - Dora M. Kovacs
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Diseases (MIND), Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, United States of America
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Habib A, Sawmiller D, Tan J. Restoring Soluble Amyloid Precursor Protein α Functions as a Potential Treatment for Alzheimer's Disease. J Neurosci Res 2016; 95:973-991. [PMID: 27531392 DOI: 10.1002/jnr.23823] [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: 01/19/2016] [Revised: 06/13/2016] [Accepted: 06/15/2016] [Indexed: 12/14/2022]
Abstract
Soluble amyloid precursor protein α (sAPPα), a secreted proteolytic fragment of nonamyloidogenic amyloid precursor protein (APP) processing, is known for numerous neuroprotective functions. These functions include but are not limited to proliferation, neuroprotection, synaptic plasticity, memory formation, neurogenesis, and neuritogenesis in cell culture and animal models. In addition, sAPPα influences amyloid-β (Aβ) production by direct modulation of APP β-secretase proteolysis as well as Aβ-related or unrelated tau pathology, hallmark pathologies of Alzheimer's disease (AD). Thus, the restoration of sAPPα levels and functions in the brain by increasing nonamyloidogenic APP processing and/or manipulation of its signaling could reduce AD pathology and cognitive impairment. It is likely that identification and characterization of sAPPα receptors in the brain, downstream effectors, and signaling pathways will pave the way for an attractive therapeutic target for AD prevention or intervention. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ahsan Habib
- Rashid Laboratory for Developmental Neurobiology, Silver Child Development Center, Department of Psychiatry and Behavioral Neurosciences, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Darrell Sawmiller
- Rashid Laboratory for Developmental Neurobiology, Silver Child Development Center, Department of Psychiatry and Behavioral Neurosciences, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Jun Tan
- Rashid Laboratory for Developmental Neurobiology, Silver Child Development Center, Department of Psychiatry and Behavioral Neurosciences, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
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Plummer S, Van den Heuvel C, Thornton E, Corrigan F, Cappai R. The Neuroprotective Properties of the Amyloid Precursor Protein Following Traumatic Brain Injury. Aging Dis 2016; 7:163-79. [PMID: 27114849 PMCID: PMC4809608 DOI: 10.14336/ad.2015.0907] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 09/07/2015] [Indexed: 01/16/2023] Open
Abstract
Despite the significant health and economic burden that traumatic brain injury (TBI) places on society, the development of successful therapeutic agents have to date not translated into efficacious therapies in human clinical trials. Injury to the brain is ongoing after TBI, through a complex cascade of primary and secondary injury events, providing a valuable window of opportunity to help limit and prevent some of the severe consequences with a timely treatment. Of note, it has been suggested that novel treatments for TBI should be multifactorial in nature, mimicking the body's own endogenous repair response. Whilst research has historically focused on the role of the amyloid precursor protein (APP) in the pathogenesis of Alzheimer's disease, recent advances in trauma research have demonstrated that APP offers considerable neuroprotective properties following TBI, suggesting that APP is an ideal therapeutic candidate. Its acute upregulation following TBI has been shown to serve a beneficial role following trauma and has lead to significant advances in understanding the neuroprotective and neurotrophic functions of APP and its metabolites. Research has focused predominantly on the APP derivative sAPPα, which has consistently demonstrated neuroprotective and neurotrophic functions both in vitro and in vivo following various traumatic insults. Its neuroprotective activity has been narrowed down to a 15 amino acid sequence, and this region is linked to both heparan binding and growth-factor-like properties. It has been proposed that APP binds to heparan sulfate proteoglycans to exert its neuroprotective action. APP presents us with a novel therapeutic compound that could overcome many of the challenges that have stalled development of efficacious TBI treatments previously.
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Affiliation(s)
- Stephanie Plummer
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Corinna Van den Heuvel
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Emma Thornton
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Frances Corrigan
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Roberto Cappai
- Department of Pathology, the University of Melbourne, Victoria, Australia
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15
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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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16
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The crystal structure of DR6 in complex with the amyloid precursor protein provides insight into death receptor activation. Genes Dev 2015; 29:785-90. [PMID: 25838500 PMCID: PMC4403255 DOI: 10.1101/gad.257675.114] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/09/2015] [Indexed: 11/25/2022]
Abstract
Death receptor 6 (DR6) was recently shown to bind amyloid precursor protein (APP) via the protein extracellular regions, stimulate axonal pruning, and inhibit synapse formation. Xu et al. report the crystal structure of the DR6 ectodomain in complex with the E2 domain of APP and show that it supports a model for APP-induced dimerization and activation of cell surface DR6. The amyloid precursor protein (APP) has garnered considerable attention due to its genetic links to Alzheimer's disease. Death receptor 6 (DR6) was recently shown to bind APP via the protein extracellular regions, stimulate axonal pruning, and inhibit synapse formation. Here, we report the crystal structure of the DR6 ectodomain in complex with the E2 domain of APP and show that it supports a model for APP-induced dimerization and activation of cell surface DR6.
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Dahms SO, Mayer MC, Roeser D, Multhaup G, Than ME. Interaction of the amyloid precursor protein-like protein 1 (APLP1) E2 domain with heparan sulfate involves two distinct binding modes. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:494-504. [PMID: 25760599 PMCID: PMC4356362 DOI: 10.1107/s1399004714027114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/10/2014] [Indexed: 01/09/2023]
Abstract
Beyond the pathology of Alzheimer's disease, the members of the amyloid precursor protein (APP) family are essential for neuronal development and cell homeostasis in mammals. APP and its paralogues APP-like protein 1 (APLP1) and APP-like protein 2 (APLP2) contain the highly conserved heparan sulfate (HS) binding domain E2, which effects various (patho)physiological functions. Here, two crystal structures of the E2 domain of APLP1 are presented in the apo form and in complex with a heparin dodecasaccharide at 2.5 Å resolution. The apo structure of APLP1 E2 revealed an unfolded and hence flexible N-terminal helix αA. The (APLP1 E2)2-(heparin)2 complex structure revealed two distinct binding modes, with APLP1 E2 explicitly recognizing the heparin terminus but also interacting with a continuous heparin chain. The latter only requires a certain register of the sugar moieties that fits to a positively charged surface patch and contributes to the general heparin-binding capability of APP-family proteins. Terminal binding of APLP1 E2 to heparin specifically involves a structure of the nonreducing end that is very similar to heparanase-processed HS chains. These data reveal a conserved mechanism for the binding of APP-family proteins to HS and imply a specific regulatory role of HS modifications in the biology of APP and APP-like proteins.
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Affiliation(s)
- Sven O. Dahms
- Protein Crystallography Group, Leibniz Institute for Age Research (FLI), Beutenbergstrasse 11, 07745 Jena, Germany
| | - Magnus C. Mayer
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
- Miltenyi Biotec GmbH, Robert-Koch-Strasse 1, 17166 Teterow, Germany
| | - Dirk Roeser
- Protein Crystallography Group, Leibniz Institute for Age Research (FLI), Beutenbergstrasse 11, 07745 Jena, Germany
| | - Gerd Multhaup
- Department of Pharmacology and Therapeutics, McGill University Montreal, Montreal, Quebec H3G 1Y6, Canada
| | - Manuel E. Than
- Protein Crystallography Group, Leibniz Institute for Age Research (FLI), Beutenbergstrasse 11, 07745 Jena, Germany
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Hoefgen S, Dahms SO, Oertwig K, Than ME. The amyloid precursor protein shows a pH-dependent conformational switch in its E1 domain. J Mol Biol 2014; 427:433-42. [PMID: 25528641 DOI: 10.1016/j.jmb.2014.12.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 12/09/2014] [Accepted: 12/09/2014] [Indexed: 10/24/2022]
Abstract
The amyloid precursor protein (APP) and its proteolytic cleavage product Aβ are widely believed to be central to the etiology of Alzheimer's disease (AD). APP and its family members are also essential for proper neuronal development and homeostasis. APP is located at the cell surface and within intracellular compartments, cellular regions that exhibit different pH values. The AD-associated amyloidogenic processing of APP is initiated predominantly in intracellular acidic compartments, whereas its non-amyloidogenic cleavage is initiated at the cell surface at slightly basic pH. We analyzed the influence of pH on the APP-E1 domain and found that its two constituting subdomains, GFLD and CuBD, interact with each other in a pH-dependent manner. Dynamic light scattering showed that APP-E1 represents a more open conformation at neutral pH and a more closed conformation at acidic pH. Analyzing a 1.4 Å, high-resolution X-ray structure of E1 derived from merohedrally twinned crystals resulted in the identification of individual residues that are responsible for these pH-dependent interactions. Mutational studies and dynamic light scattering measurements further proved that specific hydrogen bonds between the two carboxylates of D177 and E87, as well as between N89 and H147, are major determinants of this pH-driven conformational switch in APP-E1. These findings show how APP can adopt different conformations depending on pH and suggest that the protein fulfils different functions at distinct localizations within the cell. Additionally, our data suggest a novel strategy for treating AD based on regulating the amyloidogenic processing of APP by the specific interruption of the interaction between the APP-E1 subdomains.
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Affiliation(s)
- Sandra Hoefgen
- Protein Crystallography Group, Leibniz Institute for Age Research, Fritz Lipmann Institute (FLI), Beutenbergstrasse 11, 07745 Jena, Germany
| | - Sven O Dahms
- Protein Crystallography Group, Leibniz Institute for Age Research, Fritz Lipmann Institute (FLI), Beutenbergstrasse 11, 07745 Jena, Germany
| | - Kathrin Oertwig
- Protein Crystallography Group, Leibniz Institute for Age Research, Fritz Lipmann Institute (FLI), Beutenbergstrasse 11, 07745 Jena, Germany
| | - Manuel E Than
- Protein Crystallography Group, Leibniz Institute for Age Research, Fritz Lipmann Institute (FLI), Beutenbergstrasse 11, 07745 Jena, Germany.
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