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Nithianandam V, Bukhari H, Leventhal MJ, Battaglia RA, Dong X, Fraenkel E, Feany MB. Integrative analysis reveals a conserved role for the amyloid precursor protein in proteostasis during aging. Nat Commun 2023; 14:7034. [PMID: 37923712 PMCID: PMC10624868 DOI: 10.1038/s41467-023-42822-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 10/23/2023] [Indexed: 11/06/2023] Open
Abstract
Aβ peptides derived from the amyloid precursor protein (APP) have been strongly implicated in the pathogenesis of Alzheimer's disease. However, the normal function of APP and the importance of that role in neurodegenerative disease is less clear. We recover the Drosophila ortholog of APP, Appl, in an unbiased forward genetic screen for neurodegeneration mutants. We perform comprehensive single cell transcriptional and proteomic studies of Appl mutant flies to investigate Appl function in the aging brain. We find an unexpected role for Appl in control of multiple cellular pathways, including translation, mitochondrial function, nucleic acid and lipid metabolism, cellular signaling and proteostasis. We mechanistically define a role for Appl in regulating autophagy through TGFβ signaling and document the broader relevance of our findings using mouse genetic, human iPSC and in vivo tauopathy models. Our results demonstrate a conserved role for APP in controlling age-dependent proteostasis with plausible relevance to Alzheimer's disease.
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Affiliation(s)
- Vanitha Nithianandam
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, 20815, USA
| | - Hassan Bukhari
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, 20815, USA
| | - Matthew J Leventhal
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- MIT Ph.D. Program in Computational and Systems Biology, Cambridge, MA, USA
| | - Rachel A Battaglia
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, 20815, USA
| | - Xianjun Dong
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, 20815, USA
- Genomics and Bioinformatics Hub, Brigham and Women's Hospital, Boston, MA, USA
| | - Ernest Fraenkel
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Mel B Feany
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD, 20815, USA.
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2
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Chau DDL, Ng LLH, Zhai Y, Lau KF. Amyloid precursor protein and its interacting proteins in neurodevelopment. Biochem Soc Trans 2023; 51:1647-1659. [PMID: 37387352 PMCID: PMC10629809 DOI: 10.1042/bst20221527] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/01/2023]
Abstract
Amyloid precursor protein (APP) is a key molecule in the pathogenesis of Alzheimer's disease (AD) as the pathogenic amyloid-β peptide is derived from it. Two closely related APP family proteins (APPs) have also been identified in mammals. Current knowledge, including genetic analyses of gain- and loss-of-function mutants, highlights the importance of APPs in various physiological functions. Notably, APPs consist of multiple extracellular and intracellular protein-binding regions/domains. Protein-protein interactions are crucial for many cellular processes. In past decades, many APPs interactors have been identified which assist the revelation of the putative roles of APPs. Importantly, some of these interactors have been shown to influence several APPs-mediated neuronal processes which are found defective in AD and other neurodegenerative disorders. Studying APPs-interactor complexes would not only advance our understanding of the physiological roles of APPs but also provide further insights into the association of these processes to neurodegeneration, which may lead to the development of novel therapies. In this mini-review, we summarize the roles of APPs-interactor complexes in neurodevelopmental processes including neurogenesis, neurite outgrowth, axonal guidance and synaptogenesis.
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Affiliation(s)
- Dennis Dik-Long Chau
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Laura Lok-Haang Ng
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Yuqi Zhai
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Kwok-Fai Lau
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
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3
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Navarro-Martínez A, Vicente-García C, Carvajal JJ. NMJ-related diseases beyond the congenital myasthenic syndromes. Front Cell Dev Biol 2023; 11:1216726. [PMID: 37601107 PMCID: PMC10436495 DOI: 10.3389/fcell.2023.1216726] [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: 05/04/2023] [Accepted: 07/21/2023] [Indexed: 08/22/2023] Open
Abstract
Neuromuscular junctions (NMJs) are a special type of chemical synapse that transmits electrical stimuli from motor neurons (MNs) to their innervating skeletal muscle to induce a motor response. They are an ideal model for the study of synapses, given their manageable size and easy accessibility. Alterations in their morphology or function lead to neuromuscular disorders, such as the congenital myasthenic syndromes, which are caused by mutations in proteins located in the NMJ. In this review, we highlight novel potential candidate genes that may cause or modify NMJs-related pathologies in humans by exploring the phenotypes of hundreds of mouse models available in the literature. We also underscore the fact that NMJs may differ between species, muscles or even sexes. Hence the importance of choosing a good model organism for the study of NMJ-related diseases: only taking into account the specific features of the mammalian NMJ, experimental results would be efficiently translated to the clinic.
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Affiliation(s)
| | - Cristina Vicente-García
- Centro Andaluz de Biología del Desarrollo, CSIC-UPO-JA, Universidad Pablo de Olavide, Sevilla, Spain
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4
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Wu MY, Zou WJ, Lee D, Mei L, Xiong WC. APP in the Neuromuscular Junction for the Development of Sarcopenia and Alzheimer's Disease. Int J Mol Sci 2023; 24:ijms24097809. [PMID: 37175515 PMCID: PMC10178513 DOI: 10.3390/ijms24097809] [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: 04/05/2023] [Revised: 04/18/2023] [Accepted: 04/22/2023] [Indexed: 05/15/2023] Open
Abstract
Sarcopenia, an illness condition usually characterized by a loss of skeletal muscle mass and muscle strength or function, is often associated with neurodegenerative diseases, such as Alzheimer's disease (AD), a common type of dementia, leading to memory loss and other cognitive impairment. However, the underlying mechanisms for their associations and relationships are less well understood. The App, a Mendelian gene for early-onset AD, encodes amyloid precursor protein (APP), a transmembrane protein enriched at both the neuromuscular junction (NMJ) and synapses in the central nervous system (CNS). Here, in this review, we highlight APP and its family members' physiological functions and Swedish mutant APP (APPswe)'s pathological roles in muscles and NMJ. Understanding APP's pathophysiological functions in muscles and NMJ is likely to uncover insights not only into neuromuscular diseases but also AD. We summarize key findings from the burgeoning literature, which may open new avenues to investigate the link between muscle cells and brain cells in the development and progression of AD and sarcopenia.
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Affiliation(s)
- Min-Yi Wu
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Wen-Jun Zou
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Daehoon Lee
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
- Louis Stokes Cleveland Veterans Affairs Medical Center, Northeast Ohio VA Healthcare System, Cleveland, OH 44106, USA
| | - Lin Mei
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Wen-Cheng Xiong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
- Louis Stokes Cleveland Veterans Affairs Medical Center, Northeast Ohio VA Healthcare System, Cleveland, OH 44106, USA
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Babić Leko M, Hof PR, Šimić G. Alterations and interactions of subcortical modulatory systems in Alzheimer's disease. PROGRESS IN BRAIN RESEARCH 2021; 261:379-421. [PMID: 33785136 DOI: 10.1016/bs.pbr.2020.07.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The pathogenesis of Alzheimer's disease (AD) is not fully understood. Here we summarize current knowledge on the involvement of the serotonergic, noradrenergic, dopaminergic, cholinergic, and opioid systems in AD, emphasizing the importance of interactions between the serotonergic and the other subcortical modulatory systems during the progression of AD. In physiological conditions, all neurotransmitter systems function in concert and are interdependent at both the neuroanatomical and molecular levels. Through their early involvement in AD, cognitive and behavioral abilities that rely on their interactions also become disrupted. Considering that serotonin (5HT) regulates the release of noradrenaline (NA), dopamine (DA) and acetylcholine (ACh), any alteration in 5HT levels leads to disturbance of NA, DA, and ACh homeostasis in the brain. One of the earliest pathological changes during the prodromal phase of AD is a decrease of serotonergic transmission throughout the brain, with serotonergic receptors being also affected. Additionally, serotonergic and noradrenergic as well as serotonergic and dopaminergic nuclei are reciprocally interconnected. As the serotonergic dorsal raphe nucleus (DRN) is affected by pathological changes early in AD, and the noradrenergic locus coeruleus (LC) and dopaminergic ventral tegmental area (VTA) exhibit AD-related pathological changes, their connectivity also becomes altered in AD. Such disrupted interactions among neurotransmitter systems in AD can be used in the development of multi-target drugs. Some of the potential AD therapeutics (such as ASS234, RS67333, tropisetron) target multiple neurotransmitter systems to achieve the best possible improvement of cognitive and behavioral deficits observed in AD. Here, we review how serotonergic system interacts with other subcortical modulatory systems (noradrenergic, dopaminergic, cholinergic, and opioid systems) during AD.
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Affiliation(s)
- Mirjana Babić Leko
- Department for Neuroscience, Croatian Institute for Brain Research, University of Zagreb Medical School, Zagreb, Croatia
| | - Patrick R Hof
- Nash Family Department of Neuroscience, Friedman Brain Institute, and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Goran Šimić
- Department for Neuroscience, Croatian Institute for Brain Research, University of Zagreb Medical School, Zagreb, Croatia.
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Triaca V, Ruberti F, Canu N. NGF and the Amyloid Precursor Protein in Alzheimer's Disease: From Molecular Players to Neuronal Circuits. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1331:145-165. [PMID: 34453297 DOI: 10.1007/978-3-030-74046-7_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease (AD), one of the most common causes of dementia in elderly people, is characterized by progressive impairment in cognitive function, early degeneration of basal forebrain cholinergic neurons (BFCNs), abnormal metabolism of the amyloid precursor protein (APP), amyloid beta-peptide (Aβ) depositions, and neurofibrillary tangles. According to the cholinergic hypothesis, dysfunction of acetylcholine-containing neurons in the basal forebrain contributes markedly to the cognitive decline observed in AD. In addition, the neurotrophic factor hypothesis posits that the loss nerve growth factor (NGF) signalling in AD may account for the vulnerability to atrophy of BFCNs and consequent impairment of cholinergic functions. Though acetylcholinesterase inhibitors provide only partial and symptomatic relief to AD patients, emerging data from in vivo magnetic resonance imaging (MRI) and positron emission tomography (PET) studies in mild cognitive impairment (MCI) and AD patients highlight the early involvement of BFCNs in MCI and the early phase of AD. These data support the cholinergic and neurotrophic hypotheses of AD and suggest new targets for AD therapy.Different mechanisms account for selective vulnerability of BFCNs to AD pathology, with regard to altered metabolism of APP and tau. In this review, we provide a general overview of the current knowledge of NGF and APP interplay, focusing on the role of APP in regulating NGF receptors trafficking/signalling and on the involvement of NGF in modulating phosphorylation of APP, which in turn controls APP intracellular trafficking and processing. Moreover, we highlight the consequences of APP interaction with p75NTR and TrkA receptor, which share the same binding site within the APP juxta-membrane domain. We underline the importance of insulin dysmetabolism in AD pathology, in the light of our recent data showing that overlapping intracellular signalling pathways stimulated by NGF or insulin can be compensatory. In particular, NGF-based signalling is able to ameliorates deficiencies in insulin signalling in the medial septum of 3×Tg-AD mice. Finally, we present an overview of NGF-regulated microRNAs (miRNAs). These small non-coding RNAs are involved in post-transcriptional regulation of gene expression , and we focus on a subset that are specifically deregulated in AD and thus potentially contribute to its pathology.
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Affiliation(s)
- Viviana Triaca
- Institute of Biochemistry and Cell Biology (IBBC), National Research Council (CNR), Campus A. Buzzati-Traverso, Monterotondo, RM, Italy
| | - Francesca Ruberti
- Institute of Biochemistry and Cell Biology (IBBC), National Research Council (CNR), Campus A. Buzzati-Traverso, Monterotondo, RM, Italy
| | - Nadia Canu
- Institute of Biochemistry and Cell Biology (IBBC), National Research Council (CNR), Campus A. Buzzati-Traverso, Monterotondo, RM, Italy. .,Department of System Medicine, Section of Physiology, University of Rome "Tor Vergata", Rome, Italy.
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7
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Ojiakor O, Rylett R. Modulation of sodium-coupled choline transporter CHT function in health and disease. Neurochem Int 2020; 140:104810. [DOI: 10.1016/j.neuint.2020.104810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 06/16/2020] [Accepted: 07/09/2020] [Indexed: 12/27/2022]
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Cacabelos R. Pharmacogenetic considerations when prescribing cholinesterase inhibitors for the treatment of Alzheimer's disease. Expert Opin Drug Metab Toxicol 2020; 16:673-701. [PMID: 32520597 DOI: 10.1080/17425255.2020.1779700] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Cholinergic dysfunction, demonstrated in the late 1970s and early 1980s, led to the introduction of acetylcholinesterase inhibitors (AChEIs) in 1993 (Tacrine) to enhance cholinergic neurotransmission as the first line of treatment against Alzheimer's disease (AD). The new generation of AChEIs, represented by Donepezil (1996), Galantamine (2001) and Rivastigmine (2002), is the only treatment for AD to date, together with Memantine (2003). AChEIs are not devoid of side-effects and their cost-effectiveness is limited. An option to optimize the correct use of AChEIs is the implementation of pharmacogenetics (PGx) in the clinical practice. AREAS COVERED (i) The cholinergic system in AD, (ii) principles of AD PGx, (iii) PGx of Donepezil, Galantamine, Rivastigmine, Huperzine and other treatments, and (iv) practical recommendations. EXPERT OPINION The most relevant genes influencing AChEI efficacy and safety are APOE and CYPs. APOE-4 carriers are the worst responders to AChEIs. With the exception of Rivastigmine (UGT2B7, BCHE-K), the other AChEIs are primarily metabolized via CYP2D6, CYP3A4, and UGT enzymes, with involvement of ABC transporters and cholinergic genes (CHAT, ACHE, BCHE, SLC5A7, SLC18A3, CHRNA7) in most ethnic groups. Defective variants may affect the clinical response to AChEIs. PGx geno-phenotyping is highly recommended prior to treatment.
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Affiliation(s)
- Ramón Cacabelos
- Department of Genomic Medicine, EuroEspes Biomedical Research Center, International Center of Neuroscience and Genomic Medicine , Bergondo, Corunna, Spain
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9
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Barthet G, Mulle C. Presynaptic failure in Alzheimer's disease. Prog Neurobiol 2020; 194:101801. [PMID: 32428558 DOI: 10.1016/j.pneurobio.2020.101801] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/24/2020] [Accepted: 04/03/2020] [Indexed: 12/14/2022]
Abstract
Synaptic loss is the best correlate of cognitive deficits in Alzheimer's disease (AD). Extensive experimental evidence also indicates alterations of synaptic properties at the early stages of disease progression, before synapse loss and neuronal degeneration. A majority of studies in mouse models of AD have focused on post-synaptic mechanisms, including impairment of long-term plasticity, spine structure and glutamate receptor-mediated transmission. Here we review the literature indicating that the synaptic pathology in AD includes a strong presynaptic component. We describe the evidence indicating presynaptic physiological functions of the major molecular players in AD. These include the amyloid precursor protein (APP) and the two presenilin (PS) paralogs PS1 or PS2, genetically linked to the early-onset form of AD, in addition to tau which accumulates in a pathological form in the AD brain. Three main mechanisms participating in presynaptic functions are highlighted. APP fragments bind to presynaptic receptors (e.g. nAChRs and GABAB receptors), presenilins control Ca2+ homeostasis and Ca2+-sensors, and tau regulates the localization of presynaptic molecules and synaptic vesicles. We then discuss how impairment of these presynaptic physiological functions can explain or forecast the hallmarks of synaptic impairment and associated dysfunction of neuronal circuits in AD. Beyond the physiological roles of the AD-related proteins, studies in AD brains also support preferential presynaptic alteration. This review features presynaptic failure as a strong component of pathological mechanisms in AD.
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Affiliation(s)
- Gael Barthet
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, France
| | - Christophe Mulle
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, France.
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10
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Truong PH, Ciccotosto GD, Cappai R. Analysis of Motor Function in Amyloid Precursor-Like Protein 2 Knockout Mice: The Effects of Ageing and Sex. Neurochem Res 2018; 44:1356-1366. [PMID: 30362021 DOI: 10.1007/s11064-018-2669-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/18/2018] [Accepted: 10/20/2018] [Indexed: 12/19/2022]
Abstract
The amyloid precursor protein (APP) is a member of a conserved gene family that includes the amyloid precursor-like proteins 1 (APLP1) and 2 (APLP2). APP and APLP2 share a high degree of similarity, and have overlapping patterns of spatial and temporal expression in the central and peripheral tissues, in particular at the neuromuscular junction. APP-family knockout (KO) studies have helped elucidate aspects of function and functional redundancy amongst the APP-family members. In the present study, we investigated motor performance of APLP2-KO mice and the effect sex differences and age-related changes have on motor performance. APLP2-KO and WT (on C57Bl6 background) littermates control mice from 8 (young adulthood) to 48 weeks (middle age) were investigated. Analysis of motor neuron and muscle morphology showed APLP2-KO females but not males, had less age-related motor function impairments. We observed age and sex differences in both motor neuron number and muscle fiber size distribution for APLP2-KO mice compared to WT (C57Bl6). These alterations in the motor neuron number and muscle fiber distribution pattern may explain why female APLP2-KO mice have far better motor function behaviour during ageing.
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Affiliation(s)
- Phan H Truong
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Giuseppe D Ciccotosto
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia
| | - Roberto Cappai
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, VIC, 3010, Australia.
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11
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Colombo A, Hsia HE, Wang M, Kuhn PH, Brill MS, Canevazzi P, Feederle R, Taveggia C, Misgeld T, Lichtenthaler SF. Non-cell-autonomous function of DR6 in Schwann cell proliferation. EMBO J 2018; 37:embj.201797390. [PMID: 29459438 DOI: 10.15252/embj.201797390] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 12/20/2017] [Accepted: 01/16/2018] [Indexed: 12/21/2022] Open
Abstract
Death receptor 6 (DR6) is an orphan member of the TNF receptor superfamily and controls cell death and differentiation in a cell-autonomous manner in different cell types. Here, we report an additional non-cell-autonomous function for DR6 in the peripheral nervous system (PNS). DR6-knockout (DR6 KO) mice showed precocious myelination in the PNS Using an in vitro myelination assay, we demonstrate that neuronal DR6 acts in trans on Schwann cells (SCs) and reduces SC proliferation and myelination independently of its cytoplasmic death domain. Mechanistically, DR6 was found to be cleaved in neurons by "a disintegrin and metalloprotease 10" (ADAM10), releasing the soluble DR6 ectodomain (sDR6). Notably, in the in vitro myelination assay, sDR6 was sufficient to rescue the DR6 KO phenotype. Thus, in addition to the cell-autonomous receptor function of full-length DR6, the proteolytically released sDR6 can unexpectedly also act as a paracrine signaling factor in the PNS in a non-cell-autonomous manner during SC proliferation and myelination. This new mode of DR6 signaling will be relevant in future attempts to target DR6 in disease settings.
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Affiliation(s)
- Alessio Colombo
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Hung-En Hsia
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Neuroproteomics, Klinikum rechts der Isar, and Institute for Advanced Study, Technical University Munich, Munich, Germany
| | - Mengzhe Wang
- Institute of Neuronal Cell Biology, Technical University of Munich, Munich, Germany
| | - Peer-Hendrik Kuhn
- Neuroproteomics, Klinikum rechts der Isar, and Institute for Advanced Study, Technical University Munich, Munich, Germany
| | - Monika S Brill
- Institute of Neuronal Cell Biology, Technical University of Munich, Munich, Germany
| | - Paolo Canevazzi
- Division of Neuroscience, INSPE at San Raffaele Scientific Institute, Milan, Italy
| | - Regina Feederle
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Institute for Diabetes and Obesity, Monoclonal Antibody Research Group, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Munich, Germany.,Munich Center for Systems Neurology (SyNergy), Munich, Germany
| | - Carla Taveggia
- Division of Neuroscience, INSPE at San Raffaele Scientific Institute, Milan, Italy
| | - Thomas Misgeld
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Institute of Neuronal Cell Biology, Technical University of Munich, Munich, Germany.,Munich Center for Systems Neurology (SyNergy), Munich, Germany.,Center for Integrated Protein Sciences (CIPSM), Munich, Germany
| | - Stefan F Lichtenthaler
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany .,Neuroproteomics, Klinikum rechts der Isar, and Institute for Advanced Study, Technical University Munich, Munich, Germany.,Munich Center for Systems Neurology (SyNergy), Munich, Germany
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12
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Cuddy LK, Seah C, Pasternak SH, Rylett RJ. Amino-Terminal β-Amyloid Antibody Blocks β-Amyloid-Mediated Inhibition of the High-Affinity Choline Transporter CHT. Front Mol Neurosci 2017; 10:361. [PMID: 29163036 PMCID: PMC5681948 DOI: 10.3389/fnmol.2017.00361] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 10/19/2017] [Indexed: 11/13/2022] Open
Abstract
Alzheimer's disease (AD) is a common age-related neurodegenerative disorder that is characterized by progressive cognitive decline. The deficits in cognition and attentional processing that are observed clinically in AD are linked to impaired function of cholinergic neurons that release the neurotransmitter acetylcholine (ACh). The high-affinity choline transporter (CHT) is present at the presynaptic cholinergic nerve terminal and is responsible for the reuptake of choline produced by hydrolysis of ACh following its release. Disruption of CHT function leads to decreased choline uptake and ACh synthesis, leading to impaired cholinergic neurotransmission. We report here that cell-derived β-amyloid peptides (Aβ) decrease choline uptake activity and cell surface CHT protein levels in SH-SY5Y neural cells. Moreover, we make the novel observation that the amount of CHT protein localizing to early endosomes and lysosomes is decreased significantly in cells that have been treated with cell culture medium that contains Aβ peptides released from neural cells. The Aβ-mediated loss of CHT proteins from lysosomes is prevented by blocking lysosomal degradation of CHT with the lysosome inhibitor bafilomycin A1 (BafA1). BafA1 also attenuated the Aβ-mediated decrease in CHT cell surface expression. Interestingly, however, lysosome inhibition did not block the effect of Aβ on CHT activity. Importantly, neutralizing Aβ using an anti-Aβ antibody directed at the N-terminal amino acids 1-16 of Aβ, but not by an antibody directed at the mid-region amino acids 22-35 of Aβ, attenuates the effect of Aβ on CHT activity and trafficking. This indicates that a specific N-terminal Aβ epitope, or specific conformation of soluble Aβ, may impair CHT activity. Therefore, Aβ immunotherapy may be a more effective therapeutic strategy for slowing the progression of cognitive decline in AD than therapies designed to promote CHT cell surface levels.
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Affiliation(s)
- Leah K Cuddy
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada.,Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Claudia Seah
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Stephen H Pasternak
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - R Jane Rylett
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
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13
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Zhang F, Gannon M, Chen Y, Zhou L, Jiao K, Wang Q. The amyloid precursor protein modulates α 2A-adrenergic receptor endocytosis and signaling through disrupting arrestin 3 recruitment. FASEB J 2017. [PMID: 28646018 DOI: 10.1096/fj.201700346r] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The amyloid precursor protein (APP) has long been appreciated for its role in Alzheimer's disease (AD) pathology. However, less is known about the physiologic function of APP outside of AD. Particularly, whether and how APP may regulate functions of cell surface receptors, including GPCRs, remains largely unclear. In this study, we identified a novel direct interaction between APP and the α2A-adrenergic receptor (α2AAR) that occurs at the intracellular domains of both proteins. The APP interaction with α2AAR is promoted by agonist stimulation and competes with arrestin 3 binding to the receptor. Consequently, the presence of APP attenuates α2AAR internalization and desensitization, which are arrestin-dependent processes. Furthermore, in neuroblastoma neuro-2A cells and primary superior cervical ganglion neurons, where APP is highly expressed, the lack of APP leads to a dramatic increase in plasma membrane recruitment of endogenous arrestin 3 following α2AAR activation. Concomitantly, agonist-induced internalization of α2AAR is significantly enhanced in these neuronal cells. Our study provided the first evidence that APP fine tunes GPCR signaling and trafficking. Given the important role of α2AAR in controlling norepinephrine release and response, this novel regulation of α2AAR by APP may have an impact on modulation of noradrenergic activity and sympathetic tone.-Zhang, F., Gannon, M., Chen, Y., Zhou, L., Jiao, K., Wang, Q. The amyloid precursor protein modulates α2A-adrenergic receptor endocytosis and signaling through disrupting arrestin 3 recruitment.
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Affiliation(s)
- Fang Zhang
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Mary Gannon
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Yunjia Chen
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Lufang Zhou
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kai Jiao
- Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Qin Wang
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, USA;
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14
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Han K, Müller UC, Hülsmann S. Amyloid-precursor Like Proteins APLP1 and APLP2 Are Dispensable for Normal Development of the Neonatal Respiratory Network. Front Mol Neurosci 2017; 10:189. [PMID: 28690498 PMCID: PMC5479907 DOI: 10.3389/fnmol.2017.00189] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 05/29/2017] [Indexed: 11/13/2022] Open
Abstract
Recent studies using animal models indicated that the members of the amyloid precursor protein (APP) gene family are important for the formation, maintenance, and plasticity of synapses. Despite this, the specific role of the APP homologs APLP1 and APLP2 within the CNS and PNS is still poorly understood. In contrast to the subtle phenotypes of single mutants, double knockout mice (DKO) lacking APP/APLP2 or APLP1/APLP2 die within the first day after birth. Whereas APP/APLP2-DKO mice show severe deficits of neuromuscular morphology and transmission, the underlying cause of lethality of APLP1/APLP2-DKO mice remains unclear. Since expression of both proteins was confirmed by in situ hybridization, we aimed to test the role of APLP1/APLP2 in the formation and maintenance of synapses in the brainstem, and assessed a potential dysfunction of the most vital central neuronal network in APLP1/APLP2-DKO mice by analyzing the respiratory network of the medulla. We performed in vivo unrestrained whole body plethysmography in newborn APLP1/APLP2-DKO mice at postnatal day zero. Additionally, we directly tested the activity of the respiratory network in an acute slice preparation that includes the pre-Bötzinger complex. In both sets of experiments, no significant differences were detected regarding respiratory rate and cycle variability, strongly arguing against central respiratory problems as the primary cause of death of APLP1/APLP2-DKO mice. Thus, we conclude that APLP1 and APLP2 are dispensable for the development of the network and the generation of a normal breathing rhythm.
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Affiliation(s)
- Kang Han
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg UniversityHeidelberg, Germany
| | - Ulrike C Müller
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg UniversityHeidelberg, Germany
| | - Swen Hülsmann
- Klinik für Anästhesiologie, Universitätsmedizin GöttingenGöttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB)Göttingen, Germany
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15
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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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16
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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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17
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Chen M, Wang J, Jiang J, Zheng X, Justice NJ, Wang K, Ran X, Li Y, Huo Q, Zhang J, Li H, Lu N, Wang Y, Zheng H, Long C, Yang L. APP modulates KCC2 expression and function in hippocampal GABAergic inhibition. eLife 2017; 6. [PMID: 28054918 PMCID: PMC5224924 DOI: 10.7554/elife.20142] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 12/16/2016] [Indexed: 12/14/2022] Open
Abstract
Amyloid precursor protein (APP) is enriched at the synapse, but its synaptic function is still poorly understood. We previously showed that GABAergic short-term plasticity is impaired in App knock-out (App-/-) animals, but the precise mechanism by which APP regulates GABAergic synaptic transmission has remained elusive. Using electrophysiological, biochemical, moleculobiological, and pharmacological analysis, here we show that APP can physically interact with KCC2, a neuron-specific K+-Cl- cotransporter that is essential for Cl- homeostasis and fast GABAergic inhibition. APP deficiency results in significant reductions in both total and membrane KCC2 levels, leading to a depolarizing shift in the GABA reversal potential (EGABA). Simultaneous measurement of presynaptic action potentials and inhibitory postsynaptic currents (IPSCs) in hippocampal neurons reveals impaired unitary IPSC amplitudes attributable to a reduction in α1 subunit levels of GABAAR. Importantly, restoration of normal KCC2 expression and function in App-/- mice rescues EGABA, GABAAR α1 levels and GABAAR mediated phasic inhibition. We show that APP functions to limit tyrosine-phosphorylation and ubiquitination and thus subsequent degradation of KCC2, providing a mechanism by which APP influences KCC2 abundance. Together, these experiments elucidate a novel molecular pathway in which APP regulates, via protein-protein interaction with KCC2, GABAAR mediated inhibition in the hippocampus. DOI:http://dx.doi.org/10.7554/eLife.20142.001 Alzheimer’s disease is the most common form of dementia. One of the hallmarks of the disease is the formation of sticky protein clumps called amyloid plaques in the brain. These plaques are formed from specific fragments of a protein called APP. The intact form of APP is essential for synapses (the junctions across which neurons transmit signals) to form and work correctly. The hippocampus is one of the first brain regions to be affected in Alzheimer’s disease and is important for forming memories and emotions. In the hippocampus, GABAA receptors at synapses normally tightly regulate synaptic signaling by reducing the ability of the receiving neuron to respond, but this inhibition is disrupted in Alzheimer’s disease. Studies suggest that APP can affect how GABAA receptors transmit signals, but it is not known how it does so. One possibility is that APP regulates a protein called KCC2 that helps to maintain the inhibitory effect of GABAA receptors. To investigate this, Chen et al. genetically modified mice to lack the gene that produces APP. These mice had a lower level of KCC2 in their hippocampus than normal mice, and their GABAA receptors were less able to inhibit synaptic signaling. Further experiments demonstrated that APP physically interacts with KCC2 and maintains normal levels of the protein by preventing it from being chemically modified and degraded. Chen et al. also showed that treating mice that lack APP with specific compounds can restore KCC2 activity and return the behavior of synaptic GABAA receptors to normal. Future studies in mice (and eventually people) that exhibit symptoms of Alzheimer's disease will help to determine whether KCC2 is important in the development of the disease. If so, modifying the levels of the KCC2 protein in the brain could potentially help to slow down memory loss in Alzheimer’s disease. DOI:http://dx.doi.org/10.7554/eLife.20142.002
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Affiliation(s)
- Ming Chen
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Jinzhao Wang
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Jinxiang Jiang
- School of Psychology and Center for Studies of Psychological Application, South China Normal University, Guangzhou, China.,Brain Science Institute, South China Normal University, Guangzhou, China
| | - Xingzhi Zheng
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Nicholas J Justice
- Institute of Molecular Medicine, University of Texas Health Sciences Center, Houston, United States
| | - Kun Wang
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Xiangqian Ran
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Yi Li
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Qingwei Huo
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Jiajia Zhang
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Hongmei Li
- Huffington Center on Aging, Baylor College of Medicine, Houston, United States
| | - Nannan Lu
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Ying Wang
- School of Life Sciences, South China Normal University, Guangzhou, China
| | - Hui Zheng
- Huffington Center on Aging, Baylor College of Medicine, Houston, United States
| | - Cheng Long
- School of Life Sciences, South China Normal University, Guangzhou, China.,Brain Science Institute, South China Normal University, Guangzhou, China
| | - Li Yang
- School of Psychology and Center for Studies of Psychological Application, South China Normal University, Guangzhou, China.,Brain Science Institute, South China Normal University, Guangzhou, China.,Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou, China
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18
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Cardoso S, Seiça R, Moreira PI. Diabesity and Brain Energy Metabolism: The Case of Alzheimer's Disease. ADVANCES IN NEUROBIOLOGY 2017; 19:117-150. [PMID: 28933063 DOI: 10.1007/978-3-319-63260-5_5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
It is widely accepted that high calorie diets and a sedentary lifestyle sturdily influence the incidence and outcome of type 2 diabetes and obesity, which can occur simultaneously, a situation called diabesity. Tightly linked with metabolic and energy regulation, a close association between diabetes and Alzheimer's disease (AD) has been proposed. Among the common pathogenic mechanisms that underpin both conditions, insulin resistance, brain glucose hypometabolism, and metabolic dyshomeostasis appear to have a pivotal role. This century is an unprecedented diabetogenic period in human history, so therapeutic strategies and/or approaches to control and/or revert this evolving epidemic is of utmost importance. This chapter will make a brief contextualization about the impact that diabetes and obesity can exert in brain structure and function alongside with a brief survey about the role of insulin in normal brain function, exploring its roles in cognition and brain glucose metabolism. Later, attention will be given to the intricate relation of diabesity, insulin resistance, and AD. Finally, both pharmacological and lifestyle interventions will also be reviewed as strategies aimed at fighting diabesity and/or AD-related metabolic effects.
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Affiliation(s)
- Susana Cardoso
- Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal.
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
| | - Raquel Seiça
- Institute of Physiology, Institute for Biomedical Imaging and Life Sciences-IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Paula I Moreira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Institute of Physiology, Institute for Biomedical Imaging and Life Sciences-IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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19
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Ferreira-Vieira TH, Guimaraes IM, Silva FR, Ribeiro FM. Alzheimer's disease: Targeting the Cholinergic System. Curr Neuropharmacol 2016; 14:101-15. [PMID: 26813123 PMCID: PMC4787279 DOI: 10.2174/1570159x13666150716165726] [Citation(s) in RCA: 861] [Impact Index Per Article: 107.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 07/01/2015] [Accepted: 07/14/2015] [Indexed: 12/16/2022] Open
Abstract
Acetylcholine (ACh) has a crucial role in the peripheral and central nervous
systems. The enzyme choline acetyltransferase (ChAT) is responsible for
synthesizing ACh from acetyl-CoA and choline in the cytoplasm and the vesicular
acetylcholine transporter (VAChT) uptakes the neurotransmitter into synaptic
vesicles. Following depolarization, ACh undergoes exocytosis reaching the
synaptic cleft, where it can bind its receptors, including muscarinic and
nicotinic receptors. ACh present at the synaptic cleft is promptly hydrolyzed by
the enzyme acetylcholinesterase (AChE), forming acetate and choline, which is
recycled into the presynaptic nerve terminal by the high-affinity choline
transporter (CHT1). Cholinergic neurons located in the basal forebrain,
including the neurons that form the nucleus basalis of Meynert, are severely
lost in Alzheimer’s disease (AD). AD is the most ordinary cause of dementia
affecting 25 million people worldwide. The hallmarks of the disease are the
accumulation of neurofibrillary tangles and amyloid plaques. However, there is
no real correlation between levels of cortical plaques and AD-related cognitive
impairment. Nevertheless, synaptic loss is the principal correlate of disease
progression and loss of cholinergic neurons contributes to memory and attention
deficits. Thus, drugs that act on the cholinergic system represent a promising
option to treat AD patients.
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Affiliation(s)
| | | | | | - Fabiola M Ribeiro
- Departamento de Bioquimica e Imunologia, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
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20
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Both pre- and post-synaptic alterations contribute to aberrant cholinergic transmission in superior cervical ganglia of APP(-/-) mice. Neuropharmacology 2016; 110:493-502. [PMID: 27553120 DOI: 10.1016/j.neuropharm.2016.08.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 07/28/2016] [Accepted: 08/17/2016] [Indexed: 12/20/2022]
Abstract
Though amyloid precursor protein (APP) can potentially be cleaved to generate the pathological amyloid β peptide (Aβ), APP itself plays an important role in regulating neuronal activity. APP deficiency causes functional impairment in cholinergic synaptic transmission and cognitive performance. However, the mechanisms underlying altered cholinergic synaptic transmission in APP knock-out mice (APP(-/-)) are poorly understood. In this study, we conducted in vivo extracellular recording to investigate cholinergic compound action potentials (CAPs) of the superior cervical ganglion (SCG) in APP(-/-) and littermate wild-type (WT) mice. Our results demonstrate that APP not only regulates presynaptic activity, but also affects postsynaptic function at cholinergic synapses in SCG. APP deficiency reduces the number of vesicles in presynaptic terminalsand attenuatesthe amplitude of CAPs, likely due to dysfunction of high-affinity choline transporters. Pharmacological and biochemical examination showed that postsynaptic responsesmediated by α4β2 and α7 nicotinic acetylcholine receptors are reduced in the absence of APP. Our research provides evidences on how APP regulates cholinergic function and therefore may help to identify potential therapeutic targets to treat cholinergic dysfunction associated with Alzheimer's disease pathogenesis.
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21
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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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22
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Cuddy LK, Seah C, Pasternak SH, Rylett RJ. Differential regulation of the high-affinity choline transporter by wild-type and Swedish mutant amyloid precursor protein. J Neurochem 2015; 134:769-82. [DOI: 10.1111/jnc.13167] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 04/30/2015] [Accepted: 05/06/2015] [Indexed: 01/18/2023]
Affiliation(s)
- Leah K. Cuddy
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario Canada
| | - Claudia Seah
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
| | - Stephen H. Pasternak
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario Canada
- Department of Clinical Neurological Sciences; Schulich School of Medicine & Dentistry; University of Western Ontario; London Ontario Canada
| | - Rebecca Jane Rylett
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario Canada
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23
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Abstract
Members of the low-density lipoprotein (LDL) receptor gene family have a diverse set of biological functions that transcend lipid metabolism. Lipoprotein receptors have broad effects in both the developing and adult brain and participate in synapse development, cargo trafficking, and signal transduction. In addition, several family members play key roles in Alzheimer's disease (AD) pathogenesis and neurodegeneration. This Review summarizes our current understanding of the role lipoprotein receptors play in CNS function and AD pathology, with a special emphasis on amyloid-independent roles in endocytosis and synaptic dysfunction.
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24
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Santoro ML, Santos CM, Ota VK, Gadelha A, Stilhano RS, Diana MC, Silva PN, Spíndola LMN, Melaragno MI, Bressan RA, Han SW, Abílio VC, Belangero SI. Expression profile of neurotransmitter receptor and regulatory genes in the prefrontal cortex of spontaneously hypertensive rats: relevance to neuropsychiatric disorders. Psychiatry Res 2014; 219:674-9. [PMID: 25041985 DOI: 10.1016/j.psychres.2014.05.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 04/22/2014] [Accepted: 05/18/2014] [Indexed: 12/12/2022]
Abstract
The spontaneously hypertensive rat (SHR) strain was shown to be a useful animal model to study several behavioral, pathophysiological and pharmacological aspects of schizophrenia and attention-deficit/hyperactivity disorder. To further understand the genetic underpinnings of this model, our primary goal in this study was to compare the gene expression profile of neurotransmitter receptors and regulators in the prefrontal cortex (PFC) and nucleus accumbens (NAcc) of SHR and Wistar rats (control group). In addition, we investigated DNA methylation pattern of promoter region of the genes differentially expressed. We performed gene expression analysis using a PCRarray technology, which simultaneously measures the expression of 84 genes related to neurotransmission. Four genes were significantly downregulated in the PFC of SHR compared to Wistar rats (Gad2, Chrnb4, Slc5a7, and Qrfpr) and none in nucleus accumbens. Gad2 and Qrfpr have CpG islands in their promoter region. For both, the promoter region was hypomethylated in SHR group, and probably this mechanism is not related with the downregulation of these genes. In summary, we identified genes that are downregulated in the PFC of SHR, and might be related to the behavioral abnormalities exhibited by this strain.
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Affiliation(s)
- Marcos Leite Santoro
- Genetics Division, Department of Morphology and Genetics, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil; Interdisciplinary Laboratory of Clinical Neurosciences (LiNC), Sao Paulo, Brazil
| | - Camila Maurício Santos
- Interdisciplinary Laboratory of Clinical Neurosciences (LiNC), Sao Paulo, Brazil; Department of Psychiatry, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Vanessa Kiyomi Ota
- Genetics Division, Department of Morphology and Genetics, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil; Interdisciplinary Laboratory of Clinical Neurosciences (LiNC), Sao Paulo, Brazil
| | - Ary Gadelha
- Interdisciplinary Laboratory of Clinical Neurosciences (LiNC), Sao Paulo, Brazil; Department of Psychiatry, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Roberta Sessa Stilhano
- Department of Biophysics and Investigation Center for Gene Therapy, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Mariana Cepollaro Diana
- Interdisciplinary Laboratory of Clinical Neurosciences (LiNC), Sao Paulo, Brazil; Department of Pharmacology, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Patrícia Natália Silva
- Genetics Division, Department of Morphology and Genetics, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil; Department of Psychiatry, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Letícia Maria Nery Spíndola
- Genetics Division, Department of Morphology and Genetics, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Maria Isabel Melaragno
- Genetics Division, Department of Morphology and Genetics, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Rodrigo Affonseca Bressan
- Interdisciplinary Laboratory of Clinical Neurosciences (LiNC), Sao Paulo, Brazil; Department of Psychiatry, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Sang Won Han
- Department of Biophysics and Investigation Center for Gene Therapy, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Vanessa Costhek Abílio
- Interdisciplinary Laboratory of Clinical Neurosciences (LiNC), Sao Paulo, Brazil; Department of Pharmacology, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Sintia Iole Belangero
- Genetics Division, Department of Morphology and Genetics, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil; Interdisciplinary Laboratory of Clinical Neurosciences (LiNC), Sao Paulo, Brazil; Department of Psychiatry, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil.
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25
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Weyer SW, Zagrebelsky M, Herrmann U, Hick M, Ganss L, Gobbert J, Gruber M, Altmann C, Korte M, Deller T, Müller UC. Comparative analysis of single and combined APP/APLP knockouts reveals reduced spine density in APP-KO mice that is prevented by APPsα expression. Acta Neuropathol Commun 2014; 2:36. [PMID: 24684730 PMCID: PMC4023627 DOI: 10.1186/2051-5960-2-36] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 03/07/2014] [Indexed: 11/21/2022] Open
Abstract
Synaptic dysfunction and synapse loss are key features of Alzheimer's pathogenesis. Previously, we showed an essential function of APP and APLP2 for synaptic plasticity, learning and memory. Here, we used organotypic hippocampal cultures to investigate the specific role(s) of APP family members and their fragments for dendritic complexity and spine formation of principal neurons within the hippocampus. Whereas CA1 neurons from APLP1-KO or APLP2-KO mice showed normal neuronal morphology and spine density, APP-KO mice revealed a highly reduced dendritic complexity in mid-apical dendrites. Despite unaltered morphology of APLP2-KO neurons, combined APP/APLP2-DKO mutants showed an additional branching defect in proximal apical dendrites, indicating redundancy and a combined function of APP and APLP2 for dendritic architecture. Remarkably, APP-KO neurons showed a pronounced decrease in spine density and reductions in the number of mushroom spines. No further decrease in spine density, however, was detectable in APP/APLP2-DKO mice. Mechanistically, using APPsα-KI mice lacking transmembrane APP and expressing solely the secreted APPsα fragment we demonstrate that APPsα expression alone is sufficient to prevent the defects in spine density observed in APP-KO mice. Collectively, these studies reveal a combined role of APP and APLP2 for dendritic architecture and a unique function of secreted APPs for spine density.
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Affiliation(s)
- Sascha W Weyer
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
| | - Marta Zagrebelsky
- TU Braunschweig, Zoological Institute, Cellular Neurobiology, Spielmannstr. 7, Braunschweig D-38106, Germany
| | - Ulrike Herrmann
- TU Braunschweig, Zoological Institute, Cellular Neurobiology, Spielmannstr. 7, Braunschweig D-38106, Germany
| | - Meike Hick
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
| | - Lennard Ganss
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
- Present address: Department of Applied Tumor Biology, Ruprecht-Karls University Heidelberg, Institute of Pathology, University of Heidelberg, Heidelberg D-69120, Germany
| | - Julia Gobbert
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
| | - Morna Gruber
- Goethe University Frankfurt, Institute of Clinical Neuroanatomy, Neuroscience Center, Theodor-Stern-Kai 7, Frankfurt am Main D-60596, Germany
| | - Christine Altmann
- Goethe University Frankfurt, Institute of Clinical Neuroanatomy, Neuroscience Center, Theodor-Stern-Kai 7, Frankfurt am Main D-60596, Germany
| | - Martin Korte
- TU Braunschweig, Zoological Institute, Cellular Neurobiology, Spielmannstr. 7, Braunschweig D-38106, Germany
| | - Thomas Deller
- Goethe University Frankfurt, Institute of Clinical Neuroanatomy, Neuroscience Center, Theodor-Stern-Kai 7, Frankfurt am Main D-60596, Germany
| | - Ulrike C Müller
- Department of Bioinformatics and Functional Genomics, Ruprecht-Karls University Heidelberg, Institute of Pharmacy and Molecular Biotechnology, Im Neuenheimer Feld 364, Heidelberg D-69120, Germany
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Berry AS, Demeter E, Sabhapathy S, English BA, Blakely RD, Sarter M, Lustig C. Disposed to distraction: genetic variation in the cholinergic system influences distractibility but not time-on-task effects. J Cogn Neurosci 2014; 26:1981-91. [PMID: 24666128 DOI: 10.1162/jocn_a_00607] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Both the passage of time and external distraction make it difficult to keep attention on the task at hand. We tested the hypothesis that time-on-task and external distraction pose independent challenges to attention and that the brain's cholinergic system selectively modulates our ability to resist distraction. Participants with a polymorphism limiting cholinergic capacity (Ile89Val variant [rs1013940] of the choline transporter gene SLC5A7) and matched controls completed self-report measures of attention and a laboratory task that measured decrements in sustained attention with and without distraction. We found evidence that distraction and time-on-task effects are independent and that the cholinergic system is strongly linked to greater vulnerability to distraction. Ile89Val participants reported more distraction during everyday life than controls, and their task performance was more severely impacted by the presence of an ecologically valid video distractor (similar to a television playing in the background). These results are the first to demonstrate a specific impairment in cognitive control associated with the Ile89Val polymorphism and add to behavioral and cognitive neuroscience studies indicating the cholinergic system's critical role in overcoming distraction.
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27
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Cuddy LK, Winick-Ng W, Rylett RJ. Regulation of the high-affinity choline transporter activity and trafficking by its association with cholesterol-rich lipid rafts. J Neurochem 2013; 128:725-40. [PMID: 24127780 DOI: 10.1111/jnc.12490] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 10/10/2013] [Accepted: 10/14/2013] [Indexed: 01/07/2023]
Abstract
The sodium-coupled, hemicholinium-3-sensitive, high-affinity choline transporter (CHT) is responsible for transport of choline into cholinergic nerve terminals from the synaptic cleft following acetylcholine release and hydrolysis. In this study, we address regulation of CHT function by plasma membrane cholesterol. We show for the first time that CHT is concentrated in cholesterol-rich lipid rafts in both SH-SY5Y cells and nerve terminals from mouse forebrain. Treatment of SH-SY5Y cells expressing rat CHT with filipin, methyl-β-cyclodextrin (MβC) or cholesterol oxidase significantly decreased choline uptake. In contrast, CHT activity was increased by addition of cholesterol to membranes using cholesterol-saturated MβC. Kinetic analysis of binding of [(3)H]hemicholinium-3 to CHT revealed that reducing membrane cholesterol with MβC decreased both the apparent binding affinity (KD) and maximum number of binding sites (Bmax ); this was confirmed by decreased plasma membrane CHT protein in lipid rafts in cell surface protein biotinylation assays. Finally, the loss of cell surface CHT associated with lipid raft disruption was not because of changes in CHT internalization. In summary, we provide evidence that CHT association with cholesterol-rich rafts is critical for transporter function and localization. Alterations in plasma membrane cholesterol cholinergic nerve terminals could diminish cholinergic transmission by reducing choline availability for acetylcholine synthesis. The sodium-coupled choline transporter CHT moves choline into cholinergic nerve terminals to serve as substrate for acetylcholine synthesis. We show for the first time that CHT is concentrated in cholesterol-rich lipid rafts, and decreasing membrane cholesterol significantly reduces both choline uptake activity and cell surface CHT protein levels. CHT association with cholesterol-rich rafts is critical for its function, and alterations in plasma membrane cholesterol could diminish cholinergic transmission by reducing choline availability for acetylcholine synthesis.
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Affiliation(s)
- Leah K Cuddy
- Molecular Brain Research Group, Robarts Research Institute, Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
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28
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APP regulates NGF receptor trafficking and NGF-mediated neuronal differentiation and survival. PLoS One 2013; 8:e80571. [PMID: 24224055 PMCID: PMC3815101 DOI: 10.1371/journal.pone.0080571] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 10/14/2013] [Indexed: 11/30/2022] Open
Abstract
β-amyloid precursor protein (APP) is a key factor in Alzheimer's disease (AD) but its physiological function is largely undetermined. APP has been found to regulate retrograde transport of nerve growth factor (NGF), which plays a crucial role in mediating neuronal survival and differentiation. Herein, we reveal the mechanism underlying APP-mediated NGF trafficking, by demonstrating a direct interaction between APP and the two NGF receptors, TrkA and p75NTR. Downregulation of APP leads to reduced cell surface levels of TrkA/p75NTR and increased endocytosis of TrkA/p75NTR and NGF. In addition, APP-deficient cells manifest defects in neurite outgrowth and are more susceptible to Aβ-induced neuronal death at physiological levels of NGF. However, APP-deficient cells show better responses to NGF-stimulated differentiation and survival than control cells. This may be attributed to increased receptor endocytosis and enhanced activation of Akt and MAPK upon NGF stimulation in APP-deficient cells. Together, our results suggest that APP mediates endocytosis of NGF receptors through direct interaction, thereby regulating endocytosis of NGF and NGF-induced downstream signaling pathways for neuronal survival and differentiation.
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29
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Peters HL, Yan Y, Solheim JC. APLP2 regulates the expression of MHC class I molecules on irradiated Ewing's sarcoma cells. Oncoimmunology 2013; 2:e26293. [PMID: 24353913 PMCID: PMC3862638 DOI: 10.4161/onci.26293] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 08/27/2013] [Accepted: 08/27/2013] [Indexed: 01/06/2023] Open
Abstract
Ewing's sarcoma (EWS) is a pediatric cancer that is conventionally treated by surgery, chemotherapy, and radiation therapy. Innovative immunotherapies to treat EWS are currently under development. Unfortunately for EWS patients, when the disease is found to be resistant to current therapeutic approaches, the prognosis is predictably grim. Radiation therapy and immunotherapy could potentially synergize in the eradication of EWS, as some studies have previously shown that irradiation increases the presence of immune receptors, including MHC class I molecules, on the surface of tumor cells. However, EWS cells have been reported to express low levels of MHC class I molecules, a phenotype that would inhibit T-cell mediated lysis. We have previously demonstrated that the transgene-driven overexpression of amyloid β (A4) precursor-like protein 2 (APLP2) reduces the expression of MHC class I molecules on the surface of human cervical carcinoma HeLa cells. We thus examined whether endogenously expressed APLP2 downregulates MHC class I expression on EWS cells, particularly upon irradiation. We found that irradiation induces the relocalization of APLP2 and MHC class I molecules on the surface of EWS cells, redistributing cells from subpopulations with relatively low APLP2 and high MHC class I into subpopulations with relatively high APLP2 and low MHC class I surface expression. Consistent with these findings, the transfection of an APLP2-targeting siRNA into EWS cells increased MHC class I expression on the cell surface. Furthermore, APLP2 was found by co-immunoprecipitation to bind to MHC class I molecules. Taken together, these findings suggest that APLP2 inhibits MHC class I expression on the surface of irradiated EWS cells by a mechanism that involves APLP2/MHC class I interactions. Thus, therapeutic strategies that limit APLP2 expression may boost the ability of T cells to recognize and eradicate EWS in patients.
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Affiliation(s)
- Haley L Peters
- Eppley Institute; University of Nebraska Medical Center; Omaha, NE USA
| | - Ying Yan
- Eppley Institute; University of Nebraska Medical Center; Omaha, NE USA
| | - Joyce C Solheim
- Eppley Institute; University of Nebraska Medical Center; Omaha, NE USA ; Department of Biochemistry and Molecular Biology; University of Nebraska Medical Center; Omaha, NE USA ; Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha, NE USA
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30
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Abstract
Biochemical and genetic evidence establishes a central role of the amyloid precursor protein (APP) in Alzheimer disease (AD) pathogenesis. Biochemically, deposition of the β-amyloid (Aβ) peptides produced from proteolytic processing of APP forms the defining pathological hallmark of AD; genetically, both point mutations and duplications of wild-type APP are linked to a subset of early onset of familial AD (FAD) and cerebral amyloid angiopathy. As such, the biological functions of APP and its processing products have been the subject of intense investigation, and the past 20+ years of research have met with both excitement and challenges. This article will review the current understanding of the physiological functions of APP in the context of APP family members.
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Affiliation(s)
- Ulrike C Müller
- Institute for Pharmacy and Molecular Biotechnology, University of Heidelberg, D-69120 Heidelberg, Germany.
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31
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Amyloid β precursor protein as a molecular target for amyloid β--induced neuronal degeneration in Alzheimer's disease. Neurobiol Aging 2013; 34:2525-37. [PMID: 23714735 DOI: 10.1016/j.neurobiolaging.2013.04.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/17/2013] [Accepted: 04/20/2013] [Indexed: 11/23/2022]
Abstract
A role of amyloid β (Aβ) peptide aggregation and deposition in Alzheimer's disease (AD) pathogenesis is widely accepted. Significantly, abnormalities induced by aggregated Aβ have been linked to synaptic and neuritic degeneration, consistent with the "dying-back" pattern of degeneration that characterizes neurons affected in AD. However, molecular mechanisms underlying the toxic effect of aggregated Aβ remain elusive. In the last 2 decades, a variety of aggregated Aβ species have been identified and their toxic properties demonstrated in diverse experimental systems. Concurrently, specific Aβ assemblies have been shown to interact and misregulate a growing number of molecular effectors with diverse physiological functions. Such pleiotropic effects of aggregated Aβ posit a mayor challenge for the identification of the most cardinal Aβ effectors relevant to AD pathology. In this review, we discuss recent experimental evidence implicating amyloid β precursor protein (APP) as a molecular target for toxic Aβ assemblies. Based on a significant body of pathologic observations and experimental evidence, we propose a novel pathologic feed-forward mechanism linking Aβ aggregation to abnormalities in APP processing and function, which in turn would trigger the progressive loss of neuronal connectivity observed early in AD.
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32
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The presynaptic choline transporter imposes limits on sustained cortical acetylcholine release and attention. J Neurosci 2013; 33:2326-37. [PMID: 23392663 DOI: 10.1523/jneurosci.4993-12.2013] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Functional variation in the gene encoding the presynaptic choline transporter (CHT) has been linked to attention-deficit/hyperactivity disorder. Here, we report that a heterozygous deletion in the CHT gene in mice (CHT(+/-)) limits the capacity of cholinergic neurons to sustain acetylcholine (ACh) release and attentional performance. Cortical microdialysis and amperometric methods revealed that, whereas wild-type and CHT(+/-) animals support equivalent basal ACh release and choline clearance, CHT(+/-) animals exhibit a significant inability to elevate extracellular ACh following basal forebrain stimulation, in parallel with a diminished choline clearance capacity following cessation of stimulation. Consistent with these findings, the density of CHTs in cortical synaptosomal plasma membrane-enriched fractions from unstimulated CHT(+/-) animals matched those observed in wild-type animals despite reductions in CHT levels in total extracts, achieved via a redistribution of CHT from vesicle pools. As a consequence, in CHT(+/-) animals, basal forebrain stimulation was unable to mobilize wild-type quantities of CHT to the plasma membrane. In behavioral studies, CHT(+/-) mice were impaired in performing a sustained attention task known to depend on cortical cholinergic activity. In wild-type mice, but not CHT(+/-) mice, attentional performance increased the density of CHTs in the synaptosomal membrane in the right frontal cortex. Basal CHT levels in vesicle-enriched membranes predicted the degree of CHT mobilization as well as individual variations in performance on the sustained attention task. Our findings demonstrate biochemical and physiological alterations that underlie cognitive impairments associated with genetically imposed reductions in choline uptake capacity.
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Abstract
Compelling evidence from in vivo model systems within the past decade shows that the APP family of proteins is important for synaptic development and function in the central and peripheral nervous systems. The synaptic role promises to be complex and multifaceted for several reasons. The three family members have overlapping and redundant functions in mammals. They have both adhesive and signaling properties and may, in principle, act as both ligands and receptors. Moreover, they bind a multitude of synapse-specific proteins, and we predict that additional interacting protein partners will be discovered. Transgenic mice with modified or abolished expression of APP and APLPs have synaptic defects that are readily apparent. Studies of the neuromuscular junction (NMJ) in these transgenic mice have revealed molecular and functional deficits in neurotransmitter release, in organization of the postsynaptic receptors, and in coordinated intercellular development. The results summarized here from invertebrate and vertebrate systems confirm that the NMJ with its accessibility, large size, and homogeneity provides a model synapse for identifying and analyzing molecular pathways of APP actions.
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34
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Fanara P, Wong PYA, Husted KH, Liu S, Liu VM, Kohlstaedt LA, Riiff T, Protasio JC, Boban D, Killion S, Killian M, Epling L, Sinclair E, Peterson J, Price RW, Cabin DE, Nussbaum RL, Brühmann J, Brandt R, Christine CW, Aminoff MJ, Hellerstein MK. Cerebrospinal fluid-based kinetic biomarkers of axonal transport in monitoring neurodegeneration. J Clin Invest 2012; 122:3159-69. [PMID: 22922254 DOI: 10.1172/jci64575] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 07/12/2012] [Indexed: 12/14/2022] Open
Abstract
Progress in neurodegenerative disease research is hampered by the lack of biomarkers of neuronal dysfunction. We here identified a class of cerebrospinal fluid-based (CSF-based) kinetic biomarkers that reflect altered neuronal transport of protein cargo, a common feature of neurodegeneration. After a pulse administration of heavy water (2H2O), distinct, newly synthesized 2H-labeled neuronal proteins were transported to nerve terminals and secreted, and then appeared in CSF. In 3 mouse models of neurodegeneration, distinct 2H-cargo proteins displayed delayed appearance and disappearance kinetics in the CSF, suggestive of aberrant transport kinetics. Microtubule-modulating pharmacotherapy normalized CSF-based kinetics of affected 2H-cargo proteins and ameliorated neurodegenerative symptoms in mice. After 2H2O labeling, similar neuronal transport deficits were observed in CSF of patients with Parkinson's disease (PD) compared with non-PD control subjects, which indicates that these biomarkers are translatable and relevant to human disease. Measurement of transport kinetics may provide a sensitive method to monitor progression of neurodegeneration and treatment effects.
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35
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Peroxynitrite donor SIN-1 alters high-affinity choline transporter activity by modifying its intracellular trafficking. J Neurosci 2012; 32:5573-84. [PMID: 22514319 DOI: 10.1523/jneurosci.5235-11.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Sodium-coupled, high-affinity choline transporters (CHTs) are inhibited by 3-morpholinosydnonimine (SIN-1) [peroxynitrite (ONOO⁻) donor]; ONOO⁻ can be produced from nitric oxide and reactive oxygen species during neurodegeneration. SIN-1 rapidly increases CHT internalization from the cell surface, and this correlates with decreased choline uptake. This study addresses mechanisms by which SIN-1 inhibits CHT function in human neuronal SH-SY5Y cells. Thus, mutant L531A-CHT, which does not constitutively internalize into cells by a clathrin-mediated process, is resistant to SIN-1 effects. This suggests that CHT inhibition is not due to oxidative-nitrosative inactivation of the protein and that decreased levels of cell surface CHT in SIN-1-treated cells is related to alterations in its trafficking and subcellular disposition. Dominant-negative proteins AP180C and dynamin-K44A, which interfere with clathrin-mediated and dynamin-dependent endocytosis, respectively, attenuate CHT inhibition by SIN-1. CHT in both vehicle- and SIN-1-treated cells colocalizes with Rab7, Rab9, and Lamp-1 in late endosomes and lysosomes to a similar extent. Lysosome inhibitors increase choline uptake, suggesting that CHT proteins are normally degraded by lysosomes, and this is not altered by oxidative stress. Unexpectedly, inhibitors of proteasomes, but not lysosomes, attenuate SIN-1-mediated inhibition of choline uptake, indicating that proteasomal degradation plays a role in regulating CHT disposition in SIN-1-treated cells. SIN-1 treatment also enhances CHT ubiquitination. Thus, CHT inhibition in SIN-1-treated cells is mediated by proteasomal degradation, which differs from inhibitory mechanisms for some neurotransmitter transporters under similar conditions. Increased oxidative-nitrosative stress in the microenvironment of cholinergic nerve terminals would diminish cholinergic transmission by reducing choline availability for ACh synthesis.
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36
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Sann SB, Crane MM, Lu H, Jin Y. Rabx-5 regulates RAB-5 early endosomal compartments and synaptic vesicles in C. elegans. PLoS One 2012; 7:e37930. [PMID: 22675499 PMCID: PMC3366993 DOI: 10.1371/journal.pone.0037930] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 04/30/2012] [Indexed: 01/25/2023] Open
Abstract
Early endosomal membrane compartments are required for the formation and recycling of synaptic vesicles, but how these compartments are regulated is incompletely understood. We performed a forward genetic screen in C. elegans for mutations that affect RAB-5 labeled early endosomal compartments in GABAergic motoneurons. Here we report the isolation and characterization of one mutation, rabx-5. The rabx-5 mutation leads to decreased intensity of YFP::RAB-5 in the cell soma but increased intensity in the synaptic and intersynaptic regions of the axon. This effect is due to the bias of the cycling state of RAB-5, and results from a change in the organization of the early endosomal compartment as well as the membrane binding state of RAB-5. Synaptic vesicle accumulation is altered in rabx-5 mutants, and synaptic transmission from cholinergic neurons is decreased. Early endosomal membrane compartments show disorganization with ageing and rabx-5 mutant animals age faster. These results suggest that rabx-5 regulation of RAB-5 compartments is important for maintaining proper synaptic function throughout the lifetime.
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Affiliation(s)
- Sharon B. Sann
- Neurobiology Section, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
- * E-mail: (SS); (YJ)
| | - Matthew M. Crane
- Interdisciplinary Program in Bioengineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Hang Lu
- Interdisciplinary Program in Bioengineering, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
- Howard Hughes Medical Institute University of California San Diego, La Jolla, California, United States of America
- * E-mail: (SS); (YJ)
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37
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Volknandt W, Karas M. Proteomic analysis of the presynaptic active zone. Exp Brain Res 2012; 217:449-61. [DOI: 10.1007/s00221-012-3031-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 02/04/2012] [Indexed: 02/06/2023]
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38
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Koudinova N, Koudinov A, Kezlya E, Kozirev K, Medvedev A, Berezov T. Compensatory mechanisms to heal neuroplasticity impairment under Alzheiemer's disease neurodegeneration. I: The role of amyloid beta and its' precursor protein. BIOMEDITSINSKAYA KHIMIYA 2012. [DOI: 10.18097/pbmc20125804385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In-depth scholar literature analysis of Alzheimer's disease neurodegenerative features of amyloid beta protein neurochemistry modification and excessive phosphorylation of tau protein (and associated neuronal cytoskeleton rearrangements) are secondary phenomena. At early disease stage these neurobiochemical mechanisms are reversible and serve to heal an impairment of biophysical properties of neuronal membranes, neurotransmission, basic neuronal function and neuroplasticity, while preserving anatomical and functional brain fields. Aβ and tau could well serve to biochemically restore physico-chemical properties of neual membranes due to a role these proteins play in lipid metabolism. Under such scenario therapeutic block of aggregation and plaque formation of Aβ and inhibition of tau phosphorylation, as well as pharmaceutical modification of other secondary neurodegenerative features (such as a cascade of oxidative stress reactions) are unable to provide an effective cure of Alzheimer's disease and related pathologies of the Central and peripheral nervous systems, because they are not arraying primary pathagenetic cause. We review the role of Aβ in compensatory mechanisms of neuroplasticity restoration under normal physiological condition and Alzheimer's disease.
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Affiliation(s)
| | - A.R. Koudinov
- Orekhovich Institute of Biomedical Chemistry of RAMS
| | - E.V. Kezlya
- Interhospital Medical Center "Intermedcenter"
| | - K.M. Kozirev
- Department of Pathological Anatomy, North Osetia State Medical Academy
| | - A.E. Medvedev
- Institute of Biomedical Chemistry, Russian Academy of Medical Sciences
| | - T.T. Berezov
- Orekhovich Institute of Biomedical Chemistry of RAMS Russian People`s Friendship University, Medical School, Department of Biochemistry
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39
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Abstract
Cholinergic neurons are endowed with a high-affinity choline uptake system for efficient synthesis of acetylcholine at the presynaptic terminals. The high-affinity choline transporter CHT1 is responsible for choline uptake, the rate-limiting step in acetylcholine synthesis. However, endogenous physiological factors that affect CHT1 expression or function and consequently regulate the acetylcholine synthesis rate are essentially unknown. Here we demonstrate that extracellular substrate decreases the cell-surface expression of CHT1 in rat brain synaptosomes, primary cultures from the basal forebrain, and mammalian cell lines transfected with CHT1. Extracellular choline rapidly decreases cell-surface CHT1 expression by accelerating its internalization, a process that is mediated by a dynamin-dependent endocytosis pathway in HEK293 cells. Specific inhibitor hemicholinium-3 decreases the constitutive internalization rate and thereby increases cell-surface CHT1 expression. We also demonstrate that the constitutive internalization of CHT1 depends on extracellular pH in cultured cells. Our results collectively suggest that the internalization of CHT1 is induced by extracellular substrate, providing a novel feedback mechanism for the regulation of acetylcholine synthesis at the cholinergic presynaptic terminals.
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40
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Zhang H, Ma Q, Zhang YW, Xu H. Proteolytic processing of Alzheimer's β-amyloid precursor protein. J Neurochem 2011; 120 Suppl 1:9-21. [PMID: 22122372 DOI: 10.1111/j.1471-4159.2011.07519.x] [Citation(s) in RCA: 231] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
β-Amyloid precursor protein (APP) is a critical factor in the pathogenesis of Alzheimer's disease (AD). APP undergoes post-translational proteolysis/processing to generate the hydrophobic β-amyloid (Aβ) peptides. Deposition of Aβ in the brain, forming oligomeric Aβ and plaques, is identified as one of the key pathological hallmarks of AD. The processing of APP to generate Aβ is executed by β- and γ-secretase and is highly regulated. Aβ toxicity can lead to synaptic dysfunction, neuronal cell death, impaired learning/memory and abnormal behaviors in AD models in vitro and in vivo. Aside from Aβ, proteolytic cleavages of APP can also give rise to the APP intracellular domain, reportedly involved in multiple types of cellular events such as gene transcription and apoptotic cell death. In addition to amyloidogenic processing, APP can also be cleaved by α-secretase to form a soluble or secreted APP ectodomain (sAPP-α) that has been shown to be mostly neuro-protective. In this review, we describe the mechanisms involved in APP metabolism and the likely functions of its various proteolytic products to give a better understanding of the patho/physiological functions of APP.
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Affiliation(s)
- Han Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, Fujian, China.,Neurodegenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
| | - Qilin Ma
- Department of Neurology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, China
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, Fujian, China
| | - Huaxi Xu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, Fujian, China.,Neurodegenerative Disease Research Program, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
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41
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Functional consequences of the lack of amyloid precursor protein in the mouse dentate gyrus in vivo. Exp Brain Res 2011; 217:441-7. [PMID: 22076403 DOI: 10.1007/s00221-011-2911-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 10/07/2011] [Indexed: 01/15/2023]
Abstract
The amyloid precursor protein (APP) plays a crucial role in the pathogenesis of Alzheimer's disease. Here, we studied whether the lack of APP affects the synaptic properties in the dentate gyrus by measuring granule cell field potentials evoked by perforant path stimulation in anesthetized 9-11-month-old APP-deficient mice in vivo. We found decreased paired-pulse facilitation, indicating altered presynaptic short-term plasticity in the APP-deficient dentate gyrus. In contrast, excitatory synaptic strength and granule cell firing were unchanged in APP knockout mice. Likewise, long-term potentiation (LTP) induced by a theta-burst stimulation protocol was not impaired in the absence of APP. These findings suggest that the deletion of APP may affect presynaptic plasticity of synaptic transmission at the perforant path-granule cell synapse but leaves synaptic efficacy intact and LTP preserved, possibly due to functional redundancy within the APP gene family.
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Aydin D, Weyer SW, Müller UC. Functions of the APP gene family in the nervous system: insights from mouse models. Exp Brain Res 2011; 217:423-34. [PMID: 21931985 DOI: 10.1007/s00221-011-2861-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 08/30/2011] [Indexed: 06/16/2024]
Abstract
The amyloid precursor protein (APP) plays a key role in the pathogenesis of Alzheimer's disease (AD), as proteolytical cleavage of APP gives rise to the β-amyloid peptide which is deposited in the brains of Alzheimer patients. During the past years, intense research efforts have been directed at elucidating the physiological function(s) of APP and the question of whether a perturbation of these functions contributes to AD pathogenesis. Indeed, a growing body of evidence has accumulated supporting a role of APP and the two closely related homologues APLP1 and APLP2 in various aspects of nervous system development and function, in particular, for synapse formation and function. This review summarizes recent insights into the in vivo role of the APP gene family from mice lacking individual or combinations of APP family members, with particular emphasis on recently generated knockin mice to examine the in vivo relevance of distinct functional domains.
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Affiliation(s)
- Dorothee Aydin
- Department of Bioinformatics and Functional Genomics, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany
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Zhou ZD, Chan CHS, Ma QH, Xu XH, Xiao ZC, Tan EK. The roles of amyloid precursor protein (APP) in neurogenesis: Implications to pathogenesis and therapy of Alzheimer disease. Cell Adh Migr 2011; 5:280-92. [PMID: 21785276 DOI: 10.4161/cam.5.4.16986] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The amyloid-beta (Aβ) peptide is the derivative of amyloid precursor protein (APP) generated through sequential proteolytic processing by β- and γ-secretases. Excessive accumulation of Aβ, the main constituent of amyloid plaques, has been implicated in the etiology of Alzheimer's disease (AD). It was found recently that the impairments of neurogenesis in brain were associated with the pathogenesis of AD. Furthermore recent findings implicated that APP could function to influence proliferation of neural progenitor cells (NPC) and might regulate transcriptional activity of various genes. Studies demonstrated that influence of neurogenesis by APP is conferred differently via its two separate domains, soluble secreted APPs (sAPPs, mainly sAPPα) and APP intracellular domain (AICD). The sAPPα was shown to be neuroprotective and important to neurogenesis, whereas AICD was found to negatively modulate neurogenesis. Furthermore, it was demonstrated recently that microRNA could function to regulate APP expression, APP processing, Aβ accumulation and subsequently influence neurotoxicity and neurogenesis related to APP, which was implicated to AD pathogenesis, especially for sporadic AD. Based on data accumulated, secretase balances were proposed. These secretase balances could influence the downstream balance related to regulation of neurogenesis by AICD and sAPPα as well as balance related to influence of neuron viability by Aβ and sAPPα. Disruption of these secretase balances could be culprits to AD onset.
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Ginsberg SD, Mufson EJ, Alldred MJ, Counts SE, Wuu J, Nixon RA, Che S. Upregulation of select rab GTPases in cholinergic basal forebrain neurons in mild cognitive impairment and Alzheimer's disease. J Chem Neuroanat 2011; 42:102-10. [PMID: 21669283 DOI: 10.1016/j.jchemneu.2011.05.012] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 05/26/2011] [Accepted: 05/26/2011] [Indexed: 02/02/2023]
Abstract
Endocytic system dysfunction is one of the earliest disturbances that occur in Alzheimer's disease (AD), and may underlie the selective vulnerability of cholinergic basal forebrain (CBF) neurons during the progression of dementia. Herein we report that genes regulating early and late endosomes are selectively upregulated within CBF neurons in mild cognitive impairment (MCI) and AD. Specifically, upregulation of rab4, rab5, rab7, and rab27 was observed in CBF neurons microdissected from postmortem brains of individuals with MCI and AD compared to age-matched control subjects with no cognitive impairment (NCI). Upregulated expression of rab4, rab5, rab7, and rab27 correlated with antemortem measures of cognitive decline in individuals with MCI and AD. qPCR validated upregulation of these select rab GTPases within microdissected samples of the basal forebrain. Moreover, quantitative immunoblot analysis demonstrated upregulation of rab5 protein expression in the basal forebrain of subjects with MCI and AD. The elevation of rab4, rab5, and rab7 expression is consistent with our recent observations in CA1 pyramidal neurons in MCI and AD. These findings provide further support that endosomal pathology accelerates endocytosis and endosome recycling, which may promote aberrant endosomal signaling and neurodegeneration throughout the progression of AD.
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Affiliation(s)
- Stephen D Ginsberg
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY 10962, USA.
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Zheng H, Koo EH. Biology and pathophysiology of the amyloid precursor protein. Mol Neurodegener 2011; 6:27. [PMID: 21527012 PMCID: PMC3098799 DOI: 10.1186/1750-1326-6-27] [Citation(s) in RCA: 215] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Accepted: 04/28/2011] [Indexed: 01/22/2023] Open
Abstract
The amyloid precursor protein (APP) plays a central role in the pathophysiology of Alzheimer's disease in large part due to the sequential proteolytic cleavages that result in the generation of β-amyloid peptides (Aβ). Not surprisingly, the biological properties of APP have also been the subject of great interest and intense investigations. Since our 2006 review, the body of literature on APP continues to expand, thereby offering further insights into the biochemical, cellular and functional properties of this interesting molecule. Sophisticated mouse models have been created to allow in vivo examination of cell type-specific functions of APP together with the many functional domains. This review provides an overview and update on our current understanding of the pathobiology of APP.
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Affiliation(s)
- Hui Zheng
- Huffington Center on Aging and Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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Correia SC, Santos RX, Perry G, Zhu X, Moreira PI, Smith MA. Insulin-resistant brain state: the culprit in sporadic Alzheimer's disease? Ageing Res Rev 2011; 10:264-73. [PMID: 21262392 DOI: 10.1016/j.arr.2011.01.001] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 01/11/2011] [Accepted: 01/14/2011] [Indexed: 01/03/2023]
Abstract
Severe abnormalities in brain glucose/energy metabolism and insulin signaling have been documented to take a pivotal role in early sporadic Alzheimer's disease (sAD) pathology. Indeed, the "insulin-resistant brain state" has been hypothesized to form the core of the neurodegenerative events that occur in sAD. In this vein, intracerebroventricular administration of subdiabetogenic doses of streptozotocin (STZ) in rats can induce an insulin-resistant brain state, which is proposed as a suitable experimental model of sAD. This review highlights the involvement of disturbed brain insulin metabolism in sAD etiopathogenesis. Furthermore, current knowledge demonstrates that central STZ administration produces brain pathology and behavioral changes that resemble changes found in sAD patients. The STZ-intracerebroventricularly treated rat represents a promising experimental tool in this field by providing new insights concerning early brain alterations in sAD, which can be translated in novel etiopathogenic and therapeutic approaches in this disease.
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Affiliation(s)
- Sónia C Correia
- Center for Neuroscience and Cell Biology of Coimbra, University of Coimbra, Portugal
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The intracellular threonine of amyloid precursor protein that is essential for docking of Pin1 is dispensable for developmental function. PLoS One 2011; 6:e18006. [PMID: 21445342 PMCID: PMC3062548 DOI: 10.1371/journal.pone.0018006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 02/17/2011] [Indexed: 12/11/2022] Open
Abstract
Background Processing of Aβ-precursor protein (APP) plays an important role in Alzheimer's Disease (AD) pathogenesis. Thr residue at amino acid 668 of the APP intracellular domain (AID) is highly conserved. When phosphorylated, this residue generates a binding site for Pin1. The interaction of APP with Pin1 has been involved in AD pathogenesis. Methodology/Principal Findings To dissect the functions of this sequence in vivo, we created an APP knock-in allele, in which Thr668 is replaced by an Ala (T668A). Doubly deficient APP/APP-like protein 2 (APLP2) mice present postnatal lethality and neuromuscular synapse defects. Previous work has shown that the APP intracellular domain is necessary for preventing early lethality and neuromuscular junctions (NMJ) defects. Crossing the T668A allele into the APLP2 knockout background showed that mutation of Thr668 does not cause a defective phenotype. Notably, the T668A mutant APP is able to bind Mint1. Conclusions/Significance Our results argue against an important role of the Thr668 residue in the essential function of APP in developmental regulation. Furthermore, they indicate that phosphorylation at this residue is not functionally involved in those APP-mediated functions that prevent (NMJ) defects and early lethality in APLP2 null mice.
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Ginsberg SD, Mufson EJ, Counts SE, Wuu J, Alldred MJ, Nixon RA, Che S. Regional selectivity of rab5 and rab7 protein upregulation in mild cognitive impairment and Alzheimer's disease. J Alzheimers Dis 2011; 22:631-9. [PMID: 20847427 DOI: 10.3233/jad-2010-101080] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Endocytic alterations are one of the earliest changes to occur in Alzheimer's disease (AD), and are hypothesized to be involved in the selective vulnerability of specific neuronal populations during the progression of AD. Previous microarray and real-time quantitative PCR experiments revealed an upregulation of the early endosomal effector rab5 and the late endosome constituent rab7 in the hippocampus of people with mild cognitive impairment (MCI) and AD. To assess whether these select rab GTPase gene expression changes are reflected in protein levels within selectively vulnerable brain regions (basal forebrain, frontal cortex, and hippocampus) and relatively spared areas (cerebellum and striatum), we performed immunoblot analysis using antibodies directed against rab5 and rab7 on postmortem human brain tissue harvested from cases with a premortem clinical diagnosis of no cognitive impairment (NCI), MCI, and AD. Results indicate selective upregulation of both rab5 and rab7 levels within basal forebrain, frontal cortex, and hippocampus in MCI and AD, which also correlated with Braak staging. In contrast, no differences in protein levels were found in the less vulnerable cerebellum and striatum. These regional immunoblot assays are consistent with single cell gene expression data, and provide protein-based evidence for endosomal markers contributing to the vulnerability of cell types within selective brain regions during the progression of AD.
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Affiliation(s)
- Stephen D Ginsberg
- Center for Dementia Research, Nathan Kline Institute, New York University Langone Medical Center, Orangeburg, NY 10962, USA.
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Dinet V, An N, Ciccotosto GD, Bruban J, Maoui A, Bellingham SA, Hill AF, Andersen OM, Nykjaer A, Jonet L, Cappai R, Mascarelli F. APP involvement in retinogenesis of mice. Acta Neuropathol 2011; 121:351-63. [PMID: 20978902 DOI: 10.1007/s00401-010-0762-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 10/11/2010] [Accepted: 10/14/2010] [Indexed: 12/23/2022]
Abstract
Very few studies have examined expression and function of amyloid precursor protein (APP) in the retina. We showed that APP mRNA and protein are expressed according to the different waves of retinal differentiation. Depletion of App led to an absence of amacrine cells, a 50% increase in the number of horizontal cells and alteration of the synapses. The retinas of adult APP(-/-) mice showed only half as many glycinergic amacrine cells as wild-type retinas. We identified Ptf1a, which plays a role in controlling both amacrine and horizontal cell fates, as a downstream effector of APP. The observation of a similar phenotype in sorLA knockout mice, a major regulator of APP processing, suggests that regulation of APP functions via sorLA controls the determination of amacrine and horizontal cell fate. These findings provide novel insights that indicate that APP plays an important role in retinal differentiation.
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Affiliation(s)
- Virginie Dinet
- Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris 6, INSERM, 15 rue de l'Ecole de Médecine, Paris, France
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Barbagallo APM, Wang Z, Zheng H, D'Adamio L. A single tyrosine residue in the amyloid precursor protein intracellular domain is essential for developmental function. J Biol Chem 2011; 286:8717-21. [PMID: 21266574 DOI: 10.1074/jbc.c111.219873] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The Aβ-precursor protein (APP) intracellular domain is highly conserved and contains many potentially important residues, in particular the (682)YENPTY(687) motif. To dissect the functions of this sequence in vivo, we created an APP knock-in allele mutating Tyr(682) to Gly (Y682G). Crossing this allele to APP-like protein 2 (APLP2) knock-out background showed that mutation of Tyr(682) results in postnatal lethality and neuromuscular synapse defects similar to doubly deficient APP/APLP2 mice. Our results demonstrate that a single residue in the APP intracellular region, Tyr(682), is indispensable for the essential function of APP in developmental regulation.
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Affiliation(s)
- Alessia P M Barbagallo
- Department of Microbiology and Immunology, Einstein College of Medicine, Bronx, New York 10461, USA
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