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Leighton PLA, Allison WT. Protein Misfolding in Prion and Prion-Like Diseases: Reconsidering a Required Role for Protein Loss-of-Function. J Alzheimers Dis 2018; 54:3-29. [PMID: 27392869 DOI: 10.3233/jad-160361] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Prion disease research has contributed much toward understanding other neurodegenerative diseases, including recent demonstrations that Alzheimer's disease (AD) and other neurodegenerative diseases are prion-like. Prion-like diseases involve the spread of degeneration between individuals and/or among cells or tissues via template directed misfolding, wherein misfolded protein conformers propagate disease by causing normal proteins to misfold. Here we use the premise that AD, amyotrophic lateral sclerosis, Huntington's disease, and other similar diseases are prion-like and ask: Can we apply knowledge gained from studies of these prion-like diseases to resolve debates about classical prion diseases? We focus on controversies about what role(s) protein loss-of-function might have in prion diseases because this has therapeutic implications, including for AD. We examine which loss-of-function events are recognizable in prion-like diseases by considering the normal functions of the proteins before their misfolding and aggregation. We then delineate scenarios wherein gain-of-function and/or loss-of-function would be necessary or sufficient for neurodegeneration. We consider roles of PrPC loss-of-function in prion diseases and in AD, and conclude that the conventional wisdom that prion diseases are 'toxic gain-of-function diseases' has limitations. While prion diseases certainly have required gain-of-function components, we propose that disease phenotypes are predominantly caused by deficits in the normal physiology of PrPC and its interaction partners as PrPC converts to PrPSc. In this model, gain-of-function serves mainly to spread disease, and loss-of-function directly mediates neuron dysfunction. We propose experiments and predictions to assess our conclusion. Further study on the normal physiological roles of these key proteins is warranted.
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Affiliation(s)
- Patricia L A Leighton
- Centre for Prions & Protein Folding Disease, University of Alberta, Edmonton, AB, Canada.,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - W Ted Allison
- Centre for Prions & Protein Folding Disease, University of Alberta, Edmonton, AB, Canada.,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
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Wong SY, Tang BL. SIRT1 as a therapeutic target for Alzheimer's disease. Rev Neurosci 2018; 27:813-825. [PMID: 27497424 DOI: 10.1515/revneuro-2016-0023] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 06/12/2016] [Indexed: 12/19/2022]
Abstract
Alzheimer's disease (AD) is the most prevalent cause of dementia in the aging population worldwide. SIRT1 deacetylation of histones and transcription factors impinge on multiple neuronal and non-neuronal targets, and modulates stress response, energy metabolism and cellular senescence/death pathways. Collectively, SIRT1 activity could potentially affect multiple aspects of hippocampal and cortical neuron function and survival, thus modifying disease onset and progression. In this review, the known and potential mechanisms of action of SIRT1 with regard to AD, and its potential as a therapeutic target, are discussed.
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53
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Mirza FJ, Zahid S. The Role of Synapsins in Neurological Disorders. Neurosci Bull 2017; 34:349-358. [PMID: 29282612 DOI: 10.1007/s12264-017-0201-7] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 10/27/2017] [Indexed: 12/12/2022] Open
Abstract
Synapsins serve as flagships among the presynaptic proteins due to their abundance on synaptic vesicles and contribution to synaptic communication. Several studies have emphasized the importance of this multi-gene family of neuron-specific phosphoproteins in maintaining brain physiology. In the recent times, increasing evidence has established the relevance of alterations in synapsins as a major determinant in many neurological disorders. Here, we give a comprehensive description of the diverse roles of the synapsin family and the underlying molecular mechanisms that contribute to several neurological disorders. These physiologically important roles of synapsins associated with neurological disorders are just beginning to be understood. A detailed understanding of the diversified expression of synapsins may serve to strategize novel therapeutic approaches for these debilitating neurological disorders.
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Affiliation(s)
- Fatima Javed Mirza
- Neurobiology Research Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan
| | - Saadia Zahid
- Neurobiology Research Laboratory, Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, Pakistan.
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54
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Human Brain-Derived Aβ Oligomers Bind to Synapses and Disrupt Synaptic Activity in a Manner That Requires APP. J Neurosci 2017; 37:11947-11966. [PMID: 29101243 DOI: 10.1523/jneurosci.2009-17.2017] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 09/19/2017] [Accepted: 09/29/2017] [Indexed: 12/20/2022] Open
Abstract
Compelling genetic evidence links the amyloid precursor protein (APP) to Alzheimer's disease (AD) and several theories have been advanced to explain the relationship. A leading hypothesis proposes that a small amphipathic fragment of APP, the amyloid β-protein (Aβ), self-associates to form soluble aggregates that impair synaptic and network activity. Here, we used the most disease-relevant form of Aβ, protein isolated from AD brain. Using this material, we show that the synaptotoxic effects of Aβ depend on expression of APP and that the Aβ-mediated impairment of synaptic plasticity is accompanied by presynaptic effects that disrupt the excitatory/inhibitory (E/I) balance. The net increase in the E/I ratio and inhibition of plasticity are associated with Aβ localizing to synapses and binding of soluble Aβ aggregates to synapses requires the expression of APP. Our findings indicate a role for APP in AD pathogenesis beyond the generation of Aβ and suggest modulation of APP expression as a therapy for AD.SIGNIFICANCE STATEMENT Here, we report on the plasticity-disrupting effects of amyloid β-protein (Aβ) isolated from Alzheimer's disease (AD) brain and the requirement of amyloid precursor protein (APP) for these effects. We show that Aβ-containing AD brain extracts block hippocampal LTP, augment glutamate release probability, and disrupt the excitatory/inhibitory balance. These effects are associated with Aβ localizing to synapses and genetic ablation of APP prevents both Aβ binding and Aβ-mediated synaptic dysfunctions. Our results emphasize the importance of APP in AD and should stimulate new studies to elucidate APP-related targets suitable for pharmacological manipulation.
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55
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56
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Duncan MJ, Smith JT, Franklin KM. Time of day but not aging regulates 5-HT 7 receptor binding sites in the hamster hippocampus. Neurosci Lett 2017; 662:306-311. [PMID: 29107707 DOI: 10.1016/j.neulet.2017.10.057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/18/2017] [Accepted: 10/27/2017] [Indexed: 12/15/2022]
Abstract
Activation of 5-HT7 receptors influences memory as well as circadian rhythms and other processes. This study investigated the regulation of the 5-HT7 receptors in the hippocampus, a likely substrate for the effects of 5-HT7 receptor compounds on memory. Because endogenous serotonin release is higher during the active phase, and chronic treatment with a serotonin-selective reuptake inhibitor down-regulates 5-HT7 receptors, we hypothesized that 5-HT7 receptors exhibit 24-h variations. We also hypothesized that aging decreases 5-HT7 receptors in the hippocampus, as it does in the dorsal raphe nucleus, a brain site for serotonergic resetting of circadian rhythms. Male hamsters (young, 3-5 mos; old, 17-21 mos) exposed to a light:dark cycle were euthanized at 4 times of day (zeitgeber times [ZT]1, 6, 13, & 19; ZT12=time of lights:off). 5-HT7 receptor autoradiography was conducted on hippocampal sections using [3H]8-OH-DPAT [2nM] as the radioligand and SB-269970 [1μM] to define nonspecific binding. Slide-mounted sections and radioactive standards were apposed to X-ray films; the resultant autoradiograms were assessed by computer-assisted microdensitometry. Specific 5-HT7 receptor binding was robustly expressed in the dentate gyrus (DG) and CA1 but not in the CA2 or CA3. In the CA1 and DG, specific 5-HT7 receptor binding exhibited 24-h rhythms with troughs at night (P<0.005; P<0.05, respectively). Aging did not significantly affect specific 5-HT7 receptor binding in these regions, nor were significant time and age interactions observed. These findings suggest that the therapeutic effectiveness of 5-HT7 drugs may vary with time of day of administration but not with the age of the recipient.
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Affiliation(s)
- Marilyn J Duncan
- Department of Neuroscience, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY 40536-0298, USA.
| | - J Tyler Smith
- Department of Neuroscience, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY 40536-0298, USA.
| | - Kathleen M Franklin
- Department of Neuroscience, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY 40536-0298, USA.
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57
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Liu A, Zhang Y, Han L, He G, Xie W, Zhou Z, Jia Z. Regulation of Neurotransmitter Release by Amyloid Precursor Protein Through Synapsin Phosphorylation. Neurochem Res 2017; 44:683-691. [PMID: 29052089 DOI: 10.1007/s11064-017-2418-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 10/01/2017] [Accepted: 10/09/2017] [Indexed: 12/19/2022]
Abstract
Abnormal processing of amyloid precursor protein (APP) and aggregation of the Aβ peptide are known to play a key role in the pathogenesis of Alzheimer disease, but the function of endogenous APP under normal physiological conditions remains poorly understood. In this study, we investigated presynaptic changes in APP knockout (KO) mice. We demonstrate that both sucrose-induced neurotransmission and synaptic depletion in response to high frequency stimulation are significantly enhanced in APP KO compared to wild type littermates. In addition, the level of phosphorylated forms of synapsins, but not total synapsins, is elevated in the KO mice. Furthermore, we show that the inhibition of L-type calcium channels normalizes phosphorylated synapsins and slows down the high frequency induced synaptic depletion in APP KO mice. These results suggest a new mechanism by which APP regulates synaptic vesicle dynamics through synapsin-dependent phosphorylation.
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Affiliation(s)
- An Liu
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Ying Zhang
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Lifang Han
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Guiqin He
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Wei Xie
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Zikai Zhou
- Institute of Life Sciences, The Key Laboratory of Developmental Genes and Human Disease, Jiangsu Co-innovation Center of Neuroregeneration, Southeast University, Nanjing, 210096, China
| | - Zhengping Jia
- Neurosciences & Mental Health, the Hospital for Sick Children, 555 University Ave., Toronto, ON, M5G 1X8, Canada. .,Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
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58
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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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59
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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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60
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Abstract
Amyloid-β (Aβ) deposition is one of the hallmarks of the amyloid hypothesis in Alzheimer’s disease (AD). Mouse models using APP-transgene overexpression to generate amyloid plaques have shown to model only certain parts of the disease. The extent to which the data from mice can be transferred to man remains controversial. Several studies have shown convincing treatment results in reducing Aβ and enhancing cognition in mice but failed totally in human. One model-dependent factor has so far been almost completely neglected: the endogenous expression of mouse APP and its effects on the transgenic models and the readout for therapeutic approaches. Here, we report that hAPP-transgenic models of amyloidosis devoid of endogenous mouse APP expression (mAPP-knockout / mAPPko) show increased amounts and higher speed of Aβ deposition than controls with mAPP. The number of senile plaques and the level of aggregated hAβ were elevated in mAPPko mice, while the deposition in cortical blood vessels was delayed, indicating an alteration in the general aggregation propensity of hAβ together with endogenous mAβ. Furthermore, the cellular response to Aβ deposition was modulated: mAPPko mice developed a pronounced and age-dependent astrogliosis, while microglial association to amyloid plaques was diminished. The expression of human and murine aggregation-prone proteins with differing amino acid sequences within the same mouse model might not only alter the extent of deposition but also modulate the route of pathogenesis, and thus, decisively influence the study outcome, especially in translational research.
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61
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Gannon PJ, Akay-Espinoza C, Yee AC, Briand LA, Erickson MA, Gelman BB, Gao Y, Haughey NJ, Zink MC, Clements JE, Kim NS, Van De Walle G, Jensen BK, Vassar R, Pierce RC, Gill AJ, Kolson DL, Diehl JA, Mankowski JL, Jordan-Sciutto KL. HIV Protease Inhibitors Alter Amyloid Precursor Protein Processing via β-Site Amyloid Precursor Protein Cleaving Enzyme-1 Translational Up-Regulation. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:91-109. [PMID: 27993242 DOI: 10.1016/j.ajpath.2016.09.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 08/22/2016] [Accepted: 09/12/2016] [Indexed: 12/14/2022]
Abstract
Mounting evidence implicates antiretroviral (ARV) drugs as potential contributors to the persistence and evolution of clinical and pathological presentation of HIV-associated neurocognitive disorders in the post-ARV era. Based on their ability to induce endoplasmic reticulum (ER) stress in various cell types, we hypothesized that ARV-mediated ER stress in the central nervous system resulted in chronic dysregulation of the unfolded protein response and altered amyloid precursor protein (APP) processing. We used in vitro and in vivo models to show that HIV protease inhibitor (PI) class ARVs induced neuronal damage and ER stress, leading to PKR-like ER kinase-dependent phosphorylation of the eukaryotic translation initiation factor 2α and enhanced translation of β-site APP cleaving enzyme-1 (BACE1). In addition, PIs induced β-amyloid production, indicative of increased BACE1-mediated APP processing, in rodent neuroglial cultures and human APP-expressing Chinese hamster ovary cells. Inhibition of BACE1 activity protected against neuronal damage. Finally, ARVs administered to mice and SIV-infected macaques resulted in neuronal damage and BACE1 up-regulation in the central nervous system. These findings implicate a subset of PIs as potential mediators of neurodegeneration in HIV-associated neurocognitive disorders.
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Affiliation(s)
- Patrick J Gannon
- Department of Pharmacology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Cagla Akay-Espinoza
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Alan C Yee
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Lisa A Briand
- Department of Psychology, Temple University, Philadelphia, Pennsylvania
| | - Michelle A Erickson
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Benjamin B Gelman
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas
| | - Yan Gao
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina
| | - Norman J Haughey
- Richard T. Johnson Division of Neuroimmunology and Neurological Infections, Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - M Christine Zink
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Janice E Clements
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nicholas S Kim
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Gabriel Van De Walle
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Brigid K Jensen
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Robert Vassar
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - R Christopher Pierce
- Department of Psychiatry, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Alexander J Gill
- Department of Neurology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Dennis L Kolson
- Department of Neurology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - J Alan Diehl
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina
| | - Joseph L Mankowski
- Richard T. Johnson Division of Neuroimmunology and Neurological Infections, Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Kelly L Jordan-Sciutto
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
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Montagna E, Dorostkar MM, Herms J. The Role of APP in Structural Spine Plasticity. Front Mol Neurosci 2017; 10:136. [PMID: 28539872 PMCID: PMC5423954 DOI: 10.3389/fnmol.2017.00136] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/21/2017] [Indexed: 11/15/2022] Open
Abstract
Amyloid precursor protein (APP) is a transmembrane protein highly expressed in neurons. The full-length protein has cell-adhesion and receptor-like properties, which play roles in synapse formation and stability. Furthermore, APP can be cleaved by several proteases into numerous fragments, many of which affect synaptic function and stability. This review article focuses on the mechanisms of APP in structural spine plasticity, which encompasses the morphological alterations at excitatory synapses. These occur as changes in the number and morphology of dendritic spines, which correspond to the postsynaptic compartment of excitatory synapses. Both overexpression and knockout (KO) of APP lead to impaired synaptic plasticity. Recent data also suggest a role of APP in the regulation of astrocytic D-serine homeostasis, which in turn regulates synaptic plasticity.
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Affiliation(s)
- Elena Montagna
- Department for Translational Brain Research, German Center for Neurodegenerative Diseases (DZNE), Ludwig-Maximilian-University MunichMunich, Germany
| | - Mario M Dorostkar
- Center for Neuropathology and Prion Research, Ludwig-Maximilian-University MunichMunich, Germany
| | - Jochen Herms
- Department for Translational Brain Research, German Center for Neurodegenerative Diseases (DZNE), Ludwig-Maximilian-University MunichMunich, Germany.,Center for Neuropathology and Prion Research, Ludwig-Maximilian-University MunichMunich, Germany.,Munich Cluster of Systems Neurology (SyNergy), Ludwig-Maximilian-University MunichMunich, Germany
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63
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Isoflurane anesthesia promotes cognitive impairment by inducing expression of β-amyloid protein-related factors in the hippocampus of aged rats. PLoS One 2017; 12:e0175654. [PMID: 28403230 PMCID: PMC5389819 DOI: 10.1371/journal.pone.0175654] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 03/29/2017] [Indexed: 11/21/2022] Open
Abstract
Isoflurane anesthesia has been shown to be responsible for cognitive impairment in Alzheimer’s disease (AD) and development of AD in the older age groups. However, the pathogenesis of AD-related cognitive impairments induced by isoflurane anesthesia remains elusive. Thus, this study was designed to investigate the mechanism by which isoflurane anesthesia caused AD-related cognitive impairments. Aged Wistar rats were randomly divided into 6 groups (n = 12), 1 control group (CONT) and 5 isoflurane treated (ISO) groups (ISO 0, ISO 0.5D, ISO 1D, ISO 3D and ISO 7D). The CONT group inhaled 30% O2 for 2 h without any anesthesia. ISO groups were placed under anesthesia with 3% isoflurane and then exposed to 1.5% isoflurane delivered in 30% O2 for 2 h. Rats in each ISO group were then analyzed immediately (ISO 0) or at various time points (0.5, 1, 3 or 7 day) after this exposure. Cognitive function was assessed using the Morris water maze test. Protein levels of amyloid precursor protein (APP), β-site APP cleavage enzyme-1 (BACE-1) and Aβ42 peptide were analyzed in hippocampal samples by Western blot. β-Amyloid (Abeta) plaques were detected in hippocampal sections by Congo red staining. Compared with controls, all ISO groups showed increased escape latency and impaired spatial memory. Isoflurane increased APP mRNA expression and APP protein depletion, promoting Aβ42 overproduction, oligomerization and accumulation. However, isoflurane did not affect BACE-1 expression. Abeta plaques were observed only in those ISO groups sacrificed at 3 or 7 d. Our data indicate that aged rats exposed to isoflurane had increased APP mRNA expression and APP protein depletion, with Aβ42 peptide overproduction and oligomerization, resulting in formation of Abeta plaques in the hippocampus. Such effects might have contributed to cognitive impairments, including in spatial memory, observed in these rats after isoflurane anesthesia.
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Vanden Dries V, Stygelbout V, Pierrot N, Yilmaz Z, Suain V, De Decker R, Buée L, Octave JN, Brion JP, Leroy K. Amyloid precursor protein reduction enhances the formation of neurofibrillary tangles in a mutant tau transgenic mouse model. Neurobiol Aging 2017; 55:202-212. [PMID: 28464981 DOI: 10.1016/j.neurobiolaging.2017.03.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 02/01/2017] [Accepted: 03/28/2017] [Indexed: 11/30/2022]
Abstract
Alzheimer's disease is characterized by the presence of 2 neuropathological lesions: neurofibrillary tangles, composed of tau proteins which are highly phosphorylated and phosphorylated on uncommon sites, and amyloid plaques, containing the Aß peptides generated from the amyloid precursor protein (APP). Reduction of some APP proteolytic derivatives in Alzheimer's disease such as sAPPα fragment has been reported and sAPPα has been shown to affect tau phosphorylation. To investigate in vivo the effect of absence of APP protein and its fragments on tau phosphorylation and the formation of neurofibrillary tangles, we have generated mice deleted for APP gene and overexpressing a human mutant tau protein and developing neurofibrillary tangles (APPKOTg30 mice). These APPKOTg30 mice showed more severe motor and cognitive deficits, increased tau phosphorylation, increased load of neurofibrillary tangles, and increased p25/35 ratio in the brain, compared with Tg30 mice. These data suggest that APP and/or its proteolytic derivatives interfere with the formation of neurofibrillary tangles in a transgenic mouse model that will be useful for investigating the relationship between APP and tau.
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Affiliation(s)
- Virginie Vanden Dries
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculty of Medicine, Université Libre de Bruxelles, ULB Neuroscience Institute, Brussels, Belgium
| | - Virginie Stygelbout
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculty of Medicine, Université Libre de Bruxelles, ULB Neuroscience Institute, Brussels, Belgium
| | - Nathalie Pierrot
- Institute of Neurosciences, Université catholique de Louvain, Brussels, Belgium
| | - Zehra Yilmaz
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculty of Medicine, Université Libre de Bruxelles, ULB Neuroscience Institute, Brussels, Belgium
| | - Valérie Suain
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculty of Medicine, Université Libre de Bruxelles, ULB Neuroscience Institute, Brussels, Belgium
| | - Robert De Decker
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculty of Medicine, Université Libre de Bruxelles, ULB Neuroscience Institute, Brussels, Belgium
| | - Luc Buée
- Universite de Lille, INSERM, CHU-Lille, UMR-S 1172, LabEx DISTALZ, Lille, France
| | - Jean-Noël Octave
- Institute of Neurosciences, Université catholique de Louvain, Brussels, Belgium
| | - Jean-Pierre Brion
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculty of Medicine, Université Libre de Bruxelles, ULB Neuroscience Institute, Brussels, Belgium
| | - Karelle Leroy
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculty of Medicine, Université Libre de Bruxelles, ULB Neuroscience Institute, Brussels, Belgium.
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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: 371] [Impact Index Per Article: 53.0] [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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Guénette S, Strecker P, Kins S. APP Protein Family Signaling at the Synapse: Insights from Intracellular APP-Binding Proteins. Front Mol Neurosci 2017; 10:87. [PMID: 28424586 PMCID: PMC5371672 DOI: 10.3389/fnmol.2017.00087] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 03/13/2017] [Indexed: 12/17/2022] Open
Abstract
Understanding the molecular mechanisms underlying amyloid precursor protein family (APP/APP-like proteins, APLP) function in the nervous system can be achieved by studying the APP/APLP interactome. In this review article, we focused on intracellular APP interacting proteins that bind the YENPTY internalization motif located in the last 15 amino acids of the C-terminal region. These proteins, which include X11/Munc-18-interacting proteins (Mints) and FE65/FE65Ls, represent APP cytosolic binding partners exhibiting different neuronal functions. A comparison of FE65 and APP family member mutant mice revealed a shared function for APP/FE65 protein family members in neurogenesis and neuronal positioning. Accumulating evidence also supports a role for membrane-associated APP/APLP proteins in synapse formation and function. Therefore, it is tempting to speculate that APP/APLP C-terminal interacting proteins transmit APP/APLP-dependent signals at the synapse. Herein, we compare our current knowledge of the synaptic phenotypes of APP/APLP mutant mice with those of mice lacking different APP/APLP interaction partners and discuss the possible downstream effects of APP-dependent FE65/FE65L or X11/Mint signaling on synaptic vesicle release, synaptic morphology and function. Given that the role of X11/Mint proteins at the synapse is well-established, we propose a model highlighting the role of FE65 protein family members for transduction of APP/APLP physiological function at the synapse.
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Affiliation(s)
| | - Paul Strecker
- Department of Biology, Division of Human Biology, University of KaiserslauternKaiserslautern, Germany
| | - Stefan Kins
- Department of Biology, Division of Human Biology, University of KaiserslauternKaiserslautern, Germany
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Doshina A, Gourgue F, Onizuka M, Opsomer R, Wang P, Ando K, Tasiaux B, Dewachter I, Kienlen-Campard P, Brion JP, Gailly P, Octave JN, Pierrot N. Cortical cells reveal APP as a new player in the regulation of GABAergic neurotransmission. Sci Rep 2017; 7:370. [PMID: 28337033 PMCID: PMC5428293 DOI: 10.1038/s41598-017-00325-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 02/21/2017] [Indexed: 12/30/2022] Open
Abstract
The amyloid precursor protein (APP) modulates synaptic activity, resulting from the fine tuning of excitatory and inhibitory neurotransmission. GABAergic inhibitory neurotransmission is affected by modifications in intracellular chloride concentrations regulated by Na+-K+-2Cl- cotransporter 1 (NKCC1) and neuronal K+-Cl- cotransporter 2 (KCC2), allowing entrance and efflux of chloride, respectively. Modifications in NKCC1 and KCC2 expression during maturation of cortical cells induce a shift in GABAergic signaling. Here, we demonstrated that APP affects this GABA shift. Expression of APP in cortical cells decreased the expression of KCC2, without modifying NKCC1, eliciting a less inhibitory GABA response. Downregulation of KCC2 expression by APP was independent of the APP intracellular domain, but correlated with decreased expression of upstream stimulating factor 1 (USF1), a potent regulator of Slc12a5 gene expression (encoding KCC2). KCC2 was also downregulated in vivo following APP expression in neonatal mouse brain. These results argue for a key role of APP in the regulation of GABAergic neurotransmission.
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Affiliation(s)
- Anna Doshina
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium
| | - Florian Gourgue
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium
| | - Michiho Onizuka
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium
| | - Remi Opsomer
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium
| | - Peng Wang
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium
| | - Kunie Ando
- Laboratory of Histology and Neuropathology, Université libre de Bruxelles, 1070, Brussels, Belgium
| | - Bernadette Tasiaux
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium
| | - Ilse Dewachter
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium
| | | | - Jean-Pierre Brion
- Laboratory of Histology and Neuropathology, Université libre de Bruxelles, 1070, Brussels, Belgium
| | - Philippe Gailly
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium
| | - Jean-Noël Octave
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium.
| | - Nathalie Pierrot
- Institute of Neuroscience, Université catholique de Louvain, 1200, Brussels, Belgium
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68
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Amyloid Precursor Protein in Drosophila Glia Regulates Sleep and Genes Involved in Glutamate Recycling. J Neurosci 2017; 37:4289-4300. [PMID: 28314820 DOI: 10.1523/jneurosci.2826-16.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 02/03/2017] [Accepted: 02/27/2017] [Indexed: 12/19/2022] Open
Abstract
Amyloid precursor protein (App) plays a crucial role in Alzheimer's disease via the production and deposition of toxic β-amyloid peptides. App is heavily expressed in neurons, the focus of the vast majority of studies investigating its function. Meanwhile, almost nothing is known about App's function in glia, where it is also expressed, and can potentially participate in the regulation of neuronal physiology. In this report, we investigated whether Appl, the Drosophila homolog of App, could influence sleep-wake regulation when its function is manipulated in glial cells. Appl inhibition in astrocyte-like and cortex glia resulted in higher sleep amounts and longer sleep bout duration during the night, while overexpression had the opposite effect. These sleep phenotypes were not the result of developmental defects, and were correlated with changes in expression in glutamine synthetase (GS) in astrocyte-like glia and in changes in the gap-junction component innexin2 in cortex glia. Downregulating both GS and innexin2, but not either one individually, resulted in higher sleep amounts, similarly to Appl inhibition. Consistent with these results, the expression of GS and innexin2 are increased following sleep deprivation, indicating that GS and innexin2 genes are dynamically linked to vigilance states. Interestingly, the reduction of GS expression and the sleep phenotype observed upon Appl inhibition could be rescued by increasing the expression of the glutamate transporter dEaat1. In contrast, reducing dEaat1 expression severely disrupted sleep. These results associate glutamate recycling, sleep, and a glial function for the App family proteins.SIGNIFICANCE STATEMENT The amyloid precursor protein (App) has been intensively studied for its implication in Alzheimer's disease (AD). The attributed functions of App are linked to the physiology and cellular biology of neurons where the protein is predominantly expressed. Consequences on glia in AD are generally thought to be secondary effects of the pathology in neurons. Researchers still do not know whether App plays a role in glia in nonpathological conditions. We report here that glial App plays a role in physiology and in the regulation of sleep/wake, which has been shown recently to be involved in AD pathology. These results also associate glutamate recycling and sleep regulation, adding further complexity to the physiological role of App and to its implication in AD.
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Abstract
PURPOSE OF REVIEW Non-invasive neuroimaging methods have been developed as powerful tools for identifying in vivo brain functions for studies in humans and animals. Here we review the imaging biomarkers that are being used to determine the changes within brain metabolic and vascular functions induced by caloric restriction (CR), and their potential usefulness for future studies with dietary interventions in humans. RECENT FINDINGS CR causes an early shift in brain metabolism of glucose to ketone bodies, and enhances ATP production, neuronal activity and cerebral blood flow (CBF). With age, CR preserves mitochondrial activity, neurotransmission, CBF, and spatial memory. CR also reduces anxiety in aging mice. Neuroimaging studies in humans show that CR restores abnormal brain activity in the amygdala of women with obesity and enhances brain connectivity in old adults. SUMMARY Neuroimaging methods have excellent translational values and can be widely applied in future studies to identify dietary effects on brain functions in humans.
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Mockett BG, Richter M, Abraham WC, Müller UC. Therapeutic Potential of Secreted Amyloid Precursor Protein APPsα. Front Mol Neurosci 2017; 10:30. [PMID: 28223920 PMCID: PMC5293819 DOI: 10.3389/fnmol.2017.00030] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 01/25/2017] [Indexed: 11/26/2022] Open
Abstract
Cleavage of the amyloid precursor protein (APP) by α-secretase generates an extracellularly released fragment termed secreted APP-alpha (APPsα). Not only is this process of interest due to the cleavage of APP within the amyloid-beta sequence, but APPsα itself has many physiological properties that suggest its great potential as a therapeutic target. For example, APPsα is neurotrophic, neuroprotective, neurogenic, a stimulator of protein synthesis and gene expression, and enhances long-term potentiation (LTP) and memory. While most early studies have been conducted in vitro, effectiveness in animal models is now being confirmed. These studies have revealed that either upregulating α-secretase activity, acutely administering APPsα or chronic delivery of APPsα via a gene therapy approach can effectively treat mouse models of Alzheimer's disease (AD) and other disorders such as traumatic head injury. Together these findings suggest the need for intensifying research efforts to harness the therapeutic potential of this multifunctional protein.
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Affiliation(s)
- Bruce G. Mockett
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of OtagoOtago, New Zealand
| | - Max Richter
- Department of Functional Genomics, Institute for Pharmacy and Molecular Biotechnology, Heidelberg UniversityHeidelberg, Germany
| | - Wickliffe C. Abraham
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of OtagoOtago, New Zealand
| | - Ulrike C. Müller
- Department of Functional Genomics, Institute for Pharmacy and Molecular Biotechnology, Heidelberg UniversityHeidelberg, Germany
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71
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Laßek M, Weingarten J, Wegner M, Neupärtl M, Array TN, Harde E, Beckert B, Golghalyani V, Ackermann J, Koch I, Müller UC, Karas M, Acker-Palmer A, Volknandt W. APP Deletion Accounts for Age-Dependent Changes in the Bioenergetic Metabolism and in Hyperphosphorylated CaMKII at Stimulated Hippocampal Presynaptic Active Zones. Front Synaptic Neurosci 2017; 9:1. [PMID: 28163681 PMCID: PMC5247443 DOI: 10.3389/fnsyn.2017.00001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/05/2017] [Indexed: 11/13/2022] Open
Abstract
Synaptic release sites are characterized by exocytosis-competent synaptic vesicles tightly anchored to the presynaptic active zone (PAZ) whose proteome orchestrates the fast signaling events involved in synaptic vesicle cycle and plasticity. Allocation of the amyloid precursor protein (APP) to the PAZ proteome implicated a functional impact of APP in neuronal communication. In this study, we combined state-of-the-art proteomics, electrophysiology and bioinformatics to address protein abundance and functional changes at the native hippocampal PAZ in young and old APP-KO mice. We evaluated if APP deletion has an impact on the metabolic activity of presynaptic mitochondria. Furthermore, we quantified differences in the phosphorylation status after long-term-potentiation (LTP) induction at the purified native PAZ. We observed an increase in the phosphorylation of the signaling enzyme calmodulin-dependent kinase II (CaMKII) only in old APP-KO mice. During aging APP deletion is accompanied by a severe decrease in metabolic activity and hyperphosphorylation of CaMKII. This attributes an essential functional role to APP at hippocampal PAZ and putative molecular mechanisms underlying the age-dependent impairments in learning and memory in APP-KO mice.
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Affiliation(s)
- Melanie Laßek
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Jens Weingarten
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Martin Wegner
- Molecular Bioinformatics, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Moritz Neupärtl
- Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | | | - Eva Harde
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-UniversitätFrankfurt, Germany; Max Planck Institute for Brain ResearchFrankfurt, Germany
| | - Benedikt Beckert
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Vahid Golghalyani
- Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Jörg Ackermann
- Molecular Bioinformatics, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Ina Koch
- Molecular Bioinformatics, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Ulrike C Müller
- Department of Pharmacy and Molecular Biotechnology, University Heidelberg Heidelberg, Germany
| | - Michael Karas
- Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe-Universität Frankfurt, Germany
| | - Amparo Acker-Palmer
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-UniversitätFrankfurt, Germany; Max Planck Institute for Brain ResearchFrankfurt, Germany
| | - Walter Volknandt
- Institute for Cell Biology and Neuroscience, Biologicum and BMLS, Johann Wolfgang Goethe-Universität Frankfurt, Germany
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Ricciarelli R, Fedele E. The Amyloid Cascade Hypothesis in Alzheimer's Disease: It's Time to Change Our Mind. Curr Neuropharmacol 2017; 15:926-935. [PMID: 28093977 PMCID: PMC5652035 DOI: 10.2174/1570159x15666170116143743] [Citation(s) in RCA: 214] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 01/04/2017] [Accepted: 01/14/2017] [Indexed: 01/18/2023] Open
Abstract
Since its discovery in 1984, the beta amyloid peptide has treaded the boards of neurosciences as the star molecule in Alzheimer's disease pathogenesis. In the last decade, however, this vision has been challenged by evidence-based medicine showing the almost complete failure of clinical trials that experimented anti-amyloid therapies with great hopes. Moreover, data have accumulated which clearly indicate that this small peptide plays a key role in the physiological processes of memory formation. In the present review, we will discuss the different aspects of the amyloid cascade hypothesis, highlighting its pros and cons, and we will analyse the results of the therapeutic approaches attempted to date that should change the direction of Alzheimer's disease research in the future.
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Affiliation(s)
- Roberta Ricciarelli
- Department of Experimental Medicine, Section of General Pathology, University of Genova, Genova, Italy
| | - Ernesto Fedele
- Department of Pharmacy, Section of Pharmacology and Toxicology, University of Genova, Genova, Italy
- Center of Excellence for Biomedical Research, University of Genova, Genova, Italy
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73
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Canter RG, Penney J, Tsai LH. The road to restoring neural circuits for the treatment of Alzheimer's disease. Nature 2016; 539:187-196. [PMID: 27830780 DOI: 10.1038/nature20412] [Citation(s) in RCA: 360] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Accepted: 08/03/2016] [Indexed: 01/01/2023]
Abstract
Alzheimer's disease is a progressive loss of memory and cognition, for which there is no cure. Although genetic studies initially suggested a primary role for amyloid-in Alzheimer's disease, treatment strategies targeted at reducing amyloid-have failed to reverse cognitive symptoms. These clinical findings suggest that cognitive decline is the result of a complex pathophysiology and that targeting amyloid-alone may not be sufficient to treat Alzheimer's disease. Instead, a broad outlook on neural-circuit-damaging processes may yield insights into new therapeutic strategies for curing memory loss in the disease.
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Affiliation(s)
- Rebecca G Canter
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jay Penney
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Li-Huei Tsai
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.,The Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
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74
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Del Turco D, Paul MH, Schlaudraff J, Hick M, Endres K, Müller UC, Deller T. Region-Specific Differences in Amyloid Precursor Protein Expression in the Mouse Hippocampus. Front Mol Neurosci 2016; 9:134. [PMID: 27965537 PMCID: PMC5126089 DOI: 10.3389/fnmol.2016.00134] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/15/2016] [Indexed: 12/20/2022] Open
Abstract
The physiological role of amyloid precursor protein (APP) has been extensively investigated in the rodent hippocampus. Evidence suggests that APP plays a role in synaptic plasticity, dendritic and spine morphogenesis, neuroprotection and—at the behavioral level—hippocampus-dependent forms of learning and memory. Intriguingly, however, studies focusing on the role of APP in synaptic plasticity have reported diverging results and considerable differences in effect size between the dentate gyrus (DG) and area CA1 of the mouse hippocampus. We speculated that regional differences in APP expression could underlie these discrepancies and studied the expression of APP in both regions using immunostaining, in situ hybridization (ISH), and laser microdissection (LMD) in combination with quantitative reverse transcription polymerase chain reaction (RT-qPCR) and western blotting. In sum, our results show that APP is approximately 1.7-fold higher expressed in pyramidal cells of Ammon’s horn than in granule cells of the DG. This regional difference in APP expression may explain why loss-of-function approaches using APP-deficient mice revealed a role for APP in Hebbian plasticity in area CA1, whereas this could not be shown in the DG of the same APP mutants.
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Affiliation(s)
- Domenico Del Turco
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Germany
| | - Mandy H Paul
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Germany
| | - Jessica Schlaudraff
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Germany
| | - Meike Hick
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-UniversityFrankfurt, Germany; Institute of Pharmacy and Molecular Biotechnology (IPMB), Heidelberg UniversityHeidelberg, Germany
| | - Kristina Endres
- Clinic for Psychiatry and Psychotherapy, University Medical Center Mainz Mainz, Germany
| | - Ulrike C Müller
- Institute of Pharmacy and Molecular Biotechnology (IPMB), Heidelberg University Heidelberg, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University Frankfurt, Germany
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75
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Del Prete D, Rice RC, Rajadhyaksha AM, D'Adamio L. Amyloid Precursor Protein (APP) May Act as a Substrate and a Recognition Unit for CRL4CRBN and Stub1 E3 Ligases Facilitating Ubiquitination of Proteins Involved in Presynaptic Functions and Neurodegeneration. J Biol Chem 2016; 291:17209-27. [PMID: 27325702 DOI: 10.1074/jbc.m116.733626] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Indexed: 12/23/2022] Open
Abstract
The amyloid precursor protein (APP), whose mutations cause Alzheimer disease, plays an important in vivo role and facilitates transmitter release. Because the APP cytosolic region (ACR) is essential for these functions, we have characterized its brain interactome. We found that the ACR interacts with proteins that regulate the ubiquitin-proteasome system, predominantly with the E3 ubiquitin-protein ligases Stub1, which binds the NH2 terminus of the ACR, and CRL4(CRBN), which is formed by Cul4a/b, Ddb1, and Crbn, and interacts with the COOH terminus of the ACR via Crbn. APP shares essential functions with APP-like protein-2 (APLP2) but not APP-like protein-1 (APLP1). Noteworthy, APLP2, but not APLP1, interacts with Stub1 and CRL4(CRBN), pointing to a functional pathway shared only by APP and APLP2. In vitro ubiquitination/ubiquitome analysis indicates that these E3 ligases are enzymatically active and ubiquitinate the ACR residues Lys(649/650/651/676/688) Deletion of Crbn reduces ubiquitination of Lys(676) suggesting that Lys(676) is physiologically ubiquitinated by CRL4(CRBN) The ACR facilitated in vitro ubiquitination of presynaptic proteins that regulate exocytosis, suggesting a mechanism by which APP tunes transmitter release. Other dementia-related proteins, namely Tau and apoE, interact with and are ubiquitinated via the ACR in vitro This, and the evidence that CRBN and CUL4B are linked to intellectual disability, prompts us to hypothesize a pathogenic mechanism, in which APP acts as a modulator of E3 ubiquitin-protein ligase(s), shared by distinct neuronal disorders. The well described accumulation of ubiquitinated protein inclusions in neurodegenerative diseases and the link between the ubiquitin-proteasome system and neurodegeneration make this concept plausible.
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Affiliation(s)
- Dolores Del Prete
- From the Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461 and
| | - Richard C Rice
- the Division of Pediatric Neurology, Department of Pediatrics, and
| | - Anjali M Rajadhyaksha
- the Division of Pediatric Neurology, Department of Pediatrics, and Feil Family Brain and Mind Research Institute, Weill Cornell Autism Research Program, Weill Cornell Medical College, New York, New York 10065
| | - Luciano D'Adamio
- From the Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461 and
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Kepp KP. Alzheimer's disease due to loss of function: A new synthesis of the available data. Prog Neurobiol 2016; 143:36-60. [PMID: 27327400 DOI: 10.1016/j.pneurobio.2016.06.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 06/10/2016] [Accepted: 06/11/2016] [Indexed: 12/11/2022]
Abstract
Alzheimer's Disease (AD) is a highly complex disease involving a broad range of clinical, cellular, and biochemical manifestations that are currently not understood in combination. This has led to many views of AD, e.g. the amyloid, tau, presenilin, oxidative stress, and metal hypotheses. The amyloid hypothesis has dominated the field with its assumption that buildup of pathogenic β-amyloid (Aβ) peptide causes disease. This paradigm has been criticized, yet most data suggest that Aβ plays a key role in the disease. Here, a new loss-of-function hypothesis is synthesized that accounts for the anomalies of the amyloid hypothesis, e.g. the curious pathogenicity of the Aβ42/Aβ40 ratio, the loss of Aβ caused by presenilin mutation, the mixed phenotypes of APP mutations, the poor clinical-biochemical correlations for genetic variant carriers, and the failure of Aβ reducing drugs. The amyloid-loss view accounts for recent findings on the structure and chemical features of Aβ variants and their coupling to human patient data. The lost normal function of APP/Aβ is argued to be metal transport across neuronal membranes, a view with no apparent anomalies and substantially more explanatory power than the gain-of-function amyloid hypothesis. In the loss-of-function scenario, the central event of Aβ aggregation is interpreted as a loss of soluble, functional monomer Aβ rather than toxic overload of oligomers. Accordingly, new research models and treatment strategies should focus on remediation of the functional amyloid balance, rather than strict containment of Aβ, which, for reasons rationalized in this review, has failed clinically.
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Affiliation(s)
- Kasper P Kepp
- Technical University of Denmark, DTU Chemistry, DK-2800 Kongens Lyngby, Denmark.
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77
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Ohno M. Alzheimer's therapy targeting the β-secretase enzyme BACE1: Benefits and potential limitations from the perspective of animal model studies. Brain Res Bull 2016; 126:183-198. [PMID: 27093940 DOI: 10.1016/j.brainresbull.2016.04.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/05/2016] [Accepted: 04/10/2016] [Indexed: 01/18/2023]
Abstract
Accumulating evidence points to the amyloid-β (Aβ) peptide as the culprit in the pathogenesis of Alzheimer's disease (AD). β-Site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) is a protease that is responsible for initiating Aβ production. Although precise mechanisms that trigger Aβ accumulation remain unclear, BACE1 inhibition undoubtedly represents an important intervention that may prevent and/or cure AD. Remarkably, animal model studies with knockouts, virus-delivered small interfering RNAs, immunization and bioavailable small-molecule agents that specifically inhibit BACE1 activity strongly support the idea for the therapeutic BACE1 inhibition. Meanwhile, a growing number of BACE1 substrates besides APP uncover new physiological roles of this protease, raising some concern regarding the safety of BACE1 inhibition. Here, I review recent progress in preclinical studies that have evaluated the efficacies and potential limitations of genetic/pharmacological inhibition of BACE1, with special focus on AD-associated phenotypes including synaptic dysfunction, neuron loss and memory deficits in animal models.
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Affiliation(s)
- Masuo Ohno
- Center for Dementia Research, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA; Departments of Psychiatry, New York University Langone Medical Center, New York, NY 10016, USA.
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78
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Plummer S, Van den Heuvel C, Thornton E, Corrigan F, Cappai R. The Neuroprotective Properties of the Amyloid Precursor Protein Following Traumatic Brain Injury. Aging Dis 2016; 7:163-79. [PMID: 27114849 PMCID: PMC4809608 DOI: 10.14336/ad.2015.0907] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 09/07/2015] [Indexed: 01/16/2023] Open
Abstract
Despite the significant health and economic burden that traumatic brain injury (TBI) places on society, the development of successful therapeutic agents have to date not translated into efficacious therapies in human clinical trials. Injury to the brain is ongoing after TBI, through a complex cascade of primary and secondary injury events, providing a valuable window of opportunity to help limit and prevent some of the severe consequences with a timely treatment. Of note, it has been suggested that novel treatments for TBI should be multifactorial in nature, mimicking the body's own endogenous repair response. Whilst research has historically focused on the role of the amyloid precursor protein (APP) in the pathogenesis of Alzheimer's disease, recent advances in trauma research have demonstrated that APP offers considerable neuroprotective properties following TBI, suggesting that APP is an ideal therapeutic candidate. Its acute upregulation following TBI has been shown to serve a beneficial role following trauma and has lead to significant advances in understanding the neuroprotective and neurotrophic functions of APP and its metabolites. Research has focused predominantly on the APP derivative sAPPα, which has consistently demonstrated neuroprotective and neurotrophic functions both in vitro and in vivo following various traumatic insults. Its neuroprotective activity has been narrowed down to a 15 amino acid sequence, and this region is linked to both heparan binding and growth-factor-like properties. It has been proposed that APP binds to heparan sulfate proteoglycans to exert its neuroprotective action. APP presents us with a novel therapeutic compound that could overcome many of the challenges that have stalled development of efficacious TBI treatments previously.
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Affiliation(s)
- Stephanie Plummer
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Corinna Van den Heuvel
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Emma Thornton
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Frances Corrigan
- Adelaide Centre for Neuroscience Research, the University of Adelaide, South Australia, Australia
| | - Roberto Cappai
- Department of Pathology, the University of Melbourne, Victoria, Australia
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Pintana H, Pratchayasakul W, Sa-nguanmoo P, Pongkan W, Tawinvisan R, Chattipakorn N, Chattipakorn SC. Testosterone deprivation has neither additive nor synergistic effects with obesity on the cognitive impairment in orchiectomized and/or obese male rats. Metabolism 2016; 65:54-67. [PMID: 26773929 DOI: 10.1016/j.metabol.2015.10.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 10/02/2015] [Accepted: 10/05/2015] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Previous studies demonstrated a correlation between cognitive decline and either testosterone deprivation or obesity. However, the effect of obesity combined with testosterone deprivation on cognitive function has not been investigated. This study investigated the effects of obesity on brain insulin sensitivity, brain mitochondrial function, hippocampal synaptic plasticity and cognitive function in testosterone-deprived male rats. MATERIALS/METHODS Male Wistar rats were divided into sham-operated (control) and bilateral orchiectomized (ORX) groups. Rats in each group were further divided into two subgroups to receive either a normal diet (ND) or a high fat diet (HFD) for 4, 8 or 12weeks. Blood samples were collected to determine metabolic parameters. Cognitive function was tested using the Morris Water Maze Test. At the end of the study, brains were removed to investigate brain insulin sensitivity, brain mitochondrial function and hippocampal synaptic plasticity. RESULTS Both control-obese and ORX-obese rats developed peripheral insulin resistance at week eight, and brain insulin resistance as well as brain mitochondrial dysfunction at week 12. However, the ORX-obese rats developed cognitive impairment and decreased hippocampal synaptic plasticity beginning at week eight, whereas the control-obese rats developed these impairments later at week 12. Although both peripheral and brain insulin resistance were not observed in both the control-lean and ORX-lean rats, impaired cognition and decreased hippocampal synaptic plasticity were found in the ORX-lean rats beginning at week eight. CONCLUSION These findings suggest that testosterone deprivation has neither additive nor synergistic effects over obesity in the development of cognitive dysfunction in orchiectomized-obese male rats.
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Affiliation(s)
- Hiranya Pintana
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Wasana Pratchayasakul
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Piangkwan Sa-nguanmoo
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Wanpitak Pongkan
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Rungroj Tawinvisan
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Nipon Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Siriporn C Chattipakorn
- Neurophysiology Unit, Cardiac Electrophysiology Research and Training Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand; Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.
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80
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Singh SK, Srivastav S, Yadav AK, Srikrishna S, Perry G. Overview of Alzheimer's Disease and Some Therapeutic Approaches Targeting Aβ by Using Several Synthetic and Herbal Compounds. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2016:7361613. [PMID: 27034741 PMCID: PMC4807045 DOI: 10.1155/2016/7361613] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 11/05/2015] [Indexed: 01/10/2023]
Abstract
Alzheimer's disease (AD) is a complex age-related neurodegenerative disease. In this review, we carefully detail amyloid-β metabolism and its role in AD. We also consider the various genetic animal models used to evaluate therapeutics. Finally, we consider the role of synthetic and plant-based compounds in therapeutics.
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Affiliation(s)
- Sandeep Kumar Singh
- Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005, India
| | - Saurabh Srivastav
- Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005, India
| | - Amarish Kumar Yadav
- Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005, India
| | - Saripella Srikrishna
- Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005, India
| | - George Perry
- Department of Biology, The University of Texas at San Antonio, San Antonio, TX 78249, USA
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81
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Fedele E, Rivera D, Marengo B, Pronzato MA, Ricciarelli R. Amyloid β: Walking on the dark side of the moon. Mech Ageing Dev 2015; 152:1-4. [DOI: 10.1016/j.mad.2015.09.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 08/31/2015] [Accepted: 09/03/2015] [Indexed: 12/20/2022]
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82
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Crenshaw E, Leung BP, Kwok CK, Sharoni M, Olson K, Sebastian NP, Ansaloni S, Schweitzer-Stenner R, Akins MR, Bevilacqua PC, Saunders AJ. Amyloid Precursor Protein Translation Is Regulated by a 3'UTR Guanine Quadruplex. PLoS One 2015; 10:e0143160. [PMID: 26618502 PMCID: PMC4664259 DOI: 10.1371/journal.pone.0143160] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 11/02/2015] [Indexed: 12/13/2022] Open
Abstract
A central event in Alzheimer’s disease is the accumulation of amyloid β (Aβ) peptides generated by the proteolytic cleavage of the amyloid precursor protein (APP). APP overexpression leads to increased Aβ generation and Alzheimer’s disease in humans and altered neuronal migration and increased long term depression in mice. Conversely, reduction of APP expression results in decreased Aβ levels in mice as well as impaired learning and memory and decreased numbers of dendritic spines. Together these findings indicate that therapeutic interventions that aim to restore APP and Aβ levels must do so within an ideal range. To better understand the effects of modulating APP levels, we explored the mechanisms regulating APP expression focusing on post-transcriptional regulation. Such regulation can be mediated by RNA regulatory elements such as guanine quadruplexes (G-quadruplexes), non-canonical structured RNA motifs that affect RNA stability and translation. Via a bioinformatics approach, we identified a candidate G-quadruplex within the APP mRNA in its 3’UTR (untranslated region) at residues 3008–3027 (NM_201414.2). This sequence exhibited characteristics of a parallel G-quadruplex structure as revealed by circular dichroism spectrophotometry. Further, as with other G-quadruplexes, the formation of this structure was dependent on the presence of potassium ions. This G-quadruplex has no apparent role in regulating transcription or mRNA stability as wild type and mutant constructs exhibited equivalent mRNA levels as determined by real time PCR. Instead, we demonstrate that this G-quadruplex negatively regulates APP protein expression using dual luciferase reporter and Western blot analysis. Taken together, our studies reveal post-transcriptional regulation by a 3’UTR G-quadruplex as a novel mechanism regulating APP expression.
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Affiliation(s)
- Ezekiel Crenshaw
- Department of Biology, Drexel University, Philadelphia, PA, United States of America
| | - Brian P. Leung
- Department of Biology, Drexel University, Philadelphia, PA, United States of America
- Department of Chemistry, Drexel University, Philadelphia, PA, United States of America
| | - Chun Kit Kwok
- Department of Chemistry, Pennsylvania State University, University Park, PA, United States of America
- Department of Biochemistry & Molecular Biology, Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA, United States of America
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Michal Sharoni
- Department of Biology, Drexel University, Philadelphia, PA, United States of America
| | - Kalee Olson
- Department of Chemistry, Pennsylvania State University, University Park, PA, United States of America
| | - Neeraj P. Sebastian
- Department of Biology, Drexel University, Philadelphia, PA, United States of America
| | - Sara Ansaloni
- Department of Biology, Drexel University, Philadelphia, PA, United States of America
| | | | - Michael R. Akins
- Department of Biology, Drexel University, Philadelphia, PA, United States of America
- Department of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States of America
| | - Philip C. Bevilacqua
- Department of Chemistry, Pennsylvania State University, University Park, PA, United States of America
- Department of Biochemistry & Molecular Biology, Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA, United States of America
| | - Aleister J. Saunders
- Department of Biology, Drexel University, Philadelphia, PA, United States of America
- Department of Biochemistry & Molecular Biology, Drexel University College of Medicine, Philadelphia, PA, United States of America
- Department of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States of America
- * E-mail:
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83
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Fanutza T, Del Prete D, Ford MJ, Castillo PE, D'Adamio L. APP and APLP2 interact with the synaptic release machinery and facilitate transmitter release at hippocampal synapses. eLife 2015; 4:e09743. [PMID: 26551565 PMCID: PMC4755753 DOI: 10.7554/elife.09743] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 11/08/2015] [Indexed: 12/16/2022] Open
Abstract
The amyloid precursor protein (APP), whose mutations cause familial Alzheimer's disease, interacts with the synaptic release machinery, suggesting a role in neurotransmission. Here we mapped this interaction to the NH2-terminal region of the APP intracellular domain. A peptide encompassing this binding domain -named JCasp- is naturally produced by a γ-secretase/caspase double-cut of APP. JCasp interferes with the APP-presynaptic proteins interaction and, if linked to a cell-penetrating peptide, reduces glutamate release in acute hippocampal slices from wild-type but not APP deficient mice, indicating that JCasp inhibits APP function.The APP-like protein-2 (APLP2) also binds the synaptic release machinery. Deletion of APP and APLP2 produces synaptic deficits similar to those caused by JCasp. Our data support the notion that APP and APLP2 facilitate transmitter release, likely through the interaction with the neurotransmitter release machinery. Given the link of APP to Alzheimer's disease, alterations of this synaptic role of APP could contribute to dementia.
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Affiliation(s)
- Tomas Fanutza
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, United States
| | - Dolores Del Prete
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, United States
| | | | - Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, United States
| | - Luciano D'Adamio
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, New York, United States
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84
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Puzzo D, Gulisano W, Arancio O, Palmeri A. The keystone of Alzheimer pathogenesis might be sought in Aβ physiology. Neuroscience 2015; 307:26-36. [PMID: 26314631 PMCID: PMC4591241 DOI: 10.1016/j.neuroscience.2015.08.039] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/15/2015] [Accepted: 08/18/2015] [Indexed: 01/17/2023]
Abstract
For several years Amyloid-beta peptide (Aβ) has been considered the main pathogenetic factor of Alzheimer's disease (AD). According to the so called Amyloid Cascade Hypothesis the increase of Aβ triggers a series of events leading to synaptic dysfunction and memory loss as well as to the structural brain damage in the later stage of the disease. However, several evidences suggest that this hypothesis is not sufficient to explain AD pathogenesis, especially considering that most of the clinical trials aimed to decrease Aβ levels have been unsuccessful. Moreover, Aβ is physiologically produced in the healthy brain during neuronal activity and it is needed for synaptic plasticity and memory. Here we propose a model interpreting AD pathogenesis as an alteration of the negative feedback loop between Aβ and its physiological receptors, focusing on alpha7 nicotinic acetylcholine receptors (α7-nAchRs). According to this vision, when Aβ cannot exert its physiological function a negative feedback mechanism would induce a compensatory increase of its production leading to an abnormal accumulation that reduces α7-nAchR function, leading to synaptic dysfunction and memory loss. In this perspective, the indiscriminate Aβ removal might worsen neuronal homeostasis, causing a further impoverishment of learning and memory. Even if further studies are needed to better understand and validate these mechanisms, we believe that to deepen the role of Aβ in physiological conditions might represent the keystone to elucidate important aspects of AD pathogenesis.
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Affiliation(s)
- D Puzzo
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, Viale A. Doria 6 (ed. 2), University of Catania, Catania 95125, Italy.
| | - W Gulisano
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, Viale A. Doria 6 (ed. 2), University of Catania, Catania 95125, Italy
| | - O Arancio
- Department of Pathology and Cell Biology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, 630 West 168th Street, Columbia University, New York, NY 10032, USA
| | - A Palmeri
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, Viale A. Doria 6 (ed. 2), University of Catania, Catania 95125, Italy
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85
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Hosono T, Mouri A, Nishitsuji K, Jung CG, Kontani M, Tokuda H, Kawashima H, Shibata H, Suzuki T, Nabehsima T, Michikawa M. Arachidonic or Docosahexaenoic Acid Diet Prevents Memory Impairment in Tg2576 Mice. J Alzheimers Dis 2015; 48:149-62. [DOI: 10.3233/jad-150341] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Takashi Hosono
- Department of Chemistry and Life Science, Nihon University Graduate School of Bioresource Sciences, Fujisawa, Japan
- Department of Alzheimer’s Disease, National Center for Geriatrics and Gerontology, Obu, Japan
| | - Akihiro Mouri
- Division of Clinical Sciences and Neuropsychopharmacology, Faculty of Pharmacy, Meijo University, Nagoya, Japan
- NPO Japanese Drug Organization of Appropriate Use and Research, Nagoya, Japan
| | - Kazuchika Nishitsuji
- Department of Alzheimer’s Disease, National Center for Geriatrics and Gerontology, Obu, Japan
- Department of Molecular Pathology, Institute of Biomedical Science, The University of Tokushima Graduate School, Tokushima, Japan
| | - Cha-Gyun Jung
- Department of Alzheimer’s Disease, National Center for Geriatrics and Gerontology, Obu, Japan
- Department of Neurophysiology and Brain Science, Nagoya City University, School of Medical Sciences, Nagoya, Japan
| | - Masanori Kontani
- Institute for Health Care Science, Suntory Wellness Ltd., Osaka, Japan
| | - Hisanori Tokuda
- Institute for Health Care Science, Suntory Wellness Ltd., Osaka, Japan
| | - Hiroshi Kawashima
- Institute for Health Care Science, Suntory Wellness Ltd., Osaka, Japan
| | - Hiroshi Shibata
- Institute for Health Care Science, Suntory Wellness Ltd., Osaka, Japan
| | - Toshiharu Suzuki
- Laboratory of Neuroscience, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Toshitaka Nabehsima
- NPO Japanese Drug Organization of Appropriate Use and Research, Nagoya, Japan
- Nabeshima Laboratory, Department of Pharmacy, Meijyo University, Nagoya, Japan
| | - Makoto Michikawa
- Department of Alzheimer’s Disease, National Center for Geriatrics and Gerontology, Obu, Japan
- Department of Biochemistry, Nagoya City University, School of Medical Sciences, Nagoya, Japan
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86
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Gautam V, D'Avanzo C, Berezovska O, Tanzi RE, Kovacs DM. Synaptotagmins interact with APP and promote Aβ generation. Mol Neurodegener 2015. [PMID: 26202512 PMCID: PMC4511450 DOI: 10.1186/s13024-015-0028-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Background Accumulation of the β-amyloid peptide (Aβ) is a major pathological hallmark of Alzheimer’s disease (AD). Recent studies have shown that synaptic Aβ toxicity may directly impair synaptic function. However, proteins regulating Aβ generation at the synapse have not been characterized. Here, we sought to identify synaptic proteins that interact with the extracellular domain of APP and regulate Aβ generation. Results Affinity purification-coupled mass spectrometry identified members of the Synaptotagmin (Syt) family as novel interacting proteins with the APP ectodomain in mouse brains. Syt-1, −2 and −9 interacted with APP in cells and in mouse brains in vivo. Using a GST pull-down approach, we have further demonstrated that the Syt interaction site lies in the 108 amino acids linker region between the E1 and KPI domains of APP. Stable overexpression of Syt-1 or Syt-9 with APP in CHO and rat pheochromocytoma cells (PC12) significantly increased APP-CTF and sAPP levels, with a 2 to 3 fold increase in secreted Aβ levels in PC12 cells. Moreover, using a stable knockdown approach to reduce the expression of endogenous Syt-1 in PC12 cells, we have observed a ~ 50 % reduction in secreted Aβ generation. APP processing also decreased in these cells, shown by lower CTF levels. Lentiviral-mediated knock down of endogenous Syt-1 in mouse primary neurons also led to a significant reduction in both Aβ40 and Aβ42 generation. As secreted sAPPβ levels were significantly reduced in PC12 cells lacking Syt-1 expression, our results suggest that Syt-1 regulates Aβ generation by modulating BACE1-mediated cleavage of APP. Conclusion Altogether, our data identify the synaptic vesicle proteins Syt-1 and 9 as novel APP-interacting proteins that promote Aβ generation and thus may play an important role in the pathogenesis of AD. Electronic supplementary material The online version of this article (doi:10.1186/s13024-015-0028-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Vivek Gautam
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA.
| | - Carla D'Avanzo
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA.
| | - Oksana Berezovska
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA.
| | - Rudolph E Tanzi
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA.
| | - Dora M Kovacs
- Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA.
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87
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van der Kant R, Goldstein LSB. Cellular functions of the amyloid precursor protein from development to dementia. Dev Cell 2015; 32:502-15. [PMID: 25710536 DOI: 10.1016/j.devcel.2015.01.022] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Amyloid precursor protein (APP) is a key player in Alzheimer's disease (AD). The Aβ fragments of APP are the major constituent of AD-associated amyloid plaques, and mutations or duplications of the gene coding for APP can cause familial AD. Here we review the roles of APP in neuronal development, signaling, intracellular transport, and other aspects of neuronal homeostasis. We suggest that APP acts as a signaling nexus that transduces information about a range of extracellular conditions, including neuronal damage, to induction of intracellular signaling events. Subtle disruptions of APP signaling functions may be major contributors to AD-causing neuronal dysfunction.
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Affiliation(s)
- Rik van der Kant
- Department of Cellular and Molecular Medicine, University of California-San Diego, La Jolla, CA 92093, USA.
| | - Lawrence S B Goldstein
- Department of Cellular and Molecular Medicine, University of California-San Diego, La Jolla, CA 92093, USA.
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88
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Vnencak M, Paul MH, Hick M, Schwarzacher SW, Del Turco D, Müller UC, Deller T, Jedlicka P. Deletion of the amyloid precursor-like protein 1 (APLP1) enhances excitatory synaptic transmission, reduces network inhibition but does not impair synaptic plasticity in the mouse dentate gyrus. J Comp Neurol 2015; 523:1717-29. [PMID: 25728909 DOI: 10.1002/cne.23766] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/21/2015] [Accepted: 02/23/2015] [Indexed: 01/02/2023]
Abstract
Amyloid precursor-like protein 1 (APLP1) is a transmembrane synaptic protein belonging to the amyloid precursor protein (APP) gene family. Although the role of this gene family-in particular of APP-has been intensely studied in the context of Alzheimer's disease, the physiological roles of its family members remain poorly understood. In particular, the function of APLP1, which is predominantly expressed in the nervous system, has remained enigmatic. Since APP has been implicated in synaptic plasticity, we wondered whether APLP1 could play a similar role. First, using in situ hybridization and laser microdissection combined with reverse transcription-quantitative polymerase chain reaction (PCR) we observed that Aplp1 mRNA is highly expressed in dentate granule cells. Having this examined, we studied synaptic plasticity at the perforant path-granule cell synapses in the dentate gyrus of APLP1-deficient mice in vivo. Analysis of field excitatory postsynaptic potentials evoked by stimulation of perforant path fibers revealed increased excitatory transmission in APLP1-deficient mice. Moreover, we observed decreased paired-pulse inhibition of population spikes indicating a decrease in network inhibition upon deletion of APLP1. In contrast, short-term presynaptic plasticity (STP) as well as long-term synaptic plasticity (LTP) was unchanged in the absence of APLP1. Based on these results we conclude that APLP1 deficiency on its own does not lead to defects in synaptic plasticity, but affects synaptic transmission and network inhibition in the dentate gyrus.
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Affiliation(s)
- Matej Vnencak
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Mandy H Paul
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Meike Hick
- Department of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Stephan W Schwarzacher
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Domenico Del Turco
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Ulrike C Müller
- Department of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
| | - Peter Jedlicka
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt am Main, Germany
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89
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Aboud O, Parcon PA, DeWall KM, Liu L, Mrak RE, Griffin WST. Aging, Alzheimer's, and APOE genotype influence the expression and neuronal distribution patterns of microtubule motor protein dynactin-P50. Front Cell Neurosci 2015; 9:103. [PMID: 25859183 PMCID: PMC4373372 DOI: 10.3389/fncel.2015.00103] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 03/09/2015] [Indexed: 01/21/2023] Open
Abstract
Reports from neural cell cultures and experimental animal studies provide evidence of age- and disease-related changes in retrograde transport of spent or misfolded proteins destined for degradation or recycling. However, few studies address these issues in human brain from those who either age without dementia and overt neuropathology, or succumb to Alzheimer's; especially as such propensity may be influenced by APOE genotype. We studied the expression and distribution of the dynein subunit dynactin-P50, the β amyloid precursor protein (βAPP), and hyperphosphorylated tau (P-tau) in tissues and tissue sections of brains from non-demented, neuropathology-free patients and from Alzheimer patients, with either APOE ε3,3 or APOE ε4,4. We found that advanced age in patients without dementia or neuropathological change was associated with coordinated increases in dynactin-P50 and βAPP in neurons in pyramidal layers of the hippocampus. In contrast, in Alzheimer's, βAPP and dynactin were significantly reduced. Furthermore, the dynactin-P50 and βAPP that was present was located primarily in dystrophic neurites in Aβ plaques. Tissues from Alzheimer patients with APOE ε3,3 had less P-tau, more βAPP, dynactin-P50, and synaptophysin than did tissues from Alzheimer patients carrying APOE ε4,4. It is logical to conclude, then, that as neurons age successfully, there is coordination between retrograde delivery and maintenance and repair, as well as between retrograde delivery and degradation and/or recycling of spent proteins. The buildup of proteins slated for repair, synaptic viability, transport, and re-cycling in neuron soma and dystrophic neurites suggest a loss of this coordination in Alzheimer neurons. Inheritance of APOE ε3,3 rather than APOE ε4,4, is associated with neuronal resilience, suggestive of better repair capabilities, more synapses, more efficient transport, and less hyperphosphorylation of tau. We conclude that even in disease the ε3 allele is neuroprotective.
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Affiliation(s)
- Orwa Aboud
- Donald W. Reynolds Department of Geriatrics, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - Paul A Parcon
- Donald W. Reynolds Department of Geriatrics, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - K Mark DeWall
- Donald W. Reynolds Department of Geriatrics, University of Arkansas for Medical Sciences Little Rock, AR, USA ; Department of Biology, Brigham Young University Idaho, Rexburg, ID, USA
| | - Ling Liu
- Donald W. Reynolds Department of Geriatrics, University of Arkansas for Medical Sciences Little Rock, AR, USA
| | - Robert E Mrak
- Department of Pathology, University of Toledo Health Sciences Campus Toledo, OH, USA
| | - W Sue T Griffin
- Donald W. Reynolds Department of Geriatrics, University of Arkansas for Medical Sciences Little Rock, AR, USA ; Geriatric Research, Education, Clinical Center, Central Arkansas HealthCare System Little Rock, AR, USA
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90
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Leonova EI, Galzitskaya OV. Role of Syndecans in Lipid Metabolism and Human Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 855:241-58. [PMID: 26149933 DOI: 10.1007/978-3-319-17344-3_10] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Syndecans are transmembrane heparan sulfate proteoglycans involved in the regulation of cell growth, differentiation, adhesion, neuronal development, and lipid metabolism. Syndecans are expressed in a tissue-specific manner to facilitate diverse cellular processes. As receptors and co-receptors, syndecans provide promising therapeutic targets that bind to a variety of physiologically important ligands. Negatively charged glycosaminoglycan chains of syndecans, located in the extracellular compartment, are critical for such binding. Functions of syndecans are as diverse as their ligands. For example, hepatic syndecan-1 mediates clearance of triglyceride-rich lipoproteins. Syndecan-2 promotes localization of Alzheimer's amyloid Aβ peptide to the cell surface, which is proposed to contribute to amyloid plaque formation. Syndecan-3 helps co-localize the appetite-regulating melanocortin-4 receptor with its agonist, leading to an increased appetite. Finally, syndecan-4 initiates the capture of modified low-density lipoproteins by macrophages and thereby promotes the atheroma formation. We hypothesize that syndecan modifications such as desulfation of glycosaminoglycan chains may contribute to a wide range of diseases, from atherosclerosis to type 2 diabetes. At the same time, desulfated syndecans may have beneficial effects, as they can inhibit amyloid plaque formation or decrease the appetite. Despite considerable progress in understanding diverse functions of syndecans, the complex physiological roles of this intriguing family of proteoglycans are far from clear. Additional studies of syndecans may potentially help develop novel therapeutic approaches and diagnostic tools to alleviate complex human diseases such as cardiovascular and Alzheimer's diseases.
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Affiliation(s)
- Elena I Leonova
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia,
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91
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Hick M, Herrmann U, Weyer SW, Mallm JP, Tschäpe JA, Borgers M, Mercken M, Roth FC, Draguhn A, Slomianka L, Wolfer DP, Korte M, Müller UC. Acute function of secreted amyloid precursor protein fragment APPsα in synaptic plasticity. Acta Neuropathol 2015; 129:21-37. [PMID: 25432317 DOI: 10.1007/s00401-014-1368-x] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 11/11/2014] [Accepted: 11/12/2014] [Indexed: 11/24/2022]
Abstract
The key role of APP in the pathogenesis of Alzheimer disease is well established. However, postnatal lethality of double knockout mice has so far precluded the analysis of the physiological functions of APP and the APLPs in the brain. Previously, APP family proteins have been implicated in synaptic adhesion, and analysis of the neuromuscular junction of constitutive APP/APLP2 mutant mice showed deficits in synaptic morphology and neuromuscular transmission. Here, we generated animals with a conditional APP/APLP2 double knockout (cDKO) in excitatory forebrain neurons using NexCre mice. Electrophysiological recordings of adult NexCre cDKOs indicated a strong synaptic phenotype with pronounced deficits in the induction and maintenance of hippocampal LTP and impairments in paired pulse facilitation, indicating a possible presynaptic deficit. These deficits were also reflected in impairments in nesting behavior and hippocampus-dependent learning and memory tasks, including deficits in Morris water maze and radial maze performance. Moreover, while no gross alterations of brain morphology were detectable in NexCre cDKO mice, quantitative analysis of adult hippocampal CA1 neurons revealed prominent reductions in total neurite length, dendritic branching, reduced spine density and reduced spine head volume. Strikingly, the impairment of LTP could be selectively rescued by acute application of exogenous recombinant APPsα, but not APPsβ, indicating a crucial role for APPsα to support synaptic plasticity of mature hippocampal synapses on a rapid time scale. Collectively, our analysis reveals an essential role of APP family proteins in excitatory principal neurons for mediating normal dendritic architecture, spine density and morphology, synaptic plasticity and cognition.
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Affiliation(s)
- Meike Hick
- 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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92
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Skalska J, Frontczak-Baniewicz M, Strużyńska L. Synaptic degeneration in rat brain after prolonged oral exposure to silver nanoparticles. Neurotoxicology 2014; 46:145-54. [PMID: 25447321 DOI: 10.1016/j.neuro.2014.11.002] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/11/2014] [Accepted: 11/07/2014] [Indexed: 01/28/2023]
Abstract
Neurotoxicity of silver nanoparticles has been confirmed in both in vitro and in vivo studies. However, the mechanisms of the toxic action have not been fully clarified. Since nanoparticles are likely to have the ability to enter the brain and significantly accumulate in this organ, it is important to investigate their neurotoxic mechanisms. Here we examine the effect of prolonged exposure of rats to small (10nm) citrate-stabilized silver nanoparticles (as opposed to the ionic silver) on synapse ultrastructure and specific proteins. Administration of both nanosilver and ionic silver over a two-week period resulted in ultrastructural changes including blurred synapse structure and strongly enhanced density of synaptic vesicles clustering in the center of the presynaptic part. Disturbed synaptic membrane leading to liberation of synaptic vesicles into neuropil, which testifies for strong synaptic degeneration, was characteristic feature observed under AgNPs exposure. Also a noteworthy finding was the presence of myelin-like structures derived from fragmented membranes and organelles which are associated with neurodegenerative processes. Additionally, we observed significantly decreased levels of the presynaptic proteins synapsin I and synaptophysin, as well as PSD-95 protein which is an indicator of postsynaptic densities. The present study demonstrates that exposure of adult rats to both forms of silver leads to ultrastructural changes in synapses. However, it seems that small AgNPs lead to more severe synaptic degeneration, mainly in the hippocampal region of brain. The observations may indicate impairment of nerve function and, in the case of hippocampus, may predict impairment of cognitive processes.
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Affiliation(s)
- Joanna Skalska
- Laboratory of Pathoneurochemistry, Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego Str., 02-106 Warsaw, Poland
| | - Małgorzata Frontczak-Baniewicz
- Electron Microscopy Platform, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego Str., 02-106 Warsaw, Poland
| | - Lidia Strużyńska
- Laboratory of Pathoneurochemistry, Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego Str., 02-106 Warsaw, Poland.
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93
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Vorobyeva AG, Lee R, Miller S, Longen C, Sharoni M, Kandelwal PJ, Kim FJ, Marenda DR, Saunders AJ. Cyclopamine modulates γ-secretase-mediated cleavage of amyloid precursor protein by altering its subcellular trafficking and lysosomal degradation. J Biol Chem 2014; 289:33258-74. [PMID: 25281744 DOI: 10.1074/jbc.m114.591792] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Alzheimer disease (AD) is a progressive neurodegenerative disease leading to memory loss. Numerous lines of evidence suggest that amyloid-β (Aβ), a neurotoxic peptide, initiates a cascade that results in synaptic dysfunction, neuronal death, and eventually cognitive deficits. Aβ is generated by the proteolytic processing of the amyloid precursor protein (APP), and alterations to this processing can result in Alzheimer disease. Using in vitro and in vivo models, we identified cyclopamine as a novel regulator of γ-secretase-mediated cleavage of APP. We demonstrate that cyclopamine decreases Aβ generation by altering APP retrograde trafficking. Specifically, cyclopamine treatment reduced APP-C-terminal fragment (CTF) delivery to the trans-Golgi network where γ-secretase cleavage occurs. Instead, cyclopamine redirects APP-CTFs to the lysosome. These data demonstrate that cyclopamine treatment decreases γ-secretase-mediated cleavage of APP. In addition, cyclopamine treatment decreases the rate of APP-CTF degradation. Together, our data demonstrate that cyclopamine alters APP processing and Aβ generation by inducing changes in APP subcellular trafficking and APP-CTF degradation.
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Affiliation(s)
- Anna G Vorobyeva
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | - Randall Lee
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | - Sean Miller
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | | | - Michal Sharoni
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | - Preeti J Kandelwal
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and
| | - Felix J Kim
- the Departments of Pharmacology and Physiology
| | - Daniel R Marenda
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and Neurobiology and Anatomy, and
| | - Aleister J Saunders
- From the Department of Biology, Drexel University, Philadelphia, Pennsylvania 19104 and Neurobiology and Anatomy, and Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102
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94
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Del Prete D, Lombino F, Liu X, D'Adamio L. APP is cleaved by Bace1 in pre-synaptic vesicles and establishes a pre-synaptic interactome, via its intracellular domain, with molecular complexes that regulate pre-synaptic vesicles functions. PLoS One 2014; 9:e108576. [PMID: 25247712 PMCID: PMC4172690 DOI: 10.1371/journal.pone.0108576] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 08/31/2014] [Indexed: 12/21/2022] Open
Abstract
Amyloid Precursor Protein (APP) is a type I membrane protein that undergoes extensive processing by secretases, including BACE1. Although mutations in APP and genes that regulate processing of APP, such as PSENs and BRI2/ITM2B, cause dementias, the normal function of APP in synaptic transmission, synaptic plasticity and memory formation is poorly understood. To grasp the biochemical mechanisms underlying the function of APP in the central nervous system, it is important to first define the sub-cellular localization of APP in synapses and the synaptic interactome of APP. Using biochemical and electron microscopy approaches, we have found that APP is localized in pre-synaptic vesicles, where it is processed by Bace1. By means of a proteomic approach, we have characterized the synaptic interactome of the APP intracellular domain. We focused on this region of APP because in vivo data underline the central functional and pathological role of the intracellular domain of APP. Consistent with the expression of APP in pre-synaptic vesicles, the synaptic APP intracellular domain interactome is predominantly constituted by pre-synaptic, rather than post-synaptic, proteins. This pre-synaptic interactome of the APP intracellular domain includes proteins expressed on pre-synaptic vesicles such as the vesicular SNARE Vamp2/Vamp1 and the Ca2+ sensors Synaptotagmin-1/Synaptotagmin-2, and non-vesicular pre-synaptic proteins that regulate exocytosis, endocytosis and recycling of pre-synaptic vesicles, such as target-membrane-SNAREs (Syntaxin-1b, Syntaxin-1a, Snap25 and Snap47), Munc-18, Nsf, α/β/γ-Snaps and complexin. These data are consistent with a functional role for APP, via its carboxyl-terminal domain, in exocytosis, endocytosis and/or recycling of pre-synaptic vesicles.
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Affiliation(s)
- Dolores Del Prete
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Franco Lombino
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Xinran Liu
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Luciano D'Adamio
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
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95
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Vassar R, Kuhn PH, Haass C, Kennedy ME, Rajendran L, Wong PC, Lichtenthaler SF. Function, therapeutic potential and cell biology of BACE proteases: current status and future prospects. J Neurochem 2014; 130:4-28. [PMID: 24646365 PMCID: PMC4086641 DOI: 10.1111/jnc.12715] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 03/12/2014] [Accepted: 03/14/2014] [Indexed: 01/18/2023]
Abstract
The β-site APP cleaving enzymes 1 and 2 (BACE1 and BACE2) were initially identified as transmembrane aspartyl proteases cleaving the amyloid precursor protein (APP). BACE1 is a major drug target for Alzheimer's disease because BACE1-mediated cleavage of APP is the first step in the generation of the pathogenic amyloid-β peptides. BACE1, which is highly expressed in the nervous system, is also required for myelination by cleaving neuregulin 1. Several recent proteomic and in vivo studies using BACE1- and BACE2-deficient mice demonstrate a much wider range of physiological substrates and functions for both proteases within and outside of the nervous system. For BACE1 this includes axon guidance, neurogenesis, muscle spindle formation, and neuronal network functions, whereas BACE2 was shown to be involved in pigmentation and pancreatic β-cell function. This review highlights the recent progress in understanding cell biology, substrates, and functions of BACE proteases and discusses the therapeutic options and potential mechanism-based liabilities, in particular for BACE inhibitors in Alzheimer's disease. The protease BACE1 is a major drug target in Alzheimer disease. Together with its homolog BACE2, both proteases have an increasing number of functions within and outside of the nervous system. This review highlights recent progress in understanding cell biology, substrates, and functions of BACE proteases and discusses the therapeutic options and potential mechanism-based liabilities, in particular for BACE inhibitors in Alzheimer disease.
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Affiliation(s)
- Robert Vassar
- Department of Cell and Molecular Biology, Feinberg University School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Peer-Hendrik Kuhn
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Neuroproteomics, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
- Institute for Advanced Study, Technische Universität München, Garching, Germany
| | - Christian Haass
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
- Adolf-Butenandt Institute, Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany
| | - Matthew E. Kennedy
- Neurosciences, Merck Research Labs, Boston, Massachusetts, USA
- Division of Psychiatry Research, University of Zurich, Zurich, Switzerland
| | - Lawrence Rajendran
- Systems and Cell Biology of Neurodegeneration, Division of Psychiatry Research, University of Zurich, Zurich, Switzerland
- Graduate programs of the Zurich Center for Integrative Human Physiology and Zurich Neuroscience Center, University of Zurich, Zurich, Switzerland
| | - Philip C. Wong
- Departments of Pathology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Stefan F. Lichtenthaler
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
- Neuroproteomics, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
- Institute for Advanced Study, Technische Universität München, Garching, Germany
- Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
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96
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A death receptor 6-amyloid precursor protein pathway regulates synapse density in the mature CNS but does not contribute to Alzheimer's disease-related pathophysiology in murine models. J Neurosci 2014; 34:6425-37. [PMID: 24806669 DOI: 10.1523/jneurosci.4963-13.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Recent studies implicate death receptor 6 (DR6) in an amyloid precursor protein (APP)-dependent pathway regulating developmental axon pruning, and in a pruning pathway operating during plastic rearrangements in adult brain. DR6 has also been suggested to mediate toxicity in vitro of Aβ peptides derived from APP. Given the link between APP, Aβ, and Alzheimer's disease (AD), these findings have raised the possibility that DR6 contributes to aspects of neurodegeneration in AD. To test this possibility, we have used mouse models to characterize potential function(s) of DR6 in the adult CNS and in AD-related pathophysiology. We show that DR6 is broadly expressed within the adult CNS and regulates the density of excitatory synaptic connections onto pyramidal neurons in a genetic pathway with APP. DR6 knock-out also gives rise to behavioral abnormalities, some of which are similar to those previously documented in APP knock-out animals. However, in two distinct APP transgenic models of AD, we did not observe any alteration in the formation of amyloid plaques, gliosis, synaptic loss, or cognitive behavioral deficits with genetic deletion of DR6, though we did observe a transient reduction in the degree of microglial activation in one model. Our results support the view that DR6 functions with APP to modulate synaptic density in the adult CNS, but do not provide evidence for a role of DR6 in the pathophysiology of AD.
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97
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Epigenetic regulations of immediate early genes expression involved in memory formation by the amyloid precursor protein of Alzheimer disease. PLoS One 2014; 9:e99467. [PMID: 24919190 PMCID: PMC4053420 DOI: 10.1371/journal.pone.0099467] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 05/14/2014] [Indexed: 11/19/2022] Open
Abstract
We previously demonstrated that APP epigenetically regulates Egr1 expression both in cultured neurons and in vivo. Since Egr1 is an immediate early gene involved in memory formation, we wondered whether other early genes involved in memory were regulated by APP and we studied molecular mechanisms involved. By comparing prefrontal (PF) cortex from wild type (APP+/+) and APP knockout mice (APP−/−), we observed that APP down regulates expression of four immediate early genes, Egr1, c-Fos, Bdnf and Arc. Down regulation of Egr1, c-Fos and Bdnf transcription resulted from a decreased enrichment of acetylated histone H4 on the corresponding gene promoter. Further characterization of H4 acetylation at Egr1 and c-Fos promoters revealed increased acetylation of H4K5 and H4K12 residues in APP−/− mice. Whereas APP affected Egr1 promoter activity by reducing access of the CREB transcription factor, its effect on c-Fos appeared to depend on increased recruitment of HDAC2 histone deacetylase to the gene promoter. The physiological relevance of the epigenetic regulation of Egr1 and c-Fos gene transcription by APP was further analyzed following exposure of mice to novelty. Although transcription of Egr1 and c-Fos was increased following exposure of APP+/+ mice to novelty, such an induction was not possible in APP−/− mice with a high basal level of expression of these immediate early genes. Altogether, these results demonstrate that APP-mediated regulation of c-Fos and Egr1 by different epigenetic mechanisms is needed for their induction during exposure to novelty.
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98
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Cognitive Enhancing Effects of Alpha Asarone in Amnesic Mice by Influencing Cholinergic and Antioxidant Defense Mechanisms. Biosci Biotechnol Biochem 2014; 76:1518-22. [DOI: 10.1271/bbb.120247] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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99
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Lin AL, Rothman DL. What have novel imaging techniques revealed about metabolism in the aging brain? FUTURE NEUROLOGY 2014; 9:341-354. [PMID: 25214817 DOI: 10.2217/fnl.14.13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Brain metabolism declines with age and do so in an accelerated manner in neurodegenerative disorders. Noninvasive neuroimaging techniques have played an important role to identify the metabolic biomarkers in aging brain. Particularly, PET with fluorine-18 (18F)-labeled 2-fluoro-2-deoxy-d-glucose tracer and proton magnetic resonance spectroscopy (MRS) have been widely used to monitor changes in brain metabolism over time, identify the risk for Alzheimer's disease (AD) and predict the conversion from mild cognitive impairment to AD. Novel techniques, including PET carbon-11 Pittsburgh compound B, carbon-13 and phosphorus-31 MRS, have also been introduced to determine Aβ plaques deposition, mitochondrial functions and brain bioenergetics in aging brain and neurodegenerative disorders. Here, we introduce the basic principle of the imaging techniques, review the findings from 2-fluoro-2-deoxy-d-glucose-PET, Pittsburgh compound B PET, proton, carbon-13 and phosphorus-31 MRS on changes in metabolism in normal aging brain, mild cognitive impairment and AD, and discuss the potential of neuroimaging to identify effective interventions and treatment efficacy for neurodegenerative disorders.
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Affiliation(s)
- Ai-Ling Lin
- Sanders-Brown Center on Aging, Department of Pharmacology & Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Douglas L Rothman
- Magnetic Resonance Research Center, Diagnostic Radiology & Biomedical Engineering, Yale University, New Haven, CT, USA
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100
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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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