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Vitória JJM, Trigo D, da Cruz E Silva OAB. Revisiting APP secretases: an overview on the holistic effects of retinoic acid receptor stimulation in APP processing. Cell Mol Life Sci 2022; 79:101. [PMID: 35089425 PMCID: PMC11073327 DOI: 10.1007/s00018-021-04090-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 11/18/2021] [Accepted: 12/01/2021] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) is the leading cause of dementia worldwide and is characterized by the accumulation of the β-amyloid peptide (Aβ) in the brain, along with profound alterations in phosphorylation-related events and regulatory pathways. The production of the neurotoxic Aβ peptide via amyloid precursor protein (APP) proteolysis is a crucial step in AD development. APP is highly expressed in the brain and is complexly metabolized by a series of sequential secretases, commonly denoted the α-, β-, and γ-cleavages. The toxicity of resulting fragments is a direct consequence of the first cleaving event. β-secretase (BACE1) induces amyloidogenic cleavages, while α-secretases (ADAM10 and ADAM17) result in less pathological peptides. Hence this first cleavage event is a prime therapeutic target for preventing or reverting initial biochemical events involved in AD. The subsequent cleavage by γ-secretase has a reduced impact on Aβ formation but affects the peptides' aggregating capacity. An array of therapeutic strategies are being explored, among them targeting Retinoic Acid (RA) signalling, which has long been associated with neuronal health. Additionally, several studies have described altered RA levels in AD patients, reinforcing RA Receptor (RAR) signalling as a promising therapeutic strategy. In this review we provide a holistic approach focussing on the effects of isoform-specific RAR modulation with respect to APP secretases and discuss its advantages and drawbacks in subcellular AD related events.
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Affiliation(s)
- José J M Vitória
- Department of Medical Sciences, Neurosciences and Signalling Group, Institute of Biomedicine, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Diogo Trigo
- Department of Medical Sciences, Neurosciences and Signalling Group, Institute of Biomedicine, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Odete A B da Cruz E Silva
- Department of Medical Sciences, Neurosciences and Signalling Group, Institute of Biomedicine, University of Aveiro, 3810-193, Aveiro, Portugal.
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2
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Chiu YJ, Hsieh YH, Lin TH, Lee GC, Hsieh-Li HM, Sun YC, Chen CM, Chang KH, Lee-Chen GJ. Novel compound VB-037 inhibits Aβ aggregation and promotes neurite outgrowth through enhancement of HSP27 and reduction of P38 and JNK-mediated inflammation in cell models for Alzheimer's disease. Neurochem Int 2019; 125:175-186. [DOI: 10.1016/j.neuint.2019.01.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 01/21/2019] [Accepted: 01/25/2019] [Indexed: 01/20/2023]
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3
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Rosa IM, Henriques AG, Carvalho L, Oliveira J, da Cruz E Silva OAB. Screening Younger Individuals in a Primary Care Setting Flags Putative Dementia Cases and Correlates Gastrointestinal Diseases with Poor Cognitive Performance. Dement Geriatr Cogn Disord 2018; 43:15-28. [PMID: 27907913 DOI: 10.1159/000452485] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/13/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Diagnosing dementia is challenging in many primary care settings, given the limited human resources and the lack of current diagnostic tools. With this in mind, a primary care-based cohort was established in the Aveiro district of Portugal. METHODS A total of 568 participants were evaluated using cognitive tests and APOE genotyping. RESULTS The findings revealed a dementia prevalence of 12%. A strong correlation between increasing Clinical Dementia Rating (CDR) scores and education was clearly evident. Other highly relevant risk factors were activities of daily living (ADL), instrumental ADL, aging, depression, gender, the APOE ε4 allele, and comorbidities (depression as well as gastrointestinal, osteoarticular, and neurodegenerative diseases). A hitherto unreported, significant correlation between gastrointestinal disease and high CDR score was clearly observable. CONCLUSIONS This study shows the merit of carrying out a dementia screening on younger subjects. Significantly, 71 subjects in the age group of 50-65 years were flagged for follow-up studies; furthermore, these cases with a potentially early onset of dementia were identified in a primary care setting.
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Affiliation(s)
- Ilka M Rosa
- Neuroscience and Signalling Laboratory, Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
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4
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Wang C, Shou Y, Pan J, Du Y, Liu C, Wang H. The relationship between cholesterol level and Alzheimer’s disease-associated APP proteolysis/Aβ metabolism. Nutr Neurosci 2018; 22:453-463. [DOI: 10.1080/1028415x.2017.1416942] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Chaoqun Wang
- School of Medicine, Hangzhou Normal University, Hangzhou, People’s Republic of China
| | - Yikai Shou
- School of Medicine, Hangzhou Normal University, Hangzhou, People’s Republic of China
| | - Jie Pan
- Department of Endocrinology and Metabolism, 2nd Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, People’s Republic of China
- Institute of Gastroenterology, Zhejiang University, Hangzhou, People’s Republic of China
| | - Yue Du
- School of Medicine, Zhejiang University, Hangzhou, People’s Republic of China
| | - Cuiqing Liu
- College of Basic Medicine, Zhejiang Chinese Medical University, Hangzhou, People’s Republic of China
| | - Huanhuan Wang
- School of Medicine, Hangzhou Normal University, Hangzhou, People’s Republic of China
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Yu CC, Wang Y, Shen F, Kong LH, Wang YW, Zhou H, Tang L. High-frequency (50 Hz) electroacupuncture ameliorates cognitive impairment in rats with amyloid beta 1-42-induced Alzheimer's disease. Neural Regen Res 2018; 13:1833-1841. [PMID: 30136700 PMCID: PMC6128060 DOI: 10.4103/1673-5374.238620] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Acupuncture has been shown to ameliorate cognitive impairment of Alzheimer's disease. Acupoints and stimulation frequency influence the therapeutic effect of electroacupuncture. Rat models of Alzheimer's disease were established by injecting amyloid beta 1–42 (Aβ1–42) into the bilateral lateral ventricles. Electroacupuncture at 2, 30, and 50 Hz was carried out at Baihui (GV20; 15° obliquely to a depth of 2 mm) and Shenshu (BL23; perpendicularly to 4–6 mm depth), once a day for 20 minutes (each), for 15 days, taking a break every 7 days. The Morris water maze test was conducted to assess the learning and memory. The expression levels of glycogen synthase kinase-3β (GSK-3β), pSer9-GSK-3β, pTyr216-GSK-3β, amyloid precursor protein and Aβ1–40 in the hippocampus were determined by western blot assay. Results demonstrated that electroacupuncture treatment at different frequencies markedly improved learning and memory ability, increased synaptic curvatures, decreased the width of synaptic clefts, thickened postsynaptic densities, and downregulated the expression of GSK-3β, amyloid precursor protein, and Aβ1–40. pSer9-GSK-3β expression markedly decreased, while pTyr216-GSK-3β expression increased. High-frequency (50 Hz) electroacupuncture was more effective than low (2 Hz) or medium-frequency (30 Hz) electroacupuncture. In conclusion, electroacupuncture treatment exerts a protective effect against Aβ1–42-induced learning and memory deficits and synapse-ultrastructure impairment via inhibition of GSK-3β activity. Moreover, high-frequency electroacupuncture was the most effective therapy.
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Affiliation(s)
- Chao-Chao Yu
- Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Ying Wang
- Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Feng Shen
- Department of Acupuncture and Moxibustion, College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Li-Hong Kong
- Department of Acupuncture and Moxibustion, College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Ya-Wen Wang
- Department of Acupuncture and Moxibustion, College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Hua Zhou
- Department of Acupuncture and Moxibustion, College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Lei Tang
- Department of Rehabilitation, Wuhan Central Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
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Dias RA, Gonçalves BP, da Rocha JF, da Cruz E Silva OAB, da Silva AMF, Vieira SI. NeuronRead, an open source semi-automated tool for morphometric analysis of phase contrast and fluorescence neuronal images. Mol Cell Neurosci 2017; 85:57-69. [PMID: 28847569 DOI: 10.1016/j.mcn.2017.08.002] [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: 03/13/2017] [Revised: 07/07/2017] [Accepted: 08/10/2017] [Indexed: 11/30/2022] Open
Abstract
Neurons are specialized cells of the Central Nervous System whose function is intricately related to the neuritic network they develop to transmit information. Morphological evaluation of this network and other neuronal structures is required to establish relationships between neuronal morphology and function, and may allow monitoring physiological and pathophysiologic alterations. Fluorescence-based microphotographs are the most widely used in cellular bioimaging, but phase contrast (PhC) microphotographs are easier to obtain, more affordable, and do not require invasive, complicated and disruptive techniques. Despite the various freeware tools available for fluorescence-based images analysis, few exist that can tackle the more elusive and harder-to-analyze PhC images. To surpass this, an interactive semi-automated image processing workflow was developed to easily extract relevant information (e.g. total neuritic length, average cell body area) from both PhC and fluorescence neuronal images. This workflow, named 'NeuronRead', was developed in the form of an ImageJ macro. Its robustness and adaptability were tested and validated on rat cortical primary neurons under control and differentiation inhibitory conditions. Validation included a comparison to manual determinations and to a golden standard freeware tool for fluorescence image analysis. NeuronRead was subsequently applied to PhC images of neurons at distinct differentiation days and exposed or not to DAPT, a pharmacological inhibitor of the γ-secretase enzyme, which cleaves the well-known Alzheimer's amyloid precursor protein (APP) and the Notch receptor. Data obtained confirms a neuritogenic regulatory role for γ-secretase products and validates NeuronRead as a time- and cost-effective useful monitoring tool.
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Affiliation(s)
- Roberto A Dias
- Cell Differentiation and Regeneration group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, Universidade de Aveiro, Aveiro, Portugal; Neurosciences and Signalling group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, Universidade de Aveiro, Aveiro, Portugal
| | - Bruno P Gonçalves
- Cell Differentiation and Regeneration group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, Universidade de Aveiro, Aveiro, Portugal; Neurosciences and Signalling group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, Universidade de Aveiro, Aveiro, Portugal
| | - Joana F da Rocha
- Cell Differentiation and Regeneration group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, Universidade de Aveiro, Aveiro, Portugal; Neurosciences and Signalling group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, Universidade de Aveiro, Aveiro, Portugal
| | - Odete A B da Cruz E Silva
- Neurosciences and Signalling group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, Universidade de Aveiro, Aveiro, Portugal
| | - Augusto M F da Silva
- Instituto de Engenharia Electrónica e Telemática (IEETA), Departamento de Electrónica e Telecomunicações (DETI), Universidade de Aveiro, Aveiro, Portugal
| | - Sandra I Vieira
- Cell Differentiation and Regeneration group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, Universidade de Aveiro, Aveiro, Portugal; Neurosciences and Signalling group, Institute of Biomedicine (iBiMED), Department of Medical Sciences, Universidade de Aveiro, Aveiro, Portugal.
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7
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Oliveira J, Costa M, de Almeida MSC, da Cruz e Silva OA, Henriques AG. Protein Phosphorylation is a Key Mechanism in Alzheimer’s Disease. J Alzheimers Dis 2017; 58:953-978. [DOI: 10.3233/jad-170176] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Joana Oliveira
- Department of Medical Sciences, Neuroscience and Signalling Laboratory, iBiMED, University of Aveiro, Aveiro, Portugal
| | - Márcio Costa
- Department of Medical Sciences, Neuroscience and Signalling Laboratory, iBiMED, University of Aveiro, Aveiro, Portugal
| | | | - Odete A.B. da Cruz e Silva
- Department of Medical Sciences, Neuroscience and Signalling Laboratory, iBiMED, University of Aveiro, Aveiro, Portugal
| | - Ana Gabriela Henriques
- Department of Medical Sciences, Neuroscience and Signalling Laboratory, iBiMED, University of Aveiro, Aveiro, Portugal
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8
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Zhang N, He L, Feng H, Kong Y, Wang J, Zhang J. RETRACTED ARTICLE: Complex Effect of RNA Spliceosome Inhibition on Amyloid Precursor Protein Expression. Neurochem Res 2016; 41:3417. [DOI: 10.1007/s11064-016-1993-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 06/17/2016] [Accepted: 06/23/2016] [Indexed: 11/24/2022]
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9
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Altered protein phosphorylation as a resource for potential AD biomarkers. Sci Rep 2016; 6:30319. [PMID: 27466139 PMCID: PMC4964585 DOI: 10.1038/srep30319] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 07/04/2016] [Indexed: 01/19/2023] Open
Abstract
The amyloidogenic peptide, Aβ, provokes a series of events affecting distinct cellular pathways regulated by protein phosphorylation. Aβ inhibits protein phosphatases in a dose-dependent manner, thus it is expected that the phosphorylation state of specific proteins would be altered in response to Aβ. In fact several Alzheimer’s disease related proteins, such as APP and TAU, exhibit pathology associated hyperphosphorylated states. A systems biology approach was adopted and the phosphoproteome, of primary cortical neuronal cells exposed to Aβ, was evaluated. Phosphorylated proteins were recovered and those whose recovery increased or decreased, upon Aβ exposure across experimental sets, were identified. Significant differences were evident for 141 proteins and investigation of their interactors revealed key protein clusters responsive to Aβ treatment. Of these, 73 phosphorylated proteins increased and 68 decreased upon Aβ addition. These phosphorylated proteins represent an important resource of potential AD phospho biomarkers that should be further pursued.
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Martins F, Rebelo S, Santos M, Cotrim CZ, da Cruz e Silva EF, da Cruz e Silva OAB. BRI2 and BRI3 are functionally distinct phosphoproteins. Cell Signal 2015; 28:130-44. [PMID: 26515131 DOI: 10.1016/j.cellsig.2015.10.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/24/2015] [Indexed: 01/21/2023]
Abstract
Three BRI protein family members have been identified. Among these are BRI3 and BRI2, the latter is associated with Familial Danish and Familial British dementias. 'In silico' sequence analysis identified putative PP1 binding sites in BRI2 and BRI3. This is singularly important, given that protein phosphorylation is a major mechanism regulating intracellular processes. Protein phosphatase 1 (PP1) interacting proteins (PIPs) are fundamental in determining substrate specificity and subcellular localization of this phosphatase. More than 200 PIPs have thus far been reported. Both BRI2 and BRI3 are type II transmembrane glycoproteins relevant in neuronal systems. Using Myc-BRI2 and Myc-BRI3, wild type and PP1 binding mutant constructs, it was possible to show, for the first time, that in fact BRI2 and BRI3 bind PP1. The complexes BRI2:PP1 and BRI3:PP1 were validated in vitro and in vivo. The subcellular distribution of BRI2 and BRI3 is similar; both localize to the perinuclear area and Golgi apparatus in non-neuronal cells. However, in SH-SY5Y cells, BRI2 and BRI3 could also be detected in elongated cellular projections ('processes') and in rat cortical neurons both are broadly distributed throughout the cell body, neuritis and the nucleus. Consistently, co-localization of BRI2 and BRI3 with PP1 was evident. The functional significance of these complexes is apparent given that both BRI proteins are substrates of PP1, thus simultaneously this is the first report of BRI2 and BRI3 as phosphoproteins. Moreover, we show that when BRI2 is phosphorylated a significant increase in neuronal outgrowth and differentiation is evident. Interestingly, the Alzheimer's amyloid precursor protein (APP), forms a trimeric complex composed of PP1 and Fe65, with PP1 having the capacity to dephosphorylate APP at Thr668 residue. The emerging consensus appears to be that PP1 containing complexes are crucial in regulating signaling events underlying neuropathological conditions.
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Affiliation(s)
- Filipa Martins
- Laboratório de Neurociências e Sinalização Celular, Centro de Biologia Celular, iBiMED, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - Sandra Rebelo
- Laboratório de Neurociências e Sinalização Celular, Centro de Biologia Celular, iBiMED, SACS, Universidade de Aveiro, Aveiro, Portugal.
| | - Mariana Santos
- Laboratório de Neurociências e Sinalização Celular, Centro de Biologia Celular, iBiMED, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - Cândida Zita Cotrim
- Laboratório de Neurociências e Sinalização Celular, Centro de Biologia Celular, iBiMED, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - Edgar F da Cruz e Silva
- Laboratório de Neurociências e Sinalização Celular, Centro de Biologia Celular, iBiMED, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - Odete A B da Cruz e Silva
- Laboratório de Neurociências e Sinalização Celular, Centro de Biologia Celular, iBiMED, SACS, Universidade de Aveiro, Aveiro, Portugal
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11
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Genetic mutations strengthen functional association of LAP1 with DYT1 dystonia and muscular dystrophy. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2015; 766:42-7. [DOI: 10.1016/j.mrrev.2015.07.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Revised: 07/30/2015] [Accepted: 07/31/2015] [Indexed: 12/30/2022]
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12
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da Rocha JF, da Cruz e Silva OAB, Vieira SI. Analysis of the amyloid precursor protein role in neuritogenesis reveals a biphasic SH-SY5Y neuronal cell differentiation model. J Neurochem 2015; 134:288-301. [DOI: 10.1111/jnc.13133] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 03/17/2015] [Accepted: 04/16/2015] [Indexed: 01/04/2023]
Affiliation(s)
- Joana Fernandes da Rocha
- Laboratório de Neurociências e Sinalização Celular; CBC and iBiMED; Secção Autónoma de Ciências da Saúde; Universidade de Aveiro; Aveiro Portugal
| | - Odete A. B. da Cruz e Silva
- Laboratório de Neurociências e Sinalização Celular; CBC and iBiMED; Secção Autónoma de Ciências da Saúde; Universidade de Aveiro; Aveiro Portugal
| | - Sandra Isabel Vieira
- Laboratório de Neurociências e Sinalização Celular; CBC and iBiMED; Secção Autónoma de Ciências da Saúde; Universidade de Aveiro; Aveiro Portugal
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Henriques AG, Oliveira JM, Carvalho LP, da Cruz E Silva OAB. Aβ Influences Cytoskeletal Signaling Cascades with Consequences to Alzheimer's Disease. Mol Neurobiol 2014; 52:1391-1407. [PMID: 25344315 DOI: 10.1007/s12035-014-8913-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 09/28/2014] [Indexed: 01/16/2023]
Abstract
Abnormal signal transduction events can impact upon the cytoskeleton, affecting the actin and microtubule networks with direct relevance to Alzheimer's disease (AD). Cytoskeletal anomalies, in turn, promote atypical neuronal responses, with consequences for cellular organization and function. Neuronal cytoskeletal modifications in AD include neurofibrillary tangles, which result from aggregates of hyperphosphorylated tau protein. The latter is a microtubule (MT)-binding protein, whose abnormal phosphorylation leads to MT instability and consequently provokes irregularities in the neuronal trafficking pathways. Early stages of AD are also characterized by synaptic dysfunction and loss of dendritic spines, which correlate with cognitive deficit and impaired brain function. Actin dynamics has a prominent role in maintaining spine plasticity and integrity, thus providing the basis for memory and learning processes. Hence, factors that disrupt both actin and MT network dynamics will compromise neuronal function and survival. The peptide Aβ is the major component of senile plaques and has been described as a pivotal mediator of neuronal dystrophy and synaptic loss in AD. Here, we review Aβ-mediated effects on both MT and actin networks and focus on the relevance of the elicited cytoskeletal signaling events targeted in AD pathology.
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Affiliation(s)
- Ana Gabriela Henriques
- Laboratório de Neurociências e Sinalização, Centro de Biologia Celular, SACS, Universidade de Aveiro, 3810-193, Aveiro, Portugal
| | - Joana Machado Oliveira
- Laboratório de Neurociências e Sinalização, Centro de Biologia Celular, SACS, Universidade de Aveiro, 3810-193, Aveiro, Portugal
| | - Liliana Patrícia Carvalho
- Laboratório de Neurociências e Sinalização, Centro de Biologia Celular, SACS, Universidade de Aveiro, 3810-193, Aveiro, Portugal
| | - Odete A B da Cruz E Silva
- Laboratório de Neurociências e Sinalização, Centro de Biologia Celular, SACS, Universidade de Aveiro, 3810-193, Aveiro, Portugal.
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Durairajan SSK, Huang YY, Yuen PY, Chen LL, Kwok KY, Liu LF, Song JX, Han QB, Xue L, K. Chung S, Huang JD, Baum L, Senapati S, Li M. Effects of Huanglian-Jie-Du-Tang and its modified formula on the modulation of amyloid-β precursor protein processing in Alzheimer's disease models. PLoS One 2014; 9:e92954. [PMID: 24671102 PMCID: PMC3966845 DOI: 10.1371/journal.pone.0092954] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 02/27/2014] [Indexed: 01/23/2023] Open
Abstract
Huanglian-Jie-Du-Tang (HLJDT) is a famous traditional Chinese herbal formula that has been widely used clinically to treat cerebral ischemia. Recently, we found that berberine, a major alkaloid compound in HLJDT, reduced amyloid-β (Aβ) accumulation in an Alzheimer’s disease (AD) mouse model. In this study, we compared the effects of HLJDT, four single component herbs of HLJDT (Rhizoma coptidis (RC), Radix scutellariae (RS), Cortex phellodendri (CP) and Fructus gardenia (FG)) and the modified formula of HLJDT (HLJDT-M, which is free of RS) on the regulatory processing of amyloid-β precursor protein (APP) in an in vitro model of AD. Here we show that treatment with HLJDT-M and its components RC, CP, and the main compound berberine on N2a mouse neuroblastoma cells stably expressing human APP with the Swedish mutation (N2a-SwedAPP) significantly decreased the levels of full-length APP, phosphorylated APP at threonine 668, C-terminal fragments of APP, soluble APP (sAPP)-α and sAPPβ-Swedish and reduced the generation of Aβ peptide in the cell lysates of N2a-SwedAPP. HLJDT-M showed more significant APP- and Aβ- reducing effects than berberine, RC or CP treatment alone. In contrast, HLJDT, its component RS and the main active compound of RS, baicalein, strongly increased the levels of all the metabolic products of APP in the cell lysates. The extract from FG, however, did not influence APP modulation. Interestingly, regular treatment of TgCRND8 APP transgenic mice with baicalein exacerbated the amyloid plaque burden, APP metabolism and Aβ production. Taken together, these data provide convincing evidence that HLJDT and baicalein treatment can increase the amyloidogenic metabolism of APP which is at least partly responsible for the baicalein-mediated Aβ plaque increase in the brains of TgCRND8 mice. On the other hand, HLJDT-M significantly decreased all the APP metabolic products including Aβ. Further study of HLJDT-M for therapeutic use in treating AD is warranted.
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Affiliation(s)
- Siva Sundara Kumar Durairajan
- Neuroscience Research Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
- * E-mail: (SSKD); (ML)
| | - Ying-Yu Huang
- Neuroscience Research Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Pui-Yee Yuen
- Neuroscience Research Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Lei-Lei Chen
- Neuroscience Research Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Ka-Yan Kwok
- Natural Products Chemistry & Analysis Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Liang-Feng Liu
- Neuroscience Research Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Ju-Xian Song
- Neuroscience Research Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Quan-Bin Han
- Natural Products Chemistry & Analysis Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Lei Xue
- Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Sookja K. Chung
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Jian-Dong Huang
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Larry Baum
- School of Pharmacy, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Sanjib Senapati
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India
| | - Min Li
- Neuroscience Research Laboratory, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
- * E-mail: (SSKD); (ML)
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15
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Henriques AG, Oliveira JM, Gomes B, Ruivo R, da Cruz e Silva EF, da Cruz e Silva OAB. Complexing Aβ prevents the cellular anomalies induced by the Peptide alone. J Mol Neurosci 2014; 53:661-8. [PMID: 24599756 PMCID: PMC4112052 DOI: 10.1007/s12031-014-0233-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/10/2014] [Indexed: 12/01/2022]
Abstract
Retention of intracellular secreted APP (isAPP) can be provoked by the neurotoxic peptide Aβ. The latter decreases in the cerebrospinal fluid of Alzheimer’s disease (AD) patients, as a consequence of its cerebral accumulation and deposition into senile plaques. Of similar relevance, secreted APP (sAPP) levels can be associated with AD. The studies here presented, reinforce the link between sAPP and Aβ and address putative therapeutic strategies. Laminin and gelsolin are potential candidates; both prevent Aβ fibril formation by complexing with Aβ, thus attenuating its neurotoxicity. We show that preincubation of Aβ with laminin and gelsolin has the effect of rendering it less potent to isAPP accumulation in cortical neurons. This appears to be related to a decrease in F-actin polymerization, whereas Aβ alone induces the polymerization. Further, Aβ decreases gelsolin levels, and the latter is involved in Aβ removal. Our data indicates that Aβ-laminin and Aβ-gelsolin complexes are less neurotoxic and also less potent than fibrillar Aβ at inducing isAPP retention. These results validate the potential of these proteins as therapeutic strategies that prevent the Aβ-induced effects. In hence, given that Aβ decreases the levels of proteins involved in its own clearance, this may contribute to the mechanisms underlying AD pathology.
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Affiliation(s)
- A. G. Henriques
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - J. M. Oliveira
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - B. Gomes
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - R. Ruivo
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - E. F. da Cruz e Silva
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
| | - O. A. B. da Cruz e Silva
- Laboratório de Neurociências, Centro de Biologia Celular, SACS, Universidade de Aveiro, Aveiro, Portugal
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16
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Baptista FI, Henriques AG, Silva AMS, Wiltfang J, da Cruz e Silva OAB. Flavonoids as therapeutic compounds targeting key proteins involved in Alzheimer's disease. ACS Chem Neurosci 2014; 5:83-92. [PMID: 24328060 DOI: 10.1021/cn400213r] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Alzheimer's disease is characterized by pathological aggregation of protein tau and amyloid-β peptides, both of which are considered to be toxic to neurons. Naturally occurring dietary flavonoids have received considerable attention as alternative candidates for Alzheimer's therapy taking into account their antiamyloidogenic, antioxidative, and anti-inflammatory properties. Experimental evidence supports the hypothesis that certain flavonoids may protect against Alzheimer's disease in part by interfering with the generation and assembly of amyloid-β peptides into neurotoxic oligomeric aggregates and also by reducing tau aggregation. Several mechanisms have been proposed for the ability of flavonoids to prevent the onset or to slow the progression of the disease. Some mechanisms include their interaction with important signaling pathways in the brain like the phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinase pathways that regulate prosurvival transcription factors and gene expression. Other processes include the disruption of amyloid-β aggregation and alterations in amyloid precursor protein processing through the inhibition of β-secretase and/or activation of α-secretase, and inhibiting cyclin-dependent kinase-5 and glycogen synthase kinase-3β activation, preventing abnormal tau phosphorylation. The interaction of flavonoids with different signaling pathways put forward their therapeutic potential to prevent the onset and progression of Alzheimer's disease and to promote cognitive performance. Nevertheless, further studies are needed to give additional insight into the specific mechanisms by which flavonoids exert their potential neuroprotective actions in the brain of Alzheimer's disease patients.
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Affiliation(s)
- Filipa I. Baptista
- Laboratory
of Neurosciences, Centre for Cell Biology, Health Sciences Department
and Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Ana G. Henriques
- Laboratory
of Neurosciences, Centre for Cell Biology, Health Sciences Department
and Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Artur M. S. Silva
- Department of Chemistry & QOPNA, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Jens Wiltfang
- Department
of Psychiatry and Psychotherapy, University Medicine Göttingen, 37075 Göttingen, Germany
| | - Odete A. B. da Cruz e Silva
- Laboratory
of Neurosciences, Centre for Cell Biology, Health Sciences Department
and Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
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17
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Medina M, Avila J. Understanding the relationship between GSK-3 and Alzheimer’s disease: a focus on how GSK-3 can modulate synaptic plasticity processes. Expert Rev Neurother 2014; 13:495-503. [DOI: 10.1586/ern.13.39] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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18
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Long-term treadmill exercise inhibits the progression of Alzheimer's disease-like neuropathology in the hippocampus of APP/PS1 transgenic mice. Behav Brain Res 2013; 256:261-72. [DOI: 10.1016/j.bbr.2013.08.008] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/01/2013] [Accepted: 08/05/2013] [Indexed: 11/22/2022]
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19
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Luan K, Rosales JL, Lee KY. Viewpoint: Crosstalks between neurofibrillary tangles and amyloid plaque formation. Ageing Res Rev 2013; 12:174-81. [PMID: 22728532 DOI: 10.1016/j.arr.2012.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 05/17/2012] [Accepted: 06/06/2012] [Indexed: 12/29/2022]
Abstract
Since its discovery, the hallmarks of Alzheimer's disease (AD) brain have been recognised as the formation of amyloid plaques and neurofibrillary tangles (NFTs). Mounting evidence has suggested the active interplay between the two pathways. Studies have shown that β-amyloid (Aβ) can be internalized and generated intracellularly, accelerating NFT formation. Conversely, tau elements in NFTs are observed to affect Aβ and amyloid plaque formation. Yet the precise mechanisms which link the pathologies of the two brain lesions remain elusive. In this review, we discuss recent evidence that support five putative mechanisms by which crosstalk occurs between amyloid plaque and NFT formation in AD pathogenesis. Understanding the crosstalks in the formation of AD pathologies could provide new clues for the development of novel therapeutic strategies to delay or halt the progression of AD.
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Affiliation(s)
- Kailie Luan
- Department of Cell Biology and Anatomy, Southern Alberta Cancer Research and Hotchkiss Brain Institutes, University of Calgary, Alberta, Canada
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20
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Nogalska A, D'Agostino C, Engel WK, Askanas V. Activation of the γ-secretase complex and presence of γ-secretase-activating protein may contribute to Aβ42 production in sporadic inclusion-body myositis muscle fibers. Neurobiol Dis 2012; 48:141-9. [PMID: 22750528 DOI: 10.1016/j.nbd.2012.06.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 05/22/2012] [Accepted: 06/22/2012] [Indexed: 01/07/2023] Open
Abstract
The muscle-fiber phenotype of sporadic inclusion-body myositis (s-IBM), the most common muscle disease associated with aging, shares several pathological abnormalities with Alzheimer disease (AD) brain, including accumulation of amyloid-β 42 (Aβ42) and its cytotoxic oligomers. The exact mechanisms leading to Aβ42 production within s-IBM muscle fibers are not known. Aβ42 and Aβ40 are generated after the amyloid-precursor protein (AβPP) is cleaved by β-secretase and the γ-secretase complex. Aβ42 is considered more cytotoxic than Aβ40, and it has a higher propensity to oligomerize, form amyloid fibrils, and aggregate. Recently, we have demonstrated in cultured human muscle fibers that experimental inhibition of lysosomal enzyme activities leads to Aβ42 oligomerization. In s-IBM muscle, we here demonstrate prominent abnormalities of the γ-secretase complex, as evidenced by: a) increase of γ-secretase components, namely active presenilin 1, presenilin enhancer 2, nicastrin, and presence of its mature, glycosylated form; b) increase of mRNAs of these γ-secretase components; c) increase of γ-secretase activity; d) presence of an active form of a newly-discovered γ-secretase activating protein (GSAP); and e) increase of GSAP mRNA. Furthermore, we demonstrate that experimental inhibition of lysosomal autophagic enzymes in cultured human muscle fibers a) activates γ-secretase, and b) leads to posttranslational modifications of AβPP and increase of Aβ42. Since autophagy is impaired in biopsied s-IBM muscle, the same mechanism might be responsible for its having increased γ-secretase activity and Aβ42 production. Accordingly, improving lysosomal function might be a therapeutic strategy for s-IBM patients.
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Affiliation(s)
- Anna Nogalska
- USC Neuromuscular Center, Department of Neurology, University of Southern California Keck School of Medicine, Good Samaritan Hospital, Los Angeles, CA 90017‐1912, USA
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21
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Mackinnon JC, Huether P, Kalisch BE. Effects of nerve growth factor and nitric oxide synthase inhibitors on amyloid precursor protein mRNA levels and protein stability. Open Biochem J 2012; 6:31-9. [PMID: 22550546 PMCID: PMC3339428 DOI: 10.2174/1874091x01206010031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 01/05/2012] [Accepted: 01/10/2012] [Indexed: 12/25/2022] Open
Abstract
We determined previously that nitric oxide (NO) modulates the nerve growth factor (NGF)-mediated increases in amyloid precursor protein (APP) levels in PC12 cells. To elucidate potential mechanisms, the effects of NGF and NO synthase (NOS) inhibitors on APP mRNA levels and protein stability were evaluated. Surprisingly, treatment of PC12 cells with NGF resulted in decreased levels of APP695 and APP751/770 mRNA. Therefore, the effect of NGF on APP protein stability was examined using the translation inhibitor, cycloheximide. Under these conditions, NGF did not alter the rate of APP degradation, suggesting that NGF may be enhancing the translation rate of APP. Since NOS inhibitors attenuate the NGF-mediated increase in APP levels, their effect on APP mRNA levels and protein stability was also assessed. S-methylisothiourea (S-MIU), selective for inducible NOS, decreased both APP695 and APP751/770 mRNA levels while the non-selective NOS inhibitor, N(ω)-nitro-L-arginine methylester (L-NAME) had no effect. In both control and NGF-treated PC12 cells, S-MIU increased the half-life of APP, with the greatest effect observed with the APP695 isoform. Based on these data we propose that in PC12 cells, NGF increases APP levels through enhanced translation rate and that NO, which modulates the NGF-induced increase in APP protein, also regulates APP mRNA levels and could play a role in APP processing.
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Affiliation(s)
- Janet C Mackinnon
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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22
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Durairajan SSK, Liu LF, Lu JH, Chen LL, Yuan Q, Chung SK, Huang L, Li XS, Huang JD, Li M. Berberine ameliorates β-amyloid pathology, gliosis, and cognitive impairment in an Alzheimer's disease transgenic mouse model. Neurobiol Aging 2012; 33:2903-19. [PMID: 22459600 DOI: 10.1016/j.neurobiolaging.2012.02.016] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 02/15/2012] [Indexed: 12/25/2022]
Abstract
The accumulation of β-amyloid (Aβ) peptide derived from abnormal processing of amyloid precursor protein (APP) is a common pathological hallmark of Alzheimer's disease (AD) brains. In this study, we evaluated the therapeutic effect of berberine (BBR) extracted from Coptis chinensis Franch, a Chinese medicinal herb, on the neuropathology and cognitive impairment in TgCRND8 mice, a well established transgenic mouse model of AD. Two-month-old TgCRND8 mice received a low (25 mg/kg per day) or a high dose of BBR (100 mg/kg per day) by oral gavage until 6 months old. BBR treatment significantly ameliorated learning deficits, long-term spatial memory retention, as well as plaque load compared with vehicle control treatment. In addition, enzyme-linked immunosorbent assay (ELISA) measurement showed that there was a profound reduction in levels of detergent-soluble and -insoluble β-amyloid in brain homogenates of BBR-treated mice. Glycogen synthase kinase (GSK)3, a major kinase involved in APP and tau phosphorylation, was significantly inhibited by BBR treatment. We also found that BBR significantly decreased the levels of C-terminal fragments of APP and the hyperphosphorylation of APP and tau via the Akt/glycogen synthase kinase 3 signaling pathway in N2a mouse neuroblastoma cells stably expressing human Swedish mutant APP695 (N2a-SwedAPP). Our results suggest that BBR provides neuroprotective effects in TgCRND8 mice through regulating APP processing and that further investigation of the BBR for therapeutic use in treating AD is warranted.
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23
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Neurodegeneration in Alzheimer disease: role of amyloid precursor protein and presenilin 1 intracellular signaling. J Toxicol 2012; 2012:187297. [PMID: 22496686 PMCID: PMC3306972 DOI: 10.1155/2012/187297] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 10/14/2011] [Accepted: 10/26/2011] [Indexed: 01/02/2023] Open
Abstract
Alzheimer disease (AD) is a heterogeneous neurodegenerative disorder characterized by (1) progressive loss of synapses and neurons, (2) intracellular neurofibrillary tangles, composed of hyperphosphorylated Tau protein, and (3) amyloid plaques. Genetically, AD is linked to mutations in few proteins amyloid precursor protein (APP) and presenilin 1 and 2 (PS1 and PS2). The molecular mechanisms underlying neurodegeneration in AD as well as the physiological function of APP are not yet known. A recent theory has proposed that APP and PS1 modulate intracellular signals to induce cell-cycle abnormalities responsible for neuronal death and possibly amyloid deposition. This hypothesis is supported by the presence of a complex network of proteins, clearly involved in the regulation of signal transduction mechanisms that interact with both APP and PS1. In this review we discuss the significance of novel finding related to cell-signaling events modulated by APP and PS1 in the development of neurodegeneration.
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24
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Braithwaite SP, Stock JB, Lombroso PJ, Nairn AC. Protein phosphatases and Alzheimer's disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 106:343-79. [PMID: 22340724 PMCID: PMC3739963 DOI: 10.1016/b978-0-12-396456-4.00012-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alzheimer's Disease (AD) is characterized by progressive loss of cognitive function, linked to marked neuronal loss. Pathological hallmarks of the disease are the accumulation of the amyloid-β (Aβ) peptide in the form of amyloid plaques and the intracellular formation of neurofibrillary tangles (NFTs). Accumulating evidence supports a key role for protein phosphorylation in both the normal and pathological actions of Aβ as well as the formation of NFTs. NFTs contain hyperphosphorylated forms of the microtubule-binding protein tau, and phosphorylation of tau by several different kinases leads to its aggregation. The protein kinases involved in the generation and/or actions of tau or Aβ are viable drug targets to prevent or alleviate AD pathology. However, it has also been recognized that the protein phosphatases that reverse the actions of these protein kinases are equally important. Here, we review recent advances in our understanding of serine/threonine and tyrosine protein phosphatases in the pathology of AD.
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25
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Abstract
Alzheimer's disease ranks the first cause for senile dementia. The amyloid cascade is proposed to contribute to the pathogenesis of this disease. In this cascade, amyloid β peptide (Aβ) is produced through a sequential cleavage of amyloid precursor protein (APP) by β and γ secretases, while its cleavage by α secretase precludes Aβ production and generates neurotrophic sAPPα. Thus, enhancing α secretase activity or suppressing β and γ cleavage may reduce Aβ formation and ameliorate the pathological process of the disease. Several regulatory mechanisms of APP cleavage have been established. The present review mainly summarizes the signaling pathways pertinent to the regulation of APP β cleavage.
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Affiliation(s)
- Jun-Feng Wang
- Laboratory of Neural Signal Transduction, Institute of Neuroscience, Shanghai Institutes of Biological Sciences, State Key Laboratory of Neuroscience, Shanghai 200031, China
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26
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Khairallah MI, Kassem LAA. Alzheimer's disease: current status of etiopathogenesis and therapeutic strategies. Pak J Biol Sci 2011; 14:257-272. [PMID: 21870628 DOI: 10.3923/pjbs.2011.257.272] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Alzheimer's Disease (AD) is one of the most common age-related neurodegenerative diseases. It is the most prevalent form of dementia, a general term for memory loss. It is characterized by progressive cognitive dysfunction, various behavioral and neuro-psychiatric disturbances that seriously interfere with daily life. Scientists have identified factors that appear to play a role in the development of AD but no definitive causes have been found for this complex disorder. The pathogenesis of Alzheimer's disease is highly complex. While several pathologies characterize this disease, amyloid plaques and neurofibrillary tangles are hallmark neuropathological lesions in AD brain. Current AD therapies are merely palliative and only temporarily slow cognitive decline and treatments that address the underlying pathologic mechanisms of AD are still lacking. In this review, we focus on the current aspects of AD ranging from the key risk factors for AD, the underlying pathogenic events and the novel medications including disease-modifying properties.
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27
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Schettini G, Govoni S, Racchi M, Rodriguez G. Phosphorylation of APP-CTF-AICD domains and interaction with adaptor proteins: signal transduction and/or transcriptional role--relevance for Alzheimer pathology. J Neurochem 2010; 115:1299-308. [PMID: 21039524 DOI: 10.1111/j.1471-4159.2010.07044.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In recent decades, the study of the amyloid precursor protein (APP) and of its proteolytic products carboxy terminal fragment (CTF), APP intracellular C-terminal domain (AICD) and amyloid beta has been mostly focussed on the role of APP as a producer of the toxic amyloid beta peptide. Here, we reconsider the role of APP suggesting, in a provocative way, the protein as a central player in a putative signalling pathway. We highlight the presence in the cytosolic tail of APP of the YENPTY motif which is typical of tyrosine kinase receptors, the phosphorylation of the tyrosine, serine and threonine residues, the kinases involved and the interaction with intracellular adaptor proteins. In particular, we examine the interaction with Shc and Grb2 regulators, which through the activation of Ras proteins elicit downstream signalling events such as the MAPK pathway. The review also addresses the interaction of APP, CTFs and AICD with other adaptor proteins and in particular with Fe65 for nuclear transcriptional activity and the importance of phosphorylation for sorting the secretases involved in the amyloidogenic or non-amyloidogenic pathways. We provide a novel perspective on Alzheimer's disease pathogenesis, focussing on the perturbation of the physiological activities of APP-CTFs and AICD as an alternative perspective from that which normally focuses on the accumulation of neurotoxic proteolytic fragments.
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Affiliation(s)
- Gennaro Schettini
- Department of Oncology, Biology and Genetics, University of Genova, Genova, Italy.
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28
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A free radical-generating system regulates APP metabolism/processing. FEBS Lett 2010; 584:4611-8. [PMID: 20965178 DOI: 10.1016/j.febslet.2010.10.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 10/13/2010] [Indexed: 01/28/2023]
Abstract
Oxidative stress, a risk factor in the pathophysiology of Alzheimer's disease, is intimately associated with aging. We previously reported that the X-XOD free radical generating system acts as a modulator of lipid metabolism and a mild inducer of apoptotic death. Using the same cell model, the present study examines the metabolism/processing of the amyloid precursor protein (APP). Prior to inducing cell death, X-XOD promoted the secretion of α-secretase-cleaved soluble APP (sAPPα) and increased the level of APP carboxy-terminal fragments produced by α and γ secretase (αCTF and γCTF/AICD). In contrast, it reduced the activity of β-secretase and the level of secreted Aβ. The present results indicate that mild oxidative stress maintained throughout culturing regulates APP metabolism/processing in SK-N-MC human neuroblastoma cells.
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29
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Ploia C, Sclip A, Colombo A, Repici M, Gardoni F, Di Luca M, Forloni G, Antoniou X, Borsello T. Role of Glycogen Synthase Kinase-3β in APP Hyperphosphorylation Induced by NMDA Stimulation in Cortical Neurons. Pharmaceuticals (Basel) 2010; 3:42-58. [PMID: 27713242 PMCID: PMC3991020 DOI: 10.3390/ph3010042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 12/03/2009] [Accepted: 01/05/2010] [Indexed: 01/24/2023] Open
Abstract
The phosphorylation of Amyloid Precursor Protein (APP) at Thr668 plays a key role in APP metabolism that is highly relevant to AD. The c-Jun-N-terminal kinase (JNK), glycogen synthase kinase-3β (GSK-3β) and cyclin-dependent kinase 5 (Cdk5) can all be responsible for this phosphorylation. These kinases are activated by excitotoxic stimuli fundamental hallmarks of AD. The exposure of cortical neurons to a high dose of NMDA (100 μM) for 30’-45’ led to an increase of P-APP Thr668. During NMDA stimulation APP hyperphosphorylation has to be assigned to GSK-3β activity, since addition of L803-mts, a substrate competitive inhibitor of GSK-3β reduced APP phosphorylation induced by NMDA. On the contrary, inhibition of JNK and Cdk5 with D-JNKI1 and Roscovitine respectively did not prevent NMDA-induced P-APP increase. These data show a tight connection, in excitotoxic conditions, between APP metabolism and the GSK-3β signaling pathway.
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Affiliation(s)
- Cristina Ploia
- Istituto di ricerche Farmacologiche "Mario Negri", Via La Masa 19, 20156 Milano, Italy.
| | - Alessandra Sclip
- Istituto di ricerche Farmacologiche "Mario Negri", Via La Masa 19, 20156 Milano, Italy.
| | - Alessio Colombo
- Istituto di ricerche Farmacologiche "Mario Negri", Via La Masa 19, 20156 Milano, Italy.
| | - Mariaelena Repici
- UMR 7102 Neurobiologie des Processus Adaptatifs, Universite P. et M. Curie, 9 quai St Bernard, 75005, Paris, France.
| | - Fabrizio Gardoni
- Dipartimento Scienze Farmacologiche, Università degli Studi di Milano, Via Balzaretti, 9, 20133 Milano, Italy.
| | - Monica Di Luca
- Dipartimento Scienze Farmacologiche, Università degli Studi di Milano, Via Balzaretti, 9, 20133 Milano, Italy.
| | - Gianluigi Forloni
- Istituto di ricerche Farmacologiche "Mario Negri", Via La Masa 19, 20156 Milano, Italy.
| | - Xanthi Antoniou
- Istituto di ricerche Farmacologiche "Mario Negri", Via La Masa 19, 20156 Milano, Italy.
| | - Tiziana Borsello
- Istituto di ricerche Farmacologiche "Mario Negri", Via La Masa 19, 20156 Milano, Italy.
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30
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Terracciano C, Nogalska A, Engel WK, Askanas V. In AbetaPP-overexpressing cultured human muscle fibers proteasome inhibition enhances phosphorylation of AbetaPP751 and GSK3beta activation: effects mitigated by lithium and apparently relevant to sporadic inclusion-body myositis. J Neurochem 2009; 112:389-96. [PMID: 19878439 DOI: 10.1111/j.1471-4159.2009.06461.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Muscle fiber degeneration in sporadic inclusion-body myositis (s-IBM) is characterized by accumulation of multiprotein aggregates, including aggregated amyloid-beta (Abeta)-precursor protein 751 (AbetaPP751), Abeta, phosphorylated tau, and other 'Alzheimer-characteristic' proteins. Proteasome inhibition is an important component of the s-IBM pathogenesis. In brains of Alzheimer's disease (AD) patients and AD transgenic-mouse models, phosphorylation of neuronal AbetaPP695 (p-AbetaPP) on Thr668 (equivalent to T724 of AbetaPP751) is considered detrimental because it increases generation of cytotoxic Abeta and induces tau phosphorylation. Activated glycogen synthase kinase3beta (GSK3beta) is involved in phosphorylation of both AbetaPP and tau. Lithium, an inhibitor of GSK3beta, was reported to reduce levels of both the total AbetaPP and p-AbetaPP in AD animal models. In relation to s-IBM, we now show for the first time that (1) In AbetaPP-overexpressing cultured human muscle fibers (human muscle culture IBM model: (a) proteasome inhibition significantly increases GSK3beta activity and AbetaPP phosphorylation, (b) treatment with lithium decreases (i) phosphorylated-AbetaPP, (ii) total amount of AbetaPP, (iii) Abeta oligomers, and (iv) GSK3beta activity; and (c) lithium improves proteasome function. (2) In biopsied s-IBM muscle fibers, GSK3beta is significantly activated and AbetaPP is phosphorylated on Thr724. Accordingly, treatment with lithium, or other GSK3beta inhibitors, might benefit s-IBM patients.
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Affiliation(s)
- Chiara Terracciano
- Department of Neurology, USC Neuromuscular Center, University of Southern California Keck, School of Medicine, Good Samaritan Hospital, Los Angeles, California 90017, USA
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31
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Alpár A, Naumann N, Ueberham U, Arendt T, Gärtner U. Deprivation-induced dendritic shrinkage might be oppositely affected by the expression of wild-type and mutated human amyloid precursor protein. J Neurosci Res 2009; 87:1813-22. [PMID: 19170186 DOI: 10.1002/jnr.22008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The physiological role of the amyloid precursor protein (APP) and its proteolytic fragments in the brain is associated with neuronal survival, neurite outgrowth, synaptic formation, and neuronal plasticity. However, malregulation of APP processing leads to disordered balance of fragments, which may results in opposite, degenerative neuronal effects. In the present study, we analyzed in vivo effects of the expression of wild-type or mutated human APP on afferent deprivation-induced changes of dendritic morphology. After vibrissectomy, expression of wild-type human APP prevented diameter shrinkage of dendritic segments as well as dendritic rarefaction of apical arbors. In contrast, mutant human APP expression exacerbated degenerative changes of deprived barrel neurons. Degradation of apical arbors was especially pronounced. Results demonstrate for the first time opposite effects of the expression of wild-type and mutated human APP on deprivation-induced dendritic restructuring in vivo.
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Affiliation(s)
- Alán Alpár
- Department of Anatomy, Histology and Embryology, Semmelweis University Medical School, Budapest, Hungary.
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32
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Henriques AG, Vieira SI, Crespo-López ME, Guiomar de Oliveira MA, da Cruz e Silva EF, da Cruz e Silva OA. Intracellular sAPP retention in response to Aβ is mapped to cytoskeleton-associated structures. J Neurosci Res 2009; 87:1449-61. [DOI: 10.1002/jnr.21959] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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33
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Vintém APB, Henriques AG, da Cruz e Silva OA, da Cruz e Silva EF. PP1 inhibition by Aβ peptide as a potential pathological mechanism in Alzheimer's disease. Neurotoxicol Teratol 2009; 31:85-8. [DOI: 10.1016/j.ntt.2008.11.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 11/05/2008] [Accepted: 11/05/2008] [Indexed: 10/21/2022]
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da Cruz e Silva OAB, Rebelo S, Vieira SI, Gandy S, da Cruz e Silva EF, Greengard P. Enhanced generation of Alzheimer's amyloid-beta following chronic exposure to phorbol ester correlates with differential effects on alpha and epsilon isozymes of protein kinase C. J Neurochem 2008; 108:319-30. [PMID: 19012746 DOI: 10.1111/j.1471-4159.2008.05770.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Alzheimer's amyloid precursor protein (APP) sorting and processing are modulated through signal transduction mechanisms regulated by protein phosphorylation. Notably, protein kinase C (PKC) appears to be an important component in signaling pathways that control APP metabolism. PKCs exist in at least 11 conventional and unconventional isoforms, and PKCalpha and PKCepsilon isoforms have been specifically implicated in controlling the generation of soluble APP and amyloid-beta (Abeta) fragments of APP, although identification of the PKC substrate phospho-state-sensitive effector proteins remains challenging. In the current study, we present evidence that chronic application of phorbol esters to cultured cells in serum-free medium is associated with several phenomena, namely: (i) PKCalpha down-regulation; (ii) PKCepsilon up-regulation; (iii) accumulation of APP and/or APP carboxyl-terminal fragments in the trans Golgi network; (iv) disappearance of fluorescence from cytoplasmic vesicles bearing a green fluorescent protein tagged form of APP; (v) insensitivity of soluble APP release following acute additional phorbol application; and (vi) elevated cellular APP mRNA levels and holoprotein, and secreted Abeta. These data indicate that, unlike acute phorbol ester application, which is accompanied by lowered Abeta generation, chronic phorbol ester treatment causes differential regulation of PKC isozymes and increased Abeta generation. These data have implications for the design of amyloid-lowering strategies based on modulating PKC activity.
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Venezia V, Nizzari M, Carlo P, Corsaro A, Florio T, Russo C. Amyloid precursor protein and presenilin involvement in cell signaling. NEURODEGENER DIS 2007; 4:101-11. [PMID: 17596704 DOI: 10.1159/000101834] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
To date the most relevant role for the amyloid precursor protein (APP) and for the presenilins (PSs) on Alzheimer's disease (AD) genesis is linked to the 'amyloid hypothesis', which considers an aberrant formation of amyloid-beta peptides the cause of neurodegeneration. In this view, APP is merely a substrate, cleaved by the gamma-secretase complex to form toxic amyloid peptides, PSs are key players in gamma-secretase complex, and corollary or secondary events are Tau-linked pathology and gliosis. A second theory, complementary to the amyloid hypothesis, proposes that APP and PSs may modulate a yet unclear cell signal, the disruption of which may induce cell-cycle abnormalities, neuronal death, eventually amyloid formation and finally dementia. This hypothesis is supported by the presence of a complex network of proteins, with a clear relevance for signal transduction mechanisms, which interact with APP or PSs. In this scenario, the C-terminal domain of APP has a pivotal role due to the presence of the 682YENPTY687 motif that represents the docking site for multiple interacting proteins involved in cell signaling. In this review we discuss the significance of novel findings related to cell signaling events modulated by APP and PSs for AD development.
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Affiliation(s)
- Valentina Venezia
- Department of Oncology, Biology and Genetics, University of Genova, Genova, Italy
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Rebelo S, Vieira SI, Esselmann H, Wiltfang J, da Cruz e Silva EF, da Cruz e Silva OAB. Tyrosine 687 Phosphorylated Alzheimer’s Amyloid Precursor Protein Is Retained Intracellularly and Exhibits a Decreased Turnover Rate. NEURODEGENER DIS 2007; 4:78-87. [PMID: 17596701 DOI: 10.1159/000101831] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Tyrosine 687 (Y687) of the Alzheimer's amyloid precursor protein (APP) was shown to be phosphorylated in the brains of Alzheimer's disease patients. This residue lies within a typical endocytosis consensus motif commonly found in molecules with receptor functions, strongly suggesting a potential role for APP in signal transduction. Consequently, the work here described addressed how phosphorylation of Y687 may be affecting APP in terms of its proteolytic cleavage and subcellular distribution. Our data show that the APP mutant mimicking constitutive dephosphorylation of Y687 had a faster turnover rate, both in terms of maturation and metabolism, when compared to Wt-APP-GFP and even more so when compared to the mutant mimicking constitutive phosphorylation. Thus, the mutant mimicking constitutively phosphorylated Y687 had a much higher t(1/2) and was significantly retained both in the ER and TGN. Additionally, this mutant was not incorporated into visible vesicular structures, with a concomitant dramatic decrease in Abeta production. Our findings point to the direct phosphorylation of APP on Y687 as an important regulatory mechanism in terms of determining the subcellular localization of APP and modulating its processing via different proteolytic pathways.
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Affiliation(s)
- Sandra Rebelo
- Laboratório de Neurociências, Centro de Biologia Celular, Universidade de Aveiro, Aveiro, Portugal
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Nizzari M, Venezia V, Repetto E, Caorsi V, Magrassi R, Gagliani MC, Carlo P, Florio T, Schettini G, Tacchetti C, Russo T, Diaspro A, Russo C. Amyloid Precursor Protein and Presenilin1 Interact with the Adaptor GRB2 and Modulate ERK 1,2 Signaling. J Biol Chem 2007; 282:13833-44. [PMID: 17314098 DOI: 10.1074/jbc.m610146200] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The amyloid precursor protein (APP) and the presenilins 1 and 2 are genetically linked to the development of familial Alzheimer disease. APP is a single-pass transmembrane protein and precursor of fibrillar and toxic amyloid-beta peptides, which are considered responsible for Alzheimer disease neurodegeneration. Presenilins are multipass membrane proteins, involved in the enzymatic cleavage of APP and other signaling receptors and transducers. The role of APP and presenilins in Alzheimer disease development seems to be related to the formation of amyloid-beta peptides; however, their physiological function, reciprocal interaction, and molecular mechanisms leading to neurodegeneration are unclear. APP and presenilins are also involved in multiple interactions with intracellular proteins, the significance of which is under investigation. Among the different APP-interacting proteins, we focused our interest on the GRB2 adaptor protein, which connects cell surface receptors to intracellular signaling pathways. In this study we provide evidence by co-immunoprecipitation experiments, confocal and electron microscopy, and by fluorescence resonance energy transfer experiments that both APP and presenilin1 interact with GRB2 in vesicular structures at the centrosome of the cell. The final target for these interactions is ERK1,2, which is activated in mitotic centrosomes in a PS1- and APP-dependent manner. These data suggest that both APP and presenilin1 can be part of a common signaling pathway that regulates ERK1,2 and the cell cycle.
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Affiliation(s)
- Mario Nizzari
- Dipartimento di Oncologia, Biologia e Genetica, Università di Genova, Viale Benedetto XV, 2, 16132 Genova, Italy
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Domingues SCTS, Henriques AG, Wu W, Da Cruz e Silva EF, Da Cruz e Silva OAB. Altered subcellular distribution of the Alzheimer's amyloid precursor protein under stress conditions. Ann N Y Acad Sci 2007; 1096:184-95. [PMID: 17405930 DOI: 10.1196/annals.1397.085] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Altered metabolism of the Alzheimer's amyloid precursor protein (APP) appears to be a key event in the pathogenesis of Alzheimer's disease (AD), and both altered phosphorylation and oxidative stress appear to affect the production of the toxic Abeta fragment. Our results show that altered processing of APP was observed under conditions of stress induced by sodium azide in the presence of 2-deoxy-D-glucose (2DG). As previously reported, the production of the secreted fragment of APP (sAPP) was inhibited. Using APP-GFP fusion proteins, we show that 2DG causes the accumulation/delay of APP in the endoplasmic reticulum (ER)/Golgi (G). The 751 isoform accumulated preferentially in the G, whereas the 695 isoform was blocked preferentially at the ER. This effect was augmented in the presence of sodium azide. APP subcellular distribution was also affected at the plasma membrane. The involvement of protein phosphorylation in APP subcellular localization was reinforced by the effect of drugs, such as phorbol 12-myristate 13-acetate (PMA), since APP was completely depleted from the membrane in the presence of 2DG and PMA. Thus, the hypothesis that APP is processed in a phosphorylation-dependent manner and that this may be of clinical relevance appears to hold true even under stress conditions. Our results provide evidence for a role of protein phosphorylation in APP sorting under stress conditions and contribute to the understanding of the molecular basis of AD.
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Affiliation(s)
- Sara C T S Domingues
- Neuroscience Laboratory, Centre for Cell Biology, University of Aveiro, Aveiro, Portugal
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Sontag E, Nunbhakdi-Craig V, Sontag JM, Diaz-Arrastia R, Ogris E, Dayal S, Lentz SR, Arning E, Bottiglieri T. Protein phosphatase 2A methyltransferase links homocysteine metabolism with tau and amyloid precursor protein regulation. J Neurosci 2007; 27:2751-9. [PMID: 17360897 PMCID: PMC6672573 DOI: 10.1523/jneurosci.3316-06.2007] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Alzheimer's disease (AD) neuropathology is characterized by the accumulation of phosphorylated tau and amyloid-beta peptides derived from the amyloid precursor protein (APP). Elevated blood levels of homocysteine are a significant risk factor for many age-related diseases, including AD. Impaired homocysteine metabolism favors the formation of S-adenosylhomocysteine, leading to inhibition of methyltransferase-dependent reactions. Here, we show that incubation of neuroblastoma cells with S-adenosylhomocysteine results in reduced methylation of protein phosphatase 2A (PP2A), a major brain Ser/Thr phosphatase, most likely by inhibiting PP2A methyltransferase (PPMT). PP2A methylation levels are also decreased after ectopic expression of PP2A methylesterase in Neuro-2a (N2a) cells. Reduced PP2A methylation promotes the downregulation of B alpha-containing holoenzymes, thereby affecting PP2A substrate specificity. It is associated with the accumulation of both phosphorylated tau and APP isoforms and increased secretion of beta-secretase-cleaved APP fragments and amyloid-beta peptides. Conversely, incubation of N2a cells with S-adenosylmethionine and expression of PPMT enhance PP2A methylation. This leads to the accumulation of dephosphorylated tau and APP species and increased secretion of neuroprotective alpha-secretase-cleaved APP fragments. Remarkably, hyperhomocysteinemia induced in wild-type and cystathionine-beta-synthase +/- mice by feeding a high-methionine, low-folate diet is associated with increased brain S-adenosylhomocysteine levels, PPMT downregulation, reduced PP2A methylation levels, and tau and APP phosphorylation. We reported previously that downregulation of neuronal PPMT and PP2A methylation occur in affected brain regions from AD patients. The link between homocysteine, PPMT, PP2A methylation, and key CNS proteins involved in AD pathogenesis provides new mechanistic insights into this disorder.
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Affiliation(s)
- Estelle Sontag
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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Rebelo S, Vieira SI, Esselmann H, Wiltfang J, da Cruz e Silva EF, da Cruz e Silva OAB. Tyr687 dependent APP endocytosis and abeta production. J Mol Neurosci 2007; 32:1-8. [PMID: 17873282 DOI: 10.1007/s12031-007-0001-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 11/30/1999] [Accepted: 11/27/2006] [Indexed: 11/29/2022]
Abstract
The neurotoxic Abeta peptide is derived by proteolytic processing from the Alzheimer's amyloid precursor protein (APP), whose short cytoplasmic domain contains several phosphorylatable amino acids. The latter can be phosphorylated 'in vitro' and 'in vivo,' and in some cases phosphorylation appears to be associated with the disease condition. Using APP-GFP fusion proteins to monitor APP processing, the role of Tyr687 was addressed by mimicking its constitutive phosphorylation (Y687E) and dephosphorylation (Y687F). Contrasting effects on subcellular APP distribution were observed. Y687E-APP-GFP was targeted to the membrane but could not be detected in transferrin containing vesicular structures, and exhibited a concomitant and dramatic decrease in Abeta production. In contrast, Y687F-APP-GFP was endocytosed similarly to wild type APP, but was relatively favoured for beta-secretase cleavage. Overall, Tyr687 appears to be a critical residue determining APP targeting and processing via different pathways, including endocytosis and retrograde transport. Significantly, from a disease perspective, mimicking Tyr687 phosphorylation resulted in a hitherto undescribed inhibition of Abeta production. Our results provide novel insights into the role of direct APP phosphorylation on APP targeting, processing and Abeta production.
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Affiliation(s)
- Sandra Rebelo
- Laboratório de Neurociências, Centro de Biologia Celular, Universidade de Aveiro, Aveiro 3810-193, Portugal
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Balastik M, Lim J, Pastorino L, Lu KP. Pin1 in Alzheimer's disease: multiple substrates, one regulatory mechanism? BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1772:422-9. [PMID: 17317113 PMCID: PMC1868500 DOI: 10.1016/j.bbadis.2007.01.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Revised: 01/08/2007] [Accepted: 01/11/2007] [Indexed: 12/27/2022]
Abstract
Presence of neuritic plaques and neurofibrillary tangles in the brain are two neuropathological hallmarks of Alzheimer's disease (AD), although the molecular basis of their coexistence remains elusive. The neurofibrillary tangles are composed of microtubule binding protein Tau, whereas neuritic plaques consist of amyloid-beta peptides derived from amyloid precursor protein (APP). Recently, the peptidyl-prolyl cis/trans isomerase Pin1 has been identified to regulate the function of certain proteins after phosphorylation and to play an important role in cell cycle regulation and cancer development. New data indicate that Pin1 also regulates the function and processing of Tau and APP, respectively, and is important for protecting against age-dependent neurodegeneration. Furthermore, Pin1 is the only gene known so far that, when deleted in mice, can cause both Tau and Abeta-related pathologies in an age-dependent manner, resembling many aspects of human Alzheimer's disease. Moreover, in the human AD brain Pin1 is downregulated or inhibited by oxidative modifications and/or genetic changes. These results suggest that Pin1 deregulation may provide a link between formation of tangles and plaques in AD.
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Affiliation(s)
- Martin Balastik
- Cancer Biology Program, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 77 Ave. Louis Pasteur, Boston, MA 02115, USA
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Binnington JC, Kalisch BE. Nitric oxide synthase inhibitors modulate nerve growth factor-mediated regulation of amyloid precursor protein expression in PC12 cells. J Neurochem 2007; 101:422-33. [PMID: 17402971 DOI: 10.1111/j.1471-4159.2006.04378.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Nerve growth factor (NGF) can regulate nitric oxide synthase (NOS) expression and nitric oxide (NO) can modulate NGF-mediated neurotrophic responses. In this study, the role of NO in NGF-stimulated amyloid precursor protein (APP) levels was studied. PC12 cells were treated with either the non-selective NOS inhibitor N(omega)-nitro-L-arginine methylester (L-NAME) or the inducible NOS selective inhibitor s-methylisothiourea (S-MIU), and the effect on NGF-mediated increases in APP expression was determined. NGF significantly increased total APP protein levels following 96 h of treatment and this increase was prevented in cells pre-treated with S-MIU. Pre-treatment of cells with actinomycin D also blocked this NGF-mediated induction of APP, indicating de novo protein synthesis is necessary. Treatment with NGF increased APP promoter activity; however, this increase was only partially inhibited by pre-treatment with S-MIU and was increased in the presence of L-NAME. This suggests that NO may be modulating other aspects of APP expression in addition to transcription. Inhibition of NGF signaling pathways was also investigated using inhibitors of mitogen-activated protein (MAP) kinase (U0126), Akt (LY294002) and protein kinase C (PKC; U73122 and bisindolylmaleimide 1 (BIS-1)) activation. Inhibition of each of these pathways prevented NGF-mediated increases in APP protein expression; however, only BIS-1 attenuated NGF-mediated increases in promoter activation. This study indicates that NO is involved in the NGF-mediated regulation of APP, in part at the level of APP transcription and could involve the modulation of NGF signal transduction pathways.
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Affiliation(s)
- Janet C Binnington
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada
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Rockenstein E, Torrance M, Adame A, Mante M, Bar-on P, Rose JB, Crews L, Masliah E. Neuroprotective effects of regulators of the glycogen synthase kinase-3beta signaling pathway in a transgenic model of Alzheimer's disease are associated with reduced amyloid precursor protein phosphorylation. J Neurosci 2007; 27:1981-91. [PMID: 17314294 PMCID: PMC6673566 DOI: 10.1523/jneurosci.4321-06.2007] [Citation(s) in RCA: 228] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Accepted: 10/27/2006] [Indexed: 02/07/2023] Open
Abstract
The glycogen synthase kinase-3beta (GSK3beta) pathway plays an important role in mediating neuronal fate and synaptic plasticity. In Alzheimer's disease (AD), abnormal activation of this pathway might play an important role in neurodegeneration, and compounds such as lithium that modulate GSK3beta activity have been shown to reduce amyloid production and tau phosphorylation in amyloid precursor protein (APP) transgenic (tg) mice. However, it is unclear whether regulation of GSK3beta is neuroprotective in APP tg mice. In this context, the main objective of the present study was to determine whether pharmacological or genetic manipulations that block the GSK3beta pathway might ameliorate the neurodegenerative alterations in APP tg mice and to better understand the mechanisms involved. For this purpose, two sets of experiments were performed. First, tg mice expressing mutant human APP under the Thy1 promoter (hAPP tg) were treated with either lithium chloride or saline alone. Second, hAPP tg mice were crossed with GSK3beta tg mice, in which overexpression of this signaling molecule results in a dominant-negative (DN) effect with inhibition of activity. hAPP tg mice that were treated with lithium or that were crossed with DN-GSK3beta tg mice displayed improved performance in the water maze, preservation of the dendritic structure in the frontal cortex and hippocampus, and decreased tau phosphorylation. Moreover, reduced activation of GSK3beta was associated with decreased levels of APP phosphorylation that resulted in decreased amyloid-beta production. In conclusion, the present study showed that modulation of the GSK3beta signaling pathway might also have neuroprotective effects in tg mice by regulating APP maturation and processing and further supports the notion that GSK3beta might be a suitable target for the treatment of AD.
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Affiliation(s)
| | | | | | | | | | | | - Leslie Crews
- Pathology, University of California, San Diego, La Jolla, California 92093
| | - Eliezer Masliah
- Departments of Neurosciences and
- Pathology, University of California, San Diego, La Jolla, California 92093
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Fardilha M, Vieira SI, Barros A, Sousa M, Da Cruz e Silva OAB, Da Cruz e Silva EF. Differential Distribution of Alzheimer's Amyloid Precursor Protein Family Variants in Human Sperm. Ann N Y Acad Sci 2007; 1096:196-206. [PMID: 17405931 DOI: 10.1196/annals.1397.086] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The Alzheimer's amyloid precursor protein (APP) is a type I transmembrane glycoprotein with receptor-like characteristics that originates the Abeta peptide by proteolytic processing. Abeta is potentially cytotoxic and the major component of the cerebral amyloid plaques in Alzheimer's disease (AD) patients. APP is known to be ubiquitously expressed in mammalian cells, with a broad tissue distribution, and Abeta deposition has been reported to occur also in many cells outside the nervous system. Although many putative functions have been suggested for APP, its precise physiological role remains to be elucidated. As several results point to a role of chronic inflammation in AD pathogenesis and suggest that AD might be a systemic disorder, the importance of APP function in non-neuronal cells/tissues has gained increased relevance. Previous studies have shown that amyloid precursor-like protein 2 (APLP2) is highly expressed in testis and sperm, but failed to unambiguously prove the presence of APP itself in mammalian sperm. The use of a battery of available antibodies that detect APP-specific epitopes or epitopes shared with other APP family members, revealed quite distinct distributions in human sperm. Our results are consistent with previous observations of APLP2 in sperm and unequivocally demonstrate the presence of APP itself in human sperm, thus suggesting a putative role for this important protein in sperm function.
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Affiliation(s)
- Margarida Fardilha
- Signal Transduction Laboratory, Centre for Cell Biology, University of Aveiro, Aveiro, Portugal
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Pastorino L, Lu KP. Pathogenic mechanisms in Alzheimer's disease. Eur J Pharmacol 2006; 545:29-38. [PMID: 16904664 DOI: 10.1016/j.ejphar.2006.06.078] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 06/23/2006] [Accepted: 06/27/2006] [Indexed: 01/22/2023]
Abstract
Alzheimer's disease is a progressive neurodegenerative disorder associated with aging and characterized by neurofibrillary tangles and amyloid plaques that deposit in the brain, triggering the neurodegenerative phenomena and leading to neuronal death. Amyloid plaques are primarily composed of beta-amyloid peptides, which derive from the Amyloid Precursor Protein (APP) upon the consequential action of beta- and gamma-secretase. This review discusses recent literature on beta- and gamma-secretase, and on those cellular factors, like cholesterol and phosphorylation of APP, that are involved in aging and may affect the function of both beta- and gamma-secretase.
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Affiliation(s)
- Lucia Pastorino
- Cancer Biology Program, Beth Israel Deaconess Medical Center, Harvard Medical School, 77 Ave. Louis Pasteur, Boston, MA 02115, USA.
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Rockenstein E, Torrance M, Mante M, Adame A, Paulino A, Rose JB, Crews L, Moessler H, Masliah E. Cerebrolysin decreases amyloid-beta production by regulating amyloid protein precursor maturation in a transgenic model of Alzheimer's disease. J Neurosci Res 2006; 83:1252-61. [PMID: 16511867 DOI: 10.1002/jnr.20818] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cerebrolysin is a peptide mixture with neurotrophic effects that might reduce the neurodegenerative pathology in Alzheimer's disease (AD). We have previously shown in an amyloid protein precursor (APP) transgenic (tg) mouse model of AD-like neuropathology that Cerebrolysin ameliorates behavioral deficits, is neuroprotective, and decreases amyloid burden; however, the mechanisms involved are not completely clear. Cerebrolysin might reduce amyloid deposition by regulating amyloid-beta (Abeta) degradation or by modulating APP expression, maturation, or processing. To investigate these possibilities, APP tg mice were treated for 6 months with Cerebrolysin and analyzed in the water maze, followed by RNA, immunoblot, and confocal microscopy analysis of full-length (FL) APP and its fragments, beta-secretase (BACE1), and Abeta-degrading enzymes [neprilysin (Nep) and insulin-degrading enzyme (IDE)]. Consistent with previous studies, Cerebrolysin ameliorated the performance deficits in the spatial learning portion of the water maze and reduced the synaptic pathology and amyloid burden in the brains of APP tg mice. These effects were associated with reduced levels of FL APP and APP C-terminal fragments, but levels of BACE1, Notch1, Nep, and IDE were unchanged. In contrast, levels of active cyclin-dependent kinase-5 (CDK5) and glycogen synthase kinase-3beta [GSK-3beta; but not stress-activated protein kinase-1 (SAPK1)], kinases that phosphorylate APP, were reduced. Furthermore, Cerebrolysin reduced the levels of phosphorylated APP and the accumulation of APP in the neuritic processes. Taken together, these results suggest that Cerebrolysin might reduce AD-like pathology in the APP tg mice by regulating APP maturation and transport to sites where Abeta protein is generated. This study clarifies the mechanisms through which Cerebrolysin might reduce Abeta production and deposition in AD and further supports the importance of this compound in the potential treatment of early AD.
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Affiliation(s)
- Edward Rockenstein
- Department of Neurosciences, University of California San Diego, School of Medicine, La Jolla, California 92093-0624, USA
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Reznichenko L, Amit T, Zheng H, Avramovich-Tirosh Y, Youdim MBH, Weinreb O, Mandel S. Reduction of iron-regulated amyloid precursor protein and beta-amyloid peptide by (-)-epigallocatechin-3-gallate in cell cultures: implications for iron chelation in Alzheimer's disease. J Neurochem 2006; 97:527-36. [PMID: 16539659 DOI: 10.1111/j.1471-4159.2006.03770.x] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Brain iron dysregulation and its association with amyloid precursor protein (APP) plaque formation are implicated in Alzheimer's disease (AD) pathology and so iron chelation could be considered a rational therapeutic strategy for AD. Here we analyzed the effect of the main polyphenol constituent of green tea, (-)-epigallocatechin-3-gallate (EGCG), which possesses metal-chelating and radical-scavenging properties, on the regulation of the iron metabolism-related proteins APP and transferrin receptor (TfR). EGCG exhibited potent iron-chelating activity comparable to that of the prototype iron chelator desferrioxamine, and dose dependently (1-10 microm) increased TfR protein and mRNA levels in human SH-SY5Y neuroblastoma cells. Both the immature and full-length cellular holo-APP were significantly reduced by EGCG, as shown by two-dimensional gel electrophoresis, without altering APP mRNA levels, suggesting a post-transcriptional action. Indeed, EGCG suppressed the translation of a luciferase reporter gene fused to the APP mRNA 5'-untranslated region, encompassing the APP iron-responsive element. The finding that Fe(2)SO(4) reversed the action of EGCG on APP and TfR proteins reinforces the likelihood that these effects are mediated through modulation of the intracellular iron pool. Furthermore, EGCG reduced toxic beta-amyloid peptide generation in Chinese hamster ovary cells overexpressing the APP 'Swedish' mutation. Thus, the natural non-toxic brain-permeable EGCG may provide a potential therapeutic approach for AD and other iron-associated disorders.
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Affiliation(s)
- L Reznichenko
- Eve Topf and US National Parkinson Foundation Centers for Neurodegenerative diseases and Department of Pharmacology, Faculty of Medicine, Technion, Haifa, Israel
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Alpár A, Ueberham U, Brückner MK, Arendt T, Gärtner U. The expression of wild-type human amyloid precursor protein affects the dendritic phenotype of neocortical pyramidal neurons in transgenic mice. Int J Dev Neurosci 2005; 24:133-40. [PMID: 16384682 DOI: 10.1016/j.ijdevneu.2005.11.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Accepted: 11/10/2005] [Indexed: 11/27/2022] Open
Abstract
The current study addresses the morphoregulatory effects of human amyloid precursor protein expression on neocortical pyramidal cells in vivo. For this purpose, a transgenic mouse line was used that expresses wild-type human amyloid precursor protein (APP) at levels similar to endogenous mouse APP. This strain does not develop Alzheimer's disease-related pathology which allowed to study effects of APP or APP cleavage products but excluded the influence of amyloid deposits. Commissural projecting pyramidal neurons of layers II/III within the primary somatosensory cortex were retrogradely labelled by injection of biotinylated dextran amine into the corpus callosum. In transgenic mice, computer-aided morphometric analysis revealed an increase in the surface area of proximal and intermediate basal dendritic segments resulting from an enlarged diameter. On the other hand, the length of the same segments was reduced. Both basal and apical dendrites were characterized by a higher dendritic density within the proximal and intermediate fields. Although the total spatial extension of basal and apical dendrites remained unchanged, a moderate withdrawal of arbors is suggested. The results implicate a physiological function for APP in regulatory mechanisms of neuronal morphogenesis.
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Affiliation(s)
- Alán Alpár
- Department of Anatomy, Histology and Embryology, Semmelweis University Medical School, Tuzoltó u. 58, H-1450 Budapest, Hungary
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Bar-Am O, Weinreb O, Amit T, Youdim MBH. Regulation of Bcl-2 family proteins, neurotrophic factors, and APP processing in the neurorescue activity of propargylamine. FASEB J 2005; 19:1899-901. [PMID: 16148027 DOI: 10.1096/fj.05-3794fje] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The anti-Parkinson drug, rasagiline (N-propargyl-(1R)-aminoindan) promotes neuronal survival, via neuroprotective activity related to its propargyl moiety (propargylamine). We have investigated the neurorescue effects of propargylamine, in a progressive neuronal death model, induced by long-term serum deprivation in human SH-SY5Y neuroblastoma cells. Propargylamine (0.1-10 microM) dose-dependently reduced the levels of the early apoptosis-associated phosphorylated protein, H2A-X (ser 139), as well as decreased the cleavage of caspase-3 and its substrate poly-ADP ribose polymerase (PARP). In addition, the compound markedly reversed the apoptotic effects induced by long-term serum withdrawal, including down-regulation of the antiapoptotic protein, Bcl-2, as well as up-regulation of the proapoptotic proteins, Bax, Bad, and Bim. Real-time RT-PCR demonstrated that propargylamine elevated gene expression levels of Bcl-2, and the neurotrophic factors glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) and reduced Bax gene expression. Serum deprivation increased mRNA and protein levels of holo-amyloid precursor protein (APP), which was markedly decreased by propargylamine. This was accompanied by inducing the release of the nonamyloidogenic alpha-secretase form of soluble APP (sAPPalpha) into the medium. Similar effects on cell survival and APP regulation/processing were demonstrated for rasagiline. These results indicate that both rasagiline and propargylamine possess neurorescue activity, associated with regulation of Bcl-2 family proteins, neurotrophic factors, and APP metabolism.
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Affiliation(s)
- Orit Bar-Am
- Eve Topf and USA National Parkinson Foundation Centers of Excellence for Neurodegenerative Diseases Research, and Department of Pharmacology, Rappaport Family Research Institute, Technion-Faculty of Medicine, Haifa, Israel
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Korolainen MA, Auriola S, Nyman TA, Alafuzoff I, Pirttilä T. Proteomic analysis of glial fibrillary acidic protein in Alzheimer's disease and aging brain. Neurobiol Dis 2005; 20:858-70. [PMID: 15979880 DOI: 10.1016/j.nbd.2005.05.021] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Revised: 05/12/2005] [Accepted: 05/17/2005] [Indexed: 01/04/2023] Open
Abstract
Chronic inflammation is known to play an important role in the heterogeneous pathogenesis of Alzheimer's disease (AD). Activated astrocytes expressing glial fibrillary acidic protein (GFAP) are closely associated with AD pathology, such as tangles, neuritic plaques and amyloid depositions. Altogether, 46 soluble isoforms of GFAP were separated and most of them quantified by two-dimensional immunoblotting in frontal cortices of AD patients and age-matched controls. A 60% increase in the amount of more acidic isoforms of GFAP was observed in AD and these isoforms were both phosphorylated and N-glycosylated, while more basic isoforms were O-glycosylated and exhibited no quantitative differences between post-mortem AD and control brains. These data highlight the importance of exploring isoform-specific levels of proteins in pathophysiological conditions since modifications of proteins determine their activity state, localization, turnover and interaction with other molecules. Mechanisms, structures and functional consequences of modification of GFAP isoforms remain to be clarified.
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Affiliation(s)
- Minna A Korolainen
- Department of Neuroscience and Neurology, University of Kuopio, Harjulantie 1D, P.O. Box 1627, FIN-70211 Kuopio, Finland.
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