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Amyloid Beta-Peptide Increases BACE1 Translation through the Phosphorylation of the Eukaryotic Initiation Factor-2 α. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:2739459. [PMID: 33014268 PMCID: PMC7525306 DOI: 10.1155/2020/2739459] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 12/02/2022]
Abstract
Alzheimer's disease (AD) is tightly linked to oxidative stress since amyloid beta-peptide (Aβ) aggregates generate free radicals. Moreover, the aggregation of Aβ is increased by oxidative stress, and the neurotoxicity induced by the oligomers and fibrils is in part mediated by free radicals. Interestingly, it has been reported that oxidative stress can also induce BACE1 transcription and expression. BACE1 is the key enzyme in the cleavage of the amyloid precursor protein to produce Aβ, and the expression of this enzyme has been previously shown to be enhanced in the brains of Alzheimer's patients. Here, we have found that BACE1 expression is increased in the hippocampi from AD patients at both the early (Braak stage II) and late (Braak stage VI) stages of the disease as studied by immunohistochemistry and western blot. To address the role of Aβ and oxidative stress in the regulation of BACE1 expression, we have analyzed the effect of subtoxic concentrations of Aβ oligomers (0.25 μM) and H2O2 (10 mM) on a human neuroblastoma cell line. Firstly, our results show that Aβ oligomers and H2O2 induce an increase of BACE1 mRNA as we studied by qPCR. Regarding BACE1 translation, it is dependent on the phosphorylation of the eukaryotic initiation factor 2α (eIF2α), since BACE1 mRNA bears a 5′UTR that avoids its translation under basal conditions. BACE1 5′UTR contains four upstream initiating codons (uAUGs), and its translation is activated when eIF2α is phosphorylated. Consistently, we have obtained that Aβ oligomers and H2O2 increase the levels of BACE1 and p-eIF2α assayed by western blot and confocal microscopy. Our results suggest that Aβ oligomers increase BACE1 translation by phosphorylating eIF2α in a process that involves oxidative stress and conforms a pathophysiological loop, where the Aβ once aggregated favors its own production continuously by the increase in BACE1 expression as observed in AD patients.
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Picón-Pagès P, Bonet J, García-García J, Garcia-Buendia J, Gutierrez D, Valle J, Gómez-Casuso CE, Sidelkivska V, Alvarez A, Perálvarez-Marín A, Suades A, Fernàndez-Busquets X, Andreu D, Vicente R, Oliva B, Muñoz FJ. Human Albumin Impairs Amyloid β-peptide Fibrillation Through its C-terminus: From docking Modeling to Protection Against Neurotoxicity in Alzheimer's disease. Comput Struct Biotechnol J 2019; 17:963-971. [PMID: 31360335 PMCID: PMC6639691 DOI: 10.1016/j.csbj.2019.06.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 06/03/2019] [Accepted: 06/13/2019] [Indexed: 12/01/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative process characterized by the accumulation of extracellular deposits of amyloid β-peptide (Aβ), which induces neuronal death. Monomeric Aβ is not toxic but tends to aggregate into β-sheets that are neurotoxic. Therefore to prevent or delay AD onset and progression one of the main therapeutic approaches would be to impair Aβ assembly into oligomers and fibrils and to promote disaggregation of the preformed aggregate. Albumin is the most abundant protein in the cerebrospinal fluid and it was reported to bind Aβ impeding its aggregation. In a previous work we identified a 35-residue sequence of clusterin, a well-known protein that binds Aβ, that is highly similar to the C-terminus (CTerm) of albumin. In this work, the docking experiments show that the average binding free energy of the CTerm-Aβ1-42 simulations was significantly lower than that of the clusterin-Aβ1-42 binding, highlighting the possibility that the CTerm retains albumin's binding properties. To validate this observation, we performed in vitro structural analysis of soluble and aggregated 1 μM Aβ1-42 incubated with 5 μM CTerm, equimolar to the albumin concentration in the CSF. Reversed-phase chromatography and electron microscopy analysis demonstrated a reduction of Aβ1-42 aggregates when the CTerm was present. Furthermore, we treated a human neuroblastoma cell line with soluble and aggregated Aβ1-42 incubated with CTerm obtaining a significant protection against Aβ-induced neurotoxicity. These in silico and in vitro data suggest that the albumin CTerm is able to impair Aβ aggregation and to promote disassemble of Aβ aggregates protecting neurons.
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Key Words
- AD, Alzheimer's disease
- APP, amyloid precursor protein
- Albumin
- Alzheimer's disease
- Amyloid
- Aß, Amyloid-ß peptide
- CD, Circular dichroism
- CSF, cerebrospinal fluid
- CTerm, albumin C-terminus
- Docking
- HPLC, high performance liquid chromatography
- LC-MS, Liquid chromatography-mass spectrometry
- MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
- NMR, nuclear magnetic resonance
- PBS, phosphate-buffered saline
- PDB, Protein Data Bank
- PPI, protein-protein interactions
- SDS, sodium dodecyl sulfate
- TEM, transmission electron microscopy
- TFA, trifluoroacetic acid
- UV, ultraviolet
- fAβ1–42, HiLyte Fluor488 labelled human Aβ1–42
- β-Sheet
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Affiliation(s)
- Pol Picón-Pagès
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Jaume Bonet
- Laboratory of Structural Bioinformatics (GRIB), Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Javier García-García
- Laboratory of Structural Bioinformatics (GRIB), Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Joan Garcia-Buendia
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Daniela Gutierrez
- Cell Signaling Laboratory, Centro UC de Envejecimiento y Regeneración (CARE), Department of Cellular and Molecular Biology, Biological Sciences Faculty, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Javier Valle
- Laboratory of Proteomics and Protein Chemistry, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Carmen E.S. Gómez-Casuso
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Valeriya Sidelkivska
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Alejandra Alvarez
- Cell Signaling Laboratory, Centro UC de Envejecimiento y Regeneración (CARE), Department of Cellular and Molecular Biology, Biological Sciences Faculty, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alex Perálvarez-Marín
- Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, Centre d'Estudis en Biofísica, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Albert Suades
- Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, Centre d'Estudis en Biofísica, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Xavier Fernàndez-Busquets
- Nanomalaria Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, ES-08028 Barcelona, Spain
- Barcelona Institute for Global Health (ISGlobal, Hospital Clínic-Universitat de Barcelona), Rosselló 149-153, ES-08036 Barcelona, Spain
| | - David Andreu
- Laboratory of Proteomics and Protein Chemistry, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Rubén Vicente
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Baldomero Oliva
- Laboratory of Structural Bioinformatics (GRIB), Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Francisco J. Muñoz
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
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Valls-Comamala V, Guivernau B, Bonet J, Puig M, Perálvarez-Marín A, Palomer E, Fernàndez-Busquets X, Altafaj X, Tajes M, Puig-Pijoan A, Vicente R, Oliva B, Muñoz FJ. The antigen-binding fragment of human gamma immunoglobulin prevents amyloid β-peptide folding into β-sheet to form oligomers. Oncotarget 2017; 8:41154-41165. [PMID: 28467807 PMCID: PMC5522293 DOI: 10.18632/oncotarget.17074] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/22/2017] [Indexed: 02/05/2023] Open
Abstract
The amyloid beta-peptide (Aβ) plays a leading role in Alzheimer's disease (AD) physiopathology. Even though monomeric forms of Aβ are harmless to cells, Aβ can aggregate into β-sheet oligomers and fibrils, which are both neurotoxic. Therefore, one of the main therapeutic approaches to cure or delay AD onset and progression is targeting Aβ aggregation. In the present study, we show that a pool of human gamma immunoglobulins (IgG) protected cortical neurons from the challenge with Aβ oligomers, as assayed by MTT reduction, caspase-3 activation and cytoskeleton integrity. In addition, we report the inhibitory effect of IgG on Aβ aggregation, as shown by Thioflavin T assay, size exclusion chromatography and atomic force microscopy. Similar results were obtained with Palivizumab, a human anti-sincitial virus antibody. In order to dissect the important domains, we cleaved the pool of human IgG with papain to obtain Fab and Fc fragments. Using these cleaved fragments, we functionally identified Fab as the immunoglobulin fragment inhibiting Aβ aggregation, a result that was further confirmed by an in silico structural model. Interestingly, bioinformatic tools show a highly conserved structure able to bind amyloid in the Fab region. Overall, our data strongly support the inhibitory effect of human IgG on Aβ aggregation and its neuroprotective role.
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Affiliation(s)
- Victòria Valls-Comamala
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Biuse Guivernau
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Jaume Bonet
- Laboratory of Structural Bioinformatics (GRIB), Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Marta Puig
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Alex Perálvarez-Marín
- Unitat de Biofísica, Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Ernest Palomer
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Xavier Fernàndez-Busquets
- Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain
- ISGlobal, Barcelona Centre for International Health Research, Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
| | - Xavier Altafaj
- Bellvitge Biomedical Research Institute (IDIBELL) - Unit of Neuropharmacology and Pain, University of Barcelona, Barcelona, Spain
| | - Marta Tajes
- Heart Diseases Biomedical Research Group, IMIM-Hospital del Mar Medical Research Institute, Barcelona, Spain
| | - Albert Puig-Pijoan
- Servei de Neurologia, Hospital del Mar-IMIM-Parc de Salut Mar, Barcelona, Spain
| | - Rubén Vicente
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Baldomero Oliva
- Laboratory of Structural Bioinformatics (GRIB), Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Francisco J. Muñoz
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Spain
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