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Singh K, Kaur A, Goyal B, Goyal D. Harnessing the Therapeutic Potential of Peptides for Synergistic Treatment of Alzheimer's Disease by Targeting Aβ Aggregation, Metal-Mediated Aβ Aggregation, Cholinesterase, Tau Degradation, and Oxidative Stress. ACS Chem Neurosci 2024; 15:2545-2564. [PMID: 38979773 DOI: 10.1021/acschemneuro.4c00246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024] Open
Abstract
Alzheimer's disease (AD) is a progressive multifaceted neurodegenerative disease and remains a formidable global health challenge. The current medication for AD gives symptomatic relief and, thus, urges us to look for alternative disease-modifying therapies based on a multitarget directed approach. Looking at the remarkable progress made in peptide drug development in the last decade and the benefits associated with peptides, they offer valuable chemotypes [multitarget directed ligands (MTDLs)] as AD therapeutics. This review recapitulates the current developments made in harnessing peptides as MTDLs in combating AD by targeting multiple key pathways involved in the disease's progression. The peptides hold immense potential and represent a convincing avenue in the pursuit of novel AD therapeutics. While hurdles remain, ongoing research offers hope that peptides may eventually provide a multifaceted approach to combat AD.
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Affiliation(s)
- Kamaljot Singh
- Department of Chemistry, Faculty of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib, 140406 Punjab, India
| | - Anupamjeet Kaur
- Department of Chemistry, Faculty of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib, 140406 Punjab, India
| | - Bhupesh Goyal
- Department of Chemistry and Biochemistry, Thapar Institute of Engineering & Technology, Patiala, 147004 Punjab, India
| | - Deepti Goyal
- Department of Chemistry, DAV College, Sector 10, Chandigarh 160011, India
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2
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Kepp KP, Robakis NK, Høilund-Carlsen PF, Sensi SL, Vissel B. The amyloid cascade hypothesis: an updated critical review. Brain 2023; 146:3969-3990. [PMID: 37183523 DOI: 10.1093/brain/awad159] [Citation(s) in RCA: 52] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 04/20/2023] [Accepted: 04/23/2023] [Indexed: 05/16/2023] Open
Abstract
Results from recent clinical trials of antibodies that target amyloid-β (Aβ) for Alzheimer's disease have created excitement and have been heralded as corroboration of the amyloid cascade hypothesis. However, while Aβ may contribute to disease, genetic, clinical, imaging and biochemical data suggest a more complex aetiology. Here we review the history and weaknesses of the amyloid cascade hypothesis in view of the new evidence obtained from clinical trials of anti-amyloid antibodies. These trials indicate that the treatments have either no or uncertain clinical effect on cognition. Despite the importance of amyloid in the definition of Alzheimer's disease, we argue that the data point to Aβ playing a minor aetiological role. We also discuss data suggesting that the concerted activity of many pathogenic factors contribute to Alzheimer's disease and propose that evolving multi-factor disease models will better underpin the search for more effective strategies to treat the disease.
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Affiliation(s)
- Kasper P Kepp
- Section of Biophysical and Biomedicinal chemistry, DTU Chemistry, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Nikolaos K Robakis
- Icahn School of Medicine at Mount Sinai Medical Center, New York, NY 10029, USA
| | - Poul F Høilund-Carlsen
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense C, Denmark
- Department of Clinical Research, University of Southern Denmark, 5000 Odense C, Denmark
| | - Stefano L Sensi
- Center for Advanced Studies and Technology-CAST, and Institute for Advanced Biotechnology (ITAB), University G. d'Annunzio of Chieti-Pescara, Chieti, 66013, Italy
- Department of Neuroscience, Imaging, and Clinical Sciences, University G. d'Annunzio of Chieti-Pescara, Chieti, 66013, Italy
| | - Bryce Vissel
- St Vincent's Hospital Centre for Applied Medical Research, St Vincent's Hospital, Sydney, 2010, Australia
- School of Clinical Medicine, UNSW Medicine and Health, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, Sydney, NSW 2052, Australia
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3
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The Protective A673T Mutation of Amyloid Precursor Protein (APP) in Alzheimer's Disease. Mol Neurobiol 2021; 58:4038-4050. [PMID: 33914267 DOI: 10.1007/s12035-021-02385-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 04/05/2021] [Indexed: 10/21/2022]
Abstract
Alzheimer's disease is a progressive neurodegenerative disorder characterized by extracellular amyloid beta peptides and neurofibrillary tangles consisted of intracellular hyperphosphorylated Tau in the hippocampus and cerebral cortex. Most of the mutations in key genes that code for amyloid precursor protein can lead to significant accumulation of these peptides in the brain and cause Alzheimer's disease. Moreover, some point mutations in amyloid precursor protein can cause familial Alzheimer's disease, such as Swedish mutation (KM670/671NL) and A673V mutation. However, recent studies have found that the A673T mutation in amyloid precursor protein gene can protect against Alzheimer's disease, even if it is located next to the Swedish mutation (KM670/671NL) and at the same site as A673V mutation, which are pathogenic. It makes us curious about the protective A673T mutation. Here, we summarize the most recent insights of A673T mutation, focus on their roles in protective mechanisms against Alzheimer's disease, and discuss their involvement in future treatment.
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4
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Kuang Y, Zhang J, Xiong M, Zeng W, Lin X, Yi X, Luo Y, Yang M, Li F, Huang Q. A Novel Nanosystem Realizing Curcumin Delivery Based on Fe 3O 4@Carbon Dots Nanocomposite for Alzheimer's Disease Therapy. Front Bioeng Biotechnol 2020; 8:614906. [PMID: 33344438 PMCID: PMC7744485 DOI: 10.3389/fbioe.2020.614906] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 10/27/2020] [Indexed: 01/08/2023] Open
Abstract
Alzheimer’s disease (AD) is the most common neurodegenerative disease, which seriously affects human health but lacks effective treatment methods. Amyloid β (Aβ) aggregates are considered a possible target for AD treatment. Evidence is increasingly showing that curcumin (CUR) can partly protect cells from Aβ-mediated neurotoxicity by inhibiting Aβ aggregation. However, the efficiency of targeted cellular uptake and bioavailability of CUR is very low due to its poor stability and water-solubility. In order to better improve the cell uptake efficiency and bioavailability of CUR and reduce the cytotoxicity of high-dose CUR, a novel CUR delivery system for AD therapy has been constructed based on the employment of the Fe3O4@carbon dots nanocomposite (Fe3O4@CDs) as the carrier. CUR-Fe3O4@CDs have a strong affinity toward Aβ and effectively inhibit extracellular Aβ fibrillation. In addition, CUR-Fe3O4@CDs can inhibit the production of reactive oxygen species (ROS) mediated by Aβ fibrils and the corresponding neurotoxicity in PC12 cells. More importantly, it can restore nerve damage and maintained neuronal morphology. These results indicate that the application of CUR-Fe3O4@CDs provides a promising platform for the treatment of AD.
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Affiliation(s)
- Ying Kuang
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Department of Anatomy and Neurobiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Oil-tea in Medical Health Care and Functional Product Development Engineering Research Center in Jiangxi, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
| | - Jingwen Zhang
- Oil-tea in Medical Health Care and Functional Product Development Engineering Research Center in Jiangxi, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
| | - Mogao Xiong
- Oil-tea in Medical Health Care and Functional Product Development Engineering Research Center in Jiangxi, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
| | - Weijia Zeng
- Oil-tea in Medical Health Care and Functional Product Development Engineering Research Center in Jiangxi, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
| | - Xiaofeng Lin
- Oil-tea in Medical Health Care and Functional Product Development Engineering Research Center in Jiangxi, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China.,Department of Chemistry, Shantou University, Shantou, China
| | - Xiaoqing Yi
- Oil-tea in Medical Health Care and Functional Product Development Engineering Research Center in Jiangxi, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
| | - Yan Luo
- Oil-tea in Medical Health Care and Functional Product Development Engineering Research Center in Jiangxi, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
| | - Min Yang
- Oil-tea in Medical Health Care and Functional Product Development Engineering Research Center in Jiangxi, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
| | - Feng Li
- Guangdong Provincial Key Laboratory of Brain Function and Disease, Department of Anatomy and Neurobiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Qitong Huang
- Oil-tea in Medical Health Care and Functional Product Development Engineering Research Center in Jiangxi, Key Laboratory of Biomaterials and Biofabrication in Tissue Engineering of Jiangxi Province, Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou, China
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5
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Ali S, Jenkins B, Cheng J, Lobb B, Wei X, Egan S, Charles TC, McConkey BJ, Austin J, Doxey AC. Slr4, a newly identified S-layer protein from marine Gammaproteobacteria, is a major biofilm matrix component. Mol Microbiol 2020; 114:979-990. [PMID: 32804439 PMCID: PMC7821379 DOI: 10.1111/mmi.14588] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 08/06/2020] [Indexed: 01/03/2023]
Abstract
S‐layers are paracrystalline proteinaceous lattices that surround prokaryotic cells, forming a critical interface between the cells and their extracellular environment. Here, we report the discovery of a novel S‐layer protein present in the Gram‐negative marine organism, Pseudoalteromonas tunicata D2. An uncharacterized protein (EAR28894) was identified as the most abundant protein in planktonic cultures and biofilms. Bioinformatic methods predicted a beta‐helical structure for EAR28894 similar to the Caulobacter S‐layer protein, RsaA, despite sharing less than 20% sequence identity. Transmission electron microscopy revealed that purified EAR28894 protein assembled into paracrystalline sheets with a unique square lattice symmetry and a unit cell spacing of ~9.1 nm. An S‐layer was found surrounding the outer membrane in wild‐type cells and completely removed from cells in an EAR28894 deletion mutant. S‐layer material also appeared to be “shed” from wild‐type cells and was highly abundant in the extracellular matrix where it is associated with outer membrane vesicles and other matrix components. EAR28894 and its homologs form a new family of S‐layer proteins that are widely distributed in Gammaproteobacteria including species of Pseudoalteromonas and Vibrio, and found exclusively in marine metagenomes. We propose the name Slr4 for this novel protein family.
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Affiliation(s)
- Sura Ali
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Benjamin Jenkins
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Jiujun Cheng
- Department of Biology, University of Waterloo, Waterloo, ON, Canada.,Metagenom Bio Life Science Inc., Waterloo, ON, Canada
| | - Briallen Lobb
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Xin Wei
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Suhelen Egan
- Centre for Marine Science and Innovation and School of Biological, Earth and Environmental Sciences, The University of New South Wales Sydney, Sydney, NSW, Australia
| | - Trevor C Charles
- Department of Biology, University of Waterloo, Waterloo, ON, Canada.,Metagenom Bio Life Science Inc., Waterloo, ON, Canada
| | | | - John Austin
- Bureau of Microbial Hazards, Health Products and Food Branch, Health Canada, Ottawa, ON, Canada
| | - Andrew C Doxey
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
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6
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Molecular dynamics simulations of copper binding to amyloid-β Glu22 mutants. Heliyon 2019; 6:e03071. [PMID: 31909253 PMCID: PMC6940626 DOI: 10.1016/j.heliyon.2019.e03071] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 11/25/2019] [Accepted: 12/13/2019] [Indexed: 11/21/2022] Open
Abstract
We report microsecond timescale ligand field molecular dynamics simulations of the copper complexes of three known mutants of the amyloid-β peptide, E22G, E22Q and E22K, alongside the naturally occurring sequence. We find that all three mutants lead to formation of less compact structures than the wild-type: E22Q is the most similar to the native peptide, while E22G and especially E22K are markedly different in size, shape and stability. Turn and coil structures dominate all structures studied but subtle differences in helical and β-sheet distribution are noted, especially in the C-terminal region. The origin of these changes is traced to disruption of key salt bridges: in particular, the Asp23-Lys28 bridge that is prevalent in the wild-type is absent in E22G and E22K, while Lys22 in the latter mutant forms a strong association with Asp23. We surmise that the drastically different pattern of salt bridges in the mutants lead to adoption of a different structural ensemble of the peptide backbone, and speculate that this might affect the ability of the mutant peptides to aggregate in the same manner as known for the wild-type.
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7
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Tang N, Sandahl TD, Ott P, Kepp KP. Computing the Pathogenicity of Wilson's Disease ATP7B Mutations: Implications for Disease Prevalence. J Chem Inf Model 2019; 59:5230-5243. [PMID: 31751128 DOI: 10.1021/acs.jcim.9b00852] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Genetic variations in the gene encoding the copper-transport protein ATP7B are the primary cause of Wilson's disease. Controversially, clinical prevalence seems much smaller than the prevalence estimated by genetic screening tools, causing fear that many people are undiagnosed, although early diagnosis and treatment is essential. To address this issue, we benchmarked 16 state-of-the-art computational disease-prediction methods against established data of missense ATP7B mutations. Our results show that the quality of the methods varies widely. We show the importance of optimizing the threshold of the methods used to distinguish pathogenic from nonpathogenic mutations against data of clinically confirmed pathogenic and nonpathogenic mutations. We find that most methods use thresholds that predict too many ATP7B mutations to be pathogenic. Thus, our findings explain the current controversy on Wilson's disease prevalence because meta-analysis and text search methods include many computational estimates that lead to higher disease prevalence than clinically observed. As proteins and diseases differ widely, a one-size-fits-all threshold cannot distinguish pathogenic and nonpathogenic mutations efficiently, as shown here. We also show that amino acid changes with small evolutionary substitution probability, mainly due to amino acid volume, are more associated with the disease, implying a pathological effect on the conformational state of the protein, which could affect copper transport or adenosine triphosphate recognition and hydrolysis. These findings may be a first step toward a more quantitative genotype-phenotype relationship of Wilson's disease.
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Affiliation(s)
- Ning Tang
- DTU Chemistry , Technical University of Denmark , Kemitorvet 206 , 2800 Kongens Lyngby , Denmark
| | - Thomas D Sandahl
- Department of Hepatology and Gastroenterology , Aarhus University Hospital , 8200 Aarhus , Denmark
| | - Peter Ott
- Department of Hepatology and Gastroenterology , Aarhus University Hospital , 8200 Aarhus , Denmark
| | - Kasper P Kepp
- DTU Chemistry , Technical University of Denmark , Kemitorvet 206 , 2800 Kongens Lyngby , Denmark
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8
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Kepp KP, Squitti R. Copper imbalance in Alzheimer’s disease: Convergence of the chemistry and the clinic. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.06.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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9
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Pallarés I, Ventura S. Advances in the Prediction of Protein Aggregation Propensity. Curr Med Chem 2019; 26:3911-3920. [DOI: 10.2174/0929867324666170705121754] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 04/14/2017] [Accepted: 04/20/2017] [Indexed: 12/29/2022]
Abstract
Background:
Protein aggregation into β-sheet-enriched insoluble assemblies is being
found to be associated with an increasing number of debilitating human pathologies, such as Alzheimer’s
disease or type 2 diabetes, but also with premature aging. Furthermore, protein aggregation
represents a major bottleneck in the production and marketing of proteinbased therapeutics.
Thus, the development of methods to accurately forecast the aggregation propensity of a certain
protein is of much value.
Methods/Results:
A myriad of in vitro and in vivo aggregation studies have shown that the aggregation
propensity of a certain polypeptide sequence is highly dependent on its intrinsic properties
and, in most cases, driven by specific short regions of high aggregation propensity. These observations
have fostered the development of a first generation of algorithms aimed to predict protein
aggregation propensities from the protein sequence. A second generation of programs able to map
protein aggregation on protein structures is emerging. Herein, we review the most representative
online accessible predictive tools, emphasizing their main distinctive features and the range of
applications.
Conclusion:
In this review, we describe representative biocomputational approaches to evaluate
the aggregation properties of protein sequences and structures, while illustrating how they can
become very useful tools to target protein aggregation in biomedicine and biotechnology.
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Affiliation(s)
- Irantzu Pallarés
- Institut de Biotecnologia i Biomedicina, Universitat Autonoma de Barcelona, 08193-Bellaterra (Barcelona), Spain
| | - Salvador Ventura
- Institut de Biotecnologia i Biomedicina, Universitat Autonoma de Barcelona, 08193-Bellaterra (Barcelona), Spain
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10
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Mehra R, Kepp KP. Cell size effects in the molecular dynamics of the intrinsically disordered Aβ peptide. J Chem Phys 2019; 151:085101. [DOI: 10.1063/1.5115085] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- Rukmankesh Mehra
- Technical University of Denmark, DTU Chemistry, Building 206, 2800 Kgs. Lyngby, Denmark
| | - Kasper P. Kepp
- Technical University of Denmark, DTU Chemistry, Building 206, 2800 Kgs. Lyngby, Denmark
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11
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A quantitative model of human neurodegenerative diseases involving protein aggregation. Neurobiol Aging 2019; 80:46-55. [DOI: 10.1016/j.neurobiolaging.2019.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 04/02/2019] [Accepted: 04/02/2019] [Indexed: 12/12/2022]
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12
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Navarro S, Ventura S. Computational re-design of protein structures to improve solubility. Expert Opin Drug Discov 2019; 14:1077-1088. [DOI: 10.1080/17460441.2019.1637413] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Susanna Navarro
- Institut de Biotecnologia i de Biomedicina, Parc de Recerca UAB, Mòdul B, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Salvador Ventura
- Institut de Biotecnologia i de Biomedicina, Parc de Recerca UAB, Mòdul B, Universitat Autònoma de Barcelona, Barcelona, Spain
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13
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Tang N, Kepp KP. Aβ42/Aβ40 Ratios of Presenilin 1 Mutations Correlate with Clinical Onset of Alzheimer’s Disease. J Alzheimers Dis 2018; 66:939-945. [DOI: 10.3233/jad-180829] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Ning Tang
- Technical University of Denmark, DTU Chemistry, Kgs. Lyngby, Denmark
| | - Kasper P. Kepp
- Technical University of Denmark, DTU Chemistry, Kgs. Lyngby, Denmark
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14
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Ribarič S. Peptides as Potential Therapeutics for Alzheimer's Disease. Molecules 2018; 23:E283. [PMID: 29385735 PMCID: PMC6017258 DOI: 10.3390/molecules23020283] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 01/26/2018] [Accepted: 01/28/2018] [Indexed: 12/22/2022] Open
Abstract
Intracellular synthesis, folding, trafficking and degradation of proteins are controlled and integrated by proteostasis. The frequency of protein misfolding disorders in the human population, e.g., in Alzheimer's disease (AD), is increasing due to the aging population. AD treatment options are limited to symptomatic interventions that at best slow-down disease progression. The key biochemical change in AD is the excessive accumulation of per-se non-toxic and soluble amyloid peptides (Aβ(1-37/44), in the intracellular and extracellular space, that alters proteostasis and triggers Aβ modification (e.g., by reactive oxygen species (ROS)) into toxic intermediate, misfolded soluble Aβ peptides, Aβ dimers and Aβ oligomers. The toxic intermediate Aβ products aggregate into progressively less toxic and less soluble protofibrils, fibrils and senile plaques. This review focuses on peptides that inhibit toxic Aβ oligomerization, Aβ aggregation into fibrils, or stabilize Aβ peptides in non-toxic oligomers, and discusses their potential for AD treatment.
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Affiliation(s)
- Samo Ribarič
- Institute of Pathophysiology, Faculty of Medicine, Zaloška 4, SI-1000 Ljubljana, Slovenia.
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15
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16
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Trainor K, Broom A, Meiering EM. Exploring the relationships between protein sequence, structure and solubility. Curr Opin Struct Biol 2017; 42:136-146. [PMID: 28160724 DOI: 10.1016/j.sbi.2017.01.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 01/10/2017] [Accepted: 01/11/2017] [Indexed: 10/20/2022]
Abstract
Aggregation can be thought of as a form of protein folding in which intermolecular associations lead to the formation of large, insoluble assemblies. Various types of aggregates can be differentiated by their internal structures and gross morphologies (e.g., fibrillar or amorphous), and the ability to accurately predict the likelihood of their formation by a given polypeptide is of great practical utility in the fields of biology (including the study of disease), biotechnology, and biomaterials research. Here we review aggregation/solubility prediction methods and selected applications thereof. The development of increasingly sophisticated methods that incorporate knowledge of conformations possibly adopted by aggregating polypeptide monomers and predict the internal structure of aggregates is improving the accuracy of the predictions and continually expanding the range of applications.
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Affiliation(s)
- Kyle Trainor
- Department of Chemistry, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
| | - Aron Broom
- Department of Chemistry, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
| | - Elizabeth M Meiering
- Department of Chemistry, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada.
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17
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Kepp KP. Ten Challenges of the Amyloid Hypothesis of Alzheimer’s Disease. J Alzheimers Dis 2016; 55:447-457. [DOI: 10.3233/jad-160550] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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18
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Flores BN, Dulchavsky ME, Krans A, Sawaya MR, Paulson HL, Todd PK, Barmada SJ, Ivanova MI. Distinct C9orf72-Associated Dipeptide Repeat Structures Correlate with Neuronal Toxicity. PLoS One 2016; 11:e0165084. [PMID: 27776165 PMCID: PMC5077081 DOI: 10.1371/journal.pone.0165084] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 10/05/2016] [Indexed: 12/14/2022] Open
Abstract
Hexanucleotide repeat expansions in C9orf72 are the most common inherited cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The expansions elicit toxicity in part through repeat-associated non-AUG (RAN) translation of the intronic (GGGGCC)n sequence into dipeptide repeat-containing proteins (DPRs). Little is known, however, about the structural characteristics and aggregation propensities of the dipeptide units comprising DPRs. To address this question, we synthesized dipeptide units corresponding to the three sense-strand RAN translation products, analyzed their structures by circular dichroism, electron microscopy and dye binding assays, and assessed their relative toxicity when applied to primary cortical neurons. Short, glycine-arginine (GR)3 dipeptides formed spherical aggregates and selectively reduced neuronal survival compared to glycine-alanine (GA)3 and glycine-proline (GP)3 dipeptides. Doubling peptide length had little effect on the structure of GR or GP peptides, but (GA)6 peptides formed β-sheet rich aggregates that bound thioflavin T and Congo red yet lacked the typical fibrillar morphology of amyloids. Aging of (GA)6 dipeptides increased their β-sheet content and enhanced their toxicity when applied to neurons. We also observed that the relative toxicity of each tested dipeptide was proportional to peptide internalization. Our results demonstrate that different C9orf72-related dipeptides exhibit distinct structural properties that correlate with their relative toxicity.
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Affiliation(s)
- Brittany N. Flores
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Mark E. Dulchavsky
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Amy Krans
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Michael R. Sawaya
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, California, United States of America
| | - Henry L. Paulson
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States of America
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Peter K. Todd
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States of America
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan, United States of America
- Veterans Affairs Medical Center, Ann Arbor, Michigan, United States of America
| | - Sami J. Barmada
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States of America
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (MII); (SJB)
| | - Magdalena I. Ivanova
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, United States of America
- Biophysics Program, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (MII); (SJB)
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Kepp KP. Alzheimer's disease due to loss of function: A new synthesis of the available data. Prog Neurobiol 2016; 143:36-60. [PMID: 27327400 DOI: 10.1016/j.pneurobio.2016.06.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 06/10/2016] [Accepted: 06/11/2016] [Indexed: 12/11/2022]
Abstract
Alzheimer's Disease (AD) is a highly complex disease involving a broad range of clinical, cellular, and biochemical manifestations that are currently not understood in combination. This has led to many views of AD, e.g. the amyloid, tau, presenilin, oxidative stress, and metal hypotheses. The amyloid hypothesis has dominated the field with its assumption that buildup of pathogenic β-amyloid (Aβ) peptide causes disease. This paradigm has been criticized, yet most data suggest that Aβ plays a key role in the disease. Here, a new loss-of-function hypothesis is synthesized that accounts for the anomalies of the amyloid hypothesis, e.g. the curious pathogenicity of the Aβ42/Aβ40 ratio, the loss of Aβ caused by presenilin mutation, the mixed phenotypes of APP mutations, the poor clinical-biochemical correlations for genetic variant carriers, and the failure of Aβ reducing drugs. The amyloid-loss view accounts for recent findings on the structure and chemical features of Aβ variants and their coupling to human patient data. The lost normal function of APP/Aβ is argued to be metal transport across neuronal membranes, a view with no apparent anomalies and substantially more explanatory power than the gain-of-function amyloid hypothesis. In the loss-of-function scenario, the central event of Aβ aggregation is interpreted as a loss of soluble, functional monomer Aβ rather than toxic overload of oligomers. Accordingly, new research models and treatment strategies should focus on remediation of the functional amyloid balance, rather than strict containment of Aβ, which, for reasons rationalized in this review, has failed clinically.
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Affiliation(s)
- Kasper P Kepp
- Technical University of Denmark, DTU Chemistry, DK-2800 Kongens Lyngby, Denmark.
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Somavarapu AK, Kepp KP. Direct Correlation of Cell Toxicity to Conformational Ensembles of Genetic Aβ Variants. ACS Chem Neurosci 2015; 6:1990-6. [PMID: 26447342 DOI: 10.1021/acschemneuro.5b00238] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We report a systematic analysis of conformational ensembles generated from multiseed molecular dynamics simulations of all 15 known genetic variants of Aβ42. We show that experimentally determined variant toxicities are largely explained by random coil content of the amyloid ensembles (correlation with smaller EC50 values; R(2) = 0.54, p = 0.01), and to some extent the helix character (more helix-character is less toxic, R(2) = 0.32, p = 0.07) and hydrophobic surface (R(2) = 0.37, p = 0.04). Our findings suggest that qualitative structural features of the amyloids, rather than the quantitative levels, are fundamentally related to neurodegeneration. The data provide molecular explanations for the high toxicity of E22 variants and for the protective features of the recently characterized A2T variant. The identified conformational features, for example, the local helix-coil-strand transitions of the C-terminals of the peptides, are of likely interest in the direct targeting of amyloids by rational drug design.
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Affiliation(s)
- Arun Kumar Somavarapu
- DTU Chemistry, Technical University of Denmark, Kemiorvet 206, DK-2800 Kongens Lyngby, Denmark
| | - Kasper P. Kepp
- DTU Chemistry, Technical University of Denmark, Kemiorvet 206, DK-2800 Kongens Lyngby, Denmark
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