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Sarkar D, Bhunia A. Delineating the Role of GxxxG Motif in Amyloidogenesis: A New Perspective in Targeting Amyloid-Beta Mediated AD Pathogenesis. ACS BIO & MED CHEM AU 2024; 4:4-19. [PMID: 38404748 PMCID: PMC10885112 DOI: 10.1021/acsbiomedchemau.3c00055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/18/2023] [Accepted: 10/18/2023] [Indexed: 02/27/2024]
Abstract
The pursuit of a novel structural motif that can shed light on the key functional attributes is a primary focus in the study of protein folding disorders. Decades of research on Alzheimer's disease (AD) have centered on the Amyloid β (Aβ) pathway, highlighting its significance in understanding the disorder. The diversity in the Aβ pathway and the possible silent tracks which are yet to discover, makes it exceedingly intimidating to the interdisciplinary scientific community. Over the course of AD research, Aβ has consistently been at the forefront of scientific inquiry and discussion. In this review, we epitomize the role of a potential structural motif (GxxxG motif) that may provide a new horizon to the Aβ conflict. We emphasize on how comprehensive understanding of this motif from a structure-function perspective may pave the way for designing novel therapeutics intervention in AD and related diseases.
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Affiliation(s)
- Dibakar Sarkar
- Department of Chemical Sciences, Bose Institute, Unified Academic Campus, Sector V, Salt Lake EN
80, Kolkata 700 091, India
| | - Anirban Bhunia
- Department of Chemical Sciences, Bose Institute, Unified Academic Campus, Sector V, Salt Lake EN
80, Kolkata 700 091, India
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2
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Kaur A, Goyal B. Identification of new pentapeptides as potential inhibitors of amyloid-β 42 aggregation using virtual screening and molecular dynamics simulations. J Mol Graph Model 2023; 124:108558. [PMID: 37390790 DOI: 10.1016/j.jmgm.2023.108558] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 07/02/2023]
Abstract
Alzheimer's disease (AD) is a multifactorial neurodegenerative disease mainly characterized by extracellular accumulation of amyloid-β (Aβ) peptide. Previous studies reported pentapeptide RIIGL as an effective inhibitor of Aβ aggregation and neurotoxicity induced by Aβ aggregates. In this work, a library of 912 pentapeptides based on RIIGL has been designed and assessed for their efficacy to inhibit Aβ42 aggregation using computational techniques. The top hit pentapeptides revealed by molecular docking were further assessed for their binding affinity with Aβ42 monomer using MM-PBSA (molecular mechanics Poisson-Boltzmann surface area) method. The MM-PBSA analysis identified RLAPV, RVVPI, and RIAPA, which bind to Aβ42 monomer with a higher binding affinity -55.80, -46.32, and -44.26 kcal/mol, respectively, as compared to RIIGL (ΔGbinding = -41.29 kcal/mol). The residue-wise binding free energy predicted hydrophobic contacts between Aβ42 monomer and pentapeptides. The secondary structure analysis of the conformational ensembles generated by molecular dynamics (MD) depicted remarkably enhanced sampling of helical and no β-sheet conformations in Aβ42 monomer on the incorporation of RVVPI and RIAPA. Notably, RVVPI and RIAPA destabilized the D23-K28 salt bridge in Aβ42 monomer, which plays a crucial role in Aβ42 oligomer stability and fibril formation. The MD simulations highlighted that the incorporation of proline and arginine in pentapeptides contributed to their strong binding with Aβ42 monomer. Furthermore, RVVPI and RIAPA prevented conformational conversion of Aβ42 monomer to aggregation-prone structures, which, in turn, resulted in a lower aggregation tendency of Aβ42 monomer.
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Affiliation(s)
- Apneet Kaur
- School of Chemistry & Biochemistry, Thapar Institute of Engineering & Technology, Patiala, 147004, Punjab, India
| | - Bhupesh Goyal
- School of Chemistry & Biochemistry, Thapar Institute of Engineering & Technology, Patiala, 147004, Punjab, India.
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3
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Wang C, Shao S, Li N, Zhang Z, Zhang H, Liu B. Advances in Alzheimer's Disease-Associated Aβ Therapy Based on Peptide. Int J Mol Sci 2023; 24:13110. [PMID: 37685916 PMCID: PMC10487952 DOI: 10.3390/ijms241713110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/11/2023] [Accepted: 08/19/2023] [Indexed: 09/10/2023] Open
Abstract
Alzheimer's disease (AD) urgently needs innovative treatments due to the increasing aging population and lack of effective drugs and therapies. The amyloid fibrosis of AD-associated β-amyloid (Aβ) that could induce a series of cascades, such as oxidative stress and inflammation, is a critical factor in the progression of AD. Recently, peptide-based therapies for AD are expected to be great potential strategies for the high specificity to the targets, low toxicity, fast blood clearance, rapid cell and tissue permeability, and superior biochemical characteristics. Specifically, various chiral amino acids or peptide-modified interfaces draw much attention as effective manners to inhibit Aβ fibrillation. On the other hand, peptide-based inhibitors could be obtained through affinity screening such as phage display or by rational design based on the core sequence of Aβ fibrosis or by computer aided drug design based on the structure of Aβ. These peptide-based therapies can inhibit Aβ fibrillation and reduce cytotoxicity induced by Aβ aggregation and some have been shown to relieve cognition in AD model mice and reduce Aβ plaques in mice brains. This review summarizes the design method and characteristics of peptide inhibitors and their effect on the amyloid fibrosis of Aβ. We further describe some analysis methods for evaluating the inhibitory effect and point out the challenges in these areas, and possible directions for the design of AD drugs based on peptides, which lay the foundation for the development of new effective drugs in the future.
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Affiliation(s)
- Cunli Wang
- School of Biomedical Engineering, Faculty of Medicine, Dalian University of Technology, Lingshui Road, Dalian 116024, China; (C.W.); (S.S.); (N.L.); (Z.Z.); (H.Z.)
| | - Shuai Shao
- School of Biomedical Engineering, Faculty of Medicine, Dalian University of Technology, Lingshui Road, Dalian 116024, China; (C.W.); (S.S.); (N.L.); (Z.Z.); (H.Z.)
- Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
| | - Na Li
- School of Biomedical Engineering, Faculty of Medicine, Dalian University of Technology, Lingshui Road, Dalian 116024, China; (C.W.); (S.S.); (N.L.); (Z.Z.); (H.Z.)
- Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
| | - Zhengyao Zhang
- School of Biomedical Engineering, Faculty of Medicine, Dalian University of Technology, Lingshui Road, Dalian 116024, China; (C.W.); (S.S.); (N.L.); (Z.Z.); (H.Z.)
- School of Life and Pharmaceutical Sciences, Dalian University of Technology, Panjin 124221, China
| | - Hangyu Zhang
- School of Biomedical Engineering, Faculty of Medicine, Dalian University of Technology, Lingshui Road, Dalian 116024, China; (C.W.); (S.S.); (N.L.); (Z.Z.); (H.Z.)
- Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
| | - Bo Liu
- School of Biomedical Engineering, Faculty of Medicine, Dalian University of Technology, Lingshui Road, Dalian 116024, China; (C.W.); (S.S.); (N.L.); (Z.Z.); (H.Z.)
- Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
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Yuan N, Ye L, Sun Y, Wu H, Xiao Z, Fu W, Chen Z, Pei Y, Min Y, Wang D. Molecular Integrative Analysis of the Inhibitory Effects of Dipeptides on Amyloid β Peptide 1-42 Polymerization. Int J Mol Sci 2023; 24:ijms24087673. [PMID: 37108834 PMCID: PMC10141046 DOI: 10.3390/ijms24087673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 04/02/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
The major pathological feature of Alzheimer's disease (AD) is the aggregation of amyloid β peptide (Aβ) in the brain. Inhibition of Aβ42 aggregation may prevent the advancement of AD. This study employed molecular dynamics, molecular docking, electron microscopy, circular dichroism, staining of aggregated Aβ with ThT, cell viability, and flow cytometry for the detection of reactive oxygen species (ROS) and apoptosis. Aβ42 polymerizes into fibrils due to hydrophobic interactions to minimize free energy, adopting a β-strand structure and forming three hydrophobic areas. Eight dipeptides were screened by molecular docking from a structural database of 20 L-α-amino acids, and the docking was validated by molecular dynamics (MD) analysis of binding stability and interaction potential energy. Among the dipeptides, arginine dipeptide (RR) inhibited Aβ42 aggregation the most. The ThT assay and EM revealed that RR reduced Aβ42 aggregation, whereas the circular dichroism spectroscopy analysis showed a 62.8% decrease in β-sheet conformation and a 39.3% increase in random coiling of Aβ42 in the presence of RR. RR also significantly reduced the toxicity of Aβ42 secreted by SH-SY5Y cells, including cell death, ROS production, and apoptosis. The formation of three hydrophobic regions and polymerization of Aβ42 reduced the Gibbs free energy, and RR was the most effective dipeptide at interfering with polymerization.
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Affiliation(s)
- Nan Yuan
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Lianmeng Ye
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Yan Sun
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Hao Wu
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Zhengpan Xiao
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Wanmeng Fu
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Zuqian Chen
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou 570228, China
| | - Yechun Pei
- One Health Cooperative Innovation Center, Hainan University, Haikou 570228, China
- Department of Biosciences, School of Life Sciences, Hainan University, Haikou 570228, China
| | - Yi Min
- Department of Biosciences, School of Life Sciences, Hainan University, Haikou 570228, China
| | - Dayong Wang
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou 570228, China
- One Health Cooperative Innovation Center, Hainan University, Haikou 570228, China
- Key Laboratory of Tropical Biological Resources of the Ministry of China, Hainan University, Haikou 570228, China
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The interacting rotifer-biopolymers are anti- and disaggregating agents for human-type beta-amyloid in vitro. Int J Biol Macromol 2022; 201:262-269. [PMID: 34999044 DOI: 10.1016/j.ijbiomac.2021.12.184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 12/17/2021] [Accepted: 12/29/2021] [Indexed: 01/06/2023]
Abstract
Neurodegeneration-related human-type beta-amyloid 1-42 aggregates (H-Aβ) are one of the biochemical markers and executive molecules in Alzheimer's disease. The exogenic rotifer-specific biopolymer, namely Rotimer, has a protective effect against H-Aβ toxicity on Euchlanis dilatata and Lecane bulla monogonant rotifers. Due to the external particle-dependent secreting activity of these animals, this natural exudate exists in a bound form on the surface of epoxy-metal beads, named as Rotimer Inductor Conglomerate (RIC). In this current work the experiential in vitro molecular interactions between Rotimer and Aβs are presented. The RIC form was uniformly used against H-Aβ aggregation processes in stagogram- and fluorescent-based experiments. These well-known cell-toxic aggregates stably and quickly (only taking a few minutes) bind to RIC. The epoxy beads (as carriers) alone or the scrambled version of H-Aβ (with random amino acid sequence) were the ineffective and inactive negative controls of this experimental system. The RIC has significant interacting, anti-aggregating and disaggregating effects on H-Aβ. To detect these experiments, Bis-ANS and Thioflavin T were applied during amyloid binding, two aggregation-specific functional fluorescent dyes with different molecular characteristics. This newly described empirical interaction of Rotimer with H-Aβ is a potential starting point and source of innovation concerning targeted human- and pharmaceutical applications.
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6
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Breaker peptides against amyloid-β aggregation: a potential therapeutic strategy for Alzheimer's disease. Future Med Chem 2021; 13:1767-1794. [PMID: 34498978 DOI: 10.4155/fmc-2021-0184] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder, for which blocking the early steps of extracellular misfolded amyloid-β (Aβ) aggregation is a promising therapeutic approach. However, the pathological features of AD progression include the accumulation of intracellular tau protein, membrane-catalyzed cell death and the abnormal deposition of Aβ. Here, we focus on anti-amyloid breaker peptides derived from the Aβ sequence and non-Aβ-based peptides containing both natural and modified amino acids. Critical aspects of the breaker peptides include N-methylation, conformational restriction through cyclization, incorporation of unnatural amino acid, fluorinated molecules, polymeric nanoparticles and PEGylation. This review confers a general idea of such breaker peptides with in vitro and in vivo studies, which may advance our understanding of AD pathology and develop an effective treatment strategy against AD.
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7
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Li X, Xie B, Sun Y. Basified Human Lysozyme: A Potent Inhibitor against Amyloid β-Protein Fibrillogenesis. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:15569-15577. [PMID: 30407837 DOI: 10.1021/acs.langmuir.8b03278] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The aggregation of amyloid β-proteins (Aβ) has been recognized as a key process in the pathogenesis of Alzheimer's disease (AD), so inhibiting Aβ aggregation is an important strategy to prevent the onset and treatment of AD. Our recent work indicated that decreasing the positive charges (or introducing negative charges) on human lysozyme (hLys) was unfavorable in keeping the inhibiting capability of hLys on Aβ aggregation. Therefore, we have herein proposed to basify hLys by conversion of the carboxyl groups into amino groups by modification with ethylene diamine. Basified hLys (Lys-B) preparations of three modification degrees (MDs), denoted as hLys-B1 (MD, 1.5), hLys-B2 (MD, 3.3), and hLys-B3 (MD, 4.4), were synthesized for modulating Aβ fibrillogenesis. The hLys-B preparations kept the stability and biocompatibility as native hLys did, whereas the inhibitory potency of hLys-B on Aβ fibrillogenesis increased with increasing MD. Cytotoxicity analysis showed that cell viability with 2.5 μM hLys-B3 increased from 62.5% (with 25 μM Aβ only) to 76.1%, similar to the case with 12.5 μM hLys (75.5%); cell viability with 6.25 μM hLys-B3 increased to 82.0%, similar to the case with 25 μM hLys (80.9%). The results indicate about four- to fivefold increase in the inhibition efficiency of hLys by the amino modification. Mechanistic analysis suggests that such a superior inhibitory capability of hLys-B was attributed to its more widely distributed positive charges, which promoted broad electrostatic interactions between Aβ and hLys-B. Thus, hLys-B suppressed the conformational transition of Aβ to β-sheet structures at low concentrations (e.g., 2.5 μM hLys-B3), leading to changes in the aggregation pathway and the formation of Aβ species with less cytotoxicity. The findings provided new insights into the development of more potent protein-based inhibitors against Aβ fibrillogenesis.
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Affiliation(s)
- Xi Li
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300354 , China
| | - Baolong Xie
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300354 , China
- Institute of Tianjin Seawater Desalination and Multipurpose Utilization, State Oceanic Administration (SOA) , Tianjin 300192 , China
| | - Yan Sun
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology , Tianjin University , Tianjin 300354 , China
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8
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Zhang H, Dong X, Liu F, Zheng J, Sun Y. Ac-LVFFARK-NH 2 conjugation to β-cyclodextrin exhibits significantly enhanced performance on inhibiting amyloid β-protein fibrillogenesis and cytotoxicity. Biophys Chem 2018; 235:40-47. [DOI: 10.1016/j.bpc.2018.02.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 01/12/2018] [Accepted: 02/04/2018] [Indexed: 11/16/2022]
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9
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Goyal D, Shuaib S, Mann S, Goyal B. Rationally Designed Peptides and Peptidomimetics as Inhibitors of Amyloid-β (Aβ) Aggregation: Potential Therapeutics of Alzheimer's Disease. ACS COMBINATORIAL SCIENCE 2017; 19:55-80. [PMID: 28045249 DOI: 10.1021/acscombsci.6b00116] [Citation(s) in RCA: 150] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease with no clinically accepted treatment to cure or halt its progression. The worldwide effort to develop peptide-based inhibitors of amyloid-β (Aβ) aggregation can be considered an unplanned combinatorial experiment. An understanding of what has been done and achieved may advance our understanding of AD pathology and the discovery of effective therapeutic agents. We review here the history of such peptide-based inhibitors, including those based on the Aβ sequence and those not derived from that sequence, containing both natural and unnatural amino acid building blocks. Peptide-based aggregation inhibitors hold significant promise for future AD therapy owing to their high selectivity, effectiveness, low toxicity, good tolerance, low accumulation in tissues, high chemical and biological diversity, possibility of rational design, and highly developed methods for analyzing their mode of action, proteolytic stability (modified peptides), and blood-brain barrier (BBB) permeability.
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Affiliation(s)
- Deepti Goyal
- Department of Chemistry,
School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140406, Punjab, India
| | - Suniba Shuaib
- Department of Chemistry,
School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140406, Punjab, India
| | - Sukhmani Mann
- Department of Chemistry,
School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140406, Punjab, India
| | - Bhupesh Goyal
- Department of Chemistry,
School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140406, Punjab, India
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10
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Li H, Rahimi F, Bitan G. Modulation of Amyloid β-Protein (Aβ) Assembly by Homologous C-Terminal Fragments as a Strategy for Inhibiting Aβ Toxicity. ACS Chem Neurosci 2016; 7:845-56. [PMID: 27322435 DOI: 10.1021/acschemneuro.6b00154] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Self-assembly of amyloid β-protein (Aβ) into neurotoxic oligomers and fibrillar aggregates is a key process thought to be the proximal event leading to development of Alzheimer's disease (AD). Therefore, numerous attempts have been made to develop reagents that disrupt this process and prevent the formation of the toxic oligomers and aggregates. An attractive strategy for developing such reagents is to use peptides derived from Aβ based on the assumption that such peptides would bind to full-length Aβ, interfere with binding of additional full-length molecules, and thereby prevent formation of the toxic species. Guided by this rationale, most of the studies in the last two decades have focused on preventing formation of the core cross-β structure of Aβ amyloid fibrils using β-sheet-breaker peptides derived from the central hydrophobic cluster of Aβ. Though this approach is effective in inhibiting fibril formation, it is generally inefficient in preventing Aβ oligomerization. An alternative approach is to use peptides derived from the C-terminus of Aβ, which mediates both oligomerization and fibrillogenesis. This approach has been explored by several groups, including our own, and led to the discovery of several lead peptides with moderate to high inhibitory activity. Interestingly, the mechanisms of these inhibitory effects have been found to be diverse, and only in a small percentage of cases involved interference with β-sheet formation. Here, we review the strategy of using C-terminal fragments of Aβ as modulators of Aβ assembly and discuss the relevant challenges, therapeutic potential, and mechanisms of action of such fragments.
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Affiliation(s)
- Huiyuan Li
- West Virginia University, Morgantown, West Virginia 26506, United States
| | - Farid Rahimi
- Biomedical
Science and Biochemistry, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Gal Bitan
- Department
of Neurology, David Geffen School of Medicine, Brain Research Institute,
and Molecular Biology Institute, University of California at Los Angeles, Neuroscience Research Building 1, Room 451 635 Charles E. Young Drive
South, Los Angeles, California 90095-7334, United States
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11
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Antimisiaris S, Mourtas S, Markoutsa E, Skouras A, Papadia K. Nanoparticles for Diagnosis and/or Treatment of Alzheimer's Disease. Adv Healthc Mater 2014. [DOI: 10.1002/9781118774205.ch4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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12
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Acerra N, Kad NM, Mason JM. Combining intracellular selection with protein-fragment complementation to derive Aβ interacting peptides. Protein Eng Des Sel 2013; 26:463-70. [PMID: 23708321 PMCID: PMC3690830 DOI: 10.1093/protein/gzt021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Aggregation of the β-amyloid (Aβ) peptide into toxic oligomers is considered the primary event in the pathogenesis of Alzheimer's disease. Previously generated peptides and mimetics designed to bind to amyloid fibrils have encountered problems in solubility, protease susceptibility and the population of small soluble toxic oligomers. We present a new method that opens the possibility of deriving new amyloid inhibitors. The intracellular protein-fragment complementation assay (PCA) approach uses a semi-rational design approach to generate peptides capable of binding to Aβ. Peptide libraries are based on Aβ regions responsible for instigating amyloidosis, with screening and selection occurring entirely inside Escherichia coli. Successfully selected peptides must therefore bind Aβ and recombine an essential enzyme while permitting bacterial cell survival. No assumptions are made regarding the mechanism of action for selected binders. Biophysical characterisation demonstrates that binding induces a noticeable reduction in amyloid. Therefore, this amyloid-PCA approach may offer a new pathway for the design of effective inhibitors against the formation of amyloid in general.
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Affiliation(s)
- Nicola Acerra
- The School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
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13
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Li H, Zemel R, Lopes DHJ, Monien BH, Bitan G. A two-step strategy for structure-activity relationship studies of N-methylated aβ42 C-terminal fragments as aβ42 toxicity inhibitors. ChemMedChem 2012; 7:515-22. [PMID: 22307963 DOI: 10.1002/cmdc.201100584] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Indexed: 01/10/2023]
Abstract
Neurotoxic Aβ42 oligomers are believed to be the main cause of Alzheimer's disease. Previously, we found that the C-terminal fragments (CTFs), Aβ(30-42) and Aβ(31-42) were the most potent inhibitors of Aβ42 oligomerization and toxicity in a series of Aβ(x-42) peptides (x=28-39). Therefore, we chose these peptides as leads for further development. These CTFs are short (12-13 amino acids) hydrophobic peptides with limited aqueous solubility. Our first attempt to attach hydrophilic groups to the N terminus resulted in toxic peptides. Therefore, we next incorporated N-methyl amino acids, which are known to increase the solubility of such peptides by disrupting the β-sheet formation. Focusing on Aβ(31-42), we used a two-step N-methyl amino acid substitution strategy to study the structural factors controlling inhibition of Aβ42-induced toxicity. First, each residue was substituted by N-Me-alanine (N-Me-A). In the next step, in positions where substitution produced a significant effect, we restored the original side chain. This strategy allowed exploring the role of both side chain structure and N-Me substitution in inhibitory activity. We found that the introduction of an N-Me amino acid was an effective way to increase both the aqueous solubility and the inhibitory activity of Aβ(31-42). In particular, N-Me amino acid substitution at position 9 or 11 increased the inhibitory activity relative to the parent peptide. The data suggest that inhibition of Aβ42 toxicity by short peptides is highly structure-specific, providing a basis for the design of new peptidomimetic inhibitors with improved activity, physicochemical properties, and metabolic stability.
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Affiliation(s)
- Huiyuan Li
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles (UCLA), 635 Charles E. Young Drive S., Los Angeles, CA 90095, USA
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14
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Funke SA, Willbold D. Peptides for therapy and diagnosis of Alzheimer's disease. Curr Pharm Des 2012; 18:755-67. [PMID: 22236121 PMCID: PMC3426787 DOI: 10.2174/138161212799277752] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Accepted: 12/09/2011] [Indexed: 12/21/2022]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder with devastating effects. The greatest risk factor to develop AD is age. Today, only symptomatic therapies are available. Additionally, AD can be diagnosed with certainty only post mortem, whereas the diagnosis "probable AD" can be established earliest when severe clinical symptoms appear. Specific neuropathological changes like neurofibrillary tangles and amyloid plaques define AD. Amyloid plaques are mainly composed of the amyloid-βpeptide (Aβ). Several lines of evidence suggest that the progressive concentration and subsequent aggregation and accumulation of Aβ play a fundamental role in the disease progress. Therefore, substances which bind to Aβ and influence aggregation thereof are of great interest. An enormous number of organic substances for therapeutic purposes are described. This review focuses on peptides developed for diagnosis and therapy of AD and discusses the pre- and disadvantages of peptide drugs.
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Affiliation(s)
| | - Dieter Willbold
- Forschungszentrum Jülich, ICS-6, 52425 Jülich, Germany
- Institut für Physikalische Biologie, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
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15
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Bett CK, Serem WK, Fontenot KR, Hammer RP, Garno JC. Effects of peptides derived from terminal modifications of the aβ central hydrophobic core on aβ fibrillization. ACS Chem Neurosci 2010; 1:661-78. [PMID: 22778807 DOI: 10.1021/cn900019r] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 08/05/2010] [Indexed: 01/06/2023] Open
Abstract
Considerable research effort has focused on the discovery of mitigators that block the toxicity of the β-amyloid peptide (Aβ) by targeting a specific step involved in Aβ fibrillogenesis and subsequent aggregation. Given that aggregation intermediates are hypothesized to be responsible for Aβ toxicity, such compounds could likely prevent or mitigate aggregation, or alternatively cause further association of toxic oligomers into larger nontoxic aggregates. Herein we investigate the effect of modifications of the KLVFF hydrophobic core of Aβ by replacing N- and C-terminal groups with various polar moieties. Several of these terminal modifications were found to disrupt the formation of amyloid fibrils and in some cases induced the disassembly of preformed fibrils. Significantly, mitigators that incorporate MiniPEG polar groups were found to be effective against Aβ(1-40) fibrilligonesis. Previously, we have shown that mitigators incorporating alpha,alpha-disubstituted amino acids (ααAAs) were effective in disrupting fibril formation as well as inducing fibril disassembly. In this work, we further disclose that the number of polar residues (six) and ααAAs (three) in the original mitigator can be reduced without dramatically changing the ability to disrupt Aβ(1-40) fibrillization in vitro.
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Affiliation(s)
- Cyrus K. Bett
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803
| | - Wilson K. Serem
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803
| | - Krystal R. Fontenot
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803
| | - Robert P. Hammer
- New England Peptide LLC, 65 Zub Lane, Gardner, Massachusetts 01440
| | - Jayne C. Garno
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803
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16
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Zhou Y, Jiang C, Zhang Y, Liang Z, Liu W, Wang L, Luo C, Zhong T, Sun Y, Zhao L, Xie X, Jiang H, Zhou N, Liu D, Liu H. Structural Optimization and Biological Evaluation of Substituted Bisphenol A Derivatives as β-Amyloid Peptide Aggregation Inhibitors. J Med Chem 2010; 53:5449-66. [DOI: 10.1021/jm1000584] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Yu Zhou
- State Key Laboratory of Drug Research
| | | | - Yaping Zhang
- Institute of Biochemistry, College of Life Sciences, Zijingang Campus, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | | | - Wenfeng Liu
- State Key Laboratory of Drug Research
- School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, China
| | - Liefeng Wang
- Laboratory of Receptor-Based Bio-Medicine, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Cheng Luo
- State Key Laboratory of Drug Research
| | - Tingting Zhong
- Institute of Biochemistry, College of Life Sciences, Zijingang Campus, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Yi Sun
- Institute of Biochemistry, College of Life Sciences, Zijingang Campus, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Linxiang Zhao
- School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, China
| | - Xin Xie
- State Key Laboratory of Drug Research
| | | | - Naiming Zhou
- Institute of Biochemistry, College of Life Sciences, Zijingang Campus, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | | | - Hong Liu
- State Key Laboratory of Drug Research
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17
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Dasilva KA, Shaw JE, McLaurin J. Amyloid-beta fibrillogenesis: structural insight and therapeutic intervention. Exp Neurol 2009; 223:311-21. [PMID: 19744483 DOI: 10.1016/j.expneurol.2009.08.032] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 08/12/2009] [Accepted: 08/27/2009] [Indexed: 02/02/2023]
Abstract
Structural insight into the conformational changes associated with aggregation and assembly of fibrils has provided a number of targets for therapeutic intervention. Solid-state NMR, hydrogen/deuterium exchange and mutagenesis strategies have been used to probe the secondary and tertiary structure of amyloid fibrils and key intermediates. Rational design of peptide inhibitors directed against key residues important for aggregation and stabilization of fibrils has demonstrated effectiveness at inhibiting fibrillogenesis. Studies on the interaction between Abeta and cell membranes led to the discovery that inositol, the head group of phosphatidylinositol, inhibits fibrillogenesis. As a result, scyllo-inositol is currently in clinical trials for the treatment of AD. Additional small-molecule inhibitors, including polyphenolic compounds such as curcumin, (-)-epigallocatechin gallate (EGCG), and grape seed extract have been shown to attenuate Abeta aggregation through distinct mechanisms, and have shown effectiveness at reducing amyloid levels when administered to transgenic mouse models of AD. Although the results of ongoing clinical trials remain to be seen, these compounds represent the first generation of amyloid-based therapeutics, with the potential to alter the progression of AD and, when used prophylactically, alleviate the deposition of Abeta.
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Affiliation(s)
- Kevin A Dasilva
- Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
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18
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Hamill AC, Lee CT. Photocontrol of β-Amyloid Peptide (1−40) Fibril Growth in the Presence of a Photosurfactant. J Phys Chem B 2009; 113:6164-72. [DOI: 10.1021/jp8080113] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrea C. Hamill
- Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-1211
| | - C. Ted Lee
- Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-1211
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19
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Xiong ZM, Kitagawa K, Nishiuchi Y, Kimura T, Nakamura T, Inagaki C. Acetyl-Ile-Gly-Leu protects neurons from Aβ1–42 induced toxicity in vitro and in V337M human tau-expressing mice. Life Sci 2009; 84:132-8. [DOI: 10.1016/j.lfs.2008.11.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 11/04/2008] [Accepted: 11/12/2008] [Indexed: 11/25/2022]
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20
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Hetényi A, Fülöp L, Martinek TA, Wéber E, Soós K, Penke B. Ligand-Induced Flocculation of Neurotoxic Fibrillar Aβ(1–42) by Noncovalent Crosslinking. Chembiochem 2008; 9:748-57. [DOI: 10.1002/cbic.200700351] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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21
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Hunya Á, Földi I, Szegedi V, Soós K, Zarándi M, Szabó A, Zádori D, Penke B, Datki ZL. Differences between normal and alpha-synuclein overexpressing SH-SY5Y neuroblastoma cells after Aβ(1-42) and NAC treatment. Brain Res Bull 2008; 75:648-54. [DOI: 10.1016/j.brainresbull.2007.10.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Revised: 09/27/2007] [Accepted: 10/22/2007] [Indexed: 12/31/2022]
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22
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Pérez de Vega MJ, Baeza JL, García-López MT, Vila-Perelló M, Jiménez-Castells C, Simón AM, Frechilla D, del Río J, Gutiérrez-Gallego R, Andreu D, González-Muñiz R. Synthesis and biological properties of β-turned Aβ31–35 constrained analogues. Bioorg Med Chem Lett 2008; 18:2078-82. [DOI: 10.1016/j.bmcl.2008.01.092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 01/23/2008] [Accepted: 01/24/2008] [Indexed: 10/22/2022]
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23
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Wang SSS, Wu JW, Yamamoto S, Liu HS. Diseases of protein aggregation and the hunt for potential pharmacological agents. Biotechnol J 2008; 3:165-92. [DOI: 10.1002/biot.200700065] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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24
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25
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Das U, Hariprasad G, Pasha S, Mann A, Ganguli M, Sharma S, Kaur P, Singh TP, Srinivasan A. Interface peptide of Alzheimer's amyloid beta: application in purification. Biochem Biophys Res Commun 2007; 362:538-42. [PMID: 17707778 DOI: 10.1016/j.bbrc.2007.08.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/03/2007] [Indexed: 10/23/2022]
Abstract
Protein precipitation is a process commonly observed during bacterial expression of heterologous proteins. The high concentration of currently used solubilizing agents limits the scope of purification procedures. Protein solubilizers acting at very low concentrations will allow function-based purification protocols. Such applications are possible where sequence dependent protein-protein interactions occur. Oligomerization and higher order structure formation by proteins are examples where the interface peptide sequences are inhibitors of such interactions. In this study, we show that a partial sequence of Alzheimer's amyloid beta (Abeta) peptide can inhibit the aggregation. This enables the purification of protein containing Abeta sequence.
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Affiliation(s)
- Utpal Das
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
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26
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Xiong ZM, Kitagawa K, Nishiuchi Y, Kimura T, Inagaki C. Protective effects of Aβ-derived tripeptide, Aβ32–34, on Aβ1–42-induced phosphatidylinositol 4-kinase inhibition and neurotoxicity. Neurosci Lett 2007; 419:247-52. [PMID: 17499922 DOI: 10.1016/j.neulet.2007.04.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Revised: 04/10/2007] [Accepted: 04/10/2007] [Indexed: 12/20/2022]
Abstract
We previously reported that the neurotoxicity of pathophysiological concentrations of amyloid beta proteins (Abetas, 0.1-10nM) as assessed by the inhibition of type II phosphatidylinositol 4-kinase (PI4KII) activity and the enhancement of glutamate toxicity was blocked by a short fragment of Abeta, Abeta(31-35). Such protective effects of shorter fragments derived from Abeta(31-35) were examined in this study to reach the shortest effective peptide, using recombinant human PI4KII and primary cultured rat hippocampal neurons. Among the peptides tested (Abeta(31-34), Abeta(31-33), Abeta(31-32), Abeta(32-35), Abeta(33-35), Abeta(34-35), Abeta(32-34), Abeta(33-34) and Abeta(32-33)), Abeta(31-34), Abeta(32-35) and Abeta(32-34) blocked both the Abeta(1-42)-induced inhibition of PI4KII activity and enhancement of glutamate toxicity on cell viability. The shortest peptide among them, Abeta(32-34), showed a dose-dependent protective effect with 50% effective concentration near 1nM, while Abeta(34-32), with a reverse amino acid sequence for Abeta(32-34), showed no protective effects. Thus, a tripeptide, Abeta(32-34) i.e. Ile-Gly-Leu, may be available as a lead compound for designing effective Abeta antagonists.
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Affiliation(s)
- Zheng-Mei Xiong
- Department of Pharmacology, Kansai Medical University, Fumizono-cho 10-15, Moriguchi, Osaka 570-8506, Japan
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27
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Martinek TA, Hetényi A, Fülöp L, Mándity IM, Tóth GK, Dékány I, Fülöp F. Secondary structure dependent self-assembly of beta-peptides into nanosized fibrils and membranes. Angew Chem Int Ed Engl 2007; 45:2396-400. [PMID: 16526070 DOI: 10.1002/anie.200504158] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Tamás A Martinek
- Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, 6720 Szeged, Hungary
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28
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Martinek TA, Mándity IM, Fülöp L, Tóth GK, Vass E, Hollósi M, Forró E, Fülöp F. Effects of the Alternating Backbone Configuration on the Secondary Structure and Self-Assembly of β-Peptides. J Am Chem Soc 2006; 128:13539-44. [PMID: 17031967 DOI: 10.1021/ja063890c] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heterochiral homo-oligomers with alternating backbone configurations were constructed by using the different enantiomers of the cis- and trans-2-aminocyclopentanecarboxylic acid (ACPC) monomers. Molecular modeling and the spectroscopic techniques (NMR, ECD, and VCD) unequivocally proved that the alternating heterochiral cis-ACPC sequences form an H10/12 helix, where extra stabilization can be achieved via the cyclic side chains. The ECD and TEM measurements, together with molecular modeling, revealed that the alternating heterochiral trans-ACPC oligomers tend to attain a polar-strand secondary structure in solution, which can self-assemble into nanostructured fibrils. The observations indicate that coverage of all the possible secondary structures (various helix types and strand-mimicking conformations) can be attained with the help of cyclic beta-amino acid diastereomers. A relationship has been established between the backbone chirality pattern and the prevailing secondary structure, which underlines the role of stereochemical control in the beta-peptide secondary structure design and may contribute to future biological applications.
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Affiliation(s)
- Tamás A Martinek
- Institute of Pharmaceutical Chemistry and Department of Medical Chemistry, University of Szeged, H-6701 Szeged, POB 427, Hungary
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29
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Liu D, Xu Y, Feng Y, Liu H, Shen X, Chen K, Ma J, Jiang H. Inhibitor Discovery Targeting the Intermediate Structure of β-Amyloid Peptide on the Conformational Transition Pathway: Implications in the Aggregation Mechanism of β-Amyloid Peptide. Biochemistry 2006; 45:10963-72. [PMID: 16953582 DOI: 10.1021/bi060955f] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Abeta peptides cleaved from the amyloid precursor protein are the main components of senile plaques in Alzheimer's disease. Abeta peptides adopt a conformation mixture of random coil, beta-sheet, and alpha-helix in solution, which makes it difficult to design inhibitors based on the 3D structures of Abeta peptides. By targeting the C-terminal beta-sheet region of an Abeta intermediate structure extracted from molecular dynamics simulations of Abeta conformational transition, a new inhibitor that abolishes Abeta fibrillation was discovered using virtual screening in conjunction with thioflavin T fluorescence assay and atomic force microscopy determination. Circular dichroism spectroscopy demonstrated that the binding of the inhibitor increased the beta-sheet content of Abeta peptides either by stabilizing the C-terminal beta-sheet conformation or by inducing the intermolecular beta-sheet formation. It was proposed that the inhibitor prevented fibrillation by blocking interstrand hydrogen bond formation of the pleated beta-sheet structure commonly found in amyloid fibrils. The study not only provided a strategy for inhibitor design based on the flexible structures of amyloid peptides but also revealed some clues to understanding the molecular events involved in Abeta aggregation.
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Affiliation(s)
- Dongxiang Liu
- Center for Drug Design and Discovery, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
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30
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Martinek TA, Hetényi A, Fülöp L, Mándity IM, Tóth GK, Dékány I, Fülöp F. Secondary Structure Dependent Self-Assembly of β-Peptides into Nanosized Fibrils and Membranes. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200504158] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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31
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Shemer I, Holmgren C, Min R, Fülöp L, Zilberter M, Sousa KM, Farkas T, Härtig W, Penke B, Burnashev N, Tanila H, Zilberter Y, Harkany T. Non-fibrillar β-amyloid abates spike-timing-dependent synaptic potentiation at excitatory synapses in layer 2/3 of the neocortex by targeting postsynaptic AMPA receptors. Eur J Neurosci 2006; 23:2035-47. [PMID: 16630051 DOI: 10.1111/j.1460-9568.2006.04733.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Cognitive decline in Alzheimer's disease (AD) stems from the progressive dysfunction of synaptic connections within cortical neuronal microcircuits. Recently, soluble amyloid beta protein oligomers (Abeta(ol)s) have been identified as critical triggers for early synaptic disorganization. However, it remains unknown whether a deficit of Hebbian-related synaptic plasticity occurs during the early phase of AD. Therefore, we studied whether age-dependent Abeta accumulation affects the induction of spike-timing-dependent synaptic potentiation at excitatory synapses on neocortical layer 2/3 (L2/3) pyramidal cells in the APPswe/PS1dE9 transgenic mouse model of AD. Synaptic potentiation at excitatory synapses onto L2/3 pyramidal cells was significantly reduced at the onset of Abeta pathology and was virtually absent in mice with advanced Abeta burden. A decreased alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)/N-methyl-D-aspartate (NMDA) receptor-mediated current ratio implicated postsynaptic mechanisms underlying Abeta synaptotoxicity. The integral role of Abeta(ol)s in these processes was verified by showing that pretreatment of cortical slices with Abeta((25-35)ol)s disrupted spike-timing-dependent synaptic potentiation at unitary connections between L2/3 pyramidal cells, and reduced the amplitude of miniature excitatory postsynaptic currents therein. A robust decrement of AMPA, but not NMDA, receptor-mediated currents in nucleated patches from L2/3 pyramidal cells confirmed that Abeta(ol)s perturb basal glutamatergic synaptic transmission by affecting postsynaptic AMPA receptors. Inhibition of AMPA receptor desensitization by cyclothiazide significantly increased the amplitude of excitatory postsynaptic potentials evoked by afferent stimulation, and rescued synaptic plasticity even in mice with pronounced Abeta pathology. We propose that soluble Abeta(ol)s trigger the diminution of synaptic plasticity in neocortical pyramidal cell networks during early stages of AD pathogenesis by preferentially targeting postsynaptic AMPA receptors.
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Affiliation(s)
- Isaac Shemer
- Department of Neuroscience, Retzius väg 8:A3-417, Karolinska Institutet, S-17177 Stockholm, Sweden
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Abstract
This review considers the design, synthesis, and mechanistic assessment of peptide-based fibrillogenesis inhibitors, mainly focusing on beta-amyloid, but generalizable to other aggregating proteins and peptides. In spite of revision of the "amyloid hypothesis," the investigation and development of fibrillogenesis inhibitors remain important scientific and therapeutic goals for at least three reasons. First, it is still premature to dismiss fibrils altogether as sources of cytotoxicity. Second, a "fibrillogenesis inhibitor" is typically identified experimentally as such, but these compounds may also bind to intermediates in the fibrillogenesis pathway and have hard-to-predict consequences, including improved clearance of more cytotoxic soluble oligomers. Third, inhibitors are valuable structural probes, as the entire field of enzymology attests. Screening procedures for selection of random inhibitory sequences are briefly considered, but the bulk of the review concentrates on rationally designed fibrillogenesis inhibitors. Among these are internal segments of fibril-forming peptides, amino acid substitutions and side chain modifications of fibrillogenic domains, insertion of prolines into or adjacent to fibrillogenic domains, modification of peptide termini, modification of peptide backbone atoms (including N-methylation), peptide cyclization, use of D-amino acids in fibrillogenic domains, and nonpeptidic beta-sheet mimics. Finally, we consider methods of assaying fibrillogenesis inhibitors, including pitfalls in these assays. We consider binding of inhibitor peptides to their targets, but because this is a specific application of the more general and much larger problem of assessing protein-protein interactions, this topic is covered only briefly. Finally, we consider potential applications of inhibitor peptides to therapeutic strategies.
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Lee KH, Shin BH, Shin KJ, Kim DJ, Yu J. A hybrid molecule that prohibits amyloid fibrils and alleviates neuronal toxicity induced by beta-amyloid (1-42). Biochem Biophys Res Commun 2005; 328:816-23. [PMID: 15707952 DOI: 10.1016/j.bbrc.2005.01.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Indexed: 11/16/2022]
Abstract
Inhibition of oligomeric amyloid beta (Abeta) peptide or fibril formation has emerged as a major therapeutic target for developing new drugs for Alzheimer's disease. We focused on developing inhibitors by synthesizing hybrid molecules of ferulic acid and styryl benzene, which has been known as a fibril binder. Initially, cell-based assay was carried out to evaluate the effective compound. A selected effector, 1, alleviated the Abeta-induced neuronal toxicity in differentiated SH-SY5Y human neuroblastoma cells. The effector could also inhibit Abeta fibril formation, monitored by thioflavin T fluorescence intensity assay and transmitted electron microscopic images. A strong binding affinity of 1 to non-fibrous monomer-like Abeta, which was immobilized to a surface chip, was measured using a surface plasmon resonance technique. The data suggest that the effector shifts the equilibrium of multimeric Abeta, inhibiting the pathogenic oligomer or fibril formation.
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Affiliation(s)
- Kyung Hyun Lee
- Department of Chemistry and Education, Seoul National University, Seoul 151-742, Republic of Korea
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