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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: 7] [Impact Index Per Article: 2.3] [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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2
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Perlikowska R. Whether short peptides are good candidates for future neuroprotective therapeutics? Peptides 2021; 140:170528. [PMID: 33716091 DOI: 10.1016/j.peptides.2021.170528] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/18/2021] [Accepted: 02/27/2021] [Indexed: 02/07/2023]
Abstract
Neurodegenerative diseases are a broad group of largely debilitating, and ultimately terminal conditions resulting in progressive degeneration of different brain regions. The observed damages are associated with cell death, structural and functional deficits of neurons, or demyelination. The concept of neuroprotection concerns the administration of the agent, which should reverse some of the damage or prevent further adverse changes. A growing body of evidence suggested that among many classes of compounds considered as neuroprotective agents, peptides derived from natural materials or their synthetic analogs are good candidates. They presented a broad spectrum of activities and abilities to act through diverse mechanisms of action. Biologically active peptides have many properties, including antioxidant, antimicrobial, antiinflammatory, and immunomodulatory effects. Peptides with pro-survival and neuroprotective activities, associated with inhibition of oxidative stress, apoptosis, inflammation and are able to improve cell viability or mitochondrial functions, are also promising molecules of particular interest to the pharmaceutical industries. Peptide multiple activities open the way for broad application potential as therapeutic agents or ingredients of health-promoting functional foods. Significantly, synthetic peptides can be remodeled in numerous ways to have desired features, such as increased solubility or biological stability, as well as selectivity towards a specific receptor, and finally better membrane penetration. This review summarized the most common features of major neurodegenerative disorders, their causes, consequences, and reported new neuroprotective drug development approaches. The author focused on the unique perspectives in neuroprotection and provided a concise survey of short peptides proposed as novel therapeutic agents against various neurodegenerative diseases.
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Affiliation(s)
- Renata Perlikowska
- Department of Biomolecular Chemistry, Faculty of Medicine, Medical University of Lodz, 92-215, Lodz, Poland.
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3
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Eslami M, Sadeghi B, Goshadrou F. Chronic ghrelin administration restores hippocampal long-term potentiation and ameliorates memory impairment in rat model of Alzheimer's disease. Hippocampus 2018; 28:724-734. [PMID: 30009391 DOI: 10.1002/hipo.23002] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 06/09/2018] [Accepted: 06/16/2018] [Indexed: 12/24/2022]
Abstract
Alzheimer's disease (AD), as a common age-related dementia, is a progressive manifestation of cognitive decline following synaptic failure resulted majorly by senile plaques composed of deposits of amyloid beta (Aβ). Ghrelin is a multifunctional peptide hormone with receptors present in various brain tissues including hippocampus and has been associated with neuroprotection, neuromodulation, and memory processing. Here, we investigated the neuroprotective and therapeutic effects of intracerebroventricular (icv) ghrelin infusion for 2 weeks on passive avoidance learning (PAL), memory retention, and synaptic plasticity in the hippocampal dentate gyrus (DG) and CA1 of both normal rats and Aβ1-42-induced neurotoxicity in AD model. Male Wistar rats were evaluated for their passive memory performance using a shuttle box while some groups had already received Aβ1-42 and/or chronic ghrelin. Using field potential recording, the induction of short- and long-term potentiation (STP and LTP) was studied in DG granule cells along with the LTP changes in CA1 pyramidal neurons through stimulation of the medial perforant path (mPP) and Schaffer collaterals (SCs), respectively. Our results demonstrated that chronic ghrelin treatment not only improved memory processing and retrieval in normal rats during the PAL task, but also promoted memory retention and alleviated memory loss by amelioration of Aβ1-42-induced synaptic plasticity impairment in AD subjects through augmentation of field excitatory postsynaptic potential (fEPSP) slope that led to LTP restitution in both the mPP-DG and the CA3-CA1 synapses. Meanwhile, STP was not significantly changed, meaning that although ghrelin enhanced postsynaptic excitability in DG, it did not change presynaptic transmitter release significantly. This suggests the involvement of postsynaptic mechanisms in long-term ghrelin-enhanced memory. In conclusion, it can be inferred that chronic ghrelin administration has an auspicious therapeutic value for impaired cognitive performance and memory deficits in AD-like neuropathology.
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Affiliation(s)
- Maryam Eslami
- Department of Physiology, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Bahman Sadeghi
- Department of Physiology, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Department of Biochemistry, Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran
| | - Fatemeh Goshadrou
- Department of Physiology, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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4
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Shabani S, Sarkaki A, Ali Mard S, Ahangarpour A, Khorsandi L, Farbood Y. Central and peripheral administrations of levothyroxine improved memory performance and amplified brain electrical activity in the rat model of Alzheimer's disease. Neuropeptides 2016; 59:111-116. [PMID: 27640349 DOI: 10.1016/j.npep.2016.09.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/09/2016] [Accepted: 09/08/2016] [Indexed: 11/26/2022]
Abstract
Alzheimer's disease (AD) is associated with cognitive impairments and a decline in the spontaneous neuronal discharge. In the current study, we evaluated the effect of subcutaneous (S.C.) and intrahippocampal (I.H.) administrations of levothyroxine (LT-4) on the passive avoidance and spatial memory, as well as electrophysiological activity in an animal model of AD. One hundred-sixty male Wistar rats were divided into two main groups. The S.C. group included two Sham and four AD (vehicle or L-T4 25, 50 & 100μg/kg); and the I.H. had consisted of two Sham and two AD (vehicle or L-T4 10μg/kg) subgroups. To make an animal model of AD, amyloid beta (Aβ) plus ibotenic acid (Ibo) were injected I.H. Rats were treated with L-T4 and/or normal saline for ten days. Passive avoidance and spatial memory were evaluated in shuttle box and Morris water maze, respectively. Neuronal single unit recording was assessed from hippocampal dentate gyrus (DG). Results showed that the mean latency time (s) increased significantly (p<0.001) in AD animals and decreased significantly in both S.C. and I.H. L-T4 injected AD animals, compared with the AD group (p<0.001). The percentage of total time that animals spent in goal quarter and the step through latency decreased significantly in AD rats (p<0.001) and increased significantly in both S.C. and I.H. L-T4 injected AD animals in comparison with the AD group (p<0.01, p<0.001). Data showed that the average number of spikes/bin significantly decreased in the AD group (p<0.001). The S.C. and I.H. L-T4 injections in AD rats significantly increased the spike rate in comparison to the AD group (p<0.001). In conclusion, both S.C. and I.H. injections of L-T4 alleviated memory deficits and spontaneous neuronal activity in Aβ-induced AD rats. Also, I.H. microinjection of L-T4 had more beneficial effects on memory and neuronal electrophysiological activity in comparison to S.C. administration.
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Affiliation(s)
- Sahreh Shabani
- Physiology Research Center, Department of Physiology, Medical School, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Alireza Sarkaki
- Physiology Research Center, Department of Physiology, Medical School, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Seyyed Ali Mard
- Physiology Research Center, Department of Physiology, Medical School, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Akram Ahangarpour
- Physiology Research Center, Department of Physiology, Medical School, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Layasadat Khorsandi
- Cellular and Molecular Research Center, Department of Anatomical Sciences, Medical School, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Yaghoob Farbood
- Physiology Research Center, Department of Physiology, Medical School, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
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5
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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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6
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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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7
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Lo AC, Tesseur I, Scopes DIC, Nerou E, Callaerts-Vegh Z, Vermaercke B, Treherne JM, De Strooper B, D'Hooge R. Dose-dependent improvements in learning and memory deficits in APPPS1-21 transgenic mice treated with the orally active Aβ toxicity inhibitor SEN1500. Neuropharmacology 2013; 75:458-66. [PMID: 24035915 DOI: 10.1016/j.neuropharm.2013.08.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 07/25/2013] [Accepted: 08/28/2013] [Indexed: 01/13/2023]
Abstract
In the Alzheimer's disease (AD) brain, accumulation of Aβ1-42 peptides is suggested to initiate a cascade of pathological events. To date, no treatments are available that can reverse or delay AD-related symptoms in patients. In the current study, we introduce a new Aβ toxicity inhibitor, SEN1500, which in addition to its block effect on Aβ1-42 toxicity in synaptophysin assays, can be administered orally and cross the blood-brain barrier without adverse effects in mice. In a different set of animals, APPPS1-21 mice were fed with three different doses of SEN1500 (1 mg/kg, 5 mg/kg and 20 mg/kg) for a period of 5 months. Cognition was assessed in a variety of behavioral tests (Morris water maze, social recognition, conditioned taste aversion and passive avoidance). Results suggest a positive effect on cognition with 20 mg/kg SEN1500 compared to control APPPS1-21 mice. However, no changes in soluble or insoluble Aβ1-40 and Aβ1-42 were detected in the brains of SEN1500-fed mice. SEN1500 also attenuated the effect of Aβ1-42 on synaptophysin levels in mouse cortical neurons, which indicated that the compound blocked the synaptic toxicity of Aβ1-42. In vitro and in vivo effects presented here suggest that SEN1500 could be an interesting AD therapeutic.
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Affiliation(s)
- Adrian C Lo
- Laboratory of Biological Psychology, University of Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Belgium
| | - Ina Tesseur
- Center for Human Genetics, University of Leuven, Belgium; VIB Center for the Biology of Disease, VIB, Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Belgium
| | - David I C Scopes
- Senexis Limited, Babraham Research Campus, Cambridge, United Kingdom
| | - Edmund Nerou
- Senexis Limited, Babraham Research Campus, Cambridge, United Kingdom
| | - Zsuzsanna Callaerts-Vegh
- Laboratory of Biological Psychology, University of Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Belgium
| | - Ben Vermaercke
- Laboratory of Biological Psychology, University of Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Belgium
| | - J Mark Treherne
- Senexis Limited, Babraham Research Campus, Cambridge, United Kingdom
| | - Bart De Strooper
- Center for Human Genetics, University of Leuven, Belgium; VIB Center for the Biology of Disease, VIB, Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Belgium
| | - Rudi D'Hooge
- Laboratory of Biological Psychology, University of Leuven, Belgium; Leuven Institute for Neuroscience & Disease (LIND), Belgium.
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8
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Sun N, Funke SA, Willbold D. A survey of peptides with effective therapeutic potential in Alzheimer's disease rodent models or in human clinical studies. Mini Rev Med Chem 2012; 12:388-98. [PMID: 22303971 PMCID: PMC3426789 DOI: 10.2174/138955712800493942] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 06/21/2011] [Accepted: 07/07/2011] [Indexed: 11/29/2022]
Abstract
Alzheimer’s disease (AD) is a devastating neurodegenerative disorder and the most common cause of dementia. Today, only palliative therapies are available. The pathological hallmarks of AD are the presence of neurofibrillary tangles and amyloid plaques, mainly composed of the amyloid-β peptide (Aβ), in the brains of the patients. Several lines of evidence suggest that the increased production and/or decreased cleavage of Aβ and subsequent accumulation of Aβ oligomers and aggregates play a fundamental role in the disease progress. Therefore, substances which bind to Aβ and influence aggregation thereof are of great interest. A wide range of Aβ binding peptides were investigated to date for therapeutic purposes. Only very few were shown to be effective in rodent AD models or in clinical studies. Here, we review those peptides and discuss their possible mechanisms of action.
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Affiliation(s)
- N Sun
- ICS-6, Forschungszentrum Jülich, 52425 Jülich, Germany
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9
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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: 85] [Impact Index Per Article: 7.1] [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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10
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Li H, Du Z, Lopes DHJ, Fradinger EA, Wang C, Bitan G. C-terminal tetrapeptides inhibit Aβ42-induced neurotoxicity primarily through specific interaction at the N-terminus of Aβ42. J Med Chem 2011; 54:8451-60. [PMID: 22087474 DOI: 10.1021/jm200982p] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Inhibition of amyloid β-protein (Aβ)-induced toxicity is a promising therapeutic strategy for Alzheimer's disease (AD). Previously, we reported that the C-terminal tetrapeptide Aβ(39-42) is a potent inhibitor of neurotoxicity caused by Aβ42, the form of Aβ most closely associated with AD. Here, initial structure-activity relationship studies identified key structural requirements, including chirality, side-chain structure, and a free N-terminus, which control Aβ(39-42) inhibitory activity. To elucidate the binding site(s) of Aβ(39-42) on Aβ42, we used intrinsic tyrosine (Y) fluorescence and solution-state NMR. The data suggest that Aβ(39-42) binds at several sites, of which the predominant one is located in the N-terminus of Aβ42, in agreement with recent modeling predictions. Thus, despite the small size of Aβ(39-42) and the hydrophobic, aliphatic nature of all four side-chains, the interaction of Aβ(39-42) with Aβ42 is controlled by specific intermolecular contacts requiring a combination of hydrophobic and electrostatic interactions and a particular stereochemistry.
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Affiliation(s)
- Huiyuan Li
- Department of Neurology, David Geffen School of Medicine, Brain Research Institute, University of California, Los Angeles, 635 Charles E. Young Drive South, Los Angeles, California 90095-7334, United States
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11
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Randall AD, Witton J, Booth C, Hynes-Allen A, Brown JT. The functional neurophysiology of the amyloid precursor protein (APP) processing pathway. Neuropharmacology 2010; 59:243-67. [PMID: 20167227 DOI: 10.1016/j.neuropharm.2010.02.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 01/12/2023]
Abstract
Amyloid beta (Abeta) peptides derived from proteolytic cleavage of amyloid precursor protein (APP) are thought to be a pivotal toxic species in the pathogenesis of Alzheimer's disease (AD). Furthermore, evidence has been accumulating that components of APP processing pathway are involved in non-pathological normal function of the CNS. In this review we aim to cover the extensive body of research aimed at understanding how components of this pathway contribute to neurophysiological function of the CNS in health and disease. We briefly outline changes to clinical neurophysiology seen in AD patients before discussing functional changes in mouse models of AD which range from changes to basal synaptic transmission and synaptic plasticity through to abnormal synchronous network activity. We then describe the various neurophysiological actions that are produced by application of exogenous Abeta in various forms, and finally discuss a number or other neurophysiological aspects of the APP pathway, including functional activities of components of secretase complexes other than Abeta production.
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Affiliation(s)
- A D Randall
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol School of Medical Sciences, Bristol, UK.
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12
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Maji SK, Ogorzalek Loo RR, Inayathullah M, Spring SM, Vollers SS, Condron MM, Bitan G, Loo JA, Teplow DB. Amino acid position-specific contributions to amyloid beta-protein oligomerization. J Biol Chem 2009; 284:23580-91. [PMID: 19567875 PMCID: PMC2749133 DOI: 10.1074/jbc.m109.038133] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Indexed: 12/21/2022] Open
Abstract
Understanding the structural and assembly dynamics of the amyloid beta-protein (Abeta) has direct relevance to the development of therapeutic agents for Alzheimer disease. To elucidate these dynamics, we combined scanning amino acid substitution with a method for quantitative determination of the Abeta oligomer frequency distribution, photo-induced cross-linking of unmodified proteins (PICUP), to perform "scanning PICUP." Tyr, a reactive group in PICUP, was substituted at position 1, 10, 20, 30, or 40 (for Abeta40) or 42 (for Abeta42). The effects of these substitutions were probed using circular dichroism spectroscopy, thioflavin T binding, electron microscopy, PICUP, and mass spectrometry. All peptides displayed a random coil --> alpha/beta --> beta transition, but substitution-dependent alterations in assembly kinetics and conformer complexity were observed. Tyr(1)-substituted homologues of Abeta40 and Abeta42 assembled the slowest and yielded unusual patterns of oligomer bands in gel electrophoresis experiments, suggesting oligomer compaction had occurred. Consistent with this suggestion was the observation of relatively narrow [Tyr(1)]Abeta40 fibrils. Substitution of Abeta40 at the C terminus decreased the population conformational complexity and substantially extended the highest order of oligomers observed. This latter effect was observed in both Abeta40 and Abeta42 as the Tyr substitution position number increased. The ability of a single substitution (Tyr(1)) to alter Abeta assembly kinetics and the oligomer frequency distribution suggests that the N terminus is not a benign peptide segment, but rather that Abeta conformational dynamics and assembly are affected significantly by the competition between the N and C termini to form a stable complex with the central hydrophobic cluster.
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Affiliation(s)
| | - Rachel R. Ogorzalek Loo
- Department of Biological Chemistry, David Geffen School of Medicine
- Molecular Biology Institute
| | | | | | | | | | - Gal Bitan
- From the Department of Neurology and
- Molecular Biology Institute
- Brain Research Institute, and
| | - Joseph A. Loo
- Department of Biological Chemistry, David Geffen School of Medicine
- Molecular Biology Institute
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095
| | - David B. Teplow
- From the Department of Neurology and
- Molecular Biology Institute
- Brain Research Institute, and
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13
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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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14
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Szegedi V, Juhász G, Rózsa E, Juhász-Vedres G, Datki Z, Fülöp L, Bozsó Z, Lakatos A, Laczkó I, Farkas T, Kis Z, Tóth G, Soós K, Zarándi M, Budai D, Toldi J, Penke B. Endomorphin‐2, an endogenous tetrapeptide, protects against Aβ1‐42
in vitro
and
in vivo. FASEB J 2006; 20:1191-3. [PMID: 16636106 DOI: 10.1096/fj.05-4891fje] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The underlying cause of Alzheimer's disease (AD) is thought to be the beta-amyloid aggregates formed mainly by Abeta1-42 peptide. Protective pentapeptides [e.g., Leu-Pro-Phe-Phe-Asp (LPFFD)] have been shown to prevent neuronal toxicity of Abeta1-42 by arresting and reversing fibril formation. Here we report that an endogenous tetrapeptide, endomorphin-2 (End-2, amino acid sequence: YPFF), defends against Abeta1-42 induced neuromodulatory effects at the cellular level. Although End-2 does not interfere with the kinetics of Abeta fibrillogenesis according to transmission electron microscopic studies and quasielastic light scattering measurements, it binds to Abeta1-42 during aggregation, as revealed by tritium-labeled End-2 binding assay and circular dichroism measurements. The tetrapeptide attenuates the inhibitory effect on cellular redox activity of Abeta1-42 in a dose-dependent manner, as measured by 3-(4,5-dimethylthiazolyl-2)-2,-5-diphenyltetrazolium bromide (MTT) assay. In vitro and in vivo electrophysiological experiments show that End-2 also protects against the field excitatory postsynaptic potential attenuating and the NMDA-evoked response-enhancing effect of Abeta1-42. Studies using [D-Ala (2), N-Me-Phe (4), Gly (5)-ol]-enkephalin (DAMGO), a mu-opioid receptor agonist, show that the protective effects of the tetrapeptide are not mu-receptor modulated. The endogenous tetrapeptide End-2 may serve as a lead compound for the drug development in the treatment of AD.
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Affiliation(s)
- Viktor Szegedi
- Department of Medical Chemistry, University of Szeged, Dóm Square 8, Szeged 6720, Hungary.
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15
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Szegedi V, Juhász G, Budai D, Penke B. Divergent effects of Abeta1-42 on ionotropic glutamate receptor-mediated responses in CA1 neurons in vivo. Brain Res 2005; 1062:120-6. [PMID: 16248989 DOI: 10.1016/j.brainres.2005.09.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Revised: 09/08/2005] [Accepted: 09/25/2005] [Indexed: 11/28/2022]
Abstract
Aggregated Abeta1-42 is hypothesized to be the central cause of Alzheimer's disease. However, early changes in synaptic activity may be detected in the disease long before a significant cell loss is manifested. Despite the fact that Abeta1-42 interference with long-term potentiation (LTP) and the field excitatory postsynaptic potential (fEPSP) is well documented, the exact mechanism of these events remains to be clarified. Here we studied the effects of iontophoretically applied Abeta1-42 on the neuronal firing evoked in vivo on the CA1 hippocampal neurons of Wistar rats by different agonists of the ionotropic glutamate receptors: N-methyl-d-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and kainic acid (KA). NMDA elicited firing enhanced in all of the measured cells; in contrast, the AMPA-mediated responses decreased significantly after Abeta1-42 ejection. The changes in KA-evoked responses to Abeta1-42 revealed two types of cells. In the first type, the KA-mediated firing remained at the control level, while in the second type, Abeta1-42 attenuated the KA-evoked responses. A protective pentapeptide, Leu-Pro-Tyr-Phe-Asp-amide, was used to verify the specificity of these beta-amyloid-elicited effects. The pentapeptide protected against the modulatory effects of Abeta1-42 on the NMDA and AMPA responses. In conclusion, we have shown that Abeta1-42 exerts divergent effects on the activity of the ionotropic glutamate receptors in vivo. These results suggest that the LTP disruption and fEPSP attenuation seen after Abeta1-42 application are in part due to the altered function of these receptors.
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Affiliation(s)
- Viktor Szegedi
- Department of Medical Chemistry, Juhász Gyula College, University of Szeged, Dóm square 8, Szeged H-6720, Hungary.
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