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Abyadeh M, Gupta V, Paulo JA, Mahmoudabad AG, Shadfar S, Mirshahvaladi S, Gupta V, Nguyen CTO, Finkelstein DI, You Y, Haynes PA, Salekdeh GH, Graham SL, Mirzaei M. Amyloid-beta and tau protein beyond Alzheimer's disease. Neural Regen Res 2024; 19:1262-1276. [PMID: 37905874 DOI: 10.4103/1673-5374.386406] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 09/07/2023] [Indexed: 11/02/2023] Open
Abstract
ABSTRACT The aggregation of amyloid-beta peptide and tau protein dysregulation are implicated to play key roles in Alzheimer's disease pathogenesis and are considered the main pathological hallmarks of this devastating disease. Physiologically, these two proteins are produced and expressed within the normal human body. However, under pathological conditions, abnormal expression, post-translational modifications, conformational changes, and truncation can make these proteins prone to aggregation, triggering specific disease-related cascades. Recent studies have indicated associations between aberrant behavior of amyloid-beta and tau proteins and various neurological diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as retinal neurodegenerative diseases like Glaucoma and age-related macular degeneration. Additionally, these proteins have been linked to cardiovascular disease, cancer, traumatic brain injury, and diabetes, which are all leading causes of morbidity and mortality. In this comprehensive review, we provide an overview of the connections between amyloid-beta and tau proteins and a spectrum of disorders.
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Affiliation(s)
| | - Vivek Gupta
- Department of Clinical Medicine, Faculty of Medicine, Health and Human Sciences, Macquarie Medical School, Macquarie University, Macquarie Park, North Ryde, Sydney, NSW, Australia
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | | | - Sina Shadfar
- Department of Clinical Medicine, Faculty of Medicine, Health and Human Sciences, Macquarie Medical School, Macquarie University, Macquarie Park, North Ryde, Sydney, NSW, Australia
| | - Shahab Mirshahvaladi
- Department of Clinical Medicine, Faculty of Medicine, Health and Human Sciences, Macquarie Medical School, Macquarie University, Macquarie Park, North Ryde, Sydney, NSW, Australia
| | - Veer Gupta
- School of Medicine, Deakin University, Geelong, VIC, Australia
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, School of Health Sciences, Faculty of Medicine Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - David I Finkelstein
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Yuyi You
- Department of Clinical Medicine, Faculty of Medicine, Health and Human Sciences, Macquarie Medical School, Macquarie University, Macquarie Park, North Ryde, Sydney, NSW, Australia
| | - Paul A Haynes
- School of Natural Sciences, Macquarie University, Macquarie Park, NSW, Australia
| | - Ghasem H Salekdeh
- School of Natural Sciences, Macquarie University, Macquarie Park, NSW, Australia
| | - Stuart L Graham
- Department of Clinical Medicine, Faculty of Medicine, Health and Human Sciences, Macquarie Medical School, Macquarie University, Macquarie Park, North Ryde, Sydney, NSW, Australia
| | - Mehdi Mirzaei
- Department of Clinical Medicine, Faculty of Medicine, Health and Human Sciences, Macquarie Medical School, Macquarie University, Macquarie Park, North Ryde, Sydney, NSW, Australia
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Sokol DK, Lahiri DK. Neurodevelopmental disorders and microcephaly: how apoptosis, the cell cycle, tau and amyloid-β precursor protein APPly. Front Mol Neurosci 2023; 16:1201723. [PMID: 37808474 PMCID: PMC10556256 DOI: 10.3389/fnmol.2023.1201723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 08/08/2023] [Indexed: 10/10/2023] Open
Abstract
Recent studies promote new interest in the intersectionality between autism spectrum disorder (ASD) and Alzheimer's Disease. We have reported high levels of Amyloid-β Precursor Protein (APP) and secreted APP-alpha (sAPPa ) and low levels of amyloid-beta (Aβ) peptides 1-40 and 1-42 (Aβ40, Aβ42) in plasma and brain tissue from children with ASD. A higher incidence of microcephaly (head circumference less than the 3rd percentile) associates with ASD compared to head size in individuals with typical development. The role of Aβ peptides as contributors to acquired microcephaly in ASD is proposed. Aβ may lead to microcephaly via disruption of neurogenesis, elongation of the G1/S cell cycle, and arrested cell cycle promoting apoptosis. As the APP gene exists on Chromosome 21, excess Aβ peptides occur in Trisomy 21-T21 (Down's Syndrome). Microcephaly and some forms of ASD associate with T21, and therefore potential mechanisms underlying these associations will be examined in this review. Aβ peptides' role in other neurodevelopmental disorders that feature ASD and acquired microcephaly are reviewed, including dup 15q11.2-q13, Angelman and Rett syndrome.
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Affiliation(s)
- Deborah K. Sokol
- Section of Pediatrics, Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Debomoy K. Lahiri
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, United States
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, United States
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Head E, Helman AM, Powell D, Schmitt FA. Down syndrome, beta-amyloid and neuroimaging. Free Radic Biol Med 2018; 114:102-109. [PMID: 28935420 PMCID: PMC5748259 DOI: 10.1016/j.freeradbiomed.2017.09.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 09/12/2017] [Accepted: 09/14/2017] [Indexed: 12/20/2022]
Abstract
This review focuses on the role of Aβ in AD pathogenesis in Down syndrome and current approaches for imaging Aβ in vivo. We will describe how Aβ deposits with age, the posttranslational modifications that can occur, and detection in biofluids. Three unique case studies describing partial trisomy 21 cases without APP triplication, and the occurrences of low level mosaic trisomy 21 in an early onset AD patient are presented. Brain imaging for Aβ includes those by positron emission tomography and ligands (Pittsburgh Compound B, Florbetapir, and FDDNP) that bind Aβ have been published and are summarized here. In combination, we have learned a great deal about Aβ in DS in terms of characterizing age of onset of this pathology and it is exciting to note that there is a clinical trial in DS targeting Aβ that may lead to clinical benefits.
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Affiliation(s)
- Elizabeth Head
- University of Kentucky, Sanders-Brown Center on Aging, 800 South Limestone Street, Lexington, KY 40536, United States; University of Kentucky, Department of Pharmacology & Nutritional Sciences, Lexington, KY 40536, United States.
| | - Alex M Helman
- University of Kentucky, Sanders-Brown Center on Aging, 800 South Limestone Street, Lexington, KY 40536, United States; University of Kentucky, Department of Pharmacology & Nutritional Sciences, Lexington, KY 40536, United States; University of Kentucky, Magnetic Resonance Imaging and Spectroscopy Center, Lexington, KY 40536, United States; University of Kentucky, Department of Neurology, Lexington, KY 40536, United States
| | - David Powell
- University of Kentucky, Magnetic Resonance Imaging and Spectroscopy Center, Lexington, KY 40536, United States
| | - Frederick A Schmitt
- University of Kentucky, Sanders-Brown Center on Aging, 800 South Limestone Street, Lexington, KY 40536, United States; University of Kentucky, Department of Neurology, Lexington, KY 40536, United States
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Head E, Lott IT, Wilcock DM, Lemere CA. Aging in Down Syndrome and the Development of Alzheimer's Disease Neuropathology. Curr Alzheimer Res 2016; 13:18-29. [PMID: 26651341 PMCID: PMC4948181 DOI: 10.2174/1567205012666151020114607] [Citation(s) in RCA: 156] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/18/2015] [Accepted: 09/01/2015] [Indexed: 02/04/2023]
Abstract
Chromosome 21, triplicated in Down Syndrome, contains several genes that are thought to play a critical role in the development of AD neuropathology. The overexpression of the gene for the amyloid precursor protein (APP), on chromosome 21, leads to early onset beta-amyloid (Aβ) plaques in DS. In addition to Aβ accumulation, middle-aged people with DS develop neurofibrillary tangles, cerebrovascular pathology, white matter pathology, oxidative damage, neuroinflammation and neuron loss. There is also evidence of potential compensatory responses in DS that benefit the brain and delay the onset of dementia after there is sufficient neuropathology for a diagnosis of AD. This review describes some of the existing literature and also highlights gaps in our knowledge regarding AD neuropathology in DS. It will be critical in the future to develop networked brain banks with standardized collection procedures to fully characterize the regional and temporal pathological events associated with aging in DS. As more information is acquired regarding AD evolution in DS, there will be opportunities to develop interventions that are age-appropriate to delay AD in DS.
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Affiliation(s)
- Elizabeth Head
- Sanders Brown Center on Aging, University of Kentucky, 800 South Limestone Street, Lexington, KY, 40536, USA.
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Gamba P, Testa G, Gargiulo S, Staurenghi E, Poli G, Leonarduzzi G. Oxidized cholesterol as the driving force behind the development of Alzheimer's disease. Front Aging Neurosci 2015; 7:119. [PMID: 26150787 PMCID: PMC4473000 DOI: 10.3389/fnagi.2015.00119] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/03/2015] [Indexed: 12/21/2022] Open
Abstract
Alzheimer’s disease (AD), the most common neurodegenerative disorder associated with dementia, is typified by the pathological accumulation of amyloid Aβ peptides and neurofibrillary tangles (NFT) within the brain. Considerable evidence indicates that many events contribute to AD progression, including oxidative stress, inflammation, and altered cholesterol metabolism. The brain’s high lipid content makes it particularly vulnerable to oxidative species, with the consequent enhancement of lipid peroxidation and cholesterol oxidation, and the subsequent formation of end products, mainly 4-hydroxynonenal and oxysterols, respectively from the two processes. The chronic inflammatory events observed in the AD brain include activation of microglia and astrocytes, together with enhancement of inflammatory molecule and free radical release. Along with glial cells, neurons themselves have been found to contribute to neuroinflammation in the AD brain, by serving as sources of inflammatory mediators. Oxidative stress is intimately associated with neuroinflammation, and a vicious circle has been found to connect oxidative stress and inflammation in AD. Alongside oxidative stress and inflammation, altered cholesterol metabolism and hypercholesterolemia also significantly contribute to neuronal damage and to progression of AD. Increasing evidence is now consolidating the hypothesis that oxidized cholesterol is the driving force behind the development of AD, and that oxysterols are the link connecting the disease to altered cholesterol metabolism in the brain and hypercholesterolemia; this is because of the ability of oxysterols, unlike cholesterol, to cross the blood brain barrier (BBB). The key role of oxysterols in AD pathogenesis has been strongly supported by research pointing to their involvement in modulating neuroinflammation, Aβ accumulation, and cell death. This review highlights the key role played by cholesterol and oxysterols in the brain in AD pathogenesis.
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Affiliation(s)
- Paola Gamba
- Department of Clinical and Biological Sciences, School of Medicine, University of Turin Orbassano, Torino, Italy
| | - Gabriella Testa
- Department of Clinical and Biological Sciences, School of Medicine, University of Turin Orbassano, Torino, Italy
| | - Simona Gargiulo
- Department of Clinical and Biological Sciences, School of Medicine, University of Turin Orbassano, Torino, Italy
| | - Erica Staurenghi
- Department of Clinical and Biological Sciences, School of Medicine, University of Turin Orbassano, Torino, Italy
| | - Giuseppe Poli
- Department of Clinical and Biological Sciences, School of Medicine, University of Turin Orbassano, Torino, Italy
| | - Gabriella Leonarduzzi
- Department of Clinical and Biological Sciences, School of Medicine, University of Turin Orbassano, Torino, Italy
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Abstract
This chapter reviews the neurological phenotype of Down syndrome (DS) in early development, childhood, and aging. Neuroanatomic abnormalities in DS are manifested as aberrations in gross brain structure as well as characteristic microdysgenetic changes. As the result of these morphological abnormalities, brain circuitry is impaired. While an intellectual disability is ubiquitous in DS, there is a wide range of variation in cognitive performance and a growing understanding between aberrant brain circuitry and the cognitive phenotype. Hypotonia is most marked at birth, affecting gait and ligamentous laxity. Seizures are bimodal in presentation with infantile spasms common in infancy and generalized seizures associated with cognitive decline observed in later years. While all individuals have the characteristic neuropathology of Alzheimer's disease (AD) by age 40 years, the prevalence of dementia is not universal. The tendency to develop AD is related, in part, to several genes on chromosome 21 that are overexpressed in DS. Intraneuronal accumulation of β-amyloid appears to trigger a cascade of neurodegeneration resulting in the neuropathological and clinical manifestations of dementia. Functional brain imaging has elucidated the temporal sequence of amyloid deposition and glucose metabolic rate in the development of dementia in DS. Mitochondrial abnormalities contribute to oxidative stress which is part of AD pathogenesis in DS as well as AD in the general population. A variety of medical comorbidities threaten cognitive performance including sleep apnea, abnormalities in thyroid metabolism, and behavioral disturbances. Mouse models for DS are providing a platform for the formulation of clinical trials with intervention targeted to synaptic plasticity, brain biochemistry, and morphological brain alterations.
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Affiliation(s)
- Ira T Lott
- Department of Pediatrics and Neurology, School of Medicine, University of California Irvine (UCI), Orange, CA, USA.
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Lott IT, Doran E, Nguyen VQ, Tournay A, Head E, Gillen DL. Down syndrome and dementia: a randomized, controlled trial of antioxidant supplementation. Am J Med Genet A 2011; 155A:1939-48. [PMID: 21739598 DOI: 10.1002/ajmg.a.34114] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 04/22/2011] [Indexed: 01/03/2023]
Abstract
Individuals with Down syndrome over age 40 years are at risk for developing dementia of the Alzheimer type and have evidence for chronic oxidative stress. There is a paucity of treatment trials for dementia in Down syndrome in comparison to Alzheimer disease in the general (non-Down syndrome) population. This 2-year randomized, double-blind, placebo-controlled trial assessed whether daily oral antioxidant supplementation (900 IU of alpha-tocopherol, 200 mg of ascorbic acid and 600 mg of alpha-lipoic acid) was effective, safe and tolerable for 53 individuals with Down syndrome and dementia. The outcome measures comprised a battery of neuropsychological assessments administered at baseline and every 6 months. Compared to the placebo group, those individuals receiving the antioxidant supplement showed neither an improvement in cognitive functioning nor a stabilization of cognitive decline. Mean plasma levels of alpha-tocopherol increased ~2-fold in the treatment group and were consistently higher than the placebo group over the treatment period. Pill counts indicated good compliance with the regimen. No serious adverse events attributed to the treatment were noted. We conclude that antioxidant supplementation is safe, though ineffective as a treatment for dementia in individuals with Down syndrome and Alzheimer type dementia. Our findings are similar to studies of antioxidant supplementation in Alzheimer disease in the general population. The feasibility of carrying out a clinical trial for dementia in Down syndrome is demonstrated.
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Affiliation(s)
- Ira T Lott
- Department of Pediatrics, School of Medicine, University of California, Irvine (UCI), Orange, California, USA.
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8
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A role for synaptic zinc in activity-dependent Abeta oligomer formation and accumulation at excitatory synapses. J Neurosci 2009; 29:4004-15. [PMID: 19339596 DOI: 10.1523/jneurosci.5980-08.2009] [Citation(s) in RCA: 175] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Soluble amyloid beta oligomers (AbetaOs) interfere with synaptic function and bind with high affinity to synapses, but the mechanism underlying AbetaO synaptic targeting is not known. Here, we show that the accumulation of synthetic or native Alzheimer's disease (AD)-brain oligomers at synapses is regulated by synaptic activity. Electrical or chemical stimulation increased AbetaO synaptic localization and enhanced oligomer formation at synaptic terminals, whereas inhibition with TTX blocked AbetaO synaptic localization and reduced AbetaO synaptic load. The zinc-binding 8-OH-quinoline clioquinol markedly reduced AbetaO synaptic targeting, which was also reduced in brain sections of animals deficient in the synaptic vesicle zinc transporter ZnT3, indicating that vesicular zinc released during neurotransmission is critical for AbetaO synaptic targeting. Oligomers were not internalized in recycled vesicles but remained at the cell surface, where they colocalized with NR2B NMDA receptor subunits. Furthermore, NMDA antagonists blocked AbetaO synaptic targeting, implicating excitatory receptor activity in oligomer formation and accumulation at synapses. In AD brains, oligomers of different size colocalized with synaptic markers in hippocampus and cortex, where oligomer synaptic accumulation correlated with synaptic loss.
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Smith DG, Cappai R, Barnham KJ. The redox chemistry of the Alzheimer's disease amyloid beta peptide. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1976-90. [PMID: 17433250 DOI: 10.1016/j.bbamem.2007.02.002] [Citation(s) in RCA: 449] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 02/02/2007] [Accepted: 02/05/2007] [Indexed: 12/28/2022]
Abstract
There is a growing body of evidence to support a role for oxidative stress in Alzheimer's disease (AD), with increased levels of lipid peroxidation, DNA and protein oxidation products (HNE, 8-HO-guanidine and protein carbonyls respectively) in AD brains. The brain is a highly oxidative organ consuming 20% of the body's oxygen despite accounting for only 2% of the total body weight. With normal ageing the brain accumulates metals ions such iron (Fe), zinc (Zn) and copper (Cu). Consequently the brain is abundant in antioxidants to control and prevent the detrimental formation of reactive oxygen species (ROS) generated via Fenton chemistry involving redox active metal ion reduction and activation of molecular oxygen. In AD there is an over accumulation of the Amyloid beta peptide (Abeta), this is the result of either an elevated generation from amyloid precursor protein (APP) or inefficient clearance of Abeta from the brain. Abeta can efficiently generate reactive oxygen species in the presence of the transition metals copper and iron in vitro. Under oxidative conditions Abeta will form stable dityrosine cross-linked dimers which are generated from free radical attack on the tyrosine residue at position 10. There are elevated levels of urea and SDS resistant stable linked Abeta oligomers as well as dityrosine cross-linked peptides and proteins in AD brain. Since soluble Abeta levels correlate best with the degree of degeneration [C.A. McLean, R.A. Cherny, F.W. Fraser, S.J. Fuller, M.J. Smith, K. Beyreuther, A.I. Bush, C.L. Masters, Soluble pool of Abeta amyloid as a determinant of severity of neurodegeneration in Alzheimer's disease, Ann. Neurol. 46 (1999) 860-866] we suggest that the toxic Abeta species corresponds to a soluble dityrosine cross-linked oligomer. Current therapeutic strategies using metal chelators such as clioquinol and desferrioxamine have had some success in altering the progression of AD symptoms. Similarly, natural antioxidants curcumin and ginkgo extract have modest but positive effects in slowing AD development. Therefore, drugs that target the oxidative pathways in AD could have genuine therapeutic efficacy.
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Affiliation(s)
- Danielle G Smith
- Department of Pathology, The University of Melbourne, Parkville, Victoria 3010, Australia
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Heredia L, Helguera P, de Olmos S, Kedikian G, Solá Vigo F, LaFerla F, Staufenbiel M, de Olmos J, Busciglio J, Cáceres A, Lorenzo A. Phosphorylation of actin-depolymerizing factor/cofilin by LIM-kinase mediates amyloid beta-induced degeneration: a potential mechanism of neuronal dystrophy in Alzheimer's disease. J Neurosci 2006; 26:6533-42. [PMID: 16775141 PMCID: PMC6674046 DOI: 10.1523/jneurosci.5567-05.2006] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Deposition of fibrillar amyloid beta (fAbeta) plays a critical role in Alzheimer's disease (AD). We have shown recently that fAbeta-induced dystrophy requires the activation of focal adhesion proteins and the formation of aberrant focal adhesion structures, suggesting the activation of a mechanism of maladaptative plasticity in AD. Focal adhesions are actin-based structures that provide a structural link between the extracellular matrix and the cytoskeleton. To gain additional insight in the molecular mechanism of neuronal degeneration in AD, here we explored the involvement of LIM kinase 1 (LIMK1), actin-depolymerizing factor (ADF), and cofilin in Abeta-induced dystrophy. ADF/cofilin are actin-binding proteins that play a central role in actin filament dynamics, and LIMK1 is the kinase that phosphorylates and thereby inhibits ADF/cofilin. Our data indicate that treatment of hippocampal neurons with fAbeta increases the level of Ser3-phosphorylated ADF/cofilin and Thr508-phosphorylated LIMK1 (P-LIMK1), accompanied by a dramatic remodeling of actin filaments, neuritic dystrophy, and neuronal cell death. A synthetic peptide, S3 peptide, which acts as a specific competitor for ADF/cofilin phosphorylation by LIMK1, inhibited fAbeta-induced ADF/cofilin phosphorylation, preventing actin filament remodeling and neuronal degeneration, indicating the involvement of LIMK1 in Abeta-induced neuronal degeneration in vitro. Immunofluorescence analysis of AD brain showed a significant increase in the number of P-LIMK1-positive neurons in areas affected with AD pathology. P-LIMK1-positive neurons also showed early signs of AD pathology, such as intracellular Abeta and pretangle phosphorylated tau. Thus, LIMK1 activation may play a key role in AD pathology.
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Helguera P, Pelsman A, Pigino G, Wolvetang E, Head E, Busciglio J. ets-2 promotes the activation of a mitochondrial death pathway in Down's syndrome neurons. J Neurosci 2006; 25:2295-303. [PMID: 15745955 PMCID: PMC6726094 DOI: 10.1523/jneurosci.5107-04.2005] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Down's syndrome (DS) is characterized by mental retardation and development of Alzheimer's disease (AD). Oxidative stress and mitochondrial dysfunction are both related to neurodegeneration in DS. Several genes in chromosome 21 have been linked to neuronal death, including the transcription factor ets-2. Cortical cultures derived from normal and DS fetal brains were used to study the role of ets-2 in DS neuronal degeneration. ets-2 was expressed in normal human cortical neurons (HCNs) and was markedly upregulated by oxidative stress. When overexpressed in normal HCNs, ets-2 induced a stereotyped sequence of apoptotic changes leading to neuronal death. DS HCNs exhibit intracellular oxidative stress and increased apoptosis after the first week in culture (Busciglio and Yankner, 1995). ets-2 levels were increased in DS HCNs, and, between 7 and 14 d in vitro, DS HCNs showed increased bax, cytoplasmic translocation of cytochrome c and apoptosis inducing factor, and active caspases 3 and 7, consistent with activation of an apoptotic mitochondrial death pathway. Degeneration of DS neurons was reduced by dominant-negative ets-2, suggesting that increased ets-2 expression promotes DS neuronal apoptosis. In the human brain, ets-2 expression was found in neurons and astrocytes. Strong ets-2 immunoreactivity was observed in DS/AD and sporadic AD brains associated with degenerative markers such as bax, intracellular Abeta, and hyperphosphorylated tau. Thus, in DS/AD and sporadic AD brains, converging pathological mechanisms leading to chronic oxidative stress and ets-2 upregulation in susceptible neurons may result in increased vulnerability by promoting the activation of a mitochondrial-dependent proapoptotic pathway of cell death.
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Affiliation(s)
- Pablo Helguera
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, California 92697-4550, USA
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Lott IT, Head E. Alzheimer disease and Down syndrome: factors in pathogenesis. Neurobiol Aging 2005; 26:383-9. [PMID: 15639317 DOI: 10.1016/j.neurobiolaging.2004.08.005] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2004] [Revised: 07/29/2004] [Accepted: 08/26/2004] [Indexed: 11/20/2022]
Abstract
There is evidence to suggest that certain shared features exist in the pathogenesis of vascular disease and Alzheimer disease (AD) in the general population. In Down syndrome (DS) all adults over the age of 40 years develop sufficient neuropathology for a diagnosis of AD. However, vascular disease is not as common in DS as it is in the general population, particularly with respect to the development of atheromas. We discuss biological mechanisms and risk factors that may be common to both diseases including cholesterol metabolism, inflammation, plasminogen activator inhibitor and apolipoprotein E (Apo E). The study of individuals with DS may help to identify common pathogenic links as well as a disassociation between vascular disease and AD.
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Affiliation(s)
- Ira T Lott
- Institute for Brain Aging and Dementia, University of California, Irvine, CA 92697, USA.
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Finch CE. Developmental origins of aging in brain and blood vessels: an overview. Neurobiol Aging 2005; 26:281-91. [PMID: 15639305 DOI: 10.1016/j.neurobiolaging.2004.03.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Revised: 03/17/2004] [Accepted: 03/30/2004] [Indexed: 01/22/2023]
Abstract
Emerging evidence suggests a remarkable convergence of inflammatory mechanisms in the etiology of cardiovascular disease and Alzheimer disease. A broad set of NSAIDs and statins used to reduce the risk of vascular occlusion and to slow atherogensis may also be protective for Alzheimer disease. Elevated blood levels of C-reactive protein are risk factors for cardiovascular disease and possibly for Alzheimer disease. Monocyte-lineage cells are also fundamental to both conditions: in blood vessels, macrophages are important to atherogenesis for the accumulation of lipids (foam cells), whereas brain microglia show activation during aging and direct involvement in amyloid metabolism in the senile plaque. Genetic influences are recognized through the apoE4 allele, which is associated with hypercholesterolemia and is a risk factor in vascular events and Alzheimer disease, and is recognized for its proinflammatory profile. ApoE4 also accelerates Alzheimer disease pathogenesis in Down's syndrome and many other chronic neurodegenerative conditions, as is well-supported by animal models. Inflammatory changes are present at the earliest stages of vascular disease and Down's syndrome in human fetuses, and are also prominent early in Alzheimer disease. These findings give a basis for considering inflammatory processes early in life which can lead to fully fired pathogenesis of cardiovascular disease and possibly for Alzheimer disease.
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Affiliation(s)
- Caleb E Finch
- Department of Biological Sciences, Andrus Gerontology Center, University of Southern California, Los Angeles, CA 90089-0191, USA.
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Abstract
PURPOSE OF REVIEW Exciting new therapeutic approaches to the treatment or prevention of Alzheimer's disease involve preventing, slowing or reversing beta-amyloid accumulation. These interventions may also apply to the treatment of Alzheimer's disease in Down syndrome. The purpose of the current review is therefore to summarize developments and advances in our understanding of beta-amyloid pathogenesis in Down syndrome over the past year. RECENT FINDINGS A shift in research to a focus on early events in beta-amyloid pathogenesis in Down syndrome has led to several novel observations. Several authors have reported the accumulation of both soluble and intracellular beta-amyloid before extracellular beta-amyloid (senile plaques) in Down syndrome. Increases in beta-amyloid levels in Down syndrome may reflect the increased expression and protein levels of beta-site amyloid precursor protein cleavage enzyme 2 on chromosome 21. The impact of the accumulation of beta-amyloid may have differential effects on development and aging in Down syndrome. SUMMARY The past year has seen significant advances in our understanding of beta-amyloid pathogenesis and the functional consequences of beta-amyloid accumulation in Down syndrome. However, there are still large gaps in our knowledge of the pathways involved in beta-amyloid degradation and clearance. It will be critical to conduct clinical trials to test therapeutic strategies that may reduce beta-amyloid in Down syndrome directly to determine the optimal age and dose for specific interventions. Given the differences in the mechanism of beta-amyloid accumulation in Down syndrome, careful consideration needs to be given to potential clinical trials to treat this disorder.
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Affiliation(s)
- Elizabeth Head
- Institute for Brain Aging and Dementia, Department of Neurology, University of California, Irvine, California, USA.
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Wolvetang EJ, Bradfield OM, Hatzistavrou T, Crack PJ, Busciglio J, Kola I, Hertzog PJ. Overexpression of the chromosome 21 transcription factor Ets2 induces neuronal apoptosis. Neurobiol Dis 2003; 14:349-56. [PMID: 14678752 DOI: 10.1016/s0969-9961(03)00107-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Down syndrome (trisomy 21) neurons display an increased rate of apoptosis in vitro. The genes on chromosome 21 that mediate this increased cell death remain to be elucidated. Here we show that the chromosome 21 transcription factor Ets2, a gene that is overexpressed in Down syndrome, is expressed in neurons, and that moderate overexpression of Ets2 leads to increased apoptosis of primary neuronal cultures from Ets2 tg mice that involves activation of caspase-3. Our data therefore suggest that overexpression of ETS2 may contribute to the increased rate of apoptosis of neurons in Down syndrome.
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Affiliation(s)
- E J Wolvetang
- Monash Institute of Reproduction and Development, Monash University, Monash Medical Center, 246 Clayton Road, 3168 Clayton, Australia.
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Abstract
Caspases are a group of cysteine dependent aspartate-specific proteases. Originally found as the homolog of Ced-3 in C. elegans, 14 caspases have now been identified in mammals to date. Caspases play important roles in both the intrinsic and extrinsic apoptotic pathways and interact with the non-caspase apoptotic pathways. A number of recent published observations have suggested a strong association between apoptosis, age-related diseases and aging. Findings from our group and others reveal a strong correlation between alterations in caspase activity and aging. In this view point, we summarize current knowledge of the connection between caspases and aging observed in a variety of model systems from cultured cells in vitro to the in vivo models of rodents and humans.
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Affiliation(s)
- Jian-Hua Zhang
- Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
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17
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Yoburn JC, Tian W, Brower JO, Nowick JS, Glabe CG, Van Vranken DL. Dityrosine cross-linked Abeta peptides: fibrillar beta-structure in Abeta(1-40) is conducive to formation of dityrosine cross-links but a dityrosine cross-link in Abeta(8-14) does not induce beta-structure. Chem Res Toxicol 2003; 16:531-5. [PMID: 12703970 DOI: 10.1021/tx025666g] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent reports by Galeazzi and co-workers demonstrated the susceptibility of Abeta(1-42) to undergo dityrosine formation via peroxidase-catalyzed tyrosine cross-linking. We have formed dityrosine cross-links in Abeta(1-40) using these enzymatic conditions as well as a copper-H(2)O(2) method. The efficiency of dityrosine cross-link formation is strongly influenced by the aggregation state of Abeta; more dityrosine is formed when copper-H(2)O(2) or horseradish peroxidase-catalyzed oxidation is applied to fibrillar Abeta vs soluble Abeta. Once formed, dityrosine cross-links are susceptible to further oxidative processes and it appears that cross-links formed in soluble Abeta react through these pathways more readily than those formed in fibrillar Abeta. Because preorganization of fibrils affects the efficiency of dityrosine formation, we examined the effect of dityrosine formation upon local peptide conformation by assessing the solution structure of a small dityrosine dimer derived from Abeta(8-14). Two-dimensional (1)H NMR studies of the short dityrosine dimer offer no evidence of structure. Thus, the fibrillar structure of Abeta enhances formation of dityrosine cross-links, but dityrosine cross-links do not seem to enhance local secondary structure.
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Affiliation(s)
- Joshua C Yoburn
- Department of Chemistry, University of California, Irvine, California 92697, USA
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