101
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Wang S, Jia J. Promoter polymorphisms which modulate BACE1 expression are associated with sporadic Alzheimer's disease. Am J Med Genet B Neuropsychiatr Genet 2010; 153B:159-66. [PMID: 19441127 DOI: 10.1002/ajmg.b.30968] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Beta-site APP-cleaving enzyme 1 (BACE1) gene has been suggested as a candidate gene for Alzheimer's disease (AD). However, little is known regarding the effects of polymorphisms in regulatory sequences of BACE1 on AD susceptibility. To evaluate the relationship between polymorphisms in the BACE1 promoter and sporadic AD (SAD) genetically and functionally, we performed a case-control study (429 cases and 346 controls of Han Chinese descent) and functional characterization of the polymorphisms in vitro using luciferase assay and electrophoretic mobility shift assay (EMSA). Two polymorphisms (-918G/A, rs4938369; -2014T/C, rs3017608) were identified in the BACE1 promoter. The results showed that the -918G/A polymorphism was associated with SAD and the -918GG carriers had a 1.67-fold higher risk for SAD than the carriers with -918AA and GA genotypes (OR = 1.667, 95% CI = 1.087-2.556, P = 0.019). The haplotype -918G/-2014T may be a possible risk factor for SAD (P = 0.016). Luciferase reporter assays showed the -918G allele and its resultant haplotype -918G/-2014T induced an increase of transcriptional activity. A more marked increase in -918G/-2014T transcriptional activity was seen when under hypoxia treatment. EMSA indicated that the -918G allele bound nuclear factors more strongly than -918A allele did. Our findings suggest that the BACE1 promoter polymorphisms which regulate BACE1 expression may contribute to SAD susceptibility. Further independent studies are required to verify our findings.
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Affiliation(s)
- Shan Wang
- Department of Neurology, Xuan Wu Hospital of the Capital Medical University, Beijing, China
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102
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Griffin WST, Barger SW. Neuroinflammatory Cytokines-The Common Thread in Alzheimer's Pathogenesis. US NEUROLOGY 2010; 6:19-27. [PMID: 22408651 PMCID: PMC3297620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This article discusses the potential role of the cytokine cycle and its corollary as drivers of the relentless progression of Alzheimer's neuropathologies, whether they are the result of gene mutations, gene polymorphisms, and/or environmental and comorbid conditions. Based on the discovery of cytokine overexpression as an accompaniment to the dementia-related glial activation, the cytokine hypothesis was proposed. This states that in response to the negative impact on neurons of known and unknown risk factors-which include genetic inheritance, comorbid and environmental factors-microglia and astrocytes become activated and produce excess amounts of the immune-modulating cytokine interleukin-1 (IL-1) and the neuritogenic cytokine S100B, respectively. Finding that these glial events occur in fetuses and neonates with Down syndrome provided the first evidence that productive immune responses by activated glia precede rather than follow overt AD-related pathology. This finding can be added to the demonstration of IL-1 induction of amyloid β (Aβ) precursor protein and astrocyte activation with excess production of neuritogenic factor S100B. This combination suggests that IL-1 and S100B overexpression would favor the Aβ production and dystrophic neurite growth necessary for laying down neuritic Aβ plaques. This, together with demonstration of IL-1 induction of excessive production of the precursors of other features common in AD prompted a corollary to the cytokine hypothesis. The corollary states that regardless of the primary cause of the neuronal insult, the result will be chronic glial activation, which in turn will result in further neuronal injury, still more glial activation with excess cytokine expression and so on. This article discusses known causes, genetic and environmental risk factors, and comorbid conditions, and the potential contribution of glial activation with excessive cytokine expression to each.
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Affiliation(s)
- W Sue T Griffin
- Dillard Professor and Vice Chairman, Donald W Reynolds Department of Geriatrics and the Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, and Geriatric Research, Education and Clinical Center, Central Arkansas Veterans HealthCare System
| | - Steven W Barger
- Professor of Geriatrics, Neurobiology and Developmental Sciences and Internal Medicine, Donald W Reynolds Department of Geriatrics and the Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, and Geriatric Research, Education and Clinical Center, Central Arkansas Veterans HealthCare System
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103
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Eacker SM, Dawson TM, Dawson VL. Understanding microRNAs in neurodegeneration. Nat Rev Neurosci 2009; 10:837-41. [PMID: 19904280 DOI: 10.1038/nrn2726] [Citation(s) in RCA: 227] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Interest in the functions of microRNAs (miRNAs) in the nervous system has recently expanded to include their roles in neurodegeneration. Investigations have begun to reveal the influence of miRNAs on both neuronal survival and the accumulation of toxic proteins that are associated with neurodegeneration, and are providing clues as to how these toxic proteins can influence miRNA expression.
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Affiliation(s)
- Stephen M Eacker
- Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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104
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Bettens K, Brouwers N, Engelborghs S, Van Miegroet H, De Deyn PP, Theuns J, Sleegers K, Van Broeckhoven C. APPandBACE1miRNA genetic variability has no major role in risk for Alzheimer disease. Hum Mutat 2009; 30:1207-13. [DOI: 10.1002/humu.21027] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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105
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Rademakers R, Rovelet-Lecrux A. Recent insights into the molecular genetics of dementia. Trends Neurosci 2009; 32:451-61. [PMID: 19640594 DOI: 10.1016/j.tins.2009.05.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 05/17/2009] [Accepted: 05/18/2009] [Indexed: 12/12/2022]
Abstract
Our understanding of the molecular genetic basis of two common neurodegenerative dementias, Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD), has greatly advanced in recent years. Progranulin mutations were identified as a major cause of FTLD and a potential susceptibility factor for other forms of dementia. In addition, through copy-number analyses of previously identified disease genes and the study of microRNA regulation in dementia, new evidence emerged to support the view that subtle variability in the expression of known disease proteins could increase the risk for sporadic forms of dementia. Finally, in late-onset AD populations, the first genome-wide association studies were performed and novel potential AD susceptibility genes reported. These exciting findings provide novel insights into the disease mechanisms underlying dementia and hold promise for the development of potential treatments.
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Affiliation(s)
- Rosa Rademakers
- Mayo Clinic, Department of Neuroscience, Jacksonville, FL 32224, USA.
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106
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Huttunen HJ, Peach C, Bhattacharyya R, Barren C, Pettingell W, Hutter-Paier B, Windisch M, Berezovska O, Kovacs DM. Inhibition of acyl-coenzyme A: cholesterol acyl transferase modulates amyloid precursor protein trafficking in the early secretory pathway. FASEB J 2009; 23:3819-28. [PMID: 19625658 DOI: 10.1096/fj.09-134999] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Amyloid beta-peptide (Abeta) has a central role in the pathogenesis of Alzheimer's disease (AD). Cellular cholesterol homeostasis regulates endoproteolytic generation of Abeta from the amyloid precursor protein (APP). Previous studies have identified acyl-coenzyme A: cholesterol acyltransferase (ACAT), an enzyme that regulates subcellular cholesterol distribution, as a potential therapeutic target for AD. Inhibition of ACAT activity decreases Abeta generation in cell- and animal-based models of AD through an unknown mechanism. Here we show that ACAT inhibition retains a fraction of APP molecules in the early secretory pathway, limiting the availability of APP for secretase-mediated proteolytic processing. ACAT inhibitors delayed the trafficking of immature APP molecules from the endoplasmic reticulum (ER) as shown by metabolic labeling and live-cell imaging. This resulted in partial ER retention of APP and enhanced ER-associated degradation of APP by the proteasome, without activation of the unfolded protein response pathway. The ratio of mature APP to immature APP was reduced in brains of mice treated with ACAT inhibitors, and strongly correlated with reduced brain APP-C99 and cerebrospinal fluid Abeta levels in individual animals. Our results identify a novel ACAT-dependent mechanism that regulates secretory trafficking of APP, likely contributing to decreased Abeta generation in vivo.
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Affiliation(s)
- Henri J Huttunen
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, Massachusetts General Hospital, Harvard Medical School, 114 16th Street, Charlestown, MA 02129, USA
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107
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Allele-specific RNAi mitigates phenotypic progression in a transgenic model of Alzheimer's disease. Mol Ther 2009; 17:1563-73. [PMID: 19532137 DOI: 10.1038/mt.2009.123] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Despite recent advances suggesting new therapeutic targets, Alzheimer's disease (AD) remains incurable. Aberrant production and accumulation of the Abeta peptide resulting from altered processing of the amyloid precursor protein (APP) is central to the pathogenesis of disease, particularly in dominantly inherited forms of AD. Thus, modulating the production of APP is a potential route to effective AD therapy. Here, we describe the successful use of an allele-specific RNA interference (RNAi) approach targeting the Swedish variant of APP (APPsw) in a transgenic mouse model of AD. Using recombinant adeno-associated virus (rAAV), we delivered an anti-APPsw short-hairpin RNA (shRNA) to the hippocampus of AD transgenic mice (APP/PS1). In short- and long-term transduction experiments, reduced levels of APPsw transprotein were observed throughout targeted regions of the hippocampus while levels of wild-type murine APP remained unaltered. Moreover, intracellular production of transfer RNA (tRNA)-valine promoter-driven shRNAs did not lead to detectable neuronal toxicity. Finally, long-term bilateral hippocampal expression of anti-APPsw shRNA mitigated abnormal behaviors in this mouse model of AD. The difference in phenotype progression was associated with reduced levels of soluble Abeta but not with a reduced number of amyloid plaques. Our results support the development of allele-specific RNAi strategies to treat familial AD and other dominantly inherited neurodegenerative diseases.
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108
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Association between promoter polymorphisms of the nicastrin gene and sporadic Alzheimer's disease in North Chinese Han population. Neurosci Lett 2009; 458:136-9. [PMID: 19394408 DOI: 10.1016/j.neulet.2009.04.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 04/03/2009] [Accepted: 04/21/2009] [Indexed: 11/22/2022]
Abstract
Increasing evidences have shown that nicastrin (NCSTN) plays a crucial role in gamma-cleavage of the amyloid precursor protein (APP). Inhibition of NCSTN demonstrated an altered gamma-cleavage activity, suggesting its potential implication in developing Alzheimer's disease (AD). We detected the NCSTN gene promoter region in 359 sporadic AD (SAD) patients and 331 controls and found three promoter single nucleotide polymorphisms (SNPs): -1216C/A (rs2147471), -796T/G (rs10752637) and -436C/T (rs1324738). For -1216C/A, there were significant differences in the allele and genotype frequency between AD and control subjects (allele P=0.031, genotype P=0.017). The allele and genotype frequencies remained significant before and after APOEvarepsilon4 stratification. The -1216CC carriers increased 2-fold risk for the development of SAD compared to the carriers with -1216CA and AA genotypes (OR=2.049, 95%CI=1.410-2.976, P=0.000). For -796T/G, there were significant differences in the genotype frequency between SAD and control subjects (P=0.009). This trend is still obvious in the subjects without APOEvarepsilon4 allele. The -796GG carriers might decrease the risk compared to the carriers with -796TG and TT genotypes (OR=0.602, 95%CI=0.393-0.932, P=0.022). No significant difference was detected either in genotype or in allele frequencies between SAD and control for -436C/T, even after APOEvarepsilon4 stratification. The haplotype -1216A/-796G may be a protective factor for SAD (OR=0.795, 95%CI=0.636-0.995, P=0.045). Our investigation suggests that -1216C/A and -796T/G are probably related to the development of SAD.
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109
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Abstract
Copy number variation (CNV) is a source of genetic diversity in humans. Numerous CNVs are being identified with various genome analysis platforms, including array comparative genomic hybridization (aCGH), single nucleotide polymorphism (SNP) genotyping platforms, and next-generation sequencing. CNV formation occurs by both recombination-based and replication-based mechanisms and de novo locus-specific mutation rates appear much higher for CNVs than for SNPs. By various molecular mechanisms, including gene dosage, gene disruption, gene fusion, position effects, etc., CNVs can cause Mendelian or sporadic traits, or be associated with complex diseases. However, CNV can also represent benign polymorphic variants. CNVs, especially gene duplication and exon shuffling, can be a predominant mechanism driving gene and genome evolution.
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Affiliation(s)
- Feng Zhang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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110
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Hébert SS, Horré K, Nicolaï L, Bergmans B, Papadopoulou AS, Delacourte A, De Strooper B. MicroRNA regulation of Alzheimer's Amyloid precursor protein expression. Neurobiol Dis 2008; 33:422-8. [PMID: 19110058 DOI: 10.1016/j.nbd.2008.11.009] [Citation(s) in RCA: 314] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 11/14/2008] [Accepted: 11/25/2008] [Indexed: 01/07/2023] Open
Abstract
Gene dosage effects of Amyloid precursor protein (APP) can cause familial AD. Recent evidence suggest that microRNA (miRNA) pathways, implicated in gene transcriptional control, could be involved in the development of sporadic Alzheimer's disease (AD). We therefore investigated whether miRNAs could participate in the regulation of APP gene expression. We show that miRNAs belonging to the miR-20a family (that is, miR-20a, miR-17-5p and miR-106b) could regulate APP expression in vitro and at the endogenous level in neuronal cell lines. A tight correlation between these miRNAs and APP was found during brain development and in differentiating neurons. We thus identify miRNAs as novel endogenous regulators of APP expression, suggesting that variations in miRNA expression could contribute to changes in APP expression in the brain during development and disease. This possibility is further corroborated by the observation that a statistically significant decrease in miR-106b expression was found in sporadic AD patients.
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111
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Simón AM, Schiapparelli L, Salazar-Colocho P, Cuadrado-Tejedor M, Escribano L, López de Maturana R, Del Río J, Pérez-Mediavilla A, Frechilla D. Overexpression of wild-type human APP in mice causes cognitive deficits and pathological features unrelated to Abeta levels. Neurobiol Dis 2008; 33:369-78. [PMID: 19101630 DOI: 10.1016/j.nbd.2008.11.005] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 10/30/2008] [Accepted: 11/07/2008] [Indexed: 01/07/2023] Open
Abstract
Transgenic mice expressing mutant human amyloid precursor protein (APP) develop an age-dependent amyloid pathology and memory deficits, but no overt neuronal loss. Here, in mice overexpressing wild-type human APP (hAPP(wt)) we found an early memory impairment, particularly in the water maze and to a lesser extent in the object recognition task, but beta-amyloid peptide (Abeta(42)) was barely detectable in the hippocampus. In these mice, hAPP processing was basically non-amyloidogenic, with high levels of APP carboxy-terminal fragments, C83 and APP intracellular domain. A tau pathology with an early increase in the levels of phosphorylated tau in the hippocampus, a likely consequence of enhanced ERK1/2 activation, was also observed. Furthermore, these mice presented a loss of synapse-associated proteins: PSD95, AMPA and NMDA receptor subunits and phosphorylated CaMKII. Importantly, signs of neurodegeneration were found in the hippocampal CA1 subfield and in the entorhinal cortex that were associated to a marked loss of MAP2 immunoreactivity. Conversely, in mice expressing mutant hAPP, high levels of Abeta(42) were found in the hippocampus, but no signs of neurodegeneration were apparent. The results support the notion of Abeta-independent pathogenic pathways in Alzheimer's disease.
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Affiliation(s)
- Ana-María Simón
- Division of Neurosciences, CIMA, University of Navarra, Av. Pio XII 55, 31008 Pamplona, Spain
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112
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McAlpine FE, Tansey MG. Neuroinflammation and tumor necrosis factor signaling in the pathophysiology of Alzheimer's disease. J Inflamm Res 2008; 1:29-39. [PMID: 22096345 PMCID: PMC3218716 DOI: 10.2147/jir.s4397] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects nearly one in two individuals over 90 years of age. Its neuropathological hallmarks are accumulation of extraneuronal plaques of amyloid-beta (Aβ), the presence of neurofibrillary tangles formed by aberrantly hyperphosphorylated tau, progressive synaptic loss, and neurodegeneration which eventually results in decline of memory and cognitive faculties. Although the etiology of sporadic AD in humans is unknown, mutations in amyloid precursor protein or components of its processing machinery (β-secretase and γ-secretase) result in overproduction of Aβ1-40 and 1-42 peptides and are sufficient to cause disease. In this review, we highlight the experimental and clinical evidence that suggests a close association between neuro-inflammation and AD pathogenesis. Overproduction of inflammatory mediators in the brain occurs when microglia, which are often found in close physical association with amyloid plaques in AD brains, become chronically activated. It has been proposed that elevated levels of pro-inflammatory cytokines, including tumor necrosis factor (TNF), may inhibit phagocytosis of Aβ in AD brains thereby hindering efficient plaque removal by resident microglia. In support of this idea, the bacterial endotoxin lipopolysaccharide, a potent trigger of inflammation that elicits production of TNF and many other cytokines, can accelerate the appearance and severity of AD pathology in several animal models of AD. We review the evidence implicating TNF signaling in AD pathology and discuss how TNF-dependent processes may contribute to cognitive dysfunction and accelerated progression of AD. We conclude by reviewing the observations that provide compelling rationale to investigate the extent to which new therapeutic approaches that selectively target the TNF pathway modify progression of neuropathology in pre-clinical models of AD as well as the promising findings with the use of nonsteroidal anti-inflammatory drugs and recent clinical trials with Aβ immunotherapy.
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Affiliation(s)
| | - Malú G Tansey
- Correspondence: Malú G Tansey, Department of Physiology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA, Tel +1 214 645 6037, Fax +1 214 645 6049, Email
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113
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RIBE EM, SERRANO-SAIZ E, AKPAN N, TROY CM. Mechanisms of neuronal death in disease: defining the models and the players. Biochem J 2008; 415:165-182. [PMID: 18800967 PMCID: PMC9334905 DOI: 10.1042/bj20081118] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
Dysregulation of life and death at the cellular level leads to a variety of diseases. In the nervous system, aberrant neuronal death is an outstanding feature of neurodegenerative diseases. Since the discovery of the caspase family of proteases, much effort has been made to determine how caspases function in disease, including neurodegenerative diseases. Although many papers have been published examining caspases in neuronal death and disease, the pathways have not been fully clarified. In the present review, we examine the potential players in the death pathways, the current tools for examining these players and the models for studying neurological disease. Alzheimer's disease, the most common neurodegenerative disorder, and cerebral ischaemia, the most common cause of neurological death, are used to illustrate our current understanding of death signalling in neurodegenerative diseases. A better understanding of the neuronal death pathways would provide targets for the development of therapeutic interventions for these diseases.
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Affiliation(s)
- Elena M. RIBE
- Departments of Pathology and Neurology, Taub Center for the Study of Alzheimer’s Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, 630 W. 168th Street, New York, NY 10032, U.S.A
| | - Esther SERRANO-SAIZ
- Departments of Pathology and Neurology, Taub Center for the Study of Alzheimer’s Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, 630 W. 168th Street, New York, NY 10032, U.S.A
| | - Nsikan AKPAN
- Departments of Pathology and Neurology, Taub Center for the Study of Alzheimer’s Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, 630 W. 168th Street, New York, NY 10032, U.S.A
| | - Carol M. TROY
- Departments of Pathology and Neurology, Taub Center for the Study of Alzheimer’s Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, 630 W. 168th Street, New York, NY 10032, U.S.A
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114
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Role of X11 and ubiquilin as in vivo regulators of the amyloid precursor protein in Drosophila. PLoS One 2008; 3:e2495. [PMID: 18575606 PMCID: PMC2429963 DOI: 10.1371/journal.pone.0002495] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Accepted: 05/05/2008] [Indexed: 01/29/2023] Open
Abstract
The Amyloid Precursor Protein (APP) undergoes sequential proteolytic cleavages through the action of β- and γ-secretase, which result in the generation of toxic β-amyloid (Aβ) peptides and a C-terminal fragment consisting of the intracellular domain of APP (AICD). Mutations leading to increased APP levels or alterations in APP cleavage cause familial Alzheimer's disease (AD). Thus, identification of factors that regulate APP steady state levels and/or APP cleavage by γ-secretase is likely to provide insight into AD pathogenesis. Here, using transgenic flies that act as reporters for endogenous γ-secretase activity and/or APP levels (GAMAREP), and for the APP intracellular domain (AICDREP), we identified mutations in X11L and ubiquilin (ubqn) as genetic modifiers of APP. Human homologs of both X11L (X11/Mint) and Ubqn (UBQLN1) have been implicated in AD pathogenesis. In contrast to previous reports, we show that overexpression of X11L or human X11 does not alter γ-secretase cleavage of APP or Notch, another γ-secretase substrate. Instead, expression of either X11L or human X11 regulates APP at the level of the AICD, and this activity requires the phosphotyrosine binding (PTB) domain of X11. In contrast, Ubqn regulates the levels of APP: loss of ubqn function leads to a decrease in the steady state levels of APP, while increased ubqn expression results in an increase in APP levels. Ubqn physically binds to APP, an interaction that depends on its ubiquitin-associated (UBA) domain, suggesting that direct physical interactions may underlie Ubqn-dependent regulation of APP. Together, our studies identify X11L and Ubqn as in vivo regulators of APP. Since increased expression of X11 attenuates Aβ production and/or secretion in APP transgenic mice, but does not act on γ-secretase directly, X11 may represent an attractive therapeutic target for AD.
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115
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Thromboxane receptor activation mediates isoprostane-induced increases in amyloid pathology in Tg2576 mice. J Neurosci 2008; 28:4785-94. [PMID: 18448655 DOI: 10.1523/jneurosci.0684-08.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Alzheimer's disease (AD) amyloid plaques are composed of amyloid-beta (Abeta) peptides produced from proteolytic cleavage of amyloid precursor protein (APP). Isoprostanes, markers of in vivo oxidative stress, are elevated in AD patients and in the Tg2576 mouse model of AD-like Abeta brain pathology. To determine whether isoprostanes increase Abeta production, we delivered isoprostane iPF(2alpha)-III into the brains of Tg2576 mice. Although treated mice showed increased brain Abeta levels and plaque-like deposits, this was blocked by a thromboxane (TP) receptor antagonist, suggesting that TP receptor activation mediates the effects of iPF(2alpha)-III on Abeta. This hypothesis was supported by cell culture studies that showed that TP receptor activation increased Abeta and secreted APP ectodomains. This increase was a result of increased APP mRNA stability leading to elevated APP mRNA and protein levels. The increased APP provides more substrate for alpha and beta secretase proteolytic cleavages, thereby increasing Abeta generation and amyloid plaque deposition. To test the effectiveness of targeting the TP receptor for AD therapy, Tg2576 mice underwent long-term treatment with S18886, an orally available TP receptor antagonist. S18886 treatment reduced amyloid plaques, insoluble Abeta, and APP levels, thereby implicating TP receptor signaling as a novel target for AD therapy.
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116
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Bogaerts V, Nuytemans K, Reumers J, Pals P, Engelborghs S, Pickut B, Corsmit E, Peeters K, Schymkowitz J, De Deyn PP, Cras P, Rousseau F, Theuns J, Van Broeckhoven C. Genetic variability in the mitochondrial serine proteaseHTRA2contributes to risk for Parkinson disease. Hum Mutat 2008; 29:832-40. [DOI: 10.1002/humu.20713] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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117
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Kumar-Singh S. Cerebral amyloid angiopathy: pathogenetic mechanisms and link to dense amyloid plaques. GENES BRAIN AND BEHAVIOR 2008; 7 Suppl 1:67-82. [PMID: 18184371 DOI: 10.1111/j.1601-183x.2007.00380.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cerebral amyloid angiopathy (CAA) of the amyloid-beta (Abeta) type is the most common form of sporadic CAA and is now also accepted as an early and integral part of Alzheimer's disease (AD) pathogenesis. Cerebral amyloid angiopathy is a risk factor for haemorrhagic stroke and is believed to independently contribute to dementia. Rare forms of hereditary cerebral amyloidosis caused by mutations within the Abeta domain of amyloid precursor protein (APP) have been identified, where mutant Abeta preferably deposits in vessels because of a decreased fibrillogenic potential and/or increased vasotopicity. A review of factors involved in CAA caused by wild-type Abeta suggests that increased Abeta levels in brain without an increased Abeta42/Abeta40 ratio is one of the most important prerequisites for vascular amyloidosis. This is exemplified by CAA observed in APP duplication and Down's syndrome patients, neprilysin polymorphism patients and knockout mice and Swedish APP (KM670/671NL) mice. Select presenilin mutations also lead to a prominent CAA, and importantly, presenilin mutations are shown to have varied effects on the production of Abeta40, the predominant amyloid found in CAA. Conversely, APP mutations such as Austrian APP (T714I) drastically decrease Abeta40 production and are deficient in CAA. Apolipoprotein E-epsilon4 is also shown to be a risk factor for CAA, and this might be because of its specific role in the aggregation of Abeta40. Recent data also suggest that dense-core senile plaques in humans and dense plaques in transgenic mice, composed predominantly of Abeta40, associate with vessels. This review highlights some of these aspects of genetics and biochemistry of CAA and pathological descriptions linked to a prominent CAA and/or dense plaques in humans and relevant mouse models and discusses how this knowledge has led to a better understanding of the processes involved in vascular amyloidosis, and in causing dementia, and thus has important therapeutic implications.
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Affiliation(s)
- S Kumar-Singh
- Neurodegenerative Brain Diseases Group, VIB Department of Molecular Genetics, University of Antwerp, Antwerpen, Belgium.
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118
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Liu Z, Jia J. The association of the regulatory region of the presenilin-2 gene with Alzheimer's disease in the Northern Han Chinese population. J Neurol Sci 2008; 264:38-42. [PMID: 17727891 DOI: 10.1016/j.jns.2007.06.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Revised: 06/24/2007] [Accepted: 06/28/2007] [Indexed: 11/22/2022]
Abstract
Presenilin-2 is one of the causative genes for familial Alzheimer's disease (FAD). Polymorphism of the promoter region of the presenilin-2 gene (PSEN2) has recently been reported in a Russian population to be associated with sporadic Alzheimer's disease (SAD). The purpose of this case-control study was to determine whether SAD is associated with the PSEN2 gene polymorphism in a Chinese population. We examined PSEN2 and APOE genotypes in 200 SAD patients and an equal number of age- and sex-matched controls from the same community, using the PCR-RFLP method. Allelic and genotypic distributions were performed using the Pearson Chi-square test for homogeneity. The interactions between variables were examined by logistic regression. The results revealed no significant differences in the frequency of the +A/-A polymorphism between AD and controls (chi(2)=3.857, p=0.145). However, in the subgroup of APOE epsilon4 non-carriers, there were significant differences in the distributions of both alleles (chi(2)=6.095, p=0.047) and genotypes (chi(2)=4.433, p=0.035) of the PSEN2 promoter in AD compared with controls. In APOE epsilon4 non-carrier group, with +A/+A as a reference, the -A/-A genotype was associated with a 4.657-fold increased risk for AD (chi(2)=5.783, p=0.016, OR=4.657, 95% CI=1.195-18.152). Using logistic analysis, there were no statistical interactions between PSEN2 and APOE genotypes, or between PSEN2 genotypes and age of onset. It is concluded that in the Northern Han Chinese population, the +A/-A polymorphism of the PSEN2 promoter is a moderate genetic risk factor for developing SAD, independent of the APOE epsilon4 allele.
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Affiliation(s)
- Zheng Liu
- Department of Neurology, Xuan Wu Hospital, Capital Medical University, Beijing 100053, China
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119
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Abstract
Alzheimer's disease (AD) is a complex disorder of the central nervous system (CNS). Molecular genetic research has provided a wealth of information regarding the genetic etiology of this devastating disease. Identification and functional characterization of autosomal dominant mutations in the amyloid precursor protein gene (APP) and the presenilin genes 1 and 2 (PSEN1 and PSEN2) have contributed substantially to our understanding of the biological mechanisms leading towards CNS neurodegeneration in AD. Nonetheless, a large part of the genetic etiology remains unresolved, especially that of more common, sporadic forms of AD. While substantial efforts were invested in the identification of genetic risk factors underlying sporadic AD, using carefully designed genetic association studies in large patient-control groups, the only firmly established risk factor remains the epsilon4 allele of the apolipoprotein E gene (APOE). Nevertheless, one can expect that with the current availability of high-throughput genotyping platforms and dense maps of single-nucleotide polymorphisms (SNPs), large-scale genetic studies will eventually generate additional knowledge about the genetic risk profile for AD. This review provides an overview of the current understanding in the field of AD genetics, covering both the rare monogenic forms as well as recent developments in the search for novel AD susceptibility genes.
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Affiliation(s)
- Nathalie Brouwers
- Neurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIB, Antwerpen, Belgium
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120
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Gacia M, Safranow K, Gabryelewicz T, Styczyńska M, Pepłońska B, Dziedziejko V, Jakubowska K, Chlubek D, Zekanowski C, Barcikowska M. Two polymorphisms of presenilin-2 gene (PSEN2) 5' regulatory region are not associated with Alzheimer's disease (AD) in the Polish population. J Neural Transm (Vienna) 2007; 115:85-90. [PMID: 18087668 DOI: 10.1007/s00702-007-0846-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 10/01/2007] [Indexed: 01/16/2023]
Abstract
Presenilin 2 gene (PSEN2) is one of the causative genes for familial Alzheimer's disease. A delA polymorphism located in PSEN2 promoter was proposed to be a risk factor for early-onset AD. We examined association between AD and PSEN2 polymorphisms located in two 5'UTR regions in group of 217 late-onset AD patients, 109 mild cognitive impairment patients, and 225 non-demented control subjects. No significant differences for genotype and allele distributions of a delA and a novel insAC polymorphisms in the studied groups as compared to controls were observed. Univariate and multivariate risk estimation shows that neither delA, insAC alleles nor the genotypes are risk factors for AD. No significant interaction between the APOE4 and PSEN2 polymorphisms was found. A bioinformatic analysis showed that delA polymorphism influences binding sites of transcription factors involved in the cellular processes related to AD. The rare variants identified in exon 3 of the PSEN2 could have a potential influence on PSEN2 transcript splicing.
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Affiliation(s)
- M Gacia
- Medical Research Center, Department of Neurodegenerative Disorders, Polish Academy of Sciences, Warszawa, Poland
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121
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Venezia V, Nizzari M, Carlo P, Corsaro A, Florio T, Russo C. Amyloid precursor protein and presenilin involvement in cell signaling. NEURODEGENER DIS 2007; 4:101-11. [PMID: 17596704 DOI: 10.1159/000101834] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
To date the most relevant role for the amyloid precursor protein (APP) and for the presenilins (PSs) on Alzheimer's disease (AD) genesis is linked to the 'amyloid hypothesis', which considers an aberrant formation of amyloid-beta peptides the cause of neurodegeneration. In this view, APP is merely a substrate, cleaved by the gamma-secretase complex to form toxic amyloid peptides, PSs are key players in gamma-secretase complex, and corollary or secondary events are Tau-linked pathology and gliosis. A second theory, complementary to the amyloid hypothesis, proposes that APP and PSs may modulate a yet unclear cell signal, the disruption of which may induce cell-cycle abnormalities, neuronal death, eventually amyloid formation and finally dementia. This hypothesis is supported by the presence of a complex network of proteins, with a clear relevance for signal transduction mechanisms, which interact with APP or PSs. In this scenario, the C-terminal domain of APP has a pivotal role due to the presence of the 682YENPTY687 motif that represents the docking site for multiple interacting proteins involved in cell signaling. In this review we discuss the significance of novel findings related to cell signaling events modulated by APP and PSs for AD development.
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Affiliation(s)
- Valentina Venezia
- Department of Oncology, Biology and Genetics, University of Genova, Genova, Italy
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122
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Moldrich RX. A yeast model of Down syndrome. Int J Dev Neurosci 2007; 25:539-43. [DOI: 10.1016/j.ijdevneu.2007.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 10/02/2007] [Accepted: 10/03/2007] [Indexed: 10/22/2022] Open
Affiliation(s)
- Randal X. Moldrich
- The Queensland Brain InstituteThe University of QueenslandSt. LuciaQueensland4072Australia
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123
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Lambert JC, Amouyel P. Genetic heterogeneity of Alzheimer's disease: complexity and advances. Psychoneuroendocrinology 2007; 32 Suppl 1:S62-70. [PMID: 17659844 DOI: 10.1016/j.psyneuen.2007.05.015] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 04/27/2007] [Accepted: 05/02/2007] [Indexed: 11/25/2022]
Abstract
Most of what we know about the pathological process of Alzheimer's disease (AD) results from research on the amyloid cascade hypothesis. This hypothesis in turn is derived largely from the characterization of rare disease-causing mutations in three genes, which code for the amyloid precursor protein (APP), presenilin 1 (PS-1) and presenilin 2 (PS-2) and account for most cases of early-onset autosomal dominant familial AD. These genetic findings also suggested that better understanding of the genetic components of AD, even in the late-onset sporadic forms of the disease, might help to identify central pathways of the AD process and lead to the rapid development of active molecules. Twin studies have reinforced the rationale of this approach, for they indicate that more than 50% of the late-onset AD risk may be attributable to genetic factors. The 1993 discovery that the apolipoprotein E4 (ApoE4) allele is genetically associated with increased risk in both sporadic and familial late-onset Alzheimer's disease strongly supports the validity of this genetic approach. Further progress based on this major finding has nonetheless been disappointing and raises questions about it. First, despite intensive researches, the exact role of APOE in the pathophysiological process still remains unknown. Second, the APOE gene is the only gene so far recognized as a consistent genetic determinant of sporadic forms of AD, even though numerous studies have looked for such genes; these disappointing results suggest persistent methodological limitations. However, recent methodologies allowing new strategies may allow important breakthrough.
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Affiliation(s)
- Jean-Charles Lambert
- Institut Pasteur de Lille, INSERM U744, Université de Lille II, 1, Rue du Professeur Calmette, 59019 Lille Cédex, France.
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124
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Van Broeck B, Van Broeckhoven C, Kumar-Singh S. Current insights into molecular mechanisms of Alzheimer disease and their implications for therapeutic approaches. NEURODEGENER DIS 2007; 4:349-65. [PMID: 17622778 DOI: 10.1159/000105156] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Accepted: 12/12/2006] [Indexed: 01/13/2023] Open
Abstract
During the last 10 years, a lot of progress has been made in unraveling the pathogenic cascade leading to Alzheimer disease (AD). According to the most widely accepted hypothesis, production and aggregation of the amyloid beta (Abeta) peptide plays a key role in AD, and thus therapeutic interference with these processes is the subject of intense research. However, some important aspects of the disease mechanism are not yet fully understood. There is no consensus as yet on whether the disease acts through a loss- (LOF) or a gain-of-function (GOF) mechanism. While for many years, an increased production of Abeta42 was considered to be the prime culprit for the initiation of the disease process, and accordingly Abeta42 is elevated by AD-related presenilin(PS) mutations, recent data strongly suggest that PS mutations also lead to a LOF of PS towards a plethora of its substrates including amyloid precursor protein. How this PS LOF, especially decreased Abeta40 secretion due to mutant PS, impacts on the disease pathogenesis is yet to be elucidated. Secondly, vascular abnormalities--frequently observed to co-occur with AD--might also play a critical role in the initiation and aggravation of AD pathology given that the elimination of Abeta through a vascular route is an important brain Abeta clearance mechanism and its failure leads to formation of vascular amyloidosis and dense-core plaques. In this review, we will first focus on the important issue of a LOF versus a GOF mechanism for AD due to mutant PS, as well as on the possible role of vascular damage and reduced perfusion in AD. Special emphasis will be given to some of the AD mouse models that have helped to gain insights into the disease mechanism. Secondly, considering these mechanistic insights, we will discuss some therapeutic strategies which are currently in clinical or preclinical trials for AD.
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Affiliation(s)
- Bianca Van Broeck
- Neurodegenerative Brain Diseases Group, Department of Molecular Genetics, VIB, University of Antwerp, Universiteitsplein I, BE-2610 Antwerp, Belgium
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125
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Matsui T, Ingelsson M, Fukumoto H, Ramasamy K, Kowa H, Frosch MP, Irizarry MC, Hyman BT. Expression of APP pathway mRNAs and proteins in Alzheimer's disease. Brain Res 2007; 1161:116-23. [PMID: 17586478 DOI: 10.1016/j.brainres.2007.05.050] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 05/29/2007] [Accepted: 05/31/2007] [Indexed: 12/17/2022]
Abstract
In both trisomy 21 and rare cases of triplication of amyloid precursor protein (APP) Alzheimer's disease (AD) pathological changes are believed to be secondary to increased expression of APP. We hypothesized that sporadic AD may also be associated with changes in transcription of APP or its metabolic partners. To address this issue, temporal neocortex of 27 AD and 21 non-demented control brains was examined to assess mRNA levels of APP isoforms (total APP, APP containing the Kunitz protease inhibitor domain [APP-KPI] and APP770) and APP metabolic enzymatic partners (the APP cleaving enzymes beta-secretase [BACE] and presenilin-1 [PS-1], and putative clearance molecules, low-density lipoprotein receptor protein [LRP] and apolipoprotein E [apoE]). Furthermore, we evaluated how changes in APP at the mRNA level affect the amount of Tris buffer extractable APP protein and Abeta40 and 42 peptides in AD and control brains. As assessed by quantitative PCR, APP-KPI (p=0.007), APP770 (p=0.004), PS-1 (p=0.004), LRP (p=0.003), apoE (p=0.0002) and GFAP (p<0.0001) mRNA levels all increased in AD, and there was a shift from APP695 (a neuronal isoform) towards KPI containing isoforms that are present in glia as well. APP-KPI mRNA levels correlated with soluble APPalpha-KPI protein (sAPPalpha-KPI) levels measured by ELISA (tau=0.33, p=0.015 by Kendall's rank correlation); in turn, soluble APPalpha-KPI protein levels positively correlated with Tris-extractable, soluble Abeta40 (p=0.046) and 42 levels (p=0.007). The ratio of soluble APPalpha-KPI protein levels to total APP protein increased in AD, and also correlated with GFAP protein levels in AD. These results suggest that altered transcription of APP in AD is proportionately associated with Abeta peptide, may occur in the context of gliosis, and may contribute to Abeta deposition in sporadic AD.
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Affiliation(s)
- Toshifumi Matsui
- Alzheimer Disease Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Charlestown, MA 02129, USA
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126
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Nowotny P, Simcock X, Bertelsen S, Hinrichs AL, Kauwe JSK, Mayo K, Smemo S, Morris JC, Goate A. Association studies testing for risk for late-onset Alzheimer's disease with common variants in the beta-amyloid precursor protein (APP). Am J Med Genet B Neuropsychiatr Genet 2007; 144B:469-74. [PMID: 17427190 DOI: 10.1002/ajmg.b.30485] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Linkage studies have suggested a susceptibility locus for late-onset Alzheimer's disease (LOAD) on chromosome 21. A functional candidate gene in this region is the beta-amyloid precursor protein (APP) gene. Previously, coding mutations in APP have been associated with early onset Alzheimer's Disease (EOAD). Three copies of APP are associated with AD pathology in Down's syndrome and in EOAD, suggesting that overexpression of APP may be a risk factor for LOAD. Although APP is a strong functional and positional candidate, to date there has been no thorough investigation using a dense map of SNPs across the APP gene. In order to investigate the role of common variation in the APP gene in the risk of LOAD, we genotyped 44 SNPs, spanning 300 kb spanning the entire gene, in a large case-control series of 738 AD cases and 657 healthy controls. The SNPs showed no association in genotypic or allelic tests, even after stratification for presence or absence of the APOE 4 allele. Haplotype analysis also failed to reveal significant association with any common haplotypes. These results suggest that common variation in the APP gene is not a significant risk factor for LOAD. However, we cannot rule out the possibility that multiple rare variants that increase APP expression or Abeta production might influence the risk for LOAD.
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Affiliation(s)
- Petra Nowotny
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA
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127
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128
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Gamerdinger M, Clement AB, Behl C. Cholesterol-like effects of selective cyclooxygenase inhibitors and fibrates on cellular membranes and amyloid-beta production. Mol Pharmacol 2007; 72:141-51. [PMID: 17395689 DOI: 10.1124/mol.107.034009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Strong evidence suggests a mechanistic link between cholesterol metabolism and the formation of amyloid-beta peptides, the principal constituents of senile plaques found in the brains of patients with Alzheimer's disease. Here, we show that several fibrates and diaryl heterocycle cyclooxygenase inhibitors, among them the commonly used drugs fenofibrate and celecoxib, exhibit effects similar to those of cholesterol on cellular membranes and amyloid precursor protein (APP) processing. These drugs have the same effects on membrane rigidity as cholesterol, monitored here by an increase in fluorescence anisotropy. The effect of the drugs on cellular membranes was also reflected in the inhibitory action on the sarco(endo)plasmic reticulum Ca(2+)-ATPase, which is known to be inhibited by excess ordering of membrane lipids. The drug-induced decrease of membrane fluidity correlated with an increased association of APP and its beta-site cleaving enzyme BACE1 with detergent-resistant membranes (DRMs), which represent membrane clusters of substantial rigidity. DRMs are hypothesized to serve as platforms for the amyloidogenic processing of APP. According to this hypothesis, both cholesterol and the examined compounds stimulated the beta-secretase cleavage of APP, resulting in a massive increase of secreted amyloid-beta peptides. The membrane-ordering potential of the drugs was observed in a cell-free assay, suggesting that the amyloid-beta promoting effect was analog to cholesterol due to primary effect on membrane rigidity. Because fenofibrate and celecoxib are widely used in humans as hypolipidemic drugs for prevention of atherosclerosis and as anti-inflammatory drugs against arthritis, possible side effects should be considered upon long-term clinical application.
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Affiliation(s)
- Martin Gamerdinger
- Department of Pathobiochemistry, Medical School, Johannes Gutenberg University, Mainz, Germany
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129
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Copanaki E, Schürmann T, Eckert A, Leuner K, Müller WE, Prehn JHM, Kögel D. The amyloid precursor protein potentiates CHOP induction and cell death in response to ER Ca2+ depletion. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:157-65. [PMID: 17113167 DOI: 10.1016/j.bbamcr.2006.10.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 09/20/2006] [Accepted: 10/10/2006] [Indexed: 11/17/2022]
Abstract
Here we investigated the role of the amyloid precursor protein (APP) in regulation of Ca(2+) store depletion-induced neural cell death. Ca(2+) store depletion from the endoplasmic reticulum (ER) was induced by the SERCA (Sarco/Endoplasmic Reticulum Calcium ATPase) inhibitor thapsigargin which led to a rapid induction of the unfolded protein response (UPR) and a delayed activation of executioner caspases in the cultures. Overexpression of APP potently enhanced cytosolic Ca(2+) levels and cell death after ER Ca(2+) store depletion in comparison to vector-transfected controls. GeneChip and RT-PCR analysis revealed that the expression of classical UPR chaperone genes was not altered by overexpression of APP. Interestingly, the induction of the ER stress-responsive pro-apoptotic transcription factor CHOP was significantly upregulated in APP-overexpressing cells in comparison to vector-transfected controls. Chelation of intracellular Ca(2+) with BAPTA-AM revealed that enhanced CHOP expression after store depletion occurred in a Ca(2+)-dependent manner in APP-overexpressing cells. Prevention of CHOP induction by BAPTA-AM and by RNA interference was also able to abrogate the potentiating effect of APP on thapsigargin-induced apoptosis. Application of the store-operated channel (SOC)-inhibitors SK & F96365 and 2-APB downmodulated APP-triggered potentiation of cytosolic Ca(2+) levels and apoptosis after treatment with thapsigargin. Our data demonstrate that APP significantly modulates Ca(2+) store depletion-induced cell death in a SOC- and CHOP-dependent manner, but independent of the UPR.
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Affiliation(s)
- Ekaterini Copanaki
- Department of Neurosurgery, Johann Wolfgang Goethe University Clinics, D-60590 Frankfurt, Germany
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130
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Boeras DI, Granic A, Padmanabhan J, Crespo NC, Rojiani AM, Potter H. Alzheimer's presenilin 1 causes chromosome missegregation and aneuploidy. Neurobiol Aging 2006; 29:319-28. [PMID: 17169464 PMCID: PMC2692942 DOI: 10.1016/j.neurobiolaging.2006.10.027] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 09/27/2006] [Accepted: 10/25/2006] [Indexed: 11/24/2022]
Abstract
Mutations in the presenilin 1 gene cause most early onset familial Alzheimer's disease (FAD). Here, we report that a defect in the cell cycle - improper chromosome segregation - can be caused by abnormal presenilin function and therefore may contribute to AD pathogenesis. Specifically we find that either over-expression or FAD mutation in presenilin 1 (M146L and M146V) leads to chromosome missegregation and aneuploidy in vivo and in vitro: (1) Up to 20% of lymphocytes and neurons of FAD-PS-1 transgenic and knocking mice are aneuploid by metaphase chromosome analysis and in situ hybridization. (2) Transiently transfected human cells over-expressing normal or mutant PS-1 develop similar aneuploidy within 48 h, including trisomy 21. (3) Mitotic spindles in the PS-1 transfected cells contain abnormal microtubule arrays and lagging chromosomes. Several mechanisms by which chromosome missegregation induced by presenilin may contribute to Alzheimer's disease are discussed.
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Affiliation(s)
- Debrah I. Boeras
- Johnnie B. Byrd Sr. Alzheimer’s Center and Research Institute, Tampa, FL 33647, USA
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
| | - Antoneta Granic
- Johnnie B. Byrd Sr. Alzheimer’s Center and Research Institute, Tampa, FL 33647, USA
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
| | - Jaya Padmanabhan
- Johnnie B. Byrd Sr. Alzheimer’s Center and Research Institute, Tampa, FL 33647, USA
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
| | - Nichole C. Crespo
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
| | - Amyn M. Rojiani
- Department of Pathology, University of South Florida College of Medicine, Tampa, FL 33612, USA
| | - Huntington Potter
- Johnnie B. Byrd Sr. Alzheimer’s Center and Research Institute, Tampa, FL 33647, USA
- Department of Molecular Medicine and Suncoast Gerontology Center, University of South Florida, College of Medicine, Tampa, FL 33612, USA
- H. Lee Moffitt Cancer Center, Tampa, FL 33612, USA
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131
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Lv H, Jia L, Jia J. Promoter polymorphisms which modulate APP expression may increase susceptibility to Alzheimer's disease. Neurobiol Aging 2006; 29:194-202. [PMID: 17112637 DOI: 10.1016/j.neurobiolaging.2006.10.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 09/17/2006] [Accepted: 10/02/2006] [Indexed: 10/23/2022]
Abstract
Increasing evidence indicates that variants in promoter of the beta-amyloid precursor protein (APP) gene could up-regulate the APP gene expression and aggravate the amyloid beta protein (A beta) accumulation, thus contributing to the development of Alzheimer's disease (AD). In Chinese Han populations we found three polymorphisms in APP promoter: -877T/C(rs466433), -955A/G(rs364048) and -9G/C. The -877T and -955A alleles were over-represented in 209 sporadic AD (SAD) patients when compared to those in 437 healthy individuals. Furthermore, -877T/C and -955A/G were in strong linkage disequilibrium and they constructed a relatively risky -877T/-955A and a relatively protective -877C/-955G. Luciferase reporter assay indicated -877T/-955A had four times higher transcriptional activity than -877C/-955G. A more marked increase in -877T/-955A transcriptional activity was seen when under A beta(25-35) treatment. As for the -9G/C polymorphism, significant differences between the two alleles were not observed either in genetic evaluation or in functional assay. The present study provides strong evidence that APP promoter polymorphisms that significantly increase APP expression levels are associated with development of SAD.
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Affiliation(s)
- Haiyan Lv
- Department of Neurology, Xuanwu Hospital of the Capital University of Medical Sciences, Beijing 100053, PR China
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132
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Lee JA, Lupski JR. Genomic rearrangements and gene copy-number alterations as a cause of nervous system disorders. Neuron 2006; 52:103-21. [PMID: 17015230 DOI: 10.1016/j.neuron.2006.09.027] [Citation(s) in RCA: 199] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Genomic disorders are a group of human genetic diseases caused by genomic rearrangements resulting in copy-number variation (CNV) affecting a dosage-sensitive gene or genes critical for normal development or maintenance. These disorders represent a wide range of clinically distinct entities but include many diseases affecting nervous system function. Herein, we review selected neurodevelopmental, neurodegenerative, and psychiatric disorders either known or suggested to be caused by genomic rearrangement and CNV. Further, we emphasize the cause-and-effect relationship between gene CNV and complex disease traits. We also discuss the prevalence and heritability of CNV, the correlation between CNV and higher-order genome architecture, and the heritability of personality, behavioral, and psychiatric traits. We speculate that CNV could underlie a significant proportion of normal human variation including differences in cognitive, behavioral, and psychological features.
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Affiliation(s)
- Jennifer A Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
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133
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Majercak J, Ray WJ, Espeseth A, Simon A, Shi XP, Wolffe C, Getty K, Marine S, Stec E, Ferrer M, Strulovici B, Bartz S, Gates A, Xu M, Huang Q, Ma L, Shughrue P, Burchard J, Colussi D, Pietrak B, Kahana J, Beher D, Rosahl T, Shearman M, Hazuda D, Sachs AB, Koblan KS, Seabrook GR, Stone DJ. LRRTM3 promotes processing of amyloid-precursor protein by BACE1 and is a positional candidate gene for late-onset Alzheimer's disease. Proc Natl Acad Sci U S A 2006; 103:17967-72. [PMID: 17098871 PMCID: PMC1635650 DOI: 10.1073/pnas.0605461103] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rare familial forms of Alzheimer's disease (AD) are thought to be caused by elevated proteolytic production of the Abeta42 peptide from the beta-amyloid-precursor protein (APP). Although the pathogenesis of the more common late-onset AD (LOAD) is not understood, BACE1, the protease that cleaves APP to generate the N terminus of Abeta42, is more active in patients with LOAD, suggesting that increased amyloid production processing might also contribute to the sporadic disease. Using high-throughput siRNA screening technology, we assessed 15,200 genes for their role in Abeta42 secretion and identified leucine-rich repeat transmembrane 3 (LRRTM3) as a neuronal gene that promotes APP processing by BACE1. siRNAs targeting LRRTM3 inhibit the secretion of Abeta40, Abeta42, and sAPPbeta, the N-terminal APP fragment produced by BACE1 cleavage, from cultured cells and primary neurons by up to 60%, whereas overexpression increases Abeta secretion. LRRTM3 is expressed nearly exclusively in the nervous system, including regions affected during AD, such as the dentate gyrus. Furthermore, LRRTM3 maps to a region of chromosome 10 linked to both LOAD and elevated plasma Abeta42, and is structurally similar to a family of neuronal receptors that includes the NOGO receptor, an inhibitor of neuronal regeneration and APP processing. Thus, LRRTM3 is a functional and positional candidate gene for AD, and, given its receptor-like structure and restricted expression, a potential therapeutic target.
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Affiliation(s)
| | | | | | | | | | | | | | - Shane Marine
- Automated Biotechnology, Merck & Co., Inc., West Point, PA 19486
| | - Erica Stec
- Automated Biotechnology, Merck & Co., Inc., West Point, PA 19486
| | - Marc Ferrer
- Automated Biotechnology, Merck & Co., Inc., West Point, PA 19486
| | - Berta Strulovici
- Automated Biotechnology, Merck & Co., Inc., West Point, PA 19486
| | | | | | - Min Xu
- Molecular and Cellular Technology, and
| | | | - Lei Ma
- Department of *Alzheimer's Research
| | | | | | | | | | | | - Dirk Beher
- Department of Alzheimer's Research, Merck Research Laboratories, Boston, MA 02115
| | - Thomas Rosahl
- Department of Alzheimer's Research, Merck Research Laboratories, Boston, MA 02115
| | - Mark Shearman
- Department of Alzheimer's Research, Merck Research Laboratories, Boston, MA 02115
| | | | - Alan B. Sachs
- Molecular Profiling, Rosetta Inpharmatics LLC, Seattle, WA 98109; and
| | | | | | - David J. Stone
- Molecular Profiling, Rosetta Inpharmatics LLC, Seattle, WA 98109; and
- **To whom correspondence should be addressed at:
Merck & Co., Inc., 770 Sumneytown Pike, West Point, PA 19486. E-mail:
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Antonarakis SE, Epstein CJ. The challenge of Down syndrome. Trends Mol Med 2006; 12:473-9. [PMID: 16935027 DOI: 10.1016/j.molmed.2006.08.005] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Revised: 07/21/2006] [Accepted: 08/14/2006] [Indexed: 01/01/2023]
Abstract
Down syndrome (DS) has been recognized as a clinical entity for about 150 years, but it is only recently that there has been hope for the possibility to understand its pathogenesis and to use this information to devise approaches for the prevention and treatment of its numerous features. The earlier pessimism was due to several reasons, including: (i) the nature of the genetic defect that leads to the syndrome; (ii) the multiplicity of systems involved; and (iii) the high degree of variability of the phenotype. However, science has now caught up with the problem, and recent developments, especially in genetics, genomics, developmental biology and neuroscience, suggest that these potential impediments might not be as arduous as once appeared. As a result, basic research on DS is now rapidly accelerating, and there is hope that the findings will be translatable into benefit for people with DS.
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Affiliation(s)
- Stylianos E Antonarakis
- Department of Genetic Medicine and Development, University of Geneva Medical School, University Hospitals of Geneva, 1 rue Michel-Servet, 1211 Geneva, Switzerland
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Dillen K, Annaert W. A Two Decade Contribution of Molecular Cell Biology to the Centennial of Alzheimer's Disease: Are We Progressing Toward Therapy? INTERNATIONAL REVIEW OF CYTOLOGY 2006; 254:215-300. [PMID: 17148000 DOI: 10.1016/s0074-7696(06)54005-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Alzheimer's disease (AD), described for the first time 100 years ago, is a neurodegenerative disease characterized by two neuropathological hallmarks: neurofibrillary tangles containing hyperphosphorylated tau and senile plaques. These lesions are likely initiated by an imbalance between production and clearance of amyloid beta, leading to increased oligomerization of these peptides, formation of amyloid plaques in the brain of the patient, and final dementia. Amyloid beta is generated from amyloid precursor protein (APP) by subsequent beta- and gamma-secretase cleavage, the latter being a multiprotein complex consisting of presenilin-1 or -2, nicastrin, APH-1, and PEN-2. Alternatively, APP can be cleaved by alpha- and gamma-secretase, precluding the production of Abeta. In this review, we discuss the major breakthroughs during the past two decades of molecular cell biology and the current genetic and cell biological state of the art on APP proteolysis, including structure-function relationships and subcellular localization. Finally, potential directions for cell biological research toward the development of AD therapies are briefly discussed.
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Affiliation(s)
- Katleen Dillen
- Laboratory for Membrane Trafficking, Center for Human Genetics/VIB1104 & KULeuven, Gasthuisberg O&N1, B-3000 Leuven, Belgium
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