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Orlowski A, Karippaparambil J, Paumier JM, Ghanta S, Pallares E, Tandukar J, Gao R, Gowrishankar S. Axonal organelle buildup from loss of AP-4 complex function causes exacerbation of amyloid plaque pathology and gliosis in Alzheimer's disease mouse model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.31.587499. [PMID: 38617351 PMCID: PMC11014495 DOI: 10.1101/2024.03.31.587499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Lysosomes and related precursor organelles robustly build up in swollen axons that surround amyloid plaques and disrupted axonal lysosome transport has been implicated in worsening Alzheimer's pathology. Our prior studies have revealed that loss of Adaptor protein-4 (AP-4) complex function, linked primarily to Spastic Paraplegia (HSP), leads to a similar build of lysosomes in structures we term "AP-4 dystrophies". Surprisingly, these AP-4 dystrophies were also characterized by enrichment of components of APP processing machinery, β-site cleaving enzyme 1 (BACE1) and Presenilin 2. Our studies examining whether the abnormal axonal lysosome build up resulting from AP-4 loss could lead to amyloidogenesis revealed that the loss of AP-4 complex function in an Alzheimer's disease model resulted in a strong increase in size and abundance of amyloid plaques in the hippocampus and corpus callosum as well as increased microglial association with the plaques. Interestingly, we found a further increase in enrichment of the secretase, BACE1, in the axonal swellings of the plaques of Alzheimer model mice lacking AP-4 complex compared to those having normal AP-4 complex function, suggestive of increased amyloidogenic processing under this condition. Additionally, the exacerbation of plaque pathology was region-specific as it did not increase in the cortex. The burden of the AP-4 linked axonal dystrophies/AP-4 dystrophies was higher in the corpus callosum and hippocampus compared to the cortex, establishing the critical role of AP-4 -dependent axonal lysosome transport and maturation in regulating amyloidogenic amyloid precursor protein processing.
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Affiliation(s)
- Alex Orlowski
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois Chicago, Chicago, IL 60612 USA
| | - Joseph Karippaparambil
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois Chicago, Chicago, IL 60612 USA
| | - Jean-Michel Paumier
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois Chicago, Chicago, IL 60612 USA
| | - Shraddha Ghanta
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois Chicago, Chicago, IL 60612 USA
| | - Eduardo Pallares
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois Chicago, Chicago, IL 60612 USA
| | - Jamuna Tandukar
- Department of Biological Sciences, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL 60607 USA
| | - Ruixuan Gao
- Department of Biological Sciences, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL 60607 USA
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL 60607 USA
| | - Swetha Gowrishankar
- Department of Anatomy and Cell Biology, College of Medicine, University of Illinois Chicago, Chicago, IL 60612 USA
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Cadiz MP, Gibson KA, Todd KT, Nascari DG, Massa N, Lilley MT, Olney KC, Al-Amin MM, Jiang H, Holtzman DM, Fryer JD. Aducanumab anti-amyloid immunotherapy induces sustained microglial and immune alterations. J Exp Med 2024; 221:e20231363. [PMID: 38226975 PMCID: PMC10791560 DOI: 10.1084/jem.20231363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 11/01/2023] [Accepted: 12/14/2023] [Indexed: 01/17/2024] Open
Abstract
Aducanumab, an anti-amyloid immunotherapy for Alzheimer's disease, efficiently reduces Aβ, though its plaque clearance mechanisms, long-term effects, and effects of discontinuation are not fully understood. We assessed the effect of aducanumab treatment and withdrawal on Aβ, neuritic dystrophy, astrocytes, and microglia in the APP/PS1 amyloid mouse model. We found that reductions in amyloid and neuritic dystrophy during acute treatment were accompanied by microglial and astrocytic activation, and microglial recruitment to plaques and adoption of an aducanumab-specific pro-phagocytic and pro-degradation transcriptomic signature, indicating a role for microglia in aducanumab-mediated Aβ clearance. Reductions in Aβ and dystrophy were sustained 15 but not 30 wk after discontinuation, and reaccumulation of plaques coincided with loss of the microglial aducanumab signature and failure of microglia to reactivate. This suggests that despite the initial benefit from treatment, microglia are unable to respond later to restrain plaque reaccumulation, making further studies on the effect of amyloid-directed immunotherapy withdrawal crucial for assessing long-term safety and efficacy.
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Affiliation(s)
- Mika P. Cadiz
- Department of Neuroscience, Mayo Clinic, Scottsdale, AZ, USA
- Neuroscience Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Scottsdale, AZ, USA
| | | | - Kennedi T. Todd
- Department of Neuroscience, Mayo Clinic, Scottsdale, AZ, USA
| | - David G. Nascari
- Department of Neuroscience, Mayo Clinic, Scottsdale, AZ, USA
- Biochemistry and Molecular Biology Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Scottsdale, AZ, USA
- MD/PhD Training Program, Mayo Clinic, Scottsdale, AZ, USA
| | - Nashali Massa
- Department of Neuroscience, Mayo Clinic, Scottsdale, AZ, USA
- Neuroscience Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Scottsdale, AZ, USA
| | - Meredith T. Lilley
- Neuroscience Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Scottsdale, AZ, USA
| | | | - Md Mamun Al-Amin
- Department of Medical and Molecular Genetics, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Hong Jiang
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA
| | - David M. Holtzman
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer’s Disease Research Center, Washington University School of Medicine, St. Louis, MO, USA
| | - John D. Fryer
- Department of Neuroscience, Mayo Clinic, Scottsdale, AZ, USA
- Neuroscience Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Scottsdale, AZ, USA
- Biochemistry and Molecular Biology Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Scottsdale, AZ, USA
- MD/PhD Training Program, Mayo Clinic, Scottsdale, AZ, USA
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3
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Jang J, Yeo S, Baek S, Jung HJ, Lee MS, Choi SH, Choe Y. Abnormal accumulation of extracellular vesicles in hippocampal dystrophic axons and regulation by the primary cilia in Alzheimer's disease. Acta Neuropathol Commun 2023; 11:142. [PMID: 37667395 PMCID: PMC10478284 DOI: 10.1186/s40478-023-01637-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 08/15/2023] [Indexed: 09/06/2023] Open
Abstract
Dystrophic neurites (DNs) are abnormal axons and dendrites that are swollen or deformed in various neuropathological conditions. In Alzheimer's disease (AD), DNs play a crucial role in impairing neuronal communication and function, and they may also contribute to the accumulation and spread of amyloid beta (Aβ) in the brain of AD patients. However, it is still a challenge to understand the DNs of specific neurons that are vulnerable to Aβ in the pathogenesis of AD. To shed light on the development of radiating DNs, we examined enriched dystrophic hippocampal axons in a mouse model of AD using a three-dimensional rendering of projecting neurons. We employed the anterograde spread of adeno-associated virus (AAV)1 and conducted proteomic analysis of synaptic compartments obtained from hippocampo-septal regions. Our findings revealed that DNs were formed due to synaptic loss at the axon terminals caused by the accumulation of extracellular vesicle (EV). Abnormal EV-mediated transport and exocytosis were identified in association with primary cilia, indicating their involvement in the accumulation of EVs at presynaptic terminals. To further address the regulation of DNs by primary cilia, we conducted knockdown of the Ift88 gene in hippocampal neurons, which impaired EV-mediated secretion of Aβ and promoted accumulation of axonal spheroids. Using single-cell RNA sequencing, we identified the septal projecting hippocampal somatostatin neurons (SOM) as selectively vulnerable to Aβ with primary cilia dysfunction and vesicle accumulation. Our study suggests that DNs in AD are initiated by the ectopic accumulation of EVs at the neuronal axon terminals, which is affected by neuronal primary cilia.
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Affiliation(s)
| | - Seungeun Yeo
- Korea Brain Research Institute, Daegu, 41068, Korea
| | | | | | - Mi Suk Lee
- Korea Brain Research Institute, Daegu, 41068, Korea
| | | | - Youngshik Choe
- Korea Brain Research Institute, Daegu, 41068, Korea.
- , Daegu, Korea.
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4
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Pontrello CG, McWhirt JM, Glabe CG, Brewer GJ. Age-Related Oxidative Redox and Metabolic Changes Precede Intraneuronal Amyloid-β Accumulation and Plaque Deposition in a Transgenic Alzheimer's Disease Mouse Model. J Alzheimers Dis 2022; 90:1501-1521. [PMID: 36278355 PMCID: PMC9789488 DOI: 10.3233/jad-220824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Many identified mechanisms could be upstream of the prominent amyloid-β (Aβ) plaques in Alzheimer's disease (AD). OBJECTIVE To profile the progression of pathology in AD. METHODS We monitored metabolic signaling, redox stress, intraneuronal amyloid-β (iAβ) accumulation, and extracellular plaque deposition in the brains of 3xTg-AD mice across the lifespan. RESULTS Intracellular accumulation of aggregated Aβ in the CA1 pyramidal cells at 9 months preceded extracellular plaques that first presented in the CA1 at 16 months of age. In biochemical assays, brain glutathione (GSH) declined with age in both 3xTg-AD and non-transgenic controls, but the decline was accelerated in 3xTg-AD brains from 2 to 4 months. The decline in GSH correlated exponentially with the rise in iAβ. Integrated metabolic signaling as the ratio of phospho-Akt (pAkt) to total Akt (tAkt) in the PI3kinase and mTOR pathway declined at 6, 9, and 12 months, before rising at 16 and 20 months. These pAkt/tAkt ratios correlated with both iAβ and GSH levels in a U-shaped relationship. Selective vulnerability of age-related AD-genotype-specific pAkt changes was greatest in the CA1 pyramidal cell layer. To demonstrate redox causation, iAβ accumulation was lowered in cultured middle-age adult 3xTg-AD neurons by treatment of the oxidized redox state in the neurons with exogenous cysteine. CONCLUSION The order of pathologic progression in the 3xTg-AD mouse was loss of GSH (oxidative redox shift) followed by a pAkt/tAkt metabolic shift in CA1, iAβ accumulation in CA1, and extracellular Aβ deposition. Upstream targets may prove strategically more effective for therapy before irreversible changes.
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Affiliation(s)
- Crystal G. Pontrello
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA, USA,
Department of Biomedical Engineering, University of California Irvine, Irvine, CA, USA
| | - Joshua M. McWhirt
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA, USA
| | - Charles G. Glabe
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA, USA,
Center for Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA, USA,
MIND Institute, University of California Irvine, Irvine, CA, USA
| | - Gregory J. Brewer
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA, USA,
Center for Neurobiology of Learning and Memory, University of California Irvine, Irvine, CA, USA,
MIND Institute, University of California Irvine, Irvine, CA, USA,Correspondence to: Gregory J. Brewer, Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA. Tel.: +1 217 502 4511; E-mail:
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5
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Jordà‐Siquier T, Petrel M, Kouskoff V, Smailovic U, Cordelières F, Frykman S, Müller U, Mulle C, Barthet G. APP accumulates with presynaptic proteins around amyloid plaques: A role for presynaptic mechanisms in Alzheimer's disease? Alzheimers Dement 2022; 18:2099-2116. [PMID: 35076178 PMCID: PMC9786597 DOI: 10.1002/alz.12546] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 09/21/2021] [Accepted: 10/25/2021] [Indexed: 01/31/2023]
Abstract
In Alzheimer's disease (AD), the distribution of the amyloid precursor protein (APP) and its fragments other than amyloid beta, has not been fully characterized. Here, we investigate the distribution of APP and its fragments in human AD brain samples and in mouse models of AD in reference to its proteases, synaptic proteins, and histopathological features characteristic of the AD brain, by combining an extensive set of histological and analytical tools. We report that the prominent somatic distribution of APP observed in control patients remarkably vanishes in human AD patients to the benefit of dense accumulations of extra-somatic APP, which surround dense-core amyloid plaques enriched in APP-Nter. These features are accentuated in patients with familial forms of the disease. Importantly, APP accumulations are enriched in phosphorylated tau and presynaptic proteins whereas they are depleted of post-synaptic proteins suggesting that the extra-somatic accumulations of APP are of presynaptic origin. Ultrastructural analyses unveil that APP concentrates in autophagosomes and in multivesicular bodies together with presynaptic vesicle proteins. Altogether, alteration of APP distribution and its accumulation together with presynaptic proteins around dense-core amyloid plaques is a key histopathological feature in AD, lending support to the notion that presynaptic failure is a strong physiopathological component of AD.
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Affiliation(s)
- Tomàs Jordà‐Siquier
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Melina Petrel
- University Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4BordeauxFrance
| | - Vladimir Kouskoff
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Una Smailovic
- Division of Neurogeriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and SocietyKarolinska InstitutetSolnaSweden
| | - Fabrice Cordelières
- University Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4BordeauxFrance
| | - Susanne Frykman
- Division of Neurogeriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and SocietyKarolinska InstitutetSolnaSweden
| | - Ulrike Müller
- Institute for Pharmacy and Molecular BiotechnologyHeidelbergGermany
| | - Christophe Mulle
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Gaël Barthet
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
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6
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Xu D, Yang P, Yang ZJ, Li QG, Ouyang YT, Yu T, Shangguan JH, Wan YY, Jiang LP, Qu XH, Han XJ. Blockage of Drp1 phosphorylation at Ser579 protects neurons against Aβ 1‑42‑induced degeneration. Mol Med Rep 2021; 24:657. [PMID: 34278489 PMCID: PMC8299198 DOI: 10.3892/mmr.2021.12296] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 06/24/2021] [Indexed: 01/13/2023] Open
Abstract
Alzheimer's disease (AD), one of the most common types of chronic neurodegenerative diseases, is pathologically characterized by the formation of amyloid β (Aβ) peptide-containing plaques and neurofibrillary tangles. Among Aβ peptides, Aβ1–42 induces neuronal toxicity and neurodegeneration. In our previous studies, Cdk5 was found to regulate Aβ1–42-induced mitochondrial fission via the phosphorylation of dynamin-related protein 1 (Drp1) at Ser579. However, whether blockage of Drp1 phosphorylation at Ser579 protects neurons against Aβ1–42-induced degeneration remains to be elucidated. Thus, the aim the present study was to examine the effect of mutant Drp1-S579A on neurodegeneration and its underlying mechanism. First, the phosphorylation-defect (phospho-defect) mutant, Lenti-Drp1-S579A was constructed. Phospho-defect Drp1-S579A expression was detected in primary cultures of mouse cortical neurons infected with Lenti-Drp1-S579A using western blotting and it was found to successfully attenuate the phosphorylation of endogenous Drp1 at Ser579. In primary neuronal cultures, the neuronal processes were evaluated under microscopy. Treatment with 10 µM Aβ1–42 significantly decreased dendritic density and length, spine outgrowth and synapse number. As expected, infection of neurons with Lenti-Drp1-S579A efficiently alleviated the inhibitory effect of Aβ1–42 on neurite outgrowth and synapse density. In addition, infection with Lenti-Drp1-S579A abolished the cleavage of caspase-3 and apoptosis in neurons exposed to Aβ1–42. Thus, the current data demonstrated that blockage of Drp1 phosphorylation at Ser579 may be an effective strategy to protect neurons against Aβ1–42-induced degeneration and apoptosis. These findings underline the therapeutic potential of targeting Drp1 in the treatment of AD.
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Affiliation(s)
- Dan Xu
- Institute of Geriatrics, Affiliated People's Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Ping Yang
- Department of Neurology, Affiliated People's Hospital of Nanchang University, Jiangxi 330006, P.R. China
| | - Zhang-Jian Yang
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Jiangxi 330006, P.R. China
| | - Qiu-Gen Li
- Institute of Geriatrics, Affiliated People's Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Ye-Tong Ouyang
- Department of Neurology, Affiliated People's Hospital of Nanchang University, Jiangxi 330006, P.R. China
| | - Ting Yu
- Department of Neurology, Affiliated People's Hospital of Nanchang University, Jiangxi 330006, P.R. China
| | - Jian-Hui Shangguan
- Department of Neurology, Affiliated People's Hospital of Nanchang University, Jiangxi 330006, P.R. China
| | - Yu-Ying Wan
- Department of Intra‑Hospital Infection Management, The Second Affiliated Hospital of Nanchang University, Jiangxi 330006, P.R. China
| | - Li-Ping Jiang
- Department of Pharmacology, School of Pharmaceutical Science, Nanchang University, Jiangxi 330006, P.R. China
| | - Xin-Hui Qu
- Institute of Geriatrics, Affiliated People's Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Xiao-Jian Han
- Institute of Geriatrics, Affiliated People's Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China
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7
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Sebastian Monasor L, Müller SA, Colombo AV, Tanrioever G, König J, Roth S, Liesz A, Berghofer A, Piechotta A, Prestel M, Saito T, Saido TC, Herms J, Willem M, Haass C, Lichtenthaler SF, Tahirovic S. Fibrillar Aβ triggers microglial proteome alterations and dysfunction in Alzheimer mouse models. eLife 2020; 9:54083. [PMID: 32510331 PMCID: PMC7279888 DOI: 10.7554/elife.54083] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 05/02/2020] [Indexed: 12/20/2022] Open
Abstract
Microglial dysfunction is a key pathological feature of Alzheimer's disease (AD), but little is known about proteome-wide changes in microglia during the course of AD and their functional consequences. Here, we performed an in-depth and time-resolved proteomic characterization of microglia in two mouse models of amyloid β (Aβ) pathology, the overexpression APPPS1 and the knock-in APP-NL-G-F (APP-KI) model. We identified a large panel of Microglial Aβ Response Proteins (MARPs) that reflect heterogeneity of microglial alterations during early, middle and advanced stages of Aβ deposition and occur earlier in the APPPS1 mice. Strikingly, the kinetic differences in proteomic profiles correlated with the presence of fibrillar Aβ, rather than dystrophic neurites, suggesting that fibrillar Aβ may trigger the AD-associated microglial phenotype and the observed functional decline. The identified microglial proteomic fingerprints of AD provide a valuable resource for functional studies of novel molecular targets and potential biomarkers for monitoring AD progression or therapeutic efficacy. Alzheimer’s disease is a progressive, irreversible brain disorder. Patients with Alzheimer’s have problems with memory and other mental skills, which lead to more severe cognitive decline and, eventually, premature death. This is due to increasing numbers of nerve cells in the brain dying over time. A distinctive feature of Alzheimer’s is the abnormally high accumulation of a protein called amyloid-β, which forms distinctive clumps in the brain termed ‘plaques’. The brain has a type of cells called the microglia that identify infections, toxic material and damaged cells, and prevent these from building up by clearing them away. In Alzheimer’s disease, however, the microglia do not work properly, which is thought to contribute to the accumulation of amyloid-β plaques. This means that people with mutations in the genes important for the microglia activity are also at higher risk of developing the disease. Although problems with the microglia play an important role in Alzheimer’s, researchers still do not fully understand why microglia stop working in the first place. It is also not known exactly when and how the microglia change as Alzheimer’s disease progresses. To unravel this mystery, Sebastian Monasor, Müller et al. carried out a detailed study of the molecular ‘fingerprints’ of microglia at each key stage of Alzheimer’s disease. The experiments used microglia cells from two different strains of genetically altered mice, both of which develop the hallmarks of Alzheimer’s disease, including amyloid-β plaques, at similar rates. Analysis of the proteins in microglia cells from both strains revealed distinctive, large-scale changes corresponding to successive stages of the disease – reflecting the gradual accumulation of plaques. Obvious defects in microglia function also appeared soon after plaques started to build up. Microscopy imaging of the brain tissue showed that although amyloid-β plaques appeared at the same time, they looked different in each mouse strain. In one, plaques were more compact, while in the other, plaques appeared ‘fluffier’, like cotton wool. In mice with more compacted plaques, microglia recognized the plaques earlier and stopped working sooner, suggesting that plaque structure and microglia defects could be linked. These results shed new light on the role of microglia and their changing protein ‘signals’ during the different stages of Alzheimer’s disease. In the future, this information could help identify people at risk for the disease, so that they can be treated as soon as possible, and to design new therapies to make microglia work again.
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Affiliation(s)
- Laura Sebastian Monasor
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Graduate School of Systemic Neuroscience, Ludwig-Maximilians-University, Munich, Germany
| | - Stephan A Müller
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | | | - Gaye Tanrioever
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany.,Department of Cellular Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Jasmin König
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Faculty of Chemistry, Technical University of Munich, Garching, Germany
| | - Stefan Roth
- Institute for Stroke and Dementia Research (ISD), University Hospital, LMU, Munich, Germany
| | - Arthur Liesz
- Institute for Stroke and Dementia Research (ISD), University Hospital, LMU, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Anna Berghofer
- Neuroproteomics, School of Medicine, Klinikum Rechts der Isar, Technical University, Munich, Germany
| | - Anke Piechotta
- Department of Molecular Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology, Halle, Germany
| | - Matthias Prestel
- Institute for Stroke and Dementia Research (ISD), University Hospital, LMU, Munich, Germany
| | - Takashi Saito
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science Institute, Wako, Japan.,Department of Neurocognitive Science, Nagoya City University Graduate School of Medical Science, Nagoya, Japan
| | - Takaomi C Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science Institute, Wako, Japan
| | - Jochen Herms
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,Center for Neuropathology and Prion Research, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Michael Willem
- Biomedical Center (BMC), Ludwig-Maximilians Universität München, Munich, Germany
| | - Christian Haass
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,Biomedical Center (BMC), Ludwig-Maximilians Universität München, Munich, Germany
| | - Stefan F Lichtenthaler
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,Neuroproteomics, School of Medicine, Klinikum Rechts der Isar, Technical University, Munich, Germany
| | - Sabina Tahirovic
- German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
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8
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Spangenberg E, Severson PL, Hohsfield LA, Crapser J, Zhang J, Burton EA, Zhang Y, Spevak W, Lin J, Phan NY, Habets G, Rymar A, Tsang G, Walters J, Nespi M, Singh P, Broome S, Ibrahim P, Zhang C, Bollag G, West BL, Green KN. Sustained microglial depletion with CSF1R inhibitor impairs parenchymal plaque development in an Alzheimer's disease model. Nat Commun 2019; 10:3758. [PMID: 31434879 PMCID: PMC6704256 DOI: 10.1038/s41467-019-11674-z] [Citation(s) in RCA: 428] [Impact Index Per Article: 85.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 07/26/2019] [Indexed: 01/07/2023] Open
Abstract
Many risk genes for the development of Alzheimer's disease (AD) are exclusively or highly expressed in myeloid cells. Microglia are dependent on colony-stimulating factor 1 receptor (CSF1R) signaling for their survival. We designed and synthesized a highly selective brain-penetrant CSF1R inhibitor (PLX5622) allowing for extended and specific microglial elimination, preceding and during pathology development. We find that in the 5xFAD mouse model of AD, plaques fail to form in the parenchymal space following microglial depletion, except in areas containing surviving microglia. Instead, Aβ deposits in cortical blood vessels reminiscent of cerebral amyloid angiopathy. Altered gene expression in the 5xFAD hippocampus is also reversed by the absence of microglia. Transcriptional analyses of the residual plaque-forming microglia show they exhibit a disease-associated microglia profile. Collectively, we describe the structure, formulation, and efficacy of PLX5622, which allows for sustained microglial depletion and identify roles of microglia in initiating plaque pathogenesis.
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Affiliation(s)
- Elizabeth Spangenberg
- Department of Neurobiology and Behavior, University of California Irvine (UCI), Irvine, CA, 92697, USA
| | | | - Lindsay A Hohsfield
- Department of Neurobiology and Behavior, University of California Irvine (UCI), Irvine, CA, 92697, USA
| | - Joshua Crapser
- Department of Neurobiology and Behavior, University of California Irvine (UCI), Irvine, CA, 92697, USA
| | | | | | | | | | - Jack Lin
- Plexxikon Inc, Berkeley, CA, 94710, USA
| | - Nicole Y Phan
- Department of Neurobiology and Behavior, University of California Irvine (UCI), Irvine, CA, 92697, USA
| | | | | | | | | | | | | | | | | | | | | | | | - Kim N Green
- Department of Neurobiology and Behavior, University of California Irvine (UCI), Irvine, CA, 92697, USA.
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9
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El Hajj H, Savage JC, Bisht K, Parent M, Vallières L, Rivest S, Tremblay MÈ. Ultrastructural evidence of microglial heterogeneity in Alzheimer's disease amyloid pathology. J Neuroinflammation 2019; 16:87. [PMID: 30992040 PMCID: PMC6469225 DOI: 10.1186/s12974-019-1473-9] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 04/01/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is the most common neurodegenerative disease, characterized by the deposition of extracellular fibrillar amyloid β (fΑβ) and the intracellular accumulation of neurofibrillary tangles. As AD progresses, Aβ drives a robust and prolonged inflammatory response via its recognition by microglia, the brain's immune cells. Microglial reactivity to fAβ plaques may impair their normal surveillance duties, facilitating synaptic loss and neuronal death, as well as cognitive decline in AD. METHODS In the current study, we performed correlative light, transmission, and scanning electron microscopy to provide insights into microglial structural and functional heterogeneity. We analyzed microglial cell bodies and processes in areas containing fAβ plaques and neuronal dystrophy, dystrophy only, or appearing healthy, among the hippocampus CA1 of 14-month-old APPSwe-PS1Δe9 mice versus wild-type littermates. RESULTS Our quantitative analysis revealed that microglial cell bodies in the AD model mice were larger and displayed ultrastructural signs of cellular stress, especially nearby plaques. Microglial cell bodies and processes were overall less phagocytic in AD model mice. However, they contained increased fibrillar materials and non-empty inclusions proximal to plaques. Microglial cell bodies and processes in AD model mice also displayed reduced association with extracellular space pockets that contained debris. In addition, microglial processes in healthy subregions of AD model mice encircled synaptic elements more often compared with plaque-associated processes. These observations in mice were qualitatively replicated in post-mortem hippocampal samples from two patients with AD (Braak stage 5). CONCLUSION Together, our findings identify at the ultrastructural level distinct microglial transformations common to mouse and human in association with amyloid pathology.
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Affiliation(s)
- Hassan El Hajj
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
| | - Julie C. Savage
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
| | - Kanchan Bisht
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
| | - Martin Parent
- Département de psychiatrie et de neurosciences, Faculté de médecine, Université Laval, Quebec, QC Canada
- CERVO Brain Research Center, Quebec, QC Canada
| | - Luc Vallières
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Quebec, QC Canada
| | - Serge Rivest
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Quebec, QC Canada
| | - Marie-Ève Tremblay
- Axe neurosciences, Centre de recherche du CHU de Québec-Université Laval, 2705, boulevard Laurier, T2-50, Quebec, QC G1V 4G2 Canada
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Quebec, QC Canada
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10
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Castro MA, Hadziselimovic A, Sanders CR. The vexing complexity of the amyloidogenic pathway. Protein Sci 2019; 28:1177-1193. [PMID: 30897251 DOI: 10.1002/pro.3606] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 03/18/2019] [Accepted: 03/18/2019] [Indexed: 02/06/2023]
Abstract
The role of the amyloidogenic pathway in the etiology of Alzheimer's disease (AD), particularly the common sporadic late onset forms of the disease, is controversial. To some degree, this is a consequence of the failure of drug and therapeutic antibody trials based either on targeting the proteases in this pathway or its amyloid end products. Here, we explore the formidable complexity of the biochemistry and cell biology associated with this pathway. For example, we review evidence that the immediate precursor of amyloid-β, the C99 domain of the amyloid precursor protein (APP), may itself be toxic. We also review important new results that appear to finally establish a direct genetic link between mutations in APP and the sporadic forms of AD. Based on the complexity of amyloidogenesis, it seems possible that a major contributor to the failure of related drug trials is that we have an incomplete understanding of this pathway and how it is linked to Alzheimer's pathogenesis. If so, this highlights a need for further characterization of this pathway, not its abandonment.
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Affiliation(s)
- Manuel A Castro
- Departments of Biochemistry and Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37240
| | - Arina Hadziselimovic
- Departments of Biochemistry and Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37240
| | - Charles R Sanders
- Departments of Biochemistry and Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37240
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11
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Adlimoghaddam A, Snow WM, Stortz G, Perez C, Djordjevic J, Goertzen AL, Ko JH, Albensi BC. Regional hypometabolism in the 3xTg mouse model of Alzheimer's disease. Neurobiol Dis 2019; 127:264-277. [PMID: 30878533 DOI: 10.1016/j.nbd.2019.03.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 02/22/2019] [Accepted: 03/12/2019] [Indexed: 12/28/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive age-related neurodegenerative disease. Although neurofibrillary tangles and amyloid beta are classic hallmarks of AD, the earliest deficits in AD progression may be caused by unknown factors. One suspected factor has to do with brain energy metabolism. To investigate this factor, brain metabolic activity in 3xTg-AD mice and age-matched controls were measured with FDG-PET. Significant hypometabolic changes (p < .01) in brain metabolism were detected in the cortical piriform and insular regions of AD brains relative to controls. These regions are associated with olfaction, which is a potential clinical marker for AD progression as well as neurogenesis. The activity of the terminal component of the mitochondrial respiratory chain (complex IV) and the expression of complex I-V were significantly decreased (p < .05), suggesting that impaired metabolic activity coupled with impaired oxidative phosphorylation leads to decreased mitochondrial bioenergetics and subsequent Neurodegeneration. Although there is an association between neuroinflammatory pathological markers (microglial) and hypometabolism in AD, there was no association found between neuropathological (Aβ, tau, and astrocytes) and functional changes in AD sensitive brain regions, also suggesting that brain hypometabolism occurs prior to AD pathology. Therefore, targeting metabolic mechanisms in cortical piriform and insular regions at early stages may be a promising approach for preventing, slowing, and/or blocking the onset of AD and preserving neurogenesis.
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Affiliation(s)
- Aida Adlimoghaddam
- St. Boniface Hospital Research, Canada; Dept. of Pharmacology & Therapeutics, University of Manitoba, Canada.
| | | | | | - Claudia Perez
- St. Boniface Hospital Research, Canada; Dept. of Pharmacology & Therapeutics, University of Manitoba, Canada
| | - Jelena Djordjevic
- St. Boniface Hospital Research, Canada; Dept. of Pharmacology & Therapeutics, University of Manitoba, Canada
| | | | - Ji Hyun Ko
- Dept. of Human Anatomy and Cell Science, University of Manitoba, Canada; Health Sciences Centre, Canada
| | - Benedict C Albensi
- St. Boniface Hospital Research, Canada; Dept. of Pharmacology & Therapeutics, University of Manitoba, Canada.
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12
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Kim W, Ma L, Lomoio S, Willen R, Lombardo S, Dong J, Haydon PG, Tesco G. BACE1 elevation engendered by GGA3 deletion increases β-amyloid pathology in association with APP elevation and decreased CHL1 processing in 5XFAD mice. Mol Neurodegener 2018; 13:6. [PMID: 29391027 PMCID: PMC5796504 DOI: 10.1186/s13024-018-0239-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 01/24/2018] [Indexed: 12/28/2022] Open
Abstract
Background β-site amyloid precursor protein cleaving enzyme 1 (BACE1) is the rate-limiting enzyme in the production of amyloid beta (Aβ), the toxic peptide that accumulates in the brains of Alzheimer’s disease (AD) patients. Our previous studies have shown that the clathrin adaptor Golgi-localized γ-ear-containing ARF binding protein 3 (GGA3) plays a key role in the trafficking of BACE1 to lysosomes, where it is normally degraded. GGA3 depletion results in BACE1 stabilization both in vitro and in vivo. Moreover, levels of GGA3 are reduced and inversely related to BACE1 levels in post-mortem brains of AD patients. Method In order to assess the effect of GGA3 deletion on AD-like phenotypes, we crossed GGA3 −/− mice with 5XFAD mice. BACE1-mediated processing of APP and the cell adhesion molecule L1 like protein (CHL1) was measured as well as levels of Aβ42 and amyloid burden. Results In 5XFAD mice, we found that hippocampal and cortical levels of GGA3 decreased while BACE1 levels increased with age, similar to what is observed in human AD brains. GGA3 deletion prevented age-dependent elevation of BACE1 in GGA3KO;5XFAD mice. We also found that GGA3 deletion resulted in increased hippocampal levels of Aβ42 and amyloid burden in 5XFAD mice at 12 months of age. While levels of BACE1 did not change with age and gender in GGAKO;5XFAD mice, amyloid precursor protein (APP) levels increased with age and were higher in female mice. Moreover, elevation of APP was associated with a decreased BACE1-mediated processing of CHL1 not only in 12 months old 5XFAD mice but also in human brains from subjects affected by Down syndrome, most likely due to substrate competition. Conclusion This study demonstrates that GGA3 depletion is a leading candidate mechanism underlying elevation of BACE1 in AD. Furthermore, our findings suggest that BACE1 inhibition could exacerbate mechanism-based side effects in conditions associated with APP elevation (e.g. Down syndrome) owing to impairment of BACE1-mediated processing of CHL1. Therefore, therapeutic approaches aimed to restore GGA3 function and to prevent the down stream effects of its depletion (e.g. BACE1 elevation) represent an attractive alternative to BACE inhibition for the prevention/treatment of AD. Electronic supplementary material The online version of this article (10.1186/s13024-018-0239-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- WonHee Kim
- Alzheimer's Disease Research Laboratory, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA.,Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA
| | - Liang Ma
- Alzheimer's Disease Research Laboratory, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA.,Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA
| | - Selene Lomoio
- Alzheimer's Disease Research Laboratory, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA.,Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA
| | - Rachel Willen
- Alzheimer's Disease Research Laboratory, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA.,Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA
| | - Sylvia Lombardo
- Alzheimer's Disease Research Laboratory, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA.,Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA
| | - Jinghui Dong
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA
| | - Philip G Haydon
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA
| | - Giuseppina Tesco
- Alzheimer's Disease Research Laboratory, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA. .,Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA, 02111, USA.
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13
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Gowrishankar S, Wu Y, Ferguson SM. Impaired JIP3-dependent axonal lysosome transport promotes amyloid plaque pathology. J Cell Biol 2017; 216:3291-3305. [PMID: 28784610 PMCID: PMC5626538 DOI: 10.1083/jcb.201612148] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/18/2017] [Accepted: 07/06/2017] [Indexed: 12/29/2022] Open
Abstract
Axonal lysosomes accumulate abnormally in Alzheimer’s disease brains. However, whether and how such lysosomes contribute to disease pathology has been unclear. Gowrishankar et al. show that the JIP3-dependent transport of axonal lysosomes negatively regulates amyloid precursor protein processing into amyloidogenic peptides. Lysosomes robustly accumulate within axonal swellings at Alzheimer’s disease (AD) amyloid plaques. However, the underlying mechanisms and disease relevance of such lysosome accumulations are not well understood. Motivated by these problems, we identified JNK-interacting protein 3 (JIP3) as an important regulator of axonal lysosome transport and maturation. JIP3 knockout mouse neuron primary cultures accumulate lysosomes within focal axonal swellings that resemble the dystrophic axons at amyloid plaques. These swellings contain high levels of amyloid precursor protein processing enzymes (BACE1 and presenilin 2) and are accompanied by elevated Aβ peptide levels. The in vivo importance of the JIP3-dependent regulation of axonal lysosomes was revealed by the worsening of the amyloid plaque pathology arising from JIP3 haploinsufficiency in a mouse model of AD. These results establish the critical role of JIP3-dependent axonal lysosome transport in regulating amyloidogenic amyloid precursor protein processing and support a model wherein Aβ production is amplified by plaque-induced axonal lysosome transport defects.
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Affiliation(s)
- Swetha Gowrishankar
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT
| | - Yumei Wu
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT.,Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT
| | - Shawn M Ferguson
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT .,Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT
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14
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Zhao R, Hu W, Tsai J, Li W, Gan WB. Microglia limit the expansion of β-amyloid plaques in a mouse model of Alzheimer's disease. Mol Neurodegener 2017; 12:47. [PMID: 28606182 PMCID: PMC5468952 DOI: 10.1186/s13024-017-0188-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 06/02/2017] [Indexed: 11/25/2022] Open
Abstract
Background Microglia are known as resident immune cells in the brain. β-amyloid (Aβ) plaques in the brain of Alzheimer’s disease (AD) are surrounded by microglia, but whether and how microglia affect the formation and maintenance of plaques remains controversial. Methods We depleted microglia by injecting diphtheria toxin (DT) in CX3CR1CreER/+:R26DTR/+ (CX3CR1-iDTR) mice crossed with APPswe/PSEN1dE9 (APP/PS1) mice. Intravital time-lapse imaging was performed to examine changes in the number and size of Congo Red-labeled amyloid plaques over 1–2 weeks. We also examined spine density and shaft diameter of dendrites passing through plaques in a PSAPP mouse model of AD (PS1M146L line 6.2 × Tg2576) crossed with Thy1 YFP H-line mice. Results We found that DT administration to CX3CR1-iDTR mice efficiently ablated microglia within one week and that microglia repopulated in the second week after DT administration. Microglia depletion didn’t affect the number of amyloid plaques, but led to ~13% increase in the size of Aβ plaques within one week. Moreover, microglia repopulation was associated with the stabilization of plaque size during the second week. In addition, we found dendritic spine loss and shaft atrophy in the distal parts of dendrites passing through plaques. Conclusion Our results demonstrate the important role of microglia in limiting the growth of Aβ plaques and plaque-associated disruption of neuronal connection. Electronic supplementary material The online version of this article (doi:10.1186/s13024-017-0188-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ruohe Zhao
- Drug Discovery Center, Peking University Shenzhen Graduate School, Shenzhen, 518055, China.,Skirball Institute, New York University School of Medicine, New York, NY, 10016, USA
| | - Wanling Hu
- Drug Discovery Center, Peking University Shenzhen Graduate School, Shenzhen, 518055, China
| | - Julia Tsai
- Skirball Institute, New York University School of Medicine, New York, NY, 10016, USA
| | - Wei Li
- Drug Discovery Center, Peking University Shenzhen Graduate School, Shenzhen, 518055, China. .,Skirball Institute, New York University School of Medicine, New York, NY, 10016, USA.
| | - Wen-Biao Gan
- Drug Discovery Center, Peking University Shenzhen Graduate School, Shenzhen, 518055, China. .,Skirball Institute, New York University School of Medicine, New York, NY, 10016, USA.
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15
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Watamura N, Toba J, Yoshii A, Nikkuni M, Ohshima T. Colocalization of phosphorylated forms of WAVE1, CRMP2, and tau in Alzheimer's disease model mice: Involvement of Cdk5 phosphorylation and the effect of ATRA treatment. J Neurosci Res 2015; 94:15-26. [PMID: 26400044 DOI: 10.1002/jnr.23674] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 08/18/2015] [Accepted: 09/08/2015] [Indexed: 12/28/2022]
Abstract
Alzheimer's disease (AD) is the most common type of dementia among the elderly. Neurofibrillary tangles (NFTs), a major pathological hallmark of AD, are composed of tau protein that is hyperphosphorylated by cyclin-dependent kinase 5 (Cdk5) and glycogen synthase kinase 3β (GSK3β). NFTs also contain Wiskott-Aldrich syndrome protein family verprolin-homologous protein 1 (WAVE1) and collapsin response-mediator protein 2 (CRMP2). Although Cdk5 is known to phosphorylate tau, WAVE1, and CRMP2, the significance of this with respect to NFT formation remains to be elucidated. This study examines the involvement of phosphorylated (p-) CRMP2 and WAVE1 in p-tau aggregates using a triple-transgenic (3×Tg; APPswe/PS1M146V/tauP301L) AD mouse model. First, we verified the colocalization of p-WAVE1 and p-CRMP2 with aggregated hyperphosphorylated tau in the hippocampus at 23 months of age. Biochemical analysis revealed the inclusion of p-WAVE1, p-CRMP2, and tau in the sarkosyl-insoluble fractions of hippocampal homogenates. To test the significance of phosphorylation of these proteins further, we administered all-trans-retinoic acid (ATRA) to the 3×Tg mice, which downregulates Cdk5 and GSK3β activity. In ATRA-treated mice, fewer and smaller tau aggregates were observed compared with non-ATRA-treated mice. These results suggest the possibility of novel therapeutic target molecules for preventing tau pathology.
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Affiliation(s)
- Naoto Watamura
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Junya Toba
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Aya Yoshii
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Miyu Nikkuni
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
| | - Toshio Ohshima
- Laboratory for Molecular Brain Science, Department of Life Science and Medical Bioscience, Waseda University, Tokyo, Japan
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16
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Li JM, Liu C, Hu X, Cai Y, Ma C, Luo XG, Yan XX. Inverse correlation between Alzheimer's disease and cancer: implication for a strong impact of regenerative propensity on neurodegeneration? BMC Neurol 2014; 14:211. [PMID: 25394409 PMCID: PMC4232711 DOI: 10.1186/s12883-014-0211-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/24/2014] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Recent studies have revealed an inverse epidemiological correlation between Alzheimer's disease (AD) and cancer - patients with AD show a reduced risk of cancer, while cancer survivors are less likely to develop AD. These late discoveries in human subjects call for explorative studies to unlock the underlying biological mechanism, but also may shed new light on conceptual interrogation of the principal pathogenic players in AD etiology. DISCUSSION Here we hypothesize that this negative correlation reflects a rebalance of biosynthetic propensity between body systems under the two disease statuses. In normal condition the body cellular systems are maintained homeostatically under a balanced cell degenerative vs. surviving/regenerative propensities, determined by biosynthetic resources for anabolic processing. AD pathogenesis involves neurodegeneration but also aberrant regenerative, or reactive anabolic, burden, while cancer development is driving by uncontrolled proliferation inherent with excessive anabolic activity. The aberrant neural regenerative propensity in AD pathogenesis and the uncontrolled cellular proliferative propensity in cancer pathogeneses can manifest as competitive processes, which could result in the inverse epidemiological correlation seen among the elderly. SUMMARY The reduced prevalence of AD in cancer survivors may implicate a strong impact of aberrant neural regenerative burden in neurodegeneration. Further explorative studies into the inverse correlation between AD and cancer should include examinations of the proliferative propensity of tumor cells in AD models, and the development of AD-like neuropathology in cancer models as well as following anti-proliferative drug treatment.
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Affiliation(s)
- Jian-Ming Li
- />Department of Anatomy and Neurobiology, Central South University School of Basic Medical Science, Changsha, 410013 Hunan China
- />Neuroscience Research Center, Changsha Medical University, Changsha, 410219 Hunan China
| | - Chao Liu
- />Department of Anatomy and Neurobiology, Central South University School of Basic Medical Science, Changsha, 410013 Hunan China
- />Department of Neurology, The First Hospital of Changsha, Changsha, 410005 Hunan China
| | - Xia Hu
- />Department of Anatomy and Neurobiology, Central South University School of Basic Medical Science, Changsha, 410013 Hunan China
| | - Yan Cai
- />Department of Anatomy and Neurobiology, Central South University School of Basic Medical Science, Changsha, 410013 Hunan China
| | - Chao Ma
- />Department of Human Anatomy, Histology & Embryology, Institute of Basic Medical Sciences, Neuroscience Center, Chinese Academy of Medical Sciences; School of Basic Medicine, Peking Union Medical College, Beijing, 100730 China
| | - Xue-Gang Luo
- />Department of Anatomy and Neurobiology, Central South University School of Basic Medical Science, Changsha, 410013 Hunan China
| | - Xiao-Xin Yan
- />Department of Anatomy and Neurobiology, Central South University School of Basic Medical Science, Changsha, 410013 Hunan China
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17
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Pensalfini A, Albay R, Rasool S, Wu JW, Hatami A, Arai H, Margol L, Milton S, Poon WW, Corrada MM, Kawas CH, Glabe CG. Intracellular amyloid and the neuronal origin of Alzheimer neuritic plaques. Neurobiol Dis 2014; 71:53-61. [PMID: 25092575 DOI: 10.1016/j.nbd.2014.07.011] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 05/24/2014] [Accepted: 07/08/2014] [Indexed: 01/19/2023] Open
Abstract
Genetic analysis of familial forms of Alzheimer's disease (AD) causally links the proteolytic processing of the amyloid precursor protein (APP) and AD. However, the specific type of amyloid and mechanisms of amyloid pathogenesis remain unclear. We conducted a detailed analysis of intracellular amyloid with an aggregation specific conformation dependent monoclonal antibody, M78, raised against fibrillar Aß42. M78 immunoreactivity colocalizes with Aß and the carboxyl terminus of APP (APP-CTF) immunoreactivities in perinuclear compartments at intermediate times in 10month 3XTg-AD mice, indicating that this represents misfolded and aggregated protein rather than normally folded APP. At 12months, M78 immunoreactivity also accumulates in the nucleus. Neuritic plaques at 12months display the same spatial organization of centrally colocalized M78, diffuse chromatin and neuronal nuclear NeuN staining surrounded by peripheral M78 and APP-CTF immunoreactivity as observed in neurons, indicating that neuritic plaques arise from degenerating neurons with intracellular amyloid immunoreactivity. The same staining pattern was observed in neuritic plaques in human AD brains, showing elevated intracellular M78 immunoreactivity at intermediate stages of amyloid pathology (Braak A and B) compared to no amyloid pathology and late stage amyloid pathology (Braak 0 and C, respectively). These results indicate that intraneuronal protein aggregation and amyloid accumulation is an early event in AD and that neuritic plaques are initiated by the degeneration and death of neurons by a mechanism that may be related to the formation of extracellular traps by neutrophils.
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Affiliation(s)
- Anna Pensalfini
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.
| | - Ricardo Albay
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Suhail Rasool
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Jessica W Wu
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Asa Hatami
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Hiromi Arai
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Lawrence Margol
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Saskia Milton
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
| | - Wayne W Poon
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697, USA
| | - Maria M Corrada
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697, USA; Department of Neurology, University of California, Irvine, CA 92697, USA
| | - Claudia H Kawas
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA 92697, USA; Department of Neurology, University of California, Irvine, CA 92697, USA; Department of Neurobiology & Behavior, University of California, Irvine, CA 92697, USA
| | - Charles G Glabe
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA; Biochemistry Department and Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
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18
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Ajit D, Woods LT, Camden JM, Thebeau CN, El-Sayed FG, Greeson GW, Erb L, Petris MJ, Miller DC, Sun GY, Weisman GA. Loss of P2Y₂ nucleotide receptors enhances early pathology in the TgCRND8 mouse model of Alzheimer's disease. Mol Neurobiol 2013; 49:1031-42. [PMID: 24193664 DOI: 10.1007/s12035-013-8577-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 10/21/2013] [Indexed: 11/26/2022]
Abstract
Neuroinflammation is a prominent feature in Alzheimer's disease (AD) and activation of the brain's innate immune system, particularly microglia, has been postulated to both retard and accelerate AD progression. Recent studies indicate that the G protein-coupled P2Y2 nucleotide receptor (P2Y2R) is an important regulator of innate immunity by assisting in the recruitment of monocytes to injured tissue, neutrophils to bacterial infections and eosinophils to allergen-infected lungs. In this study, we investigated the role of the P2Y2R in progression of an AD-like phenotype in the TgCRND8 mouse model that expresses Swedish and Indiana mutations in amyloid precursor protein (APP). Our results indicate that P2Y 2 R expression is upregulated in TgCRND8 mouse brain within 10 weeks of age and then decreases after 25 weeks of age, as compared to littermate controls expressing low levels of the P2Y 2 R. TgCRND8 mice with homozygous P2Y 2 R deletion survive less than 5 weeks, whereas mice with heterozygous P2Y 2 R deletion survive for 12 weeks, a time point when TgCRND8 mice are fully viable. Heterozygous P2Y 2 R deletion in TgCRND8 mice increased β-amyloid (Aβ) plaque load and soluble Aβ1-42 levels in the cerebral cortex and hippocampus, decreased the expression of the microglial marker CD11b in these brain regions and caused neurological deficits within 10 weeks of age, as compared to age-matched TgCRND8 mice. These findings suggest that the P2Y2R is important for the recruitment and activation of microglial cells in the TgCRND8 mouse brain and that the P2Y2R may regulate neuroprotective mechanisms through microglia-mediated clearance of Aβ that when lost can accelerate the onset of an AD-like phenotype in the TgCRND8 mouse.
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Affiliation(s)
- Deepa Ajit
- Department of Biochemistry, University of Missouri, 540E Life Sciences Center, 1201 Rollins Road, Columbia, MO, 65211-7310, USA
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The Alzheimer's β-secretase BACE1 localizes to normal presynaptic terminals and to dystrophic presynaptic terminals surrounding amyloid plaques. Acta Neuropathol 2013; 126:329-52. [PMID: 23820808 PMCID: PMC3753469 DOI: 10.1007/s00401-013-1152-3] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 06/20/2013] [Indexed: 01/18/2023]
Abstract
β-Site amyloid precursor protein (APP) cleaving enzyme-1 (BACE1) is the β-secretase that initiates Aβ production in Alzheimer’s disease (AD). BACE1 levels are increased in AD, which could contribute to pathogenesis, yet the mechanism of BACE1 elevation is unclear. Furthermore, the normal function of BACE1 is poorly understood. We localized BACE1 in the brain at both the light and electron microscopic levels to gain insight into normal and pathophysiologic roles of BACE1 in health and AD, respectively. Our findings provide the first ultrastructural evidence that BACE1 localizes to vesicles (likely endosomes) in normal hippocampal mossy fiber terminals of both non-transgenic and APP transgenic (5XFAD) mouse brains. In some instances, BACE1-positive vesicles were located near active zones, implying a function for BACE1 at the synapse. In addition, BACE1 accumulated in swollen dystrophic autophagosome-poor presynaptic terminals surrounding amyloid plaques in 5XFAD cortex and hippocampus. Importantly, accumulations of BACE1 and APP co-localized in presynaptic dystrophies, implying increased BACE1 processing of APP in peri-plaque regions. In primary cortical neuron cultures, treatment with the lysosomal protease inhibitor leupeptin caused BACE1 levels to increase; however, exposure of neurons to the autophagy inducer trehalose did not reduce BACE1 levels. This suggests that BACE1 is degraded by lysosomes but not by autophagy. Our results imply that BACE1 elevation in AD could be linked to decreased lysosomal degradation of BACE1 within dystrophic presynaptic terminals. Elevated BACE1 and APP levels in plaque-associated presynaptic dystrophies could increase local peri-plaque Aβ generation and accelerate amyloid plaque growth in AD.
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Increased binding of peripheral benzodiazepine receptor in mild cognitive impairment-dementia converters measured by positron emission tomography with [¹¹C]DAA1106. Psychiatry Res 2012; 203:67-74. [PMID: 22892349 DOI: 10.1016/j.pscychresns.2011.08.013] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 08/07/2011] [Accepted: 08/29/2011] [Indexed: 11/22/2022]
Abstract
Subjects with mild cognitive impairment (MCI) have "prodromal or incipient" dementia with neuropathological changes. Peripheral benzodiazepine receptor (PBR) binding was shown to reflect activated microglia, one of the predictive biomarkers of conversion to dementia. We sought to evaluate PBR binding in MCI subjects using positron emission tomography (PET). PET scans with [¹¹C]DAA1106, a potent and selective ligand for PBR, were performed on seven MCI subjects, 10 patients with Alzheimer's disease (AD) and 10 age-matched control subjects. PBR binding in the regions of interest was quantified by binding potential (BP). Five MCI subjects were clinically followed for 5 years after their initial PET scans. [¹¹C]DAA1106 binding to PBR was significantly increased in widespread areas in MCI subjects when compared to healthy controls. We found no significant difference in BP between MCI and AD patients. MCI subjects with [¹¹C]DAA1106 binding values higher than the control mean +0.5 standard deviation (S.D.) developed dementia within 5 years. Our finding of higher DAA binding in MCI subjects indicated that microglial activation may occur before the onset of dementia. In vivo detection of microglial activation may provide useful prognostic information with respect to stratifying MCI subjects at increased risk of dementia.
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Guo Q, Li H, Gaddam SSK, Justice NJ, Robertson CS, Zheng H. Amyloid precursor protein revisited: neuron-specific expression and highly stable nature of soluble derivatives. J Biol Chem 2011; 287:2437-45. [PMID: 22144675 DOI: 10.1074/jbc.m111.315051] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
APP processing and amyloid-β production play a central role in Alzheimer disease pathogenesis. APP has been considered a ubiquitously expressed protein. In addition to amyloid-β, α- or β-secretase-dependent cleavage of APP also generates soluble secreted APP (APPsα or APPsβ, respectively). Interestingly, APPsβ has been shown to be subject to further cleavage to create an N-APP fragment that binds to the DR6 death receptor and mediates axon pruning and degeneration under trophic factor withdrawal conditions. By performing APP immunocytochemical staining, we found that, unexpectedly, many antibodies yielded nonspecific staining in APP-null samples. Screening of a series of antibodies allowed us to identify a rabbit monoclonal antibody Y188 that is highly specific for APP and prompted us to re-examine the expression, localization, and stability of endogenous APP and APPsβ in wild-type and in APPsβ knock-in mice, respectively. In contrast to earlier studies, we found that APP is specifically expressed in neurons and that its expression cannot be detected in major types of glial cells under basal or neuroinflammatory conditions. Both APPsα and APPsβ are highly stable in the central nervous system (CNS) and do not undergo further cleavage with or without trophic factor support. Our results clarify several key questions with regard to the fundamental properties of APP and offer critical cellular insights into the pathophysiology of APP.
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Affiliation(s)
- Qinxi Guo
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas 77030, USA
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Kedikian G, Heredia F, Salvador VR, Raimunda D, Isoardi N, Heredia L, Lorenzo A. Secreted amyloid precursor protein and holo-APP bind amyloid beta through distinct domains eliciting different toxic responses on hippocampal neurons. J Neurosci Res 2010; 88:1795-803. [PMID: 20155808 DOI: 10.1002/jnr.22347] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Amyloid beta (Abeta) is a metabolic product of Abeta precursor protein (APP). Deposition of Abeta in the brain and neuronal degeneration are characteristic hallmarks of Alzheimer's disease (AD). Abeta induces neuronal degeneration, but the mechanism of neurotoxicity remains elusive. Increasing evidence implicates APP as a receptor-like protein for Abeta fibrils (fAbeta). In this study, we present further experimental support for the direct interaction of APP with fAbeta and for its involvement in Abeta neurotoxicity. Using recombinant purified holo-APP (h-APP), we have shown that it directly binds fAbeta. Employing deletion mutant forms of APP, we show that two different sequences are involved in the binding of APP to fAbeta. One sequence in the n-terminus of APP is required for binding of fAbeta to secreted APP (s-APP) but not to h-APP. In addition, the extracellular juxtamembrane Abeta-sequence mediates binding of fAbeta to h-APP but not to s-APP. Deletion of the extracellular juxtamembrane Abeta sequence abolishes abnormal h-APP accumulation and toxicity induced by fAbeta deposition, whereas deletions in the n-terminus of APP do not affect Abeta toxicity. These experiments show that interaction of toxic Abeta species with its membrane-anchored parental protein promotes toxicity in hippocampal neurons, adding further support to an Abeta-receptor-like function of APP directly implicated in neuronal degeneration in AD.
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Affiliation(s)
- Gabriela Kedikian
- Laboratory of Experimental Neuropathology, Instituto de Investigación Médica "Mercedes y Martín Ferreyra," INIMEC-CONICET, Córdoba, Argentina
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Polazzi E, Monti B. Microglia and neuroprotection: from in vitro studies to therapeutic applications. Prog Neurobiol 2010; 92:293-315. [PMID: 20609379 DOI: 10.1016/j.pneurobio.2010.06.009] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 06/21/2010] [Accepted: 06/22/2010] [Indexed: 12/12/2022]
Abstract
Microglia are the main immune cells in the brain, playing a role in both physiological and pathological conditions. Microglial involvement in neurodegenerative diseases is well-established, being microglial activation and neuroinflammation common features of these neuropathologies. Microglial activation has been considered harmful for neurons, but inflammatory state is not only associated with neurotoxic consequences, but also with neuroprotective effects, such as phagocytosis of dead neurons and clearance of debris. This brought to the idea of protective autoimmunity in the brain and to devise immunomodulatory therapies, aimed to specifically increase neuroprotective aspects of microglia. During the last years, several data supported the intrinsic neuroprotective function of microglia through the release of neuroprotective molecules. These data led to change the traditional view of microglia in neurodegenerative diseases: from the idea that these cells play an detrimental role for neurons due to a gain of their inflammatory function, to the proposal of a loss of microglial neuroprotective function as a causing factor in neuropathologies. This "microglial dysfunction hypothesis" points at the importance of understanding the mechanisms of microglial-mediated neuroprotection to develop new therapies for neurodegenerative diseases. In vitro models are very important to clarify the basic mechanisms of microglial-mediated neuroprotection, mainly for the identification of potentially effective neuroprotective molecules, and to design new approaches in a gene therapy set-up. Microglia could act as both a target and a vehicle for CNS gene delivery of neuroprotective factors, endogenously produced by microglia in physiological conditions, thus strengthening the microglial neuroprotective phenotype, even in a pathological situation.
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Increased binding of peripheral benzodiazepine receptor in Alzheimer's disease measured by positron emission tomography with [11C]DAA1106. Biol Psychiatry 2008; 64:835-41. [PMID: 18514164 DOI: 10.1016/j.biopsych.2008.04.021] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2007] [Revised: 04/19/2008] [Accepted: 04/21/2008] [Indexed: 12/27/2022]
Abstract
BACKGROUND Peripheral benzodiazepine receptor (PBR) in the brain of Alzheimer's disease (AD) patients has been discussed in relation to the role of gliosis in AD. The PBR was shown to have the ability to reflect activated glial cells, including microglia. The role of activated microglia in AD is an important topic in the pathophysiology of AD. The aim of this study was to quantify PBR in AD brain with a new high-sensitive PBR ligand, [(11)C]DAA1106. METHODS Positron emission tomography (PET) scans with [(11)C]DAA1106, a potent and selective ligand for PBR, were performed on 10 patients with AD and 10 age-matched control subjects. All patients had mild to moderate dementia. Duration of illness was 1-3 years at the time of the scans. The PBR binding in the regions of interest was quantified by binding potential (BP) obtained from compartmental model analysis with plasma input function. RESULTS Mean BP was increased in the brain of AD patients compared with control subjects in all measured regions. Statistical significance reached across many of the regions examined, including dorsal and medial prefrontal cortex, lateral temporal cortex, parietal cortex, occipital cortex, anterior cingulate cortex, striatum, and cerebellum. CONCLUSIONS The broad increase of PBR binding measured with [(11)C]DAA1106 in the brain of AD patients suggests a widespread existence of cellular reactions with PBR in relatively early-stage AD.
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Mastrangelo MA, Bowers WJ. Detailed immunohistochemical characterization of temporal and spatial progression of Alzheimer's disease-related pathologies in male triple-transgenic mice. BMC Neurosci 2008; 9:81. [PMID: 18700006 PMCID: PMC2527610 DOI: 10.1186/1471-2202-9-81] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Accepted: 08/12/2008] [Indexed: 01/20/2023] Open
Abstract
Background Several transgenic animal models genetically predisposed to develop Alzheimer's disease (AD)-like pathology have been engineered to facilitate the study of disease pathophysiology and the vetting of potential disease-modifying therapeutics. The triple transgenic mouse model of AD (3xTg-AD) harbors three AD-related genetic loci: human PS1M146V, human APPswe, and human tauP301L. These mice develop both amyloid plaques and neurofibrillary tangle-like pathology in a progressive and age-dependent manner, while these pathological hallmarks are predominantly restricted to the hippocampus, amygdala, and the cerebral cortex the main foci of AD neuropathology in humans. This model represents, at present, one of the most advanced preclinical tools available and is being employed ever increasingly in the study of mechanisms underlying AD, yet a detailed regional and temporal assessment of the subtleties of disease-related pathologies has not been reported. Methods and results In this study, we immunohistochemically documented the evolution of AD-related transgene expression, amyloid deposition, tau phosphorylation, astrogliosis, and microglial activation throughout the hippocampus, entorhinal cortex, primary motor cortex, and amygdala over a 26-month period in male 3xTg-AD mice. Intracellular amyloid-beta accumulation is detectable the earliest of AD-related pathologies, followed temporally by phospho-tau, extracellular amyloid-beta, and finally paired helical filament pathology. Pathology appears to be most severe in medial and caudal hippocampus. While astrocytic staining remains relatively constant at all ages and regions assessed, microglial activation appears to progressively increase temporally, especially within the hippocampal formation. Conclusion These data fulfill an unmet need in the ever-widening community of investigators studying 3xTg-AD mice and provide a foundation upon which to design future experiments that seek to examine stage-specific disease mechanisms and/or novel therapeutic interventions for AD.
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Affiliation(s)
- Michael A Mastrangelo
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642, USA.
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Apolipoprotein E, amyloid-beta, and blood-brain barrier permeability in Alzheimer disease. J Neuropathol Exp Neurol 2008; 67:261-70. [PMID: 18379441 DOI: 10.1097/nen.0b013e31816a0dc8] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
There is increasing evidence for blood-brain barrier (BBB) compromise in Alzheimer disease (AD). The presence of the epsilon4 allele of the apolipoprotein E (apoE) gene is a risk factor for sporadic AD. Apolipoprotein E is essential both for maintenance of BBB integrity and for the deposition of fibrillar amyloid-beta (Abeta) that leads to the development of Abeta plaques in AD and to cerebral amyloid angiopathy. This review investigates the relationships between apoE, Abeta, and the BBB in AD. Alterations in the expression and distribution of the BBB Abeta transporters receptor for advanced glycation end-products and low-density lipoprotein receptor-related protein 1 in AD and the potential roles of apoE4 expression in adversely influencing Abeta burden and BBB permeability are also examined. Because both apoE and Abeta are ligands for low-density lipoprotein receptor-related protein 1, all 3 molecules are present in AD plaques, and most AD plaques are located close to the cerebral microvasculature. The interactions of these molecules at the BBB likely influence metabolism and clearance of Abeta and contribute to AD pathogenesis. Therapeutic alternatives targeting apoE/Abeta and sealing a compromised BBB are under development for the treatment of AD.
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Appelt DM, Roupas MR, Way DS, Bell MG, Albert EV, Hammond CJ, Balin BJ. Inhibition of apoptosis in neuronal cells infected with Chlamydophila (Chlamydia) pneumoniae. BMC Neurosci 2008; 9:13. [PMID: 18218130 PMCID: PMC2266938 DOI: 10.1186/1471-2202-9-13] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Accepted: 01/24/2008] [Indexed: 12/29/2022] Open
Abstract
Background Chlamydophila (Chlamydia) pneumoniae is an intracellular bacterium that has been identified within cells in areas of neuropathology found in Alzheimer disease (AD), including endothelia, glia, and neurons. Depending on the cell type of the host, infection by C. pneumoniae has been shown to influence apoptotic pathways in both pro- and anti-apoptotic fashions. We have hypothesized that persistent chlamydial infection of neurons may be an important mediator of the characteristic neuropathology observed in AD brains. Chronic and/or persistent infection of neuronal cells with C. pneumoniae in the AD brain may affect apoptosis in cells containing chlamydial inclusions. Results SK-N-MC neuroblastoma cells were infected with the respiratory strain of C. pneumoniae, AR39 at an MOI of 1. Following infection, the cells were either untreated or treated with staurosporine and then examined for apoptosis by labeling for nuclear fragmentation, caspase activity, and membrane inversion as indicated by annexin V staining. C. pneumoniae infection was maintained through 10 days post-infection. At 3 and 10 days post-infection, the infected cell cultures appeared to inhibit or were resistant to the apoptotic process when induced by staurosporine. This inhibition was demonstrated quantitatively by nuclear profile counts and caspase 3/7 activity measurements. Conclusion These data suggest that C. pneumoniae can sustain a chronic infection in neuronal cells by interfering with apoptosis, which may contribute to chronic inflammation in the AD brain.
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Affiliation(s)
- Denah M Appelt
- Department of Neuroscience, Physiology & Pharmacology, Philadelphia College of Osteopathic Medicine, Philadelphia, USA.
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Fiala JC. Mechanisms of amyloid plaque pathogenesis. Acta Neuropathol 2007; 114:551-71. [PMID: 17805553 DOI: 10.1007/s00401-007-0284-8] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Revised: 08/12/2007] [Accepted: 08/13/2007] [Indexed: 12/25/2022]
Abstract
The first ultrastructural investigations of Alzheimer's disease noted the prominence of degenerating mitochondria in the dystrophic neurites of amyloid plaques, and speculated that this degeneration might be a major contributor to plaque pathogenesis. However, the fate of these organelles has received scant consideration in the intervening decades. A number of hypotheses for the formation and progression of amyloid plaques have since been suggested, including glial secretion of amyloid, somal and synaptic secretion of amyloid-beta protein from neurons, and endosomal-lysosomal aggregation of amyloid-beta protein in the cell bodies of neurons, but none of these hypotheses fully account for the focal accumulation of amyloid in plaques. In addition to Alzheimer's disease, amyloid plaques occur in a variety of conditions, and these conditions are all accompanied by dystrophic neurites characteristic of disrupted axonal transport. The disruption of axonal transport results in the autophagocytosis of mitochondria without normal lysosomal degradation, and recent evidence from aging, traumatic injury, Alzheimer's disease and transgenic mice models of Alzheimer's disease, suggests that the degeneration of these autophagosomes may lead to amyloid production within dystrophic neurites. The theory of amyloid plaque pathogenesis has thus come full circle, back to the intuitions of the very first researchers in the field.
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Affiliation(s)
- John C Fiala
- Department of Health Sciences, Boston University, Boston, MA 02215, USA.
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Hodgkinson GN, Tresco PA, Hlady V. The differential influence of colocalized and segregated dual protein signals on neurite outgrowth on surfaces. Biomaterials 2007; 28:2590-602. [PMID: 17316787 PMCID: PMC1892536 DOI: 10.1016/j.biomaterials.2007.01.038] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Accepted: 01/23/2007] [Indexed: 12/01/2022]
Abstract
We present an in vitro micropatterning approach in which the density and spatial presentation of two separate protein layers can be independently controlled to form cell stripe assays through (1) the simultaneous application of microcontact printing (microCP) and microfluidic network (microFN) patterning to generate alternating stripes of pure single protein layers or (2) through microCP onto a pre-adsorbed homogeneous protein layer to generate alternating single and dual protein stripes. This approach enabled the creation of choice boundaries in which protein-protein interactions were limited and the effects of spatially segregated or colocalized dual protein signals on model primary neuronal behavior could be readily interrogated and compared on both glass and tissue culture polystyrene substrates. Dorsal root ganglion (DRG) cell body attachment was dictated largely by non-specific cell adhesion interactions and interactions between the guidance molecules laminin and aggrecan were insufficient to explain aggrecan inhibition on neurite outgrowth. The presentation of a specific laminin epitope stabilized by interactions with aggrecan and destabilized by microCP was a strong predictor of neurite promoting activity. These observations provide evidence that aggrecan is intrinsically inhibitory and that laminin-aggrecan interactions do not diminish laminin growth promoting properties.
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Affiliation(s)
- Gerald N. Hodgkinson
- Department of Bioengineering, University of Utah, 20 S. 2030 E., Rm. 108, Salt Lake City, Utah 84112
| | - Patrick A. Tresco
- Department of Bioengineering, University of Utah, 20 S. 2030 E., Rm. 108, Salt Lake City, Utah 84112
- Keck Center for Tissue Engineering, University of Utah, 20 S. 2030 E., Rm. 108, Salt Lake City, Utah 84112
| | - Vladimir Hlady
- Department of Bioengineering, University of Utah, 20 S. 2030 E., Rm. 108, Salt Lake City, Utah 84112
- * Corresponding author. Tel.: 801-581-5042; E-mail address:
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Donahue JE, Flaherty SL, Johanson CE, Duncan JA, Silverberg GD, Miller MC, Tavares R, Yang W, Wu Q, Sabo E, Hovanesian V, Stopa EG. RAGE, LRP-1, and amyloid-beta protein in Alzheimer's disease. Acta Neuropathol 2006; 112:405-15. [PMID: 16865397 DOI: 10.1007/s00401-006-0115-3] [Citation(s) in RCA: 350] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 06/30/2006] [Accepted: 07/01/2006] [Indexed: 11/28/2022]
Abstract
The receptor for advanced glycation end products (RAGE) is thought to be a primary transporter of beta-amyloid across the blood-brain barrier (BBB) into the brain from the systemic circulation, while the low-density lipoprotein receptor-related protein (LRP)-1 mediates transport of beta-amyloid out of the brain. To determine whether there are Alzheimer's disease (AD)-related changes in these BBB-associated beta-amyloid receptors, we studied RAGE, LRP-1, and beta-amyloid in human elderly control and AD hippocampi. In control hippocampi, there was robust RAGE immunoreactivity in neurons, whereas microvascular staining was barely detectable. LRP-1 staining, in contrast, was clearly evident within microvessels but only weakly stained neurons. In AD cases, neuronal RAGE immunoreactivity was significantly decreased. An unexpected finding was the strongly positive microvascular RAGE immunoreactivity. No evidence for colocalization of RAGE and beta-amyloid was seen within either microvessels or senile plaques. A reversed pattern was evident for LRP-1 in AD. There was very strong staining for LRP-1 in neurons, with minimal microvascular staining. Unlike RAGE, colocalization of LRP-1 and beta-amyloid was clearly present within senile plaques but not microvessels. Western blot analysis revealed a much higher concentration of RAGE protein in AD hippocampi as compared with controls. Concentration of LRP-1 was increased in AD hippocampi, likely secondary to its colocalization with senile plaques. These data confirm that AD is associated with changes in the relative distribution of RAGE and LRP-1 receptors in human hippocampus. They also suggest that the proportion of amyloid within the brains of AD patients that is derived from the systemic circulation may be significant.
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Affiliation(s)
- John E Donahue
- Department of Clinical Neurosciences, Rhode Island Hospital and Brown Medical School, Providence, RI 02903, USA.
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Carty NC, Wilcock DM, Rosenthal A, Grimm J, Pons J, Ronan V, Gottschall PE, Gordon MN, Morgan D. Intracranial administration of deglycosylated C-terminal-specific anti-Abeta antibody efficiently clears amyloid plaques without activating microglia in amyloid-depositing transgenic mice. J Neuroinflammation 2006; 3:11. [PMID: 16686956 PMCID: PMC1479322 DOI: 10.1186/1742-2094-3-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2006] [Accepted: 05/10/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Antibodies against the Ass peptide clear Ass deposits when injected intracranially. Deglycosylated antibodies have reduced effector functions compared to their intact counterparts, potentially avoiding immune activation. METHODS Deglycosylated or intact C-terminal specific high affinity anti-Abeta antibody (2H6) were intracranially injected into the right frontal cortex and hippocampus of amyloid precursor protein (APP) transgenic mice. The untreated left hemisphere was used to normalize for the extent of amyloid deposition present in each mouse. Control transgenic mice were injected with an antibody against a drosophila-specific protein (amnesiac). Tissues were examined for brain amyloid deposition and microglial responses 3 days after the injection. RESULTS The deglycosylated 2H6 antibody had lower affinity for several murine Fcgamma receptors and human complement than intact 2H6 without a change in affinity for Ass. Immunohistochemistry for Abeta and thioflavine-S staining revealed that both diffuse and compact deposits were reduced by both antibodies. In animals treated with the intact 2H6 antibody, a significant increase in Fcgamma-receptor II/III immunostaining was observed compared to animals treated with the control IgG antibody. No increase in Fcgamma-receptor II/III was found with the deglycosylated 2H6 antibody. Immunostaining for the microglial activation marker CD45 demonstrated a similar trend. CONCLUSION These findings suggest that the deglycosylated 2H6 is capable of removing both compact and diffuse plaques without activating microglia. Thus, antibodies with reduced effector functions may clear amyloid without concomitant immune activation when tested as immunotherapy for Alzheimer's disease.
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Affiliation(s)
- Niki C Carty
- Alzheimer's Research Laboratory, University of South Florida, Department of Molecular Pharmacology and Physiology, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA
| | - Donna M Wilcock
- Alzheimer's Research Laboratory, University of South Florida, Department of Molecular Pharmacology and Physiology, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA
| | - Arnon Rosenthal
- Rinat Neuroscience Corp. 3155 Porter Drive, Palo Alto, California, 94304, USA
| | - Jan Grimm
- Rinat Neuroscience Corp. 3155 Porter Drive, Palo Alto, California, 94304, USA
| | - Jaume Pons
- Rinat Neuroscience Corp. 3155 Porter Drive, Palo Alto, California, 94304, USA
| | - Victoria Ronan
- Alzheimer's Research Laboratory, University of South Florida, Department of Molecular Pharmacology and Physiology, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA
| | - Paul E Gottschall
- Alzheimer's Research Laboratory, University of South Florida, Department of Molecular Pharmacology and Physiology, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA
| | - Marcia N Gordon
- Alzheimer's Research Laboratory, University of South Florida, Department of Molecular Pharmacology and Physiology, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA
| | - Dave Morgan
- Alzheimer's Research Laboratory, University of South Florida, Department of Molecular Pharmacology and Physiology, 12901 Bruce B Downs Blvd, Tampa, FL 33612, USA
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Gaudreault SB, Blain JF, Gratton JP, Poirier J. A role for caveolin-1 in post-injury reactive neuronal plasticity. J Neurochem 2005; 92:831-9. [PMID: 15686485 DOI: 10.1111/j.1471-4159.2004.02917.x] [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] [Indexed: 11/28/2022]
Abstract
Remodeling and plasticity in the adult brain require cholesterol redistribution and synthesis for the formation of new membrane components. Caveolin-1 is a cholesterol-binding membrane protein involved in cellular cholesterol transport and homeostasis. Evidence presented here demonstrates an up-regulation of caveolin-1 in the hippocampus, which was temporally correlated with an increase in synaptophysin during the reinnervation phase in a mouse model of hippocampal deafferentation. Using an in vitro model of neuronal reactive plasticity, we examined the effect of virally mediated overexpression of caveolin-1 on injured differentiated PC12 cells undergoing terminal remodeling. Three days post lesion, caveolin-1-overexpressing cells revealed increases in synaptophysin and GAP-43, two markers of neurite sprouting and synaptogenesis. Morphologically, caveolin-1-overexpressing cells showed a decrease in primary neurite outgrowth and branching as well as an increase in neurite density. Caveolin-1-overexpressing cells also revealed the presence of terminal swelling and beading along processes, consistent with a possible alteration of microtubules stability. Moreover, a focal enrichment of caveolin-1 immunofluorescence was observed at the bases of axonal and dendritic terminals of mouse primary hippocampal neurons. Altogether, these results indicate that caveolin-1 plays an active role in the regulation of injury-induced synaptic and terminal remodeling in the adult CNS.
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Affiliation(s)
- Sophie B Gaudreault
- Douglas Hospital Research Center, Neurological Sciences Department, McGill University, Montreal, Canada
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Adlard PA, Cummings BJ. Alzheimer’s disease—a sum greater than its parts? Neurobiol Aging 2004; 25:725-33; discussion 743-6. [PMID: 15165695 DOI: 10.1016/j.neurobiolaging.2003.12.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Accepted: 12/10/2003] [Indexed: 10/26/2022]
Affiliation(s)
- Paul A Adlard
- Institute for Brain Aging and Dementia, University of California, 1113 Gillespie N.R.F., Irvine, CA 92697-4540, USA.
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Hashimoto M, Masliah E. Cycles of aberrant synaptic sprouting and neurodegeneration in Alzheimer's and dementia with Lewy bodies. Neurochem Res 2004; 28:1743-56. [PMID: 14584828 DOI: 10.1023/a:1026073324672] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) are the most common neurodegenerative disorders affecting the elderly. The cognitive and motor deficits in these diseases are associated with the disruption of neuritic substructure, loss of synaptic contacts in selectively vulnerable circuitries, and aberrant sprouting. Where as in AD, accumulation of misfolded forms of Abeta triggers neurodegeneration, in DLB accumulation of alpha-synuclein might play a central role. The mechanisms by which oligomeric forms of these proteins might lead to cycles of synapse loss and aberrant sprouting are currently under investigation. Several possibilities are being considered, including mitochondrial damage, caspase activation, lysosomal leakage, fragmentation of the Golgi apparatus, interference with synaptic vesicle transport and function, and interference with gene transcription and signaling. Among them, recent lines of research support the possibility that alterations in signaling pathways such extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 relevant to synaptic plasticity and cell survival might play a pivotal role. A wide range of cellular functions are affected by the accumulation of misfolded Abeta and alpha-synuclein; thus it is possible that a more fundamental cellular alteration may underlie the mechanisms of synaptic pathology in these disorders. Among them, one possibility is that scaffold proteins, such as caveolin and JNK-interacting protein (JIP), which are necessary to integrate signaling pathways, are affected, leading to cycles of synapse loss and aberrant sprouting. This is significant because both caveolar dysfunction and altered axonal plasticity might be universally important in the pathogenesis of various neurodegenerative disorders, and therefore these signaling pathways might be common therapeutic targets for these devastating diseases.
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Affiliation(s)
- Makoto Hashimoto
- Department of Neurosciences. University of California, San Diego, La Jolla, California 92093-0624, USA
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36
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Blanchard V, Moussaoui S, Czech C, Touchet N, Bonici B, Planche M, Canton T, Jedidi I, Gohin M, Wirths O, Bayer TA, Langui D, Duyckaerts C, Tremp G, Pradier L. Time sequence of maturation of dystrophic neurites associated with Abeta deposits in APP/PS1 transgenic mice. Exp Neurol 2004; 184:247-63. [PMID: 14637096 DOI: 10.1016/s0014-4886(03)00252-8] [Citation(s) in RCA: 227] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Several novel transgenic mouse models expressing different mutant APPs in combination with mutant PS1 have been developed. These models have been analyzed to investigate the formation and progressive alterations of dystrophic neurites (DNs) in relation to Abeta deposits. In the most aggressive model, Abeta deposits appear as early as 2.5 months of age. Maturation of DNs was qualitatively quite similar among models and in some respect reminiscent of human AD pathology. From the onset of deposition, most if not all Abeta deposits were decorated with a high number of APP-, ubiquitin-, and MnSOD-immunoreactive DNs. Phosphorylated Tau DNs, however, appeared at a much slower rate and were more restricted. Mitochondrial dysfunction markers were observed in DNs: the frequency and the density per deposit of DNs accumulating cytochrome c, cytochrome oxidase 1, and Bax progressively increased with age. Later, the burden of reactive DNs was reduced around large compact/mature deposits. In addition, the previously described phenomenon of early intraneuronal Abeta accumulation in our models was associated with altered expression of APP protein as well as oxidative and mitochondrial stress markers occasionally in individual neurons. The present study demonstrates that oxidative and mitochondrial stress factors are present at several phases of Abeta pathology progression, confirming the neuronal dysfunction in APP transgenic mice.
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Affiliation(s)
- Véronique Blanchard
- Neurodegenerative Disease Group, Centre de Recherche de Paris, Aventis Pharma 94403, Vitry sur Seine Cedex, France.
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37
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Nishimura I, Takazaki R, Kuwako KI, Enokido Y, Yoshikawa K. Upregulation and antiapoptotic role of endogenous Alzheimer amyloid precursor protein in dorsal root ganglion neurons. Exp Cell Res 2003; 286:241-51. [PMID: 12749853 DOI: 10.1016/s0014-4827(03)00066-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The amyloid precursor protein (APP) is a transmembrane protein whose abnormal processing is associated with the pathogenesis of Alzheimer's disease. In this study, we examined the expression and role of cell-associated APP in primary dorsal root ganglion (DRG) neurons. When dissociated DRG cells prepared from mouse embryos were treated with nerve growth factor (NGF), neuronal APP levels were transiently elevated. DRG neurons treated with an antibody against cell surface APP failed to mature and underwent apoptosis. When NGF was withdrawn from the cultures after a 36-h NGF treatment, virtually all neurons underwent apoptosis by 48 h. During the course of apoptosis, some neurons with intact morphology contained increased levels of APP immunoreactivity, whereas the APP levels were greatly reduced in apoptotic neurons. Furthermore, affected neurons contained immunoreactivities for activated caspase-3, a caspase-cleaved APP fragment (APPDeltaC31), and Abeta. Downregulation of endogenous APP expression by treatment with an APP antisense oligodeoxynucleotide significantly increased the number of apoptotic neurons in NGF-deprived DRG cultures. Furthermore, overexpression of APP by adenovirus vector-mediated gene transfer reduced the number of apoptotic neurons deprived of NGF. These results suggest that endogenous APP is upregulated to exert an antiapoptotic effect on neurotrophin-deprived DRG neurons and subsequently undergoes caspase-dependent proteolysis.
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Affiliation(s)
- Isao Nishimura
- Division of Regulation of Macromolecular Functions, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan
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38
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Kuwako KI, Nishimura I, Uetsuki T, Saido TC, Yoshikawa K. Activation of calpain in cultured neurons overexpressing Alzheimer amyloid precursor protein. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 107:166-75. [PMID: 12425945 DOI: 10.1016/s0169-328x(02)00489-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
We have previously reported that overexpression of wild-type amyloid precursor protein (APP) in postmitotic neurons induces cleavage-dependent activation of caspase-3 both in vivo and in vitro. In this study, we investigated the mechanism underlying APP-induced caspase-3 activation using adenovirus-mediated gene transfer into postmitotic neurons derived from human embryonal carcinoma NT2 cells. Overexpression of wild-type APP significantly increased intracellular (45)Ca(2+) content prior to the activation of caspase-3 in NT2-derived neurons. Chelation of intracellular Ca(2+) markedly suppressed APP-induced activation of caspase-3. Furthermore, calpain, a Ca(2+)-dependent cysteine protease, was activated in neurons overexpressing APP as assessed by increased levels of calpain-cleaved alpha-fodrin and autolytic mu-calpain fragments. Neither calpain nor caspase-3 was activated in neurons expressing an APP mutant defective in the Abeta(1-20) domain. Calpain inhibitors almost completely suppressed APP-induced activation of neuronal caspase-3. E64d, a membrane permeable inhibitor of calpain, significantly suppressed APP-induced neuronal death. These results suggest that overexpression of wild-type APP activates calpain that mediates caspase-3 activation in postmitotic neurons.
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Affiliation(s)
- Ken-ichiro Kuwako
- Division of Regulation of Macromolecular Functions, Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan
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39
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Van Nostrand WE, Melchor JP, Keane DM, Saporito-Irwin SM, Romanov G, Davis J, Xu F. Localization of a fibrillar amyloid beta-protein binding domain on its precursor. J Biol Chem 2002; 277:36392-8. [PMID: 12107175 DOI: 10.1074/jbc.m204676200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Deposition of fibrillar amyloid-beta protein (Abeta) in senile plaques and in the walls of cerebral blood vessels is a key pathological feature of Alzheimer's disease and certain related disorders. Fibrillar Abeta deposition is intimately associated with neuronal and cerebrovascular cell death both in vivo and in vitro. Similarly, accumulation of the Abeta protein precursor (AbetaPP) is also observed at sites of fibrillar Abeta deposition. Recently, we reported that fibrillar Abeta, but not unassembled Abeta, promotes the specific binding of AbetaPP through its cysteine-rich, amino-terminal region (Melchor, J. P., and Van Nostrand, W. E. (2000) J. Biol. Chem. 275, 9782-9791). In the present study we sought to determine the precise site on AbetaPP that facilitates its binding to fibrillar Abeta. A series of synthesized overlapping peptides spanning the cysteine-rich, amino-terminal region of AbetaPP were used as competitors for AbetaPP binding to fibrillar Abeta. A peptide spanning residues 105-119 of AbetaPP competitively inhibited AbetaPP binding to fibrillar Abeta in a solid-phase binding assay and on the surface of cultured human cerebrovascular smooth muscle cells. Alanine-scanning mutagenesis of residues 105-117 within glutathione S-transferase (GST)-AbetaPP-(18-119) revealed that His(110), Val(112), and Ile(113) are key residues that facilitate AbetaPP binding to fibrillar Abeta. These specific residues belong to a common beta-strand within this region of AbetaPP. Wild-type GST-AbetaPP-(18-119) protected cultured human cerebrovascular smooth muscle cells from Abeta-induced toxicity whereas H110A mutant GST-AbetaPP-(18-119) did not. Wild-type GST-AbetaPP-(18-119) bound to different isoforms of fibrillar Abeta and fibrillar amylin peptides whereas H110A mutant and I113A mutant GST-AbetaPP-(18-119) were substantially less efficient binding to each fibrillar peptide. We conclude that His(110), Val(112), and Ile(113), residing in a common beta-strand region within AbetaPP-(18-119), comprise a domain that mediates the binding of AbetaPP to fibrillar peptides.
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Affiliation(s)
- William E Van Nostrand
- Department of Medicine, Health Sciences Center, Stony Brook University, Stony Brook, New York 11794-8153, USA.
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40
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Cummings BJ, Mason AJL, Kim RC, Sheu PCY, Anderson AJ. Optimization of techniques for the maximal detection and quantification of Alzheimer's-related neuropathology with digital imaging. Neurobiol Aging 2002; 23:161-70. [PMID: 11804699 DOI: 10.1016/s0197-4580(01)00316-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Prior to undertaking quantitative neuropathological studies of Alzheimer's disease, methods for detecting plaques and tangles must be optimized. While suitable antibodies have been developed with great sensitivity, specificity, and reliability, there is no standard pre-treatment protocol for key AD-related pathology. It is well known that formic acid treatment enhances the detection of beta-amyloid. But what concentration of formic acid is best; can similar methods enhance the detection of tau-related pathology? This study compared multiple antigen retrieval techniques (e.g. boiling in citrate or glycine buffer, microwaves, formic acid concentrations), to develop an optimal, standardized protocol for quantitative digital microscopy. Free-floating (40 microm) and paraffin-embedded (12 microm) sections of formalin fixed frontal cortex from mild, moderate, and severe AD cases (n = 18) were pretreated with fifteen different protocols and stained with each of the following antibodies: beta42, PHF-1, MC-1 and AT8. Random fields were digitally captured and images were thresholded to select for positively stained areas versus background (e.g. "load"). As previously reported, high concentrations of formic acid were extremely effective in enhancing the detection of beta-amyloid; as much as a 2-fold enhancement in Abeta "load" values were observed. Surprisingly, tau-related pathology detection also increased significantly following pretreatment. Depending on the antibody, between a 3-fold and 6-fold enhancement was possible relative to no pretreatment. Comparable results were found in paraffin-embedded sections. Similar enhancements in the detection of pathology were obtained following 99% formic acid exposure, microwaving in citrate buffer (pH 9.0) or exposure to 99% formic acid then boiling in citrate buffer (pH 6.0). Because the latter treatments were often harsh on the tissue and more difficult to control, we recommend a standard tissue pretreatment of 99% formic acid for seven minutes for both beta-amyloid and tau-related pathology.
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Affiliation(s)
- Brian J Cummings
- Institute for Brain Aging, University of California, Irvine, CA 92697-4540, USA
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41
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Nishimura I, Uetsuki T, Kuwako K, Hara T, Kawakami T, Aimoto S, Yoshikawa K. Cell death induced by a caspase-cleaved transmembrane fragment of the Alzheimer amyloid precursor protein. Cell Death Differ 2002; 9:199-208. [PMID: 11840170 DOI: 10.1038/sj.cdd.4400931] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2001] [Revised: 06/18/2001] [Accepted: 07/13/2001] [Indexed: 12/24/2022] Open
Abstract
The Alzheimer amyloid precursor protein (APP) is a transmembrane protein whose abnormal processing is associated with the pathogenesis of Alzheimer's disease. Activated caspases cleave APP and generate its carboxyl-terminally truncated fragment (APPdeltaC31). We have previously reported that overexpression of wild-type APP induces caspase-3 activation and apoptosis in postmitotic neurons. We now report that APPdeltaC31 potentially plays pathophysiological roles in neuronal death. Adenovirus-mediated overexpression of wild-type APP695 induced activation of caspase-3 and accumulation of APPdeltaC31 in postmitotic neurons derived from human NT2 embryonal carcinoma cells, whereas an APP mutant lacking the Abeta(1-20) region induced neither caspase-3 activation nor APPdeltaC31 generation. Inhibition of caspase-3 suppressed the generation of APPdeltaC31 in APP-overexpressing neurons. Forced expression of APPdeltaC31 induced apoptotic changes of neurons and non-neuronal cells, but failed to activate caspase-3. The cytotoxicity of APPdeltaC31 was also dependent on the Abeta(1-20) region. These results suggest that accumulation of wild-type APP activates neuronal caspase-3 to generate APPdeltaC31 that mediates caspase-3-independent cell death.
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Affiliation(s)
- I Nishimura
- Division of Regulation of Macromolecular Functions, Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, Osaka 565-0871, Japan
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42
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Lee MJ, Oh JY, Park HT, Uhlinger DJ, Kwak JY. Enhancement of phospholipase D activity by overexpression of amyloid precursor protein in P19 mouse embryonic carcinoma cells. Neurosci Lett 2001; 315:159-63. [PMID: 11716987 DOI: 10.1016/s0304-3940(01)02339-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It has been shown that phospholipase D (PLD) activity is stimulated by the beta-amyloid protein in neuronal cells. The aim of this study was to determine whether overexpression of the amyloid precursor protein (APP) affects the activity and the level of PLD expression in P19 embryonic carcinoma cells. We observed that the unstimulated basal PLD activity was higher in wild-type APP(695)-transfected cells than in non-transfected control cells. The protein kinase C (PKC) activator, phorbol 12-myristate 13-acetate (PMA), has been shown to activate PLD. PMA-stimulated PLD activity was 3-fold higher in the APP overexpressing cells than in the control cells. P19 cells express two distinct PLD isozymes, PLD1 and PLD2. The level of PLD2 expression was increased by APP overexpression. Although the PKC inhibitor, GF109203X, inhibited PMA-stimulated PLD activity, it did not affect the high basal PLD activity induced by APP overexpression. Neuronal differentiation of the P19 cells by retinoic acid did not affect the basal or PMA stimulated-PLD activity. Interestingly, APP overexpression in the differentiated P19 cells also led to an increase in PLD activity. The PLD activity of the P19 cells is apparently regulated by amyloid protein through both PKC-dependent and -independent mechanisms.
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Affiliation(s)
- M J Lee
- Department of Biochemistry, Dong-A University College of Medicine and Dong-A University Institute of Medical Science, Seo-Ku, Pusan 602-103, South Korea
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43
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Snow DM, Mullins N, Hynds DL. Nervous system-derived chondroitin sulfate proteoglycans regulate growth cone morphology and inhibit neurite outgrowth: a light, epifluorescence, and electron microscopy study. Microsc Res Tech 2001; 54:273-86. [PMID: 11514984 DOI: 10.1002/jemt.1140] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Proteoglycans influence aging and plasticity in the nervous system. Particularly prominent are the chondroitin sulfate proteoglycans (CSPGs), which are generally inhibitory to neurite outgrowth. During development, CSPGs facilitate normal guidance, but following nervous system injury and in diseases of aging (e.g., Alzheimer's disease), they block successful regeneration, and are associated with axon devoid regions and degenerating nerve cells. Whereas previous studies used non-nervous system sources of CSPGs, this study analyzed the morphology and behavior of sensory (dorsal root ganglia) neurons, and a human nerve cell model (SH-SY5Y neuroblastoma cells) as they contacted nervous system-derived CSPGs, using a variety of microscopy techniques. The results of these qualitative analyses show that growth cones of both nerve cell types contact CSPGs via actin-based filopodia, sample the CSPGs repeatedly without collapse, and alter their trajectory to avoid nervous system-derived CSPGs. Turning and branching are correlated with increased filopodial sampling, and are common to both neurons and Schwann cells. We show that CSPG expression by rat CNS astrocytes in culture is correlated with sensory neuron avoidance. Further, we show for the first time the ultrastructure of sensory growth cones at a CSPG-laminin border and reveal details of growth cone and neurite organization at this choice point. This type of detailed analysis of the response of growth cones to nervous system-derived CSPGs may lead to an understanding of CSPG function following injury and in diseases of aging, where CSPGs are likely to contribute to aberrant neurite outgrowth, failed or reduced synaptic connectivity, and/or ineffective plasticity.
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Affiliation(s)
- D M Snow
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, Kentucky 40536-0298, USA.
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44
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Gitter BD, Boggs LN, May PC, Czilli DL, Carlson CD. Regulation of cytokine secretion and amyloid precursor protein processing by proinflammatory amyloid beta (A beta). Ann N Y Acad Sci 2001; 917:154-64. [PMID: 11268339 DOI: 10.1111/j.1749-6632.2000.tb05379.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neurodegenerative processes in Alzheimer's disease (AD) are thought to be driven, in part, by the deposition of amyloid beta (A beta), a 39-43-aminoacid peptide product resulting from an alternative cleavage of amyloid precursor protein (APP). In addition to its neurotoxic properties, A beta may influence neuropathology by stimulating glial cell cytokine and acute phase protein secretion in affected areas of the brain (e.g., cortex, hippocampus). Using an in vitro human astrocyte model (U-373 MG astrocytoma cells), the effects of A beta treatment on acute phase protein (APP and alpha-1-antichymotrypsin [alpha 1-ACT]) and interleukin-8 (IL-8) were examined. U-373 MG cells secreted increased levels of alpha 1-ACT and neurotrophic/neuroprotective alpha-cleaved APP (alpha APP) after exposure to interleukin-1 beta (IL-1 beta) for 24 hours. A beta treatment resulted in a similar, but modest increase in alpha 1-ACT secretion, a two- to threefold stimulation of IL-8 production, and, conversely, a profound reduction in the levels of secreted alpha APPs. A beta inhibited alpha APP secretion by U-373 MG cells in a concentration- and conformation-dependent manner. Moreover, the reduction in alpha APP secretion was accompanied by an increase in cell-associated APP. Another proinflammatory amyloidogenic peptide, human amylin, similarly affected APP processing in U-373 astrocytoma cells. These data suggest that A beta may contribute to Alzheimer's-associated neuropathology by lowering the production of neuroprotective/neurotrophic alpha APPs. Moreover, the concomitant increase in cell-associated APP may provide increased substrate for the generation of amyloidogenic peptides within astrocytes.
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Affiliation(s)
- B D Gitter
- Neuroscience Diseases Research Division, Lilly Research Laboratories, Eli Lilly and Co., Lilly Corporate Center, Indianapolis, Indiana 46285, USA.
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45
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Anderson AJ, Ruehl WW, Fleischmann LK, Stenstrom K, Entriken TL, Cummings BJ. DNA damage and apoptosis in the aged canine brain: relationship to Abeta deposition in the absence of neuritic pathology. Prog Neuropsychopharmacol Biol Psychiatry 2000; 24:787-99. [PMID: 11191713 DOI: 10.1016/s0278-5846(00)00106-8] [Citation(s) in RCA: 14] [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: 10/18/2022]
Abstract
1. In addition to beta-amyloid (Abeta) deposition and cytoskeletal neuropathology, both the Alzheimer's disease (AD) and Down's syndrome (DS) human brain exhibit marked evidence of DNA damage, however, it is difficult to separate events that occur in conjunction with neurofibrillary pathology versus Abeta pathology in these systems. 2. In contrast, the aged canine brain exhibits the accumulation of Abeta into diffuse deposits similar to those found in early AD and DS in the absence of neurofibrillary pathology. Furthermore, Abeta deposition in canine brain is correlated with cognitive deficits. 3. In order to test the hypothesis that TUNEL labeling for DNA damage in AD is not simply a consequence of agonal artifacts, postmortem artifacts, or neurofibrillary pathology, and may be directly related to Abeta deposition, we examined Abeta immunoreactivity, PHF-1 immunoreactivity, and TUNEL labeling in this animal model. 4. These experiments reveal a relationship between the amount of DNA damage detected by TUNEL labeling and levels of Abeta deposition. Further, in animals with no TUNEL labeling, we detected no Abeta immunoreactivity. 5. These data support the hypothesis that TUNEL labeling in AD ans DS is not a consequence of agonal artifact, postmortem artifact, or tau pathology, and may be directly related to Abeta deposition and perhaps AD pathogenesis.
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Affiliation(s)
- A J Anderson
- Institute for Brain Aging and Dementia, University of California, Irvine 92696-4540, USA
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46
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Activation of neuronal caspase-3 by intracellular accumulation of wild-type Alzheimer amyloid precursor protein. J Neurosci 1999. [PMID: 10436052 DOI: 10.1523/jneurosci.19-16-06955.1999] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Forced overexpression of wild-type Alzheimer amyloid precursor protein (APP) causes postmitotic neurons to degenerate. Caspase-3 (CPP32) is a principal cell death protease involved in neuronal apoptosis during physiological development and under pathological conditions. Here, we investigated whether APP overexpression activates caspase-3 in human postmitotic neurons using adenovirus-mediated gene transfer. When a recombinant adenovirus vector expressing human wild-type APP695 was infected in vitro into neurally differentiated embryonal carcinoma NT2 cells, only postmitotic neurons underwent severe degeneration. Before neurodegeneration, full-length APP- and Abeta-immunoreactive peptides were accumulated in infected neurons, and caspase-3-like protease activity was markedly elevated. Western blot analysis revealed that activated caspase-3 subunits were generated in APP-accumulating neurons. Such neuronal caspase-3 activation was undetectable in NT2 neurons infected with beta-galactosidase-expressing adenovirus. Addition of the caspase-3 inhibitor acetyl-Asp-Glu-Val-Asp-aldehyde to the culture medium significantly reduced the severity of degeneration exhibited by APP-overexpressing neurons. Immunocytochemical analyses revealed that some APP-accumulating neurons contained activated caspase-3 subunits and exhibited the characteristics of apoptosis, such as chromatin condensation and DNA fragmentation. Activation of caspase-3 was also observed in vivo in rat hippocampal neurons infected with the APP-expressing adenovirus. These results suggest that wild-type APP is an intrinsic activator of caspase-3-mediated death machinery in postmitotic neurons.
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47
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Yang AJ, Chandswangbhuvana D, Shu T, Henschen A, Glabe CG. Intracellular accumulation of insoluble, newly synthesized abetan-42 in amyloid precursor protein-transfected cells that have been treated with Abeta1-42. J Biol Chem 1999; 274:20650-6. [PMID: 10400697 DOI: 10.1074/jbc.274.29.20650] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Our early study indicates that intracellular Abeta1-42 aggregates are resistant to degradation and accumulate as an insoluble residue in lysosomes, where they alter the normal catabolism of amyloid precursor protein (APP) to cause the accumulation of insoluble APP and amyloidogenic fragments. In this study, we examined whether the addition of exogenous Abeta1-42 also leads to the accumulation of newly synthesized intracellular Abeta. Here we describe that newly synthesized Abeta, especially Abetan-42, is generated from metabolically labeled APP and accumulates in the insoluble fraction of cell lysates after Abeta1-42 treatment. These results suggest that intracellular Abeta may derive from a solid phase, intracellular pathway. In contrast to the pathway that primarily produces secreted Abeta1-40, the solid-phase intracellular pathway preferentially produces Abetan-42 with ragged amino termini. Biochemical studies and amino acid sequencing analyses indicate that these intracellular Abeta also share the same types of Abeta structures that accumulate in the brain of Alzheimer's disease patients, suggesting that a significant fraction of the amyloid deposits in Alzheimer's disease may arise by this solid-phase pathway.
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Affiliation(s)
- A J Yang
- Dementia Research Program, Nathan Kline Institute, Orangeburg, New York 10962, USA.
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48
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Berger-Sweeney J, McPhie DL, Arters JA, Greenan J, Oster-Granite ML, Neve RL. Impairments in learning and memory accompanied by neurodegeneration in mice transgenic for the carboxyl-terminus of the amyloid precursor protein. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 66:150-62. [PMID: 10095087 DOI: 10.1016/s0169-328x(99)00014-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In Alzheimer's disease (AD), a progressive decline of cognitive functions is accompanied by neuropathology that includes the degeneration of neurons and the deposition of amyloid in plaques and in the cerebrovasculature. We have proposed that a fragment of the Alzheimer amyloid precursor protein (APP) comprising the carboxyl-terminal 100 amino acids of this molecule (APP-C100) plays a crucial role in the neurodegeneration and subsequent cognitive decline in AD. To test this hypothesis, we performed behavioral analyses on transgenic mice expressing APP-C100 in the brain. The results revealed that homozygous APP-C100 transgenic mice were significantly impaired in cued, spatial and reversal performance of a Morris water maze task, that the degree of the impairment in the spatial learning was age-dependent, and that the homozygous mice displayed significantly more degeneration of neurons in Ammon's horn of the hippocampal formation than did heterozygous or control mice. Among the heterozygotes, females were relatively more impaired in their spatial learning than were males. These findings show that expression of APP-C100 in the brain can cause age-dependent cognitive impairments that are accompanied by hippocampal degeneration.
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Affiliation(s)
- J Berger-Sweeney
- Department of Biological Sciences, Wellesley College, Wellesley, MA 02181, USA
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49
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Cotman CW, Hailer NP, Pfister KK, Soltesz I, Schachner M. Cell adhesion molecules in neural plasticity and pathology: similar mechanisms, distinct organizations? Prog Neurobiol 1998; 55:659-69. [PMID: 9670224 DOI: 10.1016/s0301-0082(98)00025-2] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Brain plasticity and the mechanisms controlling plasticity are central to learning and memory as well as the recovery of function after brain injury. While it is clear that neurotrophic factors are one of the molecular classes that continue to regulate brain plasticity in the adult central nervous system (CNS), less appreciated but equally profound is the role of cell adhesion molecules (CAMs) in plasticity mechanisms such as long term potentiation, preservation of neurons and regeneration. Ironically, however, CAMs can also reorganize the extra-cellular space and cause disturbances that drive the development of brain pathology in conditions such as Alzheimer's disease and multiple sclerosis. Candidate molecules include the amyloid precursor protein which shares many properties of a classical CAM and beta-amyloid which can masquerade as a pseudo CAM. Beta-Amyloid serves as a nidus for the formation of senile plaques in Alzheimer's disease and like CAMs provides an environment for organizing neurotrophic factors and other CAMs. Inflammatory responses evolve in this environment and can initiate a vicious cycle of perpetuated neuronal damage that is medicated by microglia, complement and other factors. Certain CAMs may converge on common signal transduction pathways involving focal adhesion kinases. Thus a breakdown in the organization of key CAMs and activation of their signal transduction mechanisms may serve as a new principle for the generation of brain pathology.
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Affiliation(s)
- C W Cotman
- Institute of Brain Aging and Dementia, University of California, Irvine 92697-4550, USA.
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Sheetz MP, Pfister KK, Bulinski JC, Cotman CW. Mechanisms of trafficking in axons and dendrites: implications for development and neurodegeneration. Prog Neurobiol 1998; 55:577-94. [PMID: 9670219 DOI: 10.1016/s0301-0082(98)00021-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In the area of routing and sorting of dendritic traffic, the current phenomenological data beg questions about the cellular mechanisms utilized not only to transport material but also to modulate activity in a process, even apoptosis. To aid in formulating testable hypotheses, many plausible models are developed here and linked with some of the preliminary data that supports them. We first assume that in long dendrites the sorting of membranous proteins into transport vesicles also involves the linkage of motor proteins to the vesicles. Second, we assume that the cytoskeleton in dendrites is altered from the cytoskeleton in axons and the cell body. Viral glycoproteins, MAP2 and specific mRNA sorting into dendrites provide the simplest models for analyzing vesicular, cytoskeletal and RNA sorting. In the case of viral glycoproteins, initial sorting appears to occur at the Golgi but additional routing steps involve further complexities that could best be served by an additional sorting step at the junction of the cell body and the process. Transport of the specialized cytoskeletal proteins and specific mRNAs as well as vesicular material could be controlled by a similar gatekeeper at the mouth of a process. Studies of the microtubule-organelle motor complex, regulation of microtubule-based motility by microtubule-associated proteins, and slow axonal transport all provide insights into important aspects of the routing and sorting. These processes are in turn controlled by extracellular signals such as those generated by matrix molecules or their hydrolysis products in the case of amyloid precursor protein (APP). Routing and sorting mechanisms may be central to the development of Alzheimer's disease in view of evidence that APP processing is affected, transport is disturbed, and intracellular vesicles (early endosomes) hypertrophied. Further it is possible that routing mechanisms play a role in cell-cell interactions as, for example, the possibility that pathogenic/cellular stress signals may be passed along circuits transsynaptically.
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Affiliation(s)
- M P Sheetz
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
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