| 1. |
- Capetillo-Zarate, Estibaliz, et al.
(författare)
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High-Resolution 3D Reconstruction Reveals Intra-Synaptic Amyloid Fibrils
- 2011
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Ingår i: American Journal of Pathology. - : Elsevier BV. - 1525-2191 .- 0002-9440. ; 179:5, s. 2551-2558
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Tidskriftsartikel (refereegranskat)abstract
- beta-Amyloid (A beta) accumulation and aggregation are hallmarks of Alzheimer's disease (AD). High-resolution three-dimensional (HR-3D) volumetric imaging allows for better analysis of fluorescence confocal microscopy and 3D visualization of All pathology in brain. Early intraneuronal A beta pathology was studied in AD transgenic mouse brains by HR-3D volumetric imaging. To better visualize and analyze the development of A beta pathology, thioflavin S staining and immunofluorescence using antibodies against A beta, fibrillar A beta, and structural and synaptic neuronal proteins were performed in the brain tissue of Tg19959, wild-type, and Tg19959-YFP mice at different ages. Images obtained by confocal microscopy were reconstructed into three-dimensional volumetric datasets. Such volumetric imaging of CA1 hippocampus of AD transgenic mice showed intraneuronal onset of A beta 42 accumulation and fibrillization within cell bodies, neurites, and synapses before plaque formation. Notably, early fibrillar A beta was evident within individual synaptic compartments, where it was associated with abnormal morphology. In dendrites, increasing intraneuronal thioflavin S correlated with decreases in neurofilament marker SMI32. Fibrillar A beta aggregates could be seen piercing the cell membrane. These data support that A beta fibrillization begins within AD vulnerable neurons, leading to disruption of cytoarchitecture and degeneration of spines and neurites. Thus, HR-3D volumetric image analysis allows for better visualization of intraneuronal A beta pathology and provides new insights into plaque formation in AD. (Am J Pathol 2011, 170:2551-2558. DOI: 10.1016/j.ajpath.2011.07.045)
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| 2. |
- Capetillo-Zarate, Estibaliz, et al.
(författare)
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Intraneuronal A beta Accumulation, Amyloid Plaques, and Synapse Pathology in Alzheimer's Disease
- 2012
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Ingår i: Neurodegenerative Diseases. - : S. Karger AG. - 1660-2862 .- 1660-2854. ; 10:1-4, s. 56-59
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Tidskriftsartikel (refereegranskat)abstract
- Background: beta-Amyloid (A beta) plaques are a pathological hallmark of Alzheimer's disease (AD) and multiple lines of evidence have linked A beta with AD. However, synapse loss is known as the best pathological correlate of cognitive impairment in AD, and intraneuronal A beta accumulation has been shown to precede plaque pathology. The progression of A beta accumulation to synapse loss and plaque formation remains incomplete. The objective is to investigate the progression of intraneuronal A beta accumulation in the brain. Methods: To visualize and analyze the development of A beta pathology we perform immunohistochemistry and immunofluorescence microscopy using antibodies against different A beta conformations, synaptic proteins and structural neuronal proteins in brain tissue of AD transgenic mouse models. Results: Our results show the intraneuronal onset of A beta 42 accumulation in AD mouse brains with aging. We observe an inverse correlation of A beta and amyloid fibrils with structural proteins within neurites. Images reveal aggregated amyloid within selective pyramidal neurons, neurites and synapses in AD transgenic mice as plaques arise. Conclusion: The data support that A beta 42 accumulation and aggregation begin within AD-vulnerable neurons in the brain. Progressive intraneuronal A beta 42 aggregation disrupts the normal cytoarchitecture of neurites. Copyright (C) 2012 S. Karger AG, Basel
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| 3. |
- Dumont, Magali, et al.
(författare)
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Bezafibrate administration improves behavioral deficits and tau pathology in P301S mice
- 2012
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 21:23, s. 5091-5105
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Tidskriftsartikel (refereegranskat)abstract
- Peroxisome proliferator-activated receptors (PPARs) are ligand-mediated transcription factors, which control both lipid and energy metabolism and inflammation pathways. PPAR agonists are effective in the treatment of metabolic diseases and, more recently, neurodegenerative diseases, in which they show promising neuroprotective effects. We studied the effects of the pan-PPAR agonist bezafibrate on tau pathology, inflammation, lipid metabolism and behavior in transgenic mice with the P301S human tau mutation, which causes familial frontotemporal lobar degeneration. Bezafibrate treatment significantly decreased tau hyperphosphorylation using AT8 staining and the number of MC1-positive neurons. Bezafibrate treatment also diminished microglial activation and expression of both inducible nitric oxide synthase and cyclooxygenase 2. Additionally, the drug differentially affected the brain and brown fat lipidome of control and P301S mice, preventing lipid vacuoles in brown fat. These effects were associated with behavioral improvement, as evidenced by reduced hyperactivity and disinhibition in the P301S mice. Bezafibrate therefore exerts neuroprotective effects in a mouse model of tauopathy, as shown by decreased tau pathology and behavioral improvement. Since bezafibrate was given to the mice before tau pathology had developed, our data suggest that bezafibrate exerts a preventive effect on both tau pathology and its behavioral consequences. Bezafibrate is therefore a promising agent for the treatment of neurodegenerative diseases associated with tau pathology.
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| 4. |
- Gouras, Gunnar, et al.
(författare)
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Critical role of intraneuronal A beta in Alzheimer's disease: Technical challenges in studying intracellular A beta
- 2012
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Ingår i: Life Sciences. - : Elsevier BV. - 1879-0631 .- 0024-3205. ; 91:23-24, s. 1153-1158
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Multiple lines of evidence have implicated beta-amyloid (A beta) in the pathogenesis of Alzheimer's disease (AD). However, the mechanism(s) whereby A beta is involved in the disease process remains unclear. The dominant hypothesis in AD has been that A beta initiates the disease via toxicity from secreted, extracellular A beta aggregates. More recently, an alternative hypothesis has emerged focusing on a pool of A beta that accumulates early on within AD vulnerable neurons of the brain. Although the topic of intraneuronal A beta has been of major interest in the field, technical difficulties in detecting intraneuronal A beta have also made this topic remarkably controversial. Here we review evidence pointing to the critical role of intraneuronal A beta in AD and provide insights both into challenges faced in detecting intracellular A beta and the prion-like properties of A beta. Main methods: Immunoprecipitation and Western blot are used for A beta detection. Key findings: We highlight that a standard biochemical method can underestimate intraneuronal A beta and that extracellular A beta can up-regulate intracellular A beta. We also show that detergent can remove intraneuronal A beta. Significance: There is a growing awareness that intraneuronal A beta is a key pathogenic pool of A beta involved in causing synapse dysfunction. Difficulties in detecting intraneuronal A beta are an insufficient reason for ignoring this critical pool of A beta. (C) 2012 Elsevier Inc. All rights reserved.
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| 5. |
- Tampellini, Davide, et al.
(författare)
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Analysis of vesicular trafficking in primary neurons by live imaging.
- 2011
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Ingår i: Methods in Molecular Biology. - Totowa, NJ : Humana Press. - 1940-6029. ; 793, s. 343-350
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease, the most common neurodegenerative disease, is characterized by a progressive loss of synapses and accumulation of amyloid-beta (Aβ) peptides in the brain. Previous studies demonstrated that acute increase in synaptic activity in cultured hippocampal slices and mouse brains (Cirrito et al. Neuron 48: 913-922, 2005; Kamenetz et al. Neuron 37: 925-937, 2003) enhanced secretion of Aβ. Since synaptic activity promotes Aβ secretion, it could also affect the trafficking and processing of its precursor, the amyloid precursor protein (APP). Here, we describe a method to investigate the effect of acute synaptic activation on APP trafficking within dendrites.
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| 6. |
- Tampellini, Davide, et al.
(författare)
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Impaired β-Amyloid Secretion in Alzheimer's Disease Pathogenesis.
- 2011
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Ingår i: The Journal of Neuroscience : the official journal of the Society for Neuroscience. - 1529-2401. ; 31:43, s. 15384-15390
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Tidskriftsartikel (refereegranskat)abstract
- A central question in Alzheimer's disease (AD) research is what role β-amyloid peptide (Aβ) plays in synaptic dysfunction. Synaptic activity increases Aβ secretion, potentially inhibiting synapses, but also decreases intraneuronal Aβ, protecting synapses. We now show that levels of secreted Aβ fall with time in culture in neurons of AD-transgenic mice, but not wild-type mice. Moreover, the ability of synaptic activity to elevate secreted Aβ and reduce intraneuronal Aβ becomes impaired in AD-transgenic but not wild-type neurons with time in culture. We demonstrate that synaptic activity promotes an increase in the Aβ-degrading protease neprilysin at the cell surface and a concomitant increase in colocalization with Aβ42. Remarkably, AD-transgenic but not wild-type neurons show reduced levels of neprilysin with time in culture. This impaired ability to secrete Aβ and reduce intraneuronal Aβ has important implications for the pathogenesis and treatment of AD.
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