| 1. |
- Gatsinzi, Tom, et al.
(författare)
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Localized caspase sensors for live cell imaging of amyloid-β induced apoptosis
- 2010
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 6:4, Supplement, s. S259-S260
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Apoptosis is an evolutionary conserved cellular process important for normal development, maintenance of tissue homeostasis and an effective immune system. Cysteine-aspartic proteases, or caspases, are the major mediators of apoptosis, triggering processes which lead to cellular disruption. Dysregulation of apoptotic signaling has been shown to be involved in several pathological conditions, like cancer and degenerative disorders. Alzheimer's disease (AD) is the most common form of dementia involving massive cell death of neurons. However, the cause of AD at the present time is still unknown, although, amyloid-β (Aβ) peptide has been suggested to be the triggering factor. Methods:In order to detect localized caspase activation in live cells we designed sensors for caspase-3, -6 and -9 utilizing fluorescence resonance energy transfer (FRET). The FRET-ing sensor molecules, consisting of CFP and YFP separated by a linker containing a specific caspase cleavage motif, were designed to signal caspase cleavage by the loss of FRET. Differentiated SH-SY5Y cells were used as a model system for neurodegeneration. The cells were treated with oligomeric Aβ42 or staurosporine as a positive control of apoptosis. The cleavage of the sensors during induced apoptosis was verified by western blot analysis. Time-lapse FRET microscopy was used to monitor caspase activity in different parts of the cells. Results: In our study, when the cells were exposed to staurosporine we were able to detect local activity of caspase-6 initially in the soma of the cells, whereas caspase-6 activity in the neurites was delayed. Furthermore, our study shows that oligomeric Aβ42 is able to activate caspase-3, -6 and -9. In contrast to staurosporine, in Aβ42 treated cells loss of FRET occurred globally indicating that caspase was activated simultaneously in soma and axons. Conclusions: In conclusion, we show that our caspase-sensors are able to detect local caspase activity in vitro. We also show that exposure to oligomeric Aβ42 results in global activation of caspases in differentiated SH-SY5Y cells.
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| 2. |
- Olsson, Veronica, et al.
(författare)
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Analysis of apoptotic processes in live cells
- 2006
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 2:3, Supplement, s. S439-S440
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Neuronal and synaptic loss can be observed in several neurologic disorders, like Alzheimer’s disease (AD). The mechanism behind cell death in AD has been intensively studied and apoptosis has been proposed to play a central role in death processes, primary affecting cholinergic neurons in the cerebral cortex and the limbic lobe. There are numerous potential death stimuli that may be relevant in AD, including inflammatory responses, growth factor deprivation, oxidative stress and direct effects of the β- amyloid peptide. Objective: In order to get further insights in the initiation of apoptotic processes, we have developed a set of caspase sensors. Methods: We have used fluorescence resonance energy transfer (FRET) technology to, in real time and at single cell level, monitor the crucial event of the activation cysteine aspartate proteases, central in apoptosis. The two chromophores ECFP and EYFP, separated by a caspase cleavage site, have been used to visualize the caspase cleavage event at a chosen subcellular location in different cellular models, including differentiated neuronal cells. Since several apoptotic signalling pathways may be involved, we have designed sensors that can be cleaved by caspase-3, -8 or -9, representing two possible pathways, the death receptor pathway and the mitochondrial pathway. The in vitromodel used initially to characterize the caspase sensors has been HeLa cells, stimulated with staurosporin. The condition of the cells and the different stages of apoptosis were identified by nuclear staining with Hoechst 33258. Results: Our preliminary data indicate that caspase cleavage is an early event in the apoptotic cascade initiated by staurosporin, and that it most likely begins central in the cell body as FRET signals can be detected at later stages only in the cell periphery. Over-expression of the sensors did not result in any detectable toxicity since cells were able to divide successfully and no morphological changes could be revealed. Conclusion: Using this approach, a better temporal and spatial understanding of the apoptotic processes will be achieved. This is necessary in order to identify therapeutic targets to prevent the massive loss of neurons in AD and related disorders.
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| 3. |
- Samuelsson, Malin, et al.
(författare)
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Transcription factors as targets to block inflammation in neurodegenerative disorder : s
- 2006
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 2:3, Supplement, s. S457-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Accumulating evidence supports the importance of inflammation in neurodegenerative disorders like Alzheimer’s disease (AD). Epidemiological studies have revealed that patients taking anti-inflammatory drugs for conditions like arthritis have a lower prevalence of Alzheimer’s than others. In addition, there are reports that show that inflammation indeed can cause neurodegeneration in vivo. “The glial loop hypothesis” describes the model where surrounding glial cells are activated and produce neurotoxic products and therefore lead to neuronal death. One of the most important transcription factors involved in the inflammatory signalling cascade is NF-κB (nuclear factor κB). Supporting a role for NF-κB in AD, this transcription factor has been shown to be upregulated in brains from patients suffering from the disease. Another transcription factor family, thought to work together with NF-κB, is CCAAT enhancer binding protein (C/EBP). C/EBPδ has also been shown to be overexpressed in brains from Alzheimer patients. Objective: Our aim was to characterize the activation of transcription factors that may be involved in AD and to investigate the possibilities to block the effects of these transcription factors. Methods: We have used a delivery system that we have previously developed with a decoy non-covalently bound to a cell-penetrating peptide (CPP). In our studies primary mixed glial cultures from rat (5-10% microglia and 90-95% astrocytes) were used as a modelsystem. Transcription factor activation and cytokine mRNA expression were analyzed by electrophoretic mobility shift assay and RT-PCR, respectively. Cellular uptake studies were performed using confocal laser scanning microscopy. Results: Our studies show that a β-amyloid peptide alone or in combination with the inflammatory cytokine interleukin-1β upregulates NF-κB binding activity as well as the mRNA expression of its downstream target gene interleukin-6 (IL-6). Using our delivery system with an NF-κB decoy resulted in inhibition of upregulated NF-κB binding activity by approx. 80% and IL-6 mRNA expression by approx. 50%. We observed a clear uptake of the CPP-coupled decoy. In parallel, we have also investigated the possibility to use C/EBP as a therapeutic target. Conclusion: Facilitated uptake of transcription factor decoys may be a promising strategy to target the inflammation in neurodegenerative disorders like AD.
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| 4. |
- Klementieva, Oxana, et al.
(författare)
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Detection of pre-plaque amyloid aggregation using FTIR
- 2014
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Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5279 .- 1552-5260. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Alzheimer's disease (AD) is characterized by misfolding and aggregation of naturally occurring beta-amyloid peptides (Aβ). These aggregates are thought to be pathogenic to neurons, although the conformation of the pathogenic Aβ species remains unclear. Biochemical extraction methods and different microscopy techniques (TEM, confocal) can be used to identify pathogenic Aβ species in the brain, although such methods can alter protein conformation or are n ot designed to determine structural details of protein assemblies.
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| 5. |
- Mc Donald, J. M., et al.
(författare)
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The aqueous phase of Alzheimer's disease brain contains assemblies built from similar to 4 and similar to 7 kDa A beta species
- 2015
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 11:11, s. 1286-1305
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Much knowledge about amyloid beta (A beta) aggregation and toxicity has been acquired using synthetic peptides and mouse models, whereas less is known about soluble Ab in human brain. Methods: We analyzed aqueous extracts from multiple A beta brains using an array of techniques. Results: Brains can contain at least four different A beta assembly forms including: (i) monomers, (ii) a similar to 7kDa Ab species, and larger species (iii) from similar to 30-150 kDa, and (iv)>160 kDa. High molecular weight species are by far the most prevalent and appear to be built from similar to 7 kDa A beta species. The similar to 7 kDa A beta species resist denaturation by chaotropic agents and have a higher A beta 42/A beta 40 ratio than monomers, and are unreactive with antibodies to Asp1 of Ab or APP residues N-terminal of Asp1. Discussion: Further analysis of brain-derived similar to 7 kDa Ab species, the mechanism by which they assemble and the structures they form should reveal therapeutic and diagnostic opportunities. (C) 2015 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.
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| 6. |
- Shi, Liu, et al.
(författare)
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Replication study of plasma proteins relating to Alzheimer's pathology.
- 2021
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Ingår i: Alzheimer's & dementia : the journal of the Alzheimer's Association. - : Wiley. - 1552-5279 .- 1552-5260. ; 17:9, s. 1452-1464
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Tidskriftsartikel (refereegranskat)abstract
- This study sought to discover and replicate plasma proteomic biomarkers relating to Alzheimer's disease (AD) including both the "ATN" (amyloid/tau/neurodegeneration) diagnostic framework and clinical diagnosis.Plasma proteins from 972 subjects (372 controls, 409 mild cognitive impairment [MCI], and 191 AD) were measured using both SOMAscan and targeted assays, including 4001 and 25 proteins, respectively.Protein co-expression network analysis of SOMAscan data revealed the relation between proteins and "N" varied across different neurodegeneration markers, indicating that the ATN variants are not interchangeable. Using hub proteins, age, and apolipoprotein E ε4 genotype discriminated AD from controls with an area under the curve (AUC) of 0.81 and MCI convertors from non-convertors with an AUC of 0.74. Targeted assays replicated the relation of four proteins with the ATN framework and clinical diagnosis.Our study suggests that blood proteins can predict the presence of AD pathology as measured in the ATN framework as well as clinical diagnosis.
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| 7. |
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| 8. |
- Wang, Jijing, et al.
(författare)
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Testing the link between isoaspartate and Alzheimer's disease etiology
- 2023
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Ingår i: Alzheimer's & Dementia. - : John Wiley & Sons. - 1552-5260 .- 1552-5279. ; 19:4, s. 1491-1502
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Tidskriftsartikel (refereegranskat)abstract
- Isoaspartate (isoAsp) is a damaging amino acid residue formed in proteins as a result of spontaneous deamidation. IsoAsp disrupts protein structures, making them prone to aggregation. Here we strengthened the link between isoAsp and Alzheimer's disease (AD) by novel approaches to isoAsp analysis in human serum albumin (HSA), the most abundant blood protein and a major carrier of amyloid beta (A beta) and phosphorylated tau (p-tau) in blood. We discovered a reduced amount of anti-isoAsp antibodies (P < 0.0001), an elevated isoAsp level in HSA (P < 0.001), more HSA aggregates (P < 0.0001), and increased levels of free A beta (P < 0.01) in AD blood compared to controls. We also found that deamidation significantly reduces HSA capacity to bind with A beta and p-tau (P < 0.05). These suggest the presence in AD of a bottleneck in clearance of A beta and p-tau, leading to their increased concentrations in the brain and facilitating their aggregations there.
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