| 1. |
- Almandoz-Gil, Leire, et al.
(författare)
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Low molar excess of 4-oxo-2-nonenal and 4-hydroxy-2-nonenal promote oligomerization of alpha-synuclein through different pathways
- 2017
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Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 110, s. 421-431
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Tidskriftsartikel (refereegranskat)abstract
- Aggregated alpha-synuclein is the main component of Lewy bodies, intraneuronal inclusions found in brains with Parkinson's disease and dementia with Lewy bodies. A body of evidence implicates oxidative stress in the pathogenesis of these diseases. For example, a large excess (30:1, aldehyde:protein) of the lipid peroxidation end products 4-oxo-2-nonenal (ONE) or 4-hydroxy-2-nonenal (HNE) can induce alpha-synuclein oligomer formation. The objective of the study was to investigate the effect of these reactive aldehydes on alpha-synuclein at a lower molar excess (3:1) at both physiological (7.4) and acidic (5.4) pH. As observed by size-exclusion chromatography, ONE rapidly induced the formation of alpha-synuclein oligomers at both pH values, but the effect was less pronounced under the acidic condition. In contrast, only a small proportion of alpha-synuclein oligomers were formed with low excess HNE-treatment at physiological pH and no oligomers at all under the acidic condition. With prolonged incubation times (up to 96 h), more alpha-synuclein was oligomerized at physiological pH for both ONE and HNE. As determined by Western blot, ONE-oligomers were more SDS-stable and to a higher-degree cross-linked as compared to the HNE-induced oligomers. However, as shown by their greater sensitivity to proteinase K treatment, ONE-oligomers, exhibited a less compact structure than HNE-oligomers. As indicated by mass spectrometry, ONE modified most Lys residues, whereas HNE primarily modified the His50 residue and fewer Lys residues, albeit to a higher degree than ONE. Taken together, our data show that the aldehydes ONE and HNE can modify alpha-synuclein and induce oligomerization, even at low molar excess, but to a higher degree at physiological pH and seemingly through different pathways.
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| 2. |
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| 3. |
- Fagerqvist, Therese, et al.
(författare)
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Monoclonal antibodies selective for α-synuclein oligomers/protofibrils recognize brain pathology in Lewy body disorders and α-synuclein transgenic mice with the disease-causing A30P mutation
- 2013
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Ingår i: Journal of Neurochemistry. - : Wiley-Blackwell. - 0022-3042 .- 1471-4159. ; 126:1, s. 131-144
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Tidskriftsartikel (refereegranskat)abstract
- Inclusions of intraneuronal alpha-synuclein (-synuclein) can be detected in brains of patients with Parkinson's disease and dementia with Lewy bodies. The aggregation of -synuclein is a central feature of the disease pathogenesis. Among the different -synuclein species, large oligomers/protofibrils have particular neurotoxic properties and should therefore be suitable as both therapeutic and diagnostic targets. Two monoclonal antibodies, mAb38F and mAb38E2, with high affinity and strong selectivity for large -synuclein oligomers were generated. These antibodies, which do not bind amyloid-beta or tau, recognize Lewy body pathology in brains from patients with Parkinson's disease and dementia with Lewy bodies and detect pathology earlier in -synuclein transgenic mice than linear epitope antibodies. An oligomer-selective sandwich ELISA, based on mAb38F, was set up to analyze brain extracts of the transgenic mice. The overall levels of -synuclein oligomers/protofibrils were found to increase with age in these mice, although the levels displayed a large interindividual variation. Upon subcellular fractionation, higher levels of -synuclein oligomers/protofibrils could be detected in the endoplasmic reticulum around the age when behavioral disturbances develop. In summary, our novel oligomer-selective -synuclein antibodies recognize relevant pathology and should be important tools to further explore the pathogenic mechanisms in Lewy body disorders. Moreover, they could be potential candidates both for immunotherapy and as reagents in an assay to assess a potential disease biomarker.
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| 4. |
- Keller, Lina, et al.
(författare)
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The PSEN1 I143T mutation in a Swedish family with Alzheimer's disease: clinical report and quantification of A beta in different brain regions
- 2010
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Ingår i: European Journal of Human Genetics. - London : Springer Science and Business Media LLC. - 1476-5438 .- 1018-4813. ; 18:11, s. 1202-1208
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Tidskriftsartikel (refereegranskat)abstract
- Early-onset dominantly inherited forms of Alzheimer's disease (AD) are rare, but studies of such cases have revealed important information about the disease mechanisms. Importantly, mutations in amyloid precursor protein (APP), presenilin 1 (PSEN1) and PSEN2, alter the APP processing and lead to an increased amyloid beta-peptide (A beta) 42/40 ratio. This, together with other studies on pathogenic mechanisms, show that A beta 42 is a major player in the etiology of AD. Here, we present a clinical and neuropathological description of a Swedish family with an I143T mutation in the PSEN1 gene, which gives rise to a severe form of AD. We also performed an extensive investigation on the concentration and distribution of A beta species of different lengths in six brain regions from two mutation carriers. Our study showed that A beta 42 and a longer peptide, A beta 43, were present both in plaque cores and in total amyloid preparations, and were each clearly more frequent than A beta 40 in all examined regions, as shown by both mass spectrometry and immunohistochemistry. European Journal of Human Genetics (2010) 18, 1202-1208; doi: 10.1038/ejhg.2010.107; published online 14 July 2010
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| 5. |
- Sandebring, Anna, et al.
(författare)
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The Pathogenic A beta 43 Is Enriched in Familial and Sporadic Alzheimer Disease
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:2, s. e55847-
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Tidskriftsartikel (refereegranskat)abstract
- The amyloid-cascade hypothesis posits that the role of amyloid beta-peptide (A beta) in Alzheimer disease (AD) involves polymerization into structures that eventually are deposited as amyloid plaques. During this process, neurotoxic oligomers are formed that induce synaptic loss and neuronal death. Several different isoforms of A beta are produced, of which the 40 and 42 residue variants (A beta 40 and A beta 42) are the most common. A beta 42 has a strong tendency to form neurotoxic aggregates and is involved in AD pathogenesis. Longer A beta isoforms, like the less studied A beta 43, are gaining attention for their higher propensity to aggregate into neurotoxic oligomers. To further investigate A beta 43 in AD, we conducted a quantitative study on A beta 43 levels in human brain. We homogenized human brain tissue and prepared fractions of various solubility; tris buffered saline (TBS), sodium dodecyl sulfate (SDS) and formic acid (FA). Levels of A beta 43, as well as A beta 40 and A beta 42, were quantified using ELISA. We compared quantitative data showing A beta levels in occipital and frontal cortex from sporadic (SAD) and familial (FAD) AD cases, as well as non-demented (ND) controls. Results showed A beta 43 present in each fraction from the SAD and FAD cases, while its level was lower than the detection limit in the majority of the ND-cases. A beta 42 and A beta 43 were enriched in the less soluble fractions (SDS and FA) of SAD and FAD cases in both occipital and frontal cortex. Thus, although the total levels of A beta 43 in human brain are low compared to A beta 40 and A beta 42, we suggest that A beta 43 could initiate the formation of oligomers and amyloid plaques and thereby be crucial to AD pathogenesis.
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| 6. |
- Welander, Hedvig
(författare)
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Alzheimer disease : studies on Abeta and gamma-secretase in human brain
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Alzheimer disease (AD) is a devastating neurodegenerative disorder and the most prevalent form of dementia. One hallmark of the disease is the extracellular deposition of amyloid beta-peptide (Abeta) into senile plaques in the brain. Biochemical and genetic studies reveal Abeta as a key player in AD pathogenesis. The most common forms of Abeta are 40 (Abeta40) or 42 (Abeta42) residues long. Abeta40 is produced at higher levels than Abeta42; while Abeta42 is more hydrophobic, prone to aggregate, and form the toxic species. Thus, the length of the hydrophobic C-terminus of Abeta is very important for oligomerization and neurotoxicity. Abeta is generated through sequential processing of the amyloid beta- precursor protein (APP) by the enzymes beta- and gamma-secretases. The gamma-secretase cleavage is performed by a transmembrane protein complex containing presenilin (PS), nicastrin (Nct), anterior pharynx defective-1 (Aph-1), presenilin enhancer-2 (Pen-2), and possibly other components. The biological understanding of gamma-secretase remains elusive, as does the mechanism by which Abeta causes neurodegeneration in AD. The work presented in this thesis has focused on studies of gamma-secretase activity and localization in mammalian brain, as well as on identification and quantification of Abeta species that are deposited in AD brains. In paper I, a detailed analysis was performed to see how active gamma-secretase is best prepared from brain material, and in what subcellular fraction the activity is highest. The gamma-secretase activity was highly affected by detergents; and the fraction containing endosomes, endoplasmic reticulum, Golgi and synaptic vesicles revealed the highest activity. It was possible to measure Abeta production under the optimized conditions. In paper II, active gamma-secretase was further studied in detergent resistant membranes (DRMs). Active gamma-secretase was localized to DRMs in human and rat brain. The size of DRMs containing active gamma-secretase, and possibly other proteins and lipids, was estimated to be > 2000 kDa. Furthermore, it was possible to measure Abeta production in DRMs. In paper III and paper IV the product of amyloidogenic gamma-secretase cleavage was studied and a detailed investigation performed on Abeta species deposited in AD brains. A method was established for quantification of C-terminal Abeta species in purified plaque cores and in total amyloid preparations fromsporadic and familial AD brains. It was found that a longer Abeta species, i.e. Abeta43, was more frequent than Abeta40. Immunohistochemistry that was performed supported these findings. In paper IV, Abeta species were quantified in six different brain regions obtained from two mutation carriers having the I143T PSEN1 mutation, reported here in Sweden for the first time. As in paper III, Abeta43 was much more frequent than Abeta40. In conclusion, we have determined the optimal conditions for studies of active gamma- secretase in brain and have showed that this active enzyme complex is localized to lipid rafts in human and rat brain. Further, we have found a longer Abeta species, Abeta43, to be more frequent than Abeta40 in amyloid depositions in AD brains. This species polymerizes rapidly, and we suggest that Abeta43 may be of importance in AD etiology.
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| 7. |
- Welander, Hedvig, et al.
(författare)
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Gelsolin co-occurs with Lewy bodies in vivo and accelerates alpha-synuclein aggregation in vitro
- 2011
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 412:1, s. 32-38
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Tidskriftsartikel (refereegranskat)abstract
- Deposition of fibrillar alpha-synuclein as Lewy bodies is the neuropathological hallmark of Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Apart from alpha-synuclein, these intraneuronal inclusions contain over 250 different proteins. The actin binding protein gelsolin, has previously been suggested to be part of the Lewy body, but its potential role in alpha-synuclein aggregation remains unknown. Here, we studied the association between gelsolin and alpha-synuclein in brain tissue from PD and DLB patients as well as in a cell model for alpha-synuclein aggregation. Moreover, the potential effect of gelsolin on alpha-synuclein fibrillization was also investigated. Our data demonstrate that gelsolin co-occured with alpha-synuclein in Lewy bodies from affected human brain as well as with Lewy body-like inclusions in alpha-synuclein over expressing cells. Furthermore, in the presence of calcium chloride, gelsolin was found to enhance the aggregation rate of alpha-synuclein in vitro. Moreover, no apparent structural differences could be observed between fibrils formed in the presence or absence of gelsolin. Further studies on gelsolin and other Lewy body associated proteins are warranted to learn more about their potential role in the alpha-synuclein aggregation process.
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| 8. |
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