| 1. |
- Brinkmalm, Gunnar, et al.
(författare)
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An online nano-LC-ESI-FTICR-MS method for comprehensive characterization of endogenous fragments from amyloid β and amyloid precursor protein in human and cat cerebrospinal fluid.
- 2012
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Ingår i: Journal of mass spectrometry : JMS. - : Wiley. - 1096-9888 .- 1076-5174. ; 47:5, s. 591-603
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid precursor protein (APP) is the precursor protein to amyloid β (Aβ), the main constituent of senile plaques in Alzheimer's disease (AD). Endogenous Aβ peptides reflect the APP processing, and greater knowledge of different APP degradation pathways is important to understand the mechanism underlying AD pathology. When one analyzes longer Aβ peptides by low-energy collision-induced dissociation tandem mass spectrometry (MS/MS), mainly long b-fragments are observed, limiting the possibility to determine variations such as amino acid variants or post-translational modifications (PTMs) within the N-terminal half of the peptide. However, by using electron capture dissociation (ECD), we obtained a more comprehensive sequence coverage for several APP/Aβ peptide species, thus enabling a deeper characterization of possible variants and PTMs. Abnormal APP/Aβ processing has also been described in the lysosomal storage disease Niemann-Pick type C and the major large animal used for studying this disease is cat. By ECD MS/MS, a substitution of Asp7 → Glu in cat Aβ was identified. Further, sialylated core 1 like O-glycans at Tyr10, recently discovered in human Aβ (a previously unknown glycosylation type), were identified also in cat cerebrospinal fluid (CSF). It is therefore likely that this unusual type of glycosylation is common for (at least) species belonging to the magnorder Boreoeutheria. We here describe a detailed characterization of endogenous APP/Aβ peptide species in CSF by using an online top-down MS-based method.
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| 2. |
- Brinkmalm, Gunnar, et al.
(författare)
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Soluble amyloid precursor protein α and β in CSF in Alzheimer's disease.
- 2013
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Ingår i: Brain research. - : Elsevier BV. - 1872-6240 .- 0006-8993. ; 1513, s. 117-26
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral accumulation of amyloid β (Aβ) is a pathological hallmark of Alzheimer's disease (AD). Proteolytic processing of amyloid precursor protein (APP) by α- or β-secretase results in two soluble metabolites, sAPPα and sAPPβ, respectively. However, previous data have shown that both α- and β-secretase have multiple cleavage sites. The aim of this study was to characterize the C-termini of sAPPα and sAPPβ in cerebrospinal fluid (CSF) by mass spectrometry (MS) and to evaluate whether different combinations of these fragments better separate between AD patients and controls by comparing two different sAPP immunoassays. Methods: Using immunoprecipitation and high resolution MS, the APP species present in CSF were investigated. CSF levels of sAPPα and sAPPβ from patients with AD (n=43) and from non-demented controls (n=44) were measured using AlphaLISA and MSD immunoassays that employ different antibodies for C-terminal recognition of sAPPα. Results: Four different C-terminal forms of sAPP were identified, sAPPβ-M671, sAPPβ-Y681, sAPPα-Q686, and sAPPα-K687 (APP770 numbering). Neither immunoassay for the sAPP species could separate the two patient groups. The correlation (R(2)) between the two immunoassays was 0.41 for sAPPα and 0.45 for sAPPβ. Conclusion: Using high resolution MS, we show here for the first time that sAPPα in CSF ends at Q686 and K687. The findings also support the conclusion from several previous studies that sAPPα and sAPPβ levels are unaltered in AD.
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| 3. |
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| 4. |
- Pannee, Josef, 1979, et al.
(författare)
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The amyloid-beta degradation pattern in plasma A possible tool for clinical trials in Alzheimer's disease
- 2014
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Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940 .- 1872-7972. ; 573, s. 7-12
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid beta (A beta) is the main component of plaques, the central neuropathological hallmark in Alzheimer's disease (AD). A beta is derived from the amyloid precursor protein (APP) by beta- and gamma-secretase-mediated cleavages. A large number of A beta peptides are found in cerebrospinal fluid and these peptides are produced in specific metabolic pathways, which are important for diagnosis, in drug development and to explore disease pathogenesis. To investigate whether a similar pattern could be found also in blood samples, an immunoprecipitation (IP) based method for enrichment of A beta peptides from human plasma was developed. The peptides were analyzed using matrix-assisted-laser-desorption/ionization time-of-flight/time-of-flight mass spectrometry for A beta profiling and selected reaction monitoring (SRM) for MS quantification of A beta 1-38, A beta 1-40 and A beta 1-42 using tripe quadrupole MS. Sixteen N- or C-terminally truncated A beta peptides were reproducibly detected in human plasma, of which 11 were verified by tandem MS. In a pilot study including 9 AD patients and 10 controls, where A beta 1-38, A beta 1-40 and A beta 1-42 were quantified using SRM, no AD-associated change in plasma levels of the peptides were observed. Using MS-based measurement techniques, we show that several A beta peptides can be monitored in a single analysis and the developed methods have the potential to be used as a read out in clinical trials of drugs affecting APP processing or A beta homeostasis.
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| 5. |
- Paulson, Linda, 1971, et al.
(författare)
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Proteomics and peptidomics in neuroscience. Experience of capabilities and limitations in a neurochemical laboratory.
- 2005
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Ingår i: Journal of mass spectrometry : JMS. - : Wiley. - 1076-5174 .- 1096-9888. ; 40:2, s. 202-13
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Forskningsöversikt (refereegranskat)abstract
- The increasing use of proteomics has created a basis for new strategies to develop methodologies for rapid identification of protein patterns in living organisms. It has also become evident that proteomics has other potential applications than protein and peptide identification, e.g. protein characterization, with the aim of revealing their structure, function(s) and interactions of proteins. In comparative proteomics studies, the protein expression of a certain biological system is compared with another system or the same system under perturbed conditions. Global identification of proteins in neuroscience is extremely complex, owing to the limited availability of biological material and very low concentrations of the molecules. Moreover, in addition to proteins, there are number of peptides that must also be considered in global studies on the central nervous system. In this overview, we focus on and discuss problems related to the different sources of biological material and sample handling, which are part of all preparatory and analytical steps. Straightforward protocols are desirable to avoid excessive purification steps, since loss of material at each step is inevitable. We would like to merge the two worlds of proteomics/peptidomics and neuroscience, and finally we consider different practical and technical aspects, illustrated with examples from our laboratory.
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| 6. |
- Portelius, Erik, 1977, et al.
(författare)
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A novel pathway for amyloid precursor protein processing.
- 2011
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Ingår i: Neurobiology of aging. - : Elsevier BV. - 1558-1497 .- 0197-4580. ; 32:6, s. 1090-98
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid precursor protein (APP) can be proteolytically processed along two pathways, the amyloidogenic that leads to the formation of the 40-42 amino acid long Alzheimer-associated amyloid beta (Abeta) peptide and the non-amyloidogenic in which APP is cut in the middle of the Abeta domain thus precluding Abeta formation. Using immunoprecipitation and mass spectrometry we have shown that Abeta is present in cerebrospinal fluid (CSF) as several shorter isoforms in addition to Abeta1-40 and Abeta1-42. To address the question by which processing pathways these shorter isoforms arise, we have developed a cell model that accurately reflects the Abeta isoform pattern in CSF. Using this model, we determined changes in the Abeta isoform pattern induced by alpha-, beta-, and gamma-secretase inhibitor treatment. All isoforms longer than and including Abeta1-17 were gamma-secretase dependent whereas shorter isoforms were gamma-secretase independent. These shorter isoforms, including Abeta1-14 and Abeta1-15, were reduced by treatment with alpha- and beta-secretase inhibitors, which suggests the existence of a third and previously unknown APP processing pathway involving concerted cleavages of APP by alpha- and beta-secretase.
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| 7. |
- Portelius, Erik, 1977, et al.
(författare)
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Brain Amyloid-Beta Fragment Signatures in Pathological Ageing and Alzheimer's Disease by Hybrid Immunoprecipitation Mass Spectrometry
- 2015
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Ingår i: Neurodegenerative Diseases. - : S. Karger AG. - 1660-2854 .- 1660-2862. ; 15:1, s. 50-57
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Tidskriftsartikel (refereegranskat)abstract
- Background: Senile plaques in Alzheimer's disease (AD) are composed of amyloid-beta (A beta) especially N-truncated forms including A beta(4-42). These are thought to be neurotoxic. However, individuals may live for decades with biomarker evidence of cerebral beta-amyloidosis (positive amyloid PET imaging and/or low cerebrospinal fluid levels of the 42 amino acid form of A beta) without cognitive impairment. This condition may be termed pathological ageing (PA). Objective: To investigate whether there is a difference in the cerebral A beta fragment pattern in brain specimens from non-demented (PA) and demented (AD) individuals expressing the full neuropathological triad of AD (senile plaques, neurofibrillary tangles and neurodegeneration). Methods: We extracted A beta using formic acid and hybrid (6E10 and 4G8) immunoprecipitation from fresh-frozen temporal cortex tissue of 6 elderly individuals (mean age +/- SD:89 +/- 3.5 years) with PA and 10 patients with AD (mean age +/- SD: 72 +/- 8.5 years). The full spectrum of A beta peptides was determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Results: AD patients had generally more N-terminally truncated and pyroglutamate-modified A beta than PA patients, whereas PA patients had on average more A beta(1-40) than AD patients. Conclusion: Senile plaques in AD may have an AB fragment composition distinct from PA with more N-terminally and pyroglutamate-modified A beta peptides that may be linked to neurotoxicity. (C) 2015 S. Karger AG, Basel
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| 8. |
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| 9. |
- Portelius, Erik, 1977, et al.
(författare)
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Exploring Alzheimer molecular pathology in Down's syndrome cerebrospinal fluid.
- 2014
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Ingår i: Neuro-degenerative diseases. - : S. Karger AG. - 1660-2862 .- 1660-2854. ; 14:2, s. 98-106
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Tidskriftsartikel (refereegranskat)abstract
- Individuals with Down's syndrome (DS) develop early Alzheimer's disease (AD) with β-amyloid (Aβ) plaque pathology. The extra amyloid precursor protein (APP) gene copy in DS is believed to result in a 50% increase in Aβ production, but it is unclear how this relates to the development of other AD hallmarks, including axonal degeneration and microglia cell activation, and to other neurological problems in DS, including disturbed sleep regulation.
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| 10. |
- Öhrfelt Olsson, Annika, 1973, et al.
(författare)
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Identification of Novel α-Synuclein Isoforms in Human Brain Tissue by using an Online NanoLC-ESI-FTICR-MS Method.
- 2011
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Ingår i: Neurochemical research. - : Springer Science and Business Media LLC. - 1573-6903 .- 0364-3190. ; 36:11, s. 2029-2042
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Tidskriftsartikel (refereegranskat)abstract
- Parkinson's disease (PD) and Dementia with Lewy bodies (DLB) are neurodegenerative diseases that are characterized by intra-neuronal inclusions of Lewy bodies in distinct brain regions. These inclusions consist mainly of aggregated α-synuclein (α-syn) protein. The present study used immunoprecipitation combined with nanoflow liquid chromatography (LC) coupled to high resolution electrospray ionization Fourier transform ion cyclotron resonance tandem mass spectrometry (ESI-FTICR-MS/MS) to determine known and novel isoforms of α-syn in brain tissue homogenates. N-terminally acetylated full-length α-syn (Ac-α-syn(1-140)) and two N-terminally acetylated C-terminally truncated forms of α-syn (Ac-α-syn(1-139) and Ac-α-syn(1-103)) were found. The different forms of α-syn were further studied by Western blotting in brain tissue homogenates from the temporal cortex Brodmann area 36 (BA36) and the dorsolateral prefrontal cortex BA9 derived from controls, patients with DLB and PD with dementia (PDD). Quantification of α-syn in each brain tissue fraction was performed using a novel enzyme-linked immunosorbent assay (ELISA).
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