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- Portelius, Erik, 1977, et al.
(author)
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A novel pathway for amyloid precursor protein processing.
- 2011
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In: Neurobiology of aging. - : Elsevier BV. - 1558-1497 .- 0197-4580. ; 32:6, s. 1090-98
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Journal article (peer-reviewed)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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| 2. |
- Halim, Adnan, et al.
(author)
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Site-specific characterization of threonine, serine, and tyrosine glycosylations of amyloid precursor protein/amyloid {beta}-peptides in human cerebrospinal fluid.
- 2011
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 108:29, s. 11848-53
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Journal article (peer-reviewed)abstract
- The proteolytic processing of human amyloid precursor protein (APP) into shorter aggregating amyloid β (Aβ)-peptides, e.g., Aβ1-42, is considered a critical step in the pathogenesis of Alzheimer's disease (AD). Although APP is a well-known membrane glycoprotein carrying both N- and O-glycans, nothing is known about the occurrence of released APP/Aβ glycopeptides in cerebrospinal fluid (CSF). We used the 6E10 antibody and immunopurified Aβ peptides and glycopeptides from CSF samples and then liquid chromatography-tandem mass spectrometry for structural analysis using collision-induced dissociation and electron capture dissociation. In addition to 33 unglycosylated APP/Aβ peptides, we identified 37 APP/Aβ glycopeptides with sialylated core 1 like O-glycans attached to Thr(-39, -21, -20, and -13), in a series of APP/AβX-15 glycopeptides, where X was -63, -57, -52, and -45, in relation to Asp1 of the Aβ sequence. Unexpectedly, we also identified a series of 27 glycopeptides, the Aβ1-X series, where X was 20 (DAEFRHDSGYEVHHQKLVFF), 19, 18, 17, 16, and 15, which were all uniquely glycosylated on Tyr10. The Tyr10 linked O-glycans were (Neu5Ac)(1-2)Hex(Neu5Ac)HexNAc-O- structures with the disialylated terminals occasionally O-acetylated or lactonized, indicating a terminal Neu5Acα2,8Neu5Ac linkage. We could not detect any glycosylation of the Aβ1-38/40/42 isoforms. We observed an increase of up to 2.5 times of Tyr10 glycosylated Aβ peptides in CSF in six AD patients compared to seven non-AD patients. APP/Aβ sialylated O-glycans, including that of a Tyr residue, the first in a mammalian protein, may modulate APP processing, inhibiting the amyloidogenic pathway associated with AD.
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| 6. |
- Mattsson, Niklas, 1979, et al.
(author)
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It is all about clearance.
- 2011
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In: Biomarkers in medicine. - 1752-0363. ; 5:2
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Journal article (other academic/artistic)
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| 8. |
- Mustafiz, Tamanna, et al.
(author)
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Characterization of the brain β-amyloid isoform pattern at different ages of Tg2576 mice.
- 2011
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In: Neuro-degenerative diseases. - : S. Karger AG. - 1660-2862 .- 1660-2854. ; 8:5, s. 352-63
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Journal article (peer-reviewed)abstract
- Although genetic and biochemical studies have suggested a cardinal role for β-amyloid (Aβ) in Alzheimer's disease, the underlying mechanism(s) of how Aβ induces neurodegeneration is still unclear. Our objective was to investigate the consequences of Aβ, especially on tau phosphorylation at specific epitopes important for Alzheimer's disease.
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| 9. |
- Portelius, Erik, 1977, et al.
(author)
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Novel Aβ Isoforms in Alzheimer´s Disease - Their Role in Diagnosis and Treatment.
- 2011
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In: Current pharmaceutical design. - 1381-6128. ; 17:25, s. 2594-602
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Research review (peer-reviewed)abstract
- The last decades have witnessed an explosion in studies of the role of amyloid-β (Aβ ) in the progress of the neurodegenerative disorder Alzheimer´s disease (AD) and it is now widely accepted that Aβ is related to the pathogenesis of AD. For example, studies have shown that Aβ is neurotoxic and that the neurotoxicity of Aβ is related to its aggregation state. The concentration of the 42 amino acid form of Aβ (Aβ 1-42) is reduced in the cerebrospinal fluid (CSF) from AD patients, which is believed to reflect the AD pathology with plaques in the brain acting as sinks. Less well investigated, however, is the ability of other Aβ isoforms to distinguish AD patients from controls and to identify treatment effects in clinical trials. Recently, novel C-truncated forms of Aβ (Aβ1-14, Aβ1-15, and Aβ1-16) were identified in human CSF. The presence of these small peptides is consistent with a catabolic amyloid precursor protein cleavage pathway by β- followed by α-secretase. It has been shown that Aβ1-14, Aβ1-15, and Aβ1-16 increase dose-dependently in response to γ-secretase inhibitor treatment while Aβ1-42 levels are unchanged. Here, we review the many aspects of Aβ and its isoforms with special focus on their potential role as diagnostic and theragnostic markers.
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