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- Esbjörner Winters, Elin, 1978, et al.
(author)
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Direct Observations of Amyloid beta Self-Assembly in Live Cells Provide Insights into Differences in the Kinetics of A beta(1-40) and A beta(1-42) Aggregation
- 2014
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In: Chemistry and Biology. - : Elsevier BV. - 1074-5521. ; 21:6, s. 732-742
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Journal article (peer-reviewed)abstract
- Insight into how amyloid beta (A beta) aggregation occurs in vivo is vital for understanding the molecular pathways that underlie Alzheimer's disease and requires new techniques that provide detailed kinetic and mechanistic information. Using noninvasive fluorescence lifetime recordings, we imaged the formation of A beta(1-40) and A beta(1-42) aggregates in live cells. For both peptides, the cellular uptake via endocytosis is rapid and spontaneous. They are then retained in lysosomes, where their accumulation leads to aggregation. The kinetics of A beta(1-42) aggregation are considerably faster than those of A beta(1-40) and, unlike those of the latter peptide, show no detectable lag phase. We used superresolution fluorescence imaging to examine the resulting aggregates and could observe compact amyloid structures, likely because of spatial confinement within cellular compartments. Taken together, these findings provide clues as to how A beta aggregation may occur within neurons.
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| 2. |
- Bolognesi, B, et al.
(author)
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The N-terminus of amyloid-beta plays a crucial role in its aggregation and toxicity
- 2010
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In: The FEBS Journal. - : Wiley-Blackwell. - 1742-464X .- 1742-4658. ; 277:Suppl. 1, s. 79-80
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Journal article (other academic/artistic)abstract
- The aggregation of Amyloid Beta (Aß) peptide into insolubleamyloid fibrils that deposit in the brain is one of the primarypathogenic events in Alzheimer’s disease. We have previouslyshown, using a Drosophila model of Aß toxicity, that the N terminus of the Aß peptide, despite being unstructured in themature Aß fibril, nonetheless affects Aß induced neurodegeneration in vivo. In order to understand the contribution of the N terminusof Aß to its aggregation behaviour, we have investigated anumber of rationally designed N-terminal mutants in vitro. We find that single amino acid mutations in this region affect significantlythe kinetics of Aß aggregation in vitro as measured by arange of spectroscopic techniques. Furthermore, we observe striking differences in the morphology of the aggregated speciesformed by these different Aß mutants when imaged with TEM or AFM and also in the ß-sheet content of their mature fibrils. Interestingly, mutants with an increased net charge or lower hydrophobicity tend to show slower aggregation kinetics, and to form more ordered aggregates whereas mutations that reduce net charge or increase hydrophobicity favour faster aggregation kinetics and poorly structured aggregates. In addition, the exposed hydrophobicity of aggregates formed in the early stages of aggregation is correlated to their toxicity. These findings demonstrate not only that the N-terminus of the Aß peptide plays a crucial role in its aggregation and toxicity but also suggest that this region of Aß may modulate in vivo toxicity by altering the conformations of aggregates that it forms.
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| 3. |
- Brorsson, Ann-Christin, et al.
(author)
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Intrinsic determinants of neurotoxic aggregate formation by the amyloid beta peptide
- 2010
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In: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 98:8, s. 1677-84
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Journal article (peer-reviewed)abstract
- The extent to which proteins aggregate into distinct structures ranging from prefibrillar oligomers to amyloid fibrils is key to the pathogenesis of many age-related degenerative diseases. We describe here for the Alzheimer's disease-related amyloid beta peptide (Abeta) an investigation of the sequence-based determinants of the balance between the formation of prefibrillar aggregates and amyloid fibrils. We show that by introducing single-point mutations, it is possible to convert the normally harmless Abeta40 peptide into a pathogenic species by increasing its relative propensity to form prefibrillar but not fibrillar aggregates, and, conversely, to abolish the pathogenicity of the highly neurotoxic E22G Abeta42 peptide by reducing its relative propensity to form prefibrillar species rather than mature fibrillar ones. This observation can be rationalized by the demonstration that whereas regions of the sequence of high aggregation propensity dominate the overall tendency to aggregate, regions with low intrinsic aggregation propensities exert significant control over the balance of the prefibrillar and fibrillar species formed, and therefore play a major role in determining the neurotoxicity of the Abeta peptide.
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