Stability of early-stage amyloid-β(1–42) aggregation species

Coalier, Kelley; Paranjape, Geeta; Karki, Sanjib; Nichols, Michael R.

doi:10.1016/j.bbapap.2012.08.017

Cited by 18 publications

(21 citation statements)

References 33 publications

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“…Our studies indicated that some, but only a small percentage, of Aβ42 protofibrils were trafficked to the lysosome. This finding, and the observation that Aβ42 protofibrils are quite stable (Coalier, et al, 2013), may help to explain our observation that Aβ42 protofibrils were not degraded and cleared after internalization by primary microglial cells.…”

Section: Discussionsupporting

confidence: 60%

Amyloid-β42 protofibrils are internalized by microglia more extensively than monomers

et al. 2016

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One pathological hallmark of Alzheimer’s disease (AD) is the accumulation of amyloid-β peptide (Aβ) in the affected brain. While there are numerous deleterious effects of Aβ accumulation, there is general agreement that a sustained inflammatory response to aggregated Aβ contributes to progressive neurodegeneration in AD and microglial cells play a significant role in this process. Our laboratory and others have shown that small soluble aggregates of Aβ activate a microglia-mediated inflammatory response. One component of the response involves internalization of extracellular Aβ, and this process is likely very sensitive to Aβ structure. In this study we analyzed the proclivity of microglia for internalization of Aβ42 monomers and protofibrils using fluorescently-labeled Aβ. Both Aβ42 species were labeled directly via amino linkage with an Alexa Fluor 488 tetrafluorophenyl ester (AF488-TFP) and then isolated individually by chromatography. Aβ42 protofibrils retained their size and morphological properties after labeling but monomers had a much higher stoichiometry of labeling compared to protofibrils. Primary murine microglia internalized AF488-Aβ42 protofibrils rapidly and in significant amounts compared to AF488-Aβ42 monomers. Microglial internalization of protofibrils was dependent on time and concentration, and corresponded with tumor necrosis factor α secretion. In competition studies, unlabeled Aβ42 protofibril internalization, detected by immunostaining, did not diminish AF488-protofibril uptake. Internalized AF488-Aβ42 protofibrils were found widely dispersed in the cytosol with some lysosomal accumulation but little degradation. These studies highlight the sensitivity that microglia exhibit to Aβ structure in the internalization process and emphasize their affinity for soluble Aβ protofibrils.

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Section: Discussionsupporting

confidence: 60%

Amyloid-β42 protofibrils are internalized by microglia more extensively than monomers

et al. 2016

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“…Under SDS page conditions only limited OC reactive species were detected in both the soluble and insoluble fraction. It is notable that due to the conformational nature of the antibody, only those aggregates which are not denatured upon SDS exposure would remain in a detectable configuration (Coalier et al, 2013). Nevertheless, an increased OC signal (two bands evident at 40-60 kDa) was seen in AD cases when compared to non-AD controls within the soluble fraction as well as in the mid-range smears from the insoluble fraction ( Fig.…”

Section: Detection Of Distinct Soluble and Insoluble Immunoreactive Smentioning

confidence: 91%

“…The amyloid-selective OC antibody recognises a common and conserved conformation within all fibril amyloid proteins, independent of amino acid sequence (Kayed et al, 2007). In relation to Aβ, the OC epitope is rapidly formed from isolated soluble monomers and present within low weight fibrillar oligomers prior to formation of more mature Thioflavin T positive fibrils, themselves also OC reactive (Coalier et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Distinctive temporal profiles of detergent-soluble and -insoluble tau and Aβ species in human Alzheimer’s disease

et al. 2018

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Alzheimer's disease (AD) pathology relevant proteins tau and beta-amyloid (Aβ) exist as an array of post-translationally modified and conformationally altered species with varying abundance, solubility and toxicity. Insoluble neurofibrillary tau tangles and Aβ plaques are end-stage AD hallmarks, yet may carry less disease significance compared to soluble species. At present, it is unclear how soluble and insoluble tau and Aβ relate to each other as well as to disease progression. Here, detergent soluble and insoluble fractions generated from post-mortem human temporal lobe samples (Brodmann area 21) were probed for tau and Aβ markers in immuno-dot assays. Measures were quantified according to diagnosis (AD cf. Non-AD), neuropathological severity, and correlated with disease progression (Braak stages). All markers were elevated within AD cases cf. non-AD controls (p < 0.05) independent of solubility. However, when considered according to neuropathological severity, phospho-tau (detected via CP13 and AT8 antibodies) was elevated early within the soluble fraction (p < 0.05 intermediate cf. low severity) and emerged only later within the insoluble fraction (p < 0.05 high cf. low severity). In contrast, PHF1 phospho-tau, TOC1 reactive tau oligomers and amyloid markers rose within the two fractions simultaneously. Independent of solubility, cognitive correlations were observed for tau makers and for fibrillary amyloid (OC), however only soluble total Aβ was significantly correlated with intellectual impairment. Following the exclusion of end-stage cases, only soluble total Aβ remained correlated with cognition. The data indicate differential rates of protein aggregation during AD progression and confirm the disease relevance of early emerging soluble Aβ species.

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“…Shortly after the dissolution of Aβ, the Aβ in solution appeared to form dimer or similar diffusing species (Figure 4, solution), and other somewhat larger aggregated species with diffusivity values on the order of 20 μm 2 /s (Figure 3a). The observance of monomers and dimers in equilibrium at early stages of aggregation of Aβ in solution has been seen via other methods including chromatography [87, 88] and hydrogen exchange mass spectrometry and others [89, 90]. The observance of larger aggregated species in Aβ solutions that are non-fibril (i.e., they do not bind ThT; Figure 5), such as the more slowly diffusing species seen in FCS (Figure 3a) and TEM micrographs (Figure 2b), is consistent with the formation of the toxic oligomer species.…”

Section: Discussionmentioning

confidence: 99%

Collagen hydrogel confinement of amyloid-βaccelerates aggregation and reduces cytotoxic effects

Simpson¹,

Szeto²,

Boukari

et al. 2019

Preprint

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18Alzheimer's disease (AD) is the most common form of dementia and is associated with the 19 accumulation of amyloid-β (Aβ), a peptide whose aggregation has been associated with neurotoxicity. 20 Drugs targeting Aβ have shown great promise in 2D in vitro models and mouse models, yet preclinical 21 and clinical trials for AD have been highly disappointing. We propose that current in vitro culture 22 systems for discovering and developing AD drugs have significant limitations; specifically, that Aβ 23 aggregation is vastly different in these 2D cultures carried out on flat plastic or glass substrates vs. in a 24 3D environment, such as brain tissue, where Aβ confinement very likely alters aggregation kinetics and 25 thermodynamics. In this work, we identified attenuation of Aβ cytotoxicity in 3D hydrogel culture 26 compared to 2D cell culture. We investigated Aβ structure and aggregation in solution vs. hydrogel using 27Transmission Electron Microscopy (TEM), Fluorescence Correlation Spectroscopy (FCS), and Thioflavin T 28 (ThT) assays. Our results reveal that the equilibrium is shifted to stable β-sheet aggregates in hydrogels 29 and away from the relatively unstable/unstructured presumed toxic oligomeric Aβ species in solution. 30 Volume exclusion imparted by hydrogel confinement stabilizes unfolded, presumably toxic species, 31 promoting stable extended β-sheet fibrils. These results, taken together with the many recent reports 32 that 3D hydrogel cell cultures enable cell morphologies and epigenetic changes that are more similar to 33 cells in vivo compared to 2D cultures, strongly suggest that AD drugs should be tested in 3D culture 34 systems as a step along the development pathway towards new, more effective therapeutics. 35 36

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Stability of early-stage amyloid-β(1–42) aggregation species

Cited by 18 publications

References 33 publications

Amyloid-β42 protofibrils are internalized by microglia more extensively than monomers

Amyloid-β42 protofibrils are internalized by microglia more extensively than monomers

Distinctive temporal profiles of detergent-soluble and -insoluble tau and Aβ species in human Alzheimer’s disease

Collagen hydrogel confinement of amyloid-βaccelerates aggregation and reduces cytotoxic effects

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