Kayed R, Head E, Sarsoza F, Saing T, Cotman CW, Necula M et al. Fibril specific, conformation dependent antibodies recognize a generic epitope common to amyloid fibrils and fibrillar oligomers that is absent in prefibrillar oligomers. Mol Neurodegener 2: 18

Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA. .
Molecular Neurodegeneration (Impact Factor: 6.56). 02/2007; 2(1):18. DOI: 10.1186/1750-1326-2-18
Source: PubMed


Amyloid-related degenerative diseases are associated with the accumulation of misfolded proteins as amyloid fibrils in tissue. In Alzheimer disease (AD), amyloid accumulates in several distinct types of insoluble plaque deposits, intracellular Abeta and as soluble oligomers and the relationships between these deposits and their pathological significance remains unclear. Conformation dependent antibodies have been reported that specifically recognize distinct assembly states of amyloids, including prefibrillar oligomers and fibrils.
We immunized rabbits with a morphologically homogeneous population of Abeta42 fibrils. The resulting immune serum (OC) specifically recognizes fibrils, but not random coil monomer or prefibrillar oligomers, indicating fibrils display a distinct conformation dependent epitope that is absent in prefibrillar oligomers. The fibril epitope is also displayed by fibrils of other types of amyloids, indicating that the epitope is a generic feature of the polypeptide backbone. The fibril specific antibody also recognizes 100,000 x G soluble fibrillar oligomers ranging in size from dimer to greater than 250 kDa on western blots. The fibrillar oligomers recognized by OC are immunologically distinct from prefibrillar oligomers recognized by A11, even though their sizes overlap broadly, indicating that size is not a reliable indicator of oligomer conformation. The immune response to prefibrillar oligomers and fibrils is not sequence specific and antisera of the same specificity are produced in response to immunization with islet amyloid polypeptide prefibrillar oligomer mimics and fibrils. The fibril specific antibodies stain all types of amyloid deposits in human AD brain. Diffuse amyloid deposits stain intensely with anti-fibril antibody although they are thioflavin S negative, suggesting that they are indeed fibrillar in conformation. OC also stains islet amyloid deposits in transgenic mouse models of type II diabetes, demonstrating its generic specificity for amyloid fibrils.
Since the fibril specific antibodies are conformation dependent, sequence-independent, and recognize epitopes that are distinct from those present in prefibrillar oligomers, they may have broad utility for detecting and characterizing the accumulation of amyloid fibrils and fibrillar type oligomers in degenerative diseases.

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Available from: Rakez Kayed, Oct 04, 2015
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    • "A11 and OC immunoreactivity disappeared when extracts were immunodepleted of Ab using a mixture of Ab antibodies prior to immunoblotting (Figures S2C and S2D), demonstrating that the oligomers seen by A11 and OC in the brains of APP transgenic mice were indeed composed of Ab. These results show that A11 and OC antibodies recognize different structures generated in vivo, as there exist brain-derived Ab assemblies that are A11-positive/OC- negative (in young Tg2576 and hAPP-J20 mice) or OC-posi- tive/A11-negative (in rTg9191 mice), extending the findings that OC and A11 recognize mutually exclusive epitopes on synthetic Abo generated in vitro (Kayed et al., 2007; Wu et al., 2010). "
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    ABSTRACT: The accumulation of amyloid-β (Aβ) as amyloid fibrils and toxic oligomers is an important step in the development of Alzheimer's disease (AD). However, there are numerous potentially toxic oligomers and little is known about their neurological effects when generated in the living brain. Here we show that Aβ oligomers can be assigned to one of at least two classes (type 1 and type 2) based on their temporal, spatial, and structural relationships to amyloid fibrils. The type 2 oligomers are related to amyloid fibrils and represent the majority of oligomers generated in vivo, but they remain confined to the vicinity of amyloid plaques and do not impair cognition at levels relevant to AD. Type 1 oligomers are unrelated to amyloid fibrils and may have greater potential to cause global neural dysfunction in AD because they are dispersed. These results refine our understanding of the pathogenicity of Aβ oligomers in vivo. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Cell Reports 06/2015; 11(11). DOI:10.1016/j.celrep.2015.05.021 · 8.36 Impact Factor
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    • "), confirming that in the context of reduced CIC levels, ATXN1 tends to form more organized fibrillar aggregates. We also probed FRA membranes with OC, a conformational antibody that specifically recognizes fibrillar oligomers and fibrils (Kayed et al., 2007), and found fractions 7 and 8 in Atxn1 154Q/+ mice, and fractions 7, 8, and 9 in Atxn1 154Q/+ ;Cic L+/-mice, positive for OC (Figure 4—figure supplement 3). ATXN1 thus tends to form fibrillar oligomers, amorphous aggregates and/or fibrils when CIC levels are reduced. "
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    ABSTRACT: Recent studies indicate that soluble oligomers drive pathogenesis in several neurodegenerative proteinopathies, including Alzheimer and Parkinson disease. Curiously, the same conformational antibody recognizes different disease-related oligomers, despite the variations in clinical presentation and brain regions affected, suggesting that the oligomer structure might be responsible for toxicity. We investigated whether polyglutamine-expanded Ataxin1, the protein that underlies spinocerebellar ataxia type 1, forms toxic oligomers and, if so, what underlies their toxicity. We found that mutant ATXN1 does form oligomers and that oligomer levels correlate with disease progression in the Atxn1(154Q/+) mice. Moreover, oligomeric toxicity, stabilization and seeding require interaction with Capicua, which is expressed at greater ratios with respect to ATXN1 in the cerebellum than in less vulnerable brain regions. Thus, specific interactors, not merely oligomeric structure, drive pathogenesis and contribute to regional vulnerability. Identifying interactors that stabilize toxic oligomeric complexes could answer longstanding questions about the pathogenesis of other proteinopathies.
    eLife Sciences 05/2015; 4. DOI:10.7554/eLife.07558 · 9.32 Impact Factor
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    • "folded monomers ( blue and red ) ( PDB entries 1BEG , 2LFM , 2GSP , and 2OTK ) . ( Georganopoulou et al . , 2005 ; Chikae et al . , 2008 ; Santos et al . , 2008 ; Herskovits et al . , 2013 ) . scrambled Aβ ( Walsh et al . , 2002 ) . There is plenty of direct exper - imental evidence to support the notion of toxic oligomers ( Walsh et al . , 2002 ; Kayed et al . , 2003 , 2007 ; Haass and Selkoe , 2007 ; Tomic et al . , 2009 ; Mucke and Selkoe , 2012 ; Lesne et al . , 2013 ) , also suggesting that the activity of causing dementia may occur across a broad oligomer range . For example , Aβ dodecamers were identified in human brain extracts and found to bind cul - tured neurons in a manner similar to synthetic A"
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    ABSTRACT: Amyloid-beta (Aβ) peptide oligomers are believed to be the causative agents of Alzheimer's disease (AD). Though post-mortem examination shows that insoluble fibrils are deposited in the brains of AD patients in the form of intracellular (tangles) and extracellular (plaques) deposits, it has been observed that cognitive impairment is linked to synaptic dysfunction in the stages of the illness well before the appearance of these mature deposits. Increasing evidence suggests that the most toxic forms of Aβ are soluble low-oligomer ligands whose amounts better correlate with the extent of cognitive loss in patients than the amounts of fibrillar insoluble forms. Therefore, these ligands hold the key to a better understanding of AD prompting the search for clearer correlations between their structure and toxicity. The importance of such correlations and their diagnostic value for the early diagnosis of AD is discussed here with a particular emphasis on the transient nature and structural plasticity of misfolded Aβ oligomers.
    Frontiers in Chemistry 03/2015; 1(3). DOI:10.3389/fchem.2015.00017
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