title: Structural variation in amyloid-β fibrils from Alzheimer's disease clinical subtypes.
abstract: Aggregation of amyloid-β peptides into fibrils or other self-assembled states is central to the pathogenesis of Alzheimer's disease. Fibrils formed in vitro by 40- and 42-residue amyloid-β peptides (Aβ40 and Aβ42) are polymorphic, with variations in molecular structure that depend on fibril growth conditions. Recent experiments suggest that variations in amyloid-β fibril structure in vivo may correlate with variations in Alzheimer's disease phenotype, in analogy to distinct prion strains that are associated with different clinical and pathological phenotypes. Here we investigate correlations between structural variation and Alzheimer's disease phenotype using solid-state nuclear magnetic resonance (ssNMR) measurements on Aβ40 and Aβ42 fibrils prepared by seeded growth from extracts of Alzheimer's disease brain cortex. We compared two atypical Alzheimer's disease clinical subtypes-the rapidly progressive form (r-AD) and the posterior cortical atrophy variant (PCA-AD)-with a typical prolonged-duration form (t-AD). On the basis of ssNMR data from 37 cortical tissue samples from 18 individuals, we find that a single Aβ40 fibril structure is most abundant in samples from patients with t-AD and PCA-AD, whereas Aβ40 fibrils from r-AD samples exhibit a significantly greater proportion of additional structures. Data for Aβ42 fibrils indicate structural heterogeneity in most samples from all patient categories, with at least two prevalent structures. These results demonstrate the existence of a specific predominant Aβ40 fibril structure in t-AD and PCA-AD, suggest that r-AD may relate to additional fibril structures and indicate that there is a qualitative difference between Aβ40 and Aβ42 aggregates in the brain tissue of patients with Alzheimer's disease.
authors.affiliation: Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Qiang
authors.affiliation: Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Wai-Ming
authors.initials: WM
authors.lastname: Yau
authors.affiliation: Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Jun-Xia
authors.initials: JX
authors.lastname: Lu
authors.affiliation: MRC Prion Unit and Department of Neurodegenerative Disease, UCL Institute of Neurology, London WC1N 3BG, UK.
authors.forename: John
authors.initials: J
authors.lastname: Collinge
authors.affiliation: Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Tycko
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000145:classification* / Q000378:metabolism* / Q000473:pathology; D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D002540:Cerebral Cortex / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D010641:Phenotype; D025341:Principal Component Analysis
chemical_list: D000682:Amyloid; D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)