Author: ["Wei Qiang","Wai-Ming Yau","Jun-Xia Lu","John Collinge","Robert Tycko"]
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Abstract
Structural differences in 40- and 42-residue-long amyloid-β fibrils seeded in vitro from the cortical tissue of patients with different clinical subtypes of Alzheimer’s disease suggest that different fibril structures form in different disease variants and with different peptide lengths. In a study of the molecular structures of amyloid-β fibrils that develop in the brain tissue of patients with Alzheimer's disease, Robert Tycko and colleagues used direct structural techniques, including electron microscopy and solid-state nuclear magnetic resonance, to screen fibril structures in a large set of tissue samples from human patients. They find structural differences in 40- and 42-residue-long amyloid-β fibrils seeded in vitro from the cortical tissue of patients with different clinical subtypes of the disease. This suggests that different fibril structures form in different disease variants and with different peptide lengths. 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 conditions1,2,3,4,5,6,7,8,9,10,11,12. Recent experiments1,13,14,15,16 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 phenotypes17,18,19. 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.Cite this article
Qiang, W., Yau, WM., Lu, JX. et al. Structural variation in amyloid-β fibrils from Alzheimer's disease clinical subtypes. Nature 541, 217–221 (2017). https://doi.org/10.1038/nature20814 