TY - JOUR
T1 - Sulfated polysaccharides promote the assembly of amyloid β1-42 peptide into stable fibrils of reduced cytotoxicity
AU - Bravo, Ramona
AU - Arimon, Muriel
AU - Valle-Delgado, Juan José
AU - García, Raquel
AU - Durany, Núria
AU - Castel, Susanna
AU - Cruz, Montserrat
AU - Ventura, Salvador
AU - Fernàndez-Busquets, Xavier
PY - 2008/11/21
Y1 - 2008/11/21
N2 - The histopathological hallmarks of Alzheimer disease are the self-aggregation of the amyloid β peptide (Aβ) in extracellular amyloid fibrils and the formation of intraneuronal Tau filaments, but a convincing mechanism connecting both processes has yet to be provided. Here we show that the endogenous polysaccharide chondroitin sulfate B (CSB) promotes the formation of fibrillar structures of the 42-residue fragment, Aβ1-42. Atomic force microscopy visualization, thioflavin T fluorescence, CD measurements, and cell viability assays indicate that CSB-induced fibrils are highly stable entities with abundant β-sheet structure that have little toxicity for neuroblastoma cells. We propose a wedged cylinder model for Aβ1-42 fibrils that is consistent with the majority of available data, it is an energetically favorable assembly that minimizes the exposure of hydrophobic areas, and it explains why fibrils do not grow in thickness. Fluorescence measurements of the effect of different Aβ1-42 species on Ca2+ homeostasis show that weakly structured nodular fibrils, but not CSB-induced smooth fibrils, trigger a rise in cytosolic Ca2+ that depends on the presence of both extracellular and intracellular stocks. In vitro assays indicate that such transient, local Ca2+ increases can have a direct effect in promoting the formation of Tau filaments similar to those isolated from Alzheimer disease brains. © 2008 by The American Society for Biochemistry and Molecular Biology, Inc.
AB - The histopathological hallmarks of Alzheimer disease are the self-aggregation of the amyloid β peptide (Aβ) in extracellular amyloid fibrils and the formation of intraneuronal Tau filaments, but a convincing mechanism connecting both processes has yet to be provided. Here we show that the endogenous polysaccharide chondroitin sulfate B (CSB) promotes the formation of fibrillar structures of the 42-residue fragment, Aβ1-42. Atomic force microscopy visualization, thioflavin T fluorescence, CD measurements, and cell viability assays indicate that CSB-induced fibrils are highly stable entities with abundant β-sheet structure that have little toxicity for neuroblastoma cells. We propose a wedged cylinder model for Aβ1-42 fibrils that is consistent with the majority of available data, it is an energetically favorable assembly that minimizes the exposure of hydrophobic areas, and it explains why fibrils do not grow in thickness. Fluorescence measurements of the effect of different Aβ1-42 species on Ca2+ homeostasis show that weakly structured nodular fibrils, but not CSB-induced smooth fibrils, trigger a rise in cytosolic Ca2+ that depends on the presence of both extracellular and intracellular stocks. In vitro assays indicate that such transient, local Ca2+ increases can have a direct effect in promoting the formation of Tau filaments similar to those isolated from Alzheimer disease brains. © 2008 by The American Society for Biochemistry and Molecular Biology, Inc.
U2 - https://doi.org/10.1074/jbc.M709870200
DO - https://doi.org/10.1074/jbc.M709870200
M3 - Article
VL - 283
SP - 32471
EP - 32483
ER -