Native metastable prefibrillar oligomers are the most neurotoxic species among amyloid aggregates

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE

卷:1842

Article

Diociaiuti, Marco¹  Macchia, Gianfranco²  Paradisi, Silvia²  Frank, Claudio³  Camerini, Serena²  Chistolini, Pietro¹  Gaudiano, Maria Cristina⁴  Petrucci, Tamara Corinna²  Malchiodi-Albedi, Fiorella² 

[1] Ist Super Sanita, Dept Technol & Hlth, I-00161 Rome, Italy

[2] Ist Super Sanita, Dept Cell Biol & Neurosci, I-00161 Rome, Italy

[3] Ist Super Sanita, Natl Ctr Rare Dis, I-00161 Rome, Italy

[4] Ist Super Sanita, Dept Therapeut Res & Med Evaluat, I-00161 Rome, Italy

关键词: Amyloid oligomers;    Neurotoxicity;    Structural biophysics;    Neurodegenerative diseases;   

DOI  :  10.1016/j.bbadis.2014.06.006

来源: Elsevier

【 摘 要 】

Many proteins belonging to the amyloid family share the tendency to misfold and aggregate following common steps, and display similar neurotoxicity. In the aggregation pathway different kinds of species are formed, including several types of oligomers and eventually mature fibers. It is now suggested that the pathogenic aggregates are not the mature fibrils, but the intermediate, soluble oligomers. Many kinds of aggregates have been described to exist in a metastable state and in equilibrium with monomers. Up to now it is not clear whether a specific structure is at the basis of the neurotoxicity. Here we characterized, starting from the early aggregation stages, the oligomer populations formed by an amyloid protein, salmon calcitonin (sCT), chosen. due to its very slow aggregation rate. To prepare different oligomer populations and characterize them by means of photoinduced cross-linking SDS-PAGE, Energy Filtered-Transmission Electron Microscopy (EF-TEM) and Circular Dichroism (CD) spectroscopy, we used Size Exclusion Chromatography (SEC), a technique that does not influence the aggregation process leaving the protein in the native state. Taking advantage of sCT low aggregation rate, we characterized the neurotoxic potential of the SEC-separated, non-crosslinked fractions in cultured primary hippocampal neurons, analyzing intracellular Ca2+ influx and apoptotic trend. We provide evidence that native, globular, metastable, prefibrillar oligomers (dimers, trimers and tetramers) were the toxic species and that low concentrations of these aggregates in the population was sufficient to render the sample neurotoxic. Monomers and other kind of aggregates, such as annular or linear protofibers and mature fibers, were totally biologically inactive. (C) 2014 Elsevier B.V. All rights reserved.

【 授权许可】

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