stability of the transthyretin molecule as a key factor in the interaction with a-beta peptide - relevance in alzheimers disease转体基因分子的稳定性的一个关键因素与a -β-淀粉样蛋白肽-阿尔茨海默氏症的相关性.pdf

Stability of the Transthyretin Molecule as a Key Factor in the Interaction with A-Beta Peptide - Relevance in Alzheimer’s Disease 1,2 ˜ 1,2 1,3 Carlos A. Ribeiro , Maria Joao Saraiva , Isabel Cardoso * ˆ ´ 1 Molecular Neurobiology Unit, IBMC- Instituto de Biologia Molecular e Celular, Porto, Portugal, 2 ICBAS- Instituto de Ciencias Biomedicas Abel Salazar, Porto Portugal, ´ ´ 3 Escola Superior de Tecnologia da Saude do Porto, Instituto Politecnico do Porto, Vila Nova de Gaia, Portugal Abstract Transthyretin (TTR) protects against A-Beta toxicity by binding the peptide thus inhibiting its aggregation. Previous work showed different TTR mutations interact differently with A-Beta, with increasing affinities correlating with decreasing amyloidogenecity of the TTR mutant; this did not impact on the levels of inhibition of A-Beta aggregation, as assessed by transmission electron microscopy. Our work aimed at probing differences in binding to A-Beta by WT, T119M and L55P TTR using quantitative assays, and at identifying factors affecting this interaction. We addressed the impact of such factors in TTR ability to degrade A-Beta. Using a dot blot approach with the anti-oligomeric antibody A11, we showed that A-Beta formed oligomers transiently, indicating aggregation and fibril formation, whereas in the presence of WT and T119M TTR the oligomers persisted longer, indicative that these variants avoided further aggregation into fibrils. In contrast, L55PTTR was not able to inhibit oligomerization or to prevent evolution to aggregates and fibrils. Furthermore, apoptosis a