Beta amyloid peptide: from different aggregation forms to the activation of different biochemical pathways

Amyloid beta peptide (Ab) is the major component of amyloid plaques in the brain of individuals aVected by Alzheimer's disease (AD). The formation of the plaques is due to an overproduction of Ab by APP processing, its precursor, and to its ability to convert under specific conditions from its soluble form into highly ordered fibrillar aggregates. Although neuronal degeneration occurs near the amyloid plaques, some studies have suggested that intermediates such as protofibrils or simple oligomers are also involved in AD pathogenesis and even appear to be the more dangerous species in the onset of the pathology. Further, toxic properties of aggregates of different size have been investigated and the obtained results support the hypothesis that different aggregate sizes can induce different degeneration pathways. In the present review some of the knowledge about the biochemical routes of Ab processing and production and the relationship among Ab and oxidative stress, metal homeostasis, inXammatory process, and cell death are summarized. Moreover, current strategies addressing both Wbrillogenesis process and different Ab altered biochemical pathways utilized for therapies are described.