Development of a novel yeast cell-based system for studying the aggregation of Alzheimer's disease-associated A beta peptides in vivo

Alzheimer's disease is the most common neurodegenerative disease, affecting -50% of humans by age 85. The disease process is associated with aggregation of the AP peptides, short 39-43 residue peptides generated through endoproteolytic cleavage of the Alzheimer's precursor protein. While the process of aggregation of purified AP peptides in vitro is beginning to be well understood, little is known about this process in vivo. In the present study, we use the yeast Saccharomyces cerevisiae as a model system for studying A beta-mediated aggregation in an organism in vivo. One of this yeast's endogenous prions, Sup35/[PSI+] loses the ability to aggregate when the prion-forming domain of this protein is deleted. We show that insertion of AP pepticle sequences in place of the original prion domain of this protein restores its ability to aggregate. However, the aggregates are qualitatively different from [PSI+] prions in their sensitivity to detergents and in their requirements on transacting factors that are normally needed for [PSI+] propagation. We conclude that we have established a useful new tool for studying the aggregation of AP peptides in an organism in vivo.