Small heat shock proteins differentially affect Aβ aggregation and toxicity

β-Amyloid (Aβ) is the primary protein component of senile plaques in Alzheimer's disease (AD) and has been implicated in neurotoxicity associated with the disease. Aβ aggregates readily in vitro and in vivo, and its toxicity has been linked to its aggregation state. Prevention of Aβ aggregation has been investigated as a means to prevent Aβ toxicity associated with AD. Recently we found that Hsp20 from Babesia bovis prevented both Aβ aggregation and toxicity [S. Lee, K. Carson, A. Rice-Ficht, T. Good, Hsp20, a novel alpha-crystallin, prevents Abeta fibril formation and toxicity, Protein Sci. 14 (2005) 593-601.]. In this work, we examined the mechanism of Hsp20 interaction with Aβ1-40 and compared its activity to that of other small heat shock proteins, carrot Hsp17.7 and human Hsp27. While all three small heat shock proteins were able to prevent Aβ aggregation, only Hsp20 was able to attenuate Aβ toxicity in cultured SH-SY5Y cells. Understanding the mechanism of the Hsp20-Aβ interaction may provide insights into the design of the next generation of Aβ aggregation and toxicity inhibitors.