Ubiquitin and heat shock proteins in cultured nervous tissue after different stress conditions.

Ubiquitin (Ub) and Heat Shock Proteins (HSP) are believed to act jointly in the recovery process of an organism exposed to a stress. Ubiquitin has been recently found associated with paired helical filaments (PHF) in tangles of Alzheimer disease (AD) and Progressive Supranuclear Palsy (PSP) and with abnormal structures in other degenerative diseases, suggesting a role in their pathogenesis. To elucidate the mechanism of action, functions and relationship of Ub and the HSPs in the nervous tissue, we applied physical or chemical stress to neurons in culture. Rat dorsal root ganglia (DRG) explants were exposed either to aluminum lactate or to heat shock, the stress response was then studied with biochemical and immunological methods. The results show a clear dissociation in the formation of Ub-conjugates and the induction of the major HSPs, depending on the type of stress conditions.