Roles of molecular chaperones in protein misfolding diseases.

Human misfolding diseases result from the failure of proteins to reach their active state or from the accumulation of aberrantly folded proteins. The mechanisms by which molecular chaperones influence the development of these diseases is beginning to be understood. Mutations that compromise the activity of chaperones lead to several rare syndromes. In contrast, the more frequent amyloid-related neurodegenerative diseases are caused by a gain of toxic function of misfolded proteins. Toxicity in these disorders may result from an imbalance between normal chaperone capacity and production of dangerous protein species. Increased chaperone expression can suppress the neurotoxicity of these molecules, suggesting possible therapeutic strategies.