Heat shock proteins (HSPs), also called stress proteins, are not only induced in response to elevated temperatures, but also as a result of various stress situations, including environmental strains, viral infection, ischemia, anoxia and oxidative stress. These stress situations trigger cellular defence mechanisms that act as an emergency system capable of combatting the toxic consequences due to the accumulation of misfolded proteins.

Heat shock proteins are involved in many physiological processes, including development and differentiation, organisation of the cytoarchitecture by binding to cytoskeletal elements and regulation of the balance between cell death and survival. Many heat shock proteins work as molecular chaperones. In this role, they contribute to in vivo protein folding and prevent nonproductive interactions with other proteins and cellular components. In recent years it has been found that the chaperone system and the proteolytic machinery work closely together, and that proteasomal inhibition causes the upregulation of stress proteins. Impairment of the proteasomal machinery and chaperone functions lead to protein damage, which contributes to neurodegenerative disorders and to the aging process.

The brain is the most sensitive target for traumatic events. Many disorders of the nervous system are caused by intracellular or extracellular deposits of protein aggregates. Stress responses in the brain, as monitored by the induction of heat shock proteins, occur in distinct regions and affect nerve cells and glia in a cell-type-specific manner. Hence, stress proteins may serve as biomarkers and provide diagnostic tools that allow us to identify stress specificity and localize pathological processes. Their critical involvement during neurodegeneration in brain disorders, such as Alzheimer’s, Parkinson’s and Huntington’s diseases, and multiple sclerosis, makes them promising candidates for therapeutic intervention and drug development.