Advances in Heat Shock Proteomics: Towards a Better Understanding of the Physiology and Pathophysiology of Molecular Chaperones.

Chaperones are a large group of unrelated protein families that stabilize unfolded proteins, unfold them for translocation across membranes or degradation, and assist in their correct folding and assembly. They represent one of the most ancient and evolutionarily conserved protective protein families found in nature. A fundamental group of molecular chaperones is the so-called heat shock proteins (HSPs), also known as stress proteins. Originally discovered as inducible molecules capable of maintaining cellular homeostasis against abrupt temperature changes, HSPs were later considered an adaptive physiological response that protects against a variety of different cellular proteotoxic stresses. Early in the study of these proteins, it was evident that these molecules also have physiological roles that facilitate the synthesis, folding, assembly, trafficking, and secretion of specific proteins in various cellular compartments in the absence of significant pathological processes. In summary, these proteins guard the cellular proteome against misfolding and inappropriate aggregation. From a clinical point of view, modification of the chaperone proteome, mainly the induction of HSPs, has been observed in a wide spectrum of inflammatory and degenerative diseases, including cancer, infectious disease, autoimmune processes, neurodegenerative conditions, and prion disease. The involvement of HSPs in these diverse diseases highlights the importance of the chaperone machinery not only in cell biology, but also in pathophysiology. At the same time, the induction of HSPs in diseases suggests potential clinical applications for molecular chaperones, particularly HSPS, in the diagnosis, prognosis and, above all, therapy of different degenerative and inflammatory human diseases. On this basis, proteomic approaches represent a valuable method to study the roles, structural interrelationships, and intimate molecular mechanisms of the major chaperone families that have been insufficiently characterized, limiting their diagnostic and therapeutic potential.