Heat Shock Proteins
Introduction
Heat shock proteins (HSPs) are a group of proteins that are produced by cells in response to exposure to stressful conditions. They were first described in relation to heat shock, but are now known to also be expressed during other types of stress such as exposure to cold, UV light, and during wound healing or tissue remodeling. Many members of this group perform chaperone function by stabilizing new proteins to ensure correct folding or by helping to refold proteins that were damaged by the cell stress. This increase in expression is transcriptionally regulated. The dramatic upregulation of the heat shock proteins is a key part of the heat shock response and is induced primarily by heat shock factor (HSF).
Classification
Heat shock proteins are named according to their molecular weight. For example, Hsp60, Hsp70 and Hsp90 (the most widely-studied HSPs) refer to families of heat shock proteins on the order of 60, 70, and 90 kilodaltons in size, respectively. The smaller heat shock proteins like Hsp10, Hsp27, and alpha-crystallin (a type of Hsp20) are also crucial in protein maintenance.
Function
Heat shock proteins have powerful protective functions that have broad implications for human health and disease. The heat shock response, controlled by the transcription factor heat shock factor, leads to the increased expression of heat shock proteins, which then act as molecular chaperones to prevent protein aggregation and promote the refolding and repair of damaged proteins.
Role in Disease and Medicine
Heat shock proteins play an important role in disease states and in the immune response. Some cancers express heat shock proteins, which can prevent the misfolding of proteins and thus allow cancer cells to survive. Autoimmune diseases, such as rheumatoid arthritis, have been linked to heat shock proteins. In terms of therapeutic applications, heat shock proteins have been shown to be part of the stress response that can be manipulated to increase the survival of cells and tissues that have been damaged by disease or injury.