Endoplasmic reticulum stress in biological processing and disease.

The ability of translated cellular proteins to perform their functions requires their proper folding after synthesis. The endoplasmic reticulum (ER) is responsible for coordinating protein folding and maturation. Infections, genetic mutations, environmental factors and many other conditions can lead to challenges to the ER known as ER stress. Altering ER homeostasis results in accumulation of misfolded or unfolded proteins. To eliminate this problem, a response is initiated by the cell called the unfolded protein response (UPR), which involves multiple signaling pathways. Prolonged ER stress or a dysregulated UPR can lead to premature apoptosis and an exaggerated inflammatory response. Following these discoveries, ER stress was shown to be related to several chronic diseases, such as diabetes mellitus, neurodegenerative disorders, fatty liver disease and inflammatory bowel disease that have not yet been clearly demonstrated pathophysiologically. Here, we review the field and present up-to-date information on the relationship between biological processing, ER stress, UPR, and several chronic diseases.