Endoplasmic Reticulum Stress

Synonyms

Endoplasmic reticulum stress response; ER stress

Definition

The endoplasmic reticulum (ER) is an organelle with several essential functions in eukaryotic cells. The ER is both a major intracellular calcium store and the place where proteins entering the secretory pathway are synthesized, folded, modified and delivered to their final cell surface or extracellular destination. Moreover, in mammalian cells the ER is the site of sterols and lipids synthesis. Disturbance in any of these functions, which results in the disruption of the proper folding and secretory capacity of the ER and increased load of unfolded proteins in its lumen, defines a condition known as “ER stress.” ER stress activates a complex and multifaceted intracellular signal transduction pathway that is essentially designed to re-establish ER homeostasis. Inability to restore ER functions induces cell death, which is usually in the form of apoptosis. ER stress contributes to the