Endoplasmic reticulum stress in disease

Proper protein folding in the endoplasmic reticulum (ER) is subject to alterations in the extracellular, as well as the intracellular environment. The accumulation of misfolded proteins in the ER activates the unfolded protein response (UPR), a collection of adaptive signaling pathways that are essential to maintain protein-folding homeostasis in all eukaryotic cells. The UPR reduces protein influx into the ER, increases ER folding capacity, and directs misfolded proteins to degradation. If protein misfolding is not resolved, cells activate death pathways. Protein misfolding in the ER contributes to the etiologies of many diseases and targeting the UPR may provide novel therapies for many pathologies.