Endoplasmic Reticulum Stress in Hearing Loss

The endoplasmic reticulum (ER) plays important roles in coordinating protein biosynthesis and secretion in the cell. Accumulation of misfolded and/or unfolded proteins in the ER causes ER stress and the so-called unfolded protein response (UPR). The UPR alleviates ER stress through blocking protein synthesis and activating expression of chaperone genes, whereas prolonged UPR could induce cell death. Recent research has showed that ER stress and UPR are involved in hearing loss. Accordingly, animal experiments showed that chemical chaperones or ER stress inducers alleviate environment-related hearing loss, whereas ER stress inhibitor has been used to treat certain types of hereditary deafness. Further investigations are needed to fully understand the detailed mechanisms of how ER stress contributes to the loss of auditory function, which will help us to eventually develop ER-stress-related treatment of various types of deafness.