Endoplasmic reticulum stress sensors (ER stress sensors)

The endoplasmic reticulum (ER) stress sensors are a group of three primary transmembrane proteins—inositol-requiring enzyme 1 alpha (IRE1α), eukaryotic translation initiation factor 2-alpha kinase 3 (PERK), and activating transcription factor 6 (ATF6)—that monitor the protein-folding environment within the ER lumen (Hetz et al., 2020, Nature Reviews Molecular Cell Biology). Under conditions of proteotoxic stress, these sensors initiate the unfolded protein response (UPR) to restore homeostasis by expanding ER capacity, reducing protein translation, and increasing chaperone production (Wang & Kaufman, 2016, Nature). If stress is chronic or irremediable, the sensors pivot the signaling toward programmed cell death, primarily through the induction of pro-apoptotic factors like CHOP (Maly & Papa, 2014, Chemical Reviews). These pathways are frequently hijacked in cancer to promote tumor survival under harsh conditions and are implicated in the pathogenesis of neurodegenerative diseases and metabolic disorders like type 2 diabetes (Hetz & Saxena, 2017, Neuron). Pharmacological modulation of these sensors, such as IRE1α RNase inhibitors or PERK kinase inhibitors, is being explored to either sensitize cancer cells to apoptosis or protect neurons from proteotoxicity (Axten et al., 2012, Journal of Medicinal Chemistry). However, therapeutic development is challenged by the essential role of these sensors in secretory tissues, particularly the pancreas, where inhibition can lead to significant toxicity. Current research focuses on identifying selective modulators that can fine-tune the UPR without triggering systemic adverse effects.

Other names

Unfolded protein response sensorsUPR sensorsER stress transducersIRE1-PERK-ATF6 system

Modulation of the unfolded protein response (UPR) by inhibiting or activating the signaling cascades of Inositol-requiring enzyme 1 alpha, Eukaryotic translation initiation factor 2-alpha kinase 3, or Activating transcription factor 6 to either restore cellular proteostasis or trigger apoptosis in diseased cells (Hetz et al., 2020, Nature Reviews Molecular Cell Biology).