IRE1 Signaling Affects Cell Fate During the Unfolded Protein Response

• Published in: Science (American Association for the Advancement of Science) Vol. 318; no. 5852; pp. 944 - 949
• Main Authors: Lin, Jonathan H, Li, Han, Yasumura, Douglas, Cohen, Hannah R, Zhang, Chao, Panning, Barbara, Shokat, Kevan M, LaVail, Matthew M, Walter, Peter
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 09.11.2007; The American Association for the Advancement of Science
• Subjects: Activating Transcription Factor 6 - metabolism; Animals; Animals, Genetically Modified; Apoptosis; Biological and medical sciences; Cell culture; Cell culture techniques; Cell cycle; Cell death; Cell differentiation, maturation, development, hematopoiesis; Cell Line; Cell lines; Cell physiology; Cell Survival; Cellular biology; Cytoprotection; Disease Models, Animal; eIF-2 Kinase - metabolism; Endoplasmic Reticulum - metabolism; Endoribonucleases - genetics; Endoribonucleases - metabolism; Fundamental and applied biological sciences. Psychology; HEK293 cells; Humans; Kinetics; Membrane Proteins - genetics; Membrane Proteins - metabolism; Messenger RNA; Mice; Molecular and cellular biology; Mutation; Photoreceptors; Protein Folding; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Proteins - chemistry; Proteins - metabolism; Rats; Retina - metabolism; Retinitis Pigmentosa - metabolism; Rhodopsin - chemistry; Rhodopsin - metabolism; Signal Transduction; Splicing; Transcriptional regulatory elements; Transgenic animals; Cell fate; Endoplasmic reticulum
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1146361

Endoplasmic reticulum (ER) stress activates a set of signaling pathways, collectively termed the unfolded protein response (UPR). The three UPR branches (IRE1, PERK, and ATF6) promote cell survival by reducing misfolded protein levels. UPR signaling also promotes apoptotic cell death if ER stress is not alleviated. How the UPR integrates its cytoprotective and proapoptotic outputs to select between life or death cell fates is unknown. We found that IRE1 and ATF6 activities were attenuated by persistent ER stress in human cells. By contrast, PERK signaling, including translational inhibition and proapoptotic transcription regulator Chop induction, was maintained. When IRE1 activity was sustained artificially, cell survival was enhanced, suggesting a causal link between the duration of UPR branch signaling and life or death cell fate after ER stress. Key findings from our studies in cell culture were recapitulated in photoreceptors expressing mutant rhodopsin in animal models of retinitis pigmentosa.