Physiological IRE-1-XBP-1 and PEK-1 signaling in Caenorhabditis elegans larval development and immunity

• Published in: PLoS genetics 2011-11, Vol.7 (11), p.e1002391-e1002391
• Main Authors: Richardson, Claire E, Kinkel, Stephanie, Kim, Dennis H
• Format: Article
• Language: English
• Subjects: Animals; Biology; Caenorhabditis elegans; Caenorhabditis elegans - genetics; Caenorhabditis elegans - growth & development; Caenorhabditis elegans - immunology; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cellular signal transduction; E coli; Endoplasmic Reticulum Stress - drug effects; Endoplasmic Reticulum Stress - genetics; Experiments; Feedback, Physiological; Gene Expression Regulation, Developmental; Genetic aspects; Genetics; Homeostasis; Homeostasis - genetics; Homeostasis - physiology; Immunity - genetics; Larva - genetics; Larva - growth & development; MAP Kinase Kinase 1 - genetics; MAP Kinase Kinase 1 - metabolism; Mutant Proteins - genetics; Mutant Proteins - metabolism; Nematodes; Phosphorylation; Physiological aspects; Protein folding; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Signal Transduction; Studies; Technological change; Temperature; Transcription factors; Tunicamycin - pharmacology; Unfolded Protein Response - genetics; Unfolded Protein Response - physiology
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1002391

Endoplasmic reticulum (ER) stress activates the Unfolded Protein Response, a compensatory signaling response that is mediated by the IRE-1, PERK/PEK-1, and ATF-6 pathways in metazoans. Genetic studies have implicated roles for UPR signaling in animal development and disease, but the function of the UPR under physiological conditions, in the absence of chemical agents administered to induce ER stress, is not well understood. Here, we show that in Caenorhabditis elegans XBP-1 deficiency results in constitutive ER stress, reflected by increased basal levels of IRE-1 and PEK-1 activity under physiological conditions. We define a dynamic, temperature-dependent requirement for XBP-1 and PEK-1 activities that increases with immune activation and at elevated physiological temperatures in C. elegans. Our data suggest that the negative feedback loops involving the activation of IRE-1-XBP-1 and PEK-1 pathways serve essential roles, not only at the extremes of ER stress, but also in the maintenance of ER homeostasis under physiological conditions.