title: A Phos-tag-based approach reveals the extent of physiological endoplasmic reticulum stress.
abstract: Cellular response to endoplasmic reticulum (ER) stress or unfolded protein response (UPR) is a key defense mechanism associated with many human diseases. Despite its basic and clinical importance, the extent of ER stress inflicted by physiological and pathophysiological conditions remains difficult to quantitate, posing a huge obstacle that has hindered our further understanding of physiological UPR and its future therapeutic potential. Here we have optimized a Phos-tag-based system to detect the activation status of two proximal UPR sensors at the ER membrane. This method allowed for a quantitative assessment of the level of stress in the ER. Our data revealed quantitatively the extent of tissue-specific basal ER stress as well as ER stress caused by the accumulation of misfolded proteins and the fasting-refeeding cycle. Our study may pave the foundation for future studies on physiological UPR, aid in the diagnosis of ER-associated diseases and improve and facilitate therapeutic strategies targeting UPR in vivo.
authors.affiliation: Graduate Program in Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York, United States of America.
authors.forename: Liu
authors.initials: L
authors.lastname: Yang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Xue
authors.forename: Yin
authors.initials: Y
authors.lastname: He
authors.forename: Shengyi
authors.initials: S
authors.lastname: Sun
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Ling
authors.initials: L
authors.lastname: Qi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004722:Endoribonucleases / Q000378:metabolism; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D017510:Protein Folding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011725:Pyridines / Q000737:chemistry*; D013312:Stress, Physiological / Q000235:genetics / Q000502:physiology*; D019892:eIF-2 Kinase / Q000378:metabolism
chemical_list: D004722:Endoribonucleases; D017346:Protein Serine-Threonine Kinases; D011725:Pyridines; D019892:eIF-2 Kinase; C514153:1,3-bis(bis(pyridin-2-ylmethyl)amino)propan-2-ol; C528229:ERN1 protein, human