title: ER stress-induced clearance of misfolded GPI-anchored proteins via the secretory pathway.
abstract: Proteins destined for the cell surface are first assessed in the endoplasmic reticulum (ER) for proper folding before release into the secretory pathway. This ensures that defective proteins are normally prevented from entering the extracellular environment, where they could be disruptive. Here, we report that, when ER folding capacity is saturated during stress, misfolded glycosylphosphatidylinositol-anchored proteins dissociate from resident ER chaperones, engage export receptors, and quantitatively leave the ER via vesicular transport to the Golgi. Clearance from the ER commences within minutes of acute ER stress, before the transcriptional component of the unfolded protein response is activated. These aberrant proteins then access the cell surface transiently before destruction in lysosomes. Inhibiting this stress-induced pathway by depleting the ER-export receptors leads to aggregation of the ER-retained misfolded protein. Thus, this rapid response alleviates the elevated burden of misfolded proteins in the ER at the onset of ER stress, promoting protein homeostasis in the ER.
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
authors.forename: Prasanna
authors.initials: P
authors.lastname: Satpute-Krishnan
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
authors.forename: Monica
authors.initials: M
authors.lastname: Ajinkya
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
authors.forename: Savithri
authors.initials: S
authors.lastname: Bhat
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Itakura
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK. Electronic address: rhegde@mrc-lmb.cam.ac.uk.
authors.forename: Ramanujan S
authors.initials: RS
authors.lastname: Hegde
authors.affiliation: Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA. Electronic address: lippincj@mail.nih.gov.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lippincott-Schwartz
mesh_terms: D000818:Animals; D002460:Cell Line; D059865:Endoplasmic Reticulum Stress; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*; D051379:Mice; D011328:Prions / Q000378:metabolism; D017510:Protein Folding; D051381:Rats; D055571:Secretory Pathway; D056811:Unfolded Protein Response
chemical_list: D011328:Prions
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