The mammalian cytosolic thioredoxin reductase pathway acts via a membrane 1 protein to reduce ER-localised proteins

Cao, X., Lilla, S., Cao, Z., Pringle, M. A., Oka, O. B.V. , Robinson, P. J. , Szmaja, T., Van Lith, M., Zanivan, S. and Bulleid, N. (2020) The mammalian cytosolic thioredoxin reductase pathway acts via a membrane 1 protein to reduce ER-localised proteins. Journal of Cell Science, 133, jcs241976. (doi: 10.1242/jcs.241976) (PMID:32184267) (PMCID:PMC7197872)

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Abstract

Folding of proteins entering the mammalian secretory pathway requires the insertion of the correct disulfides. Disulfide formation involves both an oxidative pathway for their insertion and a reductive pathway to remove incorrectly formed disulfides. Reduction of these disulfides is critical for correct folding and degradation of misfolded proteins. Previously, we showed that the reductive pathway is driven by NADPH generated in the cytosol. Here, by reconstituting the pathway using purified proteins and ER microsomal membranes, we demonstrate that the thioredoxin reductase system provides the minimal cytosolic components required for reducing proteins within the ER lumen. In particular, saturation of the pathway and its protease sensitivity demonstrates the requirement for a membrane protein to shuttle electrons from the cytosol to the ER. These results provide compelling evidence for the critical role of the cytosol in regulating ER redox homeostasis ensuring correct protein folding and facilitating the degradation of misfolded ER proteins.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Van Lith, Dr Marcel and Cao, Dr Zhenbo and Bulleid, Professor Neil and Lilla, Dr Sergio and Szmaja, Tomasz and Zanivan, Professor Sara and Cao, Xiaofei and Robinson, Dr Philip and Oka, Dr Ojore
Authors: Cao, X., Lilla, S., Cao, Z., Pringle, M. A., Oka, O. B.V., Robinson, P. J., Szmaja, T., Van Lith, M., Zanivan, S., and Bulleid, N.
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > Institute of Cancer Sciences
College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Journal of Cell Science
Publisher:Company of Biologists
ISSN:0021-9533
ISSN (Online):1477-9137
Published Online:17 March 2020
Copyright Holders:Copyright © 2020 The Company of Biologists Ltd
First Published:First published in Journal of Cell Science 133:jcs241976
Publisher Policy:Published under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
174173How does the cytosol reduce non-native disulfides formed in the endoplasmic reticulum?Neil BulleidBiotechnology and Biological Sciences Research Council (BBSRC)BB/P017665/1Institute of Molecular, Cell & Systems Biology
190840Protein Folding and Thiol Modification in the Mammalian Endoplasmic ReticulumNeil BulleidWellcome Trust (WELLCOTR)103720/Z/14/ZInstitute of Molecular, Cell & Systems Biology