title: Endoplasmic reticulum stress up-regulates Nedd4-2 to induce autophagy.
abstract: The accumulation of unfolded proteins within the endoplasmic reticulum (ER) causes ER stress and activation of unfolded protein response (UPR). This response can trigger ER-associated degradation and autophagy, which clear unfolded proteins and restore protein homeostasis. Recently, it has become clear that ubiquitination plays an important role in the regulation of autophagy. In the present study, we investigated how the E3 ubiquitin ligase neural precursor cell-expressed, developmentally down-regulated protein 4-2 (Nedd4-2) interacts with ER stress and autophagy. In mice, we found that an increase in the expression of Nedd4-2, which was concomitant with the activation of the UPR and autophagy, was caused by a prolonged high-fructose and high-fat diet that induces ER stress in the liver. Pharmacologic induction of ER stress also led to an increase in Nedd4-2 expression in cultured cells, which was coincident with UPR and autophagy activation. The inhibition of inositol-requiring enzyme 1 significantly suppressed Nedd4-2 expression. Moreover, increased Nedd4-2 expression in vivo was closely associated with the activation of inositol-requiring enzyme 1 and increased expression of the spliced form of X-box binding protein 1. Furthermore, knockdown of Nedd4-2 in cultured cells suppressed both basal autophagy and ER stress-induced autophagy, whereas overexpression of Nedd4-2-induced autophagy. Taken together, our findings provide evidence that Nedd4-2 is up-regulated in response to ER stress by the spliced form of X-box binding protein 1 and that this is important in the induction of an appropriate autophagic response.-Wang, H. Sun, R.-Q., Camera, D., Zeng, X.-Y., Jo, E., Chan, S. M. H., Herbert, T. P., Molero, J. C., Ye, J.-M. Endoplasmic reticulum stress up-regulates Nedd4-2 to induce autophagy.
authors.affiliation: Lipid Biology and Metabolic Disease Laboratory, School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Victoria, Australia.
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.affiliation: Lipid Biology and Metabolic Disease Laboratory, School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Victoria, Australia.
authors.forename: Ruo-Qiong
authors.initials: RQ
authors.lastname: Sun
authors.affiliation: Lipid Biology and Metabolic Disease Laboratory, School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Victoria, Australia.
authors.forename: Daria
authors.initials: D
authors.lastname: Camera
authors.affiliation: Lipid Biology and Metabolic Disease Laboratory, School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Victoria, Australia.
authors.forename: Xiao-Yi
authors.initials: XY
authors.lastname: Zeng
authors.affiliation: Lipid Biology and Metabolic Disease Laboratory, School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Victoria, Australia.
authors.forename: Eunjung
authors.initials: E
authors.lastname: Jo
authors.affiliation: Lipid Biology and Metabolic Disease Laboratory, School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Victoria, Australia.
authors.forename: Stanley M H
authors.initials: SM
authors.lastname: Chan
authors.affiliation: Lipid Biology and Metabolic Disease Laboratory, School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Victoria, Australia.
authors.forename: Terence P
authors.initials: TP
authors.lastname: Herbert
authors.affiliation: Lipid Biology and Metabolic Disease Laboratory, School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Victoria, Australia juan.molero@rmit.edu.au.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Molero
authors.affiliation: Lipid Biology and Metabolic Disease Laboratory, School of Health and Biomedical Sciences, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Victoria, Australia jiming.ye@rmit.edu.au.
authors.forename: Ji-Ming
authors.initials: JM
authors.lastname: Ye
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000502:physiology*; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D000075702:Nedd4 Ubiquitin Protein Ligases; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology*; D000071717:X-Box Binding Protein 1 / Q000235:genetics / Q000378:metabolism
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; C000618485:Nedd4L protein, human; C000618461:Nedd4l protein, mouse; D044767:Ubiquitin-Protein Ligases
keywords: Nedd4l; UPR; autophagosome; ubiquitin ligase