title: Forcible destruction of severely misfolded mammalian glycoproteins by the non-glycoprotein ERAD pathway.
abstract: Glycoproteins and non-glycoproteins possessing unfolded/misfolded parts in their luminal regions are cleared from the endoplasmic reticulum (ER) by ER-associated degradation (ERAD)-L with distinct mechanisms. Two-step mannose trimming from Man9GlcNAc2 is crucial in the ERAD-L of glycoproteins. We recently showed that this process is initiated by EDEM2 and completed by EDEM3/EDEM1. Here, we constructed chicken and human cells simultaneously deficient in EDEM1/2/3 and analyzed the fates of four ERAD-L substrates containing three potential N-glycosylation sites. We found that native but unstable or somewhat unfolded glycoproteins, such as ATF6α, ATF6α(C), CD3-δ-ΔTM, and EMC1, were stabilized in EDEM1/2/3 triple knockout cells. In marked contrast, degradation of severely misfolded glycoproteins, such as null Hong Kong (NHK) and deletion or insertion mutants of ATF6α(C), CD3-δ-ΔTM, and EMC1, was delayed only at early chase periods, but they were eventually degraded as in wild-type cells. Thus, higher eukaryotes are able to extract severely misfolded glycoproteins from glycoprotein ERAD and target them to the non-glycoprotein ERAD pathway to maintain the homeostasis of the ER.
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki 444-8787, Japan Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki 444-8787, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ninagawa
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Okada
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Sumitomo
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Horimoto
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Sugimoto
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
authors.forename: Tokiro
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takeda
authors.affiliation: Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Glycometabolome Team, Systems Glycobiology Research Group, RIKEN Global Research Cluster, Wako, Saitama 351-0198, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki 444-8787, Japan Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki 444-8787, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Kamiya
authors.affiliation: Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki 444-8787, Japan Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki 444-8787, Japan Graduate School of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya, 467-8603, Japan kkato@phar.nagoya-cu.ac.jp mori@upr.biophys.kyoto-u.ac.jp.
authors.forename: Koichi
authors.initials: K
authors.lastname: Kato
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan kkato@phar.nagoya-cu.ac.jp mori@upr.biophys.kyoto-u.ac.jp.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Mori
mesh_terms: D051702:Activating Transcription Factor 6 / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics; D059865:Endoplasmic Reticulum Stress; D060746:Endoplasmic Reticulum-Associated Degradation; D055786:Gene Knockout Techniques; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D045325:HCT116 Cells; D006801:Humans; D008361:Mannosidases / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics; D017510:Protein Folding; D043323:alpha-Mannosidase / Q000235:genetics
chemical_list: C497111:ATF6 protein, human; D051702:Activating Transcription Factor 6; D002135:Calcium-Binding Proteins; C486654:EDEM1 protein, human; D006023:Glycoproteins; D008565:Membrane Proteins; D008361:Mannosidases; C497155:EDEM2 protein, human; C573113:EDEM3 protein, human; D043323:alpha-Mannosidase