title: Inhibition of post-translational N-glycosylation by HRD1 that controls the fate of ABCG5/8 transporter.
abstract: N-glycosylation of proteins in endoplasmic reticulum is critical for protein quality control. We showed here a post-translational N-glycosylation affected by the HRD1 E3 ubiquitin ligase. Both WT- and E3-defective C329S-HRD1 decreased the level of high mannose form of ABCG8, a protein that heterodimerizes with ABCG5 to control sterol balance. Meanwhile, HRD1 increased the non-glycosylated ABCG8 regardless of its E3 activity, thereby suppressing full maturation of ABCG5/8 transporter. Pulse chase and mutational analysis indicated that HRD1 inhibits STT3B-dependent post-translational N-glycosylation of ABCG8. Whereas, HRD1 had only slight effect on the N-glycosylation status of ABCG5; rather it accelerated ABCG5 degradation in an E3 activity-dependent manner. Finally, RMA1, another E3 ubiquitin ligase, accelerated the degradation of both ABCG5 and ABCG8 via E3 activity-dependent manner. HRD1 and RMA1 may therefore be negative regulators of disease-associated transporter ABCG5/ABCG8. The findings also highlight the unexpected E3 activity-independent role of HRD1 in the regulation of N-glycosylation.
authors.affiliation: 1] Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-Ku, Kumamoto 862-0973, Japan [2].
authors.forename: Shingo
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: 1] Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-Ku, Kumamoto 862-0973, Japan [2].
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Shuto
authors.affiliation: 1] Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-Ku, Kumamoto 862-0973, Japan [2].
authors.forename: Takashi
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Medical Therapeutics and Molecular Therapeutics, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kaneko
authors.affiliation: Department of Pharmacy, The University of Tokyo Hospital, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Tappei
authors.initials: T
authors.lastname: Takada
authors.affiliation: Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-Ku, Kumamoto 862-0973, Japan.
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Suico
authors.affiliation: Department of Cell and Developmental Biology, School of Medicine, 526 Taylor Hall, University of North Carolina, Chapel Hill, North Carolina 27599-7090, USA.
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Cyr
authors.affiliation: Department of Pharmacy, The University of Tokyo Hospital, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-Honmachi, Chuo-Ku, Kumamoto 862-0973, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kai
mesh_terms: D000071018:ATP Binding Cassette Transporter, Subfamily G, Member 5; D000071019:ATP Binding Cassette Transporter, Subfamily G, Member 8; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000378:metabolism*; D025461:Feedback, Physiological / Q000502:physiology; D006031:Glycosylation; D006801:Humans; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000378:metabolism*
chemical_list: C416945:ABCG5 protein, human; C416946:ABCG8 protein, human; D000071018:ATP Binding Cassette Transporter, Subfamily G, Member 5; D000071019:ATP Binding Cassette Transporter, Subfamily G, Member 8; D018528:ATP-Binding Cassette Transporters; D008074:Lipoproteins; C482345:SYVN1 protein, human; D044767:Ubiquitin-Protein Ligases