title: GTDC2 modifies O-mannosylated α-dystroglycan in the endoplasmic reticulum to generate N-acetyl glucosamine epitopes reactive with CTD110.6 antibody.
abstract: Hypoglycosylation is a common characteristic of dystroglycanopathy, which is a group of congenital muscular dystrophies. More than ten genes have been implicated in α-dystroglycanopathies that are associated with the defect in the O-mannosylation pathway. One such gene is GTDC2, which was recently reported to encode O-mannose β-1,4-N-acetylglucosaminyltransferase. Here we show that GTDC2 generates CTD110.6 antibody-reactive N-acetylglucosamine (GlcNAc) epitopes on the O-mannosylated α-dystroglycan (α-DG). Using the antibody, we show that mutations of GTDC2 identified in Walker-Warburg syndrome and alanine-substitution of conserved residues between GTDC2 and EGF domain O-GlcNAc transferase resulted in decreased glycosylation. Moreover, GTDC2-modified GlcNAc epitopes are localized in the endoplasmic reticulum (ER). These data suggested that GTDC2 is a novel glycosyltransferase catalyzing GlcNAcylation of O-mannosylated α-DG in the ER. CTD110.6 antibody may be useful to detect a specific form of GlcNAcylated O-mannose and to analyze defective O-glycosylation in α-dystroglycanopathies.
authors.affiliation: Department of Biochemistry II, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-0065, Japan; Department of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, Japan.
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Ogawa
authors.forename: Naosuke
authors.initials: N
authors.lastname: Nakamura
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Nakayama
authors.forename: Akira
authors.initials: A
authors.lastname: Kurosaka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Manya
authors.forename: Motoi
authors.initials: M
authors.lastname: Kanagawa
authors.forename: Tamao
authors.initials: T
authors.lastname: Endo
authors.forename: Koichi
authors.initials: K
authors.lastname: Furukawa
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Okajima
mesh_terms: D000117:Acetylglucosamine / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000276:immunology; D049030:Dystroglycans / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000276:immunology / Q000378:metabolism*; D000939:Epitopes / Q000276:immunology / Q000378:metabolism*; D006031:Glycosylation; D016695:Glycosyltransferases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D009154:Mutation; D017434:Protein Structure, Tertiary; D058494:Walker-Warburg Syndrome / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D000906:Antibodies; D000939:Epitopes; D049030:Dystroglycans; D016695:Glycosyltransferases; C576562:POMGNT2 protein, human; D000117:Acetylglucosamine
keywords: CTD110.6; DG; EGF; EGF domain O-GlcNAc transferase; EOGT; ER; GTDC2; GlcNAc; N-Acetylglucosamine; N-acetylglucosamine; dystroglycan; endoplasmic reticulum; epidermal growth factor; α-Dystroglycan