title: Deconstruction of O-glycosylation--GalNAc-T isoforms direct distinct subsets of the O-glycoproteome.
abstract: GalNAc-type O-glycosylation is found on most proteins trafficking through the secretory pathway in metazoan cells. The O-glycoproteome is regulated by up to 20 polypeptide GalNAc-Ts and the contributions and biological functions of individual GalNAc-Ts are poorly understood. Here, we used a zinc-finger nuclease (ZFN)-directed knockout strategy to probe the contributions of the major GalNAc-Ts (GalNAc-T1 and GalNAc-T2) in liver cells and explore how the GalNAc-T repertoire quantitatively affects the O-glycoproteome. We demonstrate that the majority of the O-glycoproteome is covered by redundancy, whereas distinct subsets of substrates are modified by non-redundant functions of GalNAc-T1 and GalNAc-T2. The non-redundant O-glycoproteome subsets and specific transcriptional responses for each isoform are related to different cellular processes; for the GalNAc-T2 isoform, these support a role in lipid metabolism. The results demonstrate that GalNAc-Ts have different non-redundant glycosylation functions, which may affect distinct cellular processes. The data serves as a comprehensive resource for unique GalNAc-T substrates. Our study provides a new view of the differential regulation of the O-glycoproteome, suggesting that the plurality of GalNAc-Ts arose to regulate distinct protein functions and cellular processes.
authors.affiliation: Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark schjoldager@sund.ku.dk hclau@sund.ku.dk.
authors.forename: Katrine T
authors.initials: KT
authors.lastname: Schjoldager
authors.affiliation: Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark.
authors.forename: Hiren J
authors.initials: HJ
authors.lastname: Joshi
authors.affiliation: Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark.
authors.forename: Yun
authors.initials: Y
authors.lastname: Kong
authors.affiliation: Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark.
authors.forename: Christoffer K
authors.initials: CK
authors.lastname: Goth
authors.affiliation: Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark.
authors.forename: Sarah Louise
authors.initials: SL
authors.lastname: King
authors.affiliation: Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark.
authors.forename: Hans H
authors.initials: HH
authors.lastname: Wandall
authors.affiliation: Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark.
authors.forename: Eric P
authors.initials: EP
authors.lastname: Bennett
authors.affiliation: Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark.
authors.forename: Sergey Y
authors.initials: SY
authors.lastname: Vakhrushev
authors.affiliation: Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen N, Denmark schjoldager@sund.ku.dk hclau@sund.ku.dk.
authors.forename: Henrik
authors.initials: H
authors.lastname: Clausen
mesh_terms: D000595:Amino Acid Sequence; D004706:Endodeoxyribonucleases / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D006023:Glycoproteins / Q000378:metabolism*; D006031:Glycosylation; D056945:Hep G2 Cells; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D050356:Lipid Metabolism / Q000235:genetics; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D014158:Transcription, Genetic; D016335:Zinc Fingers; D000097763:Polypeptide N-acetylgalactosaminyltransferase
chemical_list: D004706:Endodeoxyribonucleases; D006023:Glycoproteins; D007527:Isoenzymes; D017350:N-Acetylgalactosaminyltransferases; D000097763:Polypeptide N-acetylgalactosaminyltransferase
keywords: GALNT; apolipoproteins; dimethylation; mass spectrometry