Identification and Characterization of CMP-NeuAc:GalNAc-IgA1 α2,6-Sialyltransferase in IgA1-producing Cells

Academic Article

Abstract

  • Glycosylation defects occur in several human diseases. In IgA nephropathy, IgA1 contains O-glycans that are galactose-deficient and consist mostly of core 1 α2,6 sialylated N-acetylgalactosamine, a configuration suspected to prevent β1,3 galactosylation. We confirmed the same aberrancy in IgA1 secreted by the human DAKIKI B cell line. Biochemical assays indicated CMP-NeuAc:GalNAc-IgA1 α2,6-sialyltransferase activity in this cell line. However, a candidate enzyme, ST6-GalNAcI, was not transcribed in DAKIKI cells, B cells isolated from blood, or Epstein-Barr virus (EBV)-immortalized IgA1-producing cells from the blood of IgAN patients and healthy controls. Instead, ST6-GalNAcII transcription was detected at a high level. Expression of the ST6-GalNAcII gene and activity of the CMP-NeuAc:GalNAc-IgA1 α2,6-sialyltransferase were higher in IgA1-producing cell lines from IgAN patients than in such cells from healthy controls. These data are the first evidence that human cells that lack ST6-GalNAcI can sialylate core 1 GalNAc-Ser/Thr. © 2007 Elsevier Ltd. All rights reserved.
  • Published In

    Digital Object Identifier (doi)

    Author List

  • Raska M; Moldoveanu Z; Suzuki H; Brown R; Kulhavy R; Andrasi J; Hall S; Vu HL; Carlsson F; Lindahl G
  • Start Page

  • 69
  • End Page

  • 78
  • Volume

  • 369
  • Issue

  • 1