Negative regulation of T-cell activation and autoimmunity by Mgat5 N-glycosylation

Nature. 2001 Feb 8;409(6821):733-9. doi: 10.1038/35055582.


T-cell activation requires clustering of a threshold number of T-cell receptors (TCRs) at the site of antigen presentation, a number that is reduced by CD28 co-receptor recruitment of signalling proteins to TCRs. Here we demonstrate that a deficiency in beta1,6 N-acetylglucosaminyltransferase V (Mgat5), an enzyme in the N-glycosylation pathway, lowers T-cell activation thresholds by directly enhancing TCR clustering. Mgat5-deficient mice showed kidney autoimmune disease, enhanced delayed-type hypersensitivity, and increased susceptibility to experimental autoimmune encephalomyelitis. Recruitment of TCRs to agonist-coated beads, TCR signalling, actin microfilament re-organization, and agonist-induced proliferation were all enhanced in Mgat5-/- T cells. Mgat5 initiates GlcNAc beta1,6 branching on N-glycans, thereby increasing N-acetyllactosamine, the ligand for galectins, which are proteins known to modulate T-cell proliferation and apoptosis. Indeed, galectin-3 was associated with the TCR complex at the cell surface, an interaction dependent on Mgat5. Pre-treatment of wild-type T cells with lactose to compete for galectin binding produced a phenocopy of Mgat5-/- TCR clustering. These data indicate that a galectin-glycoprotein lattice strengthened by Mgat5-modified glycans restricts TCR recruitment to the site of antigen presentation. Dysregulation of Mgat5 in humans may increase susceptibility to autoimmune diseases, such as multiple sclerosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Differentiation / metabolism
  • Autoimmunity*
  • Galectin 3
  • Glycosylation
  • Humans
  • Hypersensitivity, Delayed
  • Lymphocyte Activation*
  • Major Histocompatibility Complex
  • Mice
  • N-Acetylglucosaminyltransferases / deficiency
  • N-Acetylglucosaminyltransferases / metabolism*
  • Polysaccharides / metabolism
  • Receptors, Antigen, T-Cell / metabolism
  • Signal Transduction
  • T-Lymphocytes / immunology*


  • Antigens, Differentiation
  • Galectin 3
  • Polysaccharides
  • Receptors, Antigen, T-Cell
  • N-Acetylglucosaminyltransferases
  • alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase