Modulation of O-glycans and N-glycans on murine CD8 T cells fails to alter annexin V ligand induction by galectin 1.
Thymic negative selection and contraction of responding T cell oligoclones after infection represent important cell ablation processes required for maintaining T cell homeostasis. It has been proposed that galectin 1 contributes to these processes through interaction with lactosyl sequences principally on cell surface glycoproteins bearing core 2 (C2GnT1)-branched O-glycans. According to this model, specific T cell surface proteins cross-linked by galectin 1 induce signaling, ligand redistribution, and apoptosis in both immature thymocytes and activated T cells. The influence of lactosyl residues contained in branched O-glycans or complex N-glycans on galectin 1 binding and induction of annexin V ligand in murine CD8 T cells was assessed. Neither galectin binding nor galectin-induced expression of annexin V ligand was perturbed under conditions in which: 1) C2GnT1 activity was differentially induced by CD8 T cell activation/culture with IL-2 vs IL-4; 2) activated CD8(+) T cells lacked C2GnT1 expression; or 3) complex N-glycan formation was blocked by swainsonine. The maintenance of galectin 1 binding and induced annexin V expression under conditions that alter lactosamine abundance on O- or complex N-glycans suggest that galectin 1-mediated apoptosis is neither a simple function of fluctuating C2GnT1 activity nor a general C2GnT1-dependent mechanism underlying contraction of CD8 T cells subsequent to activation.
Carlow
Douglas A
DA
The Biomedical Research Centre, University of British Columbia, Vancouver, British Columbia, Canada. doug@brc.ubc.ca
Williams
Michael J
MJ
Ziltener
Hermann J
HJ
D000606:Amino Sugars / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D017304:Annexin A5 / Q000096:biosynthesis / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002470:Cell Survival / Q000276:immunology; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D016207:Cytokines / Q000494:pharmacology; D015536:Down-Regulation / Q000276:immunology; D037483:Galectin 1 / Q000494:pharmacology*; D008024:Ligands; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D017351:N-Acetylglucosaminyltransferases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding / Q000276:immunology; D051381:Rats; D018000:Receptors, Peptide / Q000096:biosynthesis*
D000606:Amino Sugars; D017304:Annexin A5; D016207:Cytokines; D037483:Galectin 1; D008024:Ligands; D011134:Polysaccharides; D018000:Receptors, Peptide; C080707:annexin V receptor; D003208:Concanavalin A; C032233:lactosamine; D017351:N-Acetylglucosaminyltransferases; C053024:beta-1,3-galactosyl-O-glycosyl-glycoprotein beta-1,6-acetylglucosaminyl transferase