Sialyl-Lewisx on P-Selectin Glycoprotein Ligand-1 Is Regulated during Differentiation and Maturation of Dendritic Cells: A Mechanism Involving the Glycosyltransferases C2GnT1 and ST3Gal I

Abstract

To fulfil their function as APCs, dendritic cells (DC) and their precursors need to travel from blood to the peripheral tissues and, upon activation, migrate from tissues to draining lymph nodes. Because O-glycans play a role in T cell trafficking, we investigated the O-glycosylation profile of human monocyte-derived DC. Sialyl-Lewisx (sLex), a glycan involved in extravasation via selectin binding, was found to be expressed exclusively on P-selectin glycoprotein ligand-1 in monocytes and immature DC. However, sLex was lost from mature DC even though these cells retained expression of P-selectin glycoprotein ligand-1. Maturation of DC led to a rapid change in the expression of glycosyltransferases involved in O-linked glycosylation. A down-regulation of C2GnT1 mRNA and enzymatic activity was observed with a concurrent up-regulation of ST3Gal I and ST6GalNAc II mRNA resulting in a loss of the core 2 structures required for sLex expression as a P-selectin ligand. Interestingly, the early regulation of these glycosyltransferases was mediated by PGE2, which is known to be required for human DC migration. The pattern of O-glycosylation seen in mature cells was very similar to that expressed by naive T cells, which home to lymph nodes. Our data show that the regulation of O-glycosylation controls sLex expression, and also suggest that O-glycans may have a function in DC migration.

Competition between Core-2 GlcNAc-transferase and ST6GalNAc-transferase Regulates the Synthesis of the Leukocyte Selectin Ligand on Human P-selectin Glycoprotein Ligand-1

“…It also revealed the existence of ␣(2,6) sialylated glycans including the mono-(Gal␤1,3(NeuAc␣2,6) GalNAc; m/z 895.1) and di-(NeuAc␣2,3Gal␤1,3 (NeuAc␣2,6)GalNAc, m/z 1256.3) sialylated T-antigens at this position. Although similar structures have been observed during whole cell O-glycome analysis of a variety of PSGL-1 bearing cells including monocytes, dendritic cells, and neutrophils (34,35), this is the first report of the expression of such glycans at the N terminus of PSGL-1.…”

“…In the case of dendritic cells, maturation is accompanied by a decrease in C2GnT-1 and an increase in ST6GalNAc2 transcript levels (34). Based on the current work, a transition from the core-2 sLe X glycan to the di-sialylated T-antigen may be expected at the PSGL-1 N terminus.…”

Control of TNF-Induced Dendritic Cell Maturation by Hybrid-Type N-Glycans

“…Recently, a genetic remodeling of glycosylation upon DC maturation was demonstrated by glyco-gene microarray expression analysis (6,7) and by quantitative RT-PCR (8,9). A number of transcripts for enzymes involved in N-glycan synthesis was found to be increased during DC differentiation but downregulated after their maturation (6-8, 10, 11).…”

Bovine Herpesvirus 4 Modulates Its β-1,6- N -Acetylglucosaminyltransferase Activity through Alternative Splicing

“…Expression of core 2 structures has been shown to regulate monocyte extravasation and migration of monocyte-derived dendritic cells to lymph nodes (57)(58)(59). BoHV-4 could therefore regulate extravasation of infected monocytes and migration of these cells in tissues or toward draining lymph nodes by modulating glycan structures at the infected cell surface.…”