The fucosyltransferase FucT-VII regulates E-selectin ligand synthesis in human T cells.

Abstract

Abstract. Selectin-ligands on T cells contribute to the recruitment of circulating cells into chronic inflammatory lesions in the skin and elsewhere. This report provides the first evidence that a single fucosyltransferase, termed FucT-VII, controls the synthesis of E-selectin ligands in human T-lymphoblasts. The FucT-IV transferase (the ELFT enzyme), in contrast, constructs lower avidity E-selectin ligands and requires enzyme levels found only in myeloid cells. Treatment of Jurkat cells with phorbol myristate acetate increased the expression of sialylated LewisX-related (sLeX-related) epitopes and induced the synthesis of E-selectin ligands functional at physiologic levels of linear shear-stress. Northern analysis revealed a parallel increase in the steady-state level of FucT-VII mRNA, but there were no increases in the two other leukocyte-associated fucosyltransferases (FucT-IV and VI). The stable transfection of the FucT-VII gene into Jurkat cells induced high levels of the sLeX-related epitopes and the synthesis of E-selectin ligands which equaled or exceeded the avidity of those on circulating lymphocytes. The growth of T-lymphoblasts under conditions which induced expression of the sLe x,a epitopes increased the level of FucT-VII mRNA, the synthesis of sialylated-Lewis x structures by cell-free extracts and the synthesis of E-selectin ligands equal in avidity to those on FucT-VII transfectants. In contrast, neither the mRNA levels nor activities of the FucT-IV and VI enzymes increased in association with E-selectin ligand synthesis in T-lymphoblasts. Myeloid cell lines, unlike lymphoblasts, expressed high levels of both the FucT-VII and IV enzymes in conjunction with E-selectin ligands raising the possibility that both enzymes contributed to ligand synthesis. FucT-IV transfected Jurkat cells synthesized low avidity ligands for E-selectin but only in association with the CDw65 (VIM-2) carbohydrate epitope. Only blood neutrophils and myeloid cell lines expressed this epitope at the levels associated with E-ligand synthesis in the transfectants. In contrast, native Jurkat cells, blood monocytes, blood lymphocytes, and cultured T-lymphoblasts expressed low levels or none. We conclude that FucT-VII is a principal regulator of E-selectin ligand synthesis in human T-lymphoblasts while both FucT-VII and FucT-IV may direct ligand synthesis in some myeloid cells. Correlative studies in several species suggest that these molecules participate in recruitment. T-lymphocytes expressing carbohydrate epitopes associated with ligands for

Activation of Murine CD4+ and CD8+ T Lymphocytes Leads to Dramatic Remodeling ofN-Linked Glycans

“…The additional increased expression of fucosyl-and sialyltransferases in Th1 cells promotes synthesis of the selectin ligand sialyl-Lewis X (NeuAc␣2-3Gal␤1-4[Fuca1-3]GlcNAc), while Th2 helper cells lack sialyl-Lewis X sequences because a key fucosyltransferase, Fuc-T VII, is not expressed. Such differential glycosylation accounts for the selectin-mediated recruitment of CD4 Th1 cells to sites of inflammation (11)(12)(13)(14)(15)(16)(17).…”

Skin-Homing Receptors on Effector Leukocytes Are Differentially Sensitive to Glyco-Metabolic Antagonism in Allergic Contact Dermatitis

“…In vivo models of T cell-mediated inflammation reveal that E-and P-selectin ligand function and skin-tropic behavior on T cells are dependent on ␣1,3 fucosyltransferases IV and VII (FT4/7) (7,9,10). These enzymes are responsible for generating sialyl Lewis X moieties on T cell membrane protein and lipid scaffolds, conferring ligand activity and the skin-homing designation of leukocytes (11)(12)(13)(14)(15)(16)(17)(18). Prior studies using metabolic inhibitors of selectin ligand biosynthesis, namely 4-fluorinated N-acetylglucosamine (4-F-GlcNAc), also show that preventing the formation of sialyl Lewis X moieties inhibits the recruitment of effector T cells to inflamed skin (19,20).…”

Differing Requirements for CCR4, E-Selectin, and α4β1 for the Migration of Memory CD4 and Activated T Cells to Dermal Inflammation

“…The difference in the migration of these two CCR4 + CD4 cells may be related to the increased ESL expression on CD4 cells after activation (Fig. 4C) as a result of the induction of a1,3-fucosyl transferases in the activated cells (51,52).…”