Differential regulation and impact of fucosyltransferase VII and core 2 β1,6- N-acetyl-glycosaminyltransferase for generation of E-selectin and P-selectin ligands in murine CD4+ T cells.

Ligands for E-selectin and P-selectin ( E-lig and P-lig) are induced on CD4+ T cells upon differentiation into effector T cells. Glycosyltransferases, especially α 1,3-fucosyltransferase VII ( Fuc T-VII) and core 2 β1,6- N-acetyl-glycosaminyltransferase I ( C2 Glc NAc T-I), are critical for their synthesis. We here analysed the signals that control the expression of E-lig, P-lig and m RNA coding for Fuc T-VII and C2 Glc NAc T-I. In line with previous reports, we found that P-lig expression correlates with the regulation of C2 Glc NAc T-I, whereas E-lig expression can occur at low levels of C2 Glc NAc T-I m RNA but requires high Fuc T-VII m RNA expression. Interestingly, the two enzymes are regulated by different signals. Activation-induced C2 Glc NAc T-I up-regulation under permissive (T helper type 1) conditions was strongly reduced by cyclosporin A ( Cs A), suggesting the involvement of T-cell receptor-dependent, calcineurin/ NFAT-dependent signals in combination with interleukin-12 ( IL-12) -mediated signals in the regulation of C2 Glc NAc T-I. In contrast, expression of Fuc T-VII m RNA was not significantly inhibited by Cs A. Interleukin-4 inhibited the expression of Fuc T-VII but IL-2 and IL-7 were found to support induction of Fuc T-VII and E-lig. E-selectin, P-selectin and their ligands initially appeared to have rather overlapping functions. These findings however, unravel striking differences in the regulation of E-lig and P-lig expression, dictated by the dominance of Fuc T-VII and C2 Glc NAc T-I, respectively, and their dependency on signals from either promiscuous or homeostatic cytokines ( Fuc T-VII) or a strong T-cell receptor signal in combination with inflammatory cytokines in case of C2 Glc NAc T-I. [ABSTRACT FROM AUTHOR]