P-selectin glycoprotein ligand-1 and E-selectin ligand-1 are differentially modified by fucosyltransferases Fuc-TIV and Fuc-TVII in mouse neutrophils

P-selectin glycoprotein ligand-1 (PSGL-1) and E-selectin ligand-l (ESL-1) are the two major selectin ligands on mouse neutrophils, Transfection experiments demonstrate that each ligand requires alpha 1,3-fucosylation for selectin-binding. However, the relative contributions made by the two known myeloid alpha 1,3-fucosyltransferases Fuc-TVII or Fuc-TIV to this alpha 1,3-fucosylation are not yet clear. To address this issue, we have used mice deficient in Fuc-TIV and/or Fuc-TVII to examine how these enzymes generate selectin-binding glycoforms of PSGL-1 and ESL-1 in mouse neutrophils, Selectin binding was analyzed by affinity isolation experiments using recombinant, antibody-like forms of the respective endothelial selectins, We observe essentially normal binding of E- or P-selectin to PSGL-1 expressed by Fuc-TIV-deficient neutrophils but find that PSGL-1 expressed by Fuc-TVII-deficient neutrophils is not bound by E- or P-selectin, By contrast, E-selectin binds with normal efficiency to ESL-1 on Fuc-TVII-deficient neutrophils but exhibits an 80% reduction in its ability to bind ESL-I isolated from Fuc-TIV-deficient neutrophils, The same specificity with which Fuc-TVII and Fuc-TIV generate selectin-binding forms of PSGL-1 and ESL-I was found in transfection experiments with CHO-Pro(-)5 cells. In contrast, each fucosyltransferase alone could generate selectin-binding glycoforms of each of the two ligands in CHO-DUKX-B1 cells. Our data imply that in mouse neutrophils and their precursors, Fuc-TVII exclusively directs expression of PSGL-1 glycoforms bound with high affinity by P-selectin, By contrast, Fuc-TIV preferentially directs expression of ESL-1 glycoforms that exhibit high affinity for E-selectin, This substrate specificity can be mimicked in CHO-Pro(-)5 cells.