Differential requirements for the O-linked branching enzyme core 2 beta 1-6-N-glucosaminyltransferase in biosynthesis of ligands for E-selectin and P-selectin
Kr. Snapp et al., Differential requirements for the O-linked branching enzyme core 2 beta 1-6-N-glucosaminyltransferase in biosynthesis of ligands for E-selectin and P-selectin, BLOOD, 97(12), 2001, pp. 3806-3811
Selectins are carbohydrate-binding adhesion molecules that play important r
oles in control of leukocyte traffic. Glycosyltransferases involved in sele
ctin ligand biosynthesis include the alpha1,9-fucosyl-transferases FucT-VII
and FucT-IV, one or more sialyltransferases, and at least one O-linked bra
nching enzyme. Previous studies have shown that core 2 beta1-6-N-glucosamin
yltransferase (C2GlcNAcT-I; EC 2.4.1.102) is required for functional modifi
cation of PSGL-1, the leukocyte P-selectin ligand, but have been ambiguous
on whether this enzyme is involved in E-selectin ligand formation. Using an
attachment and rolling assay under defined shear flow in vitro, this study
shows that C2GlcNAcT-I- lymphoid cells stably transfected with FucT-VII co
mplementary DNA attach and roll well on E-selectin at 1.5 dynes/cm.(2) Furt
her, attachment and rolling on P-selectin of neutrophils is sharply reduced
and that of short- term polarized Th1 cells is virtually abolished, with l
eukocytes from C2GlcNAcT-I-/- mice. In contrast, both neutrophils and Th1 c
ells from C2GlcNAcT-I-/- mice attach and roll as well as wild-type cells on
E-selectin. These results show that C2GlcNAcT-I is selectively required fo
r biosynthesis of ligands for P-selectin, but is not essential for at least
some E-selectin ligands, Distinct requirements for C2GlcNAcT-I in the form
ation of ligands for E-selectin versus P-selectin represents a novel level
of regulation of expression of selectin ligands and lymphocyte traffic.