GlcNAc-transferase V and core 2 GlcNAc-transferase expression in the developing mouse embryo.

UDP-GlcNAc:Manalpha1-6Manbeta-R beta1-6-N-acetylglucosaminyltransferase V (GlcNAc-TV) and UDP-GlcNAc:Galbeta1-3GalNAc-R beta1-6-N-acetylglucosaminyltransferase (core 2 GlcNAc-T) are Golgi enzymes that catalyse the biosynthesis of beta1-6GlcNAc-branched intermediates in the N- and O-linked biosynthesis pathways, respectively. The activities of these enzymes change during haematopoiesis, embryo-carcinoma cell differentiation and following malignant transformation, but little is known about their expression in normal adult tissues and during embryogenesis. We have examined the expression of GlcNAc-TV and core 2 GlcNAc-T in sections of post-implantation mouse embryos by in situ RNA hybridization. The two enzymes showed distinct temporal and spatial patterns of expression. Core 2 GlcNAc-T mRNA was widely expressed at embryonic day (E) 7, and became restricted to a subset of mucin- and cartilage-producing tissues at E11.5 through to E17.5. GlcNAc-TV transcripts were absent at E7, became expressed throughout E9.5 embryos, and then progressively restricted to regions of the developing central nervous system and to specialized epithelia of skin, intestine, kidney, endocrine tissues and respiratory tract. In the adult gonads, GlcNAc-TV transcripts were excluded from germ cells, but were detected in the follicular and testicular cells. Leukoagglutinin (L-PHA)-reactive oligosaccharides co-localized with GlcNAc-TV transcripts in skin, kidney and intestine, but brain showed unexpectedly low overall staining punctuated by bright staining of the vascular endothelium. A common feature of cells in basal epithelia and in the cortical neural epithelium is the capacity to migrate, a cellular function which may require GlcNAc-TV-dependent glycoconjugates.