Roles of HNK-1 carbohydrate epitope and its synthetic glucuronyltransferase genes on migration of rat neural crest cells.

HNK-1 carbohydrate epitope is localized on the surface of avian neural crest cells (NCCs), and is necessary for their migration. However, it is still disputed whether the epitope works in similar ways in mammalian embryos. In this study, we found that HNK-1 carbohydrate epitope was specifically detected in some of the cranial ganglia, migrating trunk NCCs and some non-NCC derivatives in the rat embryo. Two genes encoding glucuronyltransferases that synthesize the HNK-1 epitope in vitro (GlcAT-P and GlcAT-D) were recently identified in the rat. Interestingly, the NCCs in the cranial ganglia expressed the GlcAT-D gene, whereas the migrating trunk NCCs expressed the GlcAT-P gene. To investigate in vivo functions of the GlcATs in the NCC migration further, we overexpressed GlcAT genes by electroporation in the cranial NCCs in cultured rat embryos. Transfection of both GlcAT genes resulted in efficient synthesis of the HNK-1 epitope in the NCCs. GlcAT-P overexpression increased distance of cranial NCC migration, whereas GlcAT-D overexpression did not show this effect. Our data suggest that the HNK-1 epitope synthesized by different GlcATs is involved in migration in the sublineages of the NCCs in the rat embryo, and that GlcAT-P and GlcAT-D mediate different effects on the NCC migration.