Expression of three Caenorhabditis elegans N-acetylglucosaminyltransferaseI genes during development

UDP-N-acetylglucosamine:alpha-3-D-mannoside beta-1,2-N-acetylglucosaminyltr ansferase I (GnT I) is a key enzyme in the synthesis of Asn-linked complex and hybrid glycans. Studies on mice with a null mutation in the GnT I gene have indicated that N-glycans play critical roles in mammalian morphogenesi s. This paper presents studies on N-glycans during the development of the n ematode Caenorhabditis elegans, We have cloned cDNAs for three predicted C. elegans genes homologous to mammalian GnT I (designated gly-12, gly-13, an d gly-14), All three cDNAs encode proteins (467, 449, and 437 amino acids, respectively) with the domain structure typical of previously cloned Golgi- type glycosyltransferases. Expression in both insect cells and transgenic w orms showed that gly-12 and gly-14, but not gly-13, encode active GnT I. Al l three genes were expressed throughout worm development (embryo, larval st ages L1-L4, and adult worms). The gly-12 and gly-13 promoters were expresse d from embryogenesis to adulthood in many tissues. The gly-14 promoter was expressed only in gut cells from L1 to adult developmental stages. Transgen ic worms that overexpress any one of the three genes show no obvious phenot ypic defects. The data indicate that C. elegans is a suitable model for fur ther study of the role of complex N-glycans in development.