Abstract
C. elegans is a well-defined and simple animal model for genetic dissection of the roles of O-linked glycoproteins in development. Polypeptide GalNAc transferases (ppGaNTases) are a family of enzymes in the Golgi apparatus that posttranslationally modify serine and threonine residues with an N-acetylgalactosamine sugar in proteins that are destined for the cell surface, extracellular matrix, or secretion. The C. elegans genome contains a total of nine genes that express thirteen glycosyltransferase mRNAs, all of which share significant sequence similarity and predicted structural topology with mammalian ppGaNTases. The size of this gene family suggests that, in animal cells, O-glycosylation of mucin-type protein sequences is regulated by tissue-specific distribution of different ppGaNTase isozymes.
To understand how the repertoire of glycosyltransferases changes in a cell-specific pattern during embryonic and juvenile development, we have constructed transgenic animals that express lacZ or GFP reporters for each member of the ppGaNTase family in C. elegans. Preliminary transgene expression data on the spatiotemporal expression of these isoforms suggests that differential distribution of ppGaNTase isoforms regulates the specificity and potential of O-glycosylation in the cell during development.
