Mapping the Expressed Glycome and Glycosyltransferases of Zebrafish Liver Cells as a Relevant Model System for Glycosylation Studies

Abstract

The emergence of zebrafish as a model organism for human diseases was accompanied by the development of cellular model systems that extended the possibilities for <i>in vitro</i> manipulation and <i>in vivo</i> studies after cell implantation. The exploitation of zebrafish cell systems is, however, still hampered by the lack of genomic and biochemical data. Here, we lay a path toward the efficient use of ZFL, a zebrafish liver-derived cell system, as a platform for studying glycosylation. To achieve this, we established the glycomic profile of ZFL by a combination of mass spectrometry and NMR. We demonstrated that glycoproteins were substituted by highly sialylated multiantennary <i>N</i>-glycans, some of them comprising the unusual zebrafish epitope Galβ1–4­[Neu5Ac­(α2,3)]­Galβ1–4­[Fuc­(α1,3)]­GlcNAc, and core 1 multisialylated <i>O</i>-glycans. Similarly, these analyses established that glycolipids were dominated by sialylated gangliosides. In parallel, analyzing the expression patterns of all putative sialyl- and fucosyltransferases, we directly correlated the identified structures to the set of enzymes involved in ZFL glycome. Finally, we demonstrated that this cell system was amenable to metabolic labeling using functionalized monosaccharides that permit <i>in vivo</i> imaging of glycosylation processes. Altogether, glycomics, genomics, and functional studies established ZFL as a relevant cellular model for the study of glycosylation