O-linked glycans in drosophila development: Overview

O-linked glycosylation is the addition of carbohydrate residues to serine or threonine on target proteins. Identification of mutations in the enzymes responsible for O-glycosylation in several human diseases and studies in model organisms have shown that O-glycans play important roles in animal development and physiology. Drosophila is an important genetic model system to study the developmental roles of various glycans. After providing a brief overview of the types of O-glycans identified on Drosophila proteins, this chapter describes the function of two conserved forms of O-glycan, namely, O-mannose and mucin-type O-GalNAc glycans, in Drosophila development. O-mannose modifications are found on the transmembrane protein dystroglycan and are critical for its function, as mutations in the protein O-mannosyltransferases cause human dystroglycanopathies. Mucin-type O-glycosylation, defects in which are implicated in a number of human diseases, also plays critical roles in the development of several fly organ systems such as gut, wing, respiratory system, and the embryonic mesoderm. Future studies in Drosophila are likely to further elucidate the role of O-glycosylation in animal development and might provide insight into the pathophysiology of human diseases caused by alteration in O-glycosylation.