Function and regulation of epithelial glycosylation

Summary/abstract This research program focuses on uncovering the biological roles of glycoconjugates. Part of this effort is devoted to the development of chemical biology tools for glycoscience research. In the past, we have developed photocrosslinking sugar analogs that can be incorporated into cellular glycoconjugates and used to covalently crosslink glycoconjugates to their binding partners in a native context. These reagents can be used to identify glycan-dependent binding interactions, and to characterize where and under what conditions that these interactions occur. Over the next five years, we will further expand the scope of experiments that can be performed by preparing additional photocrosslinking sugars, developing new methods for their incorporation, and evaluating their incorporation into additional glycoconjugates. Using one of these photocrosslinking sugars, we made the unexpected observation that cholera toxin can bind fucosylated glycoconjugates in addition to its canonical receptor, the ganglioside GM1. Over the next five years, we will determine the molecular structure of fucosylated glycoconjugates recognized by cholera toxin and characterize their role in host cell intoxication. These studies are supported by our long-term collaboration with the Yrlid group (University of Gothenburg) and their expertise in studying cholera disease mechanisms. Our studies of cholera toxin receptors led us to become interested in the diverse glycoconjugates that line the intestinal and respiratory epithelia. A CRISPR screen designed to identify genes that modulate cholera toxin binding to cell surfaces identified a number of candidate genes that may function in the regulation of glycosylation by diverse mechanisms. Over the next five years, we will characterize novel regulators of glycosylation and determine how they shape the glycome, modulating glycan features such as polyLacNAc chain length and the degree of fucosylation. The long-term goal of these studies is to determine how glycan features vary among individuals, their association with disease states, and their impact on host-microbe interactions.