Fucosyltransferases in Mucosal Immunity: Probing Function and Innovating Tools to Define Novel Substrates - Project Summary The long-term goal of this research program is to define how fucosyltransferases (FUTs) regulate immunity and tolerance in mucosal epithelial tissues. The mucosal epithelium lines the body's canals and organs in the digestive, respiratory and reproductive systems, and occupies an area ~200 times greater than skin, making it the body's largest protective barrier. Glycans are overlooked regulators of the mucosa that play an essential role mucosal immunity. On the mucosal epithelial cell surface, glycolipids and glycoproteins display covalently linked carbohydrate modifications (glycans) that vary in composition, length, and degree of branching. Fucosylation, i.e., the addition of fucose to glycans, is a highly regulated terminal `capping' reaction that influences glycan structure, length, and function. Nine fucosyltransferases, responsible for catalyzing the linkage-specific transfer of fucose to glycoproteins and glycolipids, have been described in humans. Individuals with FUT-inactivating polymorphisms exhibit unique patterns of susceptibility and resistance to viral infections, have distinct microbiomes, experience higher incidence of mucosal malignancies involving immune evasion, and have higher rates of inflammatory diseases including Crohn's, celiac, and inflammatory bowel disease, compared to those with wild type FUTs. Despite the critical role that FUTs play in normal physiology and disease, there is a significant gap in knowledge regarding their molecular function and regulation in mucosal epithelia. Through a multidisciplinary research program that leverages strengths in biochemistry, functional glycoproteomics, and cell biology, we aim to elucidate the molecular mechanisms involved in the regulation of immunity/tolerance in mammalian cells by FUTs. Of particular interest, is the role of FUTs in creating heterogeneous fucosylated glycan structures, and the role of glycan-binding proteins in recognition of these structures, to regulate tissue-resident and circulating immune cells. Over the next five years, my laboratory will leverage our historic strengths in the study of glycan structure, function, and regulation to achieve the following goals and understand: (1) how FUTs regulate mucosal immune cell populations to influence immunity and tolerance, (2) how glycan-binding proteins on immune cells recognize fucosylated sugars on mucosal epithelia, and (3) how difficult-to-characterize FUT substrates can be revealed by the development of a novel toolkit using glycosidase- and fucose marker-ion assisted ion mobility spectrometry-mass spectrometry. The vision of this research program is to significantly advance knowledge of novel fucosyltransferase-driven mechanisms that regulate tissue-resident and recruited mucosal immune cell populations, and spur new therapeutic strategies to treat human diseases arising from dysregulated mucosal immunity and tolerance.
