Research:

Protein N-glycosylation in Growth and Development
Modification of proteins with N-glycans (N-glycosylation) is critical for a number of developmental and physiological processes in all eukaryotes. Our work focuses on the role of protein N-glycosylation in cell function and tissue development. Protein N-glycosylation is initiated by the ALG7 gene that functions at the first committed step in the synthesis of the lipid-linked oligosaccharide (LLO) precursor and is a key regulator LLO abundance in vivo. To determine how ALG7 regulates cell function we have examined the consequences of inappropriate expression of ALG7 in the yeast Saccharomyces cerevisiae. Yeast cells with disregulated ALG7 display perturbation of a number of signaling and metabolic pathways. To identify the downstream targets of ALG7, we have generated a mutant alg7 strain with a genomic hypomorphic allele of ALG7. This mutant is being used in a genetic screen to search for factor(s) affected by inappropriate protein N-glycosylation.
To further characterize the role of ALG7 in mammalian development, we are using the mouse submandibular gland (SMG) as a model. In the SMG, ALG7 is highly expressed during periods of active cell proliferation and it is downregulated with cellular differentiation. To determine how changes in ALG7 expression guide SMG development, we have focused on the relationships between ALG7 and E-cadherin, an N-glycosylated cell-cell adhesion receptor that plays pivotal roles in epithelial tissue development. We have shown that changes in ALG7 expression modulate the N-glycosylation status of E-cadherin and its adhesion dynamics during morphogenesis and differentiation. Our current studies focus on characterizing the roles of E-cadherin N-glycans in cell-cell adhesion during SMG organogenesis using perturbation approaches in SMG explant cultures ex vivo and in transgenic mice in vivo.