Grant: Project Grant

In this project, we will use genetically-encoded technology termed "liquid glycan array" (LiGA) to map carbohydrate-binding specificity of carbohydrate binding protein (CBP) that serve as immune cells receptors that govern cell-pathogen interaction and aid evasion of tumor by immune system. Carbohydrate-binding proteins (CBPs) play a critical role in immunology and cancer, yet there are no therapeutic drugs that block these proteins. For example, family of CBPs of therapeutic interest are Sialic acid-binding immunoglobulin-type lectins (Siglec). The 14 human Siglecs contribute to the process of the immune system by regulating the innate and adaptive immune responses via interactions with glycans on mammalian cells. The similar structure across the Siglec family complicates dissecting their role and discovering specific inhibitors of specific Siglec family members. The major barrier in studying the ligands for CBPs originates from the fundamental lack of one-to-one correspondence between sequence of DNA and structures of carbohydrates. The Central Dogma of Biology, DNA-RNA-Protein, allows studying DNA, RNA and proteins using a unified tool of next-generation DNA sequencing. Investigations of carbohydrates in biology relies on technology akin to a DNA microarray: a glycan array, made by printing carbohydrates on glass surface. It is not possible to apply the glycan array to study CBPs in their natural environment (e.g., the surface of the immune cells in vitro or in vivo). To solve this challenge, Derda Lab developed a genetically encoded "Liquid glycan array" (LiGA) by chemical attachment of carbohydrates to bacteriophage (phage) particles. Deep sequencing of DNA barcode inside the phage identifies the structure of carbohydrate attached to it. Using a simple pull-down and deep-sequencing, similar to those used in classical CHiPSeq technology, LiGA can be used to map glycan binding preferences of proteins, cells in vitro and even immune cell in vivo.