Location: Exhibit/Poster Hall A-B - Pennsylvania Convention Center
Poster Board Number: A450
Mirat Sojitra (University of Alberta), Susmita Sarkar (University of Alberta ), Jasmine Maghera (University of Alberta ), Edward Schmidt (University of Alberta ), Emily Rodrigues (University of Alberta ), Eric Carpenter (University of Alberta ), Shaurya Seth (University of Alberta ), Daniel Vinals (University of Alberta ), Nicholas Bennett (University of Alberta ), Revathi Reddy (University of Alberta ), Amira Khalil (University of Alberta ), Xiaochao Xue (University of Alberta ), Michael Bell (University of Alberta ), Ruixiang Zheng (University of Alberta ), Ping Zhang (University of Calgary), Corwin Nycholat (The Scripps Research Institute), Justin Bailey (University of Alberta ), Chang-Chun Ling (University of Calgary), Todd Lowary (University of Alberta , Institute of Biological Chemistry, Academia Sinica, Institute of Biochemical Sciences, National Taiwan University), James Paulson (The Scripps Research Institute), Matthew Macauley (University of Alberta , University of Alberta), Ratmir Derda (University of Alberta )
Abnormal cell surface glycosylation plays a major role in disease processes such as immune evasion. However, the underlying role of glycans is yet to be fully understood. Binding information obtained from glycan arrays can provide critical starting points for downstream applications such as the development of carbohydrate-based inhibitors, vaccines, and other therapeutics. However, it is challenging to use powerful techniques like DNA deep sequencing to analyze glycan recognition due to the lack of 1:1 correspondence between DNA and glycan structures. Therefore, we have developed Liquid Glycan Array (LiGA), a technology that allows for genetic encoding of glycans. LiGA provides a 1:1 correspondence between the glycan displayed in multiple copies on a bacteriophage carrier and the phage genetic material. LiGA is generated by acylation of phage pVIII protein with a dibenzocyclooctyne, followed by ligation of azido-modified glycans. The display of glycans on each phage virion can be controlled from 30-1500 copies to probe the critical variables in glycan recognition: valency and density. A simple pulldown of the LiGA along with lectins followed by deep sequencing of the DNA in the bound phage decodes the recognized glycans. LiGA is target agnostic and measures binding profile of lectins expressed on intact cells, such as hCD22 (Siglec-2) and DC-SIGN (Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin), and in live mice (Nat. Chem. Bio. 17, 806–816, 2021). From a mixture of 50-100 multivalent glycan probes, LiGA identifies the glycan-phage conjugates with optimal valency and density for binding to antibodies and lectins on cells in vitro and in vivo.
Sialic acid-binding immunoglobulin-type lectins (Siglecs) expressed on the surface of immune cells are exploited by cancer to evade immune response. We applied LiGA to study the binding specificity of Siglec-7, a cell surface receptor that cancer cells use to evade immune response from natural killer (NK) cells. Additionally, we explored the roles of valency and density in ganglioside interaction with Siglec-1 using a cell-based assay. Building on these successes, we plan to use LiGA to identify the valency and affinity required by trans- glycan to overcome the cis- masking on the surface of immune cells.
