UC Irvine

DNA-encoded library (DEL) technology is a powerful next-generation drug discovery engine. DELs permit the design and synthesis of large, customized molecular libraries, which can be mined for new ligands by affinity selection. More advanced screening technology has emerged that enables direct activity-based DEL screening, but to date, this is limited to biochemical activity assays. Cellular assays, which are vital for discovering physiologically relevant novel chemical matter, are still incompatible with DEL. Here, I describe a prospective workflow that renders DEL compatible with cellular activity assays. Cells are grown directly on DEL beads, which effectively serve as microcarriers. The cells are engineered to secrete a reporter upon stimulation with an agonist, which is liberated from the DEL bead via photocleavage. The microcarrier is functionalized with affinity tag ligands, which capture the affinity-tagged secreted reporter. Toward this goal, I have engineered cell lines that secrete HaloTag-labeled fluorescent protein reporters, shown that reporter cell lines can grow and signal on microcarriers, and explored photocleavage conditions that permit efficient photochemistry while preserving cell viability. Additional studies were conducted to identify appropriate positive control ligands of a model cellular target, STING (stimulator of interferon genes). This thesis lays the groundwork for a DEL-compatible cellular assay paradigm that can be adapted to an array of cell-based assay strategies.