Development of a luciferase reporter Jurkat cell line under the control of endogenous interleukin-2 promoter

During new drug development, it is critical to have a cell-based reporter bioassay to measure drug-mediated physiological changes. In a conventional reporter cell line, a reporter expression construct is randomly inserted into the host cell genome with the reporter gene under control of an engineered promoter. This design ensures high signal output but may not represent the true physiological cell signaling. Here we used the CRISPR/Cas9 technology to engineer a Jurkat cell line by replacing one interleukin 2 (IL2) allele with firefly luciferase gene while keeping the other IL2 allele intact. The expression of luciferase is thus under control of endogenous IL2 promoter. We demonstrated that, in this engineered cell line, the IL-2 secretion pathway remained intact and luciferase activity significantly increased upon stimulation with phorbol ester or CD3/CD28 antibodies. We next expressed glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) in this cell line and observed dose-dependent IL-2 and luciferase responses to GITR agonist antibody. Thus we have successfully constructed a reporter cell line by engineering a reporter gene under control of an endogenous target gene promoter. This novel strategy may provide a more physiologically relevant alternative to the traditional method of reporter cell line construction.