A Facile Method for Screening DPP IV Inhibitors in Living Cell System Based on Enzyme Activity Probe

Dipeptidyl peptidase IV (DPP IV), one of the most essential peptidase, is widely distributed in various organs and tissues of the human body, which affects protein stability by acting on peptide bonds at the end of peptide chains and is further involved in physiological processes such as cellular metabolism and signaling. Recent studies have shown that DPP IV is not only involved in normal physiological processes but also closely related to various pathological processes, making it an important target for the treatment of metabolic diseases. Deciphering the relevance of DPP IV to human diseases and screening the inhibitors of DPP IV requires reliable tools, which can sense the function of this key enzyme in complex biological samples. Therefore, we aimed to construct a simple and easy-to-use assay for human DPP IV activity in a living cell system to achieve highly sensitive and selective detection of DPP IV function and further screening for its inhibitors. An easy-to-use assay for DPP IV function at the cellular level with a specific fluorescence probe toward DPP IV using a fluorescence microplate reader was the first to be established. Then, the experimental conditions were systematically optimized in terms of cell density, concentrations of probe, and incubation time. After that, the efficacy of the positive DPP IV inhibitors was evaluated by utilizing the optimized easy-to-use assay. Overall, this easy-to-use assay exhibited good precision, robustness, high throughput, and reliability. In conclusion, a straightforward and user-friendly method has been developed for detecting DPP IV activity in live cells, enabling accurate assessment of DPP IV function and efficient screening of inhibitors. This method may hold significant implications for advancing understanding of the relationship between DPP IV and disease progression, early disease diagnosis, and personalized drug therapy.