Novel Cell-Based Assay to Investigate Monoacylglycerol Acyltransferase 2 Inhibitory Activity Using HIEC-6 Cell Line

The dietary triacylglycerol (TAG) gets absorbed and accumulated in the body through the monoacylglycerol (MAG) pathway, which plays a major role in obesity and related disorders. The main enzyme of this pathway, monoacylglycerol acyltransferase 2 (MGAT2), is considered as a potential target for developing antiobesity compounds. Hence, there is a need for in vitro cell-based assays for screening the potential leads for MGAT2 inhibitors. Because of synthetic inhibitor's side effects, there is an increased interest in natural extracts as potential leads. Hence, we have optimized a 2-MAG-induced TAG accumulation inhibitory cell-based assay to screen natural extracts using the HIEC-6 cell line. A concentration-dependent TAG accumulation was observed when the HIEC-6 cells were fed with exogenous 2-MAG. The TAG accumulation was confirmed by in situ BODIPY staining and was quantified. However, no TAG accumulation was seen when the cells were fed with exogenous DAG or TAG, suggesting MGAT2-mediated MAG uptake and its conversion to TAG. We demonstrated the utility of this assay by screening five different plant-based aqueous extracts. These extracts showed various inhibition levels (25% to 30%) of 2-MAG-induced TAG accumulation in the HIEC-6. The MGAT2 inhibitory potential of these extracts was confirmed by an in vitro MGAT2 assay. This cell-based assay adds a new methodology for screening, developing, and evaluating MGAT2 inhibitors for addressing obesity and related disorders.