obese (DIO) rats: (0.3, 1, and 3 mg/kg, PO, qd) during a 21-day

The ability of T863 to inhibit DGAT activity was investigated in intact cells using HEK293 cells overexpressing human DGAT1 (HEK293-DGAT1). Compared with control HEK293 cells, HEK293-DGAT1 cells have increased hDGAT1 protein, increased in vitro DGAT activity, and increased incorporation of 14C-labeled oleate into TAG; all of these phenotypes can be reversed by siRNA-mediated knockdown of hDGAT1 in these cells, demonstrating dependence on hDGAT1. T863 caused a dose-dependent inhibition of cellular TAG formation in HEK293-DGAT1 cells, with an IC50 of 122 nM. Interestingly, in contrast to the decreased TAG formation, formation of phosphatidylcholine was increased by T863. This increase in phosphatidylcholine synthesis is probably due to increased flux of fatty acyl-CoA and DAG to the phospholipid biosynthesis pathway in the face of DGAT1 inhibition, as has been observed previously in the reverse direction in fibroblasts overexpressing DGAT1. Collectively, the studies demonstrated that T863 is a potent, selective, and cell-permeable DGAT1 inhibitor.