FIGURE 4.
Chemical inhibition of MTP decreases cholesteryl esters in cultured cells. A–F, differentiated Caco-2 cells were pulsed from the apical side with 1 μCi/ml [3H]OA for 17 h, washed, and then chased for 24 h with 1.6 mm OA and 0.5 mm taurocholate in the presence or absence of BMS200150 (10 μm). The basolateral medium was used to measure apoB (A) and apoAI (B). The medium and cells were used to extract lipids and to quantify secreted and cellular [3H]triglyceride (C and D) and cholesteryl esters (E and F), respectively. Each experiment was performed in triplicate, and the data are representative of two independent experiments. G–I, HepG2 cells were labeled with 1 μCi/ml [3H]cholesterol for 17 h; washed; and then chased with OA·BSA complexes with or without 1 μm BMS200150, BMS192951, or BMS197636 for 24 h. ApoB and apoAI levels were measured in the medium to determine the effects of these inhibitors on secretion (G and H). Lipids were extracted from the cells and used to quantify radiolabeled cholesteryl esters (I). J and K, AC29 cells stably transfected with either ACAT1 or ACAT2 were labeled with [3H]cholesterol and chased with OA (0.2 mm)·BSA (0.5%) complexes with or without BMS197636 (1 μm) or 148817 (1 μm) for 17 h. Lipids were extracted from the cells and used to quantify [3H]cholesteryl esters). L–N, differentiated Caco-2 cells were pulsed with 1 μCi/ml [3H]cholesterol for 17 h; washed; and then chased with 1.6 mm OA and 0.5 mm taurocholate in the presence or absence of 1, 5, or 10 μm 148817, BMS197636, or both inhibitors. The basolateral medium was used to measure apoB (L) and apoAI (M). Lipids were extracted from cells and used to quantify [3H]cholesteryl esters (N). The results are plotted as a percent of the control. Each experiment was done in triplicate, and the data are representative of three independent experiments. **, p < 0.01; ***, p < 0.001.