Fig. 6.
Role of SR-BI in nascent HDL particle formation and cholesterol efflux in primary hepatocytesm. Primary hepatocytes from SR-BI+/+ and SR-BI−/− mice were treated with or without LXR agonist T0901317 (5 µM) for 16 h, and then with or without glyburide (500 µM) for 1 h. Cells were then incubated in the presence or absence of glyburide with 20 µg/ml lipid-free human apoA-I for 16 h. A: ABCA1 and SR-BI expression were determined by Western blot analysis. Hepatocytes were labeled with 0.2 µCi/ml [3H] cholesterol for 48 h. Cells were treated with T0901317 and glyburide as indicated. B: Following incubation with 20 µg/ml lipid-free human apoA-I for 16 h, radioactivity in the medium and cells was determined. Cholesterol efflux was calculated as the percentage of counts in the medium relative to the total counts in the medium and cells together. Values shown were the mean ± SEM of triplicate determinations. C: ApoA-I lipidation was assessed by separating cell culture medium (5 µl) by nondenaturing GGE and immunoblotting with anti-human apoA-I. Results are representative of two experiments. Significance at *: P < 0.05; ***: P < 0.001.