Adipophilin antisense oligonucleotides decrease ACAT activity

AIM: Based on the finding of adipophilin expression with the increase in cellular cholesterol, the aim of the present study was to look for the active site of adipophilin in cellular cholesteryl metabolism. METHODS: Mouse peritoneal macrophages were incubated with 80 mg/L Ox-LDL (Ox-LDL group) or 80 mg/L Ox-LDL plus 1 mmol/L adipophilin antisense oligonucleotides (Ox-LDL+antisense group), respectively. At the various time points, the incubated cell samples were observed with adipophilin immunofluorescence staining, flow cytometric analysis and cellular cholesterol analysis. RESULTS: The Ox-LDL+antisense group cells contained significantly lower cholesteryl ester (19.9±1.9) mg/g (protein) than that of cells in Ox-LDL group (46.6±3.4) mg/g (protein) at 4 days. From 12 h, expression of adipophilin in Ox-LDL group increased more quickly than that of the cells in Ox-LDL+antisense group. At day 4, the level of adipophilin expression in Ox-LDL group was significantly higher than that in Ox-LDL+antisense group. During the observation, the amount of Ox-r［CL-3H］ LDL taking up increased gradually in both groups, however, from day 1 the taking up amount in Ox-LDL+antisense group was less than that in Ox-LDL group. There was a statistical difference between the two groups from day 2 to day 4. From 6 h to day 2, the relative ACAT activity increased in both groups. The relative ACAT activity kept unchanged from day 2 to day 4 in the two groups. At day 2, the relative ACAT activity in Ox-LDL+antisense group was significantly lower than that in Ox-LDL group. Correlative analysis between activity of ACAT and adipophilin expression showed than R2 were 0.6176 and 0.8212 (P<0.05) in Ox-LDL group and Ox-LDL+antisense group, respectively. CONCLUSION: At least partly, expression of adipophilin is related to cellular taking up of lipoproteins and to ACAT activity. Therefore, the results indicate that adipophilin has a role in metabolism of cellular lipid droplets and the effective point may be ACAT.