The secretion of apolipoprotein B (apoB) by liver cells is an important determinant of the plasma concentrations of apoB, cholesterol, and LDL cholesterol. An important nutritional question is: Do unsaturated (USAT) and saturated (SAT) fatty acids (FA) influence apoB secretion similarly? HepG2 cells were incubated for 2-hours in serum-free medium with oleic or palmitic acids complexed to 0.15% hydroxypropyl-β-cyclodextrin (CD) or with oleic acid complexed to 1.5% bovine serum albumin (BSA). Uptake of 100 μM of [3H]-oleic acid/CD was much greater than uptake of 100 μM [3H]-palmitic acid/CD or uptake of 100 μM of [3H]-oleic acid/BSA. Triglyceride mass (μg/mg cellular protein) was significantly greater after 2 hour incubation with 100 μM oleic acid/CD (52.4 ± 88 (± SD)) compared to 100 μM palmitic acid/CD (30.3 ± 1.9) or 100 μM oleic acid/BSA (22.3 ± 1.2). ApoB secretion was measured after incubation for 1 hour with individual fatty acids/ 0.15% CD in serum-free medium by labeling with [3H]leucine and immunoprecipitation ApoB secretion was stimulated maximally (to about 30% of apoB synthesized) by 25-50 μM of oleic acid. However, equivalent stimulation of apoB secretion by palmitic acid was observed only at 100 μM. Similar results were obtained with other USAT (elaidic, linoleic, conjugated linoleic) and SAT FA (lauric, stearic acids) CD-delivered oleate stimulated apoB secretion to a greater extent than BSA-delivered oleate. The differences in concentration dependence between USAT and SAT FA in ability to stimulate apoB secretion appeared to be due to differences in FA uptake.
|Original language||English (US)|
|State||Published - 1997|
ASJC Scopus subject areas
- Molecular Biology