Fig. 5.

Increased TG secretion in ABCA1 silenced McA cells is attenuated by nascent HDL-containing conditioned medium. Conditioned McA medium (+ McA CM) was prepared by incubating 10 μg/ml of apoA-I with McA cells for 24 h; nonconditioned medium (− McA CM) was prepared by incubating the same concentration of apoAI in empty dishes. Conditioned or nonconditioned medium was then transferred to McA cells that had been previously transfected with control or ABCA1 siRNA and cells were then stimulated with 0.4 mM oleate in serum-free radiolabeling medium (containing 5 μCi/ml [³H]oleate) for an additional 12 h. Cells were harvested for Western blot analysis (A) and the medium was harvested to determine the extent of [³H]oleate incorporation into secreted TG (B). A: ABCA1 and p-PI3K p85/p55 expression by Western blot analysis. NS, non-specific band used as load control. B: [³H]TG secretion from control or ABCA1 siRNA-treated McA cells after incubation with conditioned medium from McA cells or nonconditioned medium for 12 h. Results are representative of two separate experiments and are expressed as mean ± SEM of triplicate analyses. * (P < 0.05), ** (P < 0.01), *** (P < 0.001) by Student's t-test.