Macrophage ABCA1 and ABCG1, but not SR-BI, promote macrophage reverse cholesterol transport in vivo
J. Clin. Invest. Xun Wang, et al. 117:2216 doi:10.1172/JCI32057 [Go to this article.]

Figure 4
Knockdown of ABCG1 in J774 macrophages reduces cholesterol efflux in vitro and RCT in vivo. (A) Quantitative analysis of mRNA expression of abcg1 in ABCG1-KD and control cells by quantitative RT-PCR. Total RNA was extracted from cells that were treated with either vehicle or 1 μM GW3965 for 24 hours. Data are expressed as fold change ± SD and normalized to mouse 18S rRNA. (B) Western blotting demonstrating the knockdown of ABCG1 protein expression. Control and ABCG1-KD cells were treated with either acLDL or GW3965. ABCG1 was detected by Western blotting with anti-ABCG1 antibody. Equal amount of total proteins were loaded. Lanes 1, 3, and 5 represent control cells. Lanes 2, 4, and 6 represent ABCG1-KD cells. (C and D) Cholesterol efflux assay was performed as described in Figure 1 in the presence of HDL₃ (25 μg/ml) or 2.5% mouse whole serum for 4 hours. Data are expressed as mean ± SD; n = 3. **P < 0.01; ***P < 0.001. (E and F) The RCT experiment was performed as described in Figure 1 with [³H]cholesterol-labeled, acLDL-loaded, and LXR agonist–treated J774 control macrophages and ABCG1-KD macrophages. n = 8 mice per group. Data are expressed as the percentage of tracer relative to total cpm tracer injected ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001. Results are representative of 3 independent experiments. (E) Time course of [³H]cholesterol distribution in plasma. Individual time points and areas under the curve were determined and compared. (F) Fecal [³H]tracer levels. Feces were collected continuously from 0 to 48 hours.