Fig 2: Effect of curcumin and the miR33a inhibitor on ABCA1 (A) protein and (B) mRNA expression levels (n=3 per group). *P<0.05 vs. the control group; #P<0.05 vs. the foam cell model group; &P<0.05 vs. the curcumin group; *P<0.05 vs. the miR33a inhibitor group. ABCA1, ATP binding cassette transporter A1; miR, microRNA; ox-LDL, oxidized low-density lipoprotein.

Fig 3: Effects of curcumin on the (A) mRNA and (B) protein expression levels of ABCA1 in THP-1 macrophages (n=3 per group). *P<0.05 vs. the control group; #P<0.05 vs. the foam cell model group. ABCA1, ATP binding cassette transporter A1; ox-LDL, oxidized low-density lipoprotein.

Fig 4: Lack of Fdxr, Trp53, or both leads to altered lipid metabolism though the ABCA1–SREBP pathway in MEFs.A The levels of ABCA1, SREBP1/2, MVD, MVK, and actin were measured in WT, Fdxr+/−, Trp53+/−, and Fdxr+/−;Trp53+/− MEFs cultured in serum-free media for 4 h. B WT, Fdxr+/−, Trp53+/−, and Fdxr+/−;Trp53+/− MEFs were cultured in serum-free media for 8 h and then were stained with Nile Red (ex: 488 nm, em: 565 nm). DAPI (ex: 358 nm, em: 461 nm) was used to stain nuclei. C Quantitative measurement of intracellular cholesterol. WT, Fdxr+/−, Trp53+/−, and Fdxr+/−;Trp53+/− MEFs were cultured in a 96-well plate. After 4 h of fasting, the level of total cholesterol was measured with Cholesterol/Cholesterol Ester-GloTM assay kit according to the manufacturer’s instruction. Data represent the mean ± SD. D Quantitative measurement of intracellular triglyceride. WT, Fdxr+/−, Trp53+/−, and Fdxr+/−;Trp53+/− MEFs were cultured in a 96-well plate. After 4 h of fasting, the level of total triglycerides was measured with Triglyceride-GloTM assay kit according to the manufacturer’s instruction. Data represent the mean ± SD.

Fig 5: Mice deficient in Fdxr, Trp53, or both are prone to lipid accumulation in the blood.A The levels of ABCA1, SREBP1/2, MVD, MVK, and actin were measured in WT, Fdxr+/−, Trp53+/−, and Fdxr+/−;Trp53+/− mouse liver tissues. B–E The levels of blood cholesterol (B), triglycerides (C), LDL (D), and HDL (E) in 43-week-old WT, Fdxr+/−, Trp53+/−, and Fdxr+/−;Trp53+/− mice (n = 5). Values are mean ± SEM and analyzed by 2-tailed t-test.