Fig 2: Inhibition of steatosis by Hdac1 knockdown in HepG2 cells. (A) Hdac1 shRNA transfection. HepG2 cells were electrical transfected with Hdac1 shRNA plasmid or control vector using cell line nucleofector Kit L, program T031. Pictures were taken using a microscopy with 10 × object lenses for transfection efficiency. Scale bar: 200 μm. (B) Impact of Hdac1 knockdown in steatosis. Oil red staining of triglyceride in transfected HepG2 cells after 0.5 mmol/L oleic acid treatment for 24 h. Scale bar: 100 μm. (C) Triglyceride quantification in the knockdown cells. (D) Suppression of lipogenic proteins by Hdac1 knockdown or chemical inhibitor. Western blot of HDAC1, HDAC3, SREBP1, SCD1, PPARγ protein in HepG2 cells after 0.5 mmol/L oleic acid treatment for 24 h. In the first column, Hdac1 was knocked down by shRNA. In the second column, HDAC1 was inhibited with HDAC1-specific inhibitor (0.4 mmol/L) for 30 min before oleic acid treatment in HepG2 cells. In the bar figure, each data represents mean ± SE (n = 3). *P < 0.05.

Fig 3: Reduction of HDAC1 protein in the liver of P50-KO mice. HDAC1 protein was decreased in the liver of P50-KO mice compared with that of WT mice. HDAC1 down-regulation was associated with the decrease in hepatic steatosis. (A) Nuclear protein in the liver tissue of P50-KO mice on chow diet. (B) Nuclear protein in the liver of P50-KO mice on HFD. (C) mRNA expression. mRNA level of HDAC1, HDAC3, SIRT1 was determined in the liver tissue of P50-KO mice on chow diet and HFD, respectively. (D) Proteins in liver tissue of WT mice on HFD. Western blot was performed for HDAC1, HDAC3, SIRT1, SCD1 and SREBP1 proteins in liver tissue of WT mice on HFD for 4 months. In the bar figure, each data represents mean ± SE (n = 8). *P < 0.05, **P < 0.01.

Fig 4: Maintenance of HDAC1 protein level was dependent on P50. MEF cells with P50-KO, IκBα-KO and Ikkβ-KO were examined for HDAC1 after TNF-α (20 ng/mL) treatment at different times as indicated. The signal of HDAC1 protein was quantified and normalized with the signal of actin in the blot. (A) Liver gene expression. The expression was determined in the liver of P50-KO mice by qRT-PCR. (B) HDAC1 in the wild type MEF cells treated with TNF-α. (C) HDAC1 in the P50-KO MEF cells treated with TNF-α. (D) Blockage of HDAC1 reduction by proteasome inhibitor. HDAC1 protein was examined in P50-KO MEF cells that were pretreated with the proteasome inhibitor MG132 for 30 min followed by TNF-treatment for 120 min. (E) HDAC1 in the IκBα-KO MEF cells treated with TNF-α. (F) HDAC1 in the Ikkβ-KO MEF cells treated with TNF-α. Each experiment was repeated at least three times with consistent results. Representative blots were shown. In the bar figure, each data represents mean ± SE (n = 3). **P < 0.01.