Fig. 4: Replenishment of NO rescues the defective HIF-1α activation and its related glycolysis in MDM2 knockdown macrophages.

Mouse BMDM were transfected with siMdm2 or siScramble for 24 h, then stimulated with LPS and IFNγ for 20 h, followed by treatment with NO donor S-Nitroso-N-acetylpenicillamine (SNAP) or DMSO for 3 h. a Total nitrate and nitrite in the cell culture medium. n = 4. b Nuclear HIF-1α transcriptional activity in the BMDM. n = 4. c The treated cells were subjected to S-nitrosylation assay, followed by immunoprecipitation (IP) of HIF-1α. Immunoblotting analysis of HIF-1α in the nuclear extract and S-nitrosylated HIF-1α (labeled by iodoTMT Reagent) was performed using an HIF-1α antibody and anti-TMT antibody respectively. Lamin B1 is a nuclear protein and used as loading control. d GlycoPER was measured using Seahorse XF analyzer. The right panel is the area under curve (AUC). n = 5. P values of siScramble-LPS + IFNγ vs siMdm2-LPS + IFNγ are under the curve while siMdm2-LPS + IFNγ vs siMdm2-SNAP + LPS + IFNγ is above and highlighted in yellow. e Lactate in the cell culture supernatant. n = 4. f Relative mRNA levels of glycolytic genes normalized with β-actin and expressed as fold change over siScramble-LPS + IFNγ. n = 4. Data are displayed as mean ± SEM. Statistical significance was examined using one-way ANOVA with Tukey post-hoc test. N number represents the number of biological replicates. Representative immunoblot images are shown from at least two independent experiments.