Fig. 4.

p53 engages TIGAR and supports redox control in response to nutrient excess. (A) Analysis of TIGAR gene expression in the public transcriptomics dataset GSE135251 comparing a control group, patients with MASLD/MASH with low fibrosis scores (F0/F1), and patients with MASH with high fibrosis scores (F2–F4). n = 10 control, n = 85 F0/F1, and n = 121 F2–F4 samples. Data presented in transcripts per kilobase million (TPKM) and analysed using an ordinary one-way ANOVA with Holm-Sidak’s multiple comparisons test and multiplicity-adjusted p values. (B,C) Western blot analysis (B) and quantification (C) of TIGAR, CDKN1A/p21, and MDM2 expression in TP53 WT and TP53-deficient HepG2 cells cultured in baseline medium supplemented with BSA or HFHS medium formulation for 48 h n = 8 independent experiments. COXIV used as loading control. TIGAR abundance represents sum of bands. Protein MW ladder (in kDa) as depicted. Data presented as mean +/- SEM with data points and analysed by two-way ANOVA with Holm-Sidak’s multiple comparisons test and multiplicity-adjusted p values.

(D,E) Western blot analysis (D) and quantification (E) of TIGAR, p21, and MDM2 expression in Trp53 WT Hep53.4 HCC cells as in (B,C). n = 7 independent experiments. Data presented and analysed as in (B,C). (F) Analysis of ROS (CellROX Deep Red) via flow cytometry in TP53 WT and TP53 KO HepG2 cell lines cultured in same media formulations as (B,C). n = 5 independent experiments. Data presented as MFI relative to WT BSA treatment with individual data points per experiment. Data analysed as in (C).

(G,H) Analysis of ROS (CellROX Deep Red) via flow cytometry in HepG2 (G) or Hep53.4 (H) cells treated with either non-targeting control (NT) or siRNA against TP53/Trp53 (p53) or TIGAR/Tigar (TIG) for 96 h and cultured as in (B/C). n = 7 independent experiments for (G). Data from n = 7 experiments for NT and Trp53 siRNA and n = 3 for Tigar siRNA for (H). Data presented and analysed as in (F). (I,J) Western blot analysis (I) and quantification (J) of TIGAR expression in liver lysates created from Trp53^WT (WT) and Trp53^livΔ (FL) mice after 1 year of HFHS diet or control (chow) (as in Fig. 2). n = 4 Trp53^WT chow-fed mice, n = 6 Trp53^WT HFHS-fed mice, n = 6 Trp53^livΔ chow-fed mice and n = 7 Trp53^livΔ HFHS-fed mice. ACTIN used as loading control. TIGAR abundance represents sum of bands. Protein MW ladder (in kDa) as depicted. Data presented and analysed as in (C), comparing TIGAR expression between chow and HFHS samples within each liver Trp53 group. (K) Representative H&E images and staining for MDA in female Lepr^db/db (db/db; Tigar^WT) and Lepr^db/db; Tigar^-/-(db/db; Tigar^-/-) mice at 100 days of age. Mice were either provided with normal water throughout or treated with NAC in the drinking water ad libitum from 42 days of age (+NAC). Representative of n = 6 Tigar WT; db/db and n = 10 Tigar^-/-; db/db mice on normal water and n = 8 NAC-treated mice per cohort. Scale bars 20 μm. (L) Quantification of MDA to assess lipid peroxidation in mice from (K). N-numbers as in (K). WT: db/db; Tigar^WT, KO: db/db; Tigar^-/-, CHOW: mice with normal drinking water, +NAC: mice treated with NAC drinking water. Data presented and analysed as in (B/C).

n.s., not significant, ∗p <0.05 ∗∗p <0.01, ∗∗∗p <0.001, ∗∗∗∗p <0.0001. HFHS, high-fat and high-sugar; KO, knockout; MDA, malondialdehyde; MFI, median fluorescence intensity; MW, molecular weight; NAC, N-acetyl-cysteine; ROS, reactive oxygen species; siRNA, small-interfering RNA; WT, wild-type.