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Iron metabolism regulates p53 signaling through direct heme-p53 interaction and modulation of p53 localization, stability, and function.

Shen J, Sheng X, Chang Z, Wu Q, Wang S, Xuan Z, Li D, Wu Y, Shang Y, Kong X, Yu L, Li L, Ruan K, Hu H, Huang Y, Hui L, Xie D, Wang F, Hu R - Cell Rep (2014)

Bottom Line: Iron excess is closely associated with tumorigenesis in multiple types of human cancers, with underlying mechanisms yet unclear.Strikingly, the iron polyporphyrin heme binds to p53 protein, interferes with p53-DNA interactions, and triggers both nuclear export and cytosolic degradation of p53.Moreover, in a tumorigenicity assay, iron deprivation suppressed wild-type p53-dependent tumor growth, suggesting that upregulation of wild-type p53 signaling underlies the selective efficacy of iron deprivation.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Molecular Biology, Chinese Academy of Sciences, 320 Yue-yang Road, Shanghai 200031, China; University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yue-yang Road, Shanghai 200031, China.

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Tumor Suppressor p53 Protein Is Downregulated in Iron Excess(A) Perls’ Prussian Blue staining of Hfe+/+ and Hfe−/− mouse liver sections (representative sections shown). Scale bars represent 100 μm.(B–E) Homeostatic levels of iron, heme, and endogenous p53 protein in the livers of Hfe−/− and Hfe+/+ mice (B and C) or Hfe+/+ mice fed on a normal or high-iron diet were measured (D and E). Iron or heme content was determined using an unsaturated iron-binding capacity or TMB assay, respectively (B and D), and protein levels were measured by immunoblotting (IB) with the indicated antibodies (C and E). In (B) and (D), iron or heme levels in the livers of wild-type mice fed a normal diet were set to 100%. Protein levels were normalized by setting the static endogenous p53 levels in the livers of Hfe+/+ mice (C) and normal-diet mice (E) as 100%. Comparative quantification of band intensities was performed with ImageJ. Bar graphs are shown as mean ± SEM (n = 3). *p < 0.05.
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Figure 1: Tumor Suppressor p53 Protein Is Downregulated in Iron Excess(A) Perls’ Prussian Blue staining of Hfe+/+ and Hfe−/− mouse liver sections (representative sections shown). Scale bars represent 100 μm.(B–E) Homeostatic levels of iron, heme, and endogenous p53 protein in the livers of Hfe−/− and Hfe+/+ mice (B and C) or Hfe+/+ mice fed on a normal or high-iron diet were measured (D and E). Iron or heme content was determined using an unsaturated iron-binding capacity or TMB assay, respectively (B and D), and protein levels were measured by immunoblotting (IB) with the indicated antibodies (C and E). In (B) and (D), iron or heme levels in the livers of wild-type mice fed a normal diet were set to 100%. Protein levels were normalized by setting the static endogenous p53 levels in the livers of Hfe+/+ mice (C) and normal-diet mice (E) as 100%. Comparative quantification of band intensities was performed with ImageJ. Bar graphs are shown as mean ± SEM (n = 3). *p < 0.05.

Mentions: Mice with homozygous deletion of the human hemochromatosis (Hfe) gene (Hfe−/−) faithfully recapitulate most human HH symptoms, including significant liver iron overload as assessed by Perls’ Prussian Blue staining (Zhou et al., 1998) (Figure 1A). Using a 3,3′,5,5′-tetramethylbenzidine (TMB) assay to quantitatively assess liver heme content, we found that Hfe−/− mouse liver lysate had 9-fold more heme than lysate from wild-type livers (3.71 ± 0.4 nmol/mg protein versus 0.41 ± 0.12 nmol/mg protein) (Figure 1B). We next assessed liver p53 protein content and found that total Hfe−/− liver lysates had significantly lower endogenous p53 protein levels than wild-type livers (Figure 1C). The level of p53 protein in primary hepatocytes from Hfe−/− mice was also markedly lower than that in wild-type hepatocytes (Figure S1A). Moreover, compared to wild-type mice on a normal diet, wild-type mice fed with a high iron diet had considerably lower p53 protein levels (Figures 1D and 1E). Thus, iron overload in mice, due to either a genetic perturbation of iron metabolism or a high iron diet, correlates with a significant reduction in p53 protein levels.


Iron metabolism regulates p53 signaling through direct heme-p53 interaction and modulation of p53 localization, stability, and function.

Shen J, Sheng X, Chang Z, Wu Q, Wang S, Xuan Z, Li D, Wu Y, Shang Y, Kong X, Yu L, Li L, Ruan K, Hu H, Huang Y, Hui L, Xie D, Wang F, Hu R - Cell Rep (2014)

Tumor Suppressor p53 Protein Is Downregulated in Iron Excess(A) Perls’ Prussian Blue staining of Hfe+/+ and Hfe−/− mouse liver sections (representative sections shown). Scale bars represent 100 μm.(B–E) Homeostatic levels of iron, heme, and endogenous p53 protein in the livers of Hfe−/− and Hfe+/+ mice (B and C) or Hfe+/+ mice fed on a normal or high-iron diet were measured (D and E). Iron or heme content was determined using an unsaturated iron-binding capacity or TMB assay, respectively (B and D), and protein levels were measured by immunoblotting (IB) with the indicated antibodies (C and E). In (B) and (D), iron or heme levels in the livers of wild-type mice fed a normal diet were set to 100%. Protein levels were normalized by setting the static endogenous p53 levels in the livers of Hfe+/+ mice (C) and normal-diet mice (E) as 100%. Comparative quantification of band intensities was performed with ImageJ. Bar graphs are shown as mean ± SEM (n = 3). *p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4219651&req=5

Figure 1: Tumor Suppressor p53 Protein Is Downregulated in Iron Excess(A) Perls’ Prussian Blue staining of Hfe+/+ and Hfe−/− mouse liver sections (representative sections shown). Scale bars represent 100 μm.(B–E) Homeostatic levels of iron, heme, and endogenous p53 protein in the livers of Hfe−/− and Hfe+/+ mice (B and C) or Hfe+/+ mice fed on a normal or high-iron diet were measured (D and E). Iron or heme content was determined using an unsaturated iron-binding capacity or TMB assay, respectively (B and D), and protein levels were measured by immunoblotting (IB) with the indicated antibodies (C and E). In (B) and (D), iron or heme levels in the livers of wild-type mice fed a normal diet were set to 100%. Protein levels were normalized by setting the static endogenous p53 levels in the livers of Hfe+/+ mice (C) and normal-diet mice (E) as 100%. Comparative quantification of band intensities was performed with ImageJ. Bar graphs are shown as mean ± SEM (n = 3). *p < 0.05.
Mentions: Mice with homozygous deletion of the human hemochromatosis (Hfe) gene (Hfe−/−) faithfully recapitulate most human HH symptoms, including significant liver iron overload as assessed by Perls’ Prussian Blue staining (Zhou et al., 1998) (Figure 1A). Using a 3,3′,5,5′-tetramethylbenzidine (TMB) assay to quantitatively assess liver heme content, we found that Hfe−/− mouse liver lysate had 9-fold more heme than lysate from wild-type livers (3.71 ± 0.4 nmol/mg protein versus 0.41 ± 0.12 nmol/mg protein) (Figure 1B). We next assessed liver p53 protein content and found that total Hfe−/− liver lysates had significantly lower endogenous p53 protein levels than wild-type livers (Figure 1C). The level of p53 protein in primary hepatocytes from Hfe−/− mice was also markedly lower than that in wild-type hepatocytes (Figure S1A). Moreover, compared to wild-type mice on a normal diet, wild-type mice fed with a high iron diet had considerably lower p53 protein levels (Figures 1D and 1E). Thus, iron overload in mice, due to either a genetic perturbation of iron metabolism or a high iron diet, correlates with a significant reduction in p53 protein levels.

Bottom Line: Iron excess is closely associated with tumorigenesis in multiple types of human cancers, with underlying mechanisms yet unclear.Strikingly, the iron polyporphyrin heme binds to p53 protein, interferes with p53-DNA interactions, and triggers both nuclear export and cytosolic degradation of p53.Moreover, in a tumorigenicity assay, iron deprivation suppressed wild-type p53-dependent tumor growth, suggesting that upregulation of wild-type p53 signaling underlies the selective efficacy of iron deprivation.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Molecular Biology, Chinese Academy of Sciences, 320 Yue-yang Road, Shanghai 200031, China; University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yue-yang Road, Shanghai 200031, China.

Show MeSH
Related in: MedlinePlus