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. Author manuscript; available in PMC: 2009 May 4.
Published in final edited form as: Nat Cell Biol. 2008 May 4;10(6):676–687. doi: 10.1038/ncb1730

Figure 4.

Figure 4

p53 deletion attenuates ATP depletion during glucose deprivation and favours survival under metabolic stress. (a) Cytosolic ATP levels in WT and p53-/- HCT116 cells in the absence of glucose. Measurements were performed on luciferase-expressing HCT116, after perfusion of the cells with medium first containing then missing glucose. (b) Effect of methylpyruvate (MetPyr) on ATP levels in WT p53-/- HCT116 cells depleted of glucose. ATP levels were measured as in a, in the presence of glucose and 15 min after its withdrawal or replacement by MetPyr. (c) Effect of autophagy on the ATP levels of WT and p53-/- HCT116 cells depleted of glucose. Cells were transfected with siRNAs specific for Beclin 1 and AMPKα, or they were treated with rapamycin for 6 h, followed by measurement of ATP levels as in a, before or after glucose withdrawal (means ± s.d. of triplicates, 3 independent experiments). (d) Metabolic stress-induced cell death is attenuated in the absence of p53. HCT116 cells were transfected with control, Atg5-, Atg10-, or AMPKα-specific siRNAs and were subjected 48 h later to metabolic stress (cultured for 48 h in nutrient-free, hypoxic conditions) and stained with DiOC6(3) and PI. The black and white portions of the columns refer to the DiOC6(3)low PI- (dying) and DiOC6(3)low PI+(dead) population, respectively. (e) Metabolic stress-induced decrease of clonogenic survival was attenuated in the absence of p53. HCT116 cells subjected to metabolic stress as in d were monitored for clonogenic survival. (f) Expression of Beclin 1 in MCF7 cells restores the survival advantage conferred by p53 depletion. MCF7 cells that carry a tetracycline-repressible Beclin 1 expression construct were cultured to avoid Beclin 1 expression or to induce it, transfected with a control siRNA or a p53-specific siRNA, subjected to metabolic stress, and finally stained with DiOC6(3)/PI. (g) Effect of p53 and autophagy on the survival of metabolically stressed MEFs. WT MEFs were transfected with the indicated siRNAs and then subjected to metabolic stress before performing clonogenic assays. Results in d-g are mean ± s.d. of 3 separate experiments (*P < 0.05); Co, control.