Vanadate protects human neuroblastoma SH-SY5Y cells against peroxynitrite-induced cell death

We investigated the effect of vanadate, a tyrosine phosphatase inhibitor, on cell death induced by peroxynitrite in human neuroblastoma SH-SY5Y cells. Vanadate prevented cell death induced by 3-morpholinosydnonimine (SIN-1), a peroxynitrite donor; whereas SIN-1-induced cell death was not prevented by neither okadaic acid, an inhibitor of serine/threonine phosphatases 1 and 2A, nor cyclosporin A, an inhibitor of serine/threonine phosphatase 2B. Vanadate did not prevent cell death induced by N-ethyl-2-(1-ethyl-hydroxy-2-nitrosohydrazino)-ethanamine, a nitric oxide donor. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3-kinase), did not block the protective effect of vanadate, suggesting that the protective effect of vanadate is independent on PI3-kinase. Vanadate increased tyrosine phosphorylation of several proteins including the focal adhesion protein p130 Crk-associated substrate (p130(cas)). By the treatment with SIN-1, the endogenous association of p130(cas) and Crk was disrupted, and the association was restored by vanadate treatment. These results suggest that disruption of tyrosine phosphorylation signaling may be critical for peroxynitrite-induced cell death, and that vanadate prevents cell death at least in part through the enhancement in tyrosine phosphorylation of the proteins including p130(cas).     

Subcellular distribution of human tyrosine hydroxylase isoforms 1 and 4 in SH-SY5Y cells

Tyrosine hydroxylase (TH) is the key enzyme that controls the rate of synthesis of the catecholamines. SH-SY5Y cells with stable transfections of either human tyrosine hydroxylase isoform 1 (hTH1) or human tyrosine hydroxylase isoform 4 (hTH4) were used to determined the subcellular distribution of TH protein and phosphorylated TH, under basal conditions and after muscarine stimulation. Muscarine was previously shown to increase the phosphorylation of only serine 19 and serine 40 in hTH1 cells. Under basal conditions, the hTH1 and hTH4 proteins, their serine 19 phosphorylated forms and hTH1 phosphorylated at serine 40 were all similarly distributed; with ~80% in the cytosolic fraction, ~20% in the membrane fraction, and less than 1%, or not detectable, in the nuclear fraction. However, hTH4 phosphorylated at serine 71 had a significantly different distribution with ~65% cytosolic and ~35% membrane associated. Muscarine stimulation led to hTH1 being redistributed from the cytosol and nuclear fractions to the membrane fraction and hTH4 being redistributed from the cytosol to the nuclear fraction. These muscarine stimulated redistributions were not due to TH phosphorylation at serine 19, serine 40, or serine 71 and were most likely due to TH binding to proteins whose phosphorylation was increased by muscarine. This is the first study to show a difference in subcellular distribution between two human TH isoforms under basal and stimulated conditions.     

Bcl-x L blocks mitochondrial multiple conductance channel activation and inhibits 6-OHDA-induced death in SH-SY5Y cells

Apoptosis is an active process that is regulated by different signalling pathways. One of the more important organelles involved in apoptosis regulation is the mitochondrion. Electron chain transport disruption increases free radical production leading to multiple conductance channel opening, release of cytochrome c and caspase activation. This death pathway can be blocked by anti-apoptotic members of the Bcl-2 protein family that might shift redox potential to a more reduced state, preventing free radical-mediated damage. 6-Hydroxydopamine (6-OHDA) has been widely used to generate Parkinson's disease-like models. It is able to generate free radicals and to induce catecholaminergic cell death. In this paper we have used the human neuroblastoma cell line SH-SY5Y overexpressing Bcl-x(L) as a model to gain insights into the mechanisms through which Bcl-x(L) blocks 6-OHDA-induced cell death and to identify the molecular targets for this action. Herein, we present evidence supporting that the Bcl-x(L)-anti-apoptotic signal pathway seems to prevent mitochondrial multiple conductance channel opening, cytochrome c release and caspase-3 like activity following 6-OHDA treatment in the human neuroblastoma cell line SH-SY5Y.     

Apomorphine attenuates 6-hydroxydopamine-induced apoptotic cell death in SH-SY5Y cells

Abstract

Enhanced oxidative stress is implicated in the pathogenesis of Parkinson's disease. The catecholaminergic neurotoxin 6-hydroxydopamine (6-OHDA) induces the production of reactive oxygen species (ROS), leading to neuronal cell death. On the other hand, apomorphine, a dopamine D1/D2 receptor agonist and known as a potent antioxidant, has been reported to have a neuroprotective effect. In the present study, we investigated the effect of apomorphine on 6-OHDA-induced apoptotic cell death using the human dopaminergic neuroblastoma cell line, SH-SY5Y. The co-treatment of cells with apomorphine significantly attenuated 6-OHDA-induced ROS generation, the phosphorylation of c-Jun N-terminal kinase (JNK), DNA fragmentation and subsequent apoptotic cell death. In addition, pretreatment with apomorphine for 24 h and the following concomitant treatment enhanced the protective effects against 6-OHDA-induced toxicity except for the attenuation of JNK phosphorylation. We also demonstrated that pretreatment alone with apomorphine for 24 h prior to the exposure confers resistance against 6-OHDA-induced cell toxicity. These findings suggested that apomorphine acts principally as a radical scavenger to suppress the level of ROS and ROS-stimulated apoptotic signaling pathway, whereas the other mechanisms might be involved in the protective effects.     

Apomorphine attenuates 6-hydroxydopamine-induced apoptotic cell death in SH-SY5Y cells

Enhanced oxidative stress is implicated in the pathogenesis of Parkinson's disease. The catecholaminergic neurotoxin 6-hydroxydopamine (6-OHDA) induces the production of reactive oxygen species (ROS), leading to neuronal cell death. On the other hand, apomorphine, a dopamine D1/D2 receptor agonist and known as a potent antioxidant, has been reported to have a neuroprotective effect. In the present study, we investigated the effect of apomorphine on 6-OHDA-induced apoptotic cell death using the human dopaminergic neuroblastoma cell line, SH-SY5Y. The co-treatment of cells with apomorphine significantly attenuated 6-OHDA-induced ROS generation, the phosphorylation of c-Jun N-terminal kinase (JNK), DNA fragmentation and subsequent apoptotic cell death. In addition, pretreatment with apomorphine for 24 h and the following concomitant treatment enhanced the protective effects against 6-OHDA-induced toxicity except for the attenuation of JNK phosphorylation. We also demonstrated that pretreatment alone with apomorphine for 24 h prior to the exposure confers resistance against 6-OHDA-induced cell toxicity. These findings suggested that apomorphine acts principally as a radical scavenger to suppress the level of ROS and ROS-stimulated apoptotic signaling pathway, whereas the other mechanisms might be involved in the protective effects.     

Rosiglitazone protects human neuroblastoma SH-SY5Y cells against acetaldehyde-induced cytotoxicity

Acetaldehyde, an inhibitor of mitochondrial function, has been widely used as a neurotoxin because it elicits a severe Parkinson's disease-like syndrome with elevation of the intracellular reactive oxygen species level and apoptosis. Rosiglitazone, a peroxisome proliferator-activated receptor-gamma agonist, has been known to show various non-hypoglycemic effects, including anti-inflammatory, anti-atherogenic, and anti-apoptotic. In this study, we investigated the protective effects of rosiglitazone on acetaldehyde-induced apoptosis in human neuroblastoma SH-SY5Y cells and attempted to examine its mechanism. Acetaldehyde-induced apoptosis was moderately reversed by rosiglitazone treatment. Our results suggest that the protective effects of rosiglitazone on acetaldehyde-induced apoptosis may be ascribed to ability to induce the expression of anti-oxidant enzymes and to regulate Bcl-2 and Bax expression. These data indicate that rosiglitazone may provide a useful therapeutic strategy for the prevention of progressive neurodegenerative disease such as Parkinson's disease.     

Retinoic acid protects against proteasome inhibition associated cell death in SH-SY5Y cells via the AKT pathway

Inhibition of proteasome activity and the resulting protein accumulation are now known to be important events in the development of many neurological disorders, including Alzheimer’s and Parkinson’s diseases. Abnormal or over expressed proteins cause endoplasmic reticulum and oxidative stress leading to cell death, thus, normal proteasome function is critical for their removal. We have shown previously, with cultured SH-SY5Y neuroblastoma cells, that proteasome inhibition by the drug epoxomicin results in accumulation of ubiquitinated proteins. This causes obligatory loading of the mitochondria with calcium (Ca²⁺), resulting in mitochondrial damage and cytochrome c release, followed by programmed cell death (PCD). In the present study, we demonstrate that all-trans-retinoic acid (RA) pretreatment of SH-SY5Y cells protects them from PCD death after subsequent epoxomicin treatment which causes proteasome inhibition. Even though ubiquitinated protein aggregates are present, there is no evidence to suggest that autophagy is involved. We conclude that protection by RA is likely by mechanisms that interfere with cell stress-PCD pathway that otherwise would result from protein accumulation after proteasome inhibition. In addition, although RA activates both the AKT and ERK phosphorylation signaling pathways, only pretreatment with LY294002, an inhibitor of PI3-kinase in the AKT pathway, removed the protective effect of RA from the cells. This finding implies that RA activation of the AKT signaling cascade takes precedence over its activation of ERK1/2 phosphorylation, and that this selective effect of RA is key to its protection of epoxomicin-treated cells. Taken together, these findings suggest that RA treatment of cultured neuroblastoma cells sets up conditions under which proteasome inhibition, and the resultant accumulation of ubiquitinated proteins, loses its ability to kill the cells and may likely play a therapeutic role in neurodegenerative diseases.     

GRP94 reduces cell death in SH-SY5Y cells perturbated calcium homeostasis

The endoplasmic reticulum (ER) resident-94 kDa glucose-regulated protein (GRP94), plays a pivotal role in cell death due to ER stress. In our study expression of GRP94 was increased in human neuroblastoma SH-SY5Y cells due to exposure to calcium ionophore A23187. A23187-mediated cell death was associated with activation of the major cysteine proteases, caspase-3 and calpain. Pretreatment with adenovirus-mediated antisense GRP94 (AdGRP94AS) reduced viability of SH-SY5Y cells subjected to A23187 treatment compared with wild type cells or cells with adenovirus-mediated overexpression of GRP94 (AdGRP94S). These results indicated that suppression of GRP94 is associated with accelerated cell death. Moreover, expression of GRP94 suppressed A23187-induced cell death and stabilized calcium homeostasis.     

Mitochondrial-targeted active Akt protects SH-SY5Y neuroblastoma cells from staurosporine-induced apoptotic cell death

Akt is a serine/threonine protein kinase that plays a vital role in promoting cellular survival. Predominantly cytosolic, upon stimulation with growth-factors or stress, active Akt translocates into mitochondria, but the functions of Akt in mitochondria are not yet fully understood. Mitochondria play a central role in apoptotic pathways and given Akt's functions in the cytoplasm, Akt in mitochondria may help preserve mitochondrial integrity during cellular stress. To test if the translocation of Akt into mitochondria is neuroprotective, adenoviral vectors expressing a constitutively active Akt, Ad-HA-Akt (DD), and a constitutively active Akt with a mitochondrial targeting signal, Ad-Mito-HA-Akt (DD), were generated. Human SH-SY5Y neuroblastoma cells expressing the adenoviral constructs were treated with staurosporine to initiate intrinsic apoptotic cell death and several aspects of the mitochondrial apoptotic pathway were evaluated. Expression of active Akt targeted to mitochondria was found to be sufficient to significantly reduce staurosporine-induced activation of caspase-3 and caspase-9, the release of cytochrome c from mitochondria, and Bax oligomerization at mitochondria. These findings demonstrate that intramitochondrial active Akt results in efficient protection against apoptotic signaling.     

Adiponectin protects human neuroblastoma SH-SY5Y cells against MPP+-induced cytotoxicity

1-Methyl-4-phenylpyridinium ion (MPP+), an inhibitor of mitochondrial complex I, has been widely used as a neurotoxin because it elicits a severe Parkinson's disease-like syndrome characterized by elevation of intracellular reactive oxygen species level and apoptotic death. Adiponectin, secreted from adipose tissue, mediates systemic insulin sensitivity with liver and muscle as target organs. Adiponectin can also suppress superoxide generation in endothelial cells. In the present study, we investigated the protective effects of adiponectin on MPP+-induced cytotoxicity in human neuroblastoma SH-SY5Y cells, as well as the underlying mechanism. Our results suggest that the protective effects of adiponectin on MPP+-induced apoptosis may be ascribed to its anti-oxidative properties, anti-apoptotic activity via inducing expression of SOD and catalase, and regulation of Bcl-2 and Bax expression. These data indicated that adiponectin might provide a useful therapeutic strategy for the treatment of progressive neurodegenerative diseases such as Parkinson's disease.     

Protective effect of isoflavones against homocysteine-mediated neuronal degeneration in SH-SY5Y cells

Previously, we reported that isoflavones exert a protective effect against the endoplasmic reticulum (ER) stress-mediated neuronal degeneration, and ER stress-mediated homocysteine toxicity may play an important role in the pathogenesis of neurodegeneration. Therefore, in this study we investigated the effects of isoflavones (genistein and daidzein) against homocysteine-mediated neurotoxicity in SH-SY5Y human neuroblastoma cells. The treatment of cells with either 17β-estradiol or isoflavones significantly protected the cells against homocysteine-mediated apoptosis. Isoflavones repressed homocysteine-mediated ER stress, reflected in the reduced expression of the immunoglobin heavy chain-binding protein mRNA, spliced X-box-protein-1 mRNA and the phosphorylated form of eukaryotic translation initiation factor 2α protein. Homocysteine caused significant increases in intracellular S-adenosylhomocysteine (SAH) and DNA damage. Isoflavones significantly alleviated DNA damage, but did not change SAH levels. Furthermore, the treatment of cells with isoflavones significantly reduced the microtubule-associated protein tau hyperphosphorylation by inactivating glycogen synthase kinase-3β and activating serine/threonine-protein phosphatase 2A. These results clearly demonstrate that isoflavones alleviate the ER stress- and DNA damage-mediated neurodegeneration caused by homocysteine.     

Hydrogen sulfide protects SH-SY5Y cells against 6-hydroxydopamine-induced endoplasmic reticulum stress

Endoplasmic reticulum (ER) stress has been implicated in several neurodegenerative diseases, including Parkinson's disease. The present study attempted to investigate the effect of hydrogen sulfide (H(2)S) on 6-hydroxydopamine (6-OHDA)-induced ER stress in SH-SY5Y cells. We found in the present study that exogenous application of sodium hydrosulfide (NaHS; an H(2)S donor, 100 μM) significantly attenuated 6-OHDA (50 μM)-induced cell death. NaHS also reversed the upregulation of cleaved poly(ADP-ribose) polymerase and caspase 9 in 6-OHDA-treated cells. Consistent with its cytoprotective effects, NaHS markedly reduced 6-OHDA induced-ER stress responses, including the upregulated levels of eukaryotic initiation factor-2α phosphorylation, glucose-regulated protein 78, and C/EBP homologous protein expression. The protective effect of H(2)S on ER stress was attenuated by blockade of Akt activity with an Akt inhibitor or inhibition of heat shock protein (Hsp)90 with geldanamycin but not by suppression of ERK1/2 with PD-98059. Blockade of Akt also significantly decreased the protein abundance of Hsp90 in SH-SY5Y cells. Moreover, overexpression of cystathionine β-synthase (a main H(2)S-synthesizing enzyme in the brain) elevated the Hsp90 protein level and suppressed 6-OHDA-induced ER stress. In conclusion, the protective effect of H(2)S against 6-OHDA-induced ER stress injury in SH-SY5Y cells involves the Akt-Hsp90 pathway.     

Differential expression and signaling of the human histamine H3 receptor isoforms of 445 and 365 amino acids expressed in human neuroblastoma SH-SY5Y cells

In stably-transfected human neuroblastoma SH-SY5Y cells, we have compared the effect of activating two isoforms of 445 and 365 amino acids of the human histamine H₃ receptor (hH₃R₄₄₅ and hH₃R₃₆₅) on [³⁵S]-GTPγS binding, forskolin-induced cAMP formation, depolarization-induced increase in the intracellular concentration of Ca²⁺ ions ([Ca²⁺]i) and depolarization-evoked [^3?H]-dopamine release. Maximal specific binding (B_max) of [^3?H]-N-methyl-histamine to cell membranes was 953?±?204 and 555?±?140?fmol/mg protein for SH-SY5Y-hH₃R₄₄₅ and SH-SY5Y-hH₃R₃₆₅ cells, respectively, with similar dissociation constants (K_d, 0.86?nM and 0.81?nM). The mRNA of the hH₃R₃₆₅ isoform was 40.9?±?7.9% of the hH₃R₄₄₅ isoform. No differences in receptor affinity were found for the H₃R ligands histamine, immepip, (R)(-)-α-methylhistamine (RAMH), A-331440, clobenpropit and ciproxifan. Both the stimulation of [³⁵S]-GTPγS binding and the inhibition of forskolin-stimulated cAMP accumulation by the agonist RAMH were significantly larger in SH-SY5Y-hH₃R₄₄₅ cells ([³⁵S]-GTPγS binding, 158.1?±?7.5% versus 136.5?±?3.6% for SH-SY5Y-hH₃R₃₆₅ cells; cAMP accumulation, ?74.0?±?4.9% versus ?43.5?±?5.3%), with no significant effect on agonist potency. In contrast, there were no differences in the efficacy and potency of RAMH to inhibit [^3?H]-dopamine release evoked by 100?mM K⁺ (?18.9?±?3.0% and ?20.5?±?3.3%, for SH-SY5Y-hH₃R₄₄₅ and SH-SY5Y-hH₃R₃₆₅ cells), or the inhibition of depolarization-induced increase in [Ca²⁺]i (S2/S1 ratios: parental cells 0.967?±?0.069, SH-SY5Y-hH₃R₄₄₅ cells 0.639?±?0.049, SH-SY5Y-hH₃R₃₆₅ cells 0.737?±?0.045). These results indicate that in SH-SY5Y cells, hH₃R₄₄₅ and hH₃R₃₆₅ isoforms regulate in a differential manner the signaling pathways triggered by receptor activation.     

20(R)-Ginsenoside Rg3 protects SH-SY5Y cells against apoptosis induced by oxygen and glucose deprivation/reperfusion

As shown in our previous studies, 20(R)-ginsenoside Rg3 [20(R)-Rg3] exerts a neuroprotective effect on a rat model of transient focal cerebral ischemia, and the mechanism through which it decreases the mRNA expression of calpain I and caspase-3 has been delineated. However, researchers do not know whether 20(R)-Rg3 exhibits a neuroprotective effect following oxygen-glucose deprivation and reperfusion (OGD/R) injury in vitro. In the present study, 20(R)-Rg3 increased cell viability, decreased the LDH leakage rate, and inhibited the apoptosis rate in a concentration-dependent manner. In addition, 20(R)-Rg3 markedly decreased cleaved caspase-3 protein expression. Furthermore, 20(R)-Rg3 significantly decreased the Bax mRNA and protein levels and increased the levels of Bcl-2 mRNA and protein, subsequently decreasing the Bax/Bcl-2 protein ratio. Based on these findings, 20(R)-Rg3 exerts a neuroprotective effect against OGD/R-induced apoptosis.     

Dosage effects of EGb761 on hydrogen peroxide-induced cell death in SH-SY5Y cells

Standardized extract from the leaves of the Ginkgo biloba tree, labeled EGb761, is one of the most popular herbal supplements, taken for its multivalent properties. In this study, dosage effects of EGb761 on hydrogen peroxide (H₂O₂)-induced apoptosis of human neuroblastoma SH-SY5Y cells were investigated. It was found that H₂O₂-induced apoptotic cell death in SH-SY5Y cells, which was revealed in DNA fragmentation, mitochondrial membrane potential depolarization, and activation of Akt, c-Jun N-terminal kinases (JNK) and caspase 3. Low doses of EGb761 (50–100 μg/ml) inhibited H₂O₂-induced cell apoptosis via inactivation of Akt, JNK and caspase 3 while high doses of EGb761 (250–500 μg/ml) enhanced H₂O₂ toxicities via inactivation of Akt and enhancement of activation of JNK and caspase 3. Additional experiments revealed that H₂O₂ decreased intracellular GSH content, which was also inhibited by low concentrations of EGb761 but enhanced after high concentrations of EGb761 treatment. This further suggests to us that dosage effects of EGb761 on apoptotic signaling proteins may be correlated with regulation of cell redox state. Therefore, treatment dosage may be one of the vital factors that determine the specific action of EGb761 on oxidative stress-induced cell apoptosis. To understand the mechanisms of dosage effects of EGb761 may have important clinical implications.     

Interaction between acylphosphatase and SERCA in SH-SY5Y cells

Ca²⁺ transport by sarco/endoplasmic reticulum, tightly coupled with the enzymatic activity of Ca²⁺-dependent ATPase, controls the cell cycle through the regulation of genes operating in the critical G₁ to S checkpoint. Experimental studies demonstrated that acylphosphatase actively hydrolyses the phosphorylated intermediate of sarco/endoplasmic reticulum calcium ATPase (SERCA) and therefore enhances the activity of Ca²⁺ pump. In this study we found that SH-SY5Y neuroblastoma cell division was blocked by entry into a quiescent G₀-like state by thapsigargin, a high specific SERCA inhibitor, highlighting the regulatory role of SERCA in cell cycle progression. Addition of physiological amounts of acylphosphatase to SY5Y membranes resulted in a significant increase in the rate of ATP hydrolysis of SERCA. In synchronized cells a concomitant variation of the level of acylphosphatase isoenzymes opposite to that of intracellular free calcium during the G₁ and S phases occurs. Particularly, during G₁ phase progression the isoenzymes content declined steadily and hit the lowest level after 6 h from G₀ to G₁ transition with a concomitant significant increase of calcium levels. No changes in free calcium and acylphosphatase levels upon thapsigargin inhibition were observed. Moreover, a specific binding between acylphosphatase and SERCA was demonstrated. No significant change in SERCA-2 expression was found. These findings suggest that the hydrolytic activity of acylphosphatase increase the turnover of the phosphoenzyme intermediate with the consequences of an enhanced efficiency of calcium transport across endoplasmic reticulum and a subsequent decrease in cytoplasmic calcium levels. A hypothesis about the modulation of SERCA activity by acylphosphatase during cell cycle in SY5Y cells in discussed.     

The role of insulin against hydrogen peroxide-induced oxidative damages in differentiated SH-SY5Y cells

Abstract

Exogenous hydrogen peroxide (H₂O₂) can easily penetrate into biological membranes and enhance the formation of other reactive oxygen species (ROS). In the present study, we have investigated the neuroprotective effects of insulin on H₂O₂-induced toxicity of retinoic acid (RA)-differentiated SH-SY5Y cells. To measure the changes in the cell viability of SH-SY5Y cells at different concentrations of H₂O₂ for 24?h, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT)-based assay was used and a 100?µM H₂O₂ was selected to establish a model of H₂O₂-induced oxidative stress. Further assays showed that 24?h of 100?µM H₂O₂-induced significant changes in the levels of lactate dehydrogenase (LDH), nitric oxide (NO), ROS, and calcium ion (Ca²⁺) in neuronal cells, but insulin can effectively diminish the H₂O₂-induced oxidative damages to these cells. Moreover, cells treated with insulin increased H₂O₂-induced suppression of glutathione levels and exerted an apparent suppressive effect on oxidative products. The results of insulin treatment with SH-SY5Y cells increased the Bcl-2 levels and decreased the Akt levels. The treatment of insulin had played a protective effect on H₂O₂-induced oxidative stress related to the Akt/Bcl-2 pathways.     

p53 directly suppresses BNIP3 expression to protect against hypoxia-induced cell death

Hypoxia stabilizes the tumour suppressor p53, allowing it to function primarily as a transrepressor; however, the function of p53 during hypoxia remains unclear. In this study, we showed that p53 suppressed BNIP3 expression by directly binding to the p53-response element motif and recruiting corepressor mSin3a to the BNIP3 promoter. The DNA-binding site of p53 must remain intact for the protein to suppress the BNIP3 promoter. In addition, taking advantage of zebrafish as an in vivo model, we confirmed that zebrafish nip3a, a homologous gene of mammalian BNIP3, was indeed induced by hypoxia and p53 mutation/knockdown enhanced nip3a expression under hypoxia resulted in cell death enhancement in p53 mutant embryos. Furthermore, p53 protected against hypoxia-induced cell death mediated by p53 suppression of BNIP3 as illustrated by p53 knockdown/loss assays in both human cell lines and zebrafish model, which is in contrast to the traditional pro-apoptotic role of p53. Our results suggest a novel function of p53 in hypoxia-induced cell death, leading to the development of new treatments for ischaemic heart disease and cerebral stroke.