Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To identify critical genes that mediate p53-induced growth arrest and apoptosis at a global level, we profiled a human lung carcinoma cell model in which cells undergo growth arrest and apoptosis in a p53 and DNA damage-dependent manner. Profiling of the Affymetrix human HG-U1333 GeneChip, covering the entire human transcriptome, revealed about 3, 000 unique genes either induced or repressed during p53-induced growth arrest or apoptosis, respectively. A total of 1, 057 genes, including many well-known p53 targets, responded to both conditions. A mini apoptotic protein database was generated from 3, 033 unique apoptosis responsive genes. Analysis of this database yielded 23 proteins with a pro-apoptotic BH3 domain and three with anti-apoptotic BIR2/BIR3 domains, including well-known p53 targets: Bax, Puma, Noxa and survivin. In addition, 14 mitochondrial proteins were identified that contain a pro-apoptotic AVPI-like motif, and 15 proteins were identified that contain a DAVPI-like domain with the potential of being cleaved by caspases during apoptosis to release the AVPI motif. Many of the genes we identified with these domains do contain p53-binding sites either in the promoter or in the first three introns, suggesting a high probability of being direct p53 targets. Pathway analysis revealed that p53 might control the Wnt pathway through transcriptional regulation of some of its components. Thus, global chip profiling coupled with bioinformatics analysis is a powerful tool in identification of genes critical for p53-induced apoptosis. Further characterization of these genes will lead to a better understanding of the mechanism of p53 action and p53 regulation of other signaling pathways. It will also provide novel cancer drug targets for further validation.
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PMID:Global genechip profiling to identify genes responsive to p53-induced growth arrest and apoptosis in human lung carcinoma cells. 1450 18

Alterations in MYC and p53 are hallmarks of cancer. p53 coordinates the response to gamma irradiation (gamma-IR) by either triggering apoptosis or cell cycle arrest. c-Myc activates the p53 apoptotic checkpoint, and thus tumors overexpressing MYC often harbor p53 mutations. Nonetheless, many of these cancers are responsive to therapy, suggesting that Myc may sensitize cells to gamma-IR independent of p53. In mouse embryo fibroblasts (MEFs) and in E micro -myc transgenic B cells in vivo, c-Myc acts in synergy with gamma-IR to trigger apoptosis, but alone, when cultured in growth medium, it does not induce a DNA damage response. Surprisingly, c-Myc also sensitizes p53-deficient MEFs to gamma-IR-induced apoptosis. In normal cells, and in precancerous B cells of E micro -myc transgenic mice, this apoptotic response is associated with the suppression of the antiapoptotic regulators Bcl-2 and Bcl-X(L) and with the concomitant induction of Puma, a proapoptotic BH3-only protein. However, in p53-null MEFs only Bcl-X(L) expression was suppressed, suggesting levels of Bcl-X(L) regulate the response to gamma-IR. Indeed, Bcl-X(L) overexpression blocked this apoptotic response, whereas bcl-X-deficient MEFs were inherently and selectively sensitive to gamma-IR-induced apoptosis. Therefore, MYC may sensitize tumor cells to DNA damage by suppressing Bcl-X.
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PMID:c-Myc augments gamma irradiation-induced apoptosis by suppressing Bcl-XL. 1451 95

The adenovirus E4orf6 is a viral oncoprotein known to cooperate with the E1A gene product in transforming primary murine cells. It has been shown to inhibit the apoptotic activities of p53 and p73 through direct binding to these proteins. Here, we demonstrate that the adenovirus E4orf6 protein inhibits apoptosis mediated by BNIP3 and Bik, which are BH3-only proteins of the Bcl-2 family. This activity was not mediated by p53 and p73 because E4orf6 had the same effect on the apoptosis in Saos-2 cells that do not express p53-related genes. It was also ascertained that E4orf6 could change the mitochondrial localization of BNIP3 and Bik. A mutant lacking the nuclear export signal of E4orf6 failed to inhibit apoptosis and to translocate BNIP3 protein from the mitochondria. Moreover, it was also established that E4orf6 was able to interact with BNIP3 and Bik. In BNIP3 protein, the region required for the interaction included the transmembrane domain, which is required for the localization of BNIP3 to the mitochondria. These results suggest that E4orf6 is exported from the nucleus to the cytoplasm, enabling it to interact with BH3-only proteins, eventually leading to the inhibition of apoptotic activity.
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PMID:Nuclear export of adenovirus E4orf6 protein is necessary for its ability to antagonize apoptotic activity of BH3-only proteins. 1453 39

The BH3-only protein, PUMA, plays an important role in p53-mediated apoptosis. The apoptotic effect of PUMA on the mitochondria was studied using a p53-negative, human leukemia K562 cell line. Overexpression of PUMA was accompanied by an increased Bax expression, Bax conformational change, and translocation to mitochondria. A PUMA-BH3 peptide can induce Bax conformational change, cytochrome c release, and reduction in the mitochondrial membrane potential (DeltaPsi(m)) in isolated K562 mitochondria and can be inhibited by Bcl-XL. The homo-dimer of Bax/Bax was also weakly shown after mitochondria were treated with PUMA-BH3 peptide but may not be lethal for PUMA-induced apoptosis in K562 cells. Our results suggest that PUMA-induced Bax conformational change and Bax translocation to mitochondria can be separate events and the conformational change in Bax is crucial for PUMA-induced mitochondrial dysfunction.
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PMID:Bax conformational change is a crucial step for PUMA-mediated apoptosis in human leukemia. 1455 Feb 97

More than a decade ago, it was found that one of the two essential physiological functions of p53 is to selectively destroy stressed cells through apoptosis. Despite the large number of studies describing p53-dependent apoptosis since then, how p53 turns on the apoptotic switch has remained enigmatic. In this issue of Cancer Cell, Jeffers et al. report that knockout of PUMA, a recently identified BH3-only Bcl-2 family protein, recapitulates virtually all apoptotic deficiency in p53 knockout mice. Their results indicate that PUMA is an essential mediator of p53-dependent and -independent apoptosis in vivo.
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PMID:No PUMA, no death: implications for p53-dependent apoptosis. 1458 51

Puma encodes a BH3-only protein that is induced by the p53 tumor suppressor and other apoptotic stimuli. To assess its physiological role in apoptosis, we generated Puma knockout mice by gene targeting. Here we report that Puma is essential for hematopoietic cell death triggered by ionizing radiation (IR), deregulated c-Myc expression, and cytokine withdrawal. Puma is also required for IR-induced death throughout the developing nervous system and accounts for nearly all of the apoptotic activity attributed to p53 under these conditions. These findings establish Puma as a principal mediator of cell death in response to diverse apoptotic signals, implicating Puma as a likely tumor suppressor.
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PMID:Puma is an essential mediator of p53-dependent and -independent apoptotic pathways. 1458 59

Apoptotic programmed cell death pathways are activated by a diverse array of cell extrinsic and intrinsic signals, most of which are ultimately coupled to the activation of effector caspases. In many instances, this involves an obligate propagation through mitochondria, causing egress of critical proapoptotic regulators to the cytosol. Central to the regulation of the mitochondrial checkpoint is a complex three-way interplay between members of the BCL-2 family, which are comprised of an antiapoptotic subgroup including BCL-2 itself, and the proapoptotic BAX,BAK and BH3-domain-only subgroups. Constituents of all three of these BCL-2 classes, however, also converge on the endoplasmic reticulum (ER), an organelle whose critical contributions to apoptosis is only now becoming apparent. In addition to propagating death-inducing stress signals itself, the ER also contributes in a fundamental way to Fas-mediated apoptosis and to p53-dependent pathways resulting from DNA damage and oncogene expression. Mobilization of ER calcium stores can initiate the activation of cytoplasmic death pathways as well as sensitize mitochondria to direct proapoptotic stimuli. Additionally, the existence of BCL-2-regulated initiator procaspase activation complexes at the ER membrane has also been described. Here, we review the potential underlying mechanisms involved in these events and discuss pathways for ER-mitochondrial crosstalk pertinent to a number of cell death stimuli.
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PMID:Regulation of apoptosis by endoplasmic reticulum pathways. 1463 22

Hypoxia is a common cause of cell death and is implicated in many disease processes including stroke and chronic degenerative disorders. In response to hypoxia, cells express a variety of genes, which allow adaptation to altered metabolic demands, decreased oxygen demands, and the removal of irreversibly damaged cells. Using polymerase chain reaction-based suppression subtractive hybridization to find genes that are differentially expressed in hypoxia, we identified the BH3-only Bcl-2 family protein Noxa. Noxa is a candidate molecule mediating p53-induced apoptosis. We show that Noxa promoter responds directly to hypoxia via hypoxia-inducible factor (HIF)-1alpha. Suppression of Noxa expression by antisense oligonucleotides rescued cells from hypoxia-induced cell death and decreased infarction volumes in an animal model of ischemia. Further, we show that reactive oxygen species and resultant cytochrome c release participate in Noxa-mediated hypoxic cell death. Altogether, our results show that Noxa is induced by HIF-1alpha and mediates hypoxic cell death.
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PMID:BH3-only protein Noxa is a mediator of hypoxic cell death induced by hypoxia-inducible factor 1alpha. 1469 81

The induction of apoptosis is a fundamental mechanism by which the p53 transcriptional activator protein suppresses tumor development. Recently, the roles of several p53 target genes in mediating the p53 apoptotic response have been queried through loss-of-function analysis with knockout mouse models. These studies have demonstrated that the p53 targets Noxa, Puma, and Perp play cell type-specific roles in p53-mediated apoptosis. Perp, a tetraspan protein localizing to the plasma membrane, rather than to mitochondria, is a novel type of p53 effector that may stimulate apoptosis through a different mechanism from the BH3-containing proteins Noxa, Puma, and Bax.
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PMID:Perp-etrating p53-dependent apoptosis. 1472 58

The p53 tumor suppressor protein is critically involved in cell cycle regulation and programmed cell death. Here we show that expression of the BH3-only protein ITM2Bs is able to induce apoptotic cell death in p53+/+, as well as in p53-/- cell lines. This cell death involves neither subcellular redistribution of p53 nor transcriptional regulation of p53 target genes such as Bax, Ras, Puma or Bcl-2. Together, our data provide evidence for a p53-independent apoptotic role of ITM2Bs.
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PMID:Induction of p53-independent apoptosis by the BH3-only protein ITM2Bs. 1474 82


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