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

Endoplasmic reticulum (ER) stress has been implicated in the pathogenesis of ischemic and neurodegenerative disorders. Treatment of human SH-SY5Y neuroblastoma cells with tunicamycin, an inhibitor of protein glycosylation, rapidly induced the expression of target genes of the unfolded protein response. However, prolonged treatment also triggered a delayed, caspase-dependent cell death. Microarray analysis of gene expression changes during tunicamycin-induced apoptosis revealed that the Bcl-2 homology domain 3-only family member, Bcl-2 binding component 3/p53 upregulated modulator of apoptosis (Bbc3/PUMA), was the most strongly induced pro-apoptotic gene. Expression of Bbc3/PUMA correlated with a Bcl-xL-sensitive release of cytochrome c and the activation of caspase-9 and -3. Increased expression of Bbc3/PUMA was also observed in p53-deficient human cells, in response to the ER stressor thapsigargin, and in rat hippocampal neurons after transient forebrain ischemia. Overexpression of Bbc3/PUMA was sufficient to trigger apoptosis in SH-SY5Y neuroblastoma cells, and human cells deficient in Bbc3/PUMA showed dramatically reduced apoptosis in response to ER stress. Our data suggest that the transcriptional induction of Bbc3/PUMA may be sufficient and necessary for ER stress-induced apoptosis.
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PMID:Gene expression during ER stress-induced apoptosis in neurons: induction of the BH3-only protein Bbc3/PUMA and activation of the mitochondrial apoptosis pathway. 1291 14

Genetic alterations of p53, which monitors DNA damage and operates cellular checkpoints, is a major factor in the development of many types of cancer in human. PUMA, a direct mediator of p53-associated apoptosis, was recently identified. The PUMA gene was mapped to chromosomal arm 19q, a region frequently deleted in head/neck and lung cancers. We analyzed 30 primary tumors (15 head/neck and 15 lung) for loss of heterozygosity (LOH) at 19q using seven widely spaced microsatellite markers. LOH in at least one marker was present in 8 (56%) of the head/neck and 4 (26.6%) of the lung cancer samples. Overall, D19S408 and D19S412, showed the highest rates of allelic loss (23.3 and 16.6%, respectively). We then sequenced the entire coding region of the PUMA gene in all the 30 primary tumors and in 10 head/neck cancer cell lines. No mutations of PUMA were detected in any samples examined, regardless of the mutational status of the p53 gene. Forced expression of wild-type PUMA in JHU-012 and JHU-013 head/neck cancer cell lines significantly inhibited colony formation. Although PUMA suppresses tumor cell growth in head/neck cancer, it does not appear to be a direct target of inactivation in head and neck tumorigenesis.
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PMID:PUMA in head and neck cancer. 1296 26

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

Exposure of normal mouse fibroblasts (MEF3T3) to ionizing radiation (IR) resulted in a dose-dependent increase of mTOR mRNA and protein levels and the shuttling of the mTOR protein from its normal, predominantly mitochondrial location to the cell nucleus. The same IR doses that activated mTOR induced the phosphorylation of p53 on Ser(18) (mouse equivalent to human Ser(15)) and the subsequent transcriptional activation of PUMA, a known proapoptotic p53-target gene, and promoted apoptosis involving increased overall caspase activity, caspase-3 activation, cleavage of poly(ADP-ribose) polymerase (PARP) and classic protein kinase C (PKC) isoforms, and DNA fragmentation. The proapoptotic role of mTOR in this process was demonstrated by the fact that rapamycin, a mTOR inhibitor, blocked p53 Ser(18) phosphorylation, the induction of PUMA, and all other apoptosis events. Furthermore, the proapoptotic function of mTOR was also antagonized by the expression in MEF3T3 cells of the PCPH oncoprotein, known to enhance cell survival by causing partial ATP depletion. Tetracyclin (Tet)-regulated expression of oncogenic PCPH, or overexpression of normal PCPH, blocked both phosphorylation and nuclear shuttling of mTOR in response to IR. These results indicate that alterations in PCPH expression may render tumor cells resistant to IR, and perhaps other DNA-damaging agents, by preventing mTOR activation and signaling.
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PMID:The PCPH oncoprotein antagonizes the proapoptotic role of the mammalian target of rapamycin in the response of normal fibroblasts to ionizing radiation. 1455 16

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

The p53 tumor suppressor gene can induce either apoptosis or a permanent growth arrest (also termed senescence) phenotype in response to cellular stresses. We show that the increase in intracellular reactive oxygen species (ROS) associated with the magnitude of p53 protein expression correlated with the induction of either senescence or apoptosis in both normal and cancer cells. ROS inhibitors ameliorated both p53-dependent cell fates, implicating ROS accumulation as an effector in each case. The absence of Bax or PUMA strongly inhibited both p53-induced apoptosis and ROS increase, indicating an important role these p53 targets affecting mitochondrial function genes in p53-mediated ROS accumulation. Moreover, physiological p53 levels in combination with an exogenous ROS source were able to convert a p53 senescence response into apoptosis. All of these findings establish a critical role of ROS accumulation and mitochondrial function in p53-dependent cell fates and show that other ROS inducers can collaborate with p53 to influence these fate decisions. Thus, our studies imply that therapeutic agents that generate ROS are more likely to be toxic for normal cells than p53-negative tumor cells and provide a rationale for identifying therapeutic agents that do not complement p53 in ROS generation to ameliorate the cytotoxic side effects in normal cells.
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PMID:Influence of induced reactive oxygen species in p53-mediated cell fate decisions. 1461 2

The current interest in expression of groups of functionally related genes creates a demand for novel experimental tools. We describe a multiplex ligation-dependent amplification procedure (RT-MLPA), which accurately quantifies up to 45 transcripts of interest in a one-tube assay. The output, a set of fluorescent DNA fragments, is analysed via capillary sequencer and spreadsheet software. The procedure is highly sensitive and reproducible over a 100-fold range of input RNA, with excellent compatibility with RT-PCR and microarrays. We targeted two comprehensive sets of human genes: 35 apoptosis regulators and 30 genes involved in inflammation. Both probe sets accurately assessed specific changes in gene expression in two relevant model systems. Stimulation of lymphocytes with various Toll-like receptor (TLR) ligands induced distinct inflammatory profiles. Furthermore, osteosarcoma cells treated with cytostatic drugs showed as primary response strong up-regulation of the apoptogenic p53-inducible PUMA transcript. Suppression by RNAi validated that indeed Puma expression was responsible for apoptosis induction. Thus, RT-MLPA enables relevant changes in transcription patterns to be quickly pinpointed and guide further experiments. This can be an advantage compared to hypothesis-free whole genome screens where large numbers of differentially expressed genes can obscure functional interpretation.
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PMID:Expression profiling via novel multiplex assay allows rapid assessment of gene regulation in defined signalling pathways. 1462 43

p73, an important developmental gene, shares a high sequence homology with p53 and induces both G(1) cell cycle arrest and apoptosis. However, the molecular mechanisms through which p73 induces apoptosis are unclear. We found that p73-induced apoptosis is mediated by PUMA (p53 up-regulated modulator of apoptosis) induction, which, in turn, causes Bax mitochondrial translocation and cytochrome c release. Overexpression of p73 isoforms promotes cell death and bax promoter transactivation in a time-dependent manner. However, the kinetics of apoptosis do not correlate with the increase of Bax protein levels. Instead, p73-induced mitochondrial translocation of Bax is kinetically compatible with the induction of cell death. p73 is localized in the nucleus and remains nuclear during the induction of cell death, indicating that the effect of p73 on Bax translocation is indirect. The ability of p73 to directly transactivate PUMA and the direct effect of PUMA on Bax conformation and mitochondrial relocalization suggest a molecular link between p73 and the mitochondrial apoptotic pathway. Our data therefore indicate that PUMA-mediated Bax mitochondrial translocation, rather than its direct transactivation, correlates with cell death. Finally, human DeltaNp73, an isoform lacking the amino-terminal transactivation domain, inhibits TAp73-induced as well as p53-induced apoptosis. The DeltaNp73 isoforms seem therefore to act as dominant negatives, repressing the PUMA/Bax system and, thus, finely tuning p73-induced apoptosis. Our findings demonstrate that p73 elicits apoptosis via the mitochondrial pathway using PUMA and Bax as mediators.
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PMID:p73 Induces apoptosis via PUMA transactivation and Bax mitochondrial translocation. 1463 23

We have used a lentiviral vector to stably express p53 at a physiological level in p53 knockout HCT116 cells. Cells transduced with wild type p53 responded to genotoxic stress by stabilizing p53 and expressing p53 target genes. The reconstituted cells underwent G(1) arrest or apoptosis appropriately depending on the type of stress, albeit less efficiently than parental wild type cells. Compared with cells expressing exogenous wild type p53, the apoptotic response to 5-fluorouracil (5FU) was >50% reduced in cells expressing S15A or S20A mutant p53, and even more reduced by combined mutation of serines 6, 9, 15, 20, 33, and 37 (N6A). Among a panel of p53 target genes tested by quantitative PCR, the gene showing the largest defect in induction by 5FU was BBC3 (PUMA), which was induced 4-fold by wild type p53 and 2-fold by the N6A mutant. Mutation of N-terminal phosphorylation sites did not prevent p53 stabilization by doxorubicin or 5FU. MDM2 silencing by RNA interference activated p53 target gene expression in normal fibroblasts but not in HCT116 cells, and exogenous p53 could be stabilized in HCT116 knockout cells despite combined mutation of p53 phosphorylation sites and silencing of MDM2 expression. The MDM2 feedback loop is thus defective, and other mechanisms must exist to regulate p53 stability and function in this widely used tumor cell line.
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PMID:Regulation of p53 stability and function in HCT116 colon cancer cells. 1466 30

The p53 gene is the most frequently mutated gene in human cancers. Loss of functional p53 leads to impaired responses of cancer cells to apoptosis induction and to poor prognosis in patients with certain types of cancer. Cancer gene therapies using ectopic expression of wild-type p53 to force cancer cells through the apoptotic pathway have been tested extensively preclinically and clinically, and genes in various cell lines have been reported to be regulated upon ectopic p53 overexpression. However, the effect of p53 on many other p53-dependent and apoptosis-related genes remains unclear, as does the mechanism of p53-induced apoptosis in human cancers. In this study, we used real-time reverse transcription polymerase chain reaction to evaluate the changes in expression of various p53-dependent and apoptosis-related genes in five human non-small-cell lung cancer cell lines with varying p53 statuses after adenoviral p53 treatment. We found that Ad/p53 induced the expression of the proapoptotic genes PUMA, Bak, Bax, and Fas in a cell type- and time-dependent manner. Among these genes, PUMA was upregulated the most dramatically and broadly. However, when a specific siRNA construct against PUMA was employed, we observed no attenuation of apoptosis in H1299 cells. Our data suggest that Ad-p53 induces the expression of a variety of proapoptotic genes and that lack of induction in one of these genes does not block Ad/p53-mediated cell killing in human lung cancer cells.
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PMID:Induction of p53-regulated genes in lung cancer cells: implications of the mechanism for adenoviral p53-mediated apoptosis. 1467 44


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