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)

Ubiquitin-carrier proteins (E2s, ubiquitin-conjugating enzymes, UBCs) participate in proteolysis by catalyzing transfer of activated ubiquitin to the protein substrates, which are bound to specific ubiquitin-protein ligases (E3s). Yeast UBC2 (RAD6) and the mammalian E2(14kDa) bind to the ligase that recognizes and is involved in the degradation of certain free amino-terminal substrates ("N-end rule" substrates). As such proteins are rather scarce, the role of these E2s in general proteolysis is probably limited. Here, we report the purification and characterization of a novel 18-kDa species of E2 from rabbit reticulocytes. Unlike most members of the E2 family, this enzyme does not adsorb to anion exchange resin in neutral pH, and it is purified from the unadsorbed material (Fraction 1). Thus, it is designated E2-F1. Like all members of the E2 family, it generates a thiol ester with ubiquitin that serves as an intermediate in the conjugation reaction. Sequence analysis revealed a significant homology to many known species of E2s. The enzyme generates multiply ubiquitinated proteins in the presence of an E3 that has not been characterized yet. Most importantly, the ubiquitination via this E2 leads to the degradation of certain non-"N-end rule" substrates such as glyceraldehyde-3-phosphate dehydrogenase (Val at the NH2 terminus) and to the ubiquitination and degradation of certain N-alpha-acetylated proteins such as histone H2A, actin, and alpha-crystallin. The enzyme is also involved in the conjugation and degradation of the tumor suppressor protein p53.
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PMID:Purification and characterization of a novel species of ubiquitin-carrier protein, E2, that is involved in degradation of non-"N-end rule" protein substrates. 814 44

Reverse transcription polymerase chain reaction (RT-PCR) was performed to evaluate the sequential alteration of proto-oncogene mRNA expression in liver, spleen, kidney and brain of mice after whole body irradiation (WBI). The mRNAs investigated in this study were Fas, c-fos, c-myc. bcl-2, and p53, and glyceraldehyde-3-phosphate dehydrogenase mRNA was employed as internal control. C3H/He mice aged 9-10 weeks were exposed to WBI of 7 Gy using a cobalt-60 teletherapy unit, without anesthesia, and sacrificed before and 0.1, 0.5, 1, 2, 3, 6, 12, 24, 48 and 96 h after irradiation. Their liver, spleen, kidney and brain were taken and immediately stored in liquid nitrogen until ready for RT-PCR. Each specimen was homogenized to extract RNA for conventional RT-PCR. The liver of mice administered 7 Gy of WBI revealed no significant changes in the expression of each of the mRNAs examined. In the spleen, c-fos mRNA expression decreased at 2 h following irradiation, and increased remarkably thereafter. In the kidney, no significant change in the expression of each mRNA was shown. In the brain c-fos mRNA expression decreased 1-24 h after irradiation, and showed a recovery thereafter. The remarkable differences in the sequential changes of c-fos mRNA expression following irradiation between each organ revealed by the present experiment may be an important aid in determining the tissue-specific radiosensitivity to ionizing radiation. Further investigations are, however, needed to clarify the signal transduction mechanisms which are mediated by the expression of these proto-oncogenes in each tissue following irradiation.
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PMID:Sequential alteration of proto-oncogene expression in liver, spleen, kidney and brain of mice subjected to whole body irradiation. 878 77

Wild-type p53 (wtp53) is a tumour suppressor gene involved in cell cycle regulation. The mdm2 protein can complex with the p53 protein and influence its function as a regulator of cell growth. To detect and quantify wtp53 and mdm2 mRNA expression, we established the competitive reverse transcription/polymerase chain reaction for these genes and for the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The target RNA differed from the competitor cRNA by having 183 bp, 205 bp and 173 bp deletions for p53, mdm2 and GAPDH, respectively. Target RNA and known concentrations of competitor cRNA were co-reverse transcribed and co-amplified with the same primers. Target cDNA and the corresponding competitor cDNA were amplified at the same efficiency.
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PMID:Competitive reverse transcription/polymerase chain reaction for the quantification of p53 and mdm2 mRNA expression. 902 80

NO is believed to be involved in neurotoxicity after various neuronal stresses. NO donors are toxic and cause changes in cellular morphology such as condensed and fragmented chromatin, shriveled nuclei, apoptotic bodies and membrane blebbing. These observations are consistent with the overall description of apoptosis. The crucial mechanism of NO-induced cytotoxicity is still unclear. Several mechanisms for NO-induced cytotoxicity in neurons have been proposed. It has been reported that NO enhances ADP-ribosylation or S-nitrosylation of an increasing number of proteins, and two of these proteins were identified as NO-target proteins. One is glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a key enzyme of glycolytic conversion, which is S-nitrosylated by NO inhibiting the enzyme activity. Hence, inhibition of GAPDH activity by NO would decrease the amount of ATP. NO also activates poly (ADP-ribose) polymerase (PARP) in the presence of DNA damage. The activation of PARP results in depletion of NAD and ATP. The energy depletion by NO could cause cell death. Recently, several factors such as Fas, the caspases (interleukin-1 beta-converting enzyme (ICE)-like proteases), Bcl-2 and the tumor suppressor gene product p53 have been shown to be involved in apoptotic cell death. We here discuss the crucial mechanisms of NO-induced cytotoxicity and also discuss recent findings about the protective effect of NO on cell death.
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PMID:[The precise characterization and the crucial mechanism of NO-induced cytotoxicity]. 979 73

We recently reported that cytosine arabinoside (AraC)-induced apoptosis of cerebellar neurons involves the overexpression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The present study was undertaken to investigate whether p53 and/or Bax overexpression participates in the AraC-induced apoptosis of cerebellar granule cells and, if so, the relationship between p53 induction and GAPDH overexpression in these cells. AraC-induced apoptosis of cerebellar granule cells was preceded by an increase in levels of p53 mRNA and protein detected between 1 and 8 hr after treatment. The mRNA level for a p53 target gene, Bax, was also increased. The increase in GAPDH mRNA lasted longer than that of either p53 or Bax, and the level of GAPDH protein in the particulate fraction increased after induction of GAPDH mRNA. The antisense oligonucleotide to p53 protected granule cells from AraC-induced chromatin condensation, internucleosomal cleavage, and apoptotic death. The inhibition of p53 expression by the p53 antisense oligonucleotide not only blocked the expression of Bax but also partially suppressed the increased GAPDH mRNA and protein levels. Conversely, the suppression of GAPDH expression and subsequent attenuation of apoptosis of granule cells by GAPDH antisense oligonucleotide did not influence the expression of p53 or Bax. Cerebellar granule cells prepared from p53 knock-out mice were resistant to AraC toxicity, and the p53 gene knock-out suppressed AraC-upregulated GAPDH expression. Moreover, infection of PC12 cells with an adenoviral vector containing p53 gene dramatically increased GAPDH expression and triggered cell apoptosis. These results suggest that AraC-induced apoptosis of cerebellar granule cells involves the expression of both GAPDH and p53 and that, similar to Bax, GAPDH is upregulated by p53 after exposure to the apoptotic insult.
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PMID:Involvement of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and p53 in neuronal apoptosis: evidence that GAPDH is upregulated by p53. 1053 67

Protein transport in the early secretory pathway requires Rab2 GTPase. This protein promotes the recruitment of soluble components that participate in protein sorting and recycling from pre-Golgi intermediates (vesicular tubular clusters (VTCs)). We previously reported that a constitutively activated form of Rab2 (Q65L) as well as Rab2 wild type promoted vesicle formation from VTCs. These vesicles contained Rab2, beta-COP, p53/gp58, and protein kinase Ciota/lambda but lacked anterograde-directed cargo. To identify other candidate Rab2 effectors, the polypeptide composition of the vesicles was further analyzed. We found that vesicles released in response to Rab2 also contained the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). To study the relationship of this enzyme to Rab2 function, we performed a quantitative binding assay to measure recruitment of GAPDH to membrane when incubated with Rab2. Rab2-treated microsomes showed a 5-10-fold increase in the level of membrane-associated GAPDH. We generated an affinity-purified anti-GAPDH polyclonal to study the biochemical role of GAPDH in the early secretory pathway. The antibody arrests transport of a reporter molecule in an assay that reconstitutes ER to Golgi traffic. Furthermore, the affinity-purified antibody blocked the ability of Rab2 to recruit GAPDH to membrane. However, the antibody did not interfere with Rab2 stimulated vesicle release. These data suggest that GAPDH is required for ER to Golgi transport. We propose that membranes incubated with anti-GAPDH and Rab2 form "dead end" vesicles that are unable to transport and fuse with the acceptor compartment.
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PMID:Glyceraldehyde-3-phosphate dehydrogenase is required for vesicular transport in the early secretory pathway. 1103 21

Induction of p53 by DNA damage results in apoptosis of teratocarcinoma cells, whereas MDM2, encoded by a p53-responsive gene, can reverse this phenotype by inhibiting p53 function. Here we report that UV (10 or 20 J/m2), but not gamma irradiation (7 or 10 Gy), caused a massive apoptosis of human teratoma Tera-2 or murine testicular carcinoma F9 cells, both of which contain wild-type p53, but not murine p53 null testicular carcinoma EB-16 cells. Most Tera-2 or F9 cells died overnight after UV but not gamma irradiation. Correlated with this phenotype was a dramatic and continuing accumulation of p53 proteins after UV but not gamma irradiation. This was attributable to UV-responsive repression of MDM2 expression, because both its protein and RNA were not detectable after UV irradiation. This UV-induced repression appeared to be specific to MDM2, because expression of other genes, such as p21, p53, or glyceraldehyde-3-phosphate dehydrogenase, was not reduced. Also, RNase protection analysis showed that a DNA region, excluding the p53 binding site, in the MDM2 promoter mediated transcriptional repression in response to UV. Thus, these results suggest that UV but not gamma irradiation can induce p53 by suppressing MDM2 expression in a p53-independent fashion and subsequently, massive cell death.
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PMID:UV but not gamma irradiation accelerates p53-induced apoptosis of teratocarcinoma cells by repressing MDM2 transcription. 1108 43

In 1998 we reported that an L-peptide derived from H1 of c-Myc (Int-H1-S6A,F8A), linked to an internalization sequence from the third a-helix of Antennapedia, was endowed with an antiproliferative and proapoptotic activity toward a human mammary cancer cell line: The activity apparently depends upon the presence of the Myc motif. In the present work we have added new dimensions to our original findings. It is known that short retro-inverso (RI-) peptides can assume a 3D conformation very close to their corresponding L-forms and can be recognized by the same monoclonal antibody. We synthesized a RI-peptide form of our original L-peptide: It was much more resistant to serum peptidases than the original molecule (a half life of days rather than hours); in addition, the RI-form of the original Antennapedia internalization sequence was perfectly capable of carrying a D-peptide into human cells. We have studied three different potentially active peptides. L-peptides: Int-H1wt, Int-H1-S6A,F8A. D-peptides: RI-Int -H1-S6A,F8A. We have also studied three presumed control peptides: Int and RI-Int (no H1 motif), H1-S6A,F8A (no internalization sequence). Both 'active' and 'control' peptides have essentially confirmed our expectations, however, in cells treated with the higher concentration (10 mM) of the control peptide RI-Int, non-Myc related side effects could be detected. In order to investigate whether the antiproliferative activities displayed by some of our molecules were indeed related to an interference with the role of c-Myc (and molecules of the family), we chose an iso-amphipathic modified peptide of the H1 motif, with a proximity coefficient >50% and where the major change was at position 7 (F-->A). From a family of 73 H1 motifs belonging to (H1-Loop-H2) hu man sequences, the smallest evolutionary distance from our reference peptide was observed for the H1 of N-Myc, L-Myc, c-Myc, H1-S6A,F8A of c-Myc, and Max, in that order. Our reference peptide was therefore appropriate as a check of whether we were indeed observing activities related to Myc functions. Both Int-H1isoamph and the corresponding RI-Int-H1isoamph peptide were synthesized and studied. In terms of biological targets, we added to the human mammary cancer line of our previous work (MCF-7 cells) a colon cancer line (HCT-116 cells) and also a system of normal cells: human peripheral blood lymphocytes (PBLs) stimulated with phytohemoagglutinin (PHA). Peptides carrying an iso-amphipathic-modified H1 sequence were always very clearly (3-10 times) less active than the corresponding peptides carrying a conserved "H1 of Myc" motif. This finding was noted in five independent situations (all the cellular models considered at the present time): MCF-7 cells treated with L-peptides; MCF-7 cells treated with RI-peptides; HCT-116 cells treated with L-peptides; PBLs treated with L-peptides; PBLs treated with RI-peptides. Modulation of transcription levels of ornithine decarboxylase (ODC), p53, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), in PBLs treated with our different molecules, was well compatible with an interference by our active peptides at the level of Myc transcriptional activity. We had already reported a similar observation in MCF-7 cells. On a molar basis, RI-peptides were about 5-10 times more potent and 30-35 times more stable in complete culture medium, than their corresponding L-forms. RI-Int can probably internalize longer peptido-mimetic molecules (for instance molecules mimetic of (H1-Loop-H2), or even more. These possibilities open the way to rodent studies and to more potent/selective Myc inhibitors-two steps closer to a potential drug.
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PMID:A retro-inverso peptide homologous to helix 1 of c-Myc is a potent and specific inhibitor of proliferation in different cellular systems. 1109 87

Orphan receptors that couple to G protein without known ligands are considered to relate directly to drug discovery. Here, we examine the expression of various orphan receptors in H9c2 cells during ischemic hypoxia and reoxygenation. Among orphan receptors examined, the level of G protein-coupled receptor 41 (GPR41) mRNA increases significantly, with a peak at 2 h after reoxygenation, and recovers to the control level by 3 h after reoxygenation. The level of glyceraldehyde-3-phosphate dehydrogenase mRNA used as an internal control remains almost constant. The levels of c-fos and c-jun mRNA increase significantly with ischemic hypoxia and reoxygenation. The transfection of GPR41 into H9c2 cells results in a significant decrease in cell number, with DNA fragmentation observed by in vitro and in situ assay. The amount of p53 protein increases significantly in the nuclei of cells expressing GPR41, accompanying an increase in the transcriptional activity of p53. Consistent with the activation of p53, the level of bax mRNA is significantly increased, which leads to an increase in Bax protein. Furthermore, the expression of a deletion mutant of a GPR41, which lacks the G protein binding site and shows an attenuation of intracellular phosphorylation signals to H9c2 cells, inhibits cell death and the increase in p53 protein within 24 h after reoxygenation. These observations demonstrate that GPR41 is a novel receptor that activates p53 leading to apoptosis during reoxygenation after ischemic hypoxia in H9c2 cells. We have designated GPR41 as the hypoxia-induced apoptosis receptor, HIA-R.
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PMID:Orphan G protein-coupled receptor, GPR41, induces apoptosis via a p53/Bax pathway during ischemic hypoxia and reoxygenation. 1133 18

Huntington's disease (HD) is a hereditary neurodegenerative condition caused by a characteristic mutation in the huntingtin (htt) gene. This gene was identified in 1993. Both the mitochondria and the nucleus play an important role in HD pathology. However, the precise molecular mechanisms remain unclear. A key strategy for understanding HD pathology is to identify signaling cascades initiated by mutant Htt that lead to neuronal cell death and dysfunction. Apoptotic stress induces greater mitochondrial depolarization in HD lymphoblasts than in control subjects. This leads to overactivation of caspase-3, which is capable of cleaving htt. Truncated forms of Htt, which are similar to the caspase-cleaved products in size, exist in the nucleus of HD patient and animal model brains. We hypothesize that caspases, which are activated by mitochondrial depolarization, play a role in producing truncated forms of Htt, which accumulate in the nucleus. Truncated forms of mutant Htt that accumulate in the nucleus are toxic to cells. There is growing evidence that truncated forms of mutant Htt in the nucleus influence gene transcription by binding to proteins such as CREB binding protein (CBP) response element binding protein binding protein, N-COR, glyceraldehyde-3-phosphate dehydrogenase, and p53. p53 regulates the transcription of various mitochondrial proteins which may underlie the mitochondrial abnormalities, especially the vulnerability to mitochondrial depolarization, seen in HD tissues. Taken together, we hypothesize a noxious signaling cascade between the mitochondria and the nucleus, initiated by mutant Htt, which may underlie HD pathology.
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PMID:Mechanisms for neuronal cell death and dysfunction in Huntington's disease: pathological cross-talk between the nucleus and the mitochondria? 1146 59


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