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)

The tumor suppressor protein p53 is a metal-binding transcription factor whose conformation and function are altered by mutation in cancers. Using murine p53 translated in vitro, we report here that concentrations of copper within the physiological range (< 30 microM) alter the conformation of wild-type p53 and inhibit sequence-specific DNA-binding. Direct binding of copper to p53 in the form of Cu(I) was demonstrated by Electron Spin Resonance using a purified recombinant protein containing residues 1-343 of murine wild-type p53 fused to E. coli maltose binding protein. Moreover, protection against the effect of Cu(II) sulfate was achieved by the Cu(I)-specific chelator bathocuproinedisulfonic acid but not by scavengers of reactive oxygen species, suggesting that alteration of p53 by copper depends upon a Cu(II)/Cu(I) redox mechanism, but does not require the production of reactive oxygen species. Thus copper at physiological concentrations can interact with wild-type p53 and affect its DNA-binding capacity.
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PMID:Modulation by copper of p53 conformation and sequence-specific DNA binding: role for Cu(II)/Cu(I) redox mechanism. 782 76

Oxidative DNA damage by NAD(P)H in the presence of metal ions has been characterized by using 32P 5' end-labeled DNA fragments obtained from human p53 tumor suppressor gene and c-Ha-ras-1 protooncogene. NADH, as well as other endogenous reductants, induced DNA damage in the presence of Cu(II). The order of inducing effect on Cu(II)-dependent DNA damage was ascorbate > reduced glutathione (GSH) > NADH > NADPH. Although NADH caused no or little DNA damage in the presence of Fe(III)-EDTA, the addition of H2O2 induced the DNA damage. The Cu(II)-mediated DNA damage induced by NADH was inhibited by catalase and bathocuproine, a Cu(I)-specific chelator; but not by scavengers of hydroxyl free radical (.OH), suggesting the involvement of active species derived from hydrogen peroxide (H2O2) and Cu(I) rather than .OH. The predominant cleavage sites were thymine residues located 5' and/or 3' to guanine. The cleavage pattern was similar to that induced by Cu(II) plus GSH, Cu(II) plus ascorbate, or Cu(I) plus H2O2. Formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine by NADH increased with its concentration in the presence of Cu(II). UV-visible spectroscopy indicated the facilitation of reduction of Cu(II) by NADH under some conditions. ESR spin-trapping experiments and mass spectrometry showed that the carbon-centered radical was formed during the reaction of NADH with Cu(II). These results suggest that optimal molar ratios of DNA/metal ion yield copper with a high redox potential which catalyzes NADH autoxidation to NAD. being further oxidized to NAD+ with generation of superoxide radical and that H2O2 reacts with Cu(I) to form active oxygen species such as copper(I)-peroxide complex causing DNA damage.
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PMID:Site-specific DNA damage induced by NADH in the presence of copper(II): role of active oxygen species. 860 9

We have discovered that the ability of the tumor suppressor protein p53 to bind to the viral large T antigen (TAg) oncogene product is regulated by divalent cations. Both proteins were purified from an insect cell line infected with the appropriate baculovirus expression vector. In a two-site capture enzyme-linked immunosorbent assay, complex formation between the purified proteins is strictly dependent on the addition of specific concentrations of divalent metal ions, notably zinc, copper, cadmium, cobalt, manganese, and nickel. In the presence of zinc the pattern of proteolytic fragments obtained when TAg was subjected to proteolysis by endoproteinase Glu-C (V8) was strikingly different, supporting the idea that a conformational change in TAg associated with ion binding is required for it to complex with p53. Monoclonal antibody analysis provides supporting evidence for a conformational change. When TAg was captured onto an enzyme-linked immunosorbent assay plate coated with PAb 419 as opposed to many other anti-TAg antibodies, complex formation was completely independent of the presence of additional divalent cations. Our results suggest that the ability of p53 and TAg to form a stable complex in vitro is dependent upon a regulatory domain residing in the N terminus of TAg, zinc ions or the binding of a specific monoclonal antibody (PAb 419) provoking a conformational change in TAg that facilitates and supports complex formation.
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PMID:Modification of an N-terminal regulatory domain of T antigen restores p53-T antigen complex formation in the absence of an essential metal ion cofactor. 861 69

The pathogenesis of copper (Cu)-induced liver injury has been investigated in Bedlington terriers with familial Cu toxicosis using ultrastructural and microanalytical techniques. Livers from 3 affected and 1 non-affected Bedlington terrier were fixed in 4% paraformaldehyde and 2% glutaraldehyde for transmission electron microscopy and X-ray electron probe microanalysis. Cu analysis was performed on formalin fixed liver by atomic absorption spectrophotometry. In the dog with liver Cu concentration < 2000 micrograms/g, Cu was located only in electron dense lysosomes with minimal cytoplasmic change. With increasing concentrations of liver Cu, the metal became apparent in the nucleus with early signs of nuclear disturbance. In the dog with highest liver Cu content > 7000 micrograms/g X-ray microanalysis identified Cu peaks in lysosomes, nucleus and cytoplasm in descending order with profound cellular changes. The hepatocytes were shrunken with compacted electron dense organelles and the nuclei were contracted, misshapen with chromatin condensation and fragmentation. Apoptotic bodies were identified in sinusoids. It was concluded that excess Cu is initially sequestered in lysosomes but following increasing saturation of this compartment nuclear accumulation of Cu occurs with DNA damage. Apoptosis follows probably by induction of p53 protein.
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PMID:Pathobiology of copper-induced injury in Bedlington terriers: ultrastructural and microanalytical studies. 879 84

The LEC rat is an inbred mutant strain which spontaneously develops liver injury and subsequent liver cancer. Liver injury in LEC rats has recently been shown to be closely related to abnormal copper accumulation in the liver. Previously, we reported that LEC rat hepatocytes lose their growth potential, probably allowing selective growth of preneoplastic cells. In this study, to elucidate the effects of copper accumulation on the growth activity of LEC rat hepatocytes, we examined the growth activity and the expression of p53 and p21(waf 1/cip 1) in the livers of LEC rats fed on either a control or a low-copper diet. Potential for cell proliferation of hepatocytes obtained from normal diet fed LEC rats was almost comparable to that of the cells from age-matched Sprague-Dawley (SD) rats. Northern blot analysis showed that the expression of p53 and p21(waf 1/cip 1) was significantly high in the livers of LEC rats fed a control diet, while the expression of p53 and p21(waf 1/cip 1) in the LEC rats fed a low-copper diet was as low as that of SD rat livers. Western blot analysis consistently showed that the amount of p21(waf 1/cip 1) bound to the nuclear matrix scaffold of the LEC rat liver was reduced by feeding a low-copper diet. These findings suggest that abnormal accumulation of copper induced the expression of p53 and p21(waf 1/cip 1), resulting in the inhibition of cell proliferation of LEC rat hepatocytes.
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PMID:Abnormal accumulation of copper in LEC rat liver induces expression of p53 and nuclear matrix-bound p21(waf 1/cip 1). 889 83

The frequency of oxidative base damage along the human p53 and PGK1 genes was determined at nucleotide resolution by cleaving DNA at oxidized bases with endonuclease III and formamidopyrimidine DNA glycosylase and then using the ligation-mediated PCR technique to map induced break frequency. Damage was induced either in vivo by exposing cultured human male fibroblasts to H2O2 or in vitro by exposing purified genomic DNA to H2O2 plus ascorbate in the presence of Cu(II), Fe(III), or Cr(VI) metal ions. All four base damage patterns from either in vivo or in vitro treatments were nearly identical in both regions of the genome. The frequency of base damage varied along the DNA, with guanine being the most commonly damaged base. In the Fe(III)-mediated in vitro reactions, single-stranded breaks were almost completely suppressed by addition of sucrose, which facilitated mapping of base damage. The in vitro base damage pattern generated by Cr(VI), ascorbate, and H2O2 was similar to that of the other metal ions, with the exception of several unique positions; these were heavily damaged only in the presence of Cr(VI). Isolated nuclei suffered little oxidative base damage in the presence of ascorbate and H2O2, and we conclude that during H2O2 in vivo treatment of cells, metal ions (or metal-like ligands) are freed from the cytoplasm to migrate into the nucleus and supply the redox cycling ligands necessary for oxidative base damage. These data simplify the complexity of H2O2-induced oxidative damage and mutagenesis studies by demonstrating the commonality of damage catalyzed by different transition metal ions and by showing that the pattern of H2O2-mediated oxidative base damage is determined almost entirely by the primary DNA sequence, with chromatin structure having a limited effect. Our data suggest a model for base damage in which DNA-metal ion binding domains can equally accommodate a variety of different metal ions and thus are a key factor in determining the local probability of DNA damage.
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PMID:Metal ion-dependent hydrogen peroxide-induced DNA damage is more sequence specific than metal specific. 919 16

Mutations in the p53 tumor suppressor gene frequently fall within the specific DNA-binding domain and prevent the molecule from transactivating normal targets. DNA-binding activity is regulated in vitro by metal ions and by redox conditions, but whether these factors also regulate p53 in vivo is unclear. To address this question, we have analyzed the effect of pyrrolidine dithiocarbamate (PDTC) on p53 DNA-binding activity in cell lines expressing wild-type p53. PDTC is commonly regarded as an antioxidant, but it can also bind and transport external copper ions into cells and thus exert either pro- or antioxidant effects in different situations. We report that PDTC, but not N-acetyl-L-cysteine, down-regulated the specific DNA-binding activity of p53. Loss of DNA binding correlated with disruption of the immunologically "wild-type" p53 conformation. Using different chelators to interfere with copper transport by PDTC, we found that bathocuproinedisulfonic acid (BCS), a non-cell-permeable chelator of Cu1+, prevented both copper import and p53 down-regulation. In contrast, 1,10-orthophenanthroline, a cell-permeable chelator of Cu2+, promoted the redox activity of copper and up-regulated p53 DNA-binding activity through a DNA damage-dependent pathway. We have previously reported that p53 protein binds copper in vitro in the form of Cu1+ (P. Hainaut, N. Rolley, M. Davies, and J. Milner, Oncogene 10:27-32, 1995). The data reported here indicate that intracellular levels and redox activity of copper are critical for p53 protein conformation and DNA-binding activity and suggest that copper ions may participate in the physiological control of p53 function.
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PMID:Regulation of p53 by metal ions and by antioxidants: dithiocarbamate down-regulates p53 DNA-binding activity by increasing the intracellular level of copper. 931 28

2,5-Dimethyl-4-hydroxy-3(2H)-furanone (2,5-DMHF), a caramel-like fragrant compound found in may processed foodstuff, has been reported to be mutagenic. 4,5-Dimethyl-3-hydroxy-2(5H)-furanone (4,5-DMHF), which is a similar characteristic fragrant compound, has no report concerning its mutagenicity. DNA damage by 2,5-DMHF and 4,5-DMHF was investigated by using DNA fragments obtained from the p53 tumor suppressor gene. 2,5-DMHF induced DNA damage extensively in the presence of Cu(II), but only slightly in the presence of Fe(III). 4,5-DMHF did not cause metal-dependent DNA damage. Bathocuproine, a Cu(I)-specific chelator, and catalase inhibited DNA damage induced by 2,5-DMHF plus Cu(II), whereas free hydroxyl radical scavengers did not. The order of DNA cleavage sites was thymine, cytosine > guanine residues. The site-specific DNA damage and effects of scavengers show that DNA-copper-oxygen complex rather than free .OH are involved in the DNA damage. Formation of 8-oxodeoxyguanosine (8-oxodG) by 2,5-DMHF increased with its concentration in the presence of Cu(II), whereas 8-oxodG formation increased only slightly in the presence of Fe(III). Degradation of 2,5-DMHF was efficiently accelerated by Cu(II), but only slightly accelerated by Fe(III). The degradation of 4,5-DMHF was little even in the presence of metal ions. Examination using cytochrome c suggest that superoxide was generated from 2,5-DMHF. Stoichiometric study of Cu(II) reduction revealed that autoxidation of 2,5-DMHF could offer 4-electron reduction. These results suggest that, at least in vitro and in an acellular system, 2,5-DMHF generates superoxide and subsequently hydrogen peroxide to induce metal-dependent DNA damage.
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PMID:Superoxide formation and DNA damage induced by a fragrant furanone in the presence of copper(II). 954 43

Two hair dye components, carcinogenic 4-nitro-2-aminophenol and 5-nitro-2-aminophenol, induced Cu(II)-dependent DNA cleavage frequently at thymine and guanine residues in DNA fragments obtained from the c-Ha-ras-1 protooncogene. When the p53 tumor suppressor gene was used, 4-nitro-2-aminophenol caused Cu(II)-dependent piperidine-labile sites at poly G sequences. In the presence of Cu(II), both components increased 8-oxo-7,8-dihydro-2'-deoxyguanosine formation in DNA. The inhibitory effects of catalase and bathocuproine on DNA damage suggest the involvement of H2O2 and Cu(I). It is speculated that nitro-2-aminophenols undergo Cu(II)-mediated autoxidation to generate active oxygen species causing DNA damage which leads to their carcinogenesis.
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PMID:Metal-mediated oxidative DNA damage induced by nitro-2-aminophenols. 956 50

We examined the mechanism of DNA damage induced by a mutagenic tyrosine metabolite, homogentisic acid (HGA), using 32P-5'-end-labeled DNA fragments obtained from the human p53 tumor suppressor gene. HGA caused DNA damage in the presence of Cu(II), particularly at thymine and cytosine residues. Catalase and bathocuproine inhibited the DNA damage, suggesting the involvement of H2O2 and Cu(I). The formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine by HGA increased depending on HGA concentration in the presence of Cu(II). It is concluded that H2O2 is generated during Cu(II)-catalyzed HGA autoxidation and reacts with Cu(I) to form the Cu(I)-peroxide complex, capable of causing oxidative DNA damage.
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PMID:Oxidative DNA damage induced by homogentisic acid, a tyrosine metabolite. 971 Feb 41


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