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 EP300 protein is a histone acetyltransferase that regulates transcription via chromatin remodelling and is important in the processes of cell proliferation and differentiation. EP300 acetylation of TP53 in response to DNA damage regulates its DNA-binding and transcription functions. A role for EP300 in cancer has been implied by the fact that it is targeted by viral oncoproteins, it is fused to MLL in Leukaemia and two missense sequence alterations in EP300 were identified in epithelial malignancies. Nevertheless, direct demonstration of the role of EP300 in tumorigenesis by inactivating mutations in human cancers has been lacking. Here we describe EP300 mutations, which predict a truncated protein, in 6(3%) of 193 epithelial cancers analysed. Of these six mutations, two were in primary tumours (a colorectal cancer and a breast cancer) and four were in cancer cell lines (colorectal, breast and pancreatic). In addition, we identified a somatic in-frame insertion in a primary breast cancer and missense alterations in a primary colorectal cancer and two cell lines (breast and pancreatic). Inactivation of the second allele was demonstrated in five of six cases with truncating mutations and in two other cases. Our data show that EP300 is mutated in epithelial cancers and provide the first evidence that it behaves as a classical tumour-suppressor gene.
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PMID:Mutations truncating the EP300 acetylase in human cancers. 1070 Jan 88

Through a strategy of direct cloning of TP53-binding DNA sequences from human genome DNA, we have identified a novel TP53-target gene, termed TP53TG5 (TP53-target gene 5). This gene, localized to chromosome band 20q13.1 by fluorescence in situ hybridization, encodes a 290-amino-acid peptide with no significant homology with any known proteins in the public database. A colony-formation assay using human glioblastoma cell line T98G, which lacks wild-type TP53 and expresses no endogenous TP53TG5, revealed a growth-suppressive effect of the TP53TG5 gene product. Furthermore, immunohistochemical studies, following transfection of T98G with plasmid designed to express green fluorescent protein-fused TP53TG5, revealed cell cycle-dependent intracellular localization of this protein. Our results suggest that functional studies of TP53TG5 may provide new insights into the complex physiological activities of TP53.
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PMID:Isolation and characterization of a novel TP53-inducible gene, TP53TG5, which suppresses growth and shows cell cycle-dependent transition of expression. 1071 63

The unique behavior of green fluorescent protein (GFP) on SDS-PAGE was applied to the detection of a single amino acid substitution in GFP-tagged polypeptides. This simple detection method using SDS/urea gels was designated GFP-display. The N-terminal 18 or 37 amino acids of K-Ras was used as a model GFP-tagged polypeptide. K-ras exon 1 was fused to a gfp cDNA at each end and expressed in Escherichia coli. Amino acid number 12 of K-Ras (wild type; Gly) was changed to Ser, Arg, Cys, Asp, Ala, or Val, and the mobility shift of the greenish fluorescent bands in the SDS/urea gel was analyzed. These mutants were easily detected by GFP-display; however, detection depended strongly on the urea concentration and electrophoresis temperature. Subsequently, GFP-display was applied to the 36 amino acids encoding human p53 exon 7. Amino acid number 248 (wild type; Arg) was changed to Gly, Trp, Gln, Pro, or Leu, and similar mobility shifts were observed. GFP-display could be coupled with an in vitro translation system. Fluorescent active GFP and GFP-Ras fusion proteins were synthesized within a few hours. GFP-display shows potential as a modern approach to gene mutation analysis at the protein level, and is a useful method for protein engineering studies.
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PMID:A new approach to gene mutation analysis using "GFP-Display". 1073 55

Gene therapy using vector-mediated transfer of prodrug activating genes is a promising treatment approach for malignant tumors. As demonstrated recently, the novel prodrug activating gene coding for rabbit cytochrome P450 4B1 (CYP4B1) is able to induce tumor cell death at low micromolar concentrations in glioblastoma cells after treatment with the prodrug 4-ipomeanol (4-IM) in vitro and in vivo. The rabbit CYP4B1 converts this prodrug and other furane analogs and aromatic amines, such as 2-aminoanthracene, to highly toxic alkylating metabolites, whereas the human isoenzyme exhibits only minimal enzymatic activity. In the present study, the cDNA encoding rabbit CYP4B1 was used for pharmacogene therapy of hepatocellular carcinoma (HCC). Cell clones derived from the human HCC cell lines Hep3B, HuH-7, and HepG2 and stably expressing the chimeric protein CYP4B1-EGFP (the CYP4B1 coding sequence fused to the enhanced green fluorescent protein (EGFP) gene) were selected. HCC clones expressing EGFP served as controls. 4-IM rapidly induced tumor cell death in CYP4B1-EGFP-expressing clones at low concentrations (a 50% lethal dose of between 0.5 and 2 microg/mL). No signs of toxicity were found in control cells expressing EGFP even at high prodrug concentrations (20 microg/mL). Cell death occurred by apoptosis and was independent of functional p53. A pronounced direct bystander effect was observed in Hep3B cells, whereas bystander HepG2 and HuH-7 cells were highly resistant to toxic 4-IM metabolites. These results demonstrate that the CYP4B1/4-1M system efficiently and rapidly induces cell death in HCC cells, and that a cell line-specific mechanism may exist that limits the extent of the bystander effect of this novel prodrug activating system.
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PMID:Rabbit cytochrome P450 4B1: A novel prodrug activating gene for pharmacogene therapy of hepatocellular carcinoma. 1091 3

The tumour suppressor p53 protein integrates multiple signals regulating cell cycle progression and apoptosis. This regulation is mediated by several kinases that phosphorylate specific residues in the different functional domains of the p53 molecule. The human VRK1 protein is a new kinase related to a poxvirus kinase, and more distantly to the casein kinase 1 family. We have characterized the biochemical properties of human VRK1 from HeLa cells. VRK1 has a strong autophosphorylating activity in several Ser and Thr residues. VRK-1 phosphorylates acidic proteins, such as phosvitin and casein, and basic proteins such as histone 2b and myelin basic protein. Because some transcription factors are regulated by phosphorylation, we tested as substrates the N-transactivation domains of p53 and c-Jun fused to GST. Human c-Jun is not phosphorylated by VRK1. VRK1 phosphorylates murine p53 in threonine 18. This threonine is within the p53 hydrophobic loop (residues 13-23) required for the interaction of p53 with the cleft of its inhibitor mdm-2. The VRK1 C-terminus domain (residues 268-396) that contains a nuclear localization signal targets the protein to the nucleus, as determined by using fusion proteins with the green fluorescent protein. We conclude that VRK1 is an upstream regulator of p53 that belongs to a new signalling pathway.
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PMID:The human vaccinia-related kinase 1 (VRK1) phosphorylates threonine-18 within the mdm-2 binding site of the p53 tumour suppressor protein. 1095 72

The BRCT (BRCA1 C-terminus) superfamily includes a large number of nuclear proteins closely involved in DNA repair, recombination, and cell-cycle control. The human cDNA clone NFBD1 (previously designated KIAA0170) encodes a novel protein (2089 amino acids in length; calculated molecular mass 226,440 D) with possible BRCT domains at its carboxy terminus (amino acid residues 1894-2089). This gene product has been described as one of the BRCT superfamily proteins. However, its biological significance has been unclarified. Expression of green fluorescent protein (GFP)-tagged full-length NFBD1 or a series of deletion mutants indicated that NFBD1 was localized to the nucleus in various mammalian cells, and a 197-amino acid segment near the amino terminus (amino acid residues 142-338) contained a nuclear targeting signal. In vitro DNA-binding experiments showed that the highly basic region of NFBD1 (amino acid residues 1841-1893) possessed DNA-binding activity. The region encoding amino acids 508-995 of NFBD1 fused inframe with GAL4 DNA-binding domain activated transcription in both yeast and mammalian cells, while the possible BRCT domains of NFBD1 failed to induce transcription in mammalian cells. Overexpression of antisense NFBD1 RNA in a p53-deficient human osteogenic sarcoma cell line (SAOS-2) resulted in remarkable suppression of SAOS-2 colony formation. These results suggest that NFBD1 is a nuclear transcriptional transactivator with possible BRCT domains and may contribute to cell growth control.
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PMID:NFBD1/KIAA0170 is a novel nuclear transcriptional transactivator with BRCT domain. 1097 65

In this study, immunoglobulin variable (Ig V) region genes, c-myc re-arrangement and sequence and p53 status were analyzed in clones derived from a Burkitt's lymphoma cell line (LAM) in which it was previously demonstrated that Epstein-Barr virus (EBV) infection occurred late during lymphomagenesis. Such evidence was based on the finding that 2 groups of cellular clones, characterized by the same c-myc re-arrangement but different EBV-fused termini, were obtained from the LAM cell line. The Ig V gene sequences were identical for the 2 groups of clones with different EBV-fused termini. The Ig variable heavy (V(H)) gene sequence displayed a substantial accumulation of point mutations (but no intra-clonal diversification), whereas the productive Ig V lambda (V(lambda)) gene sequence was virtually unmutated. Studies on the Ig V kappa (V(kappa)) locus suggested a receptor revision event (with a switch from kappa to lambda chain production) prior to EBV infection. Likewise, it was determined that the mutations observed in both p53 alleles and in the re-arranged c-myc gene occurred before EBV infection. Based on these findings, we present a model for the various steps of lymphomagenesis. It is proposed that stimulation by an antigen or a superantigen initially favored the clonal expansion and accumulation of other cytogenetic changes, including those involved in receptor editing. These events occurred prior to or during the germinal center (GC) phase of B-cell maturation. Thereafter, possibly upon exit of the cells from the GC, EBV infection occurred, further promoting lymphomagenesis.
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PMID:Analysis of stepwise genetic changes in an AIDS-related Burkitt's lymphoma. 1107 43

The human papillomaviruses (HPV)-16 and HPV-18 referred to as high-risk HPVs are strongly associated with anogenital malignancies as well as benign epithelial cysts. It has been demonstrated that transgenic mice carrying HPV-16 E6-E7 under the control of the MMTV LTR developed malignant tumors including salivary gland carcinoma, lymphoma, skin histiocytomas and testicular tumors in a non-mammary gland specific manner. Another regulatory unit of rat beta-casein gene can confer the expression of fusion gene preferentially in the mammary glands of transgenic mice in a developmentally regulated manner. In order to generate mammary tumor formation in transgenic mice directing HPV16E6 gene alone into the mammary gland, this regulatory unit was fused to the E6 gene of HPV-16 type to constructing fusion gene. By screening 51 newborn founder transgenic mice, three mice carrying transgenes were identified. One line termed TG32 developed in a mammary gland tumor with large subcutaneous mass in the left rib region at 17 months of age. The levels of E6 transcript in the mass-tumor of TG32 line were lower than those in non-tumor mammary gland of identical TG32 and of TG250. In each tissue of TG32 line, high expression of E6 transcript was detected both in the mammary gland and brain. Histological analysis showed that cells from mammary gland tumor of the TG32 line had also hyperplasia appearance, with irregular or increased total number of mitotic rate. These observations suggest that developing phenotype and the level of E6 transcripts in the process of malignant transformation may have different mechanisms involving the capacity to bind and destabilize p53, although for confirmation it is necessary to investigate many more transgenic mice.
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PMID:Mammary gland tumor in transgenic mice expressing targeted beta-casein/HPV16E6 fusion gene. 1107 93

The Helicobacter pylori toxin VacA induces intracellular vacuolation and plays an essential role in H. pylori-related diseases. The mature exotoxin is divided into two domains, P37 and P58. A soluble form of VacA fused with GST was expressed in Escherichia coli. Although the soluble fusion lacked vacuolating activity after cleavage by thrombin, it had a binding affinity similar to that of the native VacA. Moreover, it blocked the vacuolating activity induced by the native toxin. Different C-terminal truncated fusions were generated (GST-P72, GST-P53, and GST-P37) and were also produced in a soluble form. A significantly reduced binding activity was seen for GST-P72 and nearly no specific association was detected for GST-P37. Our results suggested that the whole P58 fragment contributed to the cell binding activity in HeLa cells, particularly in the C-terminal approximately 100-residue region.
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PMID:Expression and binding analysis of GST-VacA fusions reveals that the C-terminal approximately 100-residue segment of exotoxin is crucial for binding in HeLa cells. 1109 57

Nuclear domains called ND10 or PML nuclear bodies consist of an aggregation of several proteins, most notably PML and Sp100. PML is essential in the nucleation and formation of ND10 as well as in the recruitment of other ND10-associated proteins such as Daxx, pRb, BLM and Sp100. In cells induced to overexpress Sp100, ND10 binding of Sp100 was saturable and excess Sp100 formed new aggregation sites devoid of other ND10-associated proteins, suggesting that homo-oligomerization is the basis for aggregation. To determine whether Sp100 binds to ND10 through hetero- or oligomerization, Sp100 deletion variants fused with GFP were transfected into cells with and without endogenous Sp100, and the localization of the GFP-labeled fragments was determined relative to ND10. Amino acids 29-152 were sufficient for deposition of the GFP-labeled fragments at ND10 in the absence of endogenous Sp100 (heterologous binding) and for self-aggregation (formation of new Sp100 deposits). None of the shorter fragments was deposited at ND10 or self-aggregated. The 29-152 amino acid fragment and some larger fragments, but not the full-size Sp100, induced elongation of ND10, which at their ends contain only Sp100, probably due to self-aggregation. By fusing a peptide consisting of the p53-binding domain from hMDM2 to the Sp100(29-152) fragment, this self-aggregation could be blocked while retaining the limited ND10 binding capacity, indicating that the Sp100 self-aggregation domain and the ND10 binding domain are separate entities. This fusion peptide was used to demonstrate the potential of ND10 to recruit p53 as a protein not usually present at this site. Such deposited p53 was protected from turnover. The capacity of ND10 to recruit Sp100 may serve primarily to reduce its availability.
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PMID:Evidence for separate ND10-binding and homo-oligomerization domains of Sp100. 1111 90


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