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 protein kinase MST1 is proapoptotic when overexpressed in an active form, however, its physiologic regulation and cellular targets are unknown. An overexpressed inactive MST1 mutant associates in COS-7 cells with an endogenous 761-amino acid polypeptide known as "death-associated protein 4" (DAP4). The DAPs are a functionally heterogeneous array of polypeptides previously isolated by Kimchi and colleagues (Kimchi, A. (1998) Biochim. Biophys. Acta 1377, F13-F33 in a screen for elements involved in the interferon gamma-induced apoptosis of HeLa cells. DAP4, which is encoded by a member of a vertebrate-only gene family, contains no identifiable domains, but is identical over its amino-terminal 488 amino acids to p52(rIPK), a putative modulator of protein kinase R. DAP4 is a widely expressed, constitutively nuclear polypeptide that homodimerizes through its amino terminus and binds MST1 through its carboxyl-terminal segment. MST1 is predominantly cytoplasmic, but cycles continuously through the nucleus, as evidenced by its rapid accumulation in the nucleus after addition of the Crm1 inhibitor, leptomycin B. Overexpression of DAP4 does not cause apoptosis, however, coexpression of DAP4 with a submaximal amount of MST1 enhances MST1-induced apoptosis in a dose-dependent fashion. DAP4 is not significantly phosphorylated by MST1 nor does it alter MST1 kinase activity in vivo or in vitro. MST1-induced apoptosis is suppressed by a dominant interfering mutant of p53. MST1 is unable to directly phosphorylate p53, however, DAP4 binds endogenous and recombinant p53. DAP4 may promote MST1-induced apoptosis by enabling colocalization of MST with p53.
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PMID:Death-associated protein 4 binds MST1 and augments MST1-induced apoptosis. 1238 12

The astrocytomas represent the most common primary tumors of the brain. Despite efforts to improve the treatment of astrocytomas, these tumors and in particular the high-grade astrocytoma termed glioblastoma multiforme still carry a poor prognosis. In recent years, there has been an intensive effort to gain an understanding of the cellular and molecular mechanisms that contribute to the pathogenesis of astrocytomas as a first step toward the development of better treatments for these devastating tumors. Here, we will review our current understanding of the signaling pathways that underlie glial transformation. Studies of astrocytomas have led to the identification of two major groups of signaling proteins whose abnormalities contribute to gliomagenesis: the cell cycle pathways and the growth factor-regulated signaling pathways. Among the cell cycle proteins, the p16-cdk4-pRb and ARF-MDM2-p53 cell cycle arrest pathways play a prominent role in glial transformation. In addition, deregulation of polypeptide growth factors acting via receptor tyrosine kinases (RTKs) and of intracellular signals, including the lipid phosphatase PTEN, that regulate cellular responses to RTKs plays a critical role in gliomagenesis. In addition to the identification of the signaling proteins targeted in glial transformation, the cell-of-origin of astrocytomas has been investigated. Genetic modeling of astrocytomas in mice suggests that neuroepithelial precursor cells represent preferred cellular substrates of gliomas or that either astrocytes or precursor cells constitute potential cells-of-origin of astrocytomas. During normal brain development, neuroepithelial precursor cells, including neural stem cells, differentiate into astrocytes. As the mechanisms that control gliogenesis during normal brain development become better understood, it will be important to determine if deregulation of these mechanisms might contribute to the pathogenesis of astrocytomas. The elucidation of the molecular underpinnings of astrocytomas holds the promise of improved treatment options for patients with these devastating brain tumors.
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PMID:Signaling pathways regulating gliomagenesis. 1255 76

We present a new cell line, EN, established from an invasive endometrioid adenocarcinoma of the uterine corpus in 50-year-old patient. The cells show rapid growth in culture with a doubling time of 24.4 hours and high migration activity. Monolayer-cultured cells were polygonal in shape and showed a tendency to pile up without contact inhibition. Subcutaneous transplantation of the EN cells into nude mice formed solid tumors that were histologically diagnosed as adenocarcinoma, whereas no metastasis was observed. Cultured EN cells produced tissue polypeptide antigen. Genetic and molecular analyses revealed high telomerase activity and estrogen receptor beta but not alpha expression. Using the polymerase chain reaction-single strand conformation polymorphism technique, we have screened EN cells for TP53 mutation in exons 5-8. A mobility shift was observed in this cell line in exon 8. A nucleotide insertion (CGT-->CAGT) was detected at codon 273, which resulted in a creation of a stop codon at codon 308. This cell line thus appears to represent the development of a more malignant clone with divergent receptor function and growth behavior, and provides us with an interesting new tool for the study of tumorigenesis in the human endometrium.
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PMID:Establishment of a new human cell line (EN) with TP53 mutation derived from endometrial carcinoma. 1258 94

In recent years, numerous serum and cell/tissue-based markers have been described for colorectal cancer (CRC). The aim of this article was to provide guidelines for the routine clinical use of some of these markers. Lack of sensitivity and specificity preclude the use of any available serum markers such as carcinoembryonic antigen (CEA), CA 19-9, CA 242, CA 72-4, tissue polypeptide antigen (TPA) or tissue polypeptide-specific antigen (TPS) for the early detection of CRC. However, preoperative measurement of CEA is desirable as this may give independent prognostic information, help with surgical management and provide a baseline level for subsequent determinations. For patients with stage 2 (Dukes' B) and 3 (Dukes' C) disease who may be candidates for liver resection, CEA levels should be measured every 2-3 months for at least 3 years after diagnosis. For monitoring treatment of advanced disease, CEA should also be tested every 2-3 months. Insufficient evidence is presently available to recommend the routine use of other serum markers for monitoring purposes. Similarly, the new cell and tissue-based markers (e.g, ras, P53) cannot yet be recommended for routine clinical use.
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PMID:Clinical utility of biochemical markers in colorectal cancer: European Group on Tumour Markers (EGTM) guidelines. 1265 Nov 95

The mismatch repair (MMR) gene hMLH1 is mutated in approximately 50% of hereditary non-polyposis colon cancers and transcriptionally silenced in approximately 25% of sporadic tumours of the right colon. Cells lacking hMLH1 display microsatellite instability and resistance to killing by methylating agents. In an attempt to study the phenotypic effects of hMLH1 downregulation in greater detail, we designed an isogenic system, in which hMLH1 expression is regulated by doxycycline. We now report that human embryonic kidney 293T cells expressing high amounts of hMLH1 were MMR-proficient and arrested at the G(2)/M cell cycle checkpoint following treatment with the DNA methylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), while cells not expressing hMLH1 displayed a MMR defect and failed to arrest upon MNNG treatment. Interestingly, MMR proficiency was restored even at low hMLH1 concentrations, while checkpoint activation required a full complement of hMLH1. In the MMR-proficient cells, activation of the MNNG-induced G(2)/M checkpoint was accompanied by phosphorylation of p53, but the cell death pathway was p53 independent, as the latter polypeptide is functionally inactivated in these cells by SV40 large T antigen.
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PMID:Methylation-induced G(2)/M arrest requires a full complement of the mismatch repair protein hMLH1. 1272 90

The migrating position of green fluorescent protein (GFP)-fused polypeptide varied on an SDS/urea gel by a single amino acid change in the fused polypeptide segment. An easy detection method for a single amino acid change based on this observation was called "GFP-display." Using various target polypeptides, staphylococcal protein A (SpA), Ras, p53, and human beta3 adrenergic receptor (AR), and their mobility-shift patterns resulting from the single amino acid changes, several important properties of GFP-display were revealed as follows: (i). since the binding of dodecyl sulfate ions to acidic or hydrophilic amino acids is weaker than that to basic or hydrophobic amino acids, the ions bound weakly to the fused polypeptide segment are forced to come off by high concentrations of urea prior to the ions bound strongly, resulting in the mobility shift, (ii). the mobility shift is estimated to a certain extent using a new parameter called the "GD value" calculated from the isoelectric point, hydrophilicity, and number of fused amino acids, and (iii). the fluorescence intensity of GFP-fused polypeptide tends to increase with the average hydrophilicity of the fused polypeptide segment. GFP-display will be a helpful technique for many kinds of gene or protein studies related to amino acid substitutions such as the random mutagenesis in a gene of interest.
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PMID:General properties of GFP-display, an electrophoretic analysis for single amino acid changes in target polypeptides. 1272 7

p73 is one of the p53 family members which are transcription factors involved in the regulation of cell proliferation, apoptosis, and differentiation. In this study, we cloned the p73 cDNA from zebrafish ovary RNA. The consensus open reading frame (1923bp) encodes a polypeptide of 640 amino acids which shares 70-95% identity to the p73 of other vertebrates. Expression of zebrafish p73 mRNA is restricted to tissues such as skin, fin, brain, ovary, and testis, in contrast to the ubiquitous expression of zebrafish p53 and p63. During embryonic development, p73 transcripts are detected from the zygote period to the early larva stage. Whole-mount in situ hybridization reveals that p73 expression is in the brain, including olfactory bulbs, telencephalon, and hypothalamus, as well as in the pharyngeal arches and the nose. Moreover, p73 protein is found in the ovary and testis sections by immunohistochemical staining.
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PMID:Cloning and developmental expression of p73 cDNA in zebrafish. 1285 70

Activation of a temperature-sensitive form of p53 in murine erythroleukaemia cells results in a rapid impairment of protein synthesis that precedes inhibition of cell proliferation and loss of cell viability by several hours. The inhibition of translation is associated with specific cleavages of polypeptide chain initiation factors eIF4GI and eIF4B, a phenomenon previously observed in cells induced to undergo apoptosis in response to other stimuli. Although caspase activity is enhanced in the cells in which p53 is activated, both the effects on translation and the cleavages of the initiation factors are completely resistant to inhibition of caspase activity. Moreover, exposure of the cells to a combination of the caspase inhibitor z-VAD.FMK and the survival factor erythropoietin prevents p53-induced cell death but does not reverse the inhibition of protein synthesis. We conclude that the p53-regulated cleavages of eIF4GI and eIF4B, as well as the overall inhibition of protein synthesis, are caspase-independent events that can be dissociated from the induction of apoptosis per se.
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PMID:p53-induced inhibition of protein synthesis is independent of apoptosis. 1286 87

We present a new cell line, EJ established from an invasive endometrioid adenocarcinoma of the uterine corpus in a 56-year-old patient. The cells show rapid growth in culture with a doubling time of 16 h and high migration activity. Monolayer-cultured cells were polygonal in shape showing a tendency to pile up without contact inhibition. Subcutaneous transplantation of the EJ cells into nude mice formed solid tumors that were histologically diagnosed as adenocarcinoma, whereas no metastasis was observed. Cultured EJ cells produced tissue polypeptide antigen (IPA). Genetic and molecular analyses revealed high telomerase activity but not estrogen receptor alpha expression. Using the DNA sequencing technique, we have screened EJ cells for p53 mutation in exon 5 to 8 but no mutation of p53 was observed. This cell line appears to represent the development of a more malignant clone with divergent receptor function and growth behavior, and provides us with an interesting new tool for the study of tumorigenesis in the human endometrium.
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PMID:Establishment and characterization of a new human cell line (EJ) derived from endometrial carcinoma. 1288 55

Gankyrin is a 25-kDa hepatocellular carcinoma-associated protein that mediates protein-protein interactions in cell cycle control and protein degradation. It has been reported to form complexes with cyclin-dependent kinase 4, retinoblastoma protein, the S6b ATPase subunit of the 19 S regulator of the 26 S proteasome, and Mdm2, an E3 ubiquitin ligase involved in p53 degradation. It is the first protein described to bind both to the 26 S proteasome and to proteins in other complexes containing cyclin-dependent kinase(s) and p53 ubiquitylating activities, thus providing a mechanism for delivering cell cycle regulating machinery and ubiquitylated substrates to the proteasome for degradation. Gankyrin contains a 33-residue motif known as the ankyrin repeat that occurs five and a half to six times in the sequence. As a step toward understanding gankyrin interactions with its protein partners we have determined its three-dimensional crystal structure to 2.0-A resolution. It reveals that the entire 226-residue gankyrin polypeptide folds into seven ankyrin repeat elements. The ankyrin repeats, consisting of an antiparallel beta-hairpin followed by a perpendicularly oriented helix-loop-helix, pack side-by-side, creating an extended curved structure with a groove running across the long concave surface. Comparison with the structures of other ankyrin repeat proteins suggests that interactions with partner proteins are mediated by residues situated on this concave surface.
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PMID:The crystal structure of gankyrin, an oncoprotein found in complexes with cyclin-dependent kinase 4, a 19 S proteasomal ATPase regulator, and the tumor suppressors Rb and p53. 1457 99


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