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)

Ku is a heterodimeric protein composed of approximately 70- and approximately 80-kDa subunits (Ku70 and Ku80) originally identified as an autoantigen recognized by the sera of patients with autoimmune diseases. Ku has high binding affinity for DNA ends and that is why originally it was known as a DNA end binding protein, but now it is known to also bind the DNA structure at nicks, gaps, hairpins, as well as the ends of telomeres. It has been reported also to bind with sequence specificity to DNA and with weak affinity to RNA. Ku is an abundant nuclear protein and is present in vertebrates, insects, yeast, and worms. Ku contains ssDNA-dependent ATPase and ATP-dependent DNA helicase activities. It is the regulatory subunit of the DNA-dependent protein kinase that phosphorylates many proteins, including SV-40 large T antigen, p53, RNA-polymerase II, RP-A, topoisomerases, hsp90, and many transcription factors such as c-Jun, c-Fos, oct-1, sp-1, c-Myc, TFIID, and many more. It seems to be a multifunctional protein that has been implicated to be involved directly or indirectly in many important cellular metabolic processes such as DNA double-strand break repair, V(D)J recombination of immunoglobulins and T-cell receptor genes, immunoglobulin isotype switching, DNA replication, transcription regulation, regulation of heat shock-induced responses, regulation of the precise structure of telomeric termini, and it also plays a novel role in G2 and M phases of the cell cycle. The mechanism underlying the regulation of all the diverse functions of Ku is still obscure.
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PMID:Ku autoantigen: a multifunctional DNA-binding protein. 1075 64

The yeast Sir2 protein mediates chromatin silencing through an intrinsic NAD-dependent histone deacetylase activity. Sir2 is a conserved protein and was recently shown to regulate lifespan extension both in budding yeast and worms. Here, we show that SIRT1, the human Sir2 homolog, is recruited to the promyelocytic leukemia protein (PML) nuclear bodies of mammalian cells upon overexpression of either PML or oncogenic Ras (Ha-rasV12). SIRT1 binds and deacetylates p53, a component of PML nuclear bodies, and it can repress p53-mediated transactivation. Moreover, we show that SIRT1 and p53 co-localize in nuclear bodies upon PML upregulation. When overexpressed in primary mouse embryo fibroblasts (MEFs), SIRT1 antagonizes PML-induced acetylation of p53 and rescues PML-mediated premature cellular senescence. Taken together, our data establish the SIRT1 deacetylase as a novel negative regulator of p53 function capable of modulating cellular senescence.
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PMID:Human SIR2 deacetylates p53 and antagonizes PML/p53-induced cellular senescence. 1200 91

Infection by the intestinal nematode Nippostrongylus brasiliensis induces acceleration of apoptosis in the small intestinal villus epithelial cells in vivo. In the present study, we examined whether worm extract or excretory-secretory product induces apoptosis in the rat intestinal epithelial cell line IEC-6 in vitro. In the presence of worm extract or excretory-secretory product (> or =6 microg/ml), IEC-6 cell growth was significantly suppressed, and there was a concomitant increase in the number of detached cells in culture dishes. Detached cells showed nuclear fragmentation, activation of caspase-3, and specific cleavage of poly(ADP-ribose) polymerase, suggesting that apoptosis was induced in these cells. Semiquantitative reverse transcription-PCR showed that expression of Fas (CD95) mRNA was up-regulated as early as 6 h after addition of excretory-secretory product, while Fas ligand expression and p53 expression were not up-regulated. Fluorescence-activated cell sorter analyses revealed a significant increase in Fas expression and a slight increase in FasL expression in IEC-6 cells cultured in the presence of excretory-secretory product, while control IEC-6 cells expressed neither Fas or FasL. These results indicated that N. brasiliensis worms produce and secrete biologically active molecules that trigger apoptosis in intestinal epithelial cells together with up-regulation of Fas expression, although the mechanism of induction of apoptosis remains to be elucidated.
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PMID:Up-regulation of Fas (CD95) and induction of apoptosis in intestinal epithelial cells by nematode-derived molecules. 1211 5

According to the author's theory of gene silencing, the key process in aging involves reduced expression of a number of genes. Silencing of genes has a complex mechanism, which involves methylation of DNA, histone modification and chromatin remodeling. In addition to deacetylation of the histones and methylation of DNA, recently described RNAi mechanism could initiate formation of silenced chromatin. Hypermethylation of the promoter will silence the gene. Genome-wide hypomethylation will induce genomic instability, amplification of oncogenes and also silencing of the genes through RNAi mechanism. Studies by different groups, conducted in yeast, worms, flies and mice, confirmed substantial changes in gene expression in aging. Among them, the most important was silencing of tumor suppressors and other genes involved in the control of cell cycle, apoptosis, detoxification, and cholesterol metabolism. There was also increased expression of the smaller group of oncogenes and other genes which are associated with typical diseases of old age. Caloric restriction normalizes expression of a substantial percentage of these genes. Animal studies confirmed importance of caloric restriction, which decreases signaling through the IGF-1/AKT pathway and expression of gene p53. These studies, however, cannot be directly applied to human aging. It is proposed that age management therapy should attempt to normalize gene expression in the older population to the level typical for young adults. This would require activation of silenced genes and normalization of overexpressed genes. Caloric restriction and exercise are helpful in decreasing the activity of important oncogenes and activation of silenced tumor suppressors, and may have a positive impact, not only on aging, but also on prevention of cancer. Dietary supplements containing phytochemicals should normalize increased expression of oncogenes. Examples are: genistein and EGCG, which effect signaling through the IGF-1/AKT pathway and resveratrol and limonen, which do so through the RAS pathway. A group of amino acid derivatives and organic acids of animal and human origin should activate silenced tumor suppressor genes (Aminocare A10, Aminocare Extra). Among them 3-phenylacetylamino-2, 6-piperidinedione intercalates specifically with DNA and protects sequences of tumor suppressor genes, which are vulnerable to the effects of carcinogens. Phenylacetate activates p53 and p21 through inhibition of methyltransferase and farnesylation of the RAS protein. Phenylbutyrate activates tumor suppressor genes through inhibition of histone deacetylation. Phenylacetylglutamine decreases genomic instability and expression of oncogenes and promotes apoptosis. The application of DNA microarray techniques to human studies should provide more information about differences in gene expression in different age groups and help design more effective age management regimens.
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PMID:Aging: gene silencing or gene activation? 1553 42

Sir2 is a NAD+-dependent protein deacetylase that extends lifespan in yeast and worms. This study examines seven human proteins homologous to Sir2 (SIRT1 through SIRT7) for cellular localization, expression profiles, protein deacetylation activity, and effects on human cell lifespan. We found that: 1) three nuclear SIRT proteins (SIRT1, SIRT6, and SIRT7) show different subnuclear localizations: SIRT6 and SIRT7 are associated with heterochromatic regions and nucleoli, respectively, where yeast Sir2 functions; 2) SIRT3, SIRT4, and SIRT5 are localized in mitochondria, an organelle that links aging and energy metabolism; 3) cellular p53 is a major in vivo substrate of SIRT1 deacetylase, but not the other six SIRT proteins; 4) SIRT1, but not the other two nuclear SIRT proteins, shows an in vitro deacetylase activity on histone H4 and p53 peptides; and 5) overexpression of any one of the seven SIRT proteins does not extend cellular replicative lifespan in normal human fibroblasts or prostate epithelial cells. This study supports the notion that multiple human SIRT proteins have evolutionarily conserved and nonconserved functions at different cellular locations and reveals that the lifespan of normal human cells, in contrast to that of lower eukaryotes, cannot be manipulated by increased expression of a single SIRT protein.
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PMID:Evolutionarily conserved and nonconserved cellular localizations and functions of human SIRT proteins. 1607 81

Unconventional prefoldin RPB5 interactor (URI), an evolutionary conserved member of the prefoldin family of molecular chaperones, plays a central role in the regulation of nutrient-sensitive, TOR (target-of-rapamycin)-dependent gene expression programs in yeast. Mammalian URI has been shown to associate with key components of the transcriptional machinery, including RPB5, a shared subunit of all three RNA polymerases, the ATPases TIP48 and TIP49, which are present in various chromatin remodeling complexes, and human PAF1 and parafibromin, which are components of a transcription elongation complex. Here, we provide the first functional characterization of a URI-1 homolog in a multicellular organism and show that the C. elegans gene uri-1 is essential for germ cell proliferation. URI-1-deficient cells exhibit cell cycle arrest and display DNA breaks as evidenced by TUNEL staining and the appearance of HUS-1::GFP foci formation. In addition, uri-1(lf) mutants and uri-1(RNAi) worms show a p53-dependent increase in germline apoptosis. Our findings indicate that URI-1 has an important function in the mitotic and meiotic cell cycles. Furthermore, they imply that URI-1 participates in a pathway(s) that is associated with the suppression of endogenous genotoxic DNA damage and highlight a role for URI-1 in the control of genome integrity.
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PMID:URI-1 is required for DNA stability in C. elegans. 1643 22

Over the past 10 years the signal transduction networks for p53, IGF-1-AKT, and TOR pathways have been assembled in worms, flies, and mammals, and their functions elucidated. In the past 1-2 years a number of genes and their proteins have been identified that permit extensive communication and coordination between these pathways. These three pathways are involved in sensing and integrating signals arising from nutrient and growth factor availability, signals from sensory and sexual organs, and intrinsic and extrinsic stress signals. In turn these pathways regulate cell growth, proliferation, and death. These networks are central to our understanding of a variety of physiological and pathological conditions, including cancer, diabetes, and longevity.
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PMID:Coordination and communication between the p53 and IGF-1-AKT-TOR signal transduction pathways. 1645 1

The discovery that the p53 family consists of three members (p53, p63 and p73) in vertebrates and of a single homolog in invertebrates has raised the challenge of understanding the functions of the ancestor and how they have evolved and differentiated within the duplicated genes in vertebrates. Here, we report that the fatty acid synthase (FAS) gene, encoding for a key enzyme involved in the biogenesis of membrane lipids in rapidly proliferating cells, is a conserved target of the p53 family throughout the evolution. We show that CEP-1, the C. elegans p53 homolog, is able to bind the two p53 family responsive elements (REs) identified in the worm fasn-1 gene. Moreover, we demonstrate that fasn-1 expression is modulated by CEP-1 in vivo, by comparing wild-type and CEP-1 knockout worms. In human, luciferase and chromatin immunoprecipitation assays demonstrate that TAp73alpha and DeltaNp63alpha, but not p53, TAp73beta and TAp63alpha bind the two p53 REs of the human FASN gene. We show that the ectopic expression of TAp73alpha and DeltaNp63alpha leads to an increase of FASN mRNA levels, while their silencing produces a decrease of FASN expression. Furthermore, we present data showing a correlation between DeltaNp63alpha and FASN expression in cellular proliferation. Of relevant importance is that fasn-1 is the first CEP-1 direct target gene identified so far in C. elegans and our results suggest a new CEP-1 role in cellular proliferation and development, besides the one already described in apoptosis of germ cells. These data confirm the hypothesis that the ancestral functions of the single invertebrate gene may have been spread out among the three vertebrate members, each of them have acquired specific role in cell cycle regulation.
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PMID:The fatty acid synthase gene is a conserved p53 family target from worm to human. 1658 25

Cyromazine is an effective insecticide used to control dipteran insects. Its precise mode of action is yet to be determined, although it has been suggested that it interferes with the hormone system, sclerotization of the cuticle, or nucleic acid metabolism. To understand the way in which cyromazine acts, we have positionally cloned a cyromazine resistance gene from Drosophila melanogaster. Six cyromazine resistance alleles had previously been generated by ethyl methanasulphonate treatment. Two of these failed to complement each other and here we identify them as having independent non-sense mutations in CG32743, which is an ortholog of Smg1 of worms and mammals and encodes a phosphatidylinositol kinase-like kinase (PIKK). RNAi experiments confirm that cyromazine resistance can be achieved by knocking down CG32743. These are the first cyromazine resistant mutations identified at the nucleotide level. In mammals Smg1 phosphorylates P53 in response to DNA damage. This finding supports the hypothesis that cyromazine interferes with nucleic acid metabolism.
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PMID:Positional cloning of a cyromazine resistance gene in Drosophila melanogaster. 1664 Jul 28

The toxicity of cadmium, lead, chromium, and arsenite on Caenorhabditis elegans was investigated to identify sensitive biomarkers for environmental monitoring and risk assessment. Effects of these metals on stress-related gene expression, growth, reproduction, and mortality of C. elegans were investigated under laboratory conditions. The possibility of using C. elegans as a biosensor for environmental toxicity monitoring was also tested using a green fluorescent protein transgenic nematode. The 24-h median lethal concentrations of cadmium, lead, chromium, and arsenite in C. elegans were 846, 34, 115, and 92 mg/L, respectively. Cadmium exposure led to an increase in the expression of most of the genes tested. The degree of increase was more than threefold compared to control in heat shock protein 16.2, heat shock protein 70, metallothionein 2, cytochrome P450 family protein 35A2, glutathione-S-transferase 4, superoxide dismutase 1, catalase 2, C. elegans p53-like protein 1, and apoptosis enhancer 1 genes. The lead-, chromium-, and arsenite-exposed nematode, on the other hand, showed little change in gene expression. Alterations in growth and reproduction were observed in cadmium- and chromium-exposed worms. To consider a transgenic nematode as a biosensor for toxicity monitoring, the responses of stress-related gene promoters need to be tested with a variety of metals. The overall results suggest that cadmium exhibits a high level of tolerance compared to the other metals tested. Use of the responses of stress-related gene expression therefore has considerable potential as a sensitive biomarker for the diagnosis of cadmium contamination, and C. elegans seems to be a good biological model for this approach.
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PMID:Assessment of stress-related gene expression in the heavy metal-exposed nematode Caenorhabditis elegans: a potential biomarker for metal-induced toxicity monitoring and environmental risk assessment. 1708 18


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