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)

Histone deacetylase 2 (HDAC2) is one of the histone-modifying enzymes that regulate gene expression by remodeling chromatin structure. Along with HDAC1, HDAC2 is found in the Sin3 and NuRD multiprotein complexes, which are recruited to promoters by DNA-binding proteins. In this study, we show that the majority of HDAC2 in human breast cancer cells is not phosphorylated. However, the minor population of HDAC2, preferentially cross-linked to DNA by cisplatin, is mono-, di-, or tri-phosphorylated. Furthermore, HDAC2 phosphorylation is required for formation of Sin3 and NuRD complexes and recruitment to promoters by transcription factors including p53, Rb, YY1, NF-kappaB, Sp1, and Sp3. Unmodified HDAC2 requires linker DNA to associate with chromatin but is not cross-linked to DNA by formaldehyde. We provide evidence that unmodified HDAC2 is associated with the coding region of transcribed genes, whereas phosphorylated HDAC2 is primarily recruited to promoters.
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PMID:Differential distribution of unmodified and phosphorylated histone deacetylase 2 in chromatin. 1782 54

Inhibitors for the classical protein deacetylase enzymes have been actively pursued to develop the next generation of cancer therapy. Developing a novel convenient assay platform for the classical enzyme-catalyzed reactions could thus facilitate the drug discovery process. Based on our previous studies demonstrating the functional mimicry of N(epsilon)-thioacetyl-lysine for N(epsilon)-acetyl-lysine in the reaction catalyzed by the classical enzyme histone deacetylase 8 (HDAC8) on a peptide template derived from the C terminus of the human p53 tumor suppressor protein, we have developed a spectrophotometric HDAC8 assay via quantifying thioacetate produced from the enzymatic dethioacetylation with Ellman's reagent 5,5'-dithiobis(2-nitrobenzoate). We further demonstrated that this novel assay was selective for HDAC8 versus HDAC1 and 2 and for other classical protein deacetylase enzymes present in the HeLa nuclear extracts, thus making it potentially suitable not only for screening HDAC8-selective inhibitors but also for selectively assessing HDAC8 activity under (patho)physiological conditions.
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PMID:A spectrophotometric assay for histone deacetylase 8. 1792 May 54

ICBP90/UHRF1, which is overexpressed in cancer cells and is down-regulated by p53, possesses a methylated CpG binding affinity and binds to the methylated promoters of tumor suppressor genes in cancer cells with HDAC1 and DNMT1, suggesting suppression of these genes and maintenance of methylation status which leads to carcinogenesis. Recently, it was reported that the human homolog of Np95 is different from ICBP90 but not from UHRF1. Because UHRF1 is the gene symbol of ICBP90, the claim is a little confusing; that is, UHRF1 and ICBP90 are identical. Because the previously published genomic structure of the ICBP90 gene needed to be revised and the registered ICBP90 sequence (AF129507) contains two rare polymorphisms or sequence errors, we think that confusion could occur. Here we show the revised ICBP90 gene structure and 366 polymorphisms in this gene. Our conclusion is that the human homolog of Np95 is ICBP90, whose gene symbol is UHRF1.
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PMID:A concern regarding the current confusion with the human homolog of mouse Np95, ICBP90/UHRF1. 1822 Apr 74

Pirh2 is a RING finger type ubiquitin ligase which ubiquitylates various proteins including p53, p27(Kip1), HDAC1, and epsilon-COP. In this study, we identified signal recognition particle receptor beta subunit (SRbeta), an integral membrane protein of the endoplasmic reticulum (ER), as a novel Pirh2-interacting protein by yeast two-hybrid screening. We confirmed that Pirh2 interacted with SRbeta in mammalian cells. An immunofluorescent staining revealed that Pirh2 colocalized with SRbeta in the ER. Pirh2 poly-ubiquitylated SRbeta in an intact RING finger domain-dependent manner in vivo and in vitro. Unexpectedly, different from other Pirh2 substrates, neither overexpression of Pirh2 nor depletion of cellular Pirh2 affected SRbeta protein stability. Pirh2 preferentially utilized lysine residues 6 and 29 of the ubiquitin to mediate the formation of polyubiquitin chains on SRbeta. These results suggest that Pirh2 may regulate SRbeta function by mediating poly-ubiquitylation of SRbeta without affecting the stability of SRbeta protein per se.
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PMID:Pirh2 interacts with and ubiquitylates signal recognition particle receptor beta subunit. 1834 99

Statins are 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors broadly used for the control of hypercholesterolemia. Recently, they are reported to have beneficial effects on certain cancers. In this study, we show that statins inhibited the histone deacetylase (HDAC) activity and increased the accumulation of acetylated histone-H3 and the expression of p21(WAF/CIP) in human cancer cells. Computational modeling showed the direct interaction of the carboxylic acid moiety of statins with the catalytic site of HDAC2. In the subsequent enzymatic assay, it was shown that lovastatin inhibited HDAC2 activity competitively with a K(i) value of 31.6 micromol/L. Sp1 but not p53 sites were found to be the statins-responsive element shown by p21 luciferase-promoter assays. DNA affinity protein binding assay and chromatin immunoprecipitation assay showed the dissociation of HDAC1/2 and association of CBP, leading to the histone-H3 acetylation on the Sp1 sites of p21 promoter. In vitro cell proliferation and in vivo tumor growth were both inhibited by statins. These results suggest a novel mechanism for statins through abrogation of the HDAC activity and promoter histone-H3 acetylation to regulate p21 expression. Therefore, statins might serve as novel HDAC inhibitors for cancer therapy and chemoprevention.
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PMID:Statins increase p21 through inhibition of histone deacetylase activity and release of promoter-associated HDAC1/2. 1838 45

Many studies aim at improving therapeutic efficacy by combining strategies with oxidative stress-inducing drugs and histone deacetylase (HDAC) inhibitors in colorectal cancer. As p53 and p21(WAF1) are essential in oxidative stress-induced DNA damage, we investigated epigenetic regulation of p21(WAF1) promoter. Firstly, HCT116 p53(+)/(+) and p53(-)/(-) colorectal cancer cells were treated with H(2)O(2) for 6 hrs and 24 hrs (early/late response). Chromatin immunoprecipitation revealed transcriptional transactivation of p21(WAF1) in HCT116 p53(+)/(+) cells as shown by increased binding of p53 and acetylated H4 around two p21(WAF1) promoter sites, the responsible element (RE) and the Sp1 site, while both proteins bound preferentially on the RE. Interestingly, H3 was not involved, suggesting H4-specific transactivation of the p21(WAF1) promoter. H(2)O(2) addition resulted in G(2)/M arrest of both HCT116 cell lines without significant cell death. To investigate whether a HDAC inhibitor strengthens G(2)/M arrest, we pretreated cells with Trichostatin A (TSA). In HCT116 p53(+)/(+) cells, we found (i) remarkably increased acetylated H4 around both p21(WAF1) promoter regions, especially at the Sp1 site; (ii) increased acetylation of p53 at lysines 320 and 382;(iii) displacement of HDAC1 from the Sp1 site, thus inhibiting its repression effect and increasing p53 binding.p53 seems to trigger H4-acetylation around the p21(WAF1) promoter because there was nearly no H4 acetylation in HCT116 p53(-)/(-) cells. For the first time we show that there is a time-dependent TSA mode of action with increased p53-dependent histone H4 acetylation at the p21(WAF1) promoter in early response, and decreased acetylation in late response. Reduced p53-triggered transactivation of p21(WAF1) in late response allows cells to re-enter cell cycle, and TSA causes p53 to simultaneously induce apoptosis.
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PMID:Trichostatin A causes p53 to switch oxidative-damaged colorectal cancer cells from cell cycle arrest into apoptosis. 1841

MDM2 is the most important negative regulator of tumor suppressor p53. Both RING finger domain and acidic domain of MDM2 contribute to the ubiquitination of p53. The crosstalk between ubiquitination and acetylation of p53 prompts us to examine whether acidic domain is essential for MDM2 to regulate the acetylation of p53. We find that the acidic domain of MDM2 is necessary to inhibit p300-mediated acetylation of p53 as well as to mediate the deacetylation of p53. Our results indicate that acidic domain of MDM2 provides essential information for acetyltransferase p300 and deacetylase HDAC1 and is indispensable for MDM2 to negatively regulate the acetylation of p53.
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PMID:Acidic domain is indispensable for MDM2 to negatively regulate the acetylation of p53. 1863 52

Herein, we show that both exogenously transfected and endogenously activated p53 repress promoter activity and expression of PDGFRB. p53 binds the proximal promoter containing the CCAAT motif as examined by EMSA and chromatin immunoprecipitation. However, gradual induction of p53 in tet-onSAOS2 cells resulted in a transient increase of the PDGFRB-promoter activity and its expression. As binding of p53 to the promoter increased, previously bound p73, DeltaNp73, c-Myc, HDAC1 and HDAC4 were dismissed from the repressed promoter, and p300 was recruited. The transient increase of the promoter activity was therefore induced by the release of the p73, Myc and HDACs, previously shown to act as repressors to this promoter. Along with further increase of p53, p300 was replaced by HDAC1 and HDAC4, resulting in decreased PDGFRB expression. For the repression, acetylation of the C-terminal lysines of p53 is important, and both acetyl-K373p53 and methyl-K370p53 became bound to the promoter. The acetyl-K373p53 was accumulated in the nucleus and colocalized with promyelocytic leukemia protein. Mitomycin treatment of MEF induced similar epigenetic modification of p53 and its binding to the promoter chromatin. Addition of a PDGFR tyrosine-kinase inhibitor to p53-inducing tet-onSAOS2 increased the number of apoptotic cells. These results suggest that p53 represses the PDGFRB promoter, facilitating the p53-induced apoptosis, whereas tumor cells with p53 mutation or a high level of DeltaNp73 or Myc could become refractory to the regulation.
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PMID:Kinetics of repression by modified p53 on the PDGF beta-receptor promoter. 1869 3

The mammalian AP-endonuclease (APE1/Ref-1) plays a central role in the repair of oxidized and alkylated bases in mammalian genomes via the base excision repair (BER) pathway. However, APE1, unlike its E. coli prototype Xth, has two unique and apparently distinct transcriptional regulatory activities. APE1 functions as a redox effector factor (Ref-1) for several transcription factors including AP-1, HIF1-alpha, and p53. APE1 was also identified as a direct trans-acting factor for repressing human parathyroid hormone (PTH) and renin genes by binding to the negative calcium-response element (nCaRE) in their promoters. We have characterized APE1's post-translational modification, namely, acetylation which modulates its transcriptional regulatory function. Furthermore, stable interaction of APE1 with several other trans-acting factors including HIF-1alpha, STAT3, YB-1, HDAC1, and CBP/p300 and formation of distinct trans-acting complexes support APE1's direct regulatory function for diverse genes. Multiple functions of mammalian APE1, both in DNA repair and gene regulation, warrant extensive analysis of its own regulation and dissection of the mechanisms. In this review, we have discussed APE1's own regulation and its role as a transcriptional coactivator or corepressor by both redox-dependent and redox-independent (acetylation-mediated) mechanisms, and explore the potential utility of targeting these functions for enhancing drug sensitivity of cancer cells.
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PMID:Transcriptional regulatory functions of mammalian AP-endonuclease (APE1/Ref-1), an essential multifunctional protein. 1871 44

Histone deacetylases (HDACs) are subdivided into three classes--HDAC I, HDAC II, and Sir2. Sirt proteins are mammalian members of the Sir2 family of NAD+ (nicotinamide adenine dinucleotide)-dependent protein deacetylases. The balance between acetylation and deacetylation of histone and non-histone proteins, regulated by protein acetyltransferases and deacetylases, affects the expression of genes involved in a variety of cellular processes. In addition, HDAC1 is acetylated and regulated by p300, a transcriptional co-activator with protein acetyltransferase activity, suggesting that protein acetyltransferases and deacetylases they control the activities of each other. Although the regulation of HDAC1 by p300 is well characterized, the relationship between Sir2 homologs and p300 is not understood. Here, we report that p300 interacts with Sirt2, a member of the Sir2 family, and triggers the acetylation and subsequent down-regulation of the deacetylation activity of Sirt2, and that the acetylation of Sirt2 by p300 relieves the inhibitory effect of Sirt2 on the transcriptional activity of p53. These observations demonstrate that p300 can inactivate Sirt2 by acetylation and that p300 may regulate the activity of p53 indirectly through Sirt2 in addition to its direct modification of p53.
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PMID:Acetylation of Sirt2 by p300 attenuates its deacetylase activity. 1872 53


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