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 p53-regulated GADD45 gene is one of the important players in cellular response to DNA damage, and probably involved in the control of cell cycle checkpoint, apoptosis and DNA repair. There are both the p53-dependent and -independent pathways that regulate GADD45 induction. Following ionizing radiation, induction of the GADD45 gene is regulated by p53 through the p53-binding motif located in the third intron of the GADD45 gene. In contrast, GADD45 induction by methyl methanesulfonate (MMS), UV radiation (UV), and medium starvation is independent of p53 status although p53 may contribute to these responses. However, the regulatory elements that control the p53-independent induction of GADD45 remain uncertain. In this report, we have performed detailed analyses to characterize the responsive components that are required for the induction of the GADD45 promoter. We have found that the region between -107 and -62 of the GADD45 promoter is crucial for the induction. Sequence analysis indicates that there are two OCT-1 sites and one CAAT box located in this region. Site-directed mutations of both OCT-1 and CAAT motifs substantially abrogate the induction of the GADD45 promoter by DNA damage. In addition, both Oct-1 protein (binding to OCT-1 site) and NF-YA protein (binding to CAAT box) are induced after cell exposure to DNA damaging agents. Moreover, the Electrophoretic Mobility Shift Assay (EMSA) has demonstrated the direct bindings of Oct-1 and NF-YA proteins to their consensus sequences in the GADD45 promoter. Therefore, these results have presented the novel observation that transcription factors Oct-1 and NF-YA participate in the cellular response to DNA damage and are involved in the regulation of stress-inducible genes.
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PMID:Transcription factors Oct-1 and NF-YA regulate the p53-independent induction of the GADD45 following DNA damage. 1142 Jun 80

The biological functions of the tumor suppressor, ING1, have been studied extensively in the last 5 years since it was cloned. It shares many biological functions with those of p53 and has been reported to mediate growth arrest, senescence, apoptosis, anchorage-dependent growth, and chemosensitivity. Some of these functions, such as cell cycle arrest and apoptosis, have been shown to be dependent on the activity of both ING1 and p53 proteins. In this study, we report that p33(ING1) (one of ING1 isoforms) is also involved in the modulation of DNA repair. We found that overexpression of p33(ING1) enhances repair of UV-damaged DNA and that p53 is required for the repair process. Furthermore, binding between ING1 and GADD45 has been detected. These observations suggest that p33(ING1) cooperates with p53 in nucleotide excision repair and that GADD45 may be one of its components.
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PMID:The tumor suppressor candidate p33(ING1) mediates repair of UV-damaged DNA. 1143 27

DNA mismatch repair (MMR) is an efficient system for the detection and repair of mismatched and unpaired bases in DNA. Deficiencies in MMR are commonly found in both hereditary and sporadic colorectal cancers, as well as in cancers of other tissues. Because fluorinated thymidine analogues (which through their actions might generate lesions recognizable by MMR) are widely used in the treatment of colorectal cancer, we investigated the role of MMR in cellular responses to 5-fluorouracil and 5-fluoro-2'-deoxyuridine (FdUrd). Human MLH1(-) and MMR-deficient HCT116 colon cancer cells were 18-fold more resistant to 7.5 microM 5-fluorouracil (continuous treatment) and 17-fold more resistant to 7.5 microM FdUrd in clonogenic survival assays compared with genetically matched, MLH1(+) and MMR-proficient HCT116 3-6 cells. Likewise, murine MLH1(-) and MMR-deficient CT-5 cells were 3-fold more resistant to a 2-h pulse of 10 microM FdUrd than their MLH1(+) and MMR-proficient ME-10 counterparts. Decreased cytotoxicity in MMR-deficient cells after treatment with various methylating agents and other base analogues has been well reported and is believed to reflect a tolerance to DNA damage. Synchronized HCT116 3-6 cells treated with a low dose of FdUrd had a 2-fold greater G(2) cell cycle arrest compared with MMR-deficient HCT116 cells, and asynchronous ME-10 cells demonstrated a 4-fold greater G(2) arrest after FdUrd treatment compared with CT-5 cells. Enhanced G(2) arrest in MMR-proficient cells in response to other agents has been reported and is believed to allow time for DNA repair. G(2) cell cycle arrest as determined by propidium iodide staining was not a result of mitotic arrest, but rather a true G(2) arrest, as indicated by elevated cyclin B1 levels and a lack of staining with mitotic protein monoclonal antibody 2. Additionally, p53 and GADD45 levels were induced in FdUrd-treated HCT116 3-6 cells. DNA double-strand break (DSB) formation was 2-fold higher in MMR-proficient HCT116 3-6 cells after FdUrd treatment, as determined by pulsed-field gel electrophoresis. The formation of DSBs was not the result of enhanced apoptosis in MMR-proficient cells. FdUrd-mediated cytotoxicity was caused by DNA-directed and not RNA-directed effects, because administration of excess thymidine (and not uridine) prevented cytotoxicity, cell cycle arrest, and DSB formation. hMLH1-dependent responses to fluoropyrimidine treatment, which may involve the action of p53 and the formation of DSBs, clearly have clinical relevance for the use of this class of drugs in the treatment of tumors with MMR deficiencies.
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PMID:Role of the hMLH1 DNA mismatch repair protein in fluoropyrimidine-mediated cell death and cell cycle responses. 1143 59

Despite low radiation dose rates, radioimmunotherapy (RIT) has proven particularly effective in the treatment of malignancies, such as lymphoma. Apoptosis has been suggested to be a major mechanism for cell death from continuous low-dose rate radiation from radioimmunotherapy. The goal of this study was to examine Raji lymphoma xenografts for induction of apoptosis and modulation of apoptosis-related gene and protein expression in response to 67Cu-2IT-BAT-Lym-1 RIT. In preclinical and clinical trials, 67Cu-2IT-BAT-Lym-1 has shown an exceptionally long tumor residence time associated with substantial cumulated radiation doses. The Raji model mirrors human lymphomas that have mutant p53 and increased BCL2 expression. Untreated athymic BALB/c nu/nu mice and mice treated with 400 micrograms Lym-1, or 335-500 microCi 67Cu on less than 400 micrograms Lym-1 antibody, were observed for toxicity and response over 84 days. Subgroups of 4-5 mice were sacrificed at 3, 6 and 24 h after therapy so that tumors could be examined for poly(ADP-ribose) polymerase (PARP) and DNA ladder evidence for apoptosis and for BCL2, p53, p21, GADD45, TGF-beta 1 and c-MYC gene and protein expression. Untreated tumors had little evidence of apoptosis and Lym-1 had no effect on apoptosis or gene expression. 67Cu-2IT-BAT-Lym-1 RIT induced an overall response rate of 50% with tolerable toxicity, and 29% of the tumors were cured at cumulated tumor radiation doses of about 1800 cGy. Apoptosis was greatly increased in the RIT treated Raji xenografts as evidenced by cleavage of PARP to the characteristic 85 kD fragment at 3 and 6 h and by the DNA cleavage pattern. BCL2 gene and protein expression were substantially decreased at 3 and 24 h, respectively, after 67Cu-2IT-BAT-Lym-1 RIT despite only modest cumulated radiation doses (56 cGy at 3 h). Evidence for apoptosis preceded tumor regression by 4-6 days. In these therapy-resistant, human lymphoma tumors treated with 67Cu-2IT-BAT-Lym-1, apoptosis was convincingly demonstrated to be a major mechanism for the effectiveness of RIT and occurred by p53-independent mechanisms.
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PMID:Apoptosis-related gene and protein expression in human lymphoma xenografts (Raji) after low dose rate radiation using 67Cu-2IT-BAT-Lym-1 radioimmunotherapy. 1147 86

In vitro two-stage transformation, an important method for the screening of carcinogens, is a valuable approach for the mechanistic study of multi-stage carcinogenesis. However, very little is known about the molecular and cellular mechanisms, particularly in terms of cell cycle control during in vitro two-stage transformation. We improved the in vitro two-stage transformation method using N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as an initiator and cadmium as a promoter, and reconfirmed the promotional effect of cadmium (Fang et al., 2001a). To determine the alterations of cell cycle control in the MNNG-induced initiation stage during transformation, we examined the effects of MNNG on Balb/3T3 A31 cell growth, and determined the alterations of the protein and/or mRNA levels of cyclins B1, D1, E, and G, PCNA, GADD45, p27, and wild-type p53. After 4 hour treatment of MNNG, populations of G2/M phase distribution and apoptotic fraction and the cyclin G mRNA level increased, while the cyclin B1 mRNA level decreased in a concentration-dependent manner. Wild-type p53, p27, and GADD45 protein levels also increased as a function of MNNG concentrations. However, cyclin D1, cyclin E, and PCNA expressions remained unchanged. During the initiation stage, PCNA protein expression decreased on the first day after MNNG-treatment, then increased gradually during the following 6 days, and further increased on the first day after cadmium treatment. Although wild-type p53 and p27 protein expressions also showed temporary retardation on the first day after MNNG-treatment, the expressions increased gradually during the following 6 days, but decreased rapidly by the cadmium treatment. These results indicated that during the initiation stage, MNNG induced G2/M arrest and apoptosis with increased expressions of wild-type p53, p27, and GADD45 proteins; and down-regulated mRNA level of cyclin B1 and up-regulated mRNA level of cyclin G. In addition, although a few of the G2/M-arrested cells proliferated gradually, most cells continued to be suppressed and inactivated by the over-expressions of wild-type p53 and p27 until the cadmium treatment.
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PMID:Cell cycle was disturbed in the MNNG-induced initiation stage during in vitro two-stage transformation of Balb/3T3 cells. 1151 27

The p53-regulated stress-inducible gene GADD45 has been shown to participate in cellular response to DNA damage, including cell cycle checkpoint, apoptosis, and DNA repair. However, the regulation of GADD45 expression is complex and may involve both p53-dependent and -independent pathways. Recent findings have demonstrated that the p53-independent induction of GADD45 is mainly regulated by the transcription factors Oct-1 and NF-YA, which directly bind to their consensus motifs located at the GADD45 promoter region. Here, we report that mitogen-activated protein (MAP) kinases are involved in the induction of the GADD45 promoter after DNA damage. Inhibition of JNK1 and ERK kinase activities either by expression of the dominant negative mutant JNK1 or by treatment with a selective chemical inhibitor of ERK (PD098059) substantially abrogates the UV induction of the GADD45 promoter. In contrast, a p38 kinase inhibitor (SB203580) has little effect on GADD45 induction by UV. In addition, the GADD45 promoter is strongly activated following expression of JNK1; Raf-1, which is an upstream activator of the ERK pathway; or MEK1, an upstream activator of both the ERK and the JNK pathways. Activation of the GADD45 promoter by MAP kinases does not require normal p53 function. Interestingly, the MAP kinase-regulatory effect appears to be mediated via OCT-1 and CAAT motifs since disruption of these sites abrogates activation of the GADD45 promoter by MAP kinases. Therefore, these findings indicate that the MAP kinase pathways are involved in the regulation of the p53-independent induction of the GADD45 promoter, probably via interaction with transcription factors that directly bind to OCT-1 and CAAT motifs.
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PMID:Involvement of the MAP kinase pathways in induction of GADD45 following UV radiation. 1152 40

The function and stability of the tumor suppressor p53 are tightly controlled by the negative regulator mouse double minute 2 (Mdm2), which binds to p53, blocking DNA binding and targeting p53 for proteosome-mediated degradation. Following DNA damage or cellular stress, p53 is phosphorylated within the Mdm2 binding domain on threonine 18 and serine 20. To analyze the roles of these phosphorylation events, residues 18 and 20 were mutated to alanines. Transient transfection into p53-null cells demonstrated that the T18A protein can be expressed stably, but the S20A protein is very unstable, precluding further analysis. When expressed stably at low basal levels in p53-null human fibroblasts or fibrosarcoma cells, the T18A mutant accumulated 5-10-fold less well than wild-type p53 following exposure to UV. Analysis of p53-dependent transcription following UV revealed that the phosphorylation of threonine 18 is required for transactivation of the p21, Hdm2 (the human ortholog of Mdm2), and GADD45 genes. The phosphorylation of serine 33, another early event following DNA damage, is not required for p53 accumulation or p53-dependent transactivation following UV.
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PMID:Regulation of the accumulation and function of p53 by phosphorylation of two residues within the domain that binds to Mdm2. 1170 53

We address here the effects of increasing fluencies of UV-radiation on stability, modifications, activity and HDM2-interactions of endogenous p53 tumor suppressor and on cellular damage response of human diploid fibroblasts. Low amounts of UVB/C-radiation induced a transient cell cycle arrest of the cells which correlated with rapid but transient increase in p53 levels. In contrast, high UV-fluency caused cell apoptosis and a slower but sustained increase in p53. Regulation of p53 target genes was highly dependent on the radiation dose used. Whereas low doses induced p21/Cip1/Waf1 and HDM2, high doses induced only GADD45 and BAX increasing the BAX:BCL-2 ratio. The levels of HDM2, a negative regulator of p53, increased only by the low dose of UVC and p53-HDM2 association was promoted. In the absence of HDM2-induction after the high dose of UV-radiation p53-HDM2-interaction was promoted, but HDM2 failed to downregulate p53. p53 site-specific modifications (Ser15, Ser33, Ser37, Lys382) varied kinetically and were dependent on the fluency of the radiation used. Maximal phosphorylation of p53 on Ser15 and Ser33 correlated with increased levels of HDM2-free p53. The results suggest that regulation of p53 and HDM2 by UV-radiation is highly dose-dependent and contributes to the outcome of the cellular response.
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PMID:UV-radiation induces dose-dependent regulation of p53 response and modulates p53-HDM2 interaction in human fibroblasts. 1170 13

BRCA1, a breast and ovarian cancer susceptibility gene, has been implicated in gene regulation. Previous studies demonstrate that BRCA1 induces GADD45, a p53-regulated and stress-inducible gene that plays an important role in cellular response to DNA damage. However, the mechanism(s) by which BRCA1 regulates GADD45 remains unclear. In this report, we have shown that BRCA1 activation of the GADD45 promoter is mediated through the OCT-1 and CAAT motifs located at the GADD45 promoter region. Site-directed mutations of both OCT-1 and CAAT motifs abrogate induction of the GADD45 promoter by BRCA1. Both OCT-1 and CAAT motifs are able to confer BRCA1 inducibility in a non-related minimal promoter. Physical associations of BRCA1 protein with transcription factors Oct-1 and NF-YA, which directly bind to the OCT-1 and CAAT motifs, are established by biotin-streptavidin pull-down and coimmunoprecipitation assays. Such protein interactions are required for interaction of BRCA1 with the GADD45 promoter because either immunodepletion of Oct-1 and NF-YA proteins or mutations in the OCT-1 and CAAT motifs disrupt BRCA1 binding to the GADD45 promoter. These findings indicate that BRCA1 can up-regulate its targeted genes through protein-protein interactions and provide a novel mechanism by which BRCA1 participates in transcriptional regulation.
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PMID:BRCA1 regulates GADD45 through its interactions with the OCT-1 and CAAT motifs. 1177 30

The aminothiol WR1065, the active metabolite of the cytoprotector amifostine, exerts its antimutagenic effects through free-radical scavenging and other unknown mechanisms. In an earlier report, we showed that WR1065 activates wild-type p53 in MCF-7 cells, leading to p53-dependent arrest in the G(1) phase of the cell cycle. To determine whether WR1065 activates p53 by modulating protein conformation, we analyzed its effects on p53 conformation and activity in the esophageal cancer cell line TE-1. This cell line contains a mutation in codon 272 of p53 (p53(V272M), with methionine instead of a valine), conferring temperature-sensitive properties to the p53 protein. At the nonpermissive temperature (37 degrees C), p53(V272M) adopts the mutant p53 conformation (nonreactive with the antibody PAb1620), does not bind specifically to DNA, and is not activated in response to DNA-damaging treatment. However, treatment with 0.5-4 mM WR1065 partially restored wild-type conformation at 37 degrees C, stimulated DNA binding activity, and increased the expression of p53 target genes WAF-1, GADD45, and MDM2, leading to cell-cycle arrest in G(1). These results suggest that WR1065 activates p53 through a mechanism distinct from DNA-damage signaling, which involves modulation of p53 protein conformation.
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PMID:Restoration of wild-type conformation and activity of a temperature-sensitive mutant of p53 (p53(V272M)) by the cytoprotective aminothiol WR1065 in the esophageal cancer cell line TE-1. 1187 Aug 84


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