Enhanced DNA binding capacity on up‐regulated epidermal wild‐type p53 in vitiligo by H 2 O 2 ‐mediated oxidation: a possible repair mechanism for DNA damage

2009 ◽  
Vol 23 (11) ◽  
pp. 3790-3807 ◽  
Author(s):  
Mohamed M. A. E. L. Salem ◽  
Mohammad Shalbaf ◽  
Nicholas C. J. Gibbons ◽  
Bhaven Chavan ◽  
J. M. Thornton ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Binding ◽  
Binding Capacity ◽  
Wild Type ◽  
Repair Mechanism ◽  
Wild Type P53 ◽  
Mediated Oxidation

Role of P53 Mutations in the Radiosensitivity Status of Tumor Cells

1998 ◽  
Vol 84 (5) ◽  
pp. 517-520 ◽  
Author(s):  
Vincenzo Chiarugi ◽  
Lucia Magnelli ◽  
Marina Cinelli
Keyword(s):  
Dna Damage ◽  
Cellular Response ◽  
P53 Protein ◽  
Cell Cycle Control ◽  
P53 Mutations ◽  
Wild Type ◽  
Bladder Tumors ◽  
Variable Effect ◽  
Wild Type P53

Wild-type p53 is involved in cellular response to DNA damage including cell cycle control, DNA repair and activation of apoptosis. Accumulation of p53 protein following DNA damage may initiate the apoptotic process, resulting in cell death. DNA damage induced by radiation is an example of apoptotic stimulus involving p53. Regulation of apoptosis by p53 can occur through transcriptional regulation of pro-apoptotic (e.g. bax) and anti-apoptotic (e.g. bel-2) factors. Although wild-type p53 usually sensitizes cells to radiation therapy, p53 mutations have a variable effect on radiation response. For example p53 mutations in bone or breast tumors have been found to be associated with resistance to chemotherapeutic drugs or ionizing radiation. Mutated p53 has has been reported to increase sensitivity to radiation and drugs in colorectal and bladder tumors. The present brief commentary tries to find an explanation at molecular level of these conflicting results.

scholarly journals Identification of a minimal transforming domain of p53: negative dominance through abrogation of sequence-specific DNA binding.

1992 ◽  
Vol 12 (12) ◽  
pp. 5581-5592 ◽  
Author(s):  
E Shaulian ◽  
A Zauberman ◽  
D Ginsberg ◽  
M Oren
Keyword(s):  
Dna Binding ◽  
Point Mutation ◽  
P53 Gene ◽  
Dominant Negative ◽  
Mutant P53 ◽  
Wild Type ◽  
Transforming Activity ◽  
Wild Type P53 ◽  
Negative Dominance

Mutations in the p53 gene are most frequent in cancer. Many p53 mutants possess transforming activity in vitro. In cells transformed by such mutants, the mutant protein is oligomerized with endogenous cell p53. To determine the relevance of oligomerization for transformation, miniproteins containing C-terminal portions of p53 were generated. These miniproteins, although carrying no point mutation, transformed at least as efficiently as full-length mutant p53. Transforming activity was coupled with the ability to oligomerize with wild-type p53, as well as with the ability to abrogate sequence-specific DNA binding by coexpressed wild-type p53. These findings suggest that p53-mediated transformation may operate through a dominant negative mechanism, involving the generation of DNA binding-incompetent oligomers.

scholarly journals Down-regulation of Wild-type p53-induced Phosphatase 1 (Wip1) Plays a Critical Role in Regulating Several p53-dependent Functions in Premature Senescent Tumor Cells

2013 ◽  
Vol 288 (23) ◽  
pp. 16212-16224 ◽  
Author(s):  
Elvira Crescenzi ◽  
Zelinda Raia ◽  
Francesco Pacifico ◽  
Stefano Mellone ◽  
Fortunato Moscato ◽  
...  
Keyword(s):  
Dna Damage ◽  
Tumor Cells ◽  
Dna Damage Response ◽  
Critical Role ◽  
Wild Type ◽  
Down Regulation ◽  
Senescent Phenotype ◽  
Response To Chemotherapy ◽  
Damage Response ◽  
Wild Type P53

Premature or drug-induced senescence is a major cellular response to chemotherapy in solid tumors. The senescent phenotype develops slowly and is associated with chronic DNA damage response. We found that expression of wild-type p53-induced phosphatase 1 (Wip1) is markedly down-regulated during persistent DNA damage and after drug release during the acquisition of the senescent phenotype in carcinoma cells. We demonstrate that down-regulation of Wip1 is required for maintenance of permanent G2 arrest. In fact, we show that forced expression of Wip1 in premature senescent tumor cells induces inappropriate re-initiation of mitosis, uncontrolled polyploid progression, and cell death by mitotic failure. Most of the effects of Wip1 may be attributed to its ability to dephosphorylate p53 at Ser15 and to inhibit DNA damage response. However, we also uncover a regulatory pathway whereby suppression of p53 Ser15 phosphorylation is associated with enhanced phosphorylation at Ser46, increased p53 protein levels, and induction of Noxa expression. On the whole, our data indicate that down-regulation of Wip1 expression during premature senescence plays a pivotal role in regulating several p53-dependent aspects of the senescent phenotype.

Bcl-2 Protects against p53-Induced Apoptosis through Hdm2

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5333-5333
Author(s):  
Line Wergeland ◽  
Kevin B. Spurgers ◽  
Eystein Oveland ◽  
Torill Høiby ◽  
Manel Cascallo ◽  
...  
Keyword(s):  
Dna Damage ◽  
Acute Myeloid Leukemia ◽  
Protein Level ◽  
Myeloid Leukemia ◽  
Proteasome Inhibitors ◽  
Wild Type ◽  
Inhibitory Molecule ◽  
Wild Type P53 ◽  
Induced Apoptosis ◽  
Acute Myeloid

Abstract Hdm2 is up-regulated in several malignancies including sarcomas and acute myeloid leukemia, where it counteracts the anti-proliferative and pro-apoptotic effect of wild type p53. The anti-apoptotic protein Bcl-2 is often elevated in many tumors with wild type p53 and serves to block p53-induced apoptosis. We demonstrate that the protein level of Hdm2 positively correlates with the level of Bcl-2 and follows the Bcl-2 level in different cell systems. Over-expression of Bcl-2 protects Hdm2 from DNA-damage induced degradation in a dose dependant manner. In addition, modulation of Bcl-2 by shRNA knockdown reduced the Hdm2 protein level in parallel. Consequently, treatment of AML cells with the Bcl-2 small inhibitory molecule HA14-1 attenuated the level of Hdm2. The Bcl-2 level, but not the DNA damage induced Hdm2 degradation, was affected by disruption of the E3 ubiquitin ligase activity of Hdm2. In addition, the DNA-damage induced Hdm2 down-regulation was blocked by disrupted E1 ubiquitin-activation, defect polyubiquitination and by proteasome inhibitors. Finally, we show that Bcl-2 protection from p53-induced cell death requires co-expression of Hdm2 in double null p53/mdm2 mouse embryonic fibroblasts. Our results indicate that Bcl-2 regulates the Hdm2 level and that Hdm2 is a key mediator in Bcl-2 inhibition of p53-induced apoptosis. This is of particular therapeutic interest for cancers displaying elevated Hdm2 and Bcl-2, like sarcoma and acute myeloid leukemia.

scholarly journals Cu,Zn-superoxide dismutase deficiency in mice leads to organ-specific increase in oxidatively damaged DNA and NF-κB1 protein activity.

2010 ◽  
Vol 57 (4) ◽  
Author(s):  
Agnieszka Siomek ◽  
Kamil Brzoska ◽  
Barbara Sochanowicz ◽  
Daniel Gackowski ◽  
Rafal Rozalski ◽  
...  
Keyword(s):  
Dna Damage ◽  
Superoxide Dismutase ◽  
Dna Binding ◽  
Urinary Excretion ◽  
Oxidative Dna Damage ◽  
Binding Activity ◽  
Wild Type ◽  
Dna Binding Activity ◽  
Organ Specific ◽  
Damaged Dna

Earlier experimental studies have demonstrated that: i) Cu,Zn-superoxide dismutase deficiency leads to oxidative stress and carcinogenesis; ii) dysregulation of NF-κB pathway can mediate a wide variety of diseases, including cancer. Therefore, we decided, for the first time, to examine the level of oxidative DNA damage and the DNA binding activity of NF-κB proteins in SOD1 knockout, heterozygous and wild-type mice. Two kinds of biomarkers of oxidatively damaged DNA: urinary excretion of 8-oxodG and 8-oxoGua, and the level of oxidatively damaged DNA were analysed using HPLC-GC-MS and HPLC-EC. The DNA binding activity of p50 and p65 proteins in a nuclear extracts was assessed using NF-κB p50/p65 EZ-TFA transcription factor assay. These parameters were determined in the brain, liver, kidney and urine of SOD1 knockout, heterozygous and wild-type mice. The level of 8-oxodG in DNA was higher in the liver and kidney of knockout mice than in wild type. No differences were found in urinary excretion of 8-oxoGua and 8-oxodG between wild type and the SOD1-deficient animals. The activity of the p50 protein was higher in the kidneys, but surprisingly not in the livers of SOD1-deficient mice, whereas p65 activity did not show any variability. Our results indicate that in Cu,Zn-SOD-deficient animals the level of oxidative DNA damage and NF-κB1 activity are elevated in certain organs only, which may provide some explanation for organ-specific ROS-induced carcinogenesis.

Prevention of Fluorodeoxyuridine-Induced Cytotoxicity and DNA Damage in HT29 Colon Carcinoma Cells by Conditional Expression of Wild-Type p53 Phenotype

1997 ◽  
Vol 52 (4) ◽  
pp. 600-605 ◽  
Author(s):  
Leslie A. Parsels ◽  
Richard C. Zellars ◽  
Tania L. Loney ◽  
Joshua D. Parsels ◽  
Michael F. Clarke ◽  
...  
Keyword(s):  
Dna Damage ◽  
Colon Carcinoma ◽  
Carcinoma Cells ◽  
Wild Type ◽  
Colon Carcinoma Cells ◽  
Conditional Expression ◽  
Wild Type P53

p53 domains: structure, oligomerization, and transformation

1994 ◽  
Vol 14 (8) ◽  
pp. 5182-5191
Author(s):  
P Wang ◽  
M Reed ◽  
Y Wang ◽  
G Mayr ◽  
J E Stenger ◽  
...  
Keyword(s):  
Amino Acids ◽  
Dna Binding ◽  
Gel Filtration ◽  
Dominant Negative ◽  
Wild Type ◽  
C Terminus ◽  
Tetramerization Domain ◽  
Wild Type P53 ◽  
Negative Phenotype

Wild-type p53 forms tetramers and multiples of tetramers. Friedman et al. (P. N. Friedman, X. B. Chen, J. Bargonetti, and C. Prives, Proc. Natl. Acad. Sci. USA 90:3319-3323, 1993) have reported that human p53 behaves as a larger molecule during gel filtration than it does during sucrose gradient sedimentation. These differences argue that wild-type p53 has a nonglobular shape. To identify structural and oligomerization domains in p53, we have investigated the physical properties of purified segments of p53. The central, specific DNA-binding domain within murine amino acids 80 to 320 and human amino acids 83 to 323 behaves predominantly as monomers during analysis by sedimentation, gel filtration, and gel electrophoresis. This consistent behavior argues that the central region of p53 is globular in shape. Under appropriate conditions, however, this segment can form transient oligomers without apparent preference for a single oligomeric structure. This region does not enhance transformation by other oncogenes. The biological implications of transient oligomerization by this central segment, therefore, remain to be demonstrated. Like wild-type p53, the C terminus, consisting of murine amino acids 280 to 390 and human amino acids 283 to 393, behaves anomalously during gel filtration and apparently has a nonglobular shape. Within this region, murine amino acids 315 to 350 and human amino acids 323 to 355 are sufficient for assembly of stable tetramers. The finding that murine amino acids 315 to 360 enhance transformation by other oncogenes strongly supports the role of p53 tetramerization in oncogenesis. Amino acids 330 to 390 of murine p53 and amino acids 340 to 393 of human p53, which have been implicated by Sturzbecher et al. in tetramerization (H.-W. Sturzbecher, R. Brain, C. Addison, K. Rudge, M. Remm, M. Grimaldi, E. Keenan, and J. R. Jenkins, Oncogene 7:1513-1523, 1992), do not form stable tetramers under our conditions. Our findings indicate that p53 has at least two autonomous oligomerization domains: a strong tetramerization domain in its C-terminal region and a weaker oligomerization domain in the central DNA binding region of p53. Together, these domains account for the formation of tetramers and multiples of tetramers by wild-type p53. The tetramerization domain is the major determinant of the dominant negative phenotype leading to transformation by mutant p53s.

Isolation and characterization of DNA sequences that are specifically bound by wild-type p53 protein

1993 ◽  
Vol 13 (3) ◽  
pp. 1378-1384
Author(s):  
O Foord ◽  
N Navot ◽  
V Rotter
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Dna Sequences ◽  
P53 Protein ◽  
Random Sequence ◽  
Terminal Region ◽  
Sequence Specificity ◽  
Wild Type ◽  
Isolation And Characterization ◽  
Wild Type P53

Wild-type p53 was shown to function as a transcription factor. The N-terminal region of the protein contains the transcription activation domain, while the C terminus is responsible for DNA binding. Localization of the DNA-binding domain of the p53 protein to the highly conserved carboxy-terminal region suggests that the interaction of p53 with DNA is important for its function. We have developed a strategy for studying the DNA sequence specificity of p53-DNA binding that is based on random sequence selection. We report here on the isolation of murine genomic DNA clones that are specifically bound by the wild-type p53 protein but are not bound by mutant p53 protein forms. The isolated p53 target gene contains the unique DNA-binding sequence GACACTGGTCACACTTGGCTGCTTAGGAAT. This fragment exhibits promoter activity as measured by its capacity to activate transcription of the chloramphenicol acetyltransferase reporter gene. Our results suggest that p53 directly binds DNA and functions as a typical transcription factor.

scholarly journals Discrimination of DNA binding sites by mutant p53 proteins.

1995 ◽  
Vol 15 (9) ◽  
pp. 5196-5202 ◽  
Author(s):  
S K Thukral ◽  
Y Lu ◽  
G C Blain ◽  
T S Harvey ◽  
V L Jacobsen
Keyword(s):  
Amino Acid ◽  
Dna Binding ◽  
Base Pair ◽  
Molecular Genetic ◽  
Full Length ◽  
Single Amino Acid ◽  
Wild Type ◽  
Binding Assays ◽  
Wild Type P53

Critical determinants of DNA recognition by p53 have been identified by a molecular genetic approach. The wild-type human p53 fragment containing amino acids 71 to 330 (p53(71-330)) was used for in vitro DNA binding assays, and full-length human p53 was used for transactivation assays with Saccharomyces cerevisiae. First, we defined the DNA binding specificity of the wild-type p53 fragment by using systematically altered forms of a known consensus DNA site. This refinement indicates that p53 binds with high affinity to two repeats of PuGPuCA.TGPyCPy, a further refinement of an earlier defined consensus half site PuPuPuC(A/T).(T/A) GPyPyPy. These results were further confirmed by transactivation assays of yeast by using full-length human p53 and systematically altered DNA sites. Dimers of the pentamer AGGCA oriented either head-to-head or tail-to-tail bound efficiently, but transactivation was facilitated only through head-to-head dimers. To determine the origins of specificity in DNA binding by p53, we identified mutations that lead to altered specificities of DNA binding. Single-amino-acid substitutions were made at several positions within the DNA binding domain of p53, and this set of p53 point mutants were tested with DNA site variants for DNA binding. DNA binding analyses showed that the mutants Lys-120 to Asn, Cys-277 to Gln or Arg, and Arg-283 to Gln bind to sites with noncanonical base pair changes at positions 2, 3, and 1 in the pentamer (PuGPuCA), respectively. Thus, we implicate these residues in amino acid-base pair contacts. Interestingly, mutant Cys-277 to Gln bound a consensus site as two and four monomers, as opposed to the wild-type p53 fragment, which invariably binds this site as four monomers.

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