Direct involvement of p53 in the base excision repair pathway of the DNA repair machinery

Offer, Hagai; Wolkowicz, Roland; Matas, Devorah; Blumenstein, Sara; Livneh, Zvi; Rotter, Varda

doi:10.1016/s0014-5793(99)00505-0

Cited by 128 publications

(98 citation statements)

References 71 publications

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“…It was also observed that the human recombinase hRad51 stimulates exonucleolytic DNA degradation by p53, mediated by the ternary complex p53/hRad51/ junction DNA, thus suggesting a model for p53-dependent correction of DNA exchange events (Susse et al, 2000). More recently, it has been shown that RS-p53 can enhance base excision repair in vitro and that both the N-terminal transactivation domain and the central DNA binding domain are required to stimulate this activity (Offer et al, 1999(Offer et al, , 2001Zhou et al, 2001). This activity correlated with the protein's ability to interact directly with the AP endonuclease and with DNA polymerase b (Zhou et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

DNA binding and 3′–5′ exonuclease activity in the murine alternatively-spliced p53 protein

et al. 2002

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In this study we show that the naturally occurring Cterminally alternative spliced p53 (referred to as AS-p53) is active as a sequence-specific DNA binding protein as well as a 3' -5'-exonuclease in the presence of Mg 2+ ions. The two activities are positively correlated as the sequence-specific DNA target is more efficiently degraded than a non-specific target. In contrast, a mutated AS-p53 protein that is deficient in DNA binding lacks exonuclease activity. The use of modified p53 binding sites, where the 3'-phosphate is replaced by a phosphorothioate group, enabled the inhibition of DNA degradation under the binding conditions. We demonstrate that AS-p53 interacts with its specific DNA target by two distinct binding modes: a high-affinity mode characterized by a low-mobility protein-DNA complex at the nanomolar range, and a low-affinity mode shown by a high-mobility complex at the micromolar range. Comparison of the data on the natural and the modified p53 binding sites suggests that the high-affinity mode is related to AS-p53 function as a transcription factor and that the low-affinity mode is associated with its exonuclease activity. The implications of these findings to a specific cellular role of AS-p53 are discussed.

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Section: Discussionmentioning

confidence: 99%

DNA binding and 3′–5′ exonuclease activity in the murine alternatively-spliced p53 protein

et al. 2002

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“…p53-dependent BER repair occurs in vivo and does not depend on p53 transactivation activity (Offer et al, 1999). There is a possibility that in non-stressed cells, in an endogenous DNA damage status, p53 in the nucleus is more competent for the p53-associated BER pathway than for 3 0 -5 0 exonuclease activity.…”

Section: Discussionmentioning

confidence: 99%

“…The transactivationindependent functions of p53 include DNA repair through nonsequence-specific DNA binding. Indeed, p53 acts in nucleotide excision repair (NER) to eliminate pyrimidine dimers caused by UV light (Hwang et al, 1999) and in base excision repair (BER) caused by DNA hydrolysis and alkylation (Offer et al, 1999;Zhou et al, 2001). Hence, by sequence-specific and nonsequencespecific DNA binding, p53 as the 'guardian of the genome' might regulate the cellular response to DNA damage in concert with the DNA repair machinery in order to select among multiple pathways toward DNA repair and apoptosis.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, by sequence-specific and nonsequencespecific DNA binding, p53 as the 'guardian of the genome' might regulate the cellular response to DNA damage in concert with the DNA repair machinery in order to select among multiple pathways toward DNA repair and apoptosis. Interestingly, while sequencespecific transactivation of p53 target genes is dependent on post-translational modification of p53 after DNA damage, all other activities could be displayed by a noninduced p53; for example, it may play a role in ribosomal biogenesis (Marechal et al, 1994); it may actively participate in BER (Offer et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

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p53-associated 3′→5′ exonuclease activity in nuclear and cytoplasmic compartments of cells

et al. 2003

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The tumor suppressor protein p53 plays an important role in maintenance of the genomic integrity of cells. p53 possesses an intrinsic 3 0 -5 0 exonuclease activity. p53 was found in the nucleus and in the cytoplasm of the cell. In order to evaluate the subcellular location and extent of p53-associated 3 0 -5 0 exonuclease activity, we established an in vitro experimental system of cell lines with different nuclear/cytoplasmic distribution of p53. Nuclear and cytoplasmic extracts obtained from LCC2 cells (expressing a high level of cytoplasmic wild-type p53), MCF-7 cells (expressing a high level of wild-type nuclear p53), MDA cells (expressing mutant p53) and H1299 cells (p53-null) were subjected to the analysis of exonuclease activity. Interestingly, 3 0 -5 0 exonuclease was predominantly cytoplasmic; the nuclear extracts derived from all cell lines tested, exerted a low level of exonuclease activity. Cytoplasmic extracts of LCC2 cells, with a high level of wild-type p53, showed an enhanced exonuclease activity in comparison to those expressing either a low level of wild-type p53 (in MCF-7 cells) or the mutant p53 (in MDA cells). Evidence that exonuclease function detected in cytoplasmic extracts is attributed to the p53 is supported by several facts: First, this activity closely parallels with levels and status of endogenous cytoplasmic p53. Second, immunoprecipitation of p53 from cytoplasmic extracts of LCC2 cells markedly reduced the exonuclease activity. Third, the observed 3 0 -5 0 exonuclease in cytoplasmic fraction of LCC2 cells displays identical biochemical properties characteristic of recombinant wild-type p53. The biochemical functions include: (a) substrate specificity; exonuclease hydrolyzes singlestranded DNA in preference to double-stranded DNA and RNA/DNA template-primers, (b) efficient excision of 3 0 -terminal mispairs from DNA/DNA and RNA/DNA substrates, (c) the preferential excision of purine-purine mispairs over purine-pyrimidine mispairs and (d) functional interaction with exonuclease-deficient DNA polymerase, for example, murine leukemia virus reverse transcriptase (representing a relatively low fidelity enzyme), thus enhancing the fidelity of DNA synthesis by excision of mismatched nucleotides from the nascent DNA strand. Taken together, the data demonstrate that wildtype p53 in cytoplasm, in its noninduced state, is functional; it displays intrinsic 3 0 -5 0 exonuclease activity. The possible role of p53-associated 3 0 -5 0 exonuclease activity in DNA repair in nucleus and cytoplasm is discussed.

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“…Thus, p53 can modulate the activities of these helicases, as well as the functions associated with them, including DNA repair. Base excision repair (BER), a DNA repair pathway specialized in the excision of single damaged-base residues, is also enhanced by p53 (46), and Ref-1 APE1, a multi-functional protein that serves as the abasic (A P) endonuclease in BER, can regulate transactivation and the apoptotic functions of p53 (47). In addition to contributing to the repair of DNA damage, p53 can also trigger cell-cycle checkpoints or induce cell death by apoptosis to avoid the xation of mutations that may arise from unrepaired DNA damage.…”

Section: Ner -Associated Helicases: Xpd and Xpbmentioning

confidence: 99%

p53-Mediated Apoptosis and Genomic Instability Diseases

Robles

2001

Acta Oncologica

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Direct involvement of p53 in the base excision repair pathway of the DNA repair machinery

Cited by 128 publications

References 71 publications

DNA binding and 3′–5′ exonuclease activity in the murine alternatively-spliced p53 protein

DNA binding and 3′–5′ exonuclease activity in the murine alternatively-spliced p53 protein

p53-associated 3′→5′ exonuclease activity in nuclear and cytoplasmic compartments of cells

p53-Mediated Apoptosis and Genomic Instability Diseases

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