Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.25.1 (deoxyribonuclease)
 1,471 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The SKH-1 hairless mouse strain has been used extensively as a model for human photocarcinogenesis, photoimmunology and photoaging, but little is known about DNA repair in living mouse skin. Mice were irradiated with UV-B light at doses which produce mild to severe sunburn, and the frequency of pyrimidine dimers in epidermal DNA was measured immediately and 6 h after irradiation using T4 endonuclease V treatment and alkaline agarose gel electrophoresis. The results demonstrate significant removal of pyrimidine dimers in mouse skin in vivo, with a dimer half-life of 7.4 h. These findings are similar to the repair of dimers in human skin in vivo. The SKH-1 hairless mouse is thus a useful model for pyrimidine dimer repair in human skin.
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PMID:SKH-1 hairless mice repair UV-induced pyrimidine dimers in epidermal DNA. 212 22

Ultraviolet (UV) irradiation produces two major photoproducts, cyclobutane pyrimidine dimers (CPD) and (6-4) photoproducts. T4 endonuclease V (T4N5), which specifically repairs CPD, is encapsulated in liposomes. A previous study has shown that UV-induced carcinogenesis in mice was suppressed by the application of T4N5 liposomes. To confirm the suppressive effect, we applied T4N5 liposomes with repeated UVB exposure to hairless mice. At the end of the experiment, mice treated with T4N5 liposomes had 3.5 +/- 1.3 tumors per mouse, and control mice had 6.3 +/- 2.8 tumors per mouse. In addition, the incidence of tumors was reduced in T4N5 liposome-treated mice compared with controls. The pathological diagnosis of the tumors was not significantly different between two groups. Immunohistochemical analysis of p53 protein in UV-induced tumors showed that nearly half of the tumors in both groups were positive. When the biopsied normal-looking skin taken during the experiment was stained with p53 antibody, there was no significant difference of the timing of p53 protein expression between the control mice and T4N5 liposome-treated mice. These results confirmed that CPD plays a pivotal role in UV carcinogenesis, although the molecular mechanisms of the suppression by T4N5 liposomes should be further clarified.
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PMID:Reduction of ultraviolet-induced skin cancer in mice by topical application of DNA excision repair enzymes. 765 67

Removal of UVB-induced cyclobutane pyrimidine dimers (CPD) from each of the two strands of the transcriptionally active p53 tumor suppressor gene and the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene was determined in the epidermis of the hairless mouse using the CPD-specific enzyme T4 endonuclease V. Mice were exposed to a single dose of UVB (2 kJ/m2) and kept in darkness for up to 24 h. About 80% of the CPD were removed from the transcribed strand of the p53 and HPRT genes within 24 h. Most rapid removal was observed during the first 4 h. In contrast, very little removal of CPD from the nontranscribed strand of the p53 and the HPRT genes was observed in 24 h. The same low level of repair was observed in the inactive c-mos proto-oncogene. The efficient repair of the transcribed strand compared to the nontranscribed strand of transcriptionally active genes in the epidermis of the hairless mouse resembles the repair of CPD in cultured rodent cells. Moreover, the selective removal of CPD from the transcribed strand of the p53 gene correlates well with the known strand bias of u.v.-induced mutations at dipyrimidine sites in the p53 gene of u.v.-induced mouse skin tumors.
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PMID:Strand-specific removal of cyclobutane pyrimidine dimers from the p53 gene in the epidermis of UVB-irradiated hairless mice. 797 Jul 1

This study describes the induction and repair of UV-induced cyclobutane pyrimidine dimers (CPD) in transcriptionally active and inactive genes in the epidermis of the hairless mouse. Mice were exposed to a single dose of 2000 J/m2 ultraviolet B and kept in darkness for up to 24 h. The CPD frequency was measured in the transcriptionally active hypoxanthine-guanine phosphoribosyltransferase gene, the adenosine deaminase gene, the inactive c-mos protooncogene, and the haptoglobin gene using the CPD-specific enzyme T4 endonuclease V. Sixty % of the CPD was removed from the active genes during the first 4 h, after which no further repair took place up to 24 h. In contrast, the inactive genes did not show any removal of CPD. Assuming that the rate of repair in the c-mos and haptoglobin genes is representative for the repair rate in the genome overall, these results suggest only marginal repair of UV-induced CPD in the mouse epidermis in vivo. The selective repair of active genes in the epidermis of mice resembles that of rodent cells in culture and shows the biological relevance of repair studies performed with cultured rodent cells in vitro.
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PMID:Ultraviolet-induced cyclobutane pyrimidine dimers are selectively removed from transcriptionally active genes in the epidermis of the hairless mouse. 845 36