Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.5.1.2 (DNA ligase)
 2,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. DNA damage by peplomycin, an antitumor antibiotic, and its repair by cellular enzymes were studied using pUC18 plasmid DNA. The DNA damage and repair were measured by monitoring the conformational changes of pUC18 DNA. 2. Peplomycin-induced DNA damage was enhanced by addition of ferrous ion and inhibited by deferoxamine, a specific iron chelator, suggesting iron-requirement for the DNA damage. 3. DNA damage by peplomycin was inhibited by superoxide dismutase in both native and heat-inactivated forms, possibly due to non-enzymatic interaction. 4. Peplomycin-induced, single-strand breaks in pUC18 DNA was repaired by incubating with a priming factor (an exonuclease purified from mouse ascites sarcoma cells), DNA polymerase beta, four deoxynucleoside triphosphates, T4 DNA ligase and ATP. The average repair patch size was estimated to be approximately four nucleotide length.
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PMID:DNA damage by peplomycin and its repair in an in vitro system. 171 61

Repair of X-ray-induced single-strand breaks of DNA was studied in vitro using an exonuclease purified from mouse ascites sarcoma (SR-C3H/He) cells. X-ray-dose-dependent unscheduled DNA synthesis was primed by the exonuclease. Repair of X-ray-induced single-strand breaks in pUC19 plasmid DNA was demonstrated by agarose gel electrophoresis after incubating the damaged DNA with the exonuclease, DNA polymerase (Klenow fragment of DNA polymerase I or DNA polymerase beta purified from SR-C3H/He cells), four deoxynucleoside triphosphates, ATP and DNA ligase (T4 DNA ligase or DNA ligase I purified from calf thymus). The present results suggested that the exonuclease is involved in the initiation of repair of X-ray-induced single-strand breaks in removing 3' ends of X-ray-damaged DNA.
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PMID:Repair of X-ray-induced single-strand breaks by a cell-free system. 237 79

To study the mechanism of DNA excision repair, a DNA repair system employing permeable mouse sarcoma (SR-C3H/He) cells was established and characterized. SR-C3H/He cells were permeabilized with a 0.0175% Triton X-100 solution. The permeable cells were treated with 1 mM ATP and 0.11 mM bleomycin, and then washed thoroughly to remove ATP and bleomycin. Repair DNA synthesis occurred in the bleomycin-damaged, permeable SR-C3H/He cells when incubated with ATP and four deoxyribonucleoside triphosphates. The repair nature of the DNA synthesis was confirmed by the BrdUMP density shift technique, and by the reduced sensitivity of the newly synthesized DNA to Escherichia coli exonuclease III. The DNA synthesis was optimally enhanced by addition of 0.08 M NaCl. Studies using selective inhibitors of DNA synthesis showed that aphidicolin-sensitive DNA polymerase (DNA polymerase alpha and/or delta) and DNA polymerase beta were involved in the repair process. The present DNA repair system is thought to be useful to study nuclear DNA damage by bleomycin, removal of the damaged ends by an exonuclease, repair DNA synthesis by DNA polymerases and repair patch ligation by DNA ligase(s).
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PMID:Studies on bleomycin-induced repair DNA synthesis in permeable mouse ascites sarcoma cells. 247 92

A new method for the production of a chimeric protein of two related genes has been developed. The nucleotide sequences of the region from the N terminus to the 86th amino acid (aa) residue of human N-ras and of the Harvey sarcoma virus (Ha-MuSV) H-ras are 80% homologous. We isolated the DNA fragment encoding the N-terminal portion up to the 70th aa residue from plasmid pH-1 which encodes the total genome of Ha-MuSV, and the DNA fragment encoding the C-terminal portion from the 40th aa to the C terminus from plasmid p6a1 which includes the human N-ras cDNA but lacks the N-terminal portion. After partial digestion of both fragments with phage lambda exonuclease, which creates 3'-protruding ends, a hybrid was formed between 73% homologous single-stranded DNA portions at the 3' ends of both fragments. The hybrid was recloned on pBR322 after repairing with Escherichia coli DNA polymerase I and DNA ligase. The chimeric v-H/N-ras gene composed of the N-terminal portion of v-H-ras gene and the remaining region of N-ras gene was inserted into an expression vector containing two tandem trp promoters and a terminator, and expressed in E. coli. The chimeric protein was found to accumulate to approx. 10% of total cellular proteins.
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PMID:Production of chimeric protein coded by the fused viral H-ras and human N-ras genes in Escherichia coli. 303 85

1. Nilemycin (NM) is found to exert an inhibitory effect on the mouse tumor Sarcoma 180 near toxic doses but not with Leukemia 1210. 2. In Yoshida rat sarcoma cells NM inhibits cellular de novo nucleic acid synthesis and protein to a much lesser extent. 3. More than 50% inhibition by NM to de novo synthesis of RNA, in a system using calf thymus DNA as a template, could be observed. 4. Suitable levels of NM reduce the S values of DNA. 5. The antibiotic induced metachromatic changes in the u.v. spectrum of DNA solutions. 6. NM markedly inhibited the polynucleotide ligase repairing action on DNase-1-nicked DNA. 7. It is presumed that NM intercalates nicked DNA into such a configuration that the reactive sites of the polynucleotides are inaccessible to the ligase activities.
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PMID:Nilemycin, an intercalating agent for deoxyribonucleic acid. 618 40

Purification and characterization of a DNA repair enzyme having 5' apurinic/apyrimidinic (AP) endonuclease activity are reported. The enzyme extracted from mouse ascites sarcoma (SR-C3H/He) cells with 0.2 M potassium phosphate buffer (pH 7.5) was purified by successive chromatographies on phosphocellulose, DEAE-cellulose, phosphocellulose (a second time) and single-stranded DNA cellulose, and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The purified enzyme has an apparent molecular mass of 30 kDa as determined by SDS-PAGE. It was shown to have nicking activity on acid-depurinated DNA but not on intact DNA, and to have priming activities for DNA polymerase on acid-depurinated DNA and bleomycin-treated DNA. The results indicate that it is a multifunctional DNA repair enzyme having 5' AP endonuclease and DNA 3' repair diesterase activities. The enzyme activity is dependent upon the presence of a divalent cation such as Mg2+. Its amino-terminal amino acid and internal amino acid sequences are determined.
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PMID:Purification and characterization of an AP endonuclease/DNA 3' repair diesterase from mouse ascites sarcoma cells. 854 4

In vivo DNA damage and repair was induced by nicotinamide (NAM) in adenotype 12 virus-induced mouse sarcoma A12B3 and sarcoma F inoculated into CBA mice. DNA damage, NAM and NAD concentrations were measured after in vivo exposure to NAM, in tumours and spleens by alkaline elution and by HPLC analysis. Our results indicate that NAM between 100-1000 mg kg-1 causes a high level of in vivo DNA strand breaks in tumours and normal tissues in mice bearing the immunogenic sarcoma A12B3 but not in the non-immunogenic sarcoma F. The repair process was also delayed by the NAM treatment probably owing to inhibition of the DNA repair enzyme, poly(ADP-ribose)polymerase, as evidenced by accumulation of NAM and NAD. These data are consistent with NAM having a mechanism of action as a radiosensitiser at least in part by DNA repair inhibition. In addition, it should also be considered that high doses of NAM might cause considerable complications to normal tissue in tumour-bearing individuals.
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PMID:DNA damage and repair in tumour and non-tumour tissues of mice induced by nicotinamide. 869 50

The presence of cancer stem cells in both solid and hematopoietic malignancies, has been recently linked to their pathogenesis. Sarcomas are rare, and diversely characterized by degrees of mesenchymal differentiation. The aim of the current study was to demonstrate whether the human sarcoma cell lines, osteosarcoma MG63, Ewing's sarcoma HTB166, fibrosarcoma HT1080, possess the stem-like properties which may contribute to the drug-resistance. All cell lines possessed an ability to form spherical, clonal expanding colonies (sarcospheres) in anchorage-independent, serum-starved conditions. Sarcospheres showed the stem-like properties with the ability of self-renewal, and increased expression of the stem cell-related genes such as Nanog, OCT3/4 SOX2 and DNA repair enzyme genes, MLH1 and MSH2. Sarcospheres showed strong resistance to doxorubicin and cisplatin, and caffeine, a DNA repair inhibitor, enhanced the efficacy of those drugs, suggesting that the drug resistance in sarcosphere cells was partly related to the efficient DNA repair ability. These results indicate that human sarcoma cell lines contain stem-like cell populations with strong drug resistance, and DNA repair inhibitor could enhance the efficacy of chemo-drugs against sarcomas.
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PMID:Sphere-forming stem-like cell populations with drug resistance in human sarcoma cell lines. 1936 Mar 50