Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The covalently closed circular forms of unintegrated viral DNA obtained from cells infected with Moloney mouse sarcoma virus was cloned in bacteriophage lambda. The viral DNA was cleaved with restriction endonuclease HindIII and inserted in the unique HindIII site of lambda Charon 21A DNA. Recombinant clones containing virus-reactive DNA sequences were analyzed by restriction endonuclease mapping, R-loop formation, and infectivity assays. Two of eight genome-length recombinant clones characterized contained the large terminal repeat. Only the recombinant clones containing the large terminal repeat were able to induce focus formation in uninfected mouse fibroblasts.
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PMID:Molecular cloning of unintegrated Moloney mouse sarcoma virus DNA in bacteriophage lambda. 644 61

Both the pattern and level of rRNA gene methylation vary in the rat. This variation reflects stages in the maturation process and perhaps the level of gene expression in different tissues. We studied methylation at a common site, the inner cytosine of the sequence CCGG, by hybridizing 32P-rRNA to DNA digests obtained with endonuclease Msp I (which cleaves CCGG and CMCGG) and its isochizomer, HpaII (which cleaves only CCGG). In the liver, the changing pattern of rRNA gene methylation reflected the late stages of development: the rRNA genes were mostly unmethylated at 14 days gestation; by 18 days gestation, about 30% of them were methylated, and this level persisted into adulthood. In 18-day DNA, the methylation was uniform, but in adult DNA, the methylation pattern was discontinuous, because otherwise methylated genes contained a demethylated region. Similar developmental changes were observed in brain DNA. In a tissue culture cell line, the change from the continuous to the discontinuous pattern of the methylation could be induced by transformation with Kirsten sarcoma virus. And, in adult tissues, the lowest level of rRNA gene methylation was found in rapidly growing jejunal epithelium, and the highest level, in non-growing spermatozoa.
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PMID:Variable methylation of the ribosomal RNA genes of the rat. 711 Oct 24

Although VL30 retrotransposable elements have been associated with certain cancers for nearly twenty years, because of their expression in rodent malignancies and recombination into murine sarcoma viruses, their causative role, if any, in cancer has been uncertain and enigmatic. Recent findings suggest loss of normal transcriptional control of specific VL30 element expression may make a critical contribution to tumor progression at a step associated with malignant conversion, by bringing into play a cellular program normally involved in wound healing. This program, the fibroblast anoxic response system, includes an adaptation to glycolytic metabolism, secretion of metalloproteinases, and activation of an endonuclease. While appropriate for facilitating debris removal during wound healing, loss of control of this program in a cell which has already progressed to the benign neoplastic state has the potential to simultaneously produce the invasiveness and genomic instability characteristic of malignancy. Examination of tumors and tumor derived cell lines has confirmed that key aspects of this system are in fact activated in cancer.
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PMID:Anoxia, wound healing, VL30 elements, and the molecular basis of malignant conversion. 839 Aug 32

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

We purified an apurinic/apyrimidinic (AP) endonuclease from mouse ascites sarcoma (SR-C3H/He) cells. The enzyme showed nicking activity on acid-depurinated DNA but not on untreated, intact DNA. It also showed priming activity for DNA polymerase on both acid-depurinated and bleomycin-damaged DNA. The priming activity on bleomycin-damaged DNA was two times higher than that on an acid-depurinated DNA. The enzymatic properties indicate that the enzyme is a class II AP endonuclease having DNA 3' repair diesterase activity. The purified enzyme has a molecular weight of 39,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The optimal pH for AP endonuclease activity was 8.0 in 50 mM Tris-HCl buffer. The AP endonuclease activity depended on divalent cation such as Mg2+ and Co2+ ions, and was inhibited by 2 mM EDTA with no addition of the divalent cation. An appropriate concentration of sodium or potassium salt stimulated the activity. Partial digestion of the AP endonuclease with Staphylococcus aureus V8 protease produced 4 major peptide fragments which may be used for protein sequencing.
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PMID:Purification and characterization of a 39kDa apurinic/apyrimidinic endonuclease from mouse ascites sarcoma cells. 880 52

We purified a 44-kDa nuclear protein from salt-extract of permeable mouse ascites sarcoma cells in an effort to isolate factors involved in the repair of acid-depurinated DNA. It was copurified with a major AP endonuclease (APEX nuclease) by sequential column chromatography then further purified by sodium dodecyl sulphate-polyacrylamide gel electrophoresis as a possible DNA repair support factor. Its partial amino acid sequences were determined, and a cDNA clone for the protein was isolated from a mouse T-cell cDNA library using long degenerate oligonucleotide probes deduced from the amino acid sequence. The complete nucleotide sequence of the cDNA (1.7 kilobases) was determined. Northern hybridization using this cDNA detected two transcripts: 1.8 kb being the major one and 2.6 kb being the minor one. The complete amino acid sequence for the protein predicted from the nucleotide sequence of the cDNA indicates that the 44-kDa protein consists of 394 amino acids with a calculated molecular weight of 43,698. In tests performed thus far, the recombinant 44-kDa protein expressed in Escherichia coli has not expressed any repair-support activity. It remains to be analyzed whether the protein attains this activity after appropriate posttranslational modifications. Most parts of the 44-kDa protein cDNA and the deduced amino acid sequence were found to be identical to those of the protein p38-2G4, recently reported as a cell cycle-specifically modulated nuclear protein of 38kDa. The p38-2G4 may be a truncated form of the present 44-kDa protein.
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PMID:cDNA cloning, sequence analysis and expression of a mouse 44-kDa nuclear protein copurified with DNA repair factors for acid-depurinated DNA. 928 67

Mitochondria from a patient heteroplasmic at nucleo-tide position 8993 of mitochondrial DNA (mtDNA) were introduced into two human tumour cell lines lacking mtDNA. The donor mitochondria contained between 85 and 95% 8993G:C mtDNA. All detectable mtDNA in the mitochondrially transformed cells contained the pathological 8993G:C mutation 3 months after transformation. These results suggest that 8993G:C mtDNA had a selective advantage over 8993T:A mtDNA in both lung carcinoma and osteo-sarcoma cell backgrounds. In contrast, two other presumed pathological mtDNA variants were lost in favour of 'wild-type' mtDNA molecules in the same lung carcinoma cell background. Taken together, these findings suggest that the transmission bias of mtDNA variants is dependent upon a combination of nuclear background and mtDNA genotype. A second phenomenon observed was a marked decrease in the growth rate of many putative transformed cell lines after 6 weeks of culturing in selective medium, and in these cell lines mtDNA was not readily detectable by Southern blotting. Restriction endonuclease analysis and sequencing of amplified mtDNA demonstrated that the slow growing cells contained little or no mtDNA. It is concluded that these cells represented transient mitochondrial transformants.
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PMID:Introduction of heteroplasmic mitochondrial DNA (mtDNA) from a patient with NARP into two human rho degrees cell lines is associated either with selection and maintenance of NARP mutant mtDNA or failure to maintain mtDNA. 1044 39

FLT3 is one of the most frequently mutated genes in acute myeloid leukemia. Previous studies have reported FLT3 mutation in as many as 9.2% of myeloproliferative neoplasms (MPNs) and myelodysplastic/myeloproliferative neoplasms (MDS/MPNs), as well as in chronic myelogenous leukemia, that are negative for the JAK2 V617F gene mutation; no FLT3 mutation has been found in JAK2-positive MPNs, suggesting that the mutations are mutually exclusive. The goal of our study is to evaluate the mutational status of the FLT3 gene in patients with an MPN or MDS/MPN, in correlation with the JAK2 mutational status. Patient specimens were retrospectively identified on the basis of MPN or MDS/MPN diagnosis and JAK2 analysis from February 2006 to December 2011. FLT3 mutation analysis was performed on DNA extracted from 152 patients using polymerase chain reaction amplification and analysis of amplicons by gel electrophoresis for internal tandem duplication mutations and by restriction endonuclease digestion fragment analysis for the D835 point mutation. FLT3 mutation analysis was performed on 90 cases of JAK2-negative MPN or MDS/MPN and 62 cases of JAK2-positive MPN. One FLT3 internal tandem duplication mutation was identified in the JAK2-negative group (1.1%), and none were identified in the JAK2-positive group, confirming the absence of FLT3 mutations in JAK2-positive specimens. The FLT3-positive MPN patient was diagnosed with MPN, unclassifiable, and was later found to have myeloid sarcoma; thus, FLT3 mutation was not seen in the usual types of MPN in our series. Our result of 1.1% FLT3 mutations in JAK2-negative MPN and MDS/MPN cases is lower than the 9.2% previously reported.
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PMID:FLT3 mutations in myeloproliferative neoplasms: the Beaumont experience. 2384 42


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