Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activities of nuclear endonucleases and topoisomerase I were measured in rat fibroblasts which were at the stages of tumor transformation: control embryonal fibroblasts--CEF; cells immortalised by transfection of S1A segment of SA7 adenovirus--REF-1; intermedius cells transfected once by EJras oncogene--REF-1EJ; and cells transformed after the second transfection by the same oncogene--REF-2EJ. The topoisomerase I and Ca2+, Mg2+-dependent endonuclease was most decreased at the stage of immortalised cells, and the intermedius stage (REF-1EJ) was characterized by the lower activity of Ca2+, Mg2+-dependent endonuclease. The highest activity of Mn2+-dependent endonuclease is seen in REF-2EJ cells. In model experiments the ability of Ca2+, Mg2+-dependent endonuclease to split non-stochastically the EJras oncogene inserted into pBR322 plasmid was shown. The role of the investigated enzymes in the restriction of plasmid integration, cellular immortalisation and recombination of plasmids with chromosomes during cell transformation is discussed.
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PMID:[Activity of topoisomerase I and endonucleases in cells transfected by a ras oncogene]. 254

We have cloned mouse and human cDNAs for a multifunctional DNA repair enzyme (APEX nuclease) having apurinic/apyrimidinic (AP) endonuclease, 3',5' exonuclease, DNA 3' repair diesterase and DNA 3'-phosphatase activities. To investigate the biological role of APEX nuclease, sense or antisense APEX RNA was stably expressed at a high level in cultured rat glioma cells by introducing plasmids (pABWN-HAPX1F for expression of sense RNA or pABWN-HAPX2R for expression of antisense RNA) constructed from the human APEX cDNA and an expression vector pABWN. Multiple copies of the construct were integrated into the glioma cells transfected with pABWN-HAPX1F or pABWN-HAPX2R. These transfectants showed markedly high expression of RNA hybridizable to human APEX cDNA, indicating the expression of the sense or antisense RNA. Activity blotting analyses of salt extracts of these transfectants showed that the sense RNA-expressed cells had higher AP endonuclease activity and that the antisense RNA-expressed cells had extremely lower AP endonuclease activity than the control cells. The APEX nuclease-depressed glioma cells became more sensitive to methyl methanesulfonate and hydrogen peroxide than the control cells or the APEX nuclease-overexpressed cells. The results indicate that APEX nuclease plays an important role in repair of DNA damage caused by these genotoxic agents. The present stable expression systems for the sense and antisense APEX RNAs should be useful for analyzing the biological functions such as an antimutagenic function of the enzyme.
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PMID:Stable expression in rat glioma cells of sense and antisense nucleic acids to a human multifunctional DNA repair enzyme, APEX nuclease. 751 11

Expression of the mammalian major apurinic/apyrimidinic (AP) endonuclease (designated as APEX nuclease, or HAP1, APE or Ref-1 gene product) during mouse brain development was investigated by in situ and northern blot hybridizations. The enzyme is known to be a redox factor (Ref-1) stimulating DNA binding activity of AP-1 binding proteins such as Fos and Jun as well as a multifunctional DNA repair enzyme having 5' AP endonuclease, DNA 3' repair diesterase, 3'-5' exonuclease and DNA 3'-phosphatase activities. In the embryonic and postnatal development, APEX mRNA was expressed at high levels in the proliferative zone of various brain regions, with showing temporal and spatial changes. Its expression decreased in association with brain development to the basal expression level which was observed even in adulthood, with the exception of its expression in the hippocampal formation. The growth-dependent expression of APEX gene suggests that it has some roles on cell proliferation and/or differentiation in developmental brain. Its expression on the hippocampal formation became significant from postnatal day 7 and then increased. The pyramidal and granule cell layers expressed it at a higher level than most other brain regions at postnatal day 21. The developmental change of APEX gene expression was not necessarily associated with the changes of expression of c-fos and c-jun genes measured by northern blot hybridization. However, the present results suggested that APEX/Ref-1 gene product can interact with AP-1 binding proteins in brain, especially in the hippocampal formation, to regulate some brain functions by redox-activation.
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PMID:Developmental expression of APEX nuclease, a multifunctional DNA repair enzyme, in mouse brains. 765 3

Drosophila Rrp1 (Recombination repair protein 1) belongs to a family of DNA repair nucleases that includes Escherichia coli exonuclease III, Streptococcus pneumoniae exonuclease A, bovine BAP, mouse APEX endonuclease, and human APE. Within a 252 amino acid region, colinear homology is shared between all members. Rrp1 is unique in that it includes a 427 amino acid N-terminal region not related to any known sequence. The protein copurifies with an apurinic endonuclease and a double-stranded DNA 3'-exonuclease. In this study, a 5'-end-labeled 37 base pair oligonucleotide substrate containing a single apurinic site was used to characterize the endonuclease activity of Rrp1. This substrate is utilized efficiently by Rrp1: the specific activity observed is 1 x 10(5) units/mg. The abasic double-stranded DNA oligonucleotide is cleaved only at the abasic site to create a single-strand break. Strand breaks are not detected in the complementary strand, in the single-stranded DNA oligonucleotide, or in the base-paired control substrate. After endonucleolytic cleavage at the abasic site, exonucleolytic processing at the nick is slow and requires a molar excess of Rrp1, while exonuclease III degrades the nicked substrate more efficiently. The Rrp1 cleavage product comigrates with a DNaseI cleavage product, and the newly formed terminus supports DNA synthesis by DNA polymerase. Therefore, Rrp1 cleaves the phosphodiester backbone at one position 5' to the apurinic site and leaves a 3'-hydroxyl terminus. Rrp1 is a class II apurinic endonuclease and is likely to be important in DNA repair in Drosophila.
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PMID:Characterization of the apurinic endonuclease activity of Drosophila Rrp1. 769 63

1. Sequence analyses of APEX nuclease, a mammalian major apurinic/apyrimidinic (AP) endonuclease homologous to Escherichia coli exonuclease III, suggested that APEX nuclease is organized into two domains, a Mr 6000 N-terminal domain containing nuclear location signals and a Mr 29,000 C-terminal catalytic domain. 2. In order to study the enzyme structure further, vectors expressing APEX nuclease (pTAPXH1) and the Mr 29,000 C-terminal region (pTAPXH61) were constructed using cDNA (APX cDNA) for the human APEX nuclease and pTrc99A plasmid. The constructs were introduced into BW2001 strain (xth-11, nfo-2) cells of E. coli to produce transformants designated as BW2001/pTAPXH1 and BW2001/pTAPXH61, respectively. Both the APEX nuclease expressed in BW2001/pTAPXH1 and the Mr 29,000 C-terminal peptide expressed in BW2001/pTAPXH61 were partially purified by column chromatography and highly purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 3. The purified APEX nuclease and the Mr 29,000 C-terminal peptide both showed equally high AP endonuclease activity which indicates that the Mr 29,000 C-terminal region of the APEX nuclease is (or contains) the AP endonuclease domain.
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PMID:Expression of a putative catalytic domain of the human APEX nuclease (a major apurinic/apyrimidinic endonuclease) in Escherichia coli. 846 27

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

The multifunctional DNA repair enzyme (APEX nuclease) having apurinic/apyrimidinic (AP) endonuclease, 3'-5' exonuclease, DNA 3' repair diesterase and DNA 3'-phosphatase activities is thought to be involved in repair of AP sites and single-strand breaks with 3'-blocked termini. To investigate the biological role of the enzyme, we studied the correlation between APEX AP endonuclease activity in several human glioma cell lines having various degree of its expression and cellular susceptibility to cytotoxic agents such as methyl methanesulfonate (MMS), 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3- (2-chloroethyl)-3-nitrosourea hydrochloride (ACNU), cis-diamminedichloroplatinum(II) (CDDP), etoposide (VP-16), hydrogen peroxide (H2O2), hyperthermia and X-ray. The cell lines having lower APEX expression showed higher sensitivity to MMS and H2O2 which are known to induce AP sites and single strand breaks on DNA, respectively. The cellular susceptibility to the other agents tested was not significantly correlated to the APEX expression. The present results are thought to support the notion that APEX nuclease plays an important role on repair of AP sites and single-strand DNA breaks with 3'-blocked termini in mammalian cells.
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PMID:Relationship between expression of a major apurinic/apyrimidinic endonuclease (APEX nuclease) and susceptibility to genotoxic agents in human glioma cell lines. 859 68

We investigated the minimal promoter of APEX, which encodes mouse apurinic DNA repair endonuclease. A 1.85-kb fragment with APEX upstream sequences and approximately 290 bp of the transcribed region linked to a chloramphenicol acetyltransferase (CAT) reporter gene was assayed by transient transfection in NIH-3T3 cells. The minimal APEX promoter was comprised of approximately 190 bp of upstream and approximately 170 bp of transcribed DNA (exon 1 and most of intron 1). This approximately 360-bp region contains two CCAAT boxes and other consensus protein binding sites, but no TATA box. Deletion of the 5'-most CCAAT box decreased activity approximately 5-fold. The second CCAAT box (situated in exon 1) may play an independent role in APEX expression. Transcription start sites have been identified downstream of the second CCAAT box, and DNase I footprinting demonstrated NIH-3T3 nuclear proteins binding this region, including an Spl site located between the CCAAT boxes. Electrophoretic mobility-shift assays indicated binding by purified Sp1. Mouse proteins did not bind three myc-like (USF) sites in the APEX promoter, in contrast to the APE promoter. The APEX and APE promoter had similar activity in Hela cells, but in mouse cells, the murine promoter had approximately 5-fold higher activity than did the human promoter. Both the APEX and APE promoters exhibited bidirectional activity in their cognate cells.
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PMID:Comparison of the promoters of the mouse (APEX) and human (APE) apurinic endonuclease genes. 950 86

Among the more frequent oxidative DNA injuries is the formation of abasic sites (AP sites) resulting from removal of purine or pyrimidine bases, estimated to occur at a rate of 1 x 10(4)/genome/24 h. A defect in DNA repair at this level could account for the accumulation of mutations and subsequent genome instability. We have identified missense mutations in the APE gene coding for a multifunctional DNA repair enzyme, AP endonuclease in eight of 11 patients with amyotrophic lateral sclerosis (ALS) and familial ALS. These mutations could affect the repair of abasic sites leading to the accumulation of mutations in neurons, resulting in their degeneration and death. Our findings implicate mutated AP endonuclease in the pathogenesis of ALS.
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PMID:Mutant AP endonuclease in patients with amyotrophic lateral sclerosis. 950 62

Human DNA polymerase and DNA ligase utilization for the repair of a major class of ionizing radiation-induced DNA lesion [DNA single-strand breaks containing 3'-phosphoglycolate (3'-PG)] was examined using a novel, chemically defined vector substrate containing a single, site-specific 3'-PG single-strand break lesion. In addition, the major human AP endonuclease, HAP1 (also known as APE1, APEX, Ref-1), was tested to determine if it was involved in initiating repair of 3'-PG-containing single-strand break lesions. DNA polymerase beta was found to be the primary polymerase responsible for nucleotide incorporation at the lesion site following excision of the 3'-PG blocking group. However, DNA polymerase delta/straightepsilon was also capable of nucleotide incorporation at the lesion site following 3'-PG excision. In addition, repair reactions catalyzed by DNA polymerase beta were found to be most effective in the presence of DNA ligase III, while those catalyzed by DNA polymerase delta/straightepsilon appeared to be more effective in the presence of DNA ligase I. Also, it was demonstrated that the repair initiating 3'-PG excision reaction was not dependent upon HAP1 activity, as judged by inhibition of HAP1 with neutralizing HAP1-specific polyclonal antibody.
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PMID:Determination of human DNA polymerase utilization for the repair of a model ionizing radiation-induced DNA strand break lesion in a defined vector substrate. 1032 34


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