Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.21.1 (DNase)
 7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A nuclear antigen associated with cell proliferation (proliferating cell nuclear antigen [PCNA]) and blast transformation is recognized by autoantibodies in the sera of some patients with systemic lupus erythematosus. Using this autoantibody as a reagent, PCNA was purified 120-fold by ammonium sulfate fractionation, DEAE chromatography, and Sephadex G200 gel filtration. The antigenicity of PCNA was sensitive to trypsin but resistant to ribonuclease and deoxyribonuclease, suggesting that the antigenic determinant resided in protein and not nucleic acids. PCNA was inactivated at 56 degrees C for 30 min. Isoelectrophoretic focusing showed that the pI was 4.8. Analysis of immunoprecipitates on polyacrylamide gels showed the presence of IgG heavy and light chains and a single polypeptide band of 33,000 mol wt. This polypeptide band was the reactive antigen in immunoblotting (Western transfer) assays.
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PMID:Characterization of proliferating cell nuclear antigen recognized by autoantibodies in lupus sera. 614 19

We have identified and purified a multiprotein form of DNA polymerase from the murine mammary carcinoma cell line (FM3A) using a series of centrifugation, polyethylene glycol precipitation, and ion-exchange chromatography steps. Proteins and enzymatic activities associated with this mouse cell multiprotein form of DNA polymerase include the DNA polymerases alpha and delta, DNA primase, proliferating cell nuclear antigen (PCNA), DNA ligase I, DNA helicase, and DNA topoisomerases I and II. The sedimentation coefficient of the multiprotein form of DNA polymerase is 17S, as determined by sucrose density gradient analysis. The integrity of the murine cell multiprotein form of DNA polymerase is maintained after treatment with detergents, salt, RNase, DNase, and after chromatography on DE52-cellulose, suggesting that the association of the proteins with one another is independent of nonspecific interaction with other cellular macromolecular components. Most importantly, we have demonstrated that this complex of proteins is fully competent to replicate polyomavirus DNA in vitro. This result implies that all of the cellular activities required for large T-antigen dependent in vitro polyomavirus DNA synthesis are present within the isolated 17S multiprotein form of the mouse cell DNA replication activities. A model is proposed to represent the mammalian Multiprotein DNA Replication Complex (MRC) based on the fractionation and chromatographic profiles of the individual proteins found to co-purify with the complex.
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PMID:A 17S multiprotein form of murine cell DNA polymerase mediates polyomavirus DNA replication in vitro. 812 85

In eukaryotic cells, a 5' flap DNA endonuclease activity and a ds DNA 5'-exonuclease activity exist within a single enzyme called FEN-1 [flap endo-nuclease and 5(five)'-exo-nuclease]. This 42 kDa endo-/exonuclease, FEN-1, is highly homologous to human XP-G, Saccharomyces cerevisiae RAD2 and S.cerevisiae RTH1. These structure-specific nucleases recognize and cleave a branched DNA structure called a DNA flap, and its derivative called a pseudo Y-structure. FEN-1 is essential for lagging strand DNA synthesis in Okazaki fragment joining. FEN-1 also appears to be important in mismatch repair. Here we find that human PCNA, the processivity factor for eukaryotic polymerases, physically associates with human FEN-1 and stimulates its endonucleolytic activity at branched DNA structures and its exonucleolytic activity at nick and gap structures. Structural requirements for FEN-1 and PCNA loading provide an interesting picture of this stimulation. PCNA loads on to substrates at double-stranded DNA ends. In contrast, FEN-1 requires a free single-stranded 5' terminus and appears to load by tracking along the single-stranded DNA branch. These physical constraints define the range of DNA replication, recombination and repair processes in which this family of structure-specific nucleases participate. A model explaining the exonucleolytic activity of FEN-1 in terms of its endonucleolytic activity is proposed based on these observations.
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PMID:Processing of branched DNA intermediates by a complex of human FEN-1 and PCNA. 866 33

To clarify the effect of aging on rat liver regeneration, we compared proliferating cell nuclear antigen (PCNA) levels in control and regenerating livers from young and aged rats 48 h after partial hepatectomy. The nucleoplasm and cytoplasm from regenerating livers of 2-month and 24 month-old rats were fractionated by phosphocellulose column chromatography, aliquots of fractions were transferred to nitrocellulose filters and the amounts of PCNA in each fraction were measured by an immunostaining method. Two forms of PCNA, L type (eluted at low concentrations of KC1) and H type (eluted at high KC1 concentrations) were observed in the nucleoplasm from both control and regenerating young rat liver. On the other hand, the cytoplasm contained P type (eluted in the pass-through fraction), L type and H type PCNA. In control liver from aged rats, three types of PCNA in the cytoplasm and two types in the nucleoplasm were present at decreased levels. In regenerating liver from young rats, the increases in L type in the cytoplasm and H type in the nucleoplasm were remarkable. However, none of the three PCNA types increased significantly during liver regeneration in aged rats. Treatment with DNase resulted in the disappearance of the H type with a concomitant increase in the P and L types. These results suggest that the H type is a complex form consisting of the P and L types of PCNA and DNA. These results suggest that the increase in the L type in the cytoplasm reflects newly synthesized PCNA production for cellular proliferation and that the increase in the H type in the nucleoplasm is a reflection of binding to DNA and the fundamental role of PCNA itself in liver regeneration in young rats. On the other hand, there was little increase in any of the three types in regenerating liver from 24-month-old rats. Thus, PCNA content may be closely related to the decrease in the rate of cellular proliferation in aged animals.
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PMID:Age-related changes in proliferating cell nuclear antigen levels. 903 55

While the elimination of hepatitis B virus (HBV) is a common phenomenon at the end of the acute phase of disease, the persistence of HBV is characteristic for chronic hepatitis (CHB). Recent evidence indicates that the elimination of HBV is achieved by FAS/FAS-L induced apoptosis of infected hepatocytes. The aim of this study was to test the hypothesis that HBV persistence in the hepatocytes of CHB patients is due to the delayed onset of apoptosis caused by altered FAS/FAS-L interactions between lymphocytes and hepatocytes. The expression of FAS, FAS-L, BAX, BCL-2, ICE and PCNA in the liver biopsies of 55 patients (14 HBsAg positive, 20 patients with alcoholic hepatopathy, 21 patients with other hepatopathies) was tested by immunohistochemistry. Apoptosis of hepatocytes was evaluated by morphological as well as by TUNEL method. The results were correlated with a grading/staging score and analysed statistically using a one way analysis of variance and the Duncan test. Significantly highernumbers of BAX positive hepatocytes were observed in HBsAg positive patients when compared to control groups. Similarly, both BAX and FAS positive lymphocytes were more frequent in HBsAg positive patients. FAS-L positive lymphocytes and hepatocytes were numerous in all patient groups. Increased numbers of BAX positive hepatocytes in CHB may reflect the increased readiness of these cells to undergo apoptosis. However, the increased numbers of both BAX and FAS positive lymphocytes in CHB suggest that these cells may be particularly sensitive to FAS-L mediated apoptosis potentially resulting in lowered viability of these lymphocytes. This may explain, at least in part, the defective removal of virus-infected cells in chronic hepatitis. However, we cannot rule out the possibility that survival of hepatocytes during CHB may be due to other mechanisms such as defects in apoptosis activation triggered by CD40, defects involving DNase and/or other caspases downstream in the apoptotic cascade within these cells, or to defects in CTL function.
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PMID:Apoptosis-related proteins, BCL-2, BAX, FAS, FAS-L and PCNA in liver biopsies of patients with chronic hepatitis B virus infection. 1093 89

The oligomeric "sliding clamp" processivity factors, such as PCNA, are thought to rely on a loose, topological association with DNA to slide freely along dsDNA. Unlike PCNA, the processivity subunit of the herpes simplex virus DNA polymerase, UL42, is a monomer and has an intrinsic affinity for dsDNA that is remarkably high for a sequence-independent DNA binding protein. Using a DNase footprinting assay, we demonstrate that UL42 translocates with the catalytic subunit of the polymerase during chain elongation. In addition, footprinting and electrophoretic mobility shift assays show that, despite its tight DNA binding, UL42 is capable of linear diffusion on DNA at a rate of between 17 and 47 bp/s. Our results thus suggest that, despite profound biochemical differences with the sliding clamps, UL42 can freely slide downstream with the catalytic subunit during DNA replication.
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PMID:Linear diffusion on DNA despite high-affinity binding by a DNA polymerase processivity factor. 1168 25

The sequential organisation of replication foci during S phase in onion ( Allium cepa) and their relationship to the nuclear matrix were investigated. To discern their structural features and temporal firing sequence, immunodetection of 5-bromo-2'-deoxyuridine (BrdU) was carried out after in vivo feeding in synchronised cells released from a 14-h-long hydroxyurea block. Replication foci consisted of small replication granules, called replisomes, which clustered together. Analysis of synchronous binucleate cells that maintained in their two nuclei the specular symmetry of distribution of sister chromosomes in anaphase, showed that replication starts in small replication foci at the telomeric pole (pattern I), though the telomeres themselves formed large foci that were late-replicating. The rDNA replication foci (pattern II) also become replicated in early S phase. Replication of large foci, including the heterochromatin (IV), occurred in late S phase and finished at the centromeric nuclear pole (pattern V). Labelling of proliferating cell nuclear antigen (PCNA) in nuclear matrices, prepared from S-phase nuclei after extensive DNase digestion, demonstrated that replication foci were always stably anchored to the nuclear matrix. Thus, association with the nucleoskeleton is not exclusively mediated by the replicating or nascent DNA. The overlapping of patterns I, II and III in the nuclear matrix, in contrast to the results of BrdU localisation in nuclei, suggests that PCNA becomes associated with the nuclear matrix before the replication foci are operative, and remains bound during replication.
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PMID:Dynamics of replication foci and nuclear matrix during S phase in Allium cepa L. cells. 1202 68

Endonuclease G (EndoG) is a mitochondrial enzyme that becomes an apoptotic nuclease when released from the mitochondrial intermembrane space. EndoG will digest either DNA or RNA, but at physiological ionic strength, RNA is a much more favorable substrate as compared to chromatin. This indicates that EndoG's major in vivo function(s) may be: (i) an apoptotic RNase, and/or (ii) an apoptotic DNase in the presence of additional co-activators. In the present study we have searched for factors that modulate the activity of human EndoG on DNA substrates. We demonstrate that EndoG forms complexes with AIF and FEN-1 but not with PCNA. Interestingly, heat shock proteins 70 interact with EndoG and are involved in the regulation of its activity. Purified Hsp70 prevented stimulation of EndoG DNase activity by other nuclear factors in the ATP-dependent manner.
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PMID:Regulation of the human apoptotic DNase/RNase endonuclease G: involvement of Hsp70 and ATP. 1613 72

The RING finger protein TRAIP protects genome integrity and its mutation causes Seckel syndrome. TRAIP encodes a nucleolar protein that migrates to UV-induced DNA lesions via a direct interaction with the DNA replication clamp PCNA. Thus far, mechanistically how UV mobilizes TRAIP from the nucleoli remains unknown. We found that PCNA binding is dispensable for the nucleolus-nucleoplasm shuttling of TRAIP following cell exposure to UV irradiation, and that its redistribution did not rely on the master DNA damage kinases ATM and ATR. Interestingly, I-PpoI-induced ribosomal DNA damage led to TRAIP exclusion from the nucleoli, raising the possibility that active ribosomal DNA transcription may underlie TRAIP retention in the nuclear sub-compartments. Accordingly, chemical inhibition of RNA polymerase I activity led to TRAIP diffusion into the nucleoplasm, and was coupled with marked reduction of DNA/RNA hybrids in the nucleoli, suggesting that TRAIP may be sequestered via binding to nucleic acid structures in the nucleoli. Consistently, cell pre-treatment with DNase/RNase effectively released TRAIP from the nucleoli. Taken together, our study defines a bipartite mechanism that drives TRAIP trafficking in response to UV damage, and highlights the nucleolus as a stress sensor that contributes to orchestrating DNA damage responses.
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PMID:Nucleolar residence of the seckel syndrome protein TRAIP is coupled to ribosomal DNA transcription. 3016 63