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

All but one of the six free sulfhydryl groups of chick brain actin depolymerizing factor (ADF) are protected from modification when ADF forms a 1:1 complex with actin. This exposed sulfhydryl can be cross-linked to cys 374 of actin with N,N'-phenylenedimaleimide. The cross-linked complex inhibits the hydrolytic activity of pancreatic deoxyribonuclease (DNase I) to an identical extent as both the untreated complex and an equivalent amount of free actin. These data indicate that ADF binds to actin at a site which does not overlap with the DNase I binding site.
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PMID:Inhibition of deoxyribonuclease I activity by actin covalently cross-linked to chick brain actin depolymerizing factor through exposed sulfhydryls. 245 26

In a simple eukaryote Physarum polycephalum about 13% of the genome is transcribed into abundant cytoplasmic RNA as shown by S1 nuclease digestion of DNA-RNA hybrids. Mild digestion of isolated Physarum nuclei with DNase I liberates a fraction of chromatin 3.5-fold enriched in sequences hybridizing by Physarum poly(A)+ RNA. This fraction is similarly enriched in histone H4 and actin genes known to be actively transcribed in Physarum. High content (about 45%) of actively transcribed sequences in DNase-I-released fraction of Physarum chromatin makes it particularly well suited for studying the structural basis of transcriptional activation in eukaryotes.
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PMID:Transcriptionally active chromatin can be selectively released by DNase I from Physarum polycephalum genome. 246 74

To clarify the relationship between changes in serum pancreatic enzymes and pathological changes in pancreatic parenchyma, this study was performed by using rat models with acute pancreatitis. The models were rats with edematous and necrotizing pancreatitis. Amylase, lipase, ribonuclease (RNase), and deoxyribonuclease (DNase I, II) in the serum were determined for 48 h after the development of pancreatitis. Amylase and lipase levels rose directly in both pancreatitis groups. These enzymes in the necrotizing pancreatitis group were higher than those in the edematous pancreatitis group, but there was no significant difference. RNase levels also rose markedly, but there was no obvious difference between either of the pancreatitis groups. On the other hand, DNase levels were high in the necrotizing pancreatitis group but low in the edematous pancreatitis group, with significant differences between the two groups, especially in the DNase II levels over a 36-h period (p less than 0.05-0.01). Therefore, these results suggest that serum DNase levels reveal the necrotizing changes in pancreatic parenchyma.
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PMID:Relationship between pancreatic enzymes and pathological changes in the pancreas in acute pancreatitis. The significance of determination of serum deoxyribonuclease. 247 54

The activity of bleomycin to break the strand of deoxyribonucleic acid (DNA) in the presence of 2-hydroxy-1-ethanethiol (2-mercaptoethanol) was enhanced by ultraviolet (UV) irradiation. Photo-activated bleomycin stimulated the action of deoxyribonuclease I (DNase I) to degrade DNA and the DNA synthesis by DNA polymerase I with DNase I. On the other hand, although UV-irradiated bleomycin scarcely broke the DNA strand in the presence of 1,2-benzenediol (catechol), it stimulated the action of DNase I to degrade DNA in the presence of catechol. In accordance with the inhibition by catechol, when DNA treated with UV-irradiated bleomycin in the presence of catechol was employed as a primer for the DNA synthesis, the incorporation of precursor into the acid-insoluble fraction by DNA polymerase I with exonuclease III was reduced to about one-half of the incorporation into DNA treated with unirradiated bleomycin. These findings suggest that the ability of bleomycin to bind to double-helical DNA forming regions sensitive to DNase I was increased by an appropriate dose of UV irradiation and that catechol inhibited the activity of the UV-irradiated bleomycin to break the DNA strand rather than to bind to DNA.
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PMID:Effects of photo-activated bleomycin on deoxyribonuclease I, exonuclease III and deoxyribonucleic acid polymerase I reactions. 247 48

As in tumors with c-myc chromosomal translocations, c-myc retrovirus-induced monocyte tumors constitutively express an activated form of c-myc (the proviral gene), whereas the normal endogenous c-myc genes are transcriptionally silent. Treatment of these retrovirus-induced tumor cells with a number of bioactive chemicals and growth factors that are known to induce c-myc expression in cells of the monocyte lineage failed to induce the endogenous c-myc gene. In contrast, the same treatments induced the c-fos gene in both tumors and a control macrophage line. To investigate c-myc suppression further, a normal copy of the human c-myc gene was introduced into tumor and control cell lines by using a retrovirus with self-inactivating long terminal repeats. This transduced normal gene was expressed at equivalent levels in all cells, regardless of the state of endogenous c-myc gene expression, and was strongly induced by agents that induce the normal gene in the control cells. These results indicate that the signal transduction pathways that normally activate the c-myc gene are functional in myc-induced tumor cells and suggest that endogenous c-myc is actively suppressed. An examination of the c-myc locus itself showed that the lack of transcriptional activity correlated with the absence of several prominent DNase I-hypersensitive sites in the 5'-flanking region of the gene but without loss of general DNase sensitivity. Furthermore, analysis of 22 methylation-sensitive restriction enzyme sites in the 5'-flanking region, first exon, and first intron indicated that the silent c-myc genes remained in the same unmethylated state as did actively expressed genes. Thus, c-myc suppression does not appear to result from the most frequently described mechanisms of gene inactivation.
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PMID:Germ line c-myc is not down-regulated by loss or exclusion of activating factors in myc-induced macrophage tumors. 247 87

The male hybrid B6C3F1 mouse exhibits a 30% spontaneous hepatoma incidence, whereas the paternal C3H/He strain and the maternal C57BL/6 strain exhibit a 60% and a negligible incidence, respectively. In addition, both male and female B6C3F1 mice are extremely sensitive to chemical induction of hepatocarcinogenesis. The Ha-ras, Ki-ras, and myc oncogenes have been implicated in a variety of solid tumors. Specifically, Ha- and, less frequently, Ki-ras have been reported to be activated in B6C3F1 mouse liver tumors. The objective of this study was to examine a possible point of transcriptional control of Ha-ras, Ki-ras, and myc in all three mouse strains, our hypothesis being that these oncogenes may be primed for expression in the nascent liver of those strains exhibiting a high spontaneous hepatoma incidence. A positive correlation has been established between gene expression and the presence of DNAase I hypersensitive sites. DNase I hypersensitive sites were observed in the Ha-ras and myc oncogenes in the three mouse strains. However, Ha-ras appears to possess an additional site in B6C3F1 and C3H/He as compared to C57BL/6. Similarly, the Ki-ras oncogene exhibited a DNase I hypersensitive site only in B6C3F1 and C3H/He mouse liver. These results indicate that the hepatoma-prone strains (B6C3F1 and C3H/He) may have a greater potential for Ha- and Ki-ras expression than does the non-hepatoma-prone strain (C57BL/6).
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PMID:Differential DNase I hypersensitivity of ras oncogenes in B6C3F1, C3H/He, and C57BL/6 mouse liver. 248 56

The stoichiometric actin--DNase-I complex was used to study the actin--nucleotide and actin--divalent-cation interactions and its ATPase activity in the presence of MgCl2 and cytochalasin D. Treatment of actin--DNase-I complex with 1 mM EDTA results in almost complete restoration of its otherwise inhibited DNase I activity, although the complex does not dissociate, as verified by size-exclusion chromatography. This effect is due to a loss of actin-bound nucleotide but is prevented by the presence of 0.1-0.5 mM ATP, ADP and certain ATP analogues. In this case no increase in DNase I activity occurs, even in the presence of EDTA. At high salt concentrations and in the presence of Mg2+ ('physiological conditions') the association rate constants for ATP, ADP and epsilon ATP (1,N6-ethenoadenosine 5'-triphosphate) and the dissociation rate constant for epsilon ATP were determined. Both the on and off rates were found to be reduced by a factor of about 10 when compared to uncomplexed actin. Thus the binding constant of epsilon ATP to actin is almost unaltered after complexing to DNase I (2.16 x 10(8) M-1). Titrating the increase in DNase I activity of the actin--DNase I complex against nucleotide concentration in the presence of EDTA, the association constant of ATP to the cation-free form of actin--DNase I complex was found to be 5 x 10(3) M-1, which is many orders of magnitude lower than in the presence of divalent metal ions. The binding constant of Ca2+ to the high-affinity metal-binding site of actin was found not to be altered when complexed to DNase I, although the rate of Ca2+ release decreases by a factor of 8 after actin binding to DNase I. The rate of denaturation of nucleotide-free and metal-ion-free actin--DNase I complex was found to be reduced by a factor of about 15. The ATPase activity of the complex is stimulated by addition of Mg2+ and even more effectively by cytochalasin D, proving that this drug is able to interact with monomeric actin.
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PMID:The complex of actin and deoxyribonuclease I as a model system to study the interactions of nucleotides, cations and cytochalasin D with monomeric actin. 250 Mar 40

After exposure to ligand at 0-4 degrees C, estrogen receptors from mouse uteri characteristically eluted between thyroglobulin (Mr 669,000) and ferritin (Mr 443,000) during size-exclusion HPLC. However, when preparations were warmed with ligand under mild activating conditions, most or all of the receptor was observed as a much larger complex, which eluted between dextran blue 2000 and thyroglobulin. Formation of the large complex required ligand, was inhibited by molybdate, and occurred even in 0.4 M KCl. Slower ligand dissociation characterized the large complex, indicating that activated receptors were included preferentially. This large complex did not form when charged cytosols were aged, concentrated, or precipitated, indicating that formation was not the result of random aggregation. After exposure to conditions commonly used for activation (25 degrees C, 60 min), most receptor existed as a very large, monodisperse complex of finite size, predicting an ordered structure for these large complexes that should be useful for defining the types of proteins which can interact with estrogen receptors. Formation of the large complex was not impeded or disrupted by EDTA, RNase, DNase I, thiourea, or mercaptoethanol; however, the capacity to form this large complex was not demonstrated by preparations that had been exposed to trypsin or by the small receptor forms obtained after salt extraction. Proteolytic sensitivity and lack of sensitivity to RNase or DNase indicate that interactions between receptors and other proteins are involved in peak A formation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intermolecular engagement of estrogen receptors indicated by the formation of a high molecular weight complex during activation. 251 8

Two DNase I-hypersensitive regions were identified downstream of the TCR gene constant region. One of these regions is located at the site of a putative enhancer element and was observed only in T cell lines and not in cell lines derived from other tissues. The other DNase-hypersensitive region was also detected only in T cell lines but only in those expressing TCR-beta RNA. Thus, the first region is probably tissue specific, while the second region is probably tissue and stage specific. The DNA sequence of the second DNase I-hypersensitive region revealed several stretches of nucleotides that are characteristic of consensus sequences for regulatory elements. These results, together with the observations in transgenic mice that indicate a requirement for two distinct regions for optimal TCR gene expression, suggest the presence of at least two regulatory regions downstream of the C-beta-2 region; one is an enhancer region and the other is a transcriptionally related regulatory region. The tissue/stage specificity of these DNase I-hypersensitive regions supports the notion that changes in chromatin structure control tissue-specific gene expression.
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PMID:T cell receptor beta gene has two downstream DNase I hypersensitive regions. Possible mechanisms of tissue- and stage-specific gene regulation. 252 73

A differential Giemsa staining between sister chromatids was obtained by treating chromosomes replicated twice in medium containing 5-bromodeoxyuridine (BrdU) with Hoechst 33258 plus black light at 55 degrees C (HB pretreatment) and deoxyribonuclease (DNase) I, II, or micrococcal nuclease. In this staining pattern the BrdU bifilarly substituted chromatids were darkly and the unifilarly substituted chromatids lightly stained. This staining pattern was obtained only by staining the HB-DNase I-treated chromosomes with Giemsa and methylene blue, not by several other dyes tested. Relatively more DNA labelling was removed from the non-BrdU-substituted than the BrdU-substituted chromosomes, when the HB-pretreated chromosomes were digested with DNase I. But the protein labelling was not removed appreciably in the same treatment. The differential DNase I sensitivity between the non-BrdU-substituted and BrdU-substituted chromosomes disappeared when the HB-pretreated chromosomes were incubated with proteinase K before The DNase I digestion. Moreover, no differential DNase I sensitivity was found between the HB-pretreated isolated DNA containing and not containing BrdU. We propose that during the HB pretreatment, more DNA-protein cross-linkings are induced in BrdU bifilarly substituted than the unifilarly substituted chromatids. This structure protects the chromosomal DNA against the DNase I digestion. Thus, a reverse differential Giemsa staining between sister chromatids is obtained by the HB-DNase I treatment.
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PMID:Reverse differential staining of sister chromatids induced by Hoechst plus black light and endonuclease. 257 33


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