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)

Analyses of cleavage ends of DNA fragments in apoptotic rat thymocytes induced by gamma-ray irradiation or by treatment with dexamethasone revealed that in both cases the fragments produced had 3'-hydroxyl (OH) and 5'-phosphoryl (P) ends of DNA chains. Rat thymocyte nuclei contained at least three endonuclease activities (deoxyribonucleases alpha, beta and gamma) that were able to cleave chromatin to mononucleosomal and oligonucleosomal fragments. The nuclei of apoptotic rat thymocytes induced by gamma-ray irradiation or dexamethasone retained considerable deoxyribonuclease gamma activity, but not alpha or beta deoxyribonuclease activity. During the induction of apoptosis, treatment with cycloheximide, which suppressed apoptosis, resulted in marked decreases of deoxyribonucleases alpha and beta activities. After release of cycloheximide inhibition, DNA fragmentation associated with apoptosis occurred in the cycloheximide-treated thymocyte nuclei, in which deoxyribonuclease gamma activity was only observed. The purified deoxyribonucleases alpha and beta were divalent cation-independent acidic endonucleases, which were separated on a CM5PW column by HPLC. The molecular masses of deoxyribonucleases alpha and beta were 28 kDa and 30 kDa, respectively, as determined by TSK G-2000SW gel-filtration HPLC, and both were 32 kDa in molecular mass as determined by SDS/PAGE. In contrast, deoxyribonuclease gamma, a neutral endonuclease, required both Ca2+ and Mg2+ for full activity and was inhibited by Zn2+. The molecular mass of deoxyribonuclease gamma was 31 kDa and 33 kDa when measured by gel filtration and SDS/PAGE, respectively. Under these optimal conditions, deoxyribonuclease gamma was shown to produce 3'-OH/5'-P ends of nucleosomal DNA fragments, while deoxyribonucleases alpha and beta both formed DNA fragments with 3'-P/5'-OH ends. The ends formed by cleavage with deoxyribonuclease gamma were the same as those produced in apoptotic rat thymocytes. On the basis of these results, it seems likely that deoxyribonuclease gamma is responsible for internucleosomal cleavage of chromatin during thymic apoptosis.
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PMID:Identification of an endonuclease responsible for apoptosis in rat thymocytes. 795 53

Three distinct endonucleases (DNase alpha, beta and gamma) were isolated from rat thymocyte nuclei. These three DNases differed in chromatographic behaviors and in apparent molecular masses. The cognate form of acidic DNases alpha and beta did not require divalent cations for their activities, whereas DNase gamma was a neutral endonuclease that required both Ca2+ and Mg2+ for full activity and was inhibited by Zn2+. These enzymes digested HeLa S3 cell nuclear chromatin to the nucleosomal fragments characteristic of apoptosis. Interestingly, apoptotic rat thymocyte nuclei induced by gamma-ray irradiation or glucocorticoid retained considerable activity of DNase gamma, whereas their activities of DNases alpha and beta were markedly reduced. These results indicate that in rat thymocytes DNase gamma is involved in DNA fragmentation during apoptosis.
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PMID:Multiple forms of nuclear deoxyribonuclease in rat thymocytes. 809 58

Apoptosis is a mechanism for eliminating unwanted cells from the cell community of multicellular organisms. Abnormalities in the regulation of apoptosis may play a part in the aetiology of cancer, autoimmune diseases, AIDS, degenerative nerve diseases and malformation. On of the hallmarks of apoptosis is the enzymatic cleavage of genomic DNA into nucleosomal oligomers. The identification of an endonuclease responsible for apoptosis might help to explain how this cell suicide is regulated and why DNA is cleaved. Here, we found that gamma type of DNase was retained in apoptotic rat thymocyte nuclei. The mode of DNA cleavage, 3'-hydroxyl (OH)/5'-phosphoryl (P) ends, by homogeneously purified DNase gamma (Mr = 33 kDa) and its Zn2+ sensitivity match those observed in apoptosis in thymocytes induced by irradiation or glucocorticoid treatment, indicating that this endonuclease is a central component of the thymic apoptosis machinery.
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PMID:[Apoptosis: its molecular mechanisms and biological roles]. 857 68

DNase gamma has been suggested to be an endonuclease responsible for thymic apoptosis in mammals. Using the frog, Xenopus laevis, we examined whether any hematopoietic cells other than thymocytes have DNase gamma activity. The activity gel assays and HeLa cell nuclear assays for DNase revealed that nuclei from red blood cells and cells in liver (an erythropoietic organ) contain DNase gamma-like activities (molecular mass of 38 and 36 kDa) indicated by their biochemical features (internucleosomal DNA cleavage, requirement of Ca2+ and Mg2+, and sensitivity to Zn2+). Distribution of these two (38 and 36 kDa) forms of enzyme was determined by cell fractionation analysis of liver cells: the 38 kDa form of enzyme was found in erythrocytes/erythroblasts and hepatocytes, whereas the 36 kDa form was in lymphocytes/macrophages. Interestingly, these two enzyme activities increased during metamorphic climax, at which time larval-type cells are converted to adult ones. It thus appears that these gamma-type DNases are involved in programmed cell death during metamorphosis.
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PMID:Occurrence of DNase gamma-like apoptotic endonucleases in hematopoietic cells in Xenopus laevis and their relation to metamorphosis. 907 Feb 68

We previously identified three distinct DNA endonucleases, DNases alpha, beta and gamma, present in rat thymocyte nuclei. On the basis of their enzymic and biochemical properties, gamma-type DNase was regarded as a candidate for the apoptotic endonuclease. Here we purified DNase gamma to apparent homogeneity from apoptotic rat thymocyte nuclei induced by X-irradiation and characterized its properties in detail. The purified DNase gamma exhibited one predominant protein band on SDS/PAGE and an endonuclease activity in a zymography with an estimated molecular mass of 33 kDa. The molecular mass of the native form determined by G2000SW gel-filtration HPLC was 30 kDa. Amino acid analysis showed that the amino acid composition of DNase gamma was similar to that of rat DNase I (molecular mass 32 kDa) but different with regard to alanine and lysine residues. The N-terminal amino acid sequence of DNase gamma was revealed to be not identical with that of rat DNase I. In accordance with previous studies, homogeneously purified DNase gamma requires both Ca2+ and Mg2+ for activity. This requirement could be partially supplied by Mn2+. Of the bivalent metal ions tested, Co2+, Ni2+, Cu2+ and Zn2+ inhibited DNase gamma activity. These bivalent cations also suppressed apoptotic DNA fragmentation in rat thymocytes irradiated by X-rays. The same order of inhibitory ability was observed for these bivalent metal ions in vivo (in intact cells) and in vitro, suggesting that the suppression of apoptotic DNA fragmentation at the cellular level is due to the inhibition of DNase gamma. DNase gamma activity was found to exist at high levels in spleen, lymph node, thymus, liver and kidney, but little was present in brain, heart or pancreas. On the basis of these findings, together with previous data, we conclude that DNase gamma is a novel DNase I-like endonuclease responsible for internucleosomal cleavage of chromatin during thymic apoptosis.
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PMID:Purification and properties of DNase gamma from apoptotic rat thymocytes. 930 16

An endonuclease named DNase gamma was purified to apparent homogeneity from rat splenocyte nuclei and its properties were characterized. We also determined the NH2-terminal and partial amino acid sequences of the proteolytic internal peptides. The molecular mass of gamma DNase was 33,000 daltons as determined by SDS-polyacrylamide gel electrophoresis. A native molecular mass of 30,000 was estimated by gel filtration. Purified DNase gamma is active in the presence of both Ca2+ and Mg2+ or Mn2+ alone and inhibited by Co2+, Ni2+, Cu2+, and especially Zn2+. Maximal activity was achieved at pH 7.2 in Mops-NaOH buffer. The sequence data on the NH2-terminal and seven internal peptides obtained by sequential digestions with Achromobacter protease I and endoproteinase Asp-N revealed that DNase gamma is a novel endonuclease that shows sequence homology with DNase I.
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PMID:Purification, characterization, and amino acid sequencing of DNase gamma from rat spleen. 932 79

An endonuclease named DNase gamma has been purified from the nuclei of apoptotic rat thymocytes [Shiokawa, Ohyama, Yamada and Tanuma (1997) Biochem. J. 326, 675-681]. Here we report the molecular cloning of a cDNA encoding a 35 kDa precursor protein for rat DNase gamma. A 1.6 kb mRNA coding for the DNase gamma precursor is detected at high levels in spleen, lymph nodes, thymus and liver. By using reverse transcriptase-mediated PCR, expression of DNase gamma mRNA is observed in kidney and testis but not in brain or heart. Analysis of recombinant DNase gamma reveals that full-length DNase gamma, including the N-terminal precursor, is an inactive proenzyme. The mature form of recombinant DNase gamma, from which the N-terminal precursor has been removed, has the same properties as purified DNase gamma: requirement for divalent cations, dependence on pH, sensitivity to Zn2+, and cleavage of chromosome DNA to nucleosomal units. In HeLa S3 cells stably transfected with the DNase gamma cDNA, exogenously introduced DNase gamma is activated by apoptotic stimuli; enhancement of DNA fragmentation, chromatin condensation and nuclear collapse are observed. These findings provide evidence for the involvement of DNase gamma in DNA fragmentation and nuclear structural changes during apoptosis.
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PMID:Molecular cloning and expression of a cDNA encoding an apoptotic endonuclease DNase gamma. 962 Aug 74

We describe here the characterization of the so far identified human DNase I family DNases, DNase I, DNase X, DNase gamma, and DNAS1L2. The DNase I family genes are found to be expressed with different tissue specificities and suggested to play unique physiological roles. All the recombinant DNases are shown to be Ca(2+)/Mg(2+)-dependent endonucleases and catalyze DNA hydrolysis to produce 3'-OH/5'-P ends. High activities for DNase I, DNase X, and DNase gamma are observed under neutral conditions, whereas DNAS1L2 shows its maximum activity at acidic pH. These enzymes have also some other peculiarities: different sensitivities to G-actin, aurintricarboxylic acid, and metal ions are observed. Using a transient expression system in HeLa S3 cells, the possible involvement of the DNases in apoptosis was examined. The ectopic expression of each DNase has no toxic effect on the host cells; however, extensive DNA fragmentation is observed only in DNase gamma-transfected cells after the induction of apoptosis. Furthermore, DNase gamma is revealed to be located at the perinuclear region in living cells, and to translocate into the nucleus during apoptosis. Our results demonstrate that DNase I, DNase X, DNase gamma, and DNAS1L2 have similar but unique endonuclease activities, and that among DNase I family DNases, DNase gamma is capable of producing apoptotic DNA fragmentation in mammalian cells.
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PMID:Characterization of human DNase I family endonucleases and activation of DNase gamma during apoptosis. 1114 Oct 64

Nucleosomal DNA fragmentation is detected in myoblasts only when apoptosis is induced under differentiating conditions. However, the molecular mechanisms and the DNase responsible for the differentiation-dependent apoptotic DNA laddering are poorly understood. Here we show that a Ca(2+)/Mg(2+)-dependent endonuclease, DNase gamma, is induced in C2C12 myoblasts during myogenic differentiation and catalyzes apoptotic DNA fragmentation in differentiating myoblasts. A Ca(2+)/Mg(2+)-dependent, Zn(2+)-sensitive endonuclease activity appears in C2C12 myoblasts during myogenic differentiation. The enzymatic properties of the inducible DNase were found to be quite similar to those of DNase I family of DNases. Reverse transcriptase-PCR analysis revealed that the induction of DNase gamma, a member of the DNase I family of DNases, is correlated with the appearance of inducible DNase activity. The induction of DNase gamma occurs simultaneously with myogenin induction but precedes the up-regulation of p21. A high level of DNase gamma expression was also detected in differentiated myotubes but not in skeletal muscle fibers in which DNase X is highly expressed. The role of DNase gamma in myoblast apoptosis was evaluated in the following experiments. Proliferating myoblasts acquire DNA ladder producing ability by the ectopic expression of DNase gamma, but not DNase X, suggesting that the expression level of DNase gamma is the determinant of the differentiation-dependent apoptotic DNA laddering observed in myoblasts. DNA fragmentation during differentiation-induced apoptosis is strongly suppressed by the antisense-mediated down-regulation of DNase gamma. Importantly, the extent of DNA laddering is well correlated with the level of endogenous DNase gamma activity. Our data demonstrate that DNase gamma is the endonuclease responsible for DNA fragmentation in apoptosis associated with myogenic differentiation.
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PMID:Involvement of DNase gamma in apoptosis associated with myogenic differentiation of C2C12 cells. 1205 Jan 66

We recently found that two apoptotic DNase gamma-like endonucleases (36 and 38 kDa DNases) were present in Xenopus laevis larval and adult liver cell nuclei and that their activities increased in metamorphic climax. Here, we purified the main DNase gamma-like endonuclease from Xenopus laevis liver cell nuclei and characterized its physical and enzymatic properties in detail. The molecular mass of Xenopus liver nuclear endonuclease was 38,000 daltons as determined by SDS-polyacrylamide gel electrophoresis. A native molecular mass of 35,000 was estimated by gel filtration. The purified Xenopus liver endonuclease was a neutral one and required both Ca2+ and Mg2+ for DNase activity. Unlike the mammalian DNase gamma, the Ca2+/Mg2+ requirement could not be supplied by Mn2+. The inhibition profiles by aurintricarboxylic acid, sodium citrate and divalent metal ions such as Co2+, Ni2+, Cu2+ and Zn2+ were similar to those of mammalian DNase gamma. These results suggest that this endonuclease is a Xenopus laevis homolog of the mammalian apoptotic endonuclease DNase gamma.
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PMID:Purification and characterization of a DNase gamma-like endonuclease from Xenopus laevis liver. 1464 95


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