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)

Methylation and DNase I-hypersensitive sites of the myeloperoxidase gene in human myeloid leukemia HL-60 cells were studied by Southern blot hybridization using the myeloperoxidase gene probes. Digestion of DNA with a methylation-sensitive restriction endonuclease indicated that a CpG in the CCGG sequence located 3.53 kbp upstream of the myeloperoxidase gene was unmethylated in HL-60 cells expressing the gene, whereas it was methylated in K562 cells and human placenta not expressing the gene. The site in HL-60 cells remained unmethylated after retinoic acid- or 12-O-tetradecanoyl-phorbol-13-acetate-induced differentiation that arrests myeloperoxidase synthesis. Digestion of isolated nuclei with various amounts of DNase I indicated that four DNase I-hypersensitive sites were in an upstream region of the myeloperoxidase gene in HL-60 cells and three sites were within the gene. In retinoic acid-induced cells, the bands of the hypersensitive site near the 5' side of the gene and that in the first intron became weak, while that of the site in the fifth intron became strong. The bands of these hypersensitive sites were weak in K562 cells. The implications of these changes in tissue-specific expression and developmental down-regulation of the myeloperoxidase gene are discussed.
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PMID:Undermethylation and DNase I hypersensitivity of myeloperoxidase gene in HL-60 cells before and after differentiation. 130 85

Two human erythroleukemia cell lines, HEL and K562, express transglutaminase activity. The enzyme was identified as a tissue transglutaminase following chromatographic purification. All-trans-retinoic acid (10 microM) stimulated differentiation in HEL cells as judged by a 4-fold increase in hemoglobin content and a reduction in cell proliferation. The transglutaminase activity increased 9-fold. This increase in transglutaminase was the result of a pretranslational regulation of the gene as revealed by Northern blot analysis of mRNA. These changes were not a result of cell apoptosis, since parallel DNA degradation catalyzed by a Ca2(+)-dependent endonuclease could not be demonstrated. The K562 cells, in contrast, showed no transglutaminase induction following exposure to retinoic acid and displayed no changes in maturation markers or cell growth.
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PMID:Differential expression of transglutaminase in human erythroleukemia cells in response to retinoic acid. 197 50

The human promyelocytic HL-60 cell line can be induced to differentiate to neutrophil-like cells in response to a variety of chemical stimuli. We have found that retinoic acid-treatment of HL-60 cells over a period of 6-8 days resulted in a progressive increase in the proportion of cells with mature neutrophil morphologies and was closely followed by an increase in the proportion of cells exhibiting the morphological characteristics of apoptosis, the non-pathological mode of cell death. Using Percoll step-density gradients we have demonstrated a marked increase in the buoyant density of these cells and have used this density difference to obtain enriched fractions of cells for more detailed study. Degradation of the nuclear DNA of these cells into integer multiples of about 200 base pairs, indicative of endogenous endonuclease activation a major characteristic of programmed cell death, was also demonstrated. From these observations we conclude that the mode of cell death in cultures of terminally differentiated HL-60 cells is that of apoptosis. These results parallel those of a recent report which has shown apoptosis to be the mode of cell death of ageing peripheral blood neutrophils. Because of this, we believe that our observations further validate the use of the HL-60 cell line as a model system for the study of human granulopoiesis in vitro and further, that this model system may be useful for gaining insight into the underlying mechanisms involved in apoptosis.
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PMID:HL-60 cells induced to differentiate towards neutrophils subsequently die via apoptosis. 231 49

To study the molecular basis for lack of expression of the simian virus 40 (SV40) early region genes in murine teratocarcinoma-derived stem cells, we introduced a recombinant plasmid consisting of pBR322 linked to the herpes simplex virus type 1 thymidine kinase gene and SV40 genome into thymidine kinase-deficient F9 stem cells. The resulting stem cell clone, 12-1, and a retinoic acid-induced differentiated daughter cell clone, 12-1a, each contain one copy per cell of the entire recombinant plasmid integrated into the cellular genome through a site on the pBR322 genome. Restriction endonuclease analyses indicate that there is no difference in integration site or organization of the three component parts of the plasmid genome within cellular DNA of stem and differentiated cells; yet the differentiated cells, 12-1a, express SV40 large tumor antigen whereas the stem cells, 12-1, do not. Both stem and differentiated cells produce two size classes of polyadenylylated RNA, 2900 and 2600 bases in length, homologous to the early region of the SV40 genome, detectable by RNA blotting analysis. S1 nuclease analysis of the SV40 transcripts present in stem and differentiated cells indicate that the SV40 mRNAs were identically spliced in the two cell types, in a manner consistent with that observed for spliced large and small tumor antigen mRNAs in SV40-infected monkey kidney cells. Thus, the failure of 12-1 teratocarcinoma stem cells, containing an integrated SV40 genome, to express SV40 tumor antigen is not due to a lack of transcription of the SV40 early region or to an inability to splice primary transcripts.
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PMID:Transcription of the simian virus 40 genome in DNA-transformed murine teratocarcinoma stem cells. 627 68

The beta-thymosins are a family of < 5kDa (MW), mostly acidic, proteins which were originally defined in the immune system. Recently, specific members of this family of cytoplasmic polypeptides, namely beta-4 and beta-10, were shown to bind monomeric G-actin both in vitro and in vivo. Whilst many aspects of programmed cell death or 'apoptosis' remain to be defined, the Ca2+/Mg(2+)-dependent endonuclease, DNase I does feature in this process. Monomeric G-actin binds to and inhibits the DNA-degrading activity of DNase I. Given that the intracellular abundance of thymosins beta-4 and beta-10 is related to cell division and differentiation and that anticancer/morphogenic agents such as retinoic acid (RA) and cyclic AMP modulate expression of their respective genes, it is possible that these G-actin sequestering proteins play significant roles in apoptosis perhaps mediated via DNase I.
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PMID:Molecular interactions between G-actin, DNase I and the beta-thymosins in apoptosis: a hypothesis. 781 61

Acute promyelocytic leukemia (APML) almost always involves a chromosomal translocation t(15:17) that results in the fusion of the retinoic acid receptor alpha (RAR alpha) gene with a transcription factor gene called PML. Several cases of APML with t(11;17) have recently been described, involving fusion of the RAR alpha gene with a new zinc finger gene named PLZF. We report here a second non-classical translocation, t(5;17), with a rearranged RAR alpha gene in a child with APML. Based on restriction endonuclease analysis, the rearrangement of RAR alpha occurred within the second intron, the common breakpoint site for t(15;17). The leukemic cells in the bone marrow aspirate were a mixture of hypergranular and hypogranular bilobed promyelocytes. Although less than 1% abnormal promyelocytes were identified after induction therapy, cytogenetics revealed persistent t(5;17). Therefore, the child was treated with all-trans-retinoic acid (ATRA). There was no disease progression, and one marrow was interpreted as remission, with confirmation by cytogenetics which failed to reveal the translocation. However, disease reoccurred shortly after completion of ATRA. This poor response to ATRA may be an additional characteristic associated with non-classical translocations in APML. The identification of a second variant translocation involving the RAR alpha gene in APML suggests yet another RAR alpha rearrangement related to neoplastic myelopoiesis.
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PMID:A non-classical translocation involving 17q12 (retinoic acid receptor alpha) in acute promyelocytic leukemia (APML) with atypical features. 805 72

Sequence analysis of the retinoic acid receptor-alpha (RAR alpha) gene from a subline of HL-60 cells (RA-res) stably resistant to all-trans retinoic acid (RA) disclosed a single-base change in codon number 411, the same C to T transition previously reported in an independently selected HL-60 RA resistant clone by Robertson et al (Blood 80:1885, 1992). This mutation eliminates a FokI restriction endonuclease site. Using primers framing this mutation in exon 9 of the RAR alpha gene, we showed that polymerase chain reaction products amplified from either mRNA or genomic DNA templates from the RA-res subline were completely resistant to FokI digestion whereas those from wild-type (wt) HL-60 cells could be digested to completion. The lack of a normal allele in the RA-res cells was confirmed by mixing experiments and hybridization analyses. Southern blot analysis of DNA from the RA-res and wt cells versus control placental DNA indicated that the RAR alpha gene is not haploid. The independent isolation of the same RAR alpha mutation in different laboratories suggests either that the mutation exits in a small subpopulation in the wt line or that this is a mutational "hot spot." Furthermore, the results indicate that if a dominant negative mode of resistance is involved in the RA-res subline, this must involve interference with the function of heterologous receptor proteins such as the retinoid X receptors. The lack of any normal RAR alpha in this subline may facilitate studies of the mode of action of retinoids.
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PMID:Retinoic acid-resistant HL-60 cells exclusively contain mutant retinoic acid receptor-alpha. 819 65

DNA fragmentation was evaluated in three instances of programmed cell death, interdigital cell death in embryonic mouse limbs, and metamorphic death of both the labial glands and intersegmental muscle in the tobacco hornworm Manduca sexta. In the mouse, we evaluated both developmental cell death and expanded-range cell death induced by retinoic acid. The status of DNA was examined in several ways. Nuclei were examined by electron microscopy and Feulgen staining. Quantitative assessment of total DNA content in Feulgen-stained degenerating nuclei was made for the gland. In the labial gland, DNA content does not drop during the early phases of cell death; nor is an endonucleolytic ladder seen when DNA was examined by ethidium bromide staining or prelabeling with [3H]thymidine. Only by using end labeling of DNA could we detect DNA fragmentation at a very late stage in cell death, day 4 of the collapse of the gland. In contrast, WEHI 7.1 lymphoma cells display an early and extensive ladder after treatment with glucocorticoids. In mouse limb, for which cell death follows a more classic apoptotic morphology, a ladder is likewise not seen. We conclude that activation of an endonuclease is neither a trigger nor a necessary or defining component of the early phases of developmental programmed cell death, and that reported failure by others to find such a ladder may depend on limitations in the system that is under investigation.
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PMID:Delayed internucleosomal DNA fragmentation in programmed cell death. 846 89

Genomic methylation patterns of Dunning R-3327 cell lines anaplastic tumor-1 (AT-1), anaplastic tumor-3 (AT-3), metastasis-lymph and lung (Mat-LyLu) and metastasis-lung (Mat-Lu), and Mat-LyLu cells treated with difluoromethylornithine (DFMO), and retinoic acid (RA) have been analyzed. Each cell line was digested with HpaII and MspI restriction endonuclease enzymes to characterize methylation patterns, at the interior cytosine of the sequence CmCGG. Identical molecular weight banding patterns were found for both HpaII and MspI digests in normal dorsal prostate (NDP) used as a control. Both the treated and non-treated Dunning R-3327 cells digested with HpaII and MspI, displayed similar banding profiles from those seen in NDP solid tissues, indicative of a progressive loss of methylation at CCGG sites.
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PMID:Genomic methylation patterns of the Dunning R-3327 prostate adenocarcinoma system. 855 11

Human hepatoma Hep 3B cells underwent apoptosis in response to 100 microM all-trans retinoic acid (RA) in full serum (10% fetal calf serum) condition in vitro. Cell death began approximately 24 h following treatment, with more than 80% of the cells dead after 60 h. The dead cells, mainly detached cells, exhibited condensed chromatin and DNA fragmentation, which are indicative of endonuclease activation and are the hallmarks of apoptosis in epithelial cells. Concurrent exposure to 1 microM cycloheximide (CX) prevented approximately 50% of cell death and DNA fragmentation induced by RA. Thus, other toxic injury to the cells as well as apoptosis might be involved in cell death. Sixty hours exposure of RA decreased the percentage of cells in G1 phase (16.3 +/- 0.4% versus 52.4 +/- 2.1%; P < or = 0.01) and in G2/M phase (13.4 +/- 1.2% versus 21.2 +/- 0.7%; P < or = 0.01), but did not change percent of cells in S phase (20.8 +/- 0.2% versus 20.7 +/- 0.5%) of the cell cycle compared with control. RA may have caused accumulation of Hep 3B cells before G1 phase, and that G0/G1 transition is a main check point in the active process of apoptosis. Electron micrographs of the cells treated with RA revealed typical morphologic changes of apoptosis, besides toxic injury to the cells. These data strongly indicate that RA is able to induce apoptosis and the induction of apoptosis may contribute to the antitumor activity of RA against hepatoma cells.
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PMID:Apoptosis induced by retinoic acid in Hep 3B cells in vitro. 891 80


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