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PubMed2006

A combination of E. coli DNA fragments and modified lipopolysaccharides as a cancer immunotherapy.

The use of Escherichia coli DNA or lipopolysaccharide (LPS) as an immunotherapy is often associated with unacceptable toxicity and insufficient therapeutic effects. In this study, we investigated the efficacy of using a combination of bacterial DNA fragments and LPS as an anticancer agent. LPS was isolated from an E. coli strain expressing short-carbohydrate-chain-containing LPS and subjected to alkaline hydrolysis to remove lipid A. The ability to induce tumor necrosis factor-alpha (TNF-alpha) release in human whole blood cells was significantly lower for the LPS devoid of lipid A than for its parent form. The immunostimulating activity of E. coli DNA fragments of various sizes were tested. Those of 0.2-0.5 kb in size exhibited the highest activity in whole blood assays, whereas those of size 0.5-2.0 kb exhibited the highest adjuvant activity in mice. A combination of 0.5-2.0-kb DNA fragments and modified LPS at a ratio of 100:1, designated CIA07, exhibited higher immunostimulating activity than each substance alone, and its antitumor activity was significantly higher than that of Bacillus Calmette-Guerin in a mouse bladder cancer model. An intraperitoneal injection of CIA07 at a dose of 25mg/kg body weight caused no apparent adverse effects in mice and guinea pigs. Taken together, these data demonstrate that CIA07 exhibits potent immunostimulating activity with no apparent toxicity, and therefore warrant the further development of CIA07 as an immunotherapy for cancer treatment.

Animals↗
PubMed2001

Both subtelomeric regions are required and sufficient for specific DNA fragmentation during macronuclear development in Stylonychia lemnae.

BACKGROUND: Programmed DNA-reorganization and DNA-elimination events take place frequently during cellular differentiation. An extreme form of such processes, involving DNA reorganization, DNA elimination and DNA fragmentation, is found during macronuclear differentiation in hypotrichous ciliates. Ciliated protozoa can therefore serve as a model system to analyze the molecular basis of these processes during cellular differentiation in eukaryotic cells. RESULTS: Using a biological approach to identify cis-acting sequences involved in DNA fragmentation, we show that in the hypotrichous ciliate Stylonychia lemnae sequences required for specific DNA processing are localized in the 3'- and the 5'-subtelomeric regions of the macronuclear precursor sequence. They can be present at various positions in the two subtelomeric regions, and an interaction between the two regions seems to occur. Sequence comparison revealed a consensus inverted repeat in both subtelomeric regions that is almost identical to the putative Euplotes chromosome breakage sequence (E-Cbs), also identified by sequence comparison. When this sequence was mutagenized, a processed product could no longer be detected, demonstrating that the sequence plays a crucial role in DNA processing. By injecting a construct into the developing macronucleus, which exclusively contains the subtelomeric regions of the Stylonychia alphal-tubulin gene, we show that subtelomeric regions are not only required but are also sufficient for DNA processing in Stylonychia. CONCLUSIONS: Our results indicate that an inverted repeat with the core sequence 5'-TGAA present in both subtelomeric regions acts as a Cbs in Stylonychia. The results allow us to propose a mechanistic model for DNA processing in this ciliate.

Animals↗
PubMed1998

Differences in ethidium bromide and 4'-6-diamidino-2-phenylindole staining profiles with regard to DNA fragmentation during apoptosis.

To simply and directly evaluate DNA fragmentation during apoptosis induced in mouse cultured hepatocytes by an anti-Fas antibody, we examined the fluorescence intensity in cell nuclei stained with ethidium bromide and 4'-6-diamidino-2-phenylindole by optiphoto fluorescence microscopy. The intensity of the former staining for the nuclear DNA of apoptotic cells was clearly decreased compared to that of non-apoptotic cells, whereas no difference in the fluorescence intensity for the latter stain between the apoptotic and non-apoptotic groups was observed. Thus, the use of optiphoto fluorescence microscopy, in conjunction with both stains, constitutes a useful tool for the evaluation of apoptotic DNA fragmentation.

Animals↗
PubMed1998

Relationship between magnitude of hypothermia during ischemia and preventive effect against post-ischemic DNA fragmentation in the gerbil hippocampus.

Protective effect of hypothermia against DNA fragmentation in hippocampal CA1 field after transient forebrain ischemia in gerbils was evaluated by changing the magnitude of hypothermia. Inhibition of DNA fragmentation was proportional to the magnitude of hypothermia. The result indicates that, in terms of susceptibility to ischemia, hippocampal CA1 neurons are sensitive to a relatively small decrement of temperature, with temperatures </=35 degreesC being critical for the prevention of apoptotic process following transient forebrain ischemia.

Animals↗
PubMed1998

Gamete-specific DNA fragmentation in unfertilized human oocytes after intracytoplasmic sperm injection.

The objective of the present study was to assess the integrity of maternal and/or paternal chromatin in injected oocytes that remained unfertilized after intracytoplasmic sperm injection (ICSI). The study was performed on 102 oocytes that failed to show pronuclear formation 18-20 h after ICSI. We used chromatin labelling with 4,6-diamidino-2-phenylindole (DAPI) to identify maternal and paternal chromatin, coupled with biotin-mediated end-labelling to assess DNA fragmentation in each gamete. It was shown that 50% of oocytes without pronuclear formation following ICSI contained chromatin with damaged DNA, and that the source of the DNA fragmentation was equally divided between the spermatozoon (25.8%) and the oocyte (24.4%). A significantly greater proportion of condensed spermatozoa in human oocytes had damaged DNA, compared to decondensed spermatozoa (24.7 compared to 5.9%, P=0.002). There was a significant increase in the incidence of DNA fragmentation in oocytes from patients older than 35 years (65+/-1.2%) compared to those from younger patients (36+/-1.0%) (P < 0.05). Further, 17% of unfertilized oocytes contained no paternal chromatin. Thus, DNA fragmentation in both spermatozoa and oocytes is associated with failure of fertilization in ICSI. In some cases of severe male factor infertility, a significant proportion of spermatozoa injected into oocytes may contain fragmented DNA. Injection of oocytes with spermatozoa containing abnormal chromatin will probably result in failure of sperm decondensation and fertilization. In older women, a significant proportion of oocytes injected may contain fragmented DNA. These observations may explain the consistent inability of most clinics to achieve fertilization rates higher than 65% with ICSI.

Adult↗
PubMed1989

Inhibition of DNA fragmentation in thymocytes and isolated thymocyte nuclei by agents that stimulate protein kinase C.

Glucocorticoid hormones and Ca2+ ionophores stimulate a suicide process in immature thymocytes, known as apoptosis or programmed cell death, that involves extensive DNA fragmentation. We have recently shown that a sustained increase in cytosolic Ca2+ concentration stimulates DNA fragmentation and cell killing in glucocorticoid- or ionophore-treated thymocytes. However, a sustained increase in the cytosolic Ca2+ level also mediates lymphocyte proliferation, suggesting that apoptosis is blocked in proliferating thymocytes. In this study we report that phorbol esters, which selectively stimulate protein kinase C (PKC), blocked DNA fragmentation and cell death in thymocytes exposed to Ca2+ ionophore or glucocorticoid hormone. The T cell mitogen, concanavalin A, which stimulates thymocytes by a mechanism that involves PKC activation, caused concentration-dependent increases in the cytosolic Ca2+ level that did not result in DNA fragmentation, but incubation with concanavalin A and the PKC inhibitor H-7 (1-(5-isoquinolinylsulfonyl)-2-methylpiperazine) resulted in both DNA fragmentation and cell death. Phorbol ester directly inhibited Ca2+-dependent DNA fragmentation in isolated thymocyte nuclei. Our results strongly suggest that PKC activation blocks thymocyte apoptosis by preventing Ca2+-stimulated endonuclease activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Oxygen tension influences DNA fragmentation and cell death in glucocorticoid-treated thymocytes.

Internucleosomal DNA fragmentation and cell death induced by dexamethasone in rat thymocytes were inhibited when cells were cultured in 95% N2/5% CO2 atmosphere, in which oxygen was rapidly reduced to under 0.5%. DNA fragmentation was delayed by a less severe hypoxia in 5% oxygen whilst in cell cultured in high oxygen atmosphere (95% O2) cell death was increased. On the other hand, prolonged oxygen deprivation caused an increase of spontaneous apoptotic cell death. Hypoxia also inhibited DNA fragmentation induced by calcium ionophore A23187, but not by topoisomerase inhibitor camptothecin. These data support the hypothesis of the involvement of oxygen reactive species in calcium-mediated apoptosis and suggest a complex role of oxygen in the modulation of programmed cell death.

Animals↗
PubMed1983

lambda DNA-fragmenting actions of ascorbic acid and triose reductone in the presence of Cu2+.

Lambda DNA-fragmenting actions of ascorbic acid (AsA) and triose reductone (TR) in the presence of Cu2+ were studied. The mixture of AsA or TR and Cu2+ caused a marked fragmentation of lambda DNA (3.2 X 10(7) daltons) within the first 1 min of reaction. Further incubation resulted in accumulation of the most abundant species of fragmented lambda DNA having a molecular weight of 1.3 X 10(5) daltons. The mixture of AsA or TR and Cu2+ fragmented calf thymus DNA to produce the fragmented DNA of which 5'-OH terminal groups have a mixture of free OH groups and phosphodiester linkage. The mixture of AsA or TR and Cu2+ was also found to fragment lambda DNA to produce dCMP predominantly as 5'-OH terminal nucleotides.

Adenosine Triphosphate↗
PubMed2003

Analysis of parental strain DNA fragments existing in GEMs-Fhhh.

There were 6 target DNA fragments of the three parental strains existing in the cell of GEMs (genetically engineered microorganism strain) Fhhh measured in this research by PCR(polymerase chain reaction). The determination showed that GEMs Fhhh contained all the 6 target DNA fragments, mnp1, mnp2, lip1, lip2, FLO1 and 16S rDNA, and had the molecular genetic stability. Meanwhile the PCR production of each parental strain could only had its target DNA fragments and was different from each other. It may illustrate that the technique of the inter-kingdom protoplast fusion for the construction of GEMs Fhhh through the process of intercellular gene recombination could be used as a reliable bioengineering technique to create the specific functional stain for the pollution control.

Bacteria↗
PubMed1983

DNA fragmentation in S49 lymphoma cells killed with glucocorticoids and other agents.

The effects of glucocorticoids on DNA integrity in the mouse S49 lymphoma cell line were assessed. DNA cleavage at the internucleosomal regions was observed, and this response was correlated to the dose of hormone used and the time of treatment. Also, an apparent steroid specificity was observed: internucleosomal cleavage was associated only with treatment of the cells with glucocorticoids. Cells treated with dibutyryl cyclic AMP (which also causes lymphocytolysis) also exhibited DNA cleavage. However, when cells were killed with various DNA synthesis inhibitors and other lethal agents, the same DNA cleavage pattern was observed. Furthermore, new protein synthesis did not seem to be required, since cells killed with puromycin and cycloheximide also exhibited internucleosomal DNA fragmentation. Although DNA fragmentation may not be a specific early effect of glucocorticoid-mediated lymphocytolysis, it may be the final, irrevocable step in this complex process.

Animals↗
PubMed1999

Induction and rejoining of large DNA fragments after ion irradiation.

Radiation-induced DNA double-strand breaks (DSBs) were analyzed by separating large DNA fragments by pulsed-field gel electrophoresis. Human U-343MG glioma and K562 erythroleukemia cells were irradiated with 60Co gamma rays or nitrogen ions with high linear energy transfer (125 keV/microm). By comparing the fraction of DNA released into the gel below different size thresholds, corresponding to megabase-pair-sized DNA fragments, the relative effectiveness of the nitrogen ions was found to be dependent on both dose and the threshold size used in the evaluation. This dose dependence was most evident for the smallest threshold (6 Mbp) and was due to a linear dose response for release of the fragments for the ions compared to the curvilinear response for the gamma rays. The two curves intersected, and the relative yield of fragments (nitrogen ions/gamma rays) decreased from more than 3 below 1.5 Gy to 0.8 at 30 Gy. For the larger sizes (6-10.5 Mbp), the relative yield was constant at around 0.7. Thus the ion-induced fragments were shifted to smaller sizes compared to the 60Co gamma rays, and the data for nitrogen ions could not be fitted to random fragment distributions at doses < or =20 Gy. From these results, we conclude that a substantial fraction of the DSBs induced by heavy ions were nonrandomly distributed, correlated with DSBs within a region of < or =2 Mbp. After a dose of 20 Gy, the rejoining curves for ion-induced DSBs were different for each fragment size, resulting in different levels of unrejoined breaks after 6 h.

DNA↗
PubMed2005

Modulation of DNA fragmentation factor 40 nuclease activity by poly(ADP-ribose) polymerase-1.

Poly(ADP-ribose) polymerase-1 (PARP-1) influences numerous cellular processes, including DNA repair, transcriptional regulation, and caspase-independent cell death, by utilizing NAD(+) to synthesize long chains of poly(ADP-ribose) (PAR) on target proteins, including itself. During the apoptotic response, caspases-3 and -7 cleave PARP-1, thereby inhibiting its activity. Here, we have examined the role of PARP-1 activation and cleavage in the latter stages of apoptosis in response to DNA fragmentation. PARP-1 poly(ADP-ribosyl)ation correlated directly with induction of apoptosis by the lipid peroxidation product, 4-hydroxy-2-nonenal. A significant decrease in PAR accumulation was observed upon caspase or DNA fragmentation factor 40 (DFF40) inhibition. Because DNA fragmentation mediated by DFF40 augmented PARP-1 modification status in apoptotic cells, we hypothesized that PARP-1 alters DFF40 function following PAR accumulation. Indeed, PARP-1, in the presence of NAD(+), significantly decreased DFF40 activity on plasmid substrates. Conversely, PARP-1 enhanced the DNase activity of DFF40 in the absence of NAD(+). The inhibition of DFF40 activity in the presence of NAD(+) was reduced by co-incubation with poly(ADP-ribose) glycohydrolase and a PARP inhibitor. Additionally, caspase-cleaved PARP-1, in the presence of NAD(+), did not inhibit DFF40 activity significantly. Our results suggest that PARP-1 poly(ADP-ribosyl)ation is a terminal event in the apoptotic response that occurs in response to DNA fragmentation and directly influences DFF40 activity.

Animals↗
PubMed1994

Adenosine stimulates DNA fragmentation in human thymocytes by Ca(2+)-mediated mechanisms.

Incubation of human thymocytes with an optimum concentration of adenosine and its receptor site agonist, 2-chloroadenosine, induced increases in intracellular cyclic AMP (cAMP) (from a resting 0.6 +/- 0.1 to 4.1 +/- 0.2 pmol/10(7) cells within 5 min) and Ca2+ (from the resting 85 +/- 7 nM to a peak of 210 +/- 25 nM) levels and resulted in internucleosomal DNA fragmentation and cell death (apoptosis). Other adenosine analogues were also effective at inducing DNA fragmentation, the order of potency being 2-p-(carboxyethylphenylethylamino)-5'-carboxyamidoadenosine < 5'-(N-ethylcarboxamide)adenosine < or = cyclopentyladenosine < 2-chloroadenosine (2-CA). 2-CA treatment (with an optimum concentration of 40 microM) selectively depleted a thymocyte subpopulation (15-20% of the total cells) which expressed higher levels of the CD3 molecule and which was found mainly in the CD4+CD8+ double positive immature thymocyte population. DNA fragmentation was prevented by the addition of actinomycin D or cycloheximide to the thymocyte suspension, indicating that this process required both mRNA and protein synthesis. Endonuclease activation and cell killing were dependent on an early, sustained increase in cytosolic Ca2+ concentration, most of which was of extracellular origin and was a result of an adenosine-induced inositol trisphosphate release. Other agents known to elevate intracellular cAMP levels by different mechanisms failed to induce similar DNA fragmentation, but enhanced the effect of adenosine. This suggested a supporting role for cAMP in adenosine-induced DNA fragmentation. Phorbol dibutyrate, a protein kinase. C activator, previously shown to inhibit Ca(2+)-dependent DNA fragmentation and cell killing in human thymocytes [McConkey, Hartzell, Jondal and Orrenius (1989) J. Biol. Chem. 264, 13399-13402], at 60 ng/ml concentration also prevented adenosine-induced DNA fragmentation when added prior to adenosine. This suggested a complex cross-talk between the adenosine-triggered signal transduction cascade and the activation state of protein kinase C in regulating apoptosis of human thymocytes.

2-Chloroadenosine↗
PubMed1995

Temporal profile of in situ DNA fragmentation after transient middle cerebral artery occlusion in the rat.

We measured the temporal profile and anatomic distribution of cells exhibiting DNA fragmentation at various durations of reperfusion after middle cerebral artery (MCA) occlusion in the rat. Focal cerebral ischemia was induced in male Wistar rats (n = 62) using an intraluminal monofilament blockade of the MCA. After 2 h of MCA occlusion, the animals were killed at different durations of reperfusion (0.5, 3, 6, 9, and 12 h and 1, 2, 4, 7, 14, 21, and 28 days, n = 4 per time point). Sham-operated rats (n = 4) and normal rats not subjected to any surgical procedure (n = 4) were used as controls. Coronal brain sections (5 microns) were analyzed, using an in situ ApopTag kit, hematoxylin and eosin, and immunohistochemical double-staining methods. Six rats subjected to 2 h of MCA occlusion were killed at 24 h for measurement of DNA fragmentation by gel electrophoresis. Our data indicate that within a coronal section, DNA fragmentation was present in zero to three cells in each hemisphere of normal and sham-operated rats as well as in the contralateral hemisphere of ischemic rats. The number of cells exhibiting DNA fragmentation increased as early as 0.5 h (8 +/- 6), peaked at 24-48 h (213 +/- 59), and persisted for 4 weeks (10 +/- 2) after onset of reperfusion (p < 0.01). Groups of cells exhibiting DNA fragmentation (> 95% neurons) were located primarily in the inner boundary zone of the infarct. With use of gel electrophoresis, purified DNA obtained from the ischemic tissue exhibited the characteristic nucleosome ladder pattern associated with apoptosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Comparative analysis of the transcripts mapped in the BamHI DNA fragment B of avirulent HSV-1 HFEM, virulent HSV-1 F, and their intratypic recombinant viruses.

HSV-1 HFEM, whose genome harbors a deletion of 4.1 kbp (0.762 to 0.789 map units (mu] is avirulent for mice and tree shrews by the intraperitoneal (i.p.) application route. Insertion of the BamHI DNA fragment B (0.738 to 0.809 mu) and/or the MluI DNA fragment (0.7615 to 0.796 mu) molecularly cloned from virulent HSV-1 F, restored the i.p. pathogenicity to strain HFEM and led to the isolation of virulent intratypic recombinants. In order to determine the RNA transcripts mapped in the BamHI DNA fragment B of the HSV-1 HFEM, HSV-1 F, and their intratypic recombinants R15, R19, R26, and R-Ml-C1, a comparative analysis was performed using Northern blot hybridizations. Two novel RNA transcripts of 3.5 and 1.5 kb were detected which hybridize to the left terminus (0.738 to 0.746 mu) of the BamHI DNA fragment B. The 1.5 kb RNA transcript was missing in the avirulent HSV-1 HFEM. Hybridization with the BssHII DNA fragment F (0.760 to 0.762 mu) led to detection of a 3.5 kb RNA transcript by HSV-1 HFEM which was missing in all other viruses tested. In contrast a 1.5 kb RNA transcript was detectable in all other virus strains with the exception of HSV-1 HFEM. The 3.5 kb transcript hybridized to the right-hand flank of the deleted region in the genome of HSV-1 HFEM (Asp718/SalI DNA fragment; 0.786 to 0.79 mu). The detection of the novel 1.5 kb RNA, which is missing in HSV-1 HFEM, and the appearance of the newly transcribed 3.5 kb RNA in HSV-1 HFEM only, indicates a new open reading frame in this particular region as a consequence of the fusion of the DNA sequences at both ends of the deletion in the genome of HSV-1 HFEM.

Chromosome Deletion↗
PubMed2003

[Comparison of specific genomic DNA fragment between Microtus fortis calamorum and Microtus fortis fortis].

Microtus fortis(Taxonomy ID: 100897), also named as reed vole, is classified as Microtus, Micotinae, Cricetidae, Rodentia, Mammalia on taxonomy. Microtus fortis mainly distributes in China. Some areas of Russia, North Korea and Mongolia close to Northeast borderland of China also have a small number of Microtus fortis in distribution. Microtus fortis in China has principally 4 subspecies, and most of them live is the drainage area of Yangtse River. Schistosoma japonicum (one of commonly parasites in China) can infect about 40 kinds of mammalian animals, including the human being, but could not infect Microtus foris. It is known as the only animal in Dongting Lake region of China which has the ability of natural resistance to Schistosoma japonicum. The Microtus fortis domesticated in laboratory has the same biological characteristics as the wild one and these characteristics could be inherited to its progeny steadily. We got a specific DNA fragment from genomic library of Microtus fortis. This DNA fragment in genomic DNA of human beings, Kunming mice, Balb/c mice and C57BL/6J mice could not be detected by dot blot hybridization and PCR, apart from genomic DNA of Microtus fortis. In this report, the differences of genomic DNA in 34 Microtus fortis were compared between Microtus fortis calamorum(Dongting Lake region of southern China) and Microtus fortis fortis (Ningxia province of northern China). The residing localion of these two subspecies is far away about 1,200 kilometers from each other. The genomic DNA of Microtus fortis calamorum and Microtus fortis fortis were extracted and amplified by PCR according to the specific genomic DNAs sequence of Microtus fortis reported previously (Accession number in GenBank: AF277394). The amplified DNA fragments were inserted into pGEM-T easy vector and sequenced. The DNA fragment sequencing results from the two subspecies were compared to detect whether there was any difference. 19 alleles were found from Microtus fortis (20 of Microtus fortis calamorum and 14 of Microtus fortis fortis). The results of multiple sequence alignment showed that 25 single nucleotide polymorphism (SNP) sites were existed in the different Microtus fortis individuals, including transition (G-->A,A-->G,T-->C,C-->T), transversion(G-->T,A-->T,T-->A,C-->A), insertion (CA) and deletion (TGTTTT). The difference of genomic DNA from two subspecies were obvious, especially on the sites of 146, 192, 223, 224 and 235. The insertion of CA on the sites of 223 and 224 as well as A-->G transition on the site of 235 was only occurred in Microtus fortis fortis. They are not found in Microtus fortis calamorum so far. They could be divided into two groups according to phylogenetic tree analysis results, one was the genomic DNA of Microtus fortis calamorum and the other one was that of Microtus fortis fortis. However, the homologues reached up to 98% between two subspecies. These results are very important for us to further understand the genetic background, biological characteristics, evolutionary rule and the anti-schistosoma japonicum mechanism of Microtus fortis at the molecular levels. The specific base changes of the DNA fragment between the two subspecies are probably correlative with the animal immigration, survival conditions, and species evolution.

Animals↗
PubMed2004

Mechanism of acetaminophen-induced apoptosis in cultured cells: roles of caspase-3, DNA fragmentation factor, and the Ca2+ and Mg2+ endonuclease DNAS1L3.

We have recently shown that acetaminophen induces many of the apoptotic traits in hepatoma cells and lymphocytes (Boulares et al. (2002d). In an effort to further investigate the mechanism by which non-metabolized acetaminophen induces apoptosis, we have now examined the roles of caspase-3, the DNA fragmentation factor, and the poly(ADP-ribose) polymerase-1-regulated Ca2+ and Mg2+-dependent endonuclease DNAS1L3 in the induction of such death process. This was achieved with the use of MCF-7 cells, a caspase-3-deficient breast adenocarcinoma cell line, thymocytes isolated from DFF45 (the inhibitory and chaperone subunit of the DNA fragmentation factor subunit, DFF40) deficient mice, and HeLa cells, a DNAS1L3-deficient cervical carcinoma cell line. MCF-7 exhibited a marked resistance to acetaminophen treatment. Ectopic expression of human caspase-3 significantly potentiated the cytotoxic effect of acetaminophen and promoted the release of cytochrome c into the cytosol of treated cells suggesting a direct role for caspase-3 in acetaminophen-induced apoptosis. Expression and cleavage of DFF45 were required but not sufficient for acetaminophen-induced internucleosomal DNA fragmentation. DFF45 gene knockout rendered thymocytes resistant against acetaminophen-induced generation of both large and internucleosomal DNA fragments. The treatment of HeLa cells with acetaminophen resulted in internuclesomal DNA fragmentation only after transfection of these cells with a plasmid encoding the DNAS1L3 gene suggesting that this endonuclease is required for acetaminophen-induced internucleosomal DNA fragmentation. DNAS1L3 expression potentiated the cytotoxic effect of acetaminophen in HeLa cells suggesting an active role in the death process induced by this drug. Altogether, these results demonstrate the specific roles of caspase-3, DNA fragmentation factor, and DNAS1L3 in the process of acetaminophen-induced apoptosis in cultured cells.

Acetaminophen↗
PubMed1995

Inhibition of tumor necrosis factor alpha- and ceramide-induced internucleosomal DNA fragmentation by herbimycin A in U937 cells.

In many tumor cell lines, tumor necrosis factor alpha (TNF alpha) causes apoptosis with characteristic internucleosomal DNA fragmentation. However, the mechanism is largely unknown. Here we examined the involvement of protein tyrosine kinases by using their inhibitors. Among various tyrosine kinase inhibitors tested, only herbimycin A was found to inhibit internucleosomal DNA fragmentation but not apoptotic morphological changes and cell death induced by TNF alpha in U937 cells. Herbimycin A was able to block DNA fragmentation when it was added to the cell culture as late as 1.5 h after TNF alpha treatment. These results demonstrate that herbimycin A selectively inhibits a later event involved in the process of apoptois that results in internucleosomal DNA fragmentation. Sphingomyelinase and ceramide (Cer) induced internucleosomal DNA fragmentation was also inhibited by herbimycin A, supporting the hypothesis that Cer may be a novel second messenger mediating the cytotoxic effect of TNF alpha.

Apoptosis↗