scholarly journals Stimulation of intracellular topoisomerase I activity by vasopressin and thrombin. Differential regulation by pertussis toxin

1989 ◽  
Vol 262 (2) ◽  
pp. 485-489 ◽  
Author(s):  
P Nambi ◽  
M Mattern ◽  
J O Bartus ◽  
N Aiyar ◽  
S T Crooke
Keyword(s):  
Pertussis Toxin ◽  
Topoisomerase I ◽  
Topoisomerase Ii ◽  
Dna Topoisomerase ◽  
Strand Breaks ◽  
Surface Receptors ◽  
Aortic Smooth Muscle ◽  
Strand Breakage ◽  
Dna Strand ◽  
Dna Strand Breakage

Incubation of cultured rat aortic smooth muscle cells (A-10, ATCC CRL 1476) with [8-arginine]vasopressin (AVP) or thrombin increased the amount of DNA strand breakage induced by camptothecin, an inhibitor of topoisomerase I (DNA topoisomerase; EC 5.99.1.2) and transiently stimulated the extractable activity of this enzyme. Both topoisomerase-related responses were prevented by treatment of the cells with AVP or thrombin plus the appropriate receptor antagonist. The increase in strand breakage mediated by AVP and thrombin depended on the concentration of hormone. Neither AVP nor thrombin had any effect on strand breaks obtained with the epipodophyllotoxin VM-26, an inhibitor of topoisomerase II [DNA topoisomerase (ATP-hydrolysing); EC 5.99.1.3]. Pretreatment of the cells with pertussis toxin partially inhibited thrombin-mediated increases in camptothecin-induced strand breakage whereas AVP-mediated increases were unaffected. These results are consistent with the notion that AVP and thrombin induce a transient increase in intracellular topoisomerase I activity via interactions with their respective cell surface receptors and that the effects of the activation of these receptors are mediated by different G-proteins.

Topoisomerase II inhibition prevents anaphase chromatid segregation in mammalian cells independently of the generation of DNA strand breaks

1993 ◽  
Vol 105 (2) ◽  
pp. 563-569 ◽  
Author(s):  
D.J. Clarke ◽  
R.T. Johnson ◽  
C.S. Downes
Keyword(s):  
Chromosome Segregation ◽  
Mammalian Cells ◽  
Topoisomerase Ii ◽  
Dna Strand Breaks ◽  
Temperature Sensitive ◽  
Dna Topoisomerase ◽  
Strand Breaks ◽  
Temperature Sensitive Mutants ◽  
Chromatid Segregation ◽  
Dna Strand

Yeast temperature-sensitive mutants of DNA topoisomerase II are incapable of chromosome condensation and anaphase chromatid segregation. In mammalian cells, topoisomerase II inhibitors such as etoposide (VP-16-123) have similar effects. Unfortunately, conclusions drawn from work with mammalian cells have been limited by the fact that the standard inhibitors of topoisomerase II also generate DNA strand breaks, which when produced by other agents (e.g. ionizing radiation) are known to affect progression into and through mitosis. Here we show that the anti-tumour agent ICRF-193, recently identified as a topoisomerase II inhibitor operating by a non-standard mechanism, generates neither covalent complexes between topoisomerase II and DNA, nor adjacent DNA strand breaks, in mitotic HeLa. However, the drug does prevent anaphase segregation in HeLa and PtK2 cells, with effects similar to those of etoposide. We therefore conclude that topoisomerase II function is required for anaphase chromosome segregation in mammalian cells, as it is in yeast.

scholarly journals DNA Repair Functions That Control Sensitivity to Topoisomerase-Targeting Drugs

2004 ◽  
Vol 3 (1) ◽  
pp. 82-90 ◽  
Author(s):  
Mobeen Malik ◽  
John L. Nitiss
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Topoisomerase I ◽  
Topoisomerase Ii ◽  
Excision Repair ◽  
Dna Strand Breaks ◽  
Dna Topology ◽  
Strand Breaks ◽  
Wide Range ◽  
Dna Strand

ABSTRACT DNA topoisomerases play critical roles in a wide range of cellular processes by altering DNA topology to facilitate replication, transcription, and chromosome segregation. Topoisomerases alter DNA topology by introducing transient DNA strand breaks that involve a covalent protein DNA intermediate. Many agents have been found to prevent the religation of DNA strand breaks induced by the enzymes, thereby converting the enzymes into DNA-damaging agents. Repair of the DNA damage induced by topoisomerases is significant in understanding drug resistance arising following treatment with topoisomerase-targeting drugs. We have used the fission yeast Schizosaccharomyces pombe to identify DNA repair pathways that are important for cell survival following drug treatment. S. pombe strains carrying mutations in genes required for homologous recombination such as rad22A or rad32 (homologues of RAD52 and MRE11) are hypersensitive to drugs targeting either topoisomerase I or topoisomerase II. In contrast to results observed with Saccharomyces cerevisiae, S. pombe strains defective in nucleotide excision repair are also hypersensitive to topoisomerase-targeting agents. The loss of DNA replication or DNA damage checkpoints also sensitizes cells to both topoisomerase I and topoisomerase II inhibitors. Finally, repair genes (such as the S. pombe rad8+ gene) with no obvious homologs in other systems also play important roles in causing sensitivity to topoisomerase drugs. Since the pattern of sensitivity is distinct from that seen with other systems (such as the S. cerevisiae system), our results highlight the usefulness of S. pombe in understanding how cells deal with the unique DNA damage induced by topoisomerases.

scholarly journals Contrasting patterns of DNA strand breakage and ADP-ribosylation- dependent DNA ligation during granulocyte and monocyte differentiation

Blood ◽  
1987 ◽  
Vol 69 (4) ◽  
pp. 1114-1119 ◽  
Author(s):  
Z Khan ◽  
GE Francis
Keyword(s):  
Structural Changes ◽  
Dna Supercoiling ◽  
Monocytic Differentiation ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Colony Stimulating Activity ◽  
Strand Breakage ◽  
Macrophage Colony ◽  
Dna Strand ◽  
Dna Strand Breakage

Previous studies have shown that structural changes in DNA, including the ligation of pre-existing DNA breaks and the opening and closure of new breaks, occur shortly after exposure of granulomonocytic precursors (CFU-GM) to granulocyte-macrophage colony stimulating activity (GM- CSA). Monocytic differentiation of CFU-GM is selectively inhibited by compounds known to inhibit the nuclear enzyme ADP-ribosyl transferase (ADPRT). Since this enzyme, which transfers ADP-ribose units to chromatin proteins, is known to activate DNA ligase, we attempted to determine whether ligation of one or both types of DNA break is required for monocytic differentiation. Breaks in DNA were examined using the nucleoid sedimentation technique in which DNA breaks cause loss of DNA supercoiling in nucleoids and concomitant changes in their sedimentation through neutral sucrose gradients. We here report that two distinct patterns of DNA strand breakage and ligation are associated with differentiation to the granulocyte and monocyte lineages. Monocytic inducers (phorbolester and vitamin D3) predominantly produce closure of pre-existing strand breaks, whereas granulocytic inducers (granulocyte colony stimulating activity, G-CSA; retinoic acid) cause opening and closure of new breaks. Only ligation of the pre-existing breaks is highly sensitive to inhibition by 3- methoxybenzamide (a potent ADPRT inhibitor), and only monocytic differentiation is impaired by addition of this compound. These findings suggest that DNA structural changes may be directly involved in granulocyte-macrophage switching.

scholarly journals Inhibition of replicon initiation in human cells following stabilization of topoisomerase-DNA cleavable complexes.

1991 ◽  
Vol 11 (7) ◽  
pp. 3711-3718 ◽  
Author(s):  
W K Kaufmann ◽  
J C Boyer ◽  
L L Estabrooks ◽  
S J Wilson
Keyword(s):  
Ataxia Telangiectasia ◽  
Topoisomerase I ◽  
Cellular Response ◽  
Human Fibroblasts ◽  
Dna Strand Breaks ◽  
Velocity Sedimentation ◽  
Type I ◽  
Dna Topoisomerase ◽  
Strand Breaks ◽  
Dna Strand

Diploid human fibroblast strains were treated for 10 min with inhibitors of type I and type II DNA topoisomerases, and after removal of the inhibitors, the rate of initiation of DNA synthesis at replicon origins was determined. By alkaline elution chromatography, 4'-(9-acridinylamino)methanesulfon-m-anisidide (amsacrine), an inhibitor of DNA topoisomerase II, was shown to produce DNA strand breaks. These strand breaks are thought to reflect drug-induced stabilization of topoisomerase-DNA cleavable complexes. Removal of the drug led to a rapid resealing of the strand breaks by dissociation of the complexes. Velocity sedimentation analysis was used to quantify the effects of amsacrine treatment on DNA replication. It was demonstrated that transient exposure to low concentrations of amsacrine inhibited replicon initiation but did not substantially affect DNA chainelongation within operating replicons. Maximal inhibition of replicon initiation occurred 20 to 30 min after drug treatment, and the initiation rate recovered 30 to 90 min later. Ataxia telangiectasia cells displayed normal levels of amsacrine-induced DNA strand breaks during stabilization of cleavable complexes but failed to downregulate replicon initiation after exposure to the topoisomerase inhibitor. Thus, inhibition of replicon initiation in response to DNA damage appears to be an active process which requires a gene product which is defective or missing in ataxia telangiectasia cells. In normal human fibroblasts, the inhibition of DNA topoisomerase I by camptothecin produced reversible DNA strand breaks. Transient exposure to this drug also inhibited replicon initiation. These results suggest that the cellular response pathway which downregulates replicon initiation following genotoxic damage may respond to perturbations of chromatin structure which accompany stabilization of topoisomerase-DNA cleavable complexes.

Collagen is a survival factor against LPS-induced apoptosis in cultured sheep pulmonary artery endothelial cells

1995 ◽  
Vol 269 (2) ◽  
pp. L171-L177 ◽  
Author(s):  
D. G. Hoyt ◽  
R. J. Mannix ◽  
J. M. Rusnak ◽  
B. R. Pitt ◽  
J. S. Lazo
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Artery ◽  
Dna Fragmentation ◽  
High Molecular Weight Dna ◽  
Strand Breaks ◽  
Strand Breakage ◽  
Dna Strand ◽  
Induced Apoptosis ◽  
Dna Strand Breakage

Lipopolysaccharide (LPS) causes direct pulmonary endothelial injury that can precipitate cell death. We investigated the ability of LPS to produce apoptosis in sheep pulmonary artery endothelial cells (SPAEC) grown in monolayer on plastic or collagen. When SPAEC were grown on plastic, LPS (100 ng/ml) caused internucleosomal DNA fragmentation (IDF) to 180- to 200-base pair ladders after 4 h. Higher-order chromatin damage, producing 50-kilobase DNA fragments, occurred within 2 h. Significant DNA strand breaks were seen in attached cells within 1 h incubation with > or = 1 ng LPS/ml, using in situ labeling by break extension (ISBE). DNA strand breakage in attached cells peaked after 2 h and remained elevated after 4 h. Detachment of SPAEC from the monolayer did not begin until 4 h. SPAEC cultured on collagen were protected from LPS-induced apoptosis; DNA damage measured by IDF, high-molecular-weight DNA fragmentation, and ISBE were suppressed. The protective effect of collagen was not due to inactivation of LPS. Thus LPS-induced apoptosis occurs in SPAEC after genotoxic damage and this process is suppressed by the extracellular matrix.

scholarly journals Transient activation of topoisomerase I in leukotriene D4 signal transduction in human cells

1990 ◽  
Vol 265 (1) ◽  
pp. 101-107 ◽  
Author(s):  
M R Mattern ◽  
S Mong ◽  
S M Mong ◽  
J O'L Bartus ◽  
H M Sarau ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Topoisomerase I ◽  
Culture Medium ◽  
U937 Cells ◽  
Leukotriene D4 ◽  
Strand Breakage ◽  
Acid Metabolites ◽  
Acid Release ◽  
Dna Strand ◽  
Dna Strand Breakage

U937 human monoblast cells incubated with leukotriene D4 (LTD4) rapidly released arachidonic acid metabolites into the culture medium. Release was suppressed by the high-affinity LTD4 receptor antagonist SK&F 104353. Arachidonic acid release induced by LTD4 has been linked to a rapid induction of gene expression, and the propagation of the receptor binding signal is probably associated with enzymes that regulate gene expression. We have studied the participation of DNA topoisomerase I in LTD4 signal transduction. LTD4-specific release of arachidonic acid metabolites was inhibited (60-80%) by the topoisomerase I inhibitor camptothecin. LTD4 increased protein-linked DNA strand breakage induced by camptothecin in U937 cells; this enhancement was prevented by coincubation of the cells with LTD4 plus the receptor antagonist SK&F 104353. In addition, LTD4 produced a rapid transient increase in extractable topoisomerase I activity, which was maximum within the first 10 min after addition of LTD4 to the culture medium. Incubation of cultures for greater than 10 min with LTD4 before the addition of camptothecin resulted in no enhancement of camptothecin-induced DNA strand breakage, consistent with a reversal of topoisomerase I activation. Staurosporine, an inhibitor of protein kinase C, blocked LTD4-induced arachidonic acid release and attenuated the effect of LTD4 on camptothecin-induced DNA strand breakage. These results are consistent with the view that the regulation of topoisomerase I activity is involved in the propagation of LTD4-mediated signals in U937 cells.

scholarly journals Contrasting patterns of DNA strand breakage and ADP-ribosylation- dependent DNA ligation during granulocyte and monocyte differentiation

Blood ◽  
1987 ◽  
Vol 69 (4) ◽  
pp. 1114-1119 ◽  
Author(s):  
Z Khan ◽  
GE Francis
Keyword(s):  
Structural Changes ◽  
Dna Supercoiling ◽  
Monocytic Differentiation ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Colony Stimulating Activity ◽  
Strand Breakage ◽  
Macrophage Colony ◽  
Dna Strand ◽  
Dna Strand Breakage

Abstract Previous studies have shown that structural changes in DNA, including the ligation of pre-existing DNA breaks and the opening and closure of new breaks, occur shortly after exposure of granulomonocytic precursors (CFU-GM) to granulocyte-macrophage colony stimulating activity (GM- CSA). Monocytic differentiation of CFU-GM is selectively inhibited by compounds known to inhibit the nuclear enzyme ADP-ribosyl transferase (ADPRT). Since this enzyme, which transfers ADP-ribose units to chromatin proteins, is known to activate DNA ligase, we attempted to determine whether ligation of one or both types of DNA break is required for monocytic differentiation. Breaks in DNA were examined using the nucleoid sedimentation technique in which DNA breaks cause loss of DNA supercoiling in nucleoids and concomitant changes in their sedimentation through neutral sucrose gradients. We here report that two distinct patterns of DNA strand breakage and ligation are associated with differentiation to the granulocyte and monocyte lineages. Monocytic inducers (phorbolester and vitamin D3) predominantly produce closure of pre-existing strand breaks, whereas granulocytic inducers (granulocyte colony stimulating activity, G-CSA; retinoic acid) cause opening and closure of new breaks. Only ligation of the pre-existing breaks is highly sensitive to inhibition by 3- methoxybenzamide (a potent ADPRT inhibitor), and only monocytic differentiation is impaired by addition of this compound. These findings suggest that DNA structural changes may be directly involved in granulocyte-macrophage switching.

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