scholarly journals Microcystin-LR, a Cyanobacterial Toxin, Induces DNA Strand Breaks Correlated with Changes in Specific Nuclease and Protease Activities in White Mustard (Sinapis alba) Seedlings

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2045
Author(s):  
Márta M-Hamvas ◽  
Gábor Vasas ◽  
Dániel Beyer ◽  
Eszter Nagylaki ◽  
Csaba Máthé
Keyword(s):  
Vascular Plants ◽  
Sinapis Alba ◽  
Dna Strand Breaks ◽  
White Mustard ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Cyanobacterial Toxin ◽  
Dna Cleaving ◽  
Dna Strand ◽  
Environmental Importance

There is increasing evidence for the induction of programmed cell death (PCD) in vascular plants by the cyanobacterial toxin microcystin-LR (MC-LR). Our aim was to detect the occurrence of PCD-related DNA strand breaks and their possible connections to specific nuclease and protease activities. DNA breaks were studied by the deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) method in the photoperiodically grown dicot model of white mustard (Sinapis alba). In-gel nuclease and protease activity assays showed changes in the activities of specific isoenzymes during treatments with MC-LR. Strand breaks occurred both in the developing root epidermis and cortex. Several isoenzyme activities were related to these breaks, for example: an increase in the activity of neutral 80–75 kDa, acidic high MW (100–120 kDa) and, most importantly, an increase in the activity of neutral 26–20 kDa nucleases, all of them having single-stranded DNA cleaving (SSP nuclease) activities. Increases in the activities of alkaline proteases in the 61–41 kDa range were also detected and proved to be in relation with MC-LR-induced PCD. This is one of the first pieces of evidence on the correlation of PCD-related DNA strand breaks with specific hydrolase activities in a model dicot treated with a cyanobacterial toxin known to have environmental importance.

scholarly journals Clinical response to deoxycoformycin in chronic lymphoid neoplasms and biochemical changes in circulating malignant cells in vivo

Blood ◽  
1988 ◽  
Vol 72 (6) ◽  
pp. 1884-1890 ◽  
Author(s):  
AD Ho ◽  
K Ganeshaguru ◽  
WU Knauf ◽  
G Dietz ◽  
I Trede ◽  
...  
Keyword(s):  
Clinical Response ◽  
Dna Strand Breaks ◽  
Biochemical Changes ◽  
Leukemic Cells ◽  
Malignant Cells ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Lymphoid Neoplasms ◽  
Dna Strand

Abstract Deoxycoformycin (DCF), an adenosine deaminase (ADA) inhibitor, has been shown to be active in lymphoid neoplasms. The mechanism of cytotoxicity might involve accumulation of deoxyadenosine triphosphate (dATP), depletion of the nicotinamide adenine dinucleotide (NAD) and ATP pool, induction of double-stranded DNA strand breaks, or inhibition of S- adenosyl homocysteine hydrolase (SAH-hydrolase). We have investigated the biochemical changes in the circulating malignant cells of patients with chronic leukemia/lymphoma who were treated with DCF (4 mg/m2 weekly). Blood samples were taken from 17 patients with 60% or more circulating leukemic cells before, 4, 24, and 48 hours and five days after the first administration of DCF. Leukemic cells were separated and studied for changes in ADA, dATP, ATP, NAD, and SAH-hydrolase levels and DNA strand breaks and the data analyzed according to clinical response. Inhibition of ADA activity was found in all except one patient at 4 to 24 hours after the first administration of DCF. dATP started to accumulate at four hours, reached a maximum level between 24 and 48 hours, and returned to base values on the fifth day. Intracellular ATP and NAD levels were transiently reduced in some of the patients. However, no correlation between these changes and a clinical response could be found. DNA strand breaks could be studied in 13 patients. A significant increase in DNA breaks at 24 to 48 hours was found in six of the seven responders but only in one of the six nonresponders. At 24 hours, SAH-hydrolase levels were reduced in all seven responders studied, but only in two of the seven nonresponders. The difference in inhibition of SAH-hydrolase was statistically significant (P = .0023). These results suggest that DNA strand breaks and inhibition of SAH-hydrolase correlate with clinical response.

scholarly journals Mechanistic insight into the role of Poly(ADP-ribosyl)ation in DNA topology modulation and response to DNA damage

Mutagenesis ◽  
2019 ◽  
Vol 35 (1) ◽  
pp. 107-118
Author(s):  
Bakhyt T Matkarimov ◽  
Dmitry O Zharkov ◽  
Murat K Saparbaev
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Genotoxic Stress ◽  
Strand Break ◽  
Dna Supercoiling ◽  
Dna Strand Breaks ◽  
Chromosomal Dna ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Dna Strand

Abstract Genotoxic stress generates single- and double-strand DNA breaks either through direct damage by reactive oxygen species or as intermediates of DNA repair. Failure to detect and repair DNA strand breaks leads to deleterious consequences such as chromosomal aberrations, genomic instability and cell death. DNA strand breaks disrupt the superhelical state of cellular DNA, which further disturbs the chromatin architecture and gene activity regulation. Proteins from the poly(ADP-ribose) polymerase (PARP) family, such as PARP1 and PARP2, use NAD+ as a substrate to catalyse the synthesis of polymeric chains consisting of ADP-ribose units covalently attached to an acceptor molecule. PARP1 and PARP2 are regarded as DNA damage sensors that, upon activation by strand breaks, poly(ADP-ribosyl)ate themselves and nuclear acceptor proteins. Noteworthy, the regularly branched structure of poly(ADP-ribose) polymer suggests that the mechanism of its synthesis may involve circular movement of PARP1 around the DNA helix, with a branching point in PAR corresponding to one complete 360° turn. We propose that PARP1 stays bound to a DNA strand break end, but rotates around the helix displaced by the growing poly(ADP-ribose) chain, and that this rotation could introduce positive supercoils into damaged chromosomal DNA. This topology modulation would enable nucleosome displacement and chromatin decondensation around the lesion site, facilitating the access of DNA repair proteins or transcription factors. PARP1-mediated DNA supercoiling can be transmitted over long distances, resulting in changes in the high-order chromatin structures. The available structures of PARP1 are consistent with the strand break-induced PAR synthesis as a driving force for PARP1 rotation around the DNA axis.

scholarly journals Induction of CAF-1 Expression in Response to DNA Strand Breaks in Quiescent Human Cells

2006 ◽  
Vol 26 (5) ◽  
pp. 1839-1849 ◽  
Author(s):  
Arman Nabatiyan ◽  
Dávid Szüts ◽  
Torsten Krude
Keyword(s):  
Excision Repair ◽  
Dna Strand Breaks ◽  
Significant Loss ◽  
Human Cells ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Quiescent Cells ◽  
Dna Strand

ABSTRACT Genome stability in eukaryotic cells is maintained through efficient DNA damage repair pathways, which have to access and utilize chromatin as their natural template. Here we investigate the role of chromatin assembly factor 1 (CAF-1) and its interacting protein, PCNA, in the response of quiescent human cells to DNA double-strand breaks (DSBs). The expression of CAF-1 and PCNA is dramatically induced in quiescent cells upon the generation of DSBs by the radiomimetic drug bleocin (a bleomycin compound) or by ionizing radiation. This induction depends on DNA-PK. CAF-1 and PCNA are recruited to damaged chromatin undergoing DNA repair of single- and double-strand DNA breaks by the base excision repair and nonhomologous end-joining pathways, respectively, in the absence of extensive DNA synthesis. CAF-1 prepared from repair-proficient quiescent cells after induction by bleocin mediates nucleosome assembly in vitro. Depletion of CAF-1 by RNA interference in bleocin-treated quiescent cells in vivo results in a significant loss of cell viability and an accumulation of DSBs. These results support a novel and essential role for CAF-1 in the response of quiescent human cells to DSBs, possibly by reassembling chromatin following repair of DNA strand breaks.

scholarly journals Clinical response to deoxycoformycin in chronic lymphoid neoplasms and biochemical changes in circulating malignant cells in vivo

Blood ◽  
1988 ◽  
Vol 72 (6) ◽  
pp. 1884-1890
Author(s):  
AD Ho ◽  
K Ganeshaguru ◽  
WU Knauf ◽  
G Dietz ◽  
I Trede ◽  
...  
Keyword(s):  
Clinical Response ◽  
Dna Strand Breaks ◽  
Biochemical Changes ◽  
Leukemic Cells ◽  
Malignant Cells ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Lymphoid Neoplasms ◽  
Dna Strand

Deoxycoformycin (DCF), an adenosine deaminase (ADA) inhibitor, has been shown to be active in lymphoid neoplasms. The mechanism of cytotoxicity might involve accumulation of deoxyadenosine triphosphate (dATP), depletion of the nicotinamide adenine dinucleotide (NAD) and ATP pool, induction of double-stranded DNA strand breaks, or inhibition of S- adenosyl homocysteine hydrolase (SAH-hydrolase). We have investigated the biochemical changes in the circulating malignant cells of patients with chronic leukemia/lymphoma who were treated with DCF (4 mg/m2 weekly). Blood samples were taken from 17 patients with 60% or more circulating leukemic cells before, 4, 24, and 48 hours and five days after the first administration of DCF. Leukemic cells were separated and studied for changes in ADA, dATP, ATP, NAD, and SAH-hydrolase levels and DNA strand breaks and the data analyzed according to clinical response. Inhibition of ADA activity was found in all except one patient at 4 to 24 hours after the first administration of DCF. dATP started to accumulate at four hours, reached a maximum level between 24 and 48 hours, and returned to base values on the fifth day. Intracellular ATP and NAD levels were transiently reduced in some of the patients. However, no correlation between these changes and a clinical response could be found. DNA strand breaks could be studied in 13 patients. A significant increase in DNA breaks at 24 to 48 hours was found in six of the seven responders but only in one of the six nonresponders. At 24 hours, SAH-hydrolase levels were reduced in all seven responders studied, but only in two of the seven nonresponders. The difference in inhibition of SAH-hydrolase was statistically significant (P = .0023). These results suggest that DNA strand breaks and inhibition of SAH-hydrolase correlate with clinical response.

scholarly journals The role of poly(ADP-ribose) in the DNA damage signaling network

2005 ◽  
Vol 83 (3) ◽  
pp. 354-364 ◽  
Author(s):  
Maria Malanga ◽  
Felix R Althaus
Keyword(s):  
Dna Damage ◽  
Topoisomerase I ◽  
Dna Methyltransferase ◽  
Dna Strand Breaks ◽  
Sequence Motif ◽  
Dna Breaks ◽  
Strand Breaks ◽  
Covalent Interaction ◽  
Dna Damage Signaling ◽  
Dna Strand

DNA damage signaling is crucial for the maintenance of genome integrity. In higher eukaryotes a NAD+-dependent signal transduction mechanism has evolved to protect cells against the genome destabilizing effects of DNA strand breaks. The mechanism involves 2 nuclear enzymes that sense DNA strand breaks, poly(ADP-ribose) polymerase-1 and -2 (PARP-1 and PARP-2). When activated by DNA breaks, these PARPs use NAD+ to catalyze their automodification with negatively charged, long and branched ADP-ribose polymers. Through recruitment of specific proteins at the site of damage and regulation of their activities, these polymers may either directly participate in the repair process or coordinate repair through chromatin unfolding, cell cycle progression, and cell survival – cell death pathways. A number of proteins, including histones, DNA topoisomerases, DNA methyltransferase-1 as well as DNA damage repair and checkpoint proteins (p23, p21, DNA-PK, NF-kB, XRCC1, and others) can be targeted in this manner; the interaction involves a specific poly(ADP-ribose)-binding sequence motif of 20–26 amino acids in the target domains.Key words: PARP; polymer binding; non-covalent interaction; p53; DNA topoisomerase I.

scholarly journals Repair of DNA Strand Breaks by the Overlapping Functions of Lesion-Specific and Non-Lesion-Specific DNA 3′ Phosphatases

2001 ◽  
Vol 21 (21) ◽  
pp. 7191-7198 ◽  
Author(s):  
John R. Vance ◽  
Thomas E. Wilson
Keyword(s):  
Dna Damage ◽  
Oxidative Dna Damage ◽  
Synthetic Lethality ◽  
Dna Strand Breaks ◽  
Triple Mutant ◽  
Phosphatase Domain ◽  
Strand Breaks ◽  
Alternative Pathways ◽  
Processing Enzymes ◽  
Dna Strand

ABSTRACT In Saccharomyces cerevisiae, the apurinic/apyrimidinic (AP) endonucleases Apn1 and Apn2 act as alternative pathways for the removal of various 3′-terminal blocking lesions from DNA strand breaks and in the repair of abasic sites, which both result from oxidative DNA damage. Here we demonstrate that Tpp1, a homologue of the 3′ phosphatase domain of polynucleotide kinase, is a third member of this group of redundant 3′ processing enzymes. Unlike Apn1 and Apn2, Tpp1 is specific for the removal of 3′ phosphates at strand breaks and does not possess more general 3′ phosphodiesterase, exonuclease, or AP endonuclease activities. Deletion ofTPP1 in an apn1 apn2 mutant background dramatically increased the sensitivity of the double mutant to DNA damage caused by H2O2 and bleomycin but not to damage caused by methyl methanesulfonate. The triple mutant was also deficient in the repair of 3′ phosphate lesions left by Tdp1-mediated cleavage of camptothecin-stabilized Top1-DNA covalent complexes. Finally, the tpp1 apn1 apn2 triple mutation displayed synthetic lethality in combination with rad52, possibly implicating postreplication repair in the removal of unrepaired 3′-terminal lesions resulting from endogenous damage. Taken together, these results demonstrate a clear role for the lesion-specific enzyme, Tpp1, in the repair of a subset of DNA strand breaks.

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