scholarly journals Expression of the HPV18/E6 oncoprotein induces DNA damage

2017 ◽  
Author(s):  
Elva I. Cortés Gutiérrez ◽  
Catalina Garcí­a-Vielma ◽  
Adriana Aguilar-Lemarroy ◽  
Veronica Vallejo-Ruí­z ◽  
Patricia Piña-Sánchez ◽  
...  
Keyword(s):  
Dna Damage ◽  
Hela Cells ◽  
Dna Hybridization ◽  
Dna Breaks ◽  
Dna Breakage ◽  
Hpv E6 ◽  
E6 Oncoprotein ◽  
Normal Expression ◽  
Hpv18 E6

This study investigated possible variations in DNA damage in HeLa cells with silenced expression of the HPV/E6 oncogene compared with HeLa cells with normal expression of the E6 oncogene using the DNA breakage detection-fluorescence in situ hybridization (DBD-FISH) technique and a whole human genome DNA probe. The variable levels of DNA breaks present were measured quantitatively using image analysis after whole-genome DNA hybridization. HeLa cells with silenced expression of the HPV18/E6 oncogene showed a significant decrease in DNA damage compared with parental cells with normal expression of the E6 oncogene. These results were confirmed by alkaline comet assay. In conclusion, we demonstrated a decrease in DNA damage in HeLa clones associated with low expression of the HPV/E6 oncogene. The significance of this decrease regarding the HPV life cycle and carcinogenesis requires further exploration.

Evaluation of oxidative DNA damage in pigeon erythrocytes using DNA breakage detection-fluorescence in situ hybridization (DBD-FISH)

2019 ◽  
Vol 94 (8) ◽  
pp. 600-605 ◽  
Author(s):  
E. I. Cortés-Gutiérrez ◽  
J. A. García-Salas ◽  
M. I. Dávila-Rodríguez ◽  
J. P. Ceyca-Contreras ◽  
E. G. González-Ramírez
Keyword(s):  
Dna Damage ◽  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Oxidative Dna Damage ◽  
Dna Breakage

scholarly journals Differences in DNA Fragmentation following Transient Cerebral or Decapitation Ischemia in Rats

1995 ◽  
Vol 15 (5) ◽  
pp. 728-737 ◽  
Author(s):  
J. P. MacManus ◽  
I. E. Hill ◽  
E. Preston ◽  
I. Rasquinha ◽  
T. Walker ◽  
...  
Keyword(s):  
Dna Damage ◽  
Gel Electrophoresis ◽  
Time Course ◽  
Apoptotic Cell ◽  
Forebrain Ischemia ◽  
Dna Breaks ◽  
Double Labeling ◽  
Ca1 Region ◽  
Cell Death Pathway

The time course of appearance of cells with DNA damage was studied in rats following transient severe forebrain ischemia. This DNA damage could be detected by in situ end-labeling on brain sections. The breaks in DNA appeared selectively by day 1 in the striatum and later in the CA1 region of the hippocampus. It was possible by double labeling to show that there was no DNA damage in astrocytes. The DNA breaks consisted of laddered DNA fragments indicative of an ordered apoptotic type of internucleosomal cleavage, which persisted without smearing for up to 7 days of reperfusion. In contrast, the DNA breaks following ischemia induced by decapitation were random and, after gel electrophoresis, consisted of smeared fragments of multiple sizes. There was some early regional cellular death, restricted to the dentate of the hippocampus, prior to the pannecrotic degeneration. It is concluded that transient forebrain ischemia leads to a type of neuronal destruction that is not random necrosis but that shares some component of the apoptotic cell death pathway.

scholarly journals Effects of quin2 acetoxymethyl ester on H2O2-induced DNA single-strand breakage in mammalian cells: H2O2-concentration-dependent inhibition of damage and additive protective effect with the hydroxyl-radical scavenger dimethyl sulphoxide

1995 ◽  
Vol 305 (1) ◽  
pp. 181-185 ◽  
Author(s):  
B E Sandström
Keyword(s):  
Dna Damage ◽  
Mammalian Cells ◽  
Cultured Cells ◽  
Single Strand ◽  
Dimethyl Sulphoxide ◽  
Radical Scavenger ◽  
Dna Breaks ◽  
Acetoxymethyl Ester ◽  
Dna Breakage ◽  
Strand Breakage

The cell-membrane-permeable calcium probe quin2 acetoxymethyl ester (quin2 AM) was ineffective, in comparison with o-phenanthroline, in protecting cells against H2O2-induced DNA single-strand breakage at H2O2 concentrations of about, and higher than, 0.5 mM. The present study shows that quin2 actually potentiated intracellular DNA damage at high H2O2 concentrations. H2O2-induced DNA breakage appeared within 5 min after exposure, and quin2 affected the induction of DNA breaks at both 0 degree C and 37 degrees C. Aurintricarboxylic acid, an endonuclease inhibitor, or a decrease in extracellular Ca2+, did not reduce DNA damage. These facts strongly suggest that the breaks were not produced by a Ca(2+)-dependent nuclease. We showed previously that, in the presence of Fe3+ and H2O2, quin2 strongly potentiated the formation of oxidizing species as well as plasmid DNA breakage, and, as could be expected for a transition-metal chelator, quin2 inhibited the Fenton reaction when Cu2+ was tested instead of Fe3+ [Sandström, Granström and Marklund (1994) Free Radicals Biol. Med. 16, 177-185]. In the present work with cultured cells, titration with quin2 AM showed that, despite the fact that Cu2+ has a three-to-four-orders-of-magnitude higher affinity for quin2 than has Fe3+, both inhibition and potentiation of H2O2-induced DNA damage occurred at quin2 AM concentrations of about 100 nM. Thus inhibition appeared not to involve Cu2+. The combination of quin2 AM and dimethyl sulphoxide (DMSO) gave an additive effect on H2O2-induced DNA damage compared with the effect of quin2 AM or DMSO alone, whereas the combination of o-phenanthroline and DMSO gave about the same effect as o-phenanthroline alone. In conclusion, our results do not support a role for Ca2+ in the inhibiting effect of quin2 on H2O2-induced DNA damage. Instead, it is likely that inhibition and potentiation by quin2 involves interaction with Fe ions.

scholarly journals STRIDE—a fluorescence method for direct, specific in situ detection of individual single- or double-strand DNA breaks in fixed cells

2019 ◽  
Vol 48 (3) ◽  
pp. e14-e14 ◽  
Author(s):  
Magdalena M Kordon ◽  
Mirosław Zarębski ◽  
Kamil Solarczyk ◽  
Hanhui Ma ◽  
Thoru Pederson ◽  
...  
Keyword(s):  
Dna Damage ◽  
Single Cells ◽  
Dna Lesions ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Dna Breaks ◽  
Damage Site ◽  
Double Strand Dna Breaks ◽  
In Situ Detection ◽  
Double Strand Dna

Abstract We here describe a technique termed STRIDE (SensiTive Recognition of Individual DNA Ends), which enables highly sensitive, specific, direct in situ detection of single- or double-strand DNA breaks (sSTRIDE or dSTRIDE), in nuclei of single cells, using fluorescence microscopy. The sensitivity of STRIDE was tested using a specially developed CRISPR/Cas9 DNA damage induction system, capable of inducing small clusters or individual single- or double-strand breaks. STRIDE exhibits significantly higher sensitivity and specificity of detection of DNA breaks than the commonly used terminal deoxynucleotidyl transferase dUTP nick-end labeling assay or methods based on monitoring of recruitment of repair proteins or histone modifications at the damage site (e.g. γH2AX). Even individual genome site-specific DNA double-strand cuts induced by CRISPR/Cas9, as well as individual single-strand DNA scissions induced by the nickase version of Cas9, can be detected by STRIDE and precisely localized within the cell nucleus. We further show that STRIDE can detect low-level spontaneous DNA damage, including age-related DNA lesions, DNA breaks induced by several agents (bleomycin, doxorubicin, topotecan, hydrogen peroxide, UV, photosensitized reactions) and fragmentation of DNA in human spermatozoa. The STRIDE methods are potentially useful in studies of mechanisms of DNA damage induction and repair in cell lines and primary cultures, including cells with impaired repair mechanisms.

Antiproliferative Effects of AAV-Delivered CRISPR/Cas9-Based Degradation of the HPV18-E6 Gene in HeLa Cells

2021 ◽  
Author(s):  
Zahra Noroozi ◽  
Mehdi Shamsara ◽  
Elahe Valipour ◽  
Sahar Esfandyari ◽  
Alireza Ehghaghi ◽  
...  
Keyword(s):  
Hela Cells ◽  
P53 Protein ◽  
Annexin V ◽  
Antiproliferative Effects ◽  
Cervical Cancers ◽  
Hpv E6 ◽  
E6 Gene ◽  
Therapeutic Benefits ◽  
Hpv18 E6 ◽  
Infected Cells

Abstract Human papillomavirus infections are associated with most cervical cancers, which are the fourth most common cancer in women. HPV-E6 protein binds to protein p53 and inhibits its function, leading to the switching of normal cells toward cancer cells. Here, we disrupted the HPV-E6 gene and investigated its effects on the proliferation and apoptosis of HeLa cells. The HPV18-E6 gene was targeted with two designed sgRNAs cloned into an AAV-CRISPR-based plasmid. The AAV-E6-CRISPR/Cas9 virions were prepared and titrated in HEK293t cells. The cleavage created in the HPV-E6 gene was detected using the T7E1 assay. Cell cycle profiling, MTT assay, and annexin V/PI staining were performed. Also, the p53 protein level was measured by Western blotting. Our data showed that disruption of the HPV-E6 gene led to increased cell apoptosis and decreased cell proliferation. A significant accumulation of infected cells in sub-G1 phase was observed in the cell profiling assay. Also, HPV-E6 gene disruption resulted in a significant increase in the level of P53 protein. Our findings indicated that AAV-mediated delivery of CRISPR/Cas9 can effectively target the HPV-E6 gene in HeLa cells, and its antiproliferative effects may provide therapeutic benefits of local administration of this gene-editing system for HPV-related cervical cancers.

scholarly journals Analysis of DNA breaks, DNA damage response, and apoptosis produced by high NaCl

2008 ◽  
Vol 295 (6) ◽  
pp. F1678-F1688 ◽  
Author(s):  
Natalia I. Dmitrieva ◽  
Maurice B. Burg
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Response ◽  
Hela Cells ◽  
Cell Types ◽  
Dna Breaks ◽  
Main Subject ◽  
Mrn Complex ◽  
Damage Response

We previously reported that, both in cell culture and in the renal inner medulla in vivo, elevating NaCl increased the number of DNA breaks, which persisted as long as NaCl remained high but were rapidly repaired when NaCl was lowered. Furthermore, those breaks did not induce the DNA repair protein γH2AX or cause activation of the MRN (Mre11, Rad50, Nbs1) complex. In contrast, others recently reported that high NaCl does induce γH2AX and MRN complex formation and concluded that these activities are associated with repair of the DNA (Sheen MR, Kim SW, Jung JY, Ahn JY, Rhee JG, Kwon HM, Woo SK. Am J Physiol Renal Physiol 291: F1014–F1020, 2006). The purpose of the present studies was to resolve the disparity. The important difference is that HeLa cells, which were the main subject of the later report, are much less tolerant of high NaCl than are the mIMCD3 cells, which were our main subject. mIMCD3 cells survive levels of NaCl that kill HeLa cells by apoptosis. Here we demonstrate that in both cell types raising NaCl to a level that the cells survive (higher for mIMCD3 than HeLa) increases DNA breaks without inducing γH2AX or activating the MRN complex and that the DNA breaks persist as long as NaCl remains elevated, but are rapidly repaired when it is lowered. Importantly, in both cell types, raising NaCl further to cause apoptosis activates these DNA damage response proteins and greatly fragments DNA, associated with cell death. We conclude that γH2AX induction and MRN activation in response to high NaCl are associated with apoptosis, not DNA repair.

scholarly journals Characterization of DNA Damage in Yeast Apoptosis Induced by Hydrogen Peroxide, Acetic Acid, and Hyperosmotic Shock

2006 ◽  
Vol 17 (10) ◽  
pp. 4584-4591 ◽  
Author(s):  
Gabriela F. Ribeiro ◽  
Manuela Côrte-Real ◽  
Björn Johansson
Keyword(s):  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Acetic Acid ◽  
Dna Fragmentation ◽  
Tunel Staining ◽  
Chromosomal Dna ◽  
Dna Breaks ◽  
Hyperosmotic Shock ◽  
Double Strand Dna Breaks

Saccharomyces cerevisiae has been reported to die, under certain conditions, from programmed cell death with apoptotic markers. One of the most important markers is chromosomal DNA fragmentation as indicated by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. We found TUNEL staining in S. cerevisiae to be a consequence of both single- and double-strand DNA breaks, whereas in situ ligation specifically stained double-strand DNA breaks. Cells treated with hydrogen peroxide or acetic acid staining positively for TUNEL assay stained negatively for in situ ligation, indicating that DNA damage in both cases mainly consists of single-strand DNA breaks. Pulsed field gel electrophoresis of chromosomal DNA from cells dying from hydrogen peroxide, acetic acid, or hyperosmotic shock revealed DNA breakdown into fragments of several hundred kilobases, consistent with the higher order chromatin degradation preceding DNA laddering in apoptotic mammalian cells. DNA fragmentation was associated with death by treatment with 10 mM hydrogen peroxide but not 150 mM and was absent if cells were fixed with formaldehyde to eliminate enzyme activity before hydrogen peroxide treatment. These observations are consistent with a process that, like mammalian apoptosis, is enzyme dependent, degrades chromosomal DNA, and is activated only at low intensity of death stimuli.

Electron Microscopy of Mycoplasma Pneumoniae

1971 ◽  
Vol 29 ◽  
pp. 258-259 ◽  
Author(s):  
E. S. Boatman ◽  
G. E. Kenny
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Growth Phase ◽  
Hela Cells ◽  
Sulfonic Acid ◽  
Gamma Globulin ◽  
Horse Serum ◽  
Morphological Aspects ◽  
The Family

Information concerning the morphology and replication of organism of the family Mycoplasmataceae remains, despite over 70 years of study, highly controversial. Due to their small size observations by light microscopy have not been rewarding. Furthermore, not only are these organisms extremely pleomorphic but their morphology also changes according to growth phase. This study deals with the morphological aspects of M. pneumoniae strain 3546 in relation to growth, interaction with HeLa cells and possible mechanisms of replication.The organisms were grown aerobically at 37°C in a soy peptone yeast dialysate medium supplemented with 12% gamma-globulin free horse serum. The medium was buffered at pH 7.3 with TES [N-tris (hyroxymethyl) methyl-2-aminoethane sulfonic acid] at 10mM concentration. The inoculum, an actively growing culture, was filtered through a 0.5 μm polycarbonate “nuclepore” filter to prevent transfer of all but the smallest aggregates. Growth was assessed at specific periods by colony counts and 800 ml samples of organisms were fixed in situ with 2.5% glutaraldehyde for 3 hrs. at 4°C. Washed cells for sectioning were post-fixed in 0.8% OSO4 in veronal-acetate buffer pH 6.1 for 1 hr. at 21°C. HeLa cells were infected with a filtered inoculum of M. pneumoniae and incubated for 9 days in Leighton tubes with coverslips. The cells were then removed and processed for electron microscopy.

A new method for the in situ assay of α-glucosidase activity and inhibitor screening through an enzyme substrate-mediated DNA hybridization chain reaction

2019 ◽  
Vol 43 (24) ◽  
pp. 9458-9465
Author(s):  
Xiquan Yue ◽  
Lihong Su ◽  
Xu Chen ◽  
Junfeng Liu ◽  
Longpo Zheng ◽  
...  
Keyword(s):  
Small Molecule ◽  
Dna Hybridization ◽  
New Method ◽  
Hybridization Chain Reaction ◽  
Chain Reaction ◽  
Inhibitor Screening ◽  
Glucosidase Activity ◽  
Enzyme Substrate ◽  
In Situ Assay

The strategy is based on small molecule-mediated hybridization chain reaction.

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