0000000000261891
AUTHOR
Ina Schulz
Oxidative DNA damage and mutations induced by a polar photosensitizer, Ro19-8022.
The oxidative DNA damage induced by the polar photosensitizer Ro19-8022 in the presence of light was studied and correlated with the associated mutagenicity. Both in isolated DNA and AS52 Chinese hamster ovary cells, photoexcited Ro19-8022 gave rise to a DNA damage profile that was similar to that caused by singlet oxygen: base modifications sensitive to the repair endonuclease Fpg protein, which according to high-performance liquid chromatography (HPLC) analysis were predominantly 8-hydroxyguanine (8-oxoG) residues, were generated in much higher yield than single-strand breaks, sites of base loss (AP sites) and oxidative pyrimidine modifications sensitive to endonuclease III. Fifty percent…
Study of the Mode and Efficiency of DNA Binding in the Damage Induced by Photoactivated Water Soluble Porphyrins
We have investigated the DNA binding interactions and in vitro photoactivated DNA damage induced by a neutral water soluble porphyrin derivative 5,10,15,20-tetrakis(2,4,6-trihydroxyphenyl)porphyrin (TTHPP) and its zinc derivative 5,10,15,20-tetrakis(2,4,6-trihydroxyphenyl)porphyrinato zinc(II) (Zn-TTHPP) upon visible light irradiation through various spectroscopic techniques and employing repair endonucleases. These porphyrin derivatives exhibited high affinity toward DNA through groove binding interactions as evidenced through the UV-vis absorption, emission, circular dichroism spectral and viscosity changes. Interestingly, the free base porphyrin derivative, TTHPP generated efficient sing…
Photoinduced DNA damage efficiency and cytotoxicity of novel viologen linked pyrene conjugates.
Novel viologen linked pyrene conjugates permeate cells efficiently and exhibit spacer length dependent DNA damage and cytotoxicity upon photoexcitation.
PO-002 Angiotensin II-induced hypertension increases the mutation frequency in the rat kidney
Introduction Epidemiological studies revealed an increased risk for kidney cancer in hypertensive patients. In many of these patients, the blood pressure regulating renin angiotensin aldosterone system (RAAS) is activated. A stimulated RAAS can lead to oxidative stress and DNA damage, as we have shown both in vitro and in animal models of hypertension. Here, we used a rat model to quantify mutations generated by 20 weeks of angiotensin II-infusion. Material and methods BigBlue+/- rats, which carry a transgenic lacI gene for mutation analysis, were treated with 0.4 mg angiotensin II/kg/day with the help of osmotic minipumps. Urinary samples were collected in week 15 by placing the rats into …
Influences of histone deacetylase inhibitors and resveratrol on DNA repair and chromatin compaction
Accessibility of DNA is a prerequisite for both DNA damage and repair. Therefore, the chromatin structure is expected to have major impact on both processes, with opposite consequences for the stability of the genome. To analyse the influence of chromatin compaction on the generation and repair of various types of DNA modifications, we modulated the global chromatin structure of AS52 Chinese hamster ovary cells and HeLa cells by treatment with either histone deacetylase inhibitors or resveratrol and measured the repair kinetics of (i) pyrimidine dimers induced by ultraviolet B, (ii) oxidised purines generated by photosensitisation and (iii) single-strand breaks induced by H2O2, using an alk…
Oxidative DNA base damage induced by singlet oxygen and photosensitization: recognition by repair endonucleases and mutagenicity.
We have analyzed the recognition by various repair endonucleases of DNA base modifications induced by three oxidants, viz. [4-(tert-butyldioxycarbonyl)benzyl]triethylammonium chloride (BCBT), a photochemical source of tert-butoxyl radicals, disodium salt of 1,4-etheno-2,3-benzodioxin-1,4-dipropanoic acid (NDPO(2)), a chemical source of singlet oxygen, and riboflavin, a type-I photosensitizer. The base modifications induced by BCBT, which were previously shown to be mostly 7,8-dihydro-8-oxoguanine (8-oxoGua) residues, were recognized by Fpg and Ogg1 proteins, but not by endonuclease IIII, Ntg1 and Ntg2 proteins. In the case of singlet oxygen induced damage, 8-oxoGua accounted for only 35% of…
tert-Butoxyl radicals generate mainly 7,8-dihydro-8-oxoguanine in DNA.
Abstract Like hydroxyl radicals, alkoxyl radicals have been implicated in the generation of cellular oxidative DNA damage under physiological conditions; however, their genotoxic potential has not yet been established. We have analyzed the DNA damage induced by a photochemical source of tert- butoxyl radicals, the water soluble peroxy ester [4-( tert -butyldioxycarbonyl)benzyl]triethylammonium chloride (BCBT), using various repair endonucleases as probes. The irradiation (UV 360 ) of BCBT in the presence of bacteriophage PM2 DNA was found to generate a DNA damage profile that consisted mostly of base modifications sensitive to the repair endonuclease Fpg protein. Approximately 90% of the mo…
Mouse CSB protein is important for gene expression in the presence of a single-strand break in the non-transcribed DNA strand.
CSB protein is required for strand-specific repair of bulky DNA lesions in transcribed genes and mediates transcription recovery after exposure to DNA-damaging agents. We enzymatically generated DNA single-strand breaks (SSBs) with 3'-OH and 5'-phosphate termini in defined positions of a plasmid-borne gene and measured their effect on transcription in cell lines with different statuses of the Csb gene. A single SSB in the transcribed region of the gene caused significant decrease of gene expression. In all tested cell lines of mouse and human origin, a SSB in the transcribed DNA strand was less harmful for gene expression than a SSB situated in the opposing DNA strand. CSB deficiency exhibi…