Comparison of initial yields of DNA-to-protein crosslinks and single-strand breaks induced in cultured human cells by far- and near-ultraviolet light, blue light and X-rays

Peak, Jennifer G.; Peak, Meyrick J.

doi:10.1016/0027-5107(91)90121-4

Cited by 106 publications

(36 citation statements)

References 21 publications

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“…Although Xirradiation also generates ROS, the amounts of DNA-protein crosslinks in the X-irradiated nuclei at 10 Gy were considerably less than those in the UVA-irradiated nuclei at 300 kJ/m 2 . X-irradiation produces much more DNA strand breaks than DNA-protein crosslinks and produces much more DNA strand breaks than does UVA radiation [11]. The present results showed that there was no inhibitory effect on the Mg 2+ -dependent transition of chromatin sturcture after X-irradiation.…”

Section: Discussionmentioning

confidence: 43%

“…Several types of DNA damage, such as single-and doublestrand breaks [17,20,21], base modification [10,12,16], and DNA-protein crosslinks [11,14], were induced in DNA by UVA radiation. It is thought that such DNA damage is produced by ROS genereated by UVA radiation [21].…”

Section: Discussionmentioning

confidence: 99%

“…Long-wave ultraviolet radiation, ultraviolet A (UVA) radiation, of which the wavelength is from 320 to 400 nm, constitutes more than 90% of terrestrial UV solar energy on the earth's surface. UVA radiation causes cell death and mutation, although a much higher fluence of UVA raditation is necessary to induce these biological responses than that of ultraviolet B (UVB) radiation, from 290 to 320 nm, and ultraviolet C (UVC) radiation, from 200 to 290 nm [17,20,21].UVA radiation has been reported to induce several types of DNA damage, such as strand breaks [10,12,16], base modification [8,9,15] and DNA-protein crosslinks [11,14]. Because UVA rays are not directly absorbed by DNA and their biological effects depend strongly on the presence of oxygen, UV rays of this wavelength probably exert their effects through indirect mechanisms in which endogenous photosensitizers, such as NADH/NADPH and riboflavin, absorb UVA photons to generate reactive oxygen species (ROS) [7,19,21].…”

mentioning

confidence: 99%

“…UVA radiation has been reported to induce several types of DNA damage, such as strand breaks [10,12,16], base modification [8,9,15] and DNA-protein crosslinks [11,14]. Because UVA rays are not directly absorbed by DNA and their biological effects depend strongly on the presence of oxygen, UV rays of this wavelength probably exert their effects through indirect mechanisms in which endogenous photosensitizers, such as NADH/NADPH and riboflavin, absorb UVA photons to generate reactive oxygen species (ROS) [7,19,21].…”

mentioning

confidence: 99%

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Inhibitory Effects of Long-Wave Ultraviolet Radiation of Isolated Chicken Liver Nuclei on the Mg2+-Dependent Transition of Chromatin Structure.

Arai

Nakanishi

Hayashi

2000

The Journal of Veterinary Medical Science

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ABSTRACT. Since the turbidity of nuclear suspensions is known to be correlated with the nuclear morphology, the effects of long-wave ultraviolet (UVA) radiation on Mg 2+ -dependent structural transition of chromatin in isolated chicken liver nuclei were monitored by measuring the relative turbidity of nuclear suspensions. UVA radiation of the nuclei inhibited the Mg 2+ -dependent change in relative turbidity of nuclear suspensions in a UVA dose-dependent manner under aerobic conditions but not under N 2 conditions. No inhibitrory effect of UVA radiation on the change in relative turbidity was observed in the presence of 50 mM NaN 3 , which scavenges singlet oxygen ( 1 O 2 ) and hydroxyl radicals (•OH). In contrast, 100 mM dimethyl sulfoxide, which primarily scavenges •OH, did not show the inhibitory effect of UVA radiation. The amounts of DNA-protein crosslinks increased with UVA dose under aerobic conditions but not under N 2 conditions. The present study showed that UVA radiation of isolated nuclei inhibited the Mg 2+ -dependent unfolding of condensed chromatin and that 1 O 2 is likely to be involved in this process. Furthermore, the formation of DNA-protein crosslinks may contribute to the inhibition.KEY WORDS: chicken liver nuclei, chromatin structure, Mg 2+ -dependent transition, singlet oxygen, UVA radiation.J. Vet. Med. Sci. 62(8): 861-865, 2000 In animals, prolonged sunlight exposure is associated with various pathological states, including erythemia, cataract, skin aging, and cancer. Long-wave ultraviolet radiation, ultraviolet A (UVA) radiation, of which the wavelength is from 320 to 400 nm, constitutes more than 90% of terrestrial UV solar energy on the earth's surface. UVA radiation causes cell death and mutation, although a much higher fluence of UVA raditation is necessary to induce these biological responses than that of ultraviolet B (UVB) radiation, from 290 to 320 nm, and ultraviolet C (UVC) radiation, from 200 to 290 nm [17,20,21].UVA radiation has been reported to induce several types of DNA damage, such as strand breaks [10,12,16], base modification [8,9,15] and DNA-protein crosslinks [11,14]. Because UVA rays are not directly absorbed by DNA and their biological effects depend strongly on the presence of oxygen, UV rays of this wavelength probably exert their effects through indirect mechanisms in which endogenous photosensitizers, such as NADH/NADPH and riboflavin, absorb UVA photons to generate reactive oxygen species (ROS) [7,19,21]. UVA radiation has also been shown to inhibit several biological processes, such as transcription in cultured human fibroblasts [4] and in isolated chicken liver nuclei [2], although few studies have focused on the effects of UVA radiation-induced DNA damage on biological processes. In the eukaryotic cell nucleus, DNA is complexed with histones and other proteins to form several hierarchical chromatin structures. It has been suggested that structural transition of chromatin from a compact inactive structure to a more extended open conformation is a prerequ...

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Section: Discussionmentioning

confidence: 43%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Inhibitory Effects of Long-Wave Ultraviolet Radiation of Isolated Chicken Liver Nuclei on the Mg2+-Dependent Transition of Chromatin Structure.

Arai

Nakanishi

Hayashi

2000

The Journal of Veterinary Medical Science

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“…Ultraviolet (UV) radiation can increase the melanization and the proliferation of melanocytes by acting on melanocytes directly (1,2) or indirectly through the release of keratinocyte derived factors (3). UV radiation also induces the formation of reactive oxygen species (ROS) in the skin; these ROS assist melanin biosynthesis and damage DNA, and then may induce the proliferation and/or apoptosis of melanocytes (4)(5)(6). H 2 O 2 , which is one of the ROS generated, causes an increase in the level of tyrosinase mRNA (7).…”

Section: Introductionmentioning

confidence: 99%

Oligomeric proanthocyanidins from grape seeds effectively inhibit ultraviolet-induced melanogenesis of human melanocytes in vitro

Ma²,

Li³

et al. 1998

Int J Mol Med

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Abstract. The oligomeric proanthocyanidins (OPCs) from grape seeds are expected to be novel and potent anti-oxidants that more effectively protect skin cells against oxidative stress. UV-induced oxidative stress is considered to promote melanogenesis and serious skin damage. However, the effect of OPCs on UV-induced melanogenesis is still unknown. To investigate the role of OPCs on mleanogenesis of human melanocytes with UV exposure, we evaluated the effects of melanogenesis, cellular cycle, intracellular reactive oxidative species (ROS) level and protein level of melanogenic enzyme in cultured human melanocytes following UV-irradiation by OPCs. After treatment with different doses of OPCs or L-ascorbic acid, normal human melanocytes (NHM) were irradiated by 15 mJ/cm 2 UV light. Then, cellular melanin content, activity of tyrosinase were examined. Moreover, the protein analysis of tyrosinase, tyrosinase related protein 1 (TRP1), and tyrosinase related protein 2 (TRP2) were observed by Western blotting. Levels of UV-induced ROS in melanocytes and the responses of cell cycle were also examined by immunofluorescence techniques. This study demonstrated that OPCs, significantly inhibited the cell dead induced by UV irradiation in a dose-dependent manner and OPCs alone, has no effects on melanogenesis of NHM, however, it significantly inhibited UV-induced melanogenesis in a dose-dependent manner. The UV-induced intracellular ROS enhancement was also prevented by addition of OPCs in a dose-dependent manner. Meanwhile, OPCs also inhibited the extent of G1 arrest that was induced by UV exposure. OPCs can decrease the protein level of tyrosinase, TRP1 and TRP2 in UVirradiated NHM. Thus, OPCs have potential effects of photoprotection on human melanocytes by improving cell viability, scavenging intracellular ROS, adjusting cell cycle and inhibiting protein expression of melanogenic enzymes. IntroductionMelanin plays an important protective role against ultraviolet irradiation, but overproduction and accumulation of melanin could create serious skin problems such as freckles, age pigment, and melasma. Thus, the inhibition of melanogenesis has been the focus on medicinal and cosmetic treatments for skin depigmenting and lightening. Ultraviolet (UV) radiation can increase the melanization and the proliferation of melanocytes by acting on melanocytes directly (1,2) or indirectly through the release of keratinocyte derived factors (3). UV radiation also induces the formation of reactive oxygen species (ROS) in the skin; these ROS assist melanin biosynthesis and damage DNA, and then may induce the proliferation and/or apoptosis of melanocytes (4-6). H 2 O 2 , which is one of the ROS generated, causes an increase in the level of tyrosinase mRNA (7). The dose of UV irradiation seems to regulate and control the UV-induced proliferation of melanocytes. Quevedo et al (8) reported that UV radiation induced proliferation and melanogenesis of melanocytes was reduced by the topical application of antioxidants such as vitamins C and E to...

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Standard fluorescent imaging of live cells is highly genotoxic

Wood

Weingeist

et al. 2013

Cytometry Pt A

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Fluorescence microscopy is commonly used for imaging live mammalian cells. Here, we describe studies aimed at revealing the potential genotoxic effects of standard fluorescence microscopy. To assess DNA damage, a high throughput platform for single cell gel electrophoresis is used (e.g., the CometChip). Light emitted by three standard filters was studied: a) violet light [340–380 nm], used to excite DAPI and other blue fluorophores, b) blue light [460–500 nm] commonly used to image GFP and Calcein AM, and c) green light [528–553], useful for imaging red fluorophores. Results show that exposure of samples to light during imaging is indeed genotoxic even when the selected wavelengths are outside the range known to induce significant levels. Shorter excitation wavelengths and longer irradiation times lead to higher levels of DNA damage. We have also measured DNA damage in cells expressing enhanced green fluorescent protein (GFP) or stained with Calcein AM, a widely used green fluorophore. Data show that Calcein AM leads to a synergistic increase in the levels of DNA damage and that even cells that are not being directly imaged sustain significant DNA damage from exposure to indirect light. The nature of light-induced DNA damage during imaging was assessed using the Fpg glycosylase, an enzyme that enables quantification of oxidative DNA damage. Oxidative damage was evident in cells exposed to violet light. Furthermore the Fpg glycosylase revealed the presence of oxidative DNA damage in blue-light exposed cells for which DNA damage was not detected using standard analysis conditions. Taken together, the results of these studies call attention to the potential confounding effects of DNA damage induced by standard imaging conditions, and identify wavelength, exposure time and fluorophore as parameters that can be modulated to reduce light-induced DNA damage.

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Comparison of initial yields of DNA-to-protein crosslinks and single-strand breaks induced in cultured human cells by far- and near-ultraviolet light, blue light and X-rays

Cited by 106 publications

References 21 publications

Inhibitory Effects of Long-Wave Ultraviolet Radiation of Isolated Chicken Liver Nuclei on the Mg2+-Dependent Transition of Chromatin Structure.

Inhibitory Effects of Long-Wave Ultraviolet Radiation of Isolated Chicken Liver Nuclei on the Mg2+-Dependent Transition of Chromatin Structure.

Oligomeric proanthocyanidins from grape seeds effectively inhibit ultraviolet-induced melanogenesis of human melanocytes in vitro

Standard fluorescent imaging of live cells is highly genotoxic

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