Molecular mechanisms of ultraviolet radiation-induced DNA damage and repair

Laboratory of Photobiology and Molecular Microbiology, Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi 221005, India.
Journal of nucleic acids 01/2010; 2010:592980. DOI: 10.4061/2010/592980
Source: PubMed


DNA is one of the prime molecules, and its stability is of utmost importance for proper functioning and existence of all living systems. Genotoxic chemicals and radiations exert adverse effects on genome stability. Ultraviolet radiation (UVR) (mainly UV-B: 280-315 nm) is one of the powerful agents that can alter the normal state of life by inducing a variety of mutagenic and cytotoxic DNA lesions such as cyclobutane-pyrimidine dimers (CPDs), 6-4 photoproducts (6-4PPs), and their Dewar valence isomers as well as DNA strand breaks by interfering the genome integrity. To counteract these lesions, organisms have developed a number of highly conserved repair mechanisms such as photoreactivation, base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Additionally, double-strand break repair (by homologous recombination and nonhomologous end joining), SOS response, cell-cycle checkpoints, and programmed cell death (apoptosis) are also operative in various organisms with the expense of specific gene products. This review deals with UV-induced alterations in DNA and its maintenance by various repair mechanisms.

Download full-text


Available from: Rajeshwar P Sinha, Oct 04, 2015
1 Follower
42 Reads
  • Source
    • "B) Os dois principais fotoprodutos induzidos pela absorção de luz UV pela molécula de DNA são os dímeros de pirimidina ciclobutano (CPD) e os fotoprodutos 6-4 pirimidina-pirimidona (6-4PPs). Estruturas moleculares foram adaptadas da revisão de Rastogi, et al 2010. C) A replicação de dímeros pode resultar em mutações pontuais. "
    06/2015; 14(1):6-16. DOI:10.7594/revbio.14.01.02
  • Source
    • "The DNA repair of UVA-induced DNA damage occurs through three main mechanisms: (1) Photoreactivation, which involves the direct monomerization of CPDs and 6–4PPs by the action of photolyases enzymes in the presence of UVA/visible light; (2) Nucleotide Excision Repair (NER) which is critically important in the repair of UV-induced DNA lesion and is one of the most versatile and flexible repair systems found in most organisms; and (3) Base Excision Repair (BER) which acts on small DNA lesions such as oxidized bases, abasic sites and DNA single-strand breaks (Cadet et al., 2005; Rastogi et al., 2010). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The increased incidence of solar ultraviolet radiation (UV) due to ozone depletion has been affecting both terrestrial and aquatic ecosystems and it may help to explain the enigmatic decline of amphibian populations in specific localities. In this work, influential events concerning the Antarctic ozone hole were identified in a dataset containing 35 years of ozone measurements over southern Brazil. The effects of environmental doses of UVB and UVA radiation were addressed on the morphology and development of Hypsiboas pulchellus tadpole (Anura: Hylidae), as well as on the induction of malformation after the conclusion of metamorphosis. These analyzes were complemented by the detection of micronucleus formation in blood cells. 72 ozone depletion events were identified from 1979 to 2013. Surprisingly, their yearly frequency increased three-fold during the last 17 years. The results clearly show that H. pulchellus tadpole are much more sensitive to UVB than UVA light, which reduces their survival and developmental rates. Additionally, the rates of micronucleus formation by UVB were considerably higher compared to UVA even after the activation of photolyases enzymes by a further photoreactivation treatment. Consequently, a higher occurrence of malformation was observed in UVB-irradiated individuals. These results demonstrate the severe genotoxic impact of UVB radiation on this treefrog species and its importance for further studies aimed to assess the impact of the increased levels of solar UVB radiation on declining species of the Hylidae family. Copyright © 2015 Elsevier Inc. All rights reserved.
    Ecotoxicology and Environmental Safety 05/2015; 118:190-198. DOI:10.1016/j.ecoenv.2015.04.029 · 2.76 Impact Factor
    • "In conclusion, both trophozoites and encysting cells are affected by UV treatment but replicating Giardia parasites are more resistant to UV treatment. UV treatment produces oxidized bases and single-and doublestrand breaks (DSB) in the genomic DNA of living organisms (Georgakilas et al., 2013; Rastogi et al., 2010). To study if UV treatment induces DSB in Giardia, which can result in cell growth arrest Table 1 Growth and establishment of in vitro cultures after exposure to UV irradiation. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The response to ultraviolet light (UV) radiation, a natural stressor to the intestinal protozoan parasite Giardia intestinalis, was studied to deepen the understanding of how the surrounding environment affects the parasite during transmission. UV radiation at 10 mJ/cm(2) kills Giardia cysts effectively whereas trophozoites and encysting parasites can recover from UV treatment at 100 mJ/cm(2) and 50 mJ/cm(2) respectively. Staining for phosphorylated histone H2A showed that UV treatment induces double-stranded DNA breaks and flow cytometry analyses revealed that UV treatment of trophozoites induces DNA replication arrest. Active DNA replication coupled to DNA repair could be an explanation to why UV light does not kill trophozoites and encysting cells as efficiently as the non-replicating cysts. We also examined UV-induced gene expression responses in both trophozoites and cysts using RNA sequencing (RNA seq). UV radiation induces small overall changes in gene expression in Giardia but cysts show a stronger response than trophozoites. Heat shock proteins, kinesins and Nek kinases are up-regulated, whereas alpha-giardins and histones are down-regulated in UV treated trophozoites. Expression of variable surface proteins (VSPs) is changed in both trophozoites and cysts. Our data show that Giardia cysts have limited ability to repair UV-induced damage and this may have implications for drinking- and waste-water treatment when setting criteria for the use of UV disinfection to ensure safe water. Copyright © 2015 Elsevier Inc. All rights reserved.
    Experimental Parasitology 03/2015; 154. DOI:10.1016/j.exppara.2015.03.024 · 1.64 Impact Factor
Show more