Base excision repair in a network of defence and tolerance.
Institute of Cancer Research and Molecular Biology, Norwegian University of Science and Technology, N-7489 Trondheim, Norway.Carcinogenesis (impact factor: 5.7). 08/2001; 22(7):987-98. pp.987-98
Article: Early Steps in the DNA Base Excision Repair Pathway of a Fission Yeast Schizosaccharomyces pombe.[show abstract] [hide abstract]
ABSTRACT: DNA base excision repair (BER) accounts for maintaining genomic integrity by removing damaged bases that are generated endogenously or induced by genotoxic agents. In this paper, we describe the roles of enzymes functioning in the early steps of BER in fission yeast. Although BER is an evolutionarily conserved process, some unique features of the yeast repair pathway were revealed by genetic and biochemical approaches. AP sites generated by monofunctional DNA glycosylases are incised mainly by AP lyase activity of Nth1p, a sole bifunctional glycosylase in yeast, to leave a blocked 3' end. The major AP endonuclease Apn2p functions predominantly in removing the 3' block. Finally, a DNA polymerase fills the gap, and a DNA ligase seals the nick (Nth1p-dependent or short patch BER). Apn1p backs up Apn2p. In long patch BER, Rad2p endonuclease removes flap DNA containing a lesion after DNA synthesis. A UV-specific endonuclease Uve1p engages in an alternative pathway by nicking DNA on the 5' side of oxidative damage. Nucleotide excision repair and homologous recombination are involved in repair of BER intermediates including the AP site and single-strand break with the 3' block. Other enzymes working in 3' end processing are also discussed.Journal of nucleic acids 01/2010; 2010.
[show abstract] [hide abstract]
ABSTRACT: Lead plays a significant role in modern industry. This metal is related to a broad range of physiological, biochemical and behavioural dysfunctions. The genotoxic effects of lead have been studied both in animals and humans in in vitro systems but results were contradictory. The aim of this study was to investigate the association between DNA damage and occupational exposure to lead in workers. The study population consisted of 62 employees of metalworks exposed to lead in the southern region of Poland. The control group consisted of 26 office workers with no history of occupational exposure to lead. The concentration of lead (PbB) and zincprotoporphyrin (ZPP) in blood samples were measured. The DNA damage was analyzed in blood lymphocytes using alkaline comet assay. The level of DNA damage was determined as the percentage of DNA in the tail, tail length and tail moment. The lead exposure indicators were significantly higher in lead exposed group: PbB about 8.5 times and ZPP 3.3 times. Also, the percentage of DNA in the tail (60.3 ± 14 vs. 37.1 ± 17.6), comet tail length (86.9 ± 15.49 vs. 73.8 ± 19.12) and TM (57.8 ± 17.82 vs. 33.2 ± 19.13) were significantly higher in the study group when compared with the controls; however, the difference between the subgroups was only 5-10%. Years of lead exposure positively correlated with all comet assay parameters (R = 0.21-0.41). Both mean and current PbB and ZPP were correlated with tail DNA % and TM (R = 0.32; R = 0.33; R = 0.24; R = 0.26 and R = 0.34; R = 0.33; R = 0.28 and R = 0.28, respectively). This study shows that occupational exposure to lead is associated with DNA damage and confirmed that comet assay is a rapid, sensitive method suitable for biomonitoring studies.Annals of agricultural and environmental medicine: AAEM 12/2010; 17(2):231-6. · 2.31 Impact Factor
[show abstract] [hide abstract]
ABSTRACT: The liver plays a pivotal role in the metabolism of nutrients, drugs, hormones, and metabolic waste products, thereby maintaining body homeostasis. The liver undergoes substantial changes in structure and function within old age. Such changes are associated with significant impairment of many hepatic metabolic and detoxification activities, with implications for systemic aging and age-related disease. It has become clear, using rodent models as biological tools, that genetic instability in the form of gross DNA rearrangements or point mutations accumulate in the liver with age. DNA lesions, such as oxidized bases or persistent breaks, increase with age and correlate well with the presence of senescent hepatocytes. The level of DNA damage and/or mutation can be affected by changes in carcinogen activation, decreased ability to repair DNA, or a combination of these factors. This paper covers some of the DNA repair pathways affecting liver homeostasis with age using rodents as model systems.Current Gerontology and Geriatrics Research 01/2011; 2011:859415.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.