title: 8-Oxoguanine DNA glycosylase 1 (OGG1) from the copepod Tigriopus japonicus: molecular characterization and its expression in response to UV-B and heavy metals.
abstract: 8-Oxoguanine DNA glycosylase 1 (EC 3.2.2.23) is encoded by OGG1 gene and plays a key role in removing 8-oxo-7,8-dihydroguanine (8-oxoG) base in DNA lesion by reactive oxygen species (ROS). To identify and characterize OGG1 gene (TJ-OGG1) in the copepod Tigriopus japonicus, the full-length cDNA sequence, genomic structure, and promoter region was analyzed. In addition, to investigate transcriptional change of TJ-OGG1 mRNA under oxidative stress conditions, T. japonicus were exposed to environmental oxidative inducers, H(2)O(2), UV-B, and heavy metals (Cd, Cu, and Zn), respectively. The full-length cDNA of TJ-OGG1 gene was 1708 bp in length, encoding 343 amino acid residues. The deduced amino acid sequences of TJ-OGG1 showed a 56% similarity with human. Two conserved motifs (HhH and PVD loop) and two conserved residues (lysine and aspartic acid) in active sites were also observed. TJ-OGG1 genome structure contained six exons and five introns and putative transcription factor binding sites such as Nrf-2, p53, ERE-half sites, and XRE were detected on the promoter region. TJ-OGG1 mRNA level was increased at approximately three-fold (P<0.05) at 1mM and approximately 4-fold (P<0.01) at 10mM of H(2)O(2), respectively. UV-B enhanced the expression of TJ-OGG1 mRNA at 15kJ/m(2) (P<0.05) and more (P<0.001). In a time-course experiment, TJ-OGG1 gene was highly transcribed within 12h after exposure of 10 kJ/m(2) (P<0.01) and 20 kJ/m(2) (P<0.001). The expression of TJ-OGG1 mRNA after exposure to Cu and Cd for 96 h was significantly up-regulated at 0.1 μg/L and then remarkably reduced in a dose-dependent manner. Their transcript levels did not change at low dose (0.1 and 1 μg/L) but were dose-dependently down-regulated at high dose (10 and 100 μg/L). These findings suggest that H(2)O(2), UV-B, and heavy metals induce oxidative stress and generate oxidatively damaged DNA. Consequently, the enhanced TJ-OGG1 gene expression would be associated with active involvement of TJ-OGG1 gene in DNA repair process as a cellular protection mechanism. This is the first report on the cloning and characterization of OGG1 gene in aquatic animals. This study is helpful for a better understanding of the molecular mechanisms of cellular protection against various environmental oxidative stress inducers such as UV-B and heavy metals in aquatic invertebrates.
authors: Department of Chemistry, College of Natural Sciences, Hanyang University, Seoul 133-791, South Korea.
authors: Bo-Mi
authors: BM
authors: Kim
authors: Jae-Sung
authors: JS
authors: Rhee
authors: Jung Soo
authors: JS
authors: Seo
authors: Il-Chan
authors: IC
authors: Kim
authors: Young-Mi
authors: YM
authors: Lee
authors: Jae-Seong
authors: JS
authors: Lee
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002104:Cadmium / Q000494:pharmacology; D003001:Cloning, Molecular; D033342:Copepoda / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D003300:Copper / Q000494:pharmacology; D045647:DNA Glycosylases / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000528:radiation effects; D006147:Guanine / Q000031:analogs & derivatives / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008969:Molecular Sequence Data; D016877:Oxidants / Q000494:pharmacology; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D018076:DNA, Complementary; D016877:Oxidants; D014157:Transcription Factors; D002104:Cadmium; C024829:8-hydroxyguanine; D006147:Guanine; D003300:Copper; D006861:Hydrogen Peroxide; D045647:DNA Glycosylases