Overexpression of a Rrp1 transgene reduces the somatic mutation and recombination frequency induced by oxidative DNA damage in Drosophila melanogaster.

Abstract

Recombination repair protein 1 (Rrpl) includes a C-terminal region homologous to several DNA repair proteins, including Escherichia coli exonuclease III and human APE, that repair oxidative and alkylation damage to DNA. The nuclease activities of Rrpl include apurinic/apyrimidinic endonuclease, 3'-phosphodiesterase, 3'-phosphatase, and 3'-exonuclease. As shown previously, the C-terminal nuclease region of Rrpl is sufficient to repair oxidative-and alkylationinduced DNA damage in repair-deficient E. coli mutants. DNA strand-transfer and single-stranded DNA renaturation activities are associated with the unique N-terminal region of Rrpl, which suggests possible additional functions that include recombinational repair or homologous recombination. By using the Drosophila w/w+ mosaic eye system, which detects loss of heterozygosity as changes in eye pigmentation, somatic mutation and recombination frequencies were determined in transgenic flies overexpressing wild-type Rrpl protein from a heat-shock-inducible transgene. A large decrease in mosaic clone frequency is observed when Rrpl overexpression precedes treatment with y-rays, bleomycin, or paraquat. In contrast, Rrpl overexpression does not alter the spot frequency after treatment with the alkylating agents methyl methanesulfonate or methyl nitrosourea. A reduction in mosaic clone frequency depends on the expression of the Rrpl transgene and on the nature of the induced DNA damage. These data suggest a lesion-specific involvement ofRrpl in the repair of oxidative DNA damage.DNA repair enzymes are ubiquitous in all organisms studied and display a large range of functional specificities, including both exquisitely specialized and very broad selectivities (1-4). These enzymes allow cells and organisms to preserve genomic integrity, to prevent the accumulation of deleterious mutations, and, in some cases, to survive lethal challenges.A major class of DNA damage is caused by reactive oxygen species that lead to altered DNA bases and to both singlestranded DNA (ssDNA) and double-stranded DNA breaks (5, 6). Oxidative damage is thought to be mutagenic, clastogenic, and carcinogenic and may contribute to the aging process. The general pathway known as base excision repair plays a major role in repair of oxidative DNA damage. One crucial enzyme involved in this pathway is the class II apurinic/apyrimidinic (AP) endonuclease, of which two major families are known, the exonuclease III family and the endonuclease IV family. Mutants of either Escherichia coli exonuclease III or endonuclease IV (or its yeast homologue APN1) are sensitive to oxidative and alkylation DNA damage and show increased spontaneous mutation rates (7,8).Drosophila Rrpl is a well-characterized AP endonuclease that is enzymatically similar to E. coli exonuclease III (9). Its nucleolytic functions, encoded by the C-terminal third of Rrpl,The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with ...

Acute exercise stress promotes Ref1/Nrf2 signalling and increases mitochondrial antioxidant activity in skeletal muscle

“…), and overexpression of Ref1 protein in Drosophila protected cells from genotoxic oxidative stress (Szakmary et al . ), whereas downmodulation of Ref1 caused hypersensitivity to oxidative damage (Walker et al . ).…”

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The Drosophila Splicing Factor PSI Is Phosphorylated by Casein Kinase II and Tousled-Like Kinase

“…Using GST pulldowns, we showed that Rrp1 requires the presence of Ser 42 to be able to interact efficiently with PSI. Rrp1 is an exonuclease that is involved in DNA damage repair [31]. Connections between splicing and DNA repair have been previously recognized [32].…”

Mutation in the Drosophila melanogaster adenosine receptor gene selectively decreases the mosaic hyperplastic epithelial outgrowth rates in wts or dco heterozygous flies

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