Trans-dominant inhibition of poly(ADP-ribosyl)ation potentiates alkylation-induced shuttle-vector mutagenesis in Chinese hamster cells |
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Authors: | Tatsumi-Miyajima Junko Küpper Jan-Heiner Takebe Hiraku Bürkle Alexander |
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Institution: | (1) Institute of Radiation Genetics, Faculty of Medicine, Kyoto University, Kyoto, Japan;(2) Abteilung Tumorvirologie, Deutsches Krebsforschungszentrum, Heidelberg, Germany |
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Abstract: | In most eukaryotic cells, the catalytic activation of poly(ADP-ribose) polymerase (PARP) represents one of the earliest cellular responses to the infliction of DNA damage. To study the biological function(s) of poly(ADP-ribosyl)ation, we have established stable transfectants (COM3 cells) of the SV40-transformed Chinese hamster cell line C060 which conditionally overexpress the PARP DNA-binding domain upon addition of dexamethasone. We could demonstrate that DNA-binding domain overexpression, which leads to trans-dominant inhibition of poly(ADP-ribosyl)ation, potentiates the cytotoxicity of alkylation treatment and of -radiation 21]. Likewise, carcinogen-induced gene amplification, viewed as a manifestation of genomic instability, was potentiated by the overexpression of the PARP DNA-binding domain 22]. Recently, we studied the effect of trans-dominant PARP inhibition on mutagenesis by employing a shuttle-vector assay in which mutagen-exposed plasmid pYZ289 is electroporated into COM3 cells. We could show that dexamethasone-induced overexpression of the PARP DNA-binding domain in COM3 cells potentiates the mutagenicity of the alkylating agent N-methyl-N-nitrosourea, while no effect of dexamethasone treatment on mutation frequency was recorded in control cells lacking the PARP DNA-binding domain transgene. Taken together, our results further substantiate the role of poly(ADP-ribosyl)ation in the maintenance of genomic integrity and stability under conditions of genotoxic stress. |
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Keywords: | poly(ADP-ribose) polymerase mutagenesis genomic instability alkylating agents shuttle vector |
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