Trans-dominant inhibition of poly(ADP-ribosyl)ation potentiates alkylation-induced shuttle-vector mutagenesis in Chinese hamster cells.
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 gamma-radiation. Likewise, carcinogen-induced gene amplification, viewed as a manifestation of genomic instability, was potentiated by the overexpression of the PARP DNA-binding domain. 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.
Tatsumi-Miyajima
J
J
Institute of Radiation Genetics, Faculty of Medicine, Kyoto University, Japan.
Küpper
J H
JH
Takebe
H
H
Bürkle
A
A
D000477:Alkylating Agents / Q000494:pharmacology; D000478:Alkylation; D000818:Animals; D016466:CHO Cells; D002461:Cell Line, Transformed; D006224:Cricetinae; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008770:Methylnitrosourea / Q000494:pharmacology; D016254:Mutagenesis, Insertional; D000067856:Poly(ADP-ribose) Polymerase Inhibitors
D000477:Alkylating Agents; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D008770:Methylnitrosourea; D003907:Dexamethasone