Phorbol Ester Abrogates Up-regulation of DNA Polymerase β by DNA-alkylating Agents in Chinese Hamster Ovary Cells

Mammalian DNA polymerase β (β-pol), a DNA repair polymerase, is known to be constitutively expressed in cultured cells, but treatment of cells with the DNA-alkylating agents MNNG or methyl methanesulfonate has been shown to up-regulate β-pol mRNA level. To further characterize this response, we prep...

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Bibliographic Details
Published in:The Journal of biological chemistry 1995-07, Vol.270 (27), p.16402-16408
Main Authors: Srivastava, Deepak K., Rawson, Teresa Y., Showalter, Stephen D., Wilson, Samuel H.
Format: Article
Language:English
Subjects:
Alkylating Agents - pharmacology
Amino Acid Sequence
Animals
Antibodies, Monoclonal
CHO Cells
Cricetinae
DNA Damage
DNA Polymerase I - biosynthesis
DNA Polymerase I - genetics
DNA Polymerase I - immunology
DNA Repair
Drug Antagonism
Epitope Mapping
Immunoblotting
Methyl Methanesulfonate - pharmacology
Methylnitronitrosoguanidine - pharmacology
Molecular Sequence Data
Rats
Signal Transduction
Tetradecanoylphorbol Acetate - pharmacology
Up-Regulation - drug effects
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Summary:Mammalian DNA polymerase β (β-pol), a DNA repair polymerase, is known to be constitutively expressed in cultured cells, but treatment of cells with the DNA-alkylating agents MNNG or methyl methanesulfonate has been shown to up-regulate β-pol mRNA level. To further characterize this response, we prepared a panel of monoclonal antibodies and used one of them to quantify β-pol in whole cell extracts by immunoblotting. We found that treatment of Chinese hamster ovary cells with either DNA-alkylating agent up-regulated the β-pol protein level 5-10-fold. This induction appeared to be secondary to DNA alkylation, as induction was not observed with a genetically altered cell line overexpressing the DNA repair enzyme O6-methylguanine-methyltransferase. We also found that 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment of wild type Chinese hamster ovary cells increased expression of β-pol protein (~10-fold). Any interrelationship between this TPA response and the DNA-alkylation response was studied by treatment with combinations of MNNG and TPA. The β-pol up-regulation observed with MNNG treatment was abrogated by TPA, and conversely the up-regulation observed with TPA treatment was abrogated by MNNG.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.270.27.16402