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

• Published in: The Journal of biological chemistry Vol. 270; no. 27; p. 16402
• Main Authors: Deepak K. Srivastava, Teresa Y. Rawson, Stephen D. Showalter, Samuel H. Wilson
• Format: Journal Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology 07.07.1995
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.27.16402

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 O 6 -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.