title: DNA damage response of cloned DNA beta-polymerase promoter is blocked in mutant cell lines deficient in protein kinase A.
abstract: DNA beta-polymerase (beta-pol), one of the recognized DNA polymerizing enzymes in vertebrates, has a role in 'very short patch' gap-filling synthesis during nucleotide excision DNA repair. In human and mouse, the enzyme is encoded by a single-copy gene located on the short arm of chromosome 8 near the centromere. In a series of studies, we have found that the cloned human beta-pol promoter is regulated by signals acting through the single ATF/CRE palindrome in the core promoter. These signals include transactivation by: adenovirus E1a/E1b proteins; activated p21ras; and in CHO cells, treatment with the DNA damaging agent MNNG. Hence, several types of stimulatory signals are mediated through the single ATF/CRE site, including DNA damage induction. To understand the mechanism of beta-pol promoter activation by MNNG in CHO cells, we asked whether induction of the cAMP/protein kinase A pathway can increase transcription of the cloned promoter in this system. Agents that increase cellular cAMP levels (8-BrcAMP; forskolin and IBMx) activated the beta-pol promoter fusion gene in transient expression experiments, and a mutation in the ATF/CRE palindrome blocked this response. Thus, the ATF/CRE site appears to be cAMP responsive in the CHO cell system. We found that the activation of the cloned beta-pol promoter by MNNG does not occur with two mutant CHO cell lines that are deficient in protein kinase A activity. Further, simultaneous treatment of wild-type CHO cells, with MNNG and to elevate cAMP, failed to result in an additive effect for activation of the beta-pol promoter. Thus, these effectors may act through a common pathway. These results suggest that the activation of the cloned beta-pol promoter in CHO cells following MNNG treatment is mediated through the cAMP/protein kinase A signal transduction pathway.
authors.affiliation: Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: E W
authors.initials: EW
authors.lastname: Englander
authors.forename: S H
authors.initials: SH
authors.lastname: Wilson
mesh_terms: D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D004247:DNA; D004249:DNA Damage; D004256:DNA Polymerase I / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000172:deficiency / Q000235:genetics*; D015398:Signal Transduction; D014162:Transfection
chemical_list: D008769:Methylnitronitrosoguanidine; D004247:DNA; D011494:Protein Kinases; D004256:DNA Polymerase I