Formation and persistence of O6-ethylguanine in genomic and transgene DNA in liver and brain of λlacZ transgenic mice treated with N-ethyl-N-nitrosourea
| Autor: | Mientjes, E.J., Hochleitner, K., Luiten-Schuite, A., Delft, J.H.M. van, Thomale, J., Berends, F., Rajewsky, M.F., Lohman, P.H.M., Baan, R.A. |
|---|---|
| Přispěvatelé: | TNO Voeding |
| Jazyk: | angličtina |
| Rok vydání: | 1996 |
| Předmět: |
DNA Repair
polymerase chain reaction animal experiment mutagen testing Mice Transgenic dna Toxicology Sensitivity and Specificity animal tissue lactose operon ethylnitrosourea Mice Animals controlled study guanine animal genetics 7 ethylguanine enzyme inhibition mouse 6 ethylguanine 7-ethylguanine nonhuman Genome 6-ethylguanine Mutagenicity Tests mutagenic agent transgene drug effect article mutagenicity Brain 6 o alkylguanine dna alkyltransferase Bacteriophage lambda transgenic mouse guanine derivative female priority journal Lac Operon Liver dna adduct drug derivative physiology biosynthesis metabolism immunoblotting Mutagens |
| Zdroj: | Carcinogenesis, 11, 17, 2449-2454 |
| Popis: | LacZ transgenic mice are suitable for short-term mutagenicity studies in vivo. Mutagenicity in these mice is determined in the lacZ transgene. Since the lacZ gene is of bacterial origin the question has been raised whether DNA-adduct formation and repair in the transgene are comparable to those in total genomic DNA. Mice were treated with N-ethyl-N-nitrosourea (ENU) and killed at several time points following treatment. Some mice were pretreated with O6-benzylguanine to inactivate the repair protein O6-alkylguanine-DNA alkyltransferase (AGT). O6-ethylguanine (O6-EtG) was determined in lacZ in liver and brain by means of a monoclonal antibody-based immunoaffinity assay. In addition, O6-EtG and N7-ethylguanine (N7-EtG) were assayed in total genomic DNA of liver and brain with an immunoslotblot procedure. In liver, the initial O6-EtG level in total genomic DNA was 1.6 times that in lacZ. The extent of repair of O6-EtG during the first 1.5 h after treatment was 2.1 times that in lacZ. At later time points, O6-EtG repair was the same. N7-EtG repair in genomic DNA was evident. In contrast to the liver, little repair of O6-EtG in total genomic and lacZ DNA occurred in the brain while N7-EtG was repaired. No initial difference in O6-EtG levels were found in lacZ and genomic brain DNA. These findings indicate that in the liver, total genomic DNA is more accessible than lacZ to ENU and/or the AGT protein, during the first 1.5 h following treatment. Because the difference in O6-EtG levels in the transgene and genomic DNA in the liver is restricted to the first 1.5 h after treatment, while the fixation of mutations occurs at later time points, O6-EtG-induced mutagenesis most likely is also very similar in both types of DNA. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|