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The redox/DNA repair protein, Ref-1, is essential for early embryonic development in mice
S Xanthoudakis1, R J Smeyne, J D Wallace
1Department of Central Nervous System Research, Hoffmann-La Roche Inc., Nutley, NJ 07110, USA.
Abstract:
The DNA-binding activity of AP-1 proteins is modulated, in vitro, by a posttranslational mechanism involving reduction oxidation. This mode of regulation has been proposed to control both the transcriptional activity and the oncogenic potential of Fos and Jun. Previous studies revealed that reduction of oxidized Fos and Jun by a cellular protein, Ref-1, stimulates sequence-specific AP-1 DNA-binding activity. Ref-1, a bifunctional protein, is also capable of initiating the repair of apurinic/apyrymidinic sites in damaged DNA. The relationship between the redox and DNA repair activities of Ref-1 is intriguing; both activities have been suggested to play an important role in the cellular response to oxidative stress. To investigate the physiological function of Ref-1, we used a gene targeting strategy to generate mice lacking a functional ref-1 gene. We report here that heterozygous mutant mice develop into adulthood without any apparent abnormalities. In contrast, homozygous mutant mice, lacking a functional ref-1 gene, die during embryonic development. Detailed analysis indicates that death occurs following blastocyst formation, shortly after the time of implantation. Degeneration of the mutant embryos is clearly evident at embryonic day 5.5. These findings demonstrate that Ref-1 is essential for early embryonic development.
Insights
Mice lacking the Ref-1 gene die during early embryonic development. This demonstrates that Ref-1 is essential for early development and cellular response to oxidative stress.
Area of Science:
- Molecular Biology
- Genetics
- Developmental Biology
Background:
- AP-1 protein activity is regulated by redox mechanisms, influencing transcriptional activity and oncogenic potential.
- Ref-1 (redox factor-1) is a bifunctional protein involved in reducing oxidized Fos and Jun, thereby stimulating AP-1 DNA-binding activity.
- Ref-1 also possesses DNA repair capabilities, specifically initiating the repair of apurinic/apyrymidinic sites, and is implicated in cellular response to oxidative stress.
Purpose of the Study:
- To investigate the physiological function of Ref-1 in vivo.
- To determine the essentiality of Ref-1 for embryonic development using a gene targeting strategy.
Main Methods:
- Gene targeting was employed to generate mice lacking a functional ref-1 gene.
- Heterozygous and homozygous mutant mice were analyzed for developmental abnormalities.
- Embryonic development was monitored and analyzed at specific time points, including embryonic day 5.5.
Main Results:
- Heterozygous mutant mice lacking one functional ref-1 gene developed into adulthood without apparent abnormalities.
- Homozygous mutant mice lacking a functional ref-1 gene exhibited embryonic lethality, dying post-blastocyst formation and shortly after implantation.
- Degeneration of homozygous mutant embryos was observed by embryonic day 5.5.
Conclusions:
- Ref-1 is essential for early embryonic development in mice.
- The absence of Ref-1 leads to developmental failure during the critical post-implantation period.
- These findings highlight the crucial role of Ref-1 in developmental processes beyond its known roles in DNA binding and repair.