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Treatment of mice with 5-azacytidine efficiently activates silent retroviral genomes in different tissues
Abstract:
The drug 5-azacytidine was injected into mice to activate silent retroviral genomes. The Mov-7 and Mov-10 substrains of mice were used, each of which carries a Moloney murine leukemia provirus with mutations in the coding regions at nonidentical positions. These proviral genomes are highly methylated and are not expressed in the animal. A single injection of the drug into postnatal mice induced transcription of the endogenous defective proviral genomes in thymus, spleen, and liver at 3 days after treatment. No viral transcription was detected in the brain of drug-exposed animals. When postnatal Mov-7/Mov-10 F1 mice were treated with the drug, infectious virus was generated efficiently and resulted in virus spread and viremia in all animals by 3 weeks of age. In contrast, infectious virus was not generated in F1 mice that had been treated during gestation with up to sublethal doses of the drug. Our results demonstrate that injection of 5-azacytidine can be used to efficiently and reproducibly activate silent genes in different cell populations of postnatal mice.
Insights
The drug 5-azacytidine activates silent retroviral genomes in postnatal mice, leading to efficient infectious virus generation. Prenatal drug exposure prevented this activation, highlighting the critical timing for gene activation.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Murine leukemia proviruses are often silenced through methylation.
- Activating these silent proviruses can provide insights into gene regulation and viral reactivation.
Purpose of the Study:
- To investigate the efficacy of 5-azacytidine in activating silent retroviral genomes in mice.
- To determine the impact of drug administration timing on retroviral activation and infectious virus generation.
Main Methods:
- Injection of 5-azacytidine into postnatal Mov-7 and Mov-10 substrain mice.
- Analysis of viral transcription in thymus, spleen, liver, and brain tissues.
- Assessment of infectious virus generation, spread, and viremia in treated F1 mice.
Main Results:
- 5-azacytidine induced transcription of defective proviral genomes in postnatal mice.
- Infectious virus was efficiently generated and spread in postnatal but not gestationally treated F1 mice.
- No viral transcription was observed in the brain following drug treatment.
Conclusions:
- 5-azacytidine is an effective agent for activating silent genes in various postnatal mouse tissues.
- The timing of 5-azacytidine administration is crucial for efficient retroviral reactivation and infectious virus production.