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Programming the transcriptional state of replicating methylated dna
W Stunkel1, S Ait-Si-Ali, P L Jones
1NICHD, National Institutes of Health, Bethesda, Maryland 20814, USA. stunkelw@mail.nih.gov
The Journal of Biological Chemistry
|March 30, 2001
Summary
DNA replication creates a window for transcription factors to influence gene activity. However, binding of these factors does not automatically lead to passive demethylation of DNA at the replication fork.
Area of Science:
- Epigenetics
- Molecular Biology
- Genetics
Background:
- CpG methylation is crucial for maintaining DNA sequence information during cell division.
- DNA methyltransferase enzymes are responsible for this methylation process at the replication fork.
- Transcription factors may interact with DNA at replication forks, potentially influencing methylation patterns.
Purpose of the Study:
- To investigate whether transcription factors binding at replication forks can prevent DNA remethylation.
- To determine if DNA replication provides a window for regulatory factors to modulate gene activity.
- To explore the relationship between transcription factor binding, gene activation, and DNA demethylation.
Main Methods:
- Injection of a linearized, methylated, and partially single-stranded reporter plasmid into Xenopus oocytes.
- Monitoring transcriptional activity following DNA replication.
- Assessing DNA methylation status in promoter regions near transcription factor binding sites.
Main Results:
- DNA replication, in conjunction with Gal4-VP16 and DNA methyltransferase activity, creates a temporal window for gene regulation.
- Regulatory factors can activate or repress gene activity during this window.
- Despite transcription factor binding and gene activation, demethylation in the promoter region of newly synthesized DNA did not occur.
Conclusions:
- The presence of DNA binding transcriptional activators alone is insufficient to drive "passive" demethylation at the replication fork.
- Gene regulation at the replication fork is a complex process involving DNA methyltransferase, replication-coupled chromatin assembly, and regulatory factors.