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DNA methylation at mammalian replication origins
T Rein1, T Kobayashi, M Malott
1NICHD, National Institutes of Health, Bethesda, Maryland 20892-2753, USA.
The Journal of Biological Chemistry
|August 28, 1999
Summary
DNA methylation does not universally control mammalian replication origins. However, at specific sites like origin beta, DNA methylation is crucial for regulating replication initiation.
Area of Science:
- Molecular Biology
- Genetics
- Epigenetics
Background:
- DNA methylation regulates DNA replication origins in E. coli.
- Mammalian replication origins may be associated with methylated CpG dinucleotides.
- The role of DNA methylation in mammalian DNA replication is not fully understood.
Purpose of the Study:
- To investigate the role of DNA methylation in mammalian DNA replication origins.
- To determine if DNA methylation is a universal feature of mammalian replication origins.
- To examine the impact of DNA methylation on the activity of specific replication origins.
Main Methods:
- Bisulfite sequencing was used to detect 5-methylcytosines at specific DNA sequences.
- Remethylation rates and hypomethylation effects were studied at origin beta (ori-beta).
- The activity of ori-beta was assessed in hypomethylated hamster cells.
Main Results:
- The region upstream of the human c-myc gene, a potential replication origin, was found to be unmethylated.
- DNA methylation does not play a significant role in prereplication complex reassembly in mammalian cells.
- Hypomethylation of ori-beta led to a loss of its selective activation, indicating a role for DNA methylation in origin selection.
Conclusions:
- DNA methylation is not a universal regulator of mammalian replication origins.
- While not universally required, DNA methylation can determine replication initiation site selection at specific loci.
- The findings challenge the notion of DNA methylation as a universal component of mammalian replication origins but highlight its locus-specific regulatory role.