Differential methylation of a CpG-island concatemer in hemi- and homozygous transgenic mice.
Methylation-free islands (MFIs), clusters of non-methylated CpG-dinucleotides in mammalian genomes, are associated with a majority of studied genes. By which precise mechanism they maintain their unmethylated status is unknown. The behaviour of transgenic MFIs may contribute to unveil this enigma. We have generated a high-copy number transgenic line with the MFI from the murine Thy-1.1 allele. A stable, minor fraction of this otherwise non-methylated DNA became completely methylated in all adult tissues tested. Furthermore, individuals homozygous for the transgene showed a significantly higher proportion of methylated copies compared to the hemizygous state. These findings support the hypothesis that a limited pool of trans-acting factors are involved in maintaining the hypomethylated state.
Biotechnology Centre, University of Oslo, Norway.
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Gundersen
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Kolstø
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Prydz
D000818:Animals; D000954:Antigens, Surface / Q000235:genetics; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification; D015226:Dinucleoside Phosphates / Q000032:analysis* / Q000378:metabolism; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008745:Methylation; D051379:Mice; D008822:Mice, Transgenic; D015183:Restriction Mapping; D018800:Thy-1 Antigens
D000954:Antigens, Surface; D004247:DNA; D015226:Dinucleoside Phosphates; D018800:Thy-1 Antigens; C015772:CpG dinucleotide