06.22.06
Maternal vs. Paternal Imprinting: A Brief Review
The July edition of Nature Reviews Genetics contains a brief article summarizing recent research into the question, “Do mothers and fathers imprint differently?”
- Two imprinting mechanisms have been described to date: one involves an imprinting control region (ICR) at the well-studied H19/Igf2 locus. On the maternal chromosome the ICR acts as an insulator to inhibit expression of Igf2, whereas DNA methylation of the ICR on the paternal allele spreads to and silences the H19 gene. The other mechanism involves an ICR that acts as a promoter for a paternally expressed non-coding RNA, first described at the Igf2r locus by Denise Barlow and colleagues. Kcnq1ot1 is the second example of a non-coding RNA with a direct role in the silencing of imprinted genes. The fact that the activity of the ICR in the first mechanism occurs on the maternal chromosome whereas in the second, described by Tilghman and colleagues, the activity applies to the paternal chromosome raises the possibility that the two mechanisms are gender-specific. Understanding how other clusters of imprinted genes are silenced should verify this interesting possibility.
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