‘Naked genome’ during epigenetic reprogramming protected by newly identified small-RNA
Cold Spring Harbor Laboratory | July 11, 2017

Our genomes are minefields, studded with potentially damaging DNA sequences over which hundreds of thousands of sentries stand guard. These sentries, called epigenetic marks, attach to the double helix at such spots and prevent the underlying DNA sequences from springing into destructive action.

About half the human genome is composed of these damaging sequences. They are places where ancient viruses and parasitic elements called transposons and retrotransposons have incorporated themselves over the long course of evolution. It’s astonishing, then, to consider that during two of the most crucial processes in the life cycle, the sentries are removed, leaving the genome naked. The defenders are quickly welcomed back, but only after an interval in which the epigenetic slate is wiped clean.

Today in Cell, a team from Cold Spring Harbor Laboratory (CSHL) describes its discovery of what might be considered emergency replacements for the sentries, shock troops pressed into service across the genome only during these curiously undefended moments. Specifically, these defenders are protecting the genome in mammalian embryos, at the very early point in their development before they are implanted in the wall of the maternal uterus.

The preimplantation embryo is one of two normal settings in which  are wiped clean before being reinscribed. The other setting is a step in the formation of germline cells – sperm and eggs—which have temporary defenders already known to biology, so-called piwi-interacting RNAs (piRNAs). The research published today, led by first author Andrea Schorn, a postdoctoral investigator in the lab of Rob Martienssen, demonstrates that another species of small RNA performs an analogous genome-defending role in preimplantation embryos during an interval of epigenetic reprogramming.

The ELP aggregated and excerpted this blog/article to reflect the diversity of news, opinion, and analysis. Read full, original post: Newly identified small RNA fragments defend the genome when it’s ‘naked’

Want to stay up to date on the latest epigenetics news? Follow ELP on Twitter and like the Facebook