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.
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 epigenetic marks 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’