Role of Piwi proteins in mammalian transposon silencing

In a recent Nature publication, Reuter et al. report on the study of certain small RNAs that affect the fertility of male mice. Piwi-interacting RNAs (piRNAs) act together with Piwi proteins Mili (also known as Piwil2) and Miwi (also known as Piwil4) in a genome defense mechanism that initiates transposon silencing via DNA methylation in the mouse male embryonic germ line. This silencing depends on the participation of the Piwi proteins in a slicer-dependent piRNA amplification pathway and is essential for male fertility.

The researchers cite the use of Epicentre’s Ribo-Zero™ Kit (Human/Mouse/Rat) to remove interfering ribosomal RNA from the experimental matrix, allowing closer study of the interactions between piRNAs. They also used the ScriptSeq™ mRNA-Seq Kit for an unusual application: sequencing small RNAs. Under normal circumstances, small RNAs <50-60 nucleotides are better suited for Epicentre's ScriptMiner™ Small RNA-Seq Kit, due to potential issues with the ScriptSeq method at the 5’ end of small RNAs. These results demonstrate that the ScriptSeq Kit has the ability to prepare RNA-Seq libraries from RNA types other than mRNA, including small RNAs.

Reuter, M. et al. (2011). Miwi catalysis is required for piRNA amplification-independent LINE1 transposon silencing Nature, 480 (7376), 264-267 DOI: 10.1038/nature10672