Retrotransposon Silencing by piRNAs: Ping-Pong Players Mark Their Sub-Cellular Boundaries

Retrotransposon Silencing by piRNAs: Ping-Pong Players Mark Their Sub-Cellular Boundaries

Germ cells of many animals exhibit characteristic cytoplasmic structures— termed germ granules or nuage—which are ribonucleoprotein (RNP) amorphous aggregates without limiting membranes and are often closely associated with nuclei or mitochondria [1]. In several model animals, such as Drosophila, Caenorhabditis elegans, and Xenopus, studies on germ granules have mainly focused on their asymmetr...

SnapShot: Mouse piRNAs, PIWI Proteins, and the Ping-Pong Cycle

SnapShot: Fly piRNAs, PIWI Proteins, and the Ping-Pong Cycle

Transposon Silencing by piRNAs

In animal cells, small RNA molecules, called piRNAs, defend the genome against selfish DNA elements such as transposons. In this issue, Klattenhoff et al. (2009) report that an HP1 family protein, Rhino, is required for piRNA generation and transposon silencing in Drosophila germline cells. The results provide a link between heterochromatin and piRNA-mediated genome defense.

Arbovirus-Derived piRNAs Exhibit a Ping-Pong Signature in Mosquito Cells

The siRNA pathway is an essential antiviral mechanism in insects. Whether other RNA interference pathways are involved in antiviral defense remains unclear. Here, we report in cells derived from the two main vectors for arboviruses, Aedes albopictus and Aedes aegypti, the production of viral small RNAs that exhibit the hallmarks of ping-pong derived piwi-associated RNAs (piRNAs) after infection...