Piwi RNAs articles from across Nature Portfolio

piRNA processing factors and piRNA/PIWI complex are found in intermitochondrial cement (IMC) and chromatoid body (CB). Here, the authors show that piRNA loading orchestrates MIWI translocation from the IMC to CB, demonstrating its crucial role in spermatogenesis.

In Caenorhabditis tropicalis, selective expression of genetic alleles from one parent but not the other can arise from maternally inherited small transcripts acting via the PIWI-interacting RNA host defence pathway.

To control transposable elements, fruit flies rely on distinct genomic regions called piRNA clusters. Here, new piRNA clusters were identified across diverse Drosophila species, displaying a conserved and specialised role in the control of endogenous retroviruses in ovarian somatic cells.

The role of PIWI proteins in mammalian reproduction remains poorly understood. Here, using golden hamsters, the authors establish expression profiles for all four PIWIs during gametogenesis and characterize their associated reproductive defects.

Bombyx Vasa assembles Vasa bodies, the site of transposon silencing by Siwi and Ago3-piRISC formation. Here, the authors show Vasa sequesters transposon mRNAs in Vasa bodies via phase separation requiring RNA binding and self-association of Vasa.

Pachytene Piwi-interacting RNAs (piRNAs) expressed in mammalian germ lines are abundant, but their evolution and function are not fully understood. Here, the authors find that pachytene piRNA loci are hotspots of structural variation, which underlies rapid piRNA birth, divergence, and loss.

Mice deficient in the piRNA pathway display sterility only in males. Taking advantage of a more representative piRNA pathway in golden hamsters, three studies now demonstrate that the piRNA pathway is essential for fertility in hamsters of both sexes and thus strongly link this small RNA pathway to fertility regulation in both men and women.

Wu and Zamore discuss models of piRNA function and suggest experimental criteria to be followed in order to validate them.

The nuclear piRNA pathway safeguards genome integrity in the germline by silencing transposable elements. Three recent studies have identified new players in the mammalian pathway. Two of these, TEX15 and SPOCD1, might provide a link between piRNA-guided complexes that recognize genomic targets and the molecular machinery that induces DNA methylation and transcriptional repression during mouse spermatogenesis.

This paper identifies a non-retroviral endogenous viral element in mosquitoes that has antiviral functions.

Piwi proteins are aberrantly induced in human tumours, but their function in cancer has been poorly understood. A study now shows that in the absence of piRNA loading, human PIWIL1 promotes pancreatic cancer metastasis by acting as a co-activator of the anaphase-promoting complex/cyclosome (APC/C) to degrade the cell-adhesion protein Pinin.