Functions of PIWI Proteins in Gene Regulation: New Arrows Added to the piRNA Quiver

Piwi-interacting RNAs (piRNAs) and PIWI proteins play key functions in a wide range of biological and developmental processes through the regulation of cellular mRNAs, in addition to their role in transposable element (TE) repression. Evolutionary studies indicate that these PIWI functions in mRNA regulatory programs, occurring in both germ and somatic cells, are ancestral. Recent advances have widely expanded our understanding of these functions of PIWI proteins, identifying new mechanisms of action and strengthening their importance through their conservation in distant species. In this review, we discuss the latest findings regarding piRNA/PIWI-dependent mRNA decay in germ cells and during the maternal-to-zygotic transition in embryos combined with new modes of action of PIWI proteins in mRNA stabilization and translational activation and piRNA-independent roles of PIWI proteins in cancer.

Automated summary

piRNAs and PIWI proteins play crucial roles in biological and developmental processes by regulating cellular mRNAs. These functions are ancestral and recent research has expanded our understanding of the mechanisms of action and the conservation of PIWI proteins in distant species.