PIWI-interacting RNAs: small RNAs with big functions

@article{Ozata2018PIWIinteractingRS,
  title={PIWI-interacting RNAs: small RNAs with big functions},
  author={Deniz M. Ozata and Ildar V Gainetdinov and Ansgar Zoch and D{\'o}nal O’Carroll and Phillip D. Zamore},
  journal={Nature Reviews Genetics},
  year={2018},
  volume={20},
  pages={89-108}
}
In animals, PIWI-interacting RNAs (piRNAs) of 21–35 nucleotides in length silence transposable elements, regulate gene expression and fight viral infection. piRNAs guide PIWI proteins to cleave target RNA, promote heterochromatin assembly and methylate DNA. The architecture of the piRNA pathway allows it both to provide adaptive, sequence-based immunity to rapidly evolving viruses and transposons and to regulate conserved host genes. piRNAs silence transposons in the germ line of most animals… 

Comparative analysis of piRNA sequences, targets and functions in nematodes

This work characterized the piRNA pathway in C. briggsae and identified a set of protein-coding genes that are evolutionarily conserved piRNA targets, and found that transcripts with few introns are prone to small RNA overamplification.

An introduction to PIWI-interacting RNAs (piRNAs) in the context of metazoan small RNA silencing pathways

This review aims to introduce principles of piRNA silencing in the context of metazoan small RNA pathways and identify novel nucleases, helicases and RNA binding proteins identified in piRNA biology.

Emerging roles and functional mechanisms of PIWI-interacting RNAs.

The most recent advances in the understanding of piRNA biogenesis, the molecular mechanisms of pi RNA function and the emerging roles of piRNAs in germ line development mainly in flies and mice, and in infertility, cancer and neurological diseases in humans are discussed.

Conserved Small Nucleotidic Elements at the Origin of Concerted piRNA Biogenesis from Genes and lncRNAs

A new type of a conserved regulatory pathway is brought to light, the snetDNA-pathway, by which short sequences can include independent genes and lncRNAs in the same biological pathway, suggesting that such regulation networks are recurrent, possibly conserved, in evolutionary history.

A pathway to produce non-coding piRNAs from endogenous protein-coding regions supports Drosophila spermatogenesis

The data highlight that Drosophila testes employ a unique strategy to expand the diversity of germline piRNAs supporting late spermatogenesis, and provide evidence that Ago2-bound short interfering (si)RNAs and micro(mi) RNAs specify precursors and direct endo-piRNA biogenesis.

Structural basis for piRNA targeting.

Cryo-electron microscopy structures of a PIWI-piRNA complex from the sponge Ephydatia fluviatilis with and without target RNAs are presented, and a biochemical analysis of target recognition is presented, making piRNAs less promiscuous than miRNAs.

Primate piRNA Cluster Evolution Suggests Limited Relevance of Pseudogenes in piRNA-Mediated Gene Regulation

It is shown that pseudogenes in reserve orientation relative to piRNA cluster transcription direction generally do not exhibit signs of selection pressure and cause weakly conserved targeting of homologous genes among species, suggesting a lack of functional constraints and thus only a minor significance for gene regulation in most cases.

GTSF1 accelerates target RNA cleavage by PIWI-clade Argonaute proteins

GTSF1 potentiates the weak, intrinsic, piRNA-directed RNA cleavage activities of PIWI proteins, transforming them into efficient endoribonucleases, and is thus an example of an auxiliary protein that potentiate the catalytic activity of an Argonaute protein.

Genetic polymorphisms lead to major, locus-specific, variation in piRNA production in mouse

The sequencing and analysis of small RNAs from the mouse male germline of four classical inbred strains, one inbred wild-derived strain and one outbred strain are reported, finding that genetic differences between individuals underlie variation in piRNA expression.
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