A piece of the pi(e): The diverse roles of animal piRNAs and their PIWI partners

Lim, Robyn Su May; Kai, Toshie

doi:10.1016/j.semcdb.2015.10.025

Cited by 39 publications

(38 citation statements)

References 301 publications

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“…Most of these factors were shown to be essential in piRNA amplification and transposon silencing. 2,3,51 The perinuclear granules positive for Vasa2 found throughout the development of Nematostella (Fig. 5) are highly reminiscent of nuage.…”

Section: Discussionmentioning

confidence: 94%

“…This finding is in line with the conserved role of piRNAs in transposon surveillance in numerous animals of different phyla. [2][3][4] Notably, in Nematostella the fraction of piRNAs targeting protein-coding genes (41%) is significantly larger compared with investigated samples of humans and Drosophila (18.4% and 3.2%, respectively, shown in Fig. 7B), possibly implying a role of piRNAs in the regulation of gene expression in Nematostella.…”

Section: Nematostella Pirnas Target Tes and Protein-coding Genesmentioning

confidence: 87%

“…3,9,10 In Hydra, the two PIWI proteins are expressed in multipotent i-cells and germline stem cells, but also in mitotic epithelial cells with stem cell character in the ectoderm and endoderm. 15,16 vasa expression is as well detected in i-cells and epithelial cells in addition to the gonads.…”

Section: Discussionmentioning

confidence: 99%

“…With growing size of the oocytes the signal fades, recapitulating the artifact of impeding yolk content or signal dilution encountered by in situ hybridization. piRNA pathway proteins and associated piRNAs are commonly maternally inherited in other animals 3 and consistently, mass spectrometry analysis identified PIWI and Vasa proteins in mature Nematostella eggs. 29,30 It seems that nuage is transiently dissolved during mitosis, as we detected elongated DAPI-positive M-phase chromosomes without surrounding Vasa2 staining ( Fig.…”

Section: Nematostella Vasa2 Protein Is Expressed In Granules Around Nmentioning

confidence: 92%

“…piRNAs are transcribed as long, single-stranded precursors from piRNA clusters, genomic loci enriched with truncated transposon sequences, or active transposons. 2,3 Precursor transcripts are processed into primary piRNAs with a U at position 1 in distinct cytoplasmic perinuclear foci collectively called nuage ("cloud" in French), due to their appearance in TEM images. 4,5 There, secondary piRNAs complementary in 10 nucleotides with primary piRNA and a corresponding A at position 10 are generated via the ping pong cycle, a mechanism combining transposon destruction and amplification of piRNAs.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of the piRNA pathway during development of the sea anemone Nematostella vectensis

et al. 2017

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PIWI-interacting RNAs (piRNAs) and associated proteins comprise a conserved pathway for silencing transposons in metazoan germlines. piRNA pathway components are also expressed in multipotent somatic stem cells in various organisms. piRNA functions have been extensively explored in bilaterian model systems, however, comprehensive studies in non-bilaterian phyla remain limited. Here we investigate the piRNA pathway during the development of Nematostella vectensis, a well-established model system belonging to Cnidaria, the sister group to Bilateria. To date, no population of somatic stem cells has been identified in this organism, despite its long life-span and regenerative capacities that require a constant cell-renewal. We show that Nematostella piRNA pathway components are broadly expressed in early developmental stages, while piRNAs themselves show differential expression, suggesting specific developmental roles of distinct piRNA families. In adults, piRNA associated proteins are enriched in the germline but also expressed in somatic cells, indicating putative stem cell properties. Furthermore, we provide experimental evidence that Nematostella piRNAs cleave transposable elements as well as protein-coding genes. Our results demonstrate that somatic expression of piRNA associated proteins as well as the roles of piRNAs in transposon repression and gene regulation are likely ancestral features that evolved before the split between Cnidaria and Bilateria.

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Section: Discussionmentioning

confidence: 94%

Section: Nematostella Pirnas Target Tes and Protein-coding Genesmentioning

confidence: 87%