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Caterina Catalanotto, Carlo Cogoni, Giuseppe Zardo
The finding that small non-coding RNAs (ncRNAs) are able to control gene expression in a sequence specific manner has had a massive impact on biology. Recent improvements in high throughput sequencing and computational prediction methods have allowed the discovery and classification of several types of ncRNAs. Based on their precursor structures, biogenesis pathways and modes of action, ncRNAs are classified as small interfering RNAs (siRNAs), microRNAs (miRNAs), PIWI-interacting RNAs (piRNAs), endogenous small interfering RNAs (endo-siRNAs or esiRNAs), promoter associate RNAs (pRNAs), small nucleolar RNAs (snoRNAs) and sno-derived RNAs...
October 13, 2016: International Journal of Molecular Sciences
M J Madison-Villar, Cheng Sun, Nelson C Lau, Matthew L Settles, Rachel Lockridge Mueller
Most of the largest vertebrate genomes are found in salamanders, a clade of amphibians that includes 686 species. Salamander genomes range in size from 14 to 120 Gb, reflecting the accumulation of large numbers of transposable element (TE) sequences from all three TE classes. Although DNA loss rates are slow in salamanders relative to other vertebrates, high levels of TE insertion are also likely required to explain such high TE loads. Across the Tree of Life, novel TE insertions are suppressed by several pathways involving small RNA molecules...
October 14, 2016: Journal of Molecular Evolution
Takamasa Hirano, Hidetoshi Hasuwa, Haruhiko Siomi
The mouse testis has served as a popular model system to study a wide range of biological processes, including germ cell development, meiosis, epigenetic changes of chromatin, transposon silencing, and small RNA-mediated epigenetic modifications. PIWI-interacting RNAs (piRNAs) are a class of small RNAs that are almost exclusively expressed in animal gonads. They repress transposons by forming effector complexes with PIWI proteins to maintain genome integrity of the germline. Here we describe detailed procedures of how to produce monoclonal antibodies against a mouse nuclear PIWI protein, MIWI2, which functions in de novo DNA methylation of target transposon loci...
2017: Methods in Molecular Biology
Nathalie Boissot, Alexandra Schoeny, Flavie Vanlerberghe-Masutti
We review half a century of research on Cucumis melo resistance to Aphis gossypii from molecular to field levels. The Vat gene is unique in conferring resistance to both A. gossypii and the viruses it transmits. This double phenotype is aphid clone-dependent and has been observed in 25 melon accessions, mostly from Asia. It is controlled by a cluster of genes including CC-NLR, which has been characterized in detail. Copy-number polymorphisms (for the whole gene and for a domain that stands out in the LLR region) and single-nucleotide polymorphisms have been identified in the Vat cluster...
2016: Frontiers in Plant Science
Yibei Xiao, Ailong Ke
piRNA guides the action of PIWI proteins to silence deleterious transposons in animal reproductive tissues. Biogenesis of piRNA-induced silencing complex (piRISC) involves a multi-step process. In this issue, Matsumoto et al. report the first crystal structure of a PIWI-clade protein displaying a guide RNA, ready for action.
October 6, 2016: Cell
Yong Liu
RNA molecules that are unable to translate into proteins are classified as non-coding RNA. Non-coding RNA (ncRNA) genes include highly abundant and functionally important RNAs such as transfer RNAs, microRNAs (miRNAs), siRNAs, snRNAs, exRNAs and piRNAs. The number of ncRNAs encoded within the human genome is unknown; however, recent transcriptomic and bioinformatic studies suggest the existence of thousands of ncRNAs. Furthermore, small ncRNAs, including miRNAs and PIWI-interacting RNAs (piRNAs), play an imperative role in the regulation of gene expression of numerous biological and pathological processes...
October 2016: Oncology Letters
Naoki Matsumoto, Hiroshi Nishimasu, Kazuhiro Sakakibara, Kazumichi M Nishida, Takamasa Hirano, Ryuichiro Ishitani, Haruhiko Siomi, Mikiko C Siomi, Osamu Nureki
PIWI-clade Argonaute proteins associate with PIWI-interacting RNAs (piRNAs) and silence transposable elements in animal gonads. Here, we report the crystal structure of a silkworm PIWI-clade Argonaute, Siwi, bound to the endogenous piRNA, at 2.4 Å resolution. Siwi adopts a bilobed architecture consisting of N-PAZ and MID-PIWI lobes, in which the 5' and 3' ends of the bound piRNA are anchored by the MID-PIWI and PAZ domains, respectively. A structural comparison of Siwi with AGO-clade Argonautes reveals notable differences in their nucleic-acid-binding channels, likely reflecting the distinct lengths of their guide RNAs and their mechanistic differences in guide RNA loading and cleavage product release...
October 6, 2016: Cell
Chun-Lei Wang, Zhi-Peng Wang, Jia-Qi Wang, Ming-You Li, Xiao-Wu Chen
Piwi-interacting RNA (piRNA) plays an important role in the gonadal development and maintenance of Teleostei. In this study, piRNA libraries derived from the adult gonads of Japanese flounder (Paralichthys olivaceus) were generated using next-generation sequencing technology. Using zebrafish piRNAs as a reference, 5 865 unique candidate piRNAs were identified; 289 candidate piRNA clusters (PRCs) were generated from the above piRNAs. Among the isolated candidate PRCs, a total of 38 ovary-specific, 45 ovary-bias, 24 testis-specific, and 131 testis-bias PRCs were found...
September 18, 2016: Dong Wu Xue Yan Jiu, Zoological Research
Peiwen Liu, Yunqiao Dong, Jinbao Gu, Santhosh Puthiyakunnon, Yang Wu, Xiao-Guang Chen
BACKGROUND: In eukaryotic organisms, Piwi-interacting RNAs (piRNAs) control the activities of mobile genetic elements and ensure genome maintenance. Recent evidence indicates that piRNAs are involved in multiple biological pathways, including transcriptional regulation of protein-coding genes, sex determination and even interactions between host and pathogens. Aedes albopictus is a major invasive species that transmits a number of viral diseases in humans. Ae. albopictus has the largest genome and the highest abundance of repetitive sequences when compared with members that belong to Culicidae with a published genome...
September 29, 2016: Parasites & Vectors
E Y Yakushev, E A Mikhaleva, Y A Abramov, O A Sokolova, I M Zyrianova, V A Gvozdev, M S Klenov
The Piwi protein and its orthologs are considered as the key components of the piRNA machinery implicated in transcriptional silencing of transposons. Неre, we show that nuclear localization of the Piwi protein is required not only for transposon repression, but also for proper differentiation of germline stem cells (GSCs). piwi^(Nt) mutation that causes loss of nuclear Piwi and its retention in the cytoplasm leads to the accumulation of undifferentiated GSC-like cells. The analysis of piwi^(Nt) mutation in combination with a bam gene mutation blocking GSC differentiation shows that the loss of nuclear Piwi decreases GSC proliferation rate...
July 2016: Molekuliarnaia Biologiia
John Huntriss, Jianping Lu, Karen Hemmings, Rosemary Bayne, Richard Anderson, Anthony Rutherford, Adam Balen, Kay Elder, Helen M Picton
PURPOSE: Gametocyte-specific factor 1 has been shown in other species to be required for the silencing of retrotransposons via the Piwi-interacting RNA (piRNA) pathway. In this study, we aimed to isolate and assess expression of transcripts of the gametocyte-specific factor 1 (GTSF1) gene in the human female germline and in preimplantation embryos. METHODS: Complementary DNA (cDNA) libraries from human fetal ovaries and testes, human oocytes and preimplantation embryos and ovarian follicles isolated from an adult ovarian cortex biopsy were used to as templates for PCR, cloning and sequencing, and real time PCR experiments of GTSF1 expression...
September 19, 2016: Journal of Assisted Reproduction and Genetics
Daniel Rodríguez-Leal, Amanda Castillo-Cobián, Isaac Rodríguez-Arévalo, Jean-Philippe Vielle-Calzada
Small RNA (sRNA)-mediated gene silencing represents a conserved regulatory mechanism controlling a wide diversity of developmental processes through interactions of sRNAs with proteins of the ARGONAUTE (AGO) family. On the basis of a large phylogenetic analysis that includes 206 AGO genes belonging to 23 plant species, AGO genes group into four clades corresponding to the phylogenetic distribution proposed for the ten family members of Arabidopsis thaliana. A primary analysis of the corresponding protein sequences resulted in 50 sequences of amino acids (blocks) conserved across their linear length...
2016: Frontiers in Plant Science
Preethi Krishnan, Sunita Ghosh, Bo Wang, Mieke Heyns, Kathryn Graham, John R Mackey, Olga Kovalchuk, Sambasivarao Damaraju
One of the most abundant, yet least explored, classes of RNA is the small nucleolar RNAs (snoRNAs), which are well known for their involvement in post-transcriptional modifications of other RNAs. Although snoRNAs were only considered to perform housekeeping functions for a long time, recent studies have highlighted their importance as regulators of gene expression and as diagnostic/prognostic markers. However, the prognostic potential of these RNAs has not been interrogated for breast cancer (BC). The objective of the current study was to identify snoRNAs as prognostic markers for BC...
2016: PloS One
Kanako Kojima-Kita, Satomi Kuramochi-Miyagawa, Ippei Nagamori, Narumi Ogonuki, Atsuo Ogura, Hidetoshi Hasuwa, Takashi Akazawa, Norimitsu Inoue, Toru Nakano
During the development of mammalian embryonic germ cells, global demethylation and de novo DNA methylation take place. In mouse embryonic germ cells, two PIWI family proteins, MILI and MIWI2, are essential for the de novo DNA methylation of retrotransposons, presumably through PIWI-interacting RNAs (piRNAs). Although piRNA-associated MIWI2 has been reported to play critical roles in the process, its molecular mechanisms have remained unclear. To identify the mechanism, transgenic mice were produced; they contained a fusion protein of MIWI2 and a zinc finger (ZF) that recognized the promoter region of a type A LINE-1 gene...
September 13, 2016: Cell Reports
Jonathon D Klein, Chunxu Qu, Xiaoyang Yang, Yiping Fan, Chunlao Tang, Jamy C Peng
Drosophila melanogaster Piwi functions within the germline stem cells (GSCs) and the somatic niche to regulate GSC self-renewal and differentiation. How Piwi influences GSCs is largely unknown. We uncovered a genetic interaction between Piwi and c-Fos in the somatic niche that influences GSCs. c-Fos is a proto-oncogene that influences many cell and developmental processes. In wild-type ovarian cells, c-Fos is post-transcriptionally repressed by Piwi, which destabilized the c-Fos mRNA by promoting the processing of its 3' untranslated region (UTR) into Piwi-interacting RNAs (piRNAs)...
September 2016: PLoS Genetics
Fu Yang, Rongwen Xi
Transposable elements or transposons are DNA pieces that can move around within the genome and are, therefore, potential threat to genome stability and faithful transmission of the genetic information in the germline. Accordingly, self-defense mechanisms have evolved in the metazoan germline to silence transposons, and the primary mechanism requires the germline-specific non-coding small RNAs, named Piwi-interacting RNA (piRNAs), which are in complex with Argonaute family of PIWI proteins (the piRNA-RISC complexes), to silence transposons...
September 6, 2016: Cellular and Molecular Life Sciences: CMLS
Hua Luo, Xiao Li, Julie M Claycomb, Howard D Lipshitz
Metazoan embryos undergo a maternal-to-zygotic transition (MZT) during which maternal gene products are eliminated and the zygotic genome becomes transcriptionally active. During this process RNA-binding proteins (RBPs) and the microRNA-induced silencing complex (miRISC) target maternal mRNAs for degradation. In Drosophila, the Smaug (SMG), Brain tumor (BRAT) and Pumilio (PUM) RBPs bind to and direct the degradation of largely distinct subsets of maternal mRNAs. SMG has also been shown to be required for zygotic synthesis of mRNAs and several members of the miR-309 family of microRNAs (miRNAs) during the MZT...
September 2, 2016: G3: Genes—Genomes—Genetics
Hiroki Sakai, Megumi Sumitani, Yasuhiko Chikami, Kensuke Yahata, Keiro Uchino, Takashi Kiuchi, Susumu Katsuma, Fugaku Aoki, Hideki Sezutsu, Masataka G Suzuki
In Bombyx mori (B. mori), Fem piRNA originates from the W chromosome and is responsible for femaleness. The Fem piRNA-PIWI complex targets and cleaves mRNAs transcribed from the Masc gene. Masc encodes a novel CCCH type zinc-finger protein and is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. In the present study, several silkworm strains carrying a transgene, which encodes a Fem piRNA-resistant Masc mRNA (Masc-R), were generated. Forced expression of the Masc-R transgene caused female-specific lethality during the larval stages...
August 2016: PLoS Genetics
Weikang Zhang, Hongliang Liu, Jieyun Yin, Wenting Wu, Dakai Zhu, Christopher I Amos, Shenying Fang, Jeffrey E Lee, Yi Li, Jiali Han, Qingyi Wei
The Piwi-piRNA pathway is important for germ cell maintenance, genome integrity, DNA methylation and retrotransposon control and thus may be involved in cancer development. In this study, we comprehensively analyzed prognostic roles of 3,116 common SNPs in PIWI-piRNA pathway genes in melanoma disease-specific survival. A published genome-wide association study (GWAS) by The University of Texas M.D. Anderson Cancer Center was used to identify associated SNPs, which were later validated by another GWAS from the Harvard Nurses' Health Study and Health Professionals Follow-up Study...
December 15, 2016: International Journal of Cancer. Journal International du Cancer
Dingfang Li, Longqiang Luo, Wen Zhang, Feng Liu, Fei Luo
BACKGROUND: Predicting piwi-interacting RNA (piRNA) is an important topic in the small non-coding RNAs, which provides clues for understanding the generation mechanism of gamete. To the best of our knowledge, several machine learning approaches have been proposed for the piRNA prediction, but there is still room for improvements. RESULTS: In this paper, we develop a genetic algorithm-based weighted ensemble method for predicting transposon-derived piRNAs. We construct datasets for three species: Human, Mouse and Drosophila...
2016: BMC Bioinformatics
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