scholarly journals Endogenous Retroviruses Walk a Fine Line between Priming and Silencing

Viruses ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 792 ◽  
Author(s):  
Harrison Cullen ◽  
Andrea J. Schorn
Keyword(s):  
Small Rna ◽  
Binding Sites ◽  
Small Rnas ◽  
Genome Stability ◽  
Sequence Variation ◽  
Endogenous Retroviruses ◽  
Highly Active ◽  
Trna Primer ◽  
Ltr Retroelements ◽  
Transcription And Replication

Endogenous retroviruses (ERVs) in mammals are closely related to infectious retroviruses and utilize host tRNAs as a primer for reverse transcription and replication, a hallmark of long terminal repeat (LTR) retroelements. Their dependency on tRNA makes these elements vulnerable to targeting by small RNAs derived from the 3′-end of mature tRNAs (3′-tRFs), which are highly expressed during epigenetic reprogramming and potentially protect many tissues in eukaryotes. Here, we review some key functions of ERV reprogramming during mouse and human development and discuss how small RNA-mediated silencing maintains genome stability when ERVs are temporarily released from heterochromatin repression. In particular, we take a closer look at the tRNA primer binding sites (PBS) of two highly active ERV families in mice and their sequence variation that is shaped by the conflict of successful tRNA priming for replication versus evasion of silencing by 3′-tRFs.

scholarly journals Location specific annealing of miR-122 and other small RNAs defines an Hepatitis C Virus 5′ UTR regulatory element with distinct impacts on virus translation and genome stability

2020 ◽  
Vol 48 (16) ◽  
pp. 9235-9249 ◽  
Author(s):  
Rasika D Kunden ◽  
Sarah Ghezelbash ◽  
Juveriya Q Khan ◽  
Joyce A Wilson
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Virus Replication ◽  
Small Rna ◽  
Small Rnas ◽  
Rna Structure ◽  
Genome Stability ◽  
Regulatory Element ◽  
Entry Site ◽  
Genome Stabilization

Abstract Hepatitis C virus (HCV) replication requires annealing of a liver specific small-RNA, miR-122 to 2 sites on 5′ untranslated region (UTR). Annealing has been reported to (a) stabilize the genome, (b) stimulate translation and (c) promote the formation of translationally active Internal Ribosome Entry Site (IRES) RNA structure. In this report, we map the RNA element to which small RNA annealing promotes HCV to nucleotides 1–44 and identify the relative impact of small RNA annealing on virus translation promotion and genome stabilization. We mapped the optimal region on the HCV genome to which small RNA annealing promotes virus replication to nucleotides 19–37 and found the efficiency of viral RNA accumulation decreased as annealing moved away from this region. Then, by using a panel of small RNAs that promote replication with varying efficiencies we link the efficiency of lifecycle promotion with translation stimulation. By contrast small RNA annealing stabilized the viral genome even if they did not promote virus replication. Thus, we propose that miR-122 annealing promotes HCV replication by annealing to an RNA element that activates the HCV IRES and stimulates translation, and that miR-122 induced HCV genome stabilization is insufficient alone but enhances virus replication.

scholarly journals Small RNA Plays Important Roles in Virus–Host Interactions

Viruses ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1271
Author(s):  
Hui Dai ◽  
Weifeng Gu
Keyword(s):  
Influenza Virus ◽  
Small Rna ◽  
Small Rnas ◽  
Viral Transcription ◽  
Host Interactions ◽  
Recent Advances ◽  
Transcription And Replication

Non-coding small RNAs play important roles in virus–host interactions. For hosts, small RNAs can serve as sensors in antiviral pathways including RNAi and CRISPR; for viruses, small RNAs can be involved in viral transcription and replication. This paper covers several recent discoveries on small RNA mediated virus–host interactions, and focuses on influenza virus cap-snatching and a few important virus sensors including PIR-1, RIG-I like protein DRH-1 and piRNAs. The paper also discusses recent advances in mammalian antiviral RNAi.

scholarly journals The Diversity of Plant Small RNAs Silencing Mechanisms

2019 ◽  
Vol 73 (5) ◽  
pp. 362-367 ◽  
Author(s):  
Jens A. Schröder ◽  
Pauline E. Jullien
Keyword(s):  
Gene Regulation ◽  
Gene Silencing ◽  
Small Rna ◽  
Small Rnas ◽  
Genome Stability ◽  
Molecular Mechanisms ◽  
Transcriptional Gene Silencing ◽  
Regulation Mechanism ◽  
Regulatory Processes ◽  
Post Transcriptional Gene Silencing

Small RNAs gene regulation was first discovered about 20 years ago. It represents a conserve gene regulation mechanism across eukaryotes and is associated to key regulatory processes. In plants, small RNAs tightly regulate development, but also maintain genome stability and protect the plant against pathogens. Small RNA gene regulation in plants can be divided in two canonical pathways: Post-transcriptional Gene Silencing (PTGS) that results in transcript degradation and/or translational inhibition or Transcriptional Gene Silencing (TGS) that results in DNA methylation. In this review, we will focus on the model plant Arabidopsis thaliana. We will provide a brief overview of the molecular mechanisms involved in canonical small RNA pathways as well as introducing more atypical pathways recently discovered.

scholarly journals Mechanism of Stochastic Resonance in a Quorum Sensing Network Regulated by Small RNAs

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ya-nan Zhu ◽  
Jianwei Shen ◽  
Yong Xu
Keyword(s):  
Quorum Sensing ◽  
Stochastic Resonance ◽  
Small Rna ◽  
Small Rnas ◽  
Cell Communication ◽  
The Other ◽  
Important Process ◽  
Positive Role ◽  
Bacterial Quorum Sensing ◽  
Bacterial Quorum

Bacterial quorum sensing (QS) is an important process of cell communication and more and more attention is paid to it. Moreover, the noises are ubiquitous in nature and often play positive role. In this paper, we investigate how the noise enhances the QS though the stochastic resonance (SR) and explain the mechanism of SR in this quorum sensing network. In addition, we also discuss the interaction between the small RNA and the other genes in this network and discover the biological importance.

scholarly journals Intertissue small RNA communication mediates the acquisition and inheritance of hormesis in Caenorhabditis elegans

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Emiko Okabe ◽  
Masaharu Uno ◽  
Saya Kishimoto ◽  
Eisuke Nishida
Keyword(s):  
Caenorhabditis Elegans ◽  
Small Rna ◽  
Stress Resistance ◽  
Environmental Conditions ◽  
Production System ◽  
Small Rnas ◽  
Communication Systems ◽  
Rna Transport ◽  
Phenotypic Changes ◽  
Induced Stress

AbstractEnvironmental conditions can cause phenotypic changes, part of which can be inherited by subsequent generations via soma-to-germline communication. However, the signaling molecules or pathways that mediate intertissue communication remain unclear. Here, we show that intertissue small RNA communication systems play a key role in the acquisition and inheritance of hormesis effects – stress-induced stress resistance – in Caenorhabditis elegans. The miRNA-processing enzyme DRSH-1 is involved in both the acquisition and the inheritance of hormesis, whereas worm-specific Argonaute (WAGO) proteins, which function with endo-siRNAs, are involved only in its inheritance. Further analyses demonstrate that the miRNA production system in the neuron and the small RNA transport machinery in the intestine are both essential for its acquisition and that both the transport of small RNAs in the germline and the germline Argonaute HRDE-1 complex are required for its inheritance. Our results thus demonstrate that overlapping and distinct roles of small RNA systems in the acquisition and inheritance of hormesis effects.

scholarly journals The Importance of the Small RNA Chaperone Hfq for Growth of Epidemic Yersinia pestis, but Not Yersinia pseudotuberculosis, with Implications for Plague Biology

2010 ◽  
Vol 192 (16) ◽  
pp. 4239-4245 ◽  
Author(s):  
Guangchun Bai ◽  
Andrey Golubov ◽  
Eric A. Smith ◽  
Kathleen A. McDonough
Keyword(s):  
Yersinia Pestis ◽  
Small Rna ◽  
Small Rnas ◽  
Yersinia Pseudotuberculosis ◽  
Etiologic Agent ◽  
Growth Restriction ◽  
Rna Chaperone ◽  
Unique Biology ◽  
Severe Growth

ABSTRACT Yersinia pestis, the etiologic agent of plague, has only recently evolved from Yersinia pseudotuberculosis. hfq deletion caused severe growth restriction at 37°C in Y. pestis but not in Y. pseudotuberculosis. Strains from all epidemic plague biovars were similarly affected, implicating Hfq, and likely small RNAs (sRNAs), in the unique biology of the plague bacillus.

scholarly journals Intergenerational metabolic priming by sperm piRNAs

2021 ◽  
Author(s):  
Adelheid Lempradl ◽  
Unn Kugelberg ◽  
Mary Iconomou ◽  
Ian Beddows ◽  
Daniel Nätt ◽  
...  
Keyword(s):  
Small Rna ◽  
Small Rnas ◽  
Target Gene ◽  
Epigenetic Inheritance ◽  
Mature Sperm ◽  
Transcriptional Reprogramming ◽  
Complementary Sequences ◽  
Specific Manner ◽  
Dietary Sugar ◽  
Pirna Pathway

Preconception parental environment can reproducibly program offspring phenotype without altering the DNA sequence, yet the mechanisms underpinning this epigenetic inheritance remains elusive. Here, we demonstrate the existence of an intact piRNA-pathway in mature Drosophila sperm and show that pathway modulation alters offspring gene transcription in a sequence-specific manner. We map a dynamic small RNA content in developing sperm and find that the mature sperm carry a highly distinct small RNA cargo. By biochemical pulldown, we identify a small RNA subset bound directly to piwi protein. And, we show that piRNA-pathway controlled sperm small RNAs are linked to target gene repression in offspring. Critically, we find that full piRNA-pathway dosage is necessary for the intergenerational metabolic and transcriptional reprogramming events triggered by high paternal dietary sugar. These data provide a direct link between regulation of endogenous mature sperm small RNAs and transcriptional programming of complementary sequences in offspring. Thus, we identify a novel mediator of paternal intergenerational epigenetic inheritance.

scholarly journals The Caenorhabditis elegans TDRD5/7-like protein, LOTR-1, interacts with the helicase ZNFX-1 to balance epigenetic signals in the germline

2021 ◽  
Author(s):  
Elisabeth A Marnik ◽  
Miguel Vasconcelos Almeida ◽  
P Giselle Cipriani ◽  
George Chung ◽  
Edoardo Caspani ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Small Rna ◽  
Small Rnas ◽  
Brood Size ◽  
Homologous Proteins ◽  
P Granules ◽  
Transposon Silencing ◽  
Tudor Domain ◽  
Germ Granules

LOTUS and Tudor domain containing proteins have critical roles in the germline. Proteins that contain these domains, such as Tejas/Tapas in Drosophila, help localize Vasa to the germ granules and facilitate piRNA-mediated transposon silencing. The homologous proteins in mammals, TDRD5 and TDRD7, are required during spermiogenesis. Until now, proteins containing both LOTUS and Tudor domains in Caenorhabditis elegans have remained elusive. Here we describe LOTR-1 (D1081.7), which derives its name from its LOTUS and Tudor domains. Interestingly, LOTR-1 docks next to P granules to colocalize with the broadly conserved Z-granule helicase, ZNFX-1. LOTR-1's Z-granule association requires its Tudor domain, but both LOTUS and Tudor deletions affect brood size when coupled with a knockdown of the Vasa homolog glh-1. In addition to interacting with the germ-granule components WAGO-1, PRG-1 and DEPS-1, we identified a Tudor-dependent association with ZNFX-1. Like znfx-1 mutants, lotr-1 mutants lose small RNAs from the 3' ends of WAGO and Mutator targets, reminiscent of the loss of piRNAs from the 3' ends of piRNA precursor transcripts in mouse Tdrd5 mutants. Our work suggests that LOTR-1 acts in a conserved mechanism that brings small RNA generating mechanisms towards the 3' ends of small RNA templates or precursors.

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