scholarly journals Functional dissection of the ARGONAUTE7 promoter

2018 ◽  
Author(s):  
J. Steen Hoyer ◽  
Jose L. Pruneda-Paz ◽  
Ghislain Breton ◽  
Mariah A. Hassert ◽  
Emily E. Holcomb ◽  
...  
Keyword(s):  
Binding Sites ◽  
Rna Silencing ◽  
Leaf Shape ◽  
Effector Proteins ◽  
Transcriptional Gene Silencing ◽  
Antiviral Defense ◽  
Post Transcriptional Gene Silencing ◽  
And Function ◽  
Central Effector ◽  
Ranked List

AbstractARGONAUTES are the central effector proteins of RNA silencing which bind target transcripts in a small RNA-guided manner. Arabidopsis thaliana has ten ARGONAUTE (AGO) genes, with specialized roles in RNA-directed DNA methylation, post-transcriptional gene silencing, and antiviral defense. To better understand specialization among AGO genes at the level of transcriptional regulation we tested a library of 1497 transcription factors for binding to the promoters of AGO1, AGO10, and AGO7 using yeast 1-hybrid assays. A ranked list of candidate DNA-binding TFs revealed binding of the AGO7 promoter by a number of proteins in two families: the miR156-regulated SPL family and the miR319-regulated TCP family, both of which have roles in developmental timing and leaf morphology. Possible functions for SPL and TCP binding are unclear: we showed that these binding sites are not required for the polar expression pattern of AGO7, nor for the function of AGO7 in leaf shape. Normal AGO7 transcription levels and function appear to depend instead on an adjacent 124-bp region. Progress in understanding the structure of this promoter may aid efforts to understand how the conserved AGO7-triggered TAS3 pathway functions in timing and polarity.

scholarly journals Trigger and suppression of antiviral defenses by grapevine Pinot gris virus (GPGV): novel insights into virus-host interaction

2021 ◽  
Author(s):  
Giulia Tarquini ◽  
Laura Pagliari ◽  
Paolo Ermacora ◽  
Rita Musetti ◽  
Giuseppe Firrao
Keyword(s):  
Rna Silencing ◽  
Infectious Clone ◽  
Transcriptional Gene Silencing ◽  
Antiviral Defense ◽  
Small Interfering Rnas ◽  
Host Interaction ◽  
Post Transcriptional Gene Silencing ◽  
Gene Expression Analyses ◽  
Grapevine Pinot Gris Virus

Grapevine Pinot gris virus (GPGV) is an emerging trichovirus that has been putatively associated with a novel grapevine disease known as grapevine leaf mottling and deformation (GLMD). Yet the role of GPGV in GLMD disease is poorly understood since it has been detected both in symptomatic and symptomless grapevines. We exploited a recently constructed GPGV infectious clone (pRI::GPGV-vir) to induce an antiviral response in Nicotiana benthamiana plants. In silico prediction of virus-derived small interfering RNAs (vsiRNAs) and gene expression analyses revealed the involvement of DCL4, AGO5 and RDR6 genes during GPGV infection, suggesting the activation of the post-transcriptional gene-silencing (PTGS) pathway as a plant antiviral defense. PTGS suppression assays in transgenic N. benthamiana 16c plants revealed the ability of the GPGV coat protein to suppress RNA silencing. This work provides novel insights on the interaction between GPGV and its host, revealing the ability of the virus to trigger and suppress antiviral RNA silencing.

scholarly journals FIERY1 promotes microRNA accumulation by suppressing rRNA-derived small interfering RNAs in Arabidopsis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Chenjiang You ◽  
Wenrong He ◽  
Runlai Hang ◽  
Cuiju Zhang ◽  
Xiaofeng Cao ◽  
...  
Keyword(s):  
Rna Degradation ◽  
Transcriptional Gene Silencing ◽  
Rrna Processing ◽  
Small Interfering Rnas ◽  
Post Transcriptional Gene Silencing ◽  
Processing Defects ◽  
And Function ◽  
Mirna Abundance ◽  
Unknown Link

Abstract Plant microRNAs (miRNAs) associate with ARGONAUTE1 (AGO1) to direct post-transcriptional gene silencing and regulate numerous biological processes. Although AGO1 predominantly binds miRNAs in vivo, it also associates with endogenous small interfering RNAs (siRNAs). It is unclear whether the miRNA/siRNA balance affects miRNA activities. Here we report that FIERY1 (FRY1), which is involved in 5′−3′ RNA degradation, regulates miRNA abundance and function by suppressing the biogenesis of ribosomal RNA-derived siRNAs (risiRNAs). In mutants of FRY1 and the nuclear 5′−3′ exonuclease genes XRN2 and XRN3, we find that a large number of 21-nt risiRNAs are generated through an endogenous siRNA biogenesis pathway. The production of risiRNAs correlates with pre-rRNA processing defects in these mutants. We also show that these risiRNAs are loaded into AGO1, causing reduced loading of miRNAs. This study reveals a previously unknown link between rRNA processing and miRNA accumulation.

scholarly journals Virus and Viroid-Derived Small RNAs as Modulators of Host Gene Expression: Molecular Insights Into Pathogenesis

2021 ◽  
Vol 11 ◽  
Author(s):  
S. V. Ramesh ◽  
Sneha Yogindran ◽  
Prabu Gnanasekaran ◽  
Supriya Chakraborty ◽  
Stephan Winter ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Small Rnas ◽  
Rna Silencing ◽  
Transcriptional Gene Silencing ◽  
Genomic Rnas ◽  
Post Transcriptional Gene Silencing ◽  
Viroid Infection ◽  
Wide Range ◽  
Associated Symptoms ◽  
Sequence Complementarity

Virus-derived siRNAs (vsiRNAs) generated by the host RNA silencing mechanism are effectors of plant’s defense response and act by targeting the viral RNA and DNA in post-transcriptional gene silencing (PTGS) and transcriptional gene silencing (TGS) pathways, respectively. Contrarily, viral suppressors of RNA silencing (VSRs) compromise the host RNA silencing pathways and also cause disease-associated symptoms. In this backdrop, reports describing the modulation of plant gene(s) expression by vsiRNAs via sequence complementarity between viral small RNAs (sRNAs) and host mRNAs have emerged. In some cases, silencing of host mRNAs by vsiRNAs has been implicated to cause characteristic symptoms of the viral diseases. Similarly, viroid infection results in generation of sRNAs, originating from viroid genomic RNAs, that potentially target host mRNAs causing typical disease-associated symptoms. Pathogen-derived sRNAs have been demonstrated to have the propensity to target wide range of genes including host defense-related genes, genes involved in flowering and reproductive pathways. Recent evidence indicates that vsiRNAs inhibit host RNA silencing to promote viral infection by acting as decoy sRNAs. Nevertheless, it remains unclear if the silencing of host transcripts by viral genome-derived sRNAs are inadvertent effects due to fortuitous pairing between vsiRNA and host mRNA or the result of genuine counter-defense strategy employed by viruses to enhance its survival inside the plant cell. In this review, we analyze the instances of such cross reaction between pathogen-derived vsiRNAs and host mRNAs and discuss the molecular insights regarding the process of pathogenesis.

scholarly journals Phytobacterial Type III Effectors HopX1, HopAB1 and HopF2 Enhance Sense-Post-Transcriptional Gene Silencing Independently of Plant R Gene-Effector Recognition

2011 ◽  
Vol 24 (8) ◽  
pp. 907-917 ◽  
Author(s):  
Panagiotis F. Sarris ◽  
Shang Gao ◽  
Konstantinos Karademiris ◽  
Hailing Jin ◽  
Kriton Kalantidis ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Pathogenic Bacteria ◽  
Fluorescent Protein ◽  
Effector Proteins ◽  
Transcriptional Gene Silencing ◽  
Type Iii ◽  
Post Transcriptional Gene Silencing ◽  
Rna Pathways ◽  
Green Fluorescent ◽  
Effector Recognition

Plant- and animal-pathogenic bacteria deploy a variable arsenal of type III effector proteins (T3EP) to manipulate host defense. Specific biochemical functions and molecular or subcellular targets have been demonstrated or proposed for a growing number of T3EP but remain unknown for the majority of them. Here, we show that transient expression of genes coding certain bacterial T3EP (HopAB1, HopX1, and HopF2), which did not elicit hypersensitive response (HR) in transgenic green fluorescent protein (GFP) Nicotiana benthamiana 16C line, enhanced the sense post-transcriptional gene silencing (S-PTGS) triggered by agrodelivery of a GFP-expressing cassette and the silencing enhancement could be blocked by two well-known viral silencing suppressors. Further analysis using genetic truncations and site-directed mutations showed that the receptor recognition domains of HopAB1 and HopX1 are not involved in enhancing silencing. Our studies provide new evidence that phytobacterial pathogen T3EP manipulate the plant small interfering RNA pathways by enhancing silencing efficiency in the absence of effector-triggered immunity signaling and suggest that phytopathogenic bacterial effectors affect host RNA silencing in yet other ways than previously described.

scholarly journals Short interfering RNAs are Associated with Virus Resistance in a Woody Perennial Fruit Tree (Prunus domestica)

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 862D-862
Author(s):  
Jean-Michel Hily ◽  
Ralph Scorza* ◽  
Michel Ravelonandro
Keyword(s):  
Virus Resistance ◽  
Rna Silencing ◽  
Transcriptional Gene Silencing ◽  
Marker Genes ◽  
Plum Pox Virus ◽  
Woody Perennials ◽  
Woody Perennial ◽  
Post Transcriptional Gene Silencing ◽  
High Level ◽  
Interfering Rna

We have shown that high-level resistance to plum pox virus (PPV) in transgenic plum clone C5 is based on post-transcriptional gene silencing (PTGS), otherwise termed RNA silencing (Scorza et al. Transgenic Res. 10:201-209, 2001). In order to more fully characterize RNA silencing in woody perennial crops, we investigated the production of short interfering RNA (siRNA) in transgenic plum clones C3 and C5, both of which harbor the capsid protein (CP) gene of PPV. We used as a control, plum PT-23, a clone only transformed with the two marker genes, NPTII and GUS. We show in the current report that C5 constitutively produces two classes of siRNA, the short (21-22 nucleotides) and long (≈27 nucleotides) species in the absence of PPV inoculation. Transgenic susceptible clone C3 and the control clone PT-23, when healthy, produce no siRNA. Upon infection, these clones produce only the short siRNA (21-22 nt). This siRNA production suggests that plum trees naturally respond to virus infection by initiating PTGS or PTGS-like mechanisms. This study also suggests that high-level virus resistance in woody perennials may require the production of both the short and long size classes of siRNA, as are produced by the resistant C5 plum clone.

scholarly journals MicroRNAs in the skin: role in development, homoeostasis and regeneration

2017 ◽  
Vol 131 (15) ◽  
pp. 1923-1940 ◽  
Author(s):  
Steven Horsburgh ◽  
Nicola Fullard ◽  
Mathilde Roger ◽  
Abbie Degnan ◽  
Stephen Todryk ◽  
...  
Keyword(s):  
Therapeutic Interventions ◽  
Transcriptional Gene Silencing ◽  
Biological Functions ◽  
Vast Number ◽  
Regulate Gene Expression ◽  
Post Transcriptional Gene Silencing ◽  
Non Coding Rnas ◽  
And Function ◽  
Molecular Signals

The skin is the largest organ of the integumentary system and possesses a vast number of functions. Due to the distinct layers of the skin and the variety of cells which populate each, a tightly regulated network of molecular signals control development and regeneration, whether due to programmed cell termination or injury. MicroRNAs (miRs) are a relatively recent discovery; they are a class of small non-coding RNAs which possess a multitude of biological functions due to their ability to regulate gene expression via post-transcriptional gene silencing. Of interest, is that a plethora of data demonstrates that a number of miRs are highly expressed within the skin, and are evidently key regulators of numerous vital processes to maintain non-aberrant functioning. Recently, miRs have been targeted as therapeutic interventions due to the ability of synthetic ‘antagomiRs’ to down-regulate abnormal miR expression, thereby potentiating wound healing and attenuating fibrotic processes which can contribute to disease such as systemic sclerosis (SSc). This review will provide an introduction to the structure and function of the skin and miR biogenesis, before summarizing the literature pertaining to the role of miRs. Finally, miR therapies will also be discussed, highlighting important future areas of research.

scholarly journals The Immunity Regulator BAK1 Contributes to Resistance Against Diverse RNA Viruses

2013 ◽  
Vol 26 (11) ◽  
pp. 1271-1280 ◽  
Author(s):  
Camilla Julie Kørner ◽  
Dominik Klauser ◽  
Annette Niehl ◽  
Ana Domínguez-Ferreras ◽  
Delphine Chinchilla ◽  
...  
Keyword(s):  
Rna Viruses ◽  
Transcriptional Gene Silencing ◽  
Dependent Manner ◽  
Antiviral Defense ◽  
Defense Gene Expression ◽  
Defense Gene ◽  
Resistance Proteins ◽  
Post Transcriptional Gene Silencing ◽  
Effector Triggered Immunity ◽  
Molecular Patterns

The plant's innate immune system detects potential biotic threats through recognition of microbe-associated molecular patterns (MAMPs) or danger-associated molecular patterns (DAMPs) by pattern recognition receptors (PRR). A central regulator of pattern-triggered immunity (PTI) is the BRI1-associated kinase 1 (BAK1), which undergoes complex formation with PRR upon ligand binding. Although viral patterns inducing PTI are well known from animal systems, nothing similar has been reported for plants. Rather, antiviral defense in plants is thought to be mediated by post-transcriptional gene silencing of viral RNA or through effector-triggered immunity, i.e., recognition of virus-specific effectors by resistance proteins. Nevertheless, infection by compatible viruses can also lead to the induction of defense gene expression, indicating that plants may also recognize viruses through PTI. Here, we show that PTI, or at least the presence of the regulator BAK1, is important for antiviral defense of Arabidopsis plants. Arabidopsis bak1 mutants show increased susceptibility to three different RNA viruses during compatible interactions. Furthermore, crude viral extracts but not purified virions induce several PTI marker responses in a BAK1-dependent manner. Overall, we conclude that BAK1-dependent PTI contributes to antiviral resistance in plants.

scholarly journals Perspectives of RNAi studies in plant pathogenic fungi

2016 ◽  
Vol 14 (1) ◽  
pp. 157-168
Author(s):  
Nguyễn Bảo Quốc ◽  
Nguyễn Ngọc Bảo Châu
Keyword(s):  
Rna Silencing ◽  
Molecular Mechanisms ◽  
Plant Protection ◽  
Pathogenic Fungi ◽  
Transcriptional Gene Silencing ◽  
Agricultural Industry ◽  
Global Food Security ◽  
Post Transcriptional Gene Silencing ◽  
Intrinsic Roles ◽  
Potential Applications

RNA silencing, the phenomenon known as RNA interference (RNAi), co-suppression or post-transcriptional gene silencing (PTGS) and quelling, has become more popular in studies of its intrinsic roles and applications in many organisms or of gene functions in a whole genomic scale. Since the discovery of RNA silencing more two decades ago, this powerful technology has demonstrated its applicability in developing RNAi-based drugs for various diseases in human. RNA silencing is also of interest in basic and applied studies in agriculture, especially in plant protection to create crop varieties that are resistant to biotic and abiotic stresses. This review provides an overview of RNA silencing studies in filamentous fungi, the molecular mechanisms of RNA silencing in fungi, and also describes potential applications in plant protection potentially important for the agricultural industry and for global food security.

scholarly journals Distinct expression, localization and function of two Rab7 proteins encoded by paralogous genes in a free-living model eukaryote.

2011 ◽  
Vol 58 (4) ◽  
Author(s):  
Magdalena Osińska ◽  
Jolanta Wiejak ◽  
Emilia Wypych ◽  
Henryk Bilski ◽  
Rafał Bartosiewicz ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Pcr Analysis ◽  
Transcriptional Gene Silencing ◽  
Post Translational Modification ◽  
Paralogous Genes ◽  
Post Transcriptional Gene Silencing ◽  
2D Gel ◽  
And Function ◽  
Microtubular Structures ◽  
Confocal And Electron Microscopy

Rab7 GTPases are involved in membrane trafficking in the late endosomal/lysosomal pathway. In Paramecium octaurelia Rab7a and Rab7b are encoded by paralogous genes. Antipeptide antibodies generated against divergent C-termini recognize Rab7a of 22.5 kDa and Rab7b of 25 kDa, respectively. In 2D gel electrophoresis two immunoreactive spots were identified for Rab7b at pI about 6.34 and about 6.18 and only one spot for Rab7a of pI about 6.34 suggesting post-translational modification of Rab7b. Mass spectrometry revealed eight identical phosphorylated residues in the both proteins. ProQ Emerald staining and ConA overlay of immunoprecipitated Rab7b indicated its putative glycosylation that was further supported by a faster electrophoretic mobility of this protein upon deglycosylation. Such a post-translational modification and substitution of Ala(140) in Rab7a for Ser(140) in Rab7b may result in distinct targeting to the oral apparatus where Rab7b associates with the microtubular structures as revealed by STED confocal and electron microscopy. Rab7a was mapped to phagosomal compartment. Absolute qReal-Time PCR analysis revealed that expression of Rab7a was 2.6-fold higher than that of Rab7b. Upon latex internalization it was further 2-fold increased for Rab7a and only slightly for Rab7b. Post-transcriptional gene silencing of rab7a suppressed phagosome formation by 70 % and impaired their acidification. Ultrastructural analysis with double immunogold labeling revealed that this effect was due to the lack of V-ATPase recruitment to phagolysosomes. No significant phenotype changes were noticed in cells upon rab7b silencing. In conclusion, Rab7b acquired a new function, whereas Rab7a can be assigned to the phagolysosomal pathway.

scholarly journals Effects of the Crinivirus Coat Protein–Interacting Plant Protein SAHH on Post-Transcriptional RNA Silencing and Its Suppression

2013 ◽  
Vol 26 (9) ◽  
pp. 1004-1015 ◽  
Author(s):  
M. Carmen Cañizares ◽  
Rosa Lozano-Durán ◽  
Tomás Canto ◽  
Eduardo R. Bejarano ◽  
David M. Bisaro ◽  
...  
Keyword(s):  
Coat Protein ◽  
Rna Silencing ◽  
Rna Degradation ◽  
Plant Viruses ◽  
Plant Protein ◽  
Transcriptional Gene Silencing ◽  
Small Interfering Rnas ◽  
Post Transcriptional Gene Silencing ◽  
Secondary Sirnas ◽  
Tomato Chlorosis Virus

In plants, post-transcriptional gene silencing (PTGS) is a sequence-specific mechanism of RNA degradation induced by double-stranded RNA (dsRNA), which is processed into small interfering RNAs (siRNAs). siRNAs are methylated and, thereby, stabilized by the activity of the S-adenosylmethionine-dependent RNA methyltransferase HEN1. PTGS is amplified by host-encoded RNA-dependent RNA polymerases (RDR), which generate dsRNA that is processed into secondary siRNAs. To counteract this RNA silencing-mediated response of the host, plant viruses express proteins with silencing suppression activity. Here, we report that the coat protein (CP) of crinivirus (family Closteroviridae, genus Crinivirus) Tomato chlorosis virus, a known suppressor of silencing, interacts with S-adenosylhomocysteine hydrolase (SAHH), a plant protein essential for sustaining the methyl cycle and S-adenosylmethionine-dependent methyltransferase activity. Our results show that, by contributing to an increased accumulation of secondary siRNAs generated by the action of RDR6, SAHH enhances local RNA silencing. Although downregulation of SAHH prevents local silencing, it enhances the spread of systemic silencing. Our results also show that SAHH is important in the suppression of local RNA silencing not only by the crinivirus Tomato chlorosis virus CP but also by the multifunctional helper component-proteinase of the potyvirus Potato virus Y.

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