scholarly journals The Evolutionary Significance of RNAi in the Fungal Kingdom

2020 ◽  
Vol 21 (24) ◽  
pp. 9348
Author(s):  
Carlos Lax ◽  
Ghizlane Tahiri ◽  
José Alberto Patiño-Medina ◽  
José T. Cánovas-Márquez ◽  
José A. Pérez-Ruiz ◽  
...  
Keyword(s):  
Target Genes ◽  
Regulation Of Gene Expression ◽  
Genome Integrity ◽  
Evolutionary Significance ◽  
Messenger Rnas ◽  
Small Interfering Rnas ◽  
Rnase Iii ◽  
Double Stranded Rna ◽  
Main Component ◽  
Fungal Kingdom

RNA interference (RNAi) was discovered at the end of last millennium, changing the way scientists understood regulation of gene expression. Within the following two decades, a variety of different RNAi mechanisms were found in eukaryotes, reflecting the evolutive diversity that RNAi entails. The essential silencing mechanism consists of an RNase III enzyme called Dicer that cleaves double-stranded RNA (dsRNA) generating small interfering RNAs (siRNAs), a hallmark of RNAi. These siRNAs are loaded into the RNA-induced silencing complex (RISC) triggering the cleavage of complementary messenger RNAs by the Argonaute protein, the main component of the complex. Consequently, the expression of target genes is silenced. This mechanism has been thoroughly studied in fungi due to their proximity to the animal phylum and the conservation of the RNAi mechanism from lower to higher eukaryotes. However, the role and even the presence of RNAi differ across the fungal kingdom, as it has evolved adapting to the particularities and needs of each species. Fungi have exploited RNAi to regulate a variety of cell activities as different as defense against exogenous and potentially harmful DNA, genome integrity, development, drug tolerance, or virulence. This pathway has offered versatility to fungi through evolution, favoring the enormous diversity this kingdom comprises.

scholarly journals Targeted gene suppression through double-stranded RNA application using easy-to-use methods in Arabidopsis thaliana

2022 ◽  
Vol 65 (1) ◽  
Author(s):  
Minsu Park ◽  
Tae Young Um ◽  
Geupil Jang ◽  
Yang Do Choi ◽  
Chanseok Shin
Keyword(s):  
Arabidopsis Thaliana ◽  
Target Genes ◽  
Fluorescent Protein ◽  
Specific Interaction ◽  
Mrna Levels ◽  
Messenger Rnas ◽  
Small Interfering Rnas ◽  
Double Stranded Rna ◽  
Reverse Transcription Pcr ◽  
Green Fluorescent

AbstractRNA interference (RNAi) is an RNA-dependent gene silencing process that is regulated by the interaction between the RNA-induced silencing complex (RISC) and double-stranded RNA (dsRNA). Exogenous dsRNAs are imported directly into the cytoplasm, where they are cleaved by Dicer into short dsRNA fragments of 20–25 base pairs. These short dsRNA fragments, called small interfering RNAs (siRNAs) have sequence-specific interaction with target genes. The guide strand, onto which siRNAs are incorporated in the RISC interacts with the target mRNA sequence, thereby inducing cleavage and degradation of target messenger RNAs (mRNAs) by ribonucleases. Recent studies have shown that plant dsRNA treatments can induce RNAi. However, the dsRNA application methods and delivery systems involved have not been well examined. In this study, dsRNA was introduced to Arabidopsis thaliana by two methods: dipping and spray. We synthesized two dsRNAs designed to target mRNAs encoding enhanced green fluorescent protein (EGFP). After applying dsRNAs that target EGFP, we found an obvious reduction in GFP expression. This was determined using fluorescence microscopy and quantitative reverse transcription PCR to assess the mRNA levels of the auxin-sensitive reporter DR5-EGFP Arabidopsis thaliana. Our data revealed that applying target gene-specific exogenous dsRNAs can induce suppression of target genes of interest whether the dipping or spray method is used. This study therefore provides a foundation for understanding how to apply and deliver dsRNAs in plants.

scholarly journals MicroRNA-independent roles of the RNase III enzymes Drosha and Dicer

Open Biology ◽  
2013 ◽  
Vol 3 (10) ◽  
pp. 130144 ◽  
Author(s):  
Timothy M. Johanson ◽  
Andrew M. Lew ◽  
Mark M. W. Chong
Keyword(s):  
Ribosomal Rna ◽  
Messenger Rnas ◽  
Small Interfering Rnas ◽  
Rnase Iii ◽  
Ribonuclease Iii ◽  
Stem Loop ◽  
Viral Rnas ◽  
Genome Regulation ◽  
Many Sources ◽  
Stem Cell Populations

The ribonuclease III enzymes Drosha and Dicer are renowned for their central roles in the biogenesis of microRNAs (miRNAs). For many years, this has overshadowed the true versatility and importance of these enzymes in the processing of other RNA substrates. For example, Drosha also recognizes and cleaves messenger RNAs (mRNAs), and potentially ribosomal RNA. The cleavage of mRNAs occurs via recognition of secondary stem-loop structures similar to miRNA precursors, and is an important mechanism of repressing gene expression, particularly in progenitor/stem cell populations. On the other hand, Dicer also has critical roles in genome regulation and surveillance. These include the production of endogenous small interfering RNAs from many sources, and the degradation of potentially harmful short interspersed element and viral RNAs. These findings have sparked a renewed interest in these enzymes, and their diverse functions in biology.

scholarly journals Posttranscriptional gene silencing in nuclei

2010 ◽  
Vol 108 (1) ◽  
pp. 409-414 ◽  
Author(s):  
Paul Hoffer ◽  
Sergey Ivashuta ◽  
Olga Pontes ◽  
Alexa Vitins ◽  
Craig Pikaard ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Target Genes ◽  
Rna Degradation ◽  
Small Interfering Rnas ◽  
Double Stranded Rna ◽  
Posttranscriptional Gene Silencing ◽  
Subcellular Compartmentation ◽  
Specific Degradation ◽  
Precursor Mrna ◽  
Specific Sequences

In plants, small interfering RNAs (siRNAs) with sequence homology to transcribed regions of genes can guide the sequence-specific degradation of corresponding mRNAs, leading to posttranscriptional gene silencing (PTGS). The current consensus is that siRNA-mediated PTGS occurs primarily in the cytoplasm where target mRNAs are localized and translated into proteins. However, expression of an inverted-repeat double-stranded RNA corresponding to the soybeanFAD2-1Adesaturase intron is sufficient to silenceFAD2-1, implicating nuclear precursor mRNA (pre-mRNA) rather than cytosolic mRNA as the target of PTGS. SilencingFAD2-1using intronic or 3′-UTR sequences does not affect transcription rates of the target genes but results in the strong reduction of target transcript levels in the nucleus. Moreover, siRNAs corresponding to pre-mRNA–specific sequences accumulate in the nucleus. In Arabidopsis, we find that two enzymes involved in PTGS, Dicer-like 4 and RNA-dependent RNA polymerase 6, are localized in the nucleus. Collectively, these results demonstrate that siRNA-directed RNA degradation can take place in the nucleus, suggesting the need for a more complex view of the subcellular compartmentation of PTGS in plants.

scholarly journals Maternal small RNAs mediate spatial-temporal regulation of gene expression, imprinting, and seed development in Arabidopsis

2019 ◽  
Vol 116 (7) ◽  
pp. 2761-2766 ◽  
Author(s):  
Ryan C. Kirkbride ◽  
Jie Lu ◽  
Changqing Zhang ◽  
Rebecca A. Mosher ◽  
David C. Baulcombe ◽  
...  
Keyword(s):  
Gene Expression ◽  
Seed Development ◽  
Seed Coat ◽  
Target Genes ◽  
Expression Patterns ◽  
Regulation Of Gene Expression ◽  
Small Interfering Rnas ◽  
Altered Expression ◽  
Temporal Regulation ◽  
Laser Capture

Arabidopsis seed development involves maternal small interfering RNAs (siRNAs) that induce RNA-directed DNA methylation (RdDM) through the NRPD1-mediated pathway. To investigate their biological functions, we characterized siRNAs in the endosperm and seed coat that were separated by laser-capture microdissection (LCM) in reciprocal genetic crosses with an nrpd1 mutant. We also monitored the spatial-temporal activity of the NRPD1-mediated pathway on seed development using the AGO4:GFP::AGO4 (promoter:GFP::protein) reporter and promoter:GUS sensors of siRNA-mediated silencing. From these approaches, we identified four distinct groups of siRNA loci dependent on or independent of the maternal NRPD1 allele in the endosperm or seed coat. A group of maternally expressed NRPD1-siRNA loci targets endosperm-preferred genes, including those encoding AGAMOUS-LIKE (AGL) transcription factors. Using translational promoter:AGL::GUS constructs as sensors, we demonstrate that spatial and temporal expression patterns of these genes in the endosperm are regulated by the NRPD1-mediated pathway irrespective of complete silencing (AGL91) or incomplete silencing (AGL40) of these target genes. Moreover, altered expression of these siRNA-targeted genes affects seed size. We propose that the corresponding maternal siRNAs could account for parent-of-origin effects on the endosperm in interploidy and hybrid crosses. These analyses reconcile previous studies on siRNAs and imprinted gene expression during seed development.

scholarly journals Gene Regulation Mediated by microRNA-Triggered Secondary Small RNAs in Plants

Plants ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 112 ◽  
Author(s):  
Felipe Fenselau de Felippes
Keyword(s):  
Gene Regulation ◽  
Small Rnas ◽  
Target Genes ◽  
Regulation Of Gene Expression ◽  
Small Interfering Rnas ◽  
Expression Of Genes ◽  
Secondary Sirnas ◽  
In Trans ◽  
Production Pattern ◽  
In Cis

In plants, proper development and response to abiotic and biotic stimuli requires an orchestrated regulation of gene expression. Small RNAs (sRNAs) are key molecules involved in this process, leading to downregulation of their target genes. Two main classes of sRNAs exist, the small interfering RNAs (siRNAs) and microRNAs (miRNAs). The role of the latter class in plant development and physiology is well known, with many examples of how miRNAs directly impact the expression of genes in cells where they are produced, with dramatic consequences to the life of the plant. However, there is an aspect of miRNA biology that is still poorly understood. In some cases, miRNA targeting can lead to the production of secondary siRNAs from its target. These siRNAs, which display a characteristic phased production pattern, can act in cis, reinforcing the initial silencing signal set by the triggering miRNA, or in trans, affecting genes that are unrelated to the initial target. In this review, the mechanisms and implications of this process in the gene regulation mediated by miRNAs will be discussed. This work will also explore techniques for gene silencing in plants that are based on this unique pathway.

scholarly journals Dicer Functions in Aquatic Species

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Yasuko Kitagishi ◽  
Naoko Okumura ◽  
Hitomi Yoshida ◽  
Chika Tateishi ◽  
Yuri Nishimura ◽  
...  
Keyword(s):  
Recent Progress ◽  
Defense Mechanism ◽  
Aquatic Species ◽  
Small Interfering Rnas ◽  
Rnase Iii ◽  
Catalytic Subunits ◽  
Double Stranded Rna ◽  
Related Research ◽  
Micro Rnas ◽  
Endogenous Genes

Dicer is an RNase III enzyme with two catalytic subunits, which catalyzes the cleavage of double-stranded RNA to small interfering RNAs and micro-RNAs, which are mainly involved in invasive nucleic acid defense and endogenous genes regulation. Dicer is abundantly expressed in embryos, indicating the importance of the protein in early embryonic development. In addition, Dicer is thought to be involved in defense mechanism against foreign nucleic acids such as viruses. This paper will mainly focus on the recent progress of Dicer-related research and discuss potential RNA interference pathways in aquatic species.

scholarly journals Contribution of Small RNA Pathway to Interactions of Rice with Pathogens and Insect Pests

Rice ◽  
2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Qin Feng ◽  
Yan Li ◽  
Zhi-Xue Zhao ◽  
Wen-Ming Wang
Keyword(s):  
Small Rna ◽  
Small Rnas ◽  
Recent Progress ◽  
Target Genes ◽  
Insect Pests ◽  
Circular Rnas ◽  
Small Interfering Rnas ◽  
Double Stranded Rna ◽  
Argonaute Proteins ◽  
Non Coding Rnas

AbstractSmall RNAs (sRNAs) are mainly classified into microRNAs (miRNAs) and small interfering RNAs (siRNAs) according to their origin. miRNAs originate from single-stranded RNA precursors, whereas siRNAs originate from double-stranded RNA precursors that are synthesized by RNA-dependent RNA polymerases. Both of single-stranded and double-stranded RNA precursors are processed into sRNAs by Dicer-like proteins. Then, the sRNAs are loaded into ARGONAUTE proteins, forming RNA-induced silencing complexes (RISCs). The RISCs repress the expression of target genes with sequences complementary to the sRNAs through the cleavage of transcripts, the inhibition of translation or DNA methylation. Here, we summarize the recent progress of sRNA pathway in the interactions of rice with various parasitic organisms, including fungi, viruses, bacteria, as well as insects. Besides, we also discuss the hormone signal in sRNA pathway, and the emerging roles of circular RNAs and long non-coding RNAs in rice immunity. Obviously, small RNA pathway may act as a part of rice innate immunity to coordinate with growth and development.

Abiotic Stress Tolerance in Soybean : Regulated by ncRNA

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
YASIN JESHIMA KHAN ◽  
HUSNARA Tyagi ◽  
Anil kumar Singh ◽  
Santosh kumar. Magadum
Keyword(s):  
Abiotic Stresses ◽  
Target Genes ◽  
Abiotic Stress Tolerance ◽  
Crop Improvement ◽  
Vital Role ◽  
Grain Legume ◽  
Biological Processes ◽  
Small Interfering Rnas ◽  
Cellular Environment ◽  
Non Coding Rnas

Plants respond through a cascade of reactions resulting in varied cellular environment leading to alterations in the patterns of protein expression resulting in phonotypic changes. Single cell genomics and global proteomics came out to be powerful tools and efficient techniques in studying stress tolerant plants. Non-coding RNAs are a distinct class of regulatory RNAs in plants and animals that control a variety of biological processes. Small ncRNAs play a vital role in post transcriptional gene regulation by either translational repression or by inducing mRNA cleavage. The major classes of small RNAs include microRNAs (miRNAs) and small interfering RNAs (siRNAs), which differ in their biogenesis. miRNAs control the expression of cognate target genes by binding to complementary sequences, resulting in cleavage or translational inhibition of the target RNAs. siRNAs too have a similar structure, function, and biogenesis like miRNAs but are derived from long double-stranded RNAs and can often direct DNA methylation at target sequences.In this review, we focus on the involvement of ncRNAs in comabting abiotic stresses of soybean. This review emphasis on previously known miRNAs as they play important role in several abiotic stresses like drought, salinity, chilling and heat stress by their diverse roles in mediating biological processes like gene expression, chromatin formation, defense of genome against invading viruses. This review attempts to elucidate the various kinds of non-coding RNAs explored, their discovery, biogenesis, functions, and response for different type of abiotic stresses and future aspects for crop improvement in the context of soybean, a representative grain legume.

scholarly journals The Non-Canonical Aspects of MicroRNAs: Many Roads to Gene Regulation

Cells ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1465 ◽  
Author(s):  
Christiaan J. Stavast ◽  
Stefan J. Erkeland
Keyword(s):  
Rna Polymerase Ii ◽  
Transcriptional Activation ◽  
Small Rnas ◽  
Target Genes ◽  
Biological Functions ◽  
Rnase Iii ◽  
Mrna Targets ◽  
Argonaute Proteins ◽  
Epigenetic Modifiers ◽  
Encoding Genes

MicroRNAs (miRNAs) are critical regulators of gene expression. As miRNAs are frequently deregulated in many human diseases, including cancer and immunological disorders, it is important to understand their biological functions. Typically, miRNA-encoding genes are transcribed by RNA Polymerase II and generate primary transcripts that are processed by RNase III-endonucleases DROSHA and DICER into small RNAs of approximately 21 nucleotides. All miRNAs are loaded into Argonaute proteins in the RNA-induced silencing complex (RISC) and act as post-transcriptional regulators by binding to the 3′- untranslated region (UTR) of mRNAs. This seed-dependent miRNA binding inhibits the translation and/or promotes the degradation of mRNA targets. Surprisingly, recent data presents evidence for a target-mediated decay mechanism that controls the level of specific miRNAs. In addition, several non-canonical miRNA-containing genes have been recently described and unexpected functions of miRNAs have been identified. For instance, several miRNAs are located in the nucleus, where they are involved in the transcriptional activation or silencing of target genes. These epigenetic modifiers are recruited by RISC and guided by miRNAs to specific loci in the genome. Here, we will review non-canonical aspects of miRNA biology, including novel regulators of miRNA expression and functions of miRNAs in the nucleus.

scholarly journals Direct Interactions with Nascent Transcripts Is Potentially a Common Targeting Mechanism of Long Non-Coding RNAs

Genes ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1483
Author(s):  
Ivan Antonov ◽  
Yulia Medvedeva
Keyword(s):  
Target Genes ◽  
Regulation Of Gene Expression ◽  
Pilot Project ◽  
Base Pairing ◽  
Nascent Transcript ◽  
Active Transcription ◽  
Wet Lab ◽  
In Trans ◽  
Non Coding Rnas ◽  
Nascent Transcripts

Although thousands of mammalian long non-coding RNAs (lncRNAs) have been reported in the last decade, their functional annotation remains limited. A wet-lab approach to detect functions of a novel lncRNA usually includes its knockdown followed by RNA sequencing and identification of the deferentially expressed genes. However, identification of the molecular mechanism(s) used by the lncRNA to regulate its targets frequently becomes a challenge. Previously, we developed the ASSA algorithm that detects statistically significant inter-molecular RNA-RNA interactions. Here we designed a workflow that uses ASSA predictions to estimate the ability of an lncRNA to function via direct base pairing with the target transcripts (co- or post-transcriptionally). The workflow was applied to 300+ lncRNA knockdown experiments from the FANTOM6 pilot project producing statistically significant predictions for 71 unique lncRNAs (104 knockdowns). Surprisingly, the majority of these lncRNAs were likely to function co-transcriptionally, i.e., hybridize with the nascent transcripts of the target genes. Moreover, a number of the obtained predictions were supported by independent iMARGI experimental data on co-localization of lncRNA and chromatin. We detected an evolutionarily conserved lncRNA CHASERR (AC013394.2 or LINC01578) that could regulate target genes co-transcriptionally via interaction with a nascent transcript by directing CHD2 helicase. The obtained results suggested that this nuclear lncRNA may be able to activate expression of the target genes in trans by base-pairing with the nascent transcripts and directing the CHD2 helicase to the regulated promoters leading to open the chromatin and active transcription. Our study highlights the possible importance of base-pairing between nuclear lncRNAs and nascent transcripts for the regulation of gene expression.

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