scholarly journals Molecular mechanisms of Dicer: endonuclease and enzymatic activity

2017 ◽  
Vol 474 (10) ◽  
pp. 1603-1618 ◽  
Author(s):  
Min-Sun Song ◽  
John J. Rossi
Keyword(s):  
Enzymatic Activity ◽  
Small Rna ◽  
Small Rnas ◽  
Small Interfering Rna ◽  
Molecular Mechanisms ◽  
Cellular Processes ◽  
Interfering Rna ◽  
Exogenous Substrates

The enzyme Dicer is best known for its role as a riboendonuclease in the small RNA pathway. In this canonical role, Dicer is a critical regulator of the biogenesis of microRNA and small interfering RNA, as well as a growing number of additional small RNAs derived from various sources. Emerging evidence demonstrates that Dicer's endonuclease role extends beyond the generation of small RNAs; it is also involved in processing additional endogenous and exogenous substrates, and is becoming increasingly implicated in regulating a variety of other cellular processes, outside of its endonuclease function. This review will describe the canonical and newly identified functions of Dicer.

scholarly journals Salient Genetic Notes on Small-RNAs and their Applications in Agricultural Biotechnology

2020 ◽  
pp. 1-17
Author(s):  
Samuel Amiteye
Keyword(s):  
Gene Regulation ◽  
Small Rna ◽  
Small Rnas ◽  
Small Interfering Rna ◽  
Crop Improvement ◽  
Regulation Of Gene Expression ◽  
Healthy Plant ◽  
Biological Processes ◽  
Protein Coding ◽  
Interfering Rna

Small-RNAs are 20 to 27 nucleotides long non-protein-coding RNAs that act on either DNA or RNA to effect the regulation of gene expression. Small-RNAs are key in genetic and epigenetic regulation of diverse biological processes and pathways in response to biotic and abiotic environmental stresses. The gene regulatory functions of small-RNA molecules enhance healthy plant growth and normal development by controlling biological processes such as flowering programming, fruit development, disease and pests resistance. Small-RNAs comprise mainly microRNA and small interfering RNA species. MicroRNAs have been proven to primarily engage in posttranscriptional gene regulation while small interfering RNA have been implicated mainly in transcriptional gene regulation. This review covers the recent advancements in small-RNA research in plants, with emphasis on particularly microRNAs and small interfering RNA biogenesis, biological functions and their relevance in the regulation of traits of agronomic importance in plants. Also discussed extensively is the potential biotechnological applications of these small-RNAs for crop improvement.

scholarly journals Small RNA Functions as a Trafficking Effector in Plant Immunity

2019 ◽  
Vol 20 (11) ◽  
pp. 2816 ◽  
Author(s):  
Chen Zhu ◽  
Ting Liu ◽  
Ya-Nan Chang ◽  
Cheng-Guo Duan
Keyword(s):  
Small Rna ◽  
Stress Responses ◽  
Small Rnas ◽  
Plant Immunity ◽  
Arms Race ◽  
Abiotic And Biotic Stress ◽  
Plant Adaptation ◽  
Cellular Processes ◽  
Challenging Environment ◽  
Rna Export

Small RNAs represent a class of small but powerful agents that regulate development and abiotic and biotic stress responses during plant adaptation to a constantly challenging environment. Previous findings have revealed the important roles of small RNAs in diverse cellular processes. The recent discovery of bidirectional trafficking of small RNAs between different kingdoms has raised many interesting questions. The subsequent demonstration of exosome-mediated small RNA export provided a possible tool for further investigating how plants use small RNAs as a weapon during the arms race between plant hosts and pathogens. This review will focus on discussing the roles of small RNAs in plant immunity in terms of three aspects: the biogenesis of extracellular small RNAs and the transportation and trafficking small RNA-mediated gene silencing in pathogens.

scholarly journals Small RNA molecules in the regulation of spermatogenesis

Reproduction ◽  
2009 ◽  
Vol 137 (6) ◽  
pp. 901-911 ◽  
Author(s):  
Zuping He ◽  
Maria Kokkinaki ◽  
Disha Pant ◽  
G Ian Gallicano ◽  
Martin Dym
Keyword(s):  
Small Rna ◽  
Small Rnas ◽  
Molecular Mechanisms ◽  
Small Interfering Rnas ◽  
Rna Molecules ◽  
Open Questions ◽  
Complex Process ◽  
Potential Applications ◽  
Pachytene Spermatocytes ◽  
Mitotic Proliferation

Small RNA molecules (small RNAs), including small interfering RNAs (siRNAs), microRNAs (miRNAs), and piwi-interacting RNAs (piRNAs), have recently emerged as important regulators of gene expression at the post-transcriptional or translation level. Significant progress has recently been made utilizing small RNAs in elucidating the molecular mechanisms regulating spermatogenesis. Spermatogenesis is a complex process that involves the division and eventual differentiation of spermatogonial stem cells into mature spermatozoa. The process of spermatogenesis is composed of several phases: mitotic proliferation of spermatogonia to produce spermatocytes; two meiotic divisions of spermatocytes to generate haploid round spermatids; and spermiogenesis, the final phase that involves the maturation of early-round spermatids into elongated mature spermatids. A number of miRNAs are expressed abundantly in male germ cells throughout spermatogenesis, while piRNAs are only present in pachytene spermatocytes and round spermatids. In this review, we first address the synthesis, mechanisms of action, and functions of siRNA, miRNA, and piRNA, and then we focus on the recent advancements in defining the small RNAs in the regulation of spermatogenesis. Concerns pertaining to the use of siRNAs in exploring spermatogenesis mechanisms and open questions in miRNAs and piRNAs in this field are highlighted. The potential applications of small RNAs to male contraception and treatment for male infertility and testicular cancer are also discussed.

scholarly journals CCR4-NOT Deadenylates mRNA Associated with RNA-Induced Silencing Complexes in Human Cells

2010 ◽  
Vol 30 (6) ◽  
pp. 1486-1494 ◽  
Author(s):  
Xianghua Piao ◽  
Xue Zhang ◽  
Ligang Wu ◽  
Joel G. Belasco
Keyword(s):  
Small Rna ◽  
Small Interfering Rna ◽  
Inhibitory Effect ◽  
Human Cells ◽  
Predominant Role ◽  
Catalytic Subunits ◽  
Present Evidence ◽  
Mrna Targets ◽  
Protein Components ◽  
Interfering Rna

ABSTRACT MicroRNAs (miRNAs) repress gene expression posttranscriptionally by inhibiting translation and by expediting deadenylation so as to trigger rapid mRNA decay. Their regulatory influence is mediated by the protein components of the RNA-induced silencing complex (RISC), which deliver miRNAs and siRNAs to their mRNA targets. Here, we present evidence that CCR4-NOT is the deadenylase that removes poly(A) from messages destabilized by miRNAs in human cells. Overproducing a mutationally inactivated form of either of the catalytic subunits of this deadenylase (CCR4 or CAF1/POP2) significantly impedes the deadenylation and decay of mRNA targeted by a partially complementary miRNA. The same deadenylase initiates the degradation of “off-target” mRNAs that are bound by an imperfectly complementary siRNA introduced by transfection. The greater inhibitory effect of inactive CAF1 or POP2 (versus inactive CCR4) suggests a predominant role for this catalytic subunit of CCR4-NOT in miRNA- or small interfering RNA (siRNA)-mediated deadenylation. These effects of mi/siRNAs and CCR4-NOT can be fully reproduced by directly tethering RISC to mRNA without the guidance of a small RNA, indicating that the ability of RISC to accelerate deadenylation is independent of RNA base pairing. Despite its importance for mi/siRNA-mediated deadenylation, CCR4-NOT appears not to associate significantly with RISC, as judged by the failure of CAF1 and POP2 to coimmunoprecipitate detectably with either the Ago or TNRC6 subunit of RISC, a finding at odds with deadenylase recruitment as the mechanism by which RISC accelerates poly(A) removal.

scholarly journals Molecular mechanisms that funnel RNA precursors into endogenous small-interfering RNA and microRNA biogenesis pathways in Drosophila

RNA ◽  
2010 ◽  
Vol 16 (3) ◽  
pp. 506-515 ◽  
Author(s):  
K. Miyoshi ◽  
T. Miyoshi ◽  
J. V. Hartig ◽  
H. Siomi ◽  
M. C. Siomi
Keyword(s):  
Small Interfering Rna ◽  
Molecular Mechanisms ◽  
Microrna Biogenesis ◽  
Interfering Rna

scholarly journals Twist Modulates Human Trophoblastic Cell Invasion via Regulation of N-Cadherin

Endocrinology ◽  
2012 ◽  
Vol 153 (2) ◽  
pp. 925-936 ◽  
Author(s):  
York Hunt Ng ◽  
Hua Zhu ◽  
Peter C. K. Leung
Keyword(s):  
Cell Invasion ◽  
Small Interfering Rna ◽  
Molecular Mechanisms ◽  
Dependent Manner ◽  
Trophoblastic Cell ◽  
Protein Levels ◽  
Bewo Cells ◽  
Interfering Rna ◽  
Tgf Β1

The invasion of extravillous cytotrophoblasts (EVT) into the underlying maternal tissues and vasculature is a key step in human placentation. The molecular mechanisms involved in the development of the invasive phenotype of EVT include many that were first discovered for their role in cancer cell metastasis. Previous studies have demonstrated that N-cadherin and its regulatory transcription factor Twist play important roles in the onset and progression of cancers, but their roles in human trophoblastic cell invasion is not clear. The goal of the study was to examine the role of Twist and N-cadherin in human trophoblastic cell invasion. Twist and N-cadherin mRNA and protein levels were determined by RT-PCR and Western blotting in human placental tissues, highly invasive EVT, and poorly invasive JEG-3 and BeWo cells. Whether IL-1β and TGF-β1 regulate Twist mRNA and protein levels in the EVT was also examined. A small interfering RNA strategy was employed to determine the role of Twist and N-cadherin in HTR-8/SVneo cell invasion. Matrigel assays were used to assess cell invasion. Twist and N-cadherin were highly expressed in EVT but were poorly expressed in JEG-3 and BeWo cells. IL-1β and TGF-β1 differentially regulated Twist expression in EVT in a time- and concentration-dependent manner. Small interfering RNA specific for Twist decreased N-cadherin and reduced invasion of HTR-8/SVneo cells. Similarly, a reduction in N-cadherin decreased the invasive capacity of HTR-8/SVneo cells. Twist is an upstream regulator of N-cadherin-mediated invasion of human trophoblastic cells.

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.

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