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Journal Cover Wiley Interdisciplinary Reviews : RNA
  [SJR: 4.563]   [H-I: 36]   [3 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Online) 1757-7012
   Published by John Wiley and Sons Homepage  [1582 journals]
  • Issue information
    • PubDate: 2017-04-21T08:57:22.293793-05:
      DOI: 10.1002/wrna.1389
       
  • Cover Image, Volume 8, Issue 3
    • Authors: Lauren A. Woodward; Justin W. Mabin, Pooja Gangras, Guramrit Singh
      Abstract: The cover image, by Lauren A.Woodward et al., is based on Advanced Review The exon junction complex: a lifelong guardian of mRNA fate,
      DOI : 10.1002/wrna.1411.The cover image, by Lauren A.Woodward et al., is based on Advanced Review The exon junction complex: a lifelong guardian of mRNA fate,
      DOI : 10.1002/wrna.1411.
      PubDate: 2017-04-21T08:57:21.098171-05:
       
  • Insights into RNA structure and dynamics from recent NMR and X-ray studies
           of the Neurospora Varkud satellite ribozyme
    • Authors: Pierre Dagenais; Nicolas Girard, Eric Bonneau, Pascale Legault
      Abstract: Despite the large number of noncoding RNAs and their importance in several biological processes, our understanding of RNA structure and dynamics at atomic resolution is still very limited. Like many other RNAs, the Neurospora Varkud satellite (VS) ribozyme performs its functions through dynamic exchange of multiple conformational states. More specifically, the VS ribozyme recognizes and cleaves its stem-loop substrate via a mechanism that involves several structural transitions within its stem-loop substrate. The recent publications of high-resolution structures of the VS ribozyme, obtained by NMR spectroscopy and X-ray crystallography, offer an opportunity to integrate the data and closely examine the structural and dynamic properties of this model RNA system. Notably, these investigations provide a valuable example of the divide-and-conquer strategy for structural and dynamic characterization of a large RNA, based on NMR structures of several individual subdomains. The success of this divide-and-conquer approach reflects the modularity of RNA architecture and the great care taken in identifying the independently-folding modules. Together with previous biochemical and biophysical characterizations, the recent NMR and X-ray studies provide a coherent picture into how the VS ribozyme recognizes its stem-loop substrate. Such in-depth characterization of this RNA enzyme will serve as a model for future structural and engineering studies of dynamic RNAs and may be particularly useful in planning divide-and-conquer investigations.For further resources related to this article, please visit the WIREs website.Recent structural studies provide an atomic view of substrate recognition and cleavage by the VS ribozyme.
      PubDate: 2017-04-06T03:58:34.22102-05:0
      DOI: 10.1002/wrna.1421
       
  • Functional diversity of Arabidopsis organelle-localized RNA-recognition
           motif-containing proteins
    • Authors: Xiaowen Shi; Maureen R. Hanson, Stephane Bentolila
      Abstract: RNA-Binding Proteins (RBPs) play key roles in plant gene expression and regulation. RBPs contain a variety of RNA-binding motifs, the most abundant and most widespread one in eukaryotes is the RNA recognition motif (RRM). Many nucleus-encoded RRM-containing proteins are transported into chloroplasts and/or mitochondria, and participate in various RNA-related processes in plant organelles. Loss of these proteins can have a detrimental effect on some critical processes such as photosynthesis and respiration, sometimes leading to lethality. Progress has been made in the last few years in understanding the function of particular organelle-localized RRM-containing proteins. Members of the Organelle RRM protein (ORRM, some also characterized as Glycine-Rich RNA-Binding Proteins) family and the Chloroplast RiboNucleoProtein (cpRNP) family, are involved in various types of RNA metabolism, including RNA editing, RNA stability and RNA processing. Organelle-localized RRM proteins also function in plant development and stress responses, in some conditions acting as protein or RNA chaperones. There has been recent progress in characterizing the function of organelle-localized RRM proteins in RNA-related processes and how RRM proteins contribute to the normal growth and development of plants.For further resources related to this article, please visit the WIREs website.Organelle-localized RRM proteins participate in a variety of RNA-related processes, which consequently alters expression of many genes. Many organelle-localized RRM proteins are also involved in plant stress response and/or plant development. However, the association between these processes still awaits investigation.
      PubDate: 2017-03-29T21:45:30.678635-05:
      DOI: 10.1002/wrna.1420
       
  • Box C/D small nucleolar RNA genes and the Prader-Willi syndrome: a complex
           interplay
    • Authors: Jérôme Cavaillé
      Abstract: The nucleolus of mammalian cells contains hundreds of box C/D small nucleolar RNAs (SNORDs). Through their ability to base pair with ribosomal RNA precursors, most play important roles in the synthesis and/or activity of ribosomes, either by guiding sequence-specific 2′-O-methylations or by facilitating RNA folding and cleavages. A growing number of SNORD genes with elusive functions have been discovered recently. Intriguingly, the vast majority of them are located in two large, imprinted gene clusters at human chromosome region 15q11q13 (the SNURF–SNRPN domain) and at 14q32 (the DLK1–DIO3 domain) where they are expressed, respectively, only from the paternally and maternally inherited alleles. These placental mammal-specific SNORD genes have many features of the canonical SNORDs that guide 2′-O-methylations, yet they lack obvious complementarity with ribosomal RNAs and, surprisingly, they are processed from large, tandemly repeated genes expressed preferentially in the brain. This review summarizes our understanding of the biology of these peculiar SNORD genes, focusing particularly on SNORD115 and SNORD116 in the SNURF–SNRPN domain. It examines the growing evidence that altered levels of these SNORDs and/or their host-gene transcripts may be a primary cause of Prader-Willi syndrome (PWS; a rare disorder characterized by overeating and obesity) as well as abnormalities in signaling through the 5-HT2C serotonin receptor. Finally, the hypothesis that PWS may be a ribosomopathy (ribosomal disease) is also discussed.For further resources related to this article, please visit the WIREs website.The imprinted gene cluster at 15q11q13.
      PubDate: 2017-03-13T21:10:37.832566-05:
      DOI: 10.1002/wrna.1417
       
  • Cell cycle RNA regulons coordinating early lymphocyte development
    • Authors: Alison Galloway; Martin Turner
      Abstract: Lymphocytes undergo dynamic changes in gene expression as they develop from progenitor cells lacking antigen receptors, to mature cells that are prepared to mount immune responses. While transcription factors have established roles in lymphocyte development, they act in concert with post-transcriptional and post-translational regulators to determine the proteome. Furthermore, the post-transcriptional regulation of RNA regulons consisting of mRNAs whose protein products act cooperatively allows RNA binding proteins to exert their effects at multiple points in a pathway. Here, we review recent evidence demonstrating the importance of RNA binding proteins that control the cell cycle in lymphocyte development and discuss the implications for tumorigenesis.For further resources related to this article, please visit the WIREs website.RNA binding proteins influence the expression of cell cycle regulators, which then in turn affects the balance of cell cycle progression and V(D)J recombination in developing lymphocytes. In this review, we discuss how RNA binding protein (RBP) regulates the cell cycle and other pathways in developing lymphocytes.
      PubDate: 2017-02-23T19:35:27.697468-05:
      DOI: 10.1002/wrna.1419
       
  • Microexons: discovery, regulation, and function
    • Authors: Dmytro Ustianenko; Sebastien M. Weyn-Vanhentenryck, Chaolin Zhang
      Abstract: The importance of RNA splicing in numerous cellular processes is well established. However, an underappreciated aspect is the ability of the spliceosome to recognize a set of very small (3–30 nucleotide, 1–10 amino acid) exons named microexons. Despite their small size, microexons and their regulation through alternative splicing have now been shown to play critical roles in protein and system function. Here we review the discovery of microexons over time and the mechanisms by which their splicing is regulated, including recent progress made through deep RNA sequencing. We also discuss the functional role of microexons in biology and disease.For further resources related to this article, please visit the WIREs website.A snapshot of microexon regulation and their ability to modulate protein properties, including mechanistic links to disease.
      PubDate: 2017-02-11T02:30:28.448862-05:
      DOI: 10.1002/wrna.1418
       
  • RNA in extracellular vesicles
    • Authors: Kyoung Mi Kim; Kotb Abdelmohsen, Maja Mustapic, Dimitrios Kapogiannis, Myriam Gorospe
      Abstract: Cells release a range of membrane-enclosed extracellular vesicles (EVs) into the environment. Among them, exosomes and microvesicles (collectively measuring 40–1000 nm in diameter) carry proteins, signaling lipids, and nucleic acids from donor cells to recipient cells, and thus have been proposed to serve as intercellular mediators of communication. EVs transport cellular materials in many physiologic processes, including differentiation, stem cell homeostasis, immune responses, and neuronal signaling. EVs are also increasingly recognized as having a direct role in pathologies such as cancer and neurodegeneration. Accordingly, EVs have been the focus of intense investigation as biomarkers of disease, prognostic indicators, and even therapeutic tools. Here, we review the classes of RNAs present in EVs, both coding RNAs (messenger RNAs) and noncoding RNAs (long noncoding RNAs, microRNAs, and circular RNAs). The rising attention to EV-resident RNAs as biomarkers stems from the fact that RNAs can be detected at extremely low quantities using a number of methods. To illustrate the interest in EV biology, we discuss EV RNAs in cancer and neurodegeneration, two major age-associated disease processes.For further resources related to this article, please visit the WIREs website.Extracellular vesicles (EVs) contain different RNA species, including messenger RNAs (mRNAs), microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and Circular RNAs (cirRNAs). These cargo RNAs may affect gene expression patterns in recipient cells and/or serve as diagnostic and prognostic markers.
      PubDate: 2017-01-28T03:15:37.47873-05:0
      DOI: 10.1002/wrna.1413
       
  • microRNA-binding proteins: specificity and function
    • Authors: Richard W. Zealy; Samuel P. Wrenn, Sylvia Davila, Kyung-Won Min, Je-Hyun Yoon
      Abstract: microRNA (miRNA) and RNA-binding proteins (RBPs) have been studied widely in post-transcriptional gene regulation. Previous work has focused on defining how miRNA and RBPs modulate target mRNA decay and translation as well as investigating how they interplay each other. Emerging studies indicate that certain RBPs other than the AGO-family proteins directly interact with mature miRNAs. These findings implicate competitive binding of RBPs to target miRNAs, sequestration of miRNAs from AGO, promotion of AGO binding to miRNAs, and transfer of miRNAs from RBPs to AGO. Recent work also indicates that AGO-free cytoplasmic miRNAs establish complexes with novel miRNA-binding proteins (miRBPs). This review covers the recent discovery of novel miRBPs, offering a new perspective on the miRNA-mediated gene silencing mechanism.For further resources related to this article, please visit the WIREs website.miRNA-binding proteins (miRBPs) cooperate or compete with AGO2 for miRNA binding in miRNA-mediated gene silencing.
      PubDate: 2017-01-28T02:35:30.731682-05:
      DOI: 10.1002/wrna.1414
       
  • Structures of RNA repeats associated with neurological diseases
    • Authors: Leszek Błaszczyk; Wojciech Rypniewski, Agnieszka Kiliszek
      Abstract: All RNA molecules possess a ‘propensity’ to fold into complex secondary and tertiary structures. Although they are composed of only four types of nucleotides, they show an enormous structural richness which reflects their diverse functions in the cell. However, in some cases the folding of RNA can have deleterious consequences. Aberrantly expanded, repeated RNA sequences can exhibit gain-of-function abnormalities and become pathogenic, giving rise to many incurable neurological diseases. Most RNA repeats form long hairpin structures whose stem consists of noncanonical base pairs interspersed among Watson–Crick pairs. The expanded hairpins have an ability to sequester important proteins and form insoluble nuclear foci. The RNA pathology, common to many repeat disorders, has drawn attention to the structures of the RNA repeats. In this review, we summarize secondary structure probing and crystallographic studies of disease-related RNA repeat sequences. We discuss the unique structural features which can contribute to the pathogenic properties of the repeated runs. In addition, we present the newest reports concerning structural data linked to therapeutic approaches.For further resources related to this article, please visit the WIREs website.Crystallographic structures of RNA repeats associated with neurological disorders.
      PubDate: 2017-01-28T02:10:44.596532-05:
      DOI: 10.1002/wrna.1412
       
  • mRNA localization as a rheostat to regulate subcellular gene expression
    • Authors: Nevraj S. Kejiou; Alexander F. Palazzo
      Abstract: It is currently believed that certain messenger RNAs (mRNAs) are localized to distinct subcellular regions to efficiently target their encoded proteins. However, this simplistic model does not explain why in certain scenarios mRNA localization is dispensable for proper protein distribution. In other cases, mRNA localization is accompanied by translational silencing and degradation by the localization machinery. Here we propose that in certain scenarios mRNAs are localized so that they can either be stabilized and translated, or silenced and degraded, in response to the needs of the subcellular locale. In these cases, the localized mRNA, and its cadre of associated factors, act as a rheostat that regulates protein production and/or mRNA stability in response to the needs of its immediate subcellular environment.For further resources related to this article, please visit the WIREs website.Each localized mRNAs receives input from its subcellular locale and responds as a rheostat to output new proteins to meet local demands.
      PubDate: 2017-01-24T21:45:32.277306-05:
      DOI: 10.1002/wrna.1416
       
  • Regulation of mRNA following brain ischemia and reperfusion
    • Authors: Donald J. DeGracia
      Abstract: There is growing appreciation that mRNA regulation plays important roles in disease and injury. mRNA regulation and ribonomics occur in brain ischemia and reperfusion (I/R) following stroke and cardiac arrest and resuscitation. It was recognized over 40 years ago that translation arrest (TA) accompanies brain I/R and is now recognized as part of the intrinsic stress responses triggered in neurons. However, neuron death correlates to a prolonged TA in cells fated to undergo delayed neuronal death (DND). Dysfunction of mRNA regulatory processes in cells fated to DND prevents them from translating stress-induced mRNAs such as heat shock proteins. The morphological and biochemical studies of mRNA regulation in postischemic neurons are discussed in the context of the large variety of molecular damage induced by ischemic injury. Open issues and areas of future investigation are highlighted. A sober look at the molecular complexity of ischemia-induced neuronal injury suggests that a network framework will assist in making sense of this complexity. The ribonomic network sits between the gene network and the various protein and metabolic networks. Thus, targeting the ribonomic network may prove more effective at neuroprotection than targeting specific molecular pathways, for which all efforts have failed to the present time to stop DND in stroke and after cardiac arrest.For further resources related to this article, please visit the WIREs website.Dramatic image of CA3 neuron after 10-min brain ischemia and 1-h reperfusion shows redistribution of HuR (red) and polyadenylated mRNAs (green).
      PubDate: 2017-01-17T23:55:50.354326-05:
      DOI: 10.1002/wrna.1415
       
  • Bioinformatic tools for analysis of CLIP ribonucleoprotein data
    • Authors: Supriyo De; Myriam Gorospe
      Abstract: Investigating the interactions of RNA-binding proteins (RBPs) with RNAs is a complex task for molecular and computational biologists. The molecular biology techniques and the computational approaches to understand RBP–RNA (or ribonucleoprotein, RNP) interactions have advanced considerably over the past few years and numerous and diverse software tools have been developed to analyze these data. Accordingly, laboratories interested in RNP biology face the challenge of choosing adequately among the available software tools those that best address the biological problem they are studying. Here, we focus on state-of-the-art molecular biology techniques that employ crosslinking and immunoprecipitation (CLIP) of an RBP to study and map RNP interactions. We review the different software tools and databases available to analyze the most widely used CLIP methods, HITS-CLIP, PAR-CLIP, and iCLIP.Overview of CLIP-Seq analysis, from the isolation of cellular RNPs to the identification and analysis of RBP-bound RNA segments using the bioinformatic tools described in this review.
      PubDate: 2016-12-23T00:31:16.732754-05:
      DOI: 10.1002/wrna.1404
       
  • The exon junction complex: a lifelong guardian of mRNA fate
    • Authors: Lauren A. Woodward; Justin W. Mabin, Pooja Gangras, Guramrit Singh
      Abstract: During messenger RNA (mRNA) biogenesis and processing in the nucleus, many proteins are imprinted on mRNAs assembling them into messenger ribonucleoproteins (mRNPs). Some of these proteins remain stably bound within mRNPs and have a long-lasting impact on their fate. One of the best-studied examples is the exon junction complex (EJC), a multiprotein complex deposited primarily 24 nucleotides upstream of exon–exon junctions as a consequence of pre-mRNA splicing. The EJC maintains a stable, sequence-independent, hold on the mRNA until its removal during translation in the cytoplasm. Acting as a molecular shepherd, the EJC travels with mRNA across the cellular landscape coupling pre-mRNA splicing to downstream, posttranscriptional processes such as mRNA export, mRNA localization, translation, and nonsense-mediated mRNA decay (NMD). In this review, we discuss our current understanding of the EJC’s functions during these processes, and expound its newly discovered functions (e.g., pre-mRNA splicing). Another focal point is the recently unveiled in vivo EJC interactome, which has shed new light on the EJC's location on the spliced RNAs and its intimate relationship with other mRNP components. We summarize new strides being made in connecting the EJC’s molecular function with phenotypes, informed by studies of human disorders and model organisms. The progress toward understanding EJC functions has revealed, in its wake, even more questions, which are discussed throughout.For further resources related to this article, please visit the WIREs website.Assembly, structure, and function of the Exon Junction Complex (EJC).
      PubDate: 2016-12-23T00:06:42.359406-05:
      DOI: 10.1002/wrna.1411
       
  • Long noncoding RNAs in the p53 network
    • Authors: Ritu Chaudhary; Ashish Lal
      Abstract: The tumor-suppressor protein p53 is activated in response to numerous cellular stresses including DNA damage. p53 functions primarily as a sequence-specific transcription factor that controls the expression of hundreds of protein-coding genes and noncoding RNAs, including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs). While the role of protein-coding genes and miRNAs in mediating the effects of p53 has been extensively studied, the physiological function and molecular mechanisms by which p53-regulated lncRNAs act is beginning to be understood. In this review, we discuss recent studies on lncRNAs that are directly or indirectly regulated by p53 and how they contribute to the biological outcomes of p53 activation.For further resources related to this article, please visit the WIREs website.DNA damage is known to induce cell cycle arrest, apoptosis and senescence via protein-coding genes that are direct targets of p53. In addition, noncoding RNAs such as miRNAs (e.g., miR-34a) and lncRNAs (e.g., PANDA, Pint, LincRNA-p21and LED) mediate these effects of p53 by regulating a subset of p53 targets that control cell cycle arrest, apoptosis and senescence.
      PubDate: 2016-12-19T02:27:08.266471-05:
      DOI: 10.1002/wrna.1410
       
  • Current progress on microRNAs-based therapeutics in neurodegenerative
           diseases
    • Authors: Patrícia Pereira; João A. Queiroz, Ana Figueiras, Fani Sousa
      Abstract: MicroRNAs (miRNAs)-based therapy has recently emerged as a promising strategy in the treatments of neurodegenerative diseases. Thus, in this review, the most recent and important challenges and advances on the development of miRNA therapeutics for brain targeting are discussed. In particular, this review highlights current knowledge and progress in the field of manufacturing, recovery, isolation, purification, and analysis of these therapeutic oligonucleotides. Finally, the available miRNA delivery systems are reviewed and an analysis is presented in what concerns to the current challenges that have to be addressed to ensure their specificity and efficacy. Overall, it is intended to provide a perspective on the future of miRNA-based therapeutics, focusing the biotechnological approach to obtain miRNAs.For further resources related to this article, please visit the WIREs website.Barriers to in vivo microRNAs delivery
      PubDate: 2016-11-24T00:46:10.722175-05:
      DOI: 10.1002/wrna.1409
       
  • Unwinding the twister ribozyme: from structure to mechanism
    • Authors: Jennifer Gebetsberger; Ronald Micura
      Abstract: The twister ribozyme motif has been identified by bioinformatic means very recently. Currently, four crystal structures with ordered active sites together with a series of chemical and biochemical data provide insights into how this RNA accomplishes its efficient self-cleavage. Of particular interest for a mechanistic proposal are structural distinctions observed in the active sites that concern the conformation of the U-A cleavage site dinucleotide (in-line alignment of the attacking 2′-O nucleophile to the to-be-cleaved PO5′ bond versus suboptimal alignments) as well as the presence/absence of Mg2+ ions at the scissile phosphate. All structures support the notion that an active site guanine and the conserved adenine at the cleavage site are important contributors to cleavage chemistry, likely being involved in general acid base catalysis. Evidence for innersphere coordination of a Mg2+ ion to the pro-S nonbridging oxygen of the scissile phosphate stems from two of the four crystal structures. Together with the finding of thio/rescue effects for phosphorothioate substrates, this suggests the participation of divalent ions in the overall catalytic strategy employed by twister ribozymes. In this context, it is notable that twister retains wild-type activity when the phylogenetically conserved stem P1 is deleted, able to cleave a single nucleotide only.For further resources related to this article, please visit the WIREs website.Small self-cleaving ribozymes perform the same internal transesterification reaction although possessing distinct folds and active sites. They can employ four strategies to catalyze phosphordiester cleavage indicated by colored arrows (left panel; for explanation see main text). Close-up view of the env22 twister ribozyme active site (right panel; pdb: 4RGE). The to-be-cleaved dinucleotide unit is shown in yellow. Guanine (G48) and adenine (A6) together with Mg2+ are likely the key players for twister ribozyme catalysis.
      PubDate: 2016-11-14T01:35:38.417735-05:
      DOI: 10.1002/wrna.1402
       
  • Regulation of mRNA turnover in cystic fibrosis lung disease
    • Authors: Roopa Biswas; Parameet Kumar, Harvey B. Pollard
      Abstract: Cystic fibrosis (CF) is an autosomal recessive disease due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, F508del-CFTR being the most frequent mutation. The CF lung is characterized by a hyperinflammatory phenotype and is regulated by multiple factors that coordinate its pathophysiology. In CF the expression of CFTR as well as proinflammatory genes are regulated at the level of messenger RNA (mRNA) stability, which subsequently affect translation. These mechanisms are mediated by inflammatory RNA-binding proteins as well as small endogenous noncoding microRNAs, in coordination with cellular signaling pathways. These regulatory factors exhibit altered expression and function in vivo in the CF lung, and play a key role in the pathophysiology of CF lung disease. In this review, we have described the role of mRNA stability and associated regulatory mechanisms in CF lung disease.For further resources related to this article, please visit the WIREs website.Various trans-factors (RNA-binding proteins and/or miRNAs) interact with cis-elements on the mRNA 3′-UTR sequences and regulate the expression of F508del-CFTR and proinflammatory chemokine and cytokine genes (like IL-8 and IL-6) in the cystic fibrosis airway. The concerted effect of these factors and the resulting complex regulatory network regulate the CF disease phenotype.
      PubDate: 2016-11-13T20:55:23.36762-05:0
      DOI: 10.1002/wrna.1408
       
  • How to understand atomistic molecular dynamics simulations of RNA and
           protein–RNA complexes'
    • Authors: Jiří Šponer; Miroslav Krepl, Pavel Banáš, Petra Kührová, Marie Zgarbová, Petr Jurečka, Marek Havrila, Michal Otyepka
      Abstract: We provide a critical assessment of explicit-solvent atomistic molecular dynamics (MD) simulations of RNA and protein/RNA complexes, written primarily for non-specialists with an emphasis to explain the limitations of MD. MD simulations can be likened to hypothetical single-molecule experiments starting from single atomistic conformations and investigating genuine thermal sampling of the biomolecules. The main advantage of MD is the unlimited temporal and spatial resolution of positions of all atoms in the simulated systems. Fundamental limitations are the short physical time-scale of simulations, which can be partially alleviated by enhanced-sampling techniques, and the highly approximate atomistic force fields describing the simulated molecules. The applicability and present limitations of MD are demonstrated on studies of tetranucleotides, tetraloops, ribozymes, riboswitches and protein/RNA complexes. Wisely applied simulations respecting the approximations of the model can successfully complement structural and biochemical experiments.For further resources related to this article, please visit the WIREs website.MD simulations allow to study structural dynamics, flexibility, hydration, ion-binding, base substitutions and other properties based on available atomistic experimental structures of RNAs and protein-RNA complexes.
      PubDate: 2016-11-10T21:05:36.086057-05:
      DOI: 10.1002/wrna.1405
       
  • Posttranscriptional coordination of splicing and miRNA biogenesis in
           plants
    • Authors: Agata Stepien; Katarzyna Knop, Jakub Dolata, Michal Taube, Mateusz Bajczyk, Maria Barciszewska-Pacak, Andrzej Pacak, Artur Jarmolowski, Zofia Szweykowska-Kulinska
      Abstract: MicroRNAs (miRNAs) are short, single-stranded, noncoding RNAs that play a crucial role in basic physiological and morphological processes and in response to various stresses in eukaryotic organisms. However, the miRNA biogenesis, which is based on the action of complex protein machinery, varies between plants and animals, with the differences largely concerning the location of the process, the protein composition of the microprocessor, the mechanism of miRNA action on mRNA target, and the miRNA gene (MIR) structure. Roughly half of known Arabidopsis MIRs contain introns, and 29 miRNAs are encoded within the introns of host genes. Selection of alternative transcription start sites, alternative splice sites (SSs), and polyadenylation sites has been identified within miRNA primary transcripts (pri-miRNAs), and such variety is essential for the production and fine-tuning of miRNA levels. For example, the posttranscriptional processing of intron-containing pri-miRNAs involves the action of additional RNA metabolism machineries, such as the spliceosome and polyadenylation machinery, and to a large extent is based on direct communication between SERRATE (one of the core components of the plant microprocessor) and U1 snRNP auxiliary proteins. Moreover, the position of the miRNA stem–loop structure relative to the closest active 5′SS is essential for the miRNA production efficiency. Indeed, it is highly probable that this pre-miRNA location affects recruitment of the microprocessor to pri-miRNAs and therefore influences miRNA maturation and target mRNA regulation. Such complicated crosstalk between several machineries is important for a proper miRNA-connected response to biotic and abiotic stresses, ensuring plant survival in a changing environment.For further resources related to this article, please visit the WIREs website.The crosstalk between transcription, splicing, polyadenylation and miRNA biogenesis machineries in the regulation of plant miRNA level.
      PubDate: 2016-11-09T15:32:14.553927-05:
      DOI: 10.1002/wrna.1403
       
  • New evolutionary insights into the non-enzymatic origin of RNA oligomers
    • Authors: Judit E. Šponer; Jiří Šponer, Ernesto Di Mauro
      Abstract: We outline novel findings on the non-enzymatic polymerization of nucleotides under plausible prebiotic conditions and on the spontaneous onset of informational complexity in the founding molecule, RNA. We argue that the unique ability of 3′, 5′ cyclic guanosine monophosphate to form stacked architectures and polymerize in a self-sustained manner suggests that this molecule may serve as the ‘seed of life’ from which all self-replicating oligonucleotides can be derived via a logically complete sequence of simple events.For further resources related to this article, please visit the WIREs website.The formamide-based funnel model we present in this work outlines a straightforward path from primordial molecules to catalytically active oligonucleotides.
      PubDate: 2016-10-26T21:55:30.648078-05:
      DOI: 10.1002/wrna.1400
       
 
 
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