Hyeshik Chang

MiRNAs play important roles in many diseases including cancers. However computational prediction of miRNA target genes is challenging and the accuracies of existing methods remain poor. We report mirMark, a new machine learning-based method of miRNA target prediction at the site- and UTR-levels. This method uses experimentally verified miRNA targets from miRecords and mirTarBase as training sets and considers over 700 features. By combining Correlation-based Feature Selection with a variety of statistical or machine learning methods for the site- and UTR-level classifiers, mirMark significantly improves the overall predictive performance compared to existing publicly available methods. MirMark is available from https://github.com/lanagarmire/MirMark.

Filed under: Media, Talks

Ernesto Picardi, Anna Maria D'Erchia, Angela Gallo, Antonio Montalvo and Graziano Pesole

Topographical transcriptome mapping of the mouse medial ganglionic eminence by spatially-resolved RNA-seq.

Genome Biol. 2014 Oct 25;15(10):486

Authors: Zechel S, Zajac P, Lönnerberg P, Ibáñez CF, Linnarsson S

Abstract
BackgroundCortical interneurons originating from the medial ganglionic eminence, MGE, are among the most diverse cells within the CNS. Different pools of proliferating progenitor cells are thought to exist in the ventricular zone of the MGE, but whether the underlying subventricular and mantle regions of the MGE are spatially patterned has not yet been addressed. Here, we combined laser-capture microdissection and multiplex RNA-sequencing to map the transcriptome of MGE cells at a spatial resolution of 50 ¿m.ResultsDistinct groups of progenitor cells showing different stages of interneuron maturation are identified and topographically mapped based on their genome-wide transcriptional pattern. Although proliferating potential decreased rather abruptly outside the ventricular zone, a ventro-lateral gradient of increasing migratory capacity was identified, revealing heterogeneous cell populations within this neurogenic structure.ConclusionsWe demonstrate that spatially resolved RNA-seq is ideally suited for high resolution topographical mapping of genome-wide gene expression in heterogeneous anatomical structures such as the mammalian central nervous system.

PMID: 25344199 [PubMed - as supplied by publisher]

Reassessment of the Role of TSC, mTORC1 and MicroRNAs in Amino Acids-Meditated Translational Control of TOP mRNAs.

PLoS One. 2014;9(10):e109410

Authors: Patursky-Polischuk I, Kasir J, Miloslavski R, Hayouka Z, Hausner-Hanochi M, Stolovich-Rain M, Tsukerman P, Biton M, Mudhasani R, Jones SN, Meyuhas O

Abstract
TOP mRNAs encode components of the translational apparatus, and repression of their translation comprises one mechanism, by which cells encountering amino acid deprivation downregulate the biosynthesis of the protein synthesis machinery. This mode of regulation involves TSC as knockout of TSC1 or TSC2 rescued TOP mRNAs translation in amino acid-starved cells. The involvement of mTOR in translational control of TOP mRNAs is demonstrated by the ability of constitutively active mTOR to relieve the translational repression of TOP mRNA upon amino acid deprivation. Consistently, knockdown of this kinase as well as its inhibition by pharmacological means blocked amino acid-induced translational activation of these mRNAs. The signaling of amino acids to TOP mRNAs involves RagB, as overexpression of active RagB derepressed the translation of these mRNAs in amino acid-starved cells. Nonetheless, knockdown of raptor or rictor failed to suppress translational activation of TOP mRNAs by amino acids, suggesting that mTORC1 or mTORC2 plays a minor, if any, role in this mode of regulation. Finally, miR10a has previously been suggested to positively regulate the translation of TOP mRNAs. However, we show here that titration of this microRNA failed to downregulate the basal translation efficiency of TOP mRNAs. Moreover, Drosha knockdown or Dicer knockout, which carries out the first and second processing steps in microRNAs biosynthesis, respectively, failed to block the translational activation of TOP mRNAs by amino acid or serum stimulation. Evidently, these results are questioning the positive role of microRNAs in this mode of regulation.

PMID: 25338081 [PubMed - as supplied by publisher]

Related Articles

Computational detection and suppression of sequence-specific off-target phenotypes from whole genome RNAi screens.

Nucleic Acids Res. 2014;42(13):8214-22

Authors: Zhong R, Kim J, Kim HS, Kim M, Lum L, Levine B, Xiao G, White MA, Xie Y

Abstract
A challenge for large-scale siRNA loss-of-function studies is the biological pleiotropy resulting from multiple modes of action of siRNA reagents. A major confounding feature of these reagents is the microRNA-like translational quelling resulting from short regions of oligonucleotide complementarity to many different messenger RNAs. We developed a computational approach, deconvolution analysis of RNAi screening data, for automated quantitation of off-target effects in RNAi screening data sets. Substantial reduction of off-target rates was experimentally validated in five distinct biological screens across different genome-wide siRNA libraries. A public-access graphical-user-interface has been constructed to facilitate application of this algorithm.

PMID: 24972830 [PubMed - indexed for MEDLINE]

Related Articles

RNAi screening comes of age: improved techniques and complementary approaches.

Nat Rev Mol Cell Biol. 2014 Sep;15(9):591-600

Authors: Mohr SE, Smith JA, Shamu CE, Neumüller RA, Perrimon N

Abstract
Gene silencing through sequence-specific targeting of mRNAs by RNAi has enabled genome-wide functional screens in cultured cells and in vivo in model organisms. These screens have resulted in the identification of new cellular pathways and potential drug targets. Considerable progress has been made to improve the quality of RNAi screen data through the development of new experimental and bioinformatics approaches. The recent availability of genome-editing strategies, such as the CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 system, when combined with RNAi, could lead to further improvements in screen data quality and follow-up experiments, thus promoting our understanding of gene function and gene regulatory networks.

PMID: 25145850 [PubMed - indexed for MEDLINE]

Related Articles

RBBP6 isoforms regulate the human polyadenylation machinery and modulate expression of mRNAs with AU-rich 3' UTRs.

Genes Dev. 2014 Oct 15;28(20):2248-60

Authors: Di Giammartino DC, Li W, Ogami K, Yashinskie JJ, Hoque M, Tian B, Manley JL

Abstract
Polyadenylation of mRNA precursors is mediated by a large multisubunit protein complex. Here we show that RBBP6 (retinoblastoma-binding protein 6), identified initially as an Rb- and p53-binding protein, is a component of this complex and functions in 3' processing in vitro and in vivo. RBBP6 associates with other core factors, and this interaction is mediated by an unusual ubiquitin-like domain, DWNN ("domain with no name"), that is required for 3' processing activity. The DWNN is also expressed, via alternative RNA processing, as a small single-domain protein (isoform 3 [iso3]). Importantly, we show that iso3, known to be down-regulated in several cancers, competes with RBBP6 for binding to the core machinery, thereby inhibiting 3' processing. Genome-wide analyses following RBBP6 knockdown revealed decreased transcript levels, especially of mRNAs with AU-rich 3' untranslated regions (UTRs) such as c-Fos and c-Jun, and increased usage of distal poly(A) sites. Our results implicate RBBP6 and iso3 as novel regulators of 3' processing, especially of RNAs with AU-rich 3' UTRs.

PMID: 25319826 [PubMed - in process]

Rational experiment design for sequencing-based RNA structure mapping.

RNA. 2014 Oct 20;

Authors: Aviran S, Pachter L

Abstract
Structure mapping is a classic experimental approach for determining nucleic acid structure that has gained renewed interest in recent years following advances in chemistry, genomics, and informatics. The approach encompasses numerous techniques that use different means to introduce nucleotide-level modifications in a structure-dependent manner. Modifications are assayed via cDNA fragment analysis, using electrophoresis or next-generation sequencing (NGS). The recent advent of NGS has dramatically increased the throughput, multiplexing capacity, and scope of RNA structure mapping assays, thereby opening new possibilities for genome-scale, de novo, and in vivo studies. From an informatics standpoint, NGS is more informative than prior technologies by virtue of delivering direct molecular measurements in the form of digital sequence counts. Motivated by these new capabilities, we introduce a novel model-based in silico approach for quantitative design of large-scale multiplexed NGS structure mapping assays, which takes advantage of the direct and digital nature of NGS readouts. We use it to characterize the relationship between controllable experimental parameters and the precision of mapping measurements. Our results highlight the complexity of these dependencies and shed light on relevant tradeoffs and pitfalls, which can be difficult to discern by intuition alone. We demonstrate our approach by quantitatively assessing the robustness of SHAPE-Seq measurements, obtained by multiplexing SHAPE (selective 2'-hydroxyl acylation analyzed by primer extension) chemistry in conjunction with NGS. We then utilize it to elucidate design considerations in advanced genome-wide approaches for probing the transcriptome, which recently obtained in vivo information using dimethyl sulfate (DMS) chemistry.

PMID: 25332375 [PubMed - as supplied by publisher]

A new microscope allows three-dimensional imaging of living systems at very high resolution in real time. Authors: Bi-Chang Chen, Wesley R. Legant, Kai Wang, Lin Shao, Daniel E. Milkie, Michael W. Davidson, Chris Janetopoulos, Xufeng S. Wu, John A. Hammer, Zhe Liu, Brian P. English, Yuko Mimori-Kiyosue, Daniel P. Romero, Alex T. Ritter, Jennifer Lippincott-Schwartz, Lillian Fritz-Laylin, R. Dyche Mullins, Diana M. Mitchell, Joshua N. Bembenek, Anne-Cecile Reymann, Ralph Böhme, Stephan W. Grill, Jennifer T. Wang, Geraldine Seydoux, U. Serdar Tulu, Daniel P. Kiehart, Eric Betzig

3' UTR Length and Messenger Ribonucleoprotein Composition Determine Endocleavage Efficiencies at Termination Codons.

Cell Rep. 2014 Oct 7;

Authors: Boehm V, Haberman N, Ottens F, Ule J, Gehring NH

Abstract
Nonsense-mediated mRNA decay (NMD) degrades different classes of mRNAs, including transcripts with premature termination codons (PTCs). The NMD factor SMG6 initiates degradation of substrate mRNAs by endonucleolytic cleavage. Here, we aim to delineate the cascade of NMD-activating events that culminate in endocleavage. We report that long 3' UTRs elicit SMG6-mediated endonucleolytic degradation. The presence of an exon-junction complex (EJC) within the 3' UTR strongly stimulates endocleavage in a distance-independent manner. The interaction of SMG6 with EJCs is not required for endocleavage. Whereas the core NMD component UPF2 supports endonucleolytic decay of long 3' UTR mRNAs, it is mostly dispensable during EJC-stimulated endocleavage. Using high-throughput sequencing, we map endocleavage positions of different PTC-containing reporter mRNAs and an endogenous NMD substrate to regions directly at and downstream of the termination codon. These results reveal how messenger ribonucleoprotein (mRNP) parameters differentially influence SMG6-executed endonucleolysis and uncover central characteristics of this phenomenon associated with translation termination.

PMID: 25310981 [PubMed - as supplied by publisher]

Related Articles

Diverse modes of evolutionary emergence and flux of conserved microRNA clusters.

RNA. 2014 Oct 20;

Authors: Mohammed J, Siepel A, Lai EC

Abstract
Many animal miRNA loci reside in genomic clusters that generate multicistronic primary-miRNA transcripts. While clusters that contain copies of the same miRNA hairpin are clearly products of local duplications, the evolutionary provenance of clusters with disparate members is less clear. Recently, it was proposed that essentially all such clusters in Drosophila derived from de novo formation of miRNA-like hairpins within existing miRNA transcripts, and that the maintenance of multiple miRNAs in such clusters was due to evolutionary hitchhiking on a major cluster member. However, this model seems at odds with the fact that many such miRNA clusters are composed of well-conserved miRNAs. In an effort to trace the birth and expansion of miRNA clusters that are presently well-conserved across Drosophilids, we analyzed a broad swath of metazoan species, with particular emphasis on arthropod evolution. Beyond duplication and de novo birth, we highlight a diversity of modes that contribute to miRNA evolution, including neofunctionalization of miRNA copies, fissioning of locally duplicated miRNA clusters, miRNA deletion, and miRNA cluster expansion via the acquisition and/or neofunctionalization of miRNA copies from elsewhere in the genome. In particular, we suggest that miRNA clustering by acquisition represents an expedient strategy to bring cohorts of target genes under coordinate control by miRNAs that had already been individually selected for regulatory impact on the transcriptome.

PMID: 25332374 [PubMed - as supplied by publisher]

Related Articles

miR-CATCH: MicroRNA Capture Affinity Technology.

Methods Mol Biol. 2015;1218:365-73

Authors: Vencken S, Hassan T, McElvaney NG, Smith SG, Greene CM

Abstract
Several experimental methods exist to explore the microRNA (miRNA) regulome. These methods almost exclusively focus on multiple targets bound to a single, or perhaps a few miRNAs of interest. Here, we describe a microRNA capture affinity technology (miR-CATCH) which uses an affinity capture oligonucleotide to co-purify a single target messenger RNA (mRNA) together with all its endogenously bound miRNAs. This bench-top method is similar to RNA immunoprecipitation (RIP) and provides an experimental alternative to computational miRNA target prediction.

PMID: 25319664 [PubMed - in process]

Related Articles

miRseqViewer: Multi-panel visualization of sequence, structure and expression for analysis of microRNA sequencing data.

Bioinformatics. 2014 Oct 15;

Authors: Jang I, Chang H, Jun Y, Park S, Yang JO, Lee B, Kim W, Kim VN, Lee S

Abstract
Deep sequencing of small RNAs has become a routine process in recent years, but no dedicated viewer is as yet available to explore the sequence features simultaneously along with secondary structure and gene expression of microRNA (miRNA). We present a highly interactive application that visualizes the sequence alignment, secondary structure and normalized read counts in synchronous multi-panel windows. This helps users to easily examine the relationships between the structure of precursor and the sequences and abundance of final products and thereby will facilitate the studies on miRNA biogenesis and regulation. The project manager handles multiple samples of multiple groups. The read alignment is imported in BAM file format. Implemented features comprise sorting, zooming, highlighting, editing, filtering, saving, exporting, etc. Currently, miRseqViewer supports 84 organisms whose annotation is available at miRBase. Availability: miRseqViewer, implemented in Java, is available at https://github.com/insoo078/mirseqviewer or at http://msv.kobic.re.kr.
CONTACT: sanghyuk@ewha.ac.kr.

PMID: 25322835 [PubMed - as supplied by publisher]

Antiviral immunity via RIG-I-mediated recognition of RNA bearing 5′-diphosphates

Nature 514, 7522 (2014). doi:10.1038/nature13590

Authors: Delphine Goubau, Martin Schlee, Safia Deddouche, Andrea J. Pruijssers, Thomas Zillinger, Marion Goldeck, Christine Schuberth, Annemarthe G. Van der Veen, Tsutomu Fujimura, Jan Rehwinkel, Jason A. Iskarpatyoti, Winfried Barchet, Janos Ludwig, Terence S. Dermody, Gunther Hartmann & Caetano Reis e Sousa

Mammalian cells possess mechanisms to detect and defend themselves from invading viruses. In the cytosol, the RIG-I-like receptors (RLRs), RIG-I (retinoic acid-inducible gene I; encoded by DDX58) and MDA5 (melanoma differentiation-associated gene 5; encoded by IFIH1) sense atypical RNAs associated with virus infection. Detection triggers a signalling cascade via the adaptor MAVS that culminates in the production of type I interferons (IFN-α and β; hereafter IFN), which are key antiviral cytokines. RIG-I and MDA5 are activated by distinct viral RNA structures and much evidence indicates that RIG-I responds to RNAs bearing a triphosphate (ppp) moiety in conjunction with a blunt-ended, base-paired region at the 5′-end (reviewed in refs 1, 2, 3). Here we show that RIG-I also mediates antiviral responses to RNAs bearing 5′-diphosphates (5′pp). Genomes from mammalian reoviruses with 5′pp termini, 5′pp-RNA isolated from yeast L-A virus, and base-paired 5′pp-RNAs made by in vitro transcription or chemical synthesis, all bind to RIG-I and serve as RIG-I agonists. Furthermore, a RIG-I-dependent response to 5′pp-RNA is essential for controlling reovirus infection in cultured cells and in mice. Thus, the minimal determinant for RIG-I recognition is a base-paired RNA with 5′pp. Such RNAs are found in some viruses but not in uninfected cells, indicating that recognition of 5′pp-RNA, like that of 5′ppp-RNA, acts as a powerful means of self/non-self discrimination by the innate immune system.

Code share

Nature 514, 7524 (2014). doi:10.1038/514536a

Papers in Nature journals should make computer code accessible where possible.

Article

MicroRNAs play important roles in the maintenance of cellular homeostasis through the post-transcriptional regulation of gene expression. Here, the authors implicate loss of the miRNA biogenesis factor Drosha and altered miRNA maturation in tumour progression under hypoxic conditions.

Nature Communications doi: 10.1038/ncomms6202

Authors: Rajesha Rupaimoole, Sherry Y. Wu, Sunila Pradeep, Cristina Ivan, Chad V. Pecot, Kshipra M. Gharpure, Archana S. Nagaraja, Guillermo N. Armaiz-Pena, Michael McGuire, Behrouz Zand, Heather J. Dalton, Justyna Filant, Justin Bottsford Miller, Chunhua Lu, Nouara C. Sadaoui, Lingegowda S. Mangala, Morgan Taylor, Twan van den Beucken, Elizabeth Koch, Cristian Rodriguez-Aguayo, Li Huang, Menashe Bar-Eli, Bradly G. Wouters, Milan Radovich, Mircea Ivan, George A. Calin, Wei Zhang, Gabriel Lopez-Berestein, Anil K. Sood

Nature advance online publication 29 October 2014. doi:10.1038/nature13900

Authors: Jonathan T. Sczepanski & Gerald F. Joyce

Thirty years ago it was shown that the non-enzymatic, template-directed polymerization of activated mononucleotides proceeds readily in a homochiral system, but is severely inhibited by the presence of the opposing enantiomer. This finding poses a severe challenge for the spontaneous emergence of RNA-based life, and has led to the suggestion that either RNA was preceded by some other genetic polymer that is not subject to chiral inhibition or chiral symmetry was broken through chemical processes before the origin of RNA-based life. Once an RNA enzyme arose that could catalyse the polymerization of RNA, it would have been possible to distinguish among the two enantiomers, enabling RNA replication and RNA-based evolution to occur. It is commonly thought that the earliest RNA polymerase and its substrates would have been of the same handedness, but this is not necessarily the case. Replicating d- and l-RNA molecules may have emerged together, based on the ability of structured RNAs of one handedness to catalyse the templated polymerization of activated mononucleotides of the opposite handedness. Here we develop such a cross-chiral RNA polymerase, using in vitro evolution starting from a population of random-sequence RNAs. The d-RNA enzyme, consisting of 83 nucleotides, catalyses the joining of l-mono- or oligonucleotide substrates on a complementary l-RNA template, and similar behaviour occurs for the l-enzyme with d-substrates and a d-template. Chiral inhibition is avoided because the 106-fold rate acceleration of the enzyme only pertains to cross-chiral substrates. The enzyme’s activity is sufficient to generate full-length copies of its enantiomer through the templated joining of 11 component oligonucleotides.

Nature Methods 11, 1147 (2014). doi:10.1038/nmeth.3100

Authors: Ryan J Bloom, Sally M Winkler & Christina D Smolke

Nature Methods 11, 1154 (2014). doi:10.1038/nmeth.3136

Authors: Simon Ausländer, Pascal Stücheli, Charlotte Rehm, David Ausländer, Jörg S Hartig & Martin Fussenegger

Nature Methods 11, 1095 (2014). doi:10.1038/nmeth.3166

Author: Michael Eisenstein

Two surveys of the transcriptome hint at unexpected diversity in the breadth of mRNA modifications.

Nature Methods 11, 1091 (2014). doi:10.1038/nmeth.3156

Nature Genetics 46, 1160 (2014). doi:10.1038/ng.3101

Authors: Nils Weinhold, Anders Jacobsen, Nikolaus Schultz, Chris Sander & William Lee

Nature Genetics 46, 1173 (2014). doi:10.1038/ng.3097

Authors: Andrew R Wood, Tonu Esko, Jian Yang, Sailaja Vedantam, Tune H Pers, Stefan Gustafsson, Audrey Y Chu, Karol Estrada, Jian'an Luan, Zoltán Kutalik, Najaf Amin, Martin L Buchkovich, Damien C Croteau-Chonka, Felix R Day, Yanan Duan, Tove Fall, Rudolf Fehrmann, Teresa Ferreira, Anne U Jackson, Juha Karjalainen, Ken Sin Lo, Adam E Locke, Reedik Mägi, Evelin Mihailov, Eleonora Porcu, Joshua C Randall, André Scherag, Anna A E Vinkhuyzen, Harm-Jan Westra, Thomas W Winkler, Tsegaselassie Workalemahu, Jing Hua Zhao, Devin Absher, Eva Albrecht, Denise Anderson, Jeffrey Baron, Marian Beekman, Ayse Demirkan, Georg B Ehret, Bjarke Feenstra, Mary F Feitosa, Krista Fischer, Ross M Fraser, Anuj Goel, Jian Gong, Anne E Justice, Stavroula Kanoni, Marcus E Kleber, Kati Kristiansson, Unhee Lim, Vaneet Lotay, Julian C Lui, Massimo Mangino, Irene Mateo Leach, Carolina Medina-Gomez, Michael A Nalls, Dale R Nyholt, Cameron D Palmer, Dorota Pasko, Sonali Pechlivanis, Inga Prokopenko, Janina S Ried, Stephan Ripke, Dmitry Shungin, Alena Stancáková, Rona J Strawbridge, Yun Ju Sung, Toshiko Tanaka, Alexander Teumer, Stella Trompet, Sander W van der Laan, Jessica van Setten, Jana V Van Vliet-Ostaptchouk, Zhaoming Wang, Loïc Yengo, Weihua Zhang, Uzma Afzal, Johan Ärnlöv, Gillian M Arscott, Stefania Bandinelli, Amy Barrett, Claire Bellis, Amanda J Bennett, Christian Berne, Matthias Blüher, Jennifer L Bolton, Yvonne Böttcher, Heather A Boyd, Marcel Bruinenberg, Brendan M Buckley, Steven Buyske, Ida H Caspersen, Peter S Chines, Robert Clarke, Simone Claudi-Boehm, Matthew Cooper, E Warwick Daw, Pim A De Jong, Joris Deelen, Graciela Delgado, Josh C Denny, Rosalie Dhonukshe-Rutten, Maria Dimitriou, Alex S F Doney, Marcus Dörr, Niina Eklund, Elodie Eury, Lasse Folkersen, Melissa E Garcia, Frank Geller, Vilmantas Giedraitis, Alan S Go, Harald Grallert, Tanja B Grammer, Jürgen Gräßler, Henrik Grönberg, Lisette C P G M de Groot, Christopher J Groves, Jeffrey Haessler, Per Hall, Toomas Haller, Goran Hallmans, Anke Hannemann, Catharina A Hartman, Maija Hassinen, Caroline Hayward, Nancy L Heard-Costa, Quinta Helmer, Gibran Hemani, Anjali K Henders, Hans L Hillege, Mark A Hlatky, Wolfgang Hoffmann, Per Hoffmann, Oddgeir Holmen, Jeanine J Houwing-Duistermaat, Thomas Illig, Aaron Isaacs, Alan L James, Janina Jeff, Berit Johansen, Åsa Johansson, Jennifer Jolley, Thorhildur Juliusdottir, Juhani Junttila, Abel N Kho, Leena Kinnunen, Norman Klopp, Thomas Kocher, Wolfgang Kratzer, Peter Lichtner, Lars Lind, Jaana Lindström, Stéphane Lobbens, Mattias Lorentzon, Yingchang Lu, Valeriya Lyssenko, Patrik K E Magnusson, Anubha Mahajan, Marc Maillard, Wendy L McArdle, Colin A McKenzie, Stela McLachlan, Paul J McLaren, Cristina Menni, Sigrun Merger, Lili Milani, Alireza Moayyeri, Keri L Monda, Mario A Morken, Gabriele Müller, Martina Müller-Nurasyid, Arthur W Musk, Narisu Narisu, Matthias Nauck, Ilja M Nolte, Markus M Nöthen, Laticia Oozageer, Stefan Pilz, Nigel W Rayner, Frida Renstrom, Neil R Robertson, Lynda M Rose, Ronan Roussel, Serena Sanna, Hubert Scharnagl, Salome Scholtens, Fredrick R Schumacher, Heribert Schunkert, Robert A Scott, Joban Sehmi, Thomas Seufferlein, Jianxin Shi, Karri Silventoinen, Johannes H Smit, Albert Vernon Smith, Joanna Smolonska, Alice V Stanton, Kathleen Stirrups, David J Stott, Heather M Stringham, Johan Sundström, Morris A Swertz, Ann-Christine Syvänen, Bamidele O Tayo, Gudmar Thorleifsson, Jonathan P Tyrer, Suzanne van Dijk, Natasja M van Schoor, Nathalie van der Velde, Diana van Heemst, Floor V A van Oort, Sita H Vermeulen, Niek Verweij, Judith M Vonk, Lindsay L Waite, Melanie Waldenberger, Roman Wennauer, Lynne R Wilkens, Christina Willenborg, Tom Wilsgaard, Mary K Wojczynski, Andrew Wong, Alan F Wright, Qunyuan Zhang, Dominique Arveiler, Stephan J L Bakker, John Beilby, Richard N Bergman, Sven Bergmann, Reiner Biffar, John Blangero, Dorret I Boomsma, Stefan R Bornstein, Pascal Bovet, Paolo Brambilla, Morris J Brown, Harry Campbell, Mark J Caulfield, Aravinda Chakravarti, Rory Collins, Francis S Collins, Dana C Crawford, L Adrienne Cupples, John Danesh, Ulf de Faire, Hester M den Ruijter, Raimund Erbel, Jeanette Erdmann, Johan G Eriksson, Martin Farrall, Ele Ferrannini, Jean Ferrières, Ian Ford, Nita G Forouhi, Terrence Forrester, Ron T Gansevoort, Pablo V Gejman, Christian Gieger, Alain Golay, Omri Gottesman, Vilmundur Gudnason, Ulf Gyllensten, David W Haas, Alistair S Hall, Tamara B Harris, Andrew T Hattersley, Andrew C Heath, Christian Hengstenberg, Andrew A Hicks, Lucia A Hindorff, Aroon D Hingorani, Albert Hofman, G Kees Hovingh, Steve E Humphries, Steven C Hunt, Elina Hypponen, Kevin B Jacobs, Marjo-Riitta Jarvelin, Pekka Jousilahti, Antti M Jula, Jaakko Kaprio, John J P Kastelein, Manfred Kayser, Frank Kee, Sirkka M Keinanen-Kiukaanniemi, Lambertus A Kiemeney, Jaspal S Kooner, Charles Kooperberg, Seppo Koskinen, Peter Kovacs, Aldi T Kraja, Meena Kumari, Johanna Kuusisto, Timo A Lakka, Claudia Langenberg, Loic Le Marchand, Terho Lehtimäki, Sara Lupoli, Pamela A F Madden, Satu Männistö, Paolo Manunta, André Marette, Tara C Matise, Barbara McKnight, Thomas Meitinger, Frans L Moll, Grant W Montgomery, Andrew D Morris, Andrew P Morris, Jeffrey C Murray, Mari Nelis, Claes Ohlsson, Albertine J Oldehinkel, Ken K Ong, Willem H Ouwehand, Gerard Pasterkamp, Annette Peters, Peter P Pramstaller, Jackie F Price, Lu Qi, Olli T Raitakari, Tuomo Rankinen, D C Rao, Treva K Rice, Marylyn Ritchie, Igor Rudan, Veikko Salomaa, Nilesh J Samani, Jouko Saramies, Mark A Sarzynski, Peter E H Schwarz, Sylvain Sebert, Peter Sever, Alan R Shuldiner, Juha Sinisalo, Valgerdur Steinthorsdottir, Ronald P Stolk, Jean-Claude Tardif, Anke Tönjes, Angelo Tremblay, Elena Tremoli, Jarmo Virtamo, Marie-Claude Vohl, Philippe Amouyel, Folkert W Asselbergs, Themistocles L Assimes, Murielle Bochud, Bernhard O Boehm, Eric Boerwinkle, Erwin P Bottinger, Claude Bouchard, Stéphane Cauchi, John C Chambers, Stephen J Chanock, Richard S Cooper, Paul I W de Bakker, George Dedoussis, Luigi Ferrucci, Paul W Franks, Philippe Froguel, Leif C Groop, Christopher A Haiman, Anders Hamsten, M Geoffrey Hayes, Jennie Hui, David J Hunter, Kristian Hveem, J Wouter Jukema, Robert C Kaplan, Mika Kivimaki, Diana Kuh, Markku Laakso, Yongmei Liu, Nicholas G Martin, Winfried März, Mads Melbye, Susanne Moebus, Patricia B Munroe, Inger Njølstad, Ben A Oostra, Colin N A Palmer, Nancy L Pedersen, Markus Perola, Louis Pérusse, Ulrike Peters, Joseph E Powell, Chris Power, Thomas Quertermous, Rainer Rauramaa, Eva Reinmaa, Paul M Ridker, Fernando Rivadeneira, Jerome I Rotter, Timo E Saaristo, Danish Saleheen, David Schlessinger, P Eline Slagboom, Harold Snieder, Tim D Spector, Konstantin Strauch, Michael Stumvoll, Jaakko Tuomilehto, Matti Uusitupa, Pim van der Harst, Henry Völzke, Mark Walker, Nicholas J Wareham, Hugh Watkins, H-Erich Wichmann, James F Wilson, Pieter Zanen, Panos Deloukas, Iris M Heid, Cecilia M Lindgren, Karen L Mohlke, Elizabeth K Speliotes, Unnur Thorsteinsdottir, Inês Barroso, Caroline S Fox, Kari E North, David P Strachan, Jacques S Beckmann, Sonja I Berndt, Michael Boehnke, Ingrid B Borecki, Mark I McCarthy, Andres Metspalu, Kari Stefansson, André G Uitterlinden, Cornelia M van Duijn, Lude Franke, Cristen J Willer, Alkes L Price, Guillaume Lettre, Ruth J F Loos, Michael N Weedon, Erik Ingelsson, Jeffrey R O'Connell, Goncalo R Abecasis, Daniel I Chasman, Michael E Goddard, Peter M Visscher, Joel N Hirschhorn & Timothy M Frayling

Publication date: February 2015
Source:Trends in Cell Biology, Volume 25, Issue 2
Author(s): Li-quan Zhou , Jurrien Dean
Despite investigative interest, the artificial derivation of pluripotent stem cells remains inefficient and incomplete reprogramming hinders its potential as a reliable tool in regenerative medicine. By contrast, fusion of terminally differentiated gametes at fertilization activates efficient epigenetic reprogramming to ensure totipotency of early embryos. Understanding the epigenetic mechanisms required for the transition from the fertilized egg to the embryo can improve efforts to reprogram differentiated cells to pluripotent/totipotent cells for therapeutic use. We review recent discoveries that are providing insight into the molecular mechanisms required for epigenetic reprogramming to totipotency in vivo.

Nature Reviews Molecular Cell Biology 15, 749 (2014). doi:10.1038/nrm3884

Authors: William H. Hudson & Eric A. Ortlund

Proteins that bind both DNA and RNA typify the ability of a single gene product to perform multiple functions. Such DNA- and RNA-binding proteins (DRBPs) have unique functional characteristics that stem from their specific structural features; these developed early in evolution and are widely conserved.

Publication date: Available online 16 October 2014
Source:Cell
Author(s): Stephane E. Castel , Jie Ren , Sonali Bhattacharjee , An-Yun Chang , Mar Sánchez , Alberto Valbuena , Francisco Antequera , Robert A. Martienssen
Nuclear RNAi is an important regulator of transcription and epigenetic modification, but the underlying mechanisms remain elusive. Using a genome-wide approach in the fission yeast S. pombe, we have found that Dcr1, but not other components of the canonical RNAi pathway, promotes the release of Pol II from the 3′ end of highly transcribed genes, and, surprisingly, from antisense transcription of rRNA and tRNA genes, which are normally transcribed by Pol I and Pol III. These Dcr1-terminated loci correspond to sites of replication stress and DNA damage, likely resulting from transcription-replication collisions. At the rDNA loci, release of Pol II facilitates DNA replication and prevents homologous recombination, which would otherwise lead to loss of rDNA repeats especially during meiosis. Our results reveal a novel role for Dcr1-mediated transcription termination in genome maintenance and may account for widespread regulation of genome stability by nuclear RNAi in higher eukaryotes.

Graphical abstract

Teaser

Dicer regulates genomic stability by preventing replication stress and DNA damage resulting from transcription-replication collisions. Dicer-mediated release of Pol II during transcription termination facilitates DNA replication and prevents homologous replication.

Publication date: Available online 16 October 2014
Source:Cell
Author(s): Tanweer Hussain , Jose L. Llácer , Israel S. Fernández , Antonio Munoz , Pilar Martin-Marcos , Christos G. Savva , Jon R. Lorsch , Alan G. Hinnebusch , V. Ramakrishnan
During eukaryotic translation initiation, initiator tRNA does not insert fully into the P decoding site on the 40S ribosomal subunit. This conformation (POUT) is compatible with scanning mRNA for the AUG start codon. Base pairing with AUG is thought to promote isomerization to a more stable conformation (PIN) that arrests scanning and promotes dissociation of eIF1 from the 40S subunit. Here, we present a cryoEM reconstruction of a yeast preinitiation complex at 4.0 Å resolution with initiator tRNA in the PIN state, prior to eIF1 release. The structure reveals stabilization of the codon-anticodon duplex by the N-terminal tail of eIF1A, changes in the structure of eIF1 likely instrumental in its subsequent release, and changes in the conformation of eIF2. The mRNA traverses the entire mRNA cleft and makes connections to the regulatory domain of eIF2α, eIF1A, and ribosomal elements that allow recognition of context nucleotides surrounding the AUG codon.

Graphical abstract

Teaser

The cryoEM structure of a partial yeast 48S preinitiation complex at 4.0 Å resolution shows initiator tRNAi in the act of recognizing the start codon prior to eIF1 release. This snapshot of the transition from scanning to codon recognition provides a framework for numerous genetic and biochemical findings underlying the current model for eukaryotic translation initiation.

Global identification of target recognition and cleavage by the Microprocessor in human ES cells.

Nucleic Acids Res. 2014 Oct 17;

Authors: Seong Y, Lim DH, Kim A, Seo JH, Lee YS, Song H, Kwon YS

Abstract
The Microprocessor plays an essential role in canonical miRNA biogenesis by facilitating cleavage of stem-loop structures in primary transcripts to yield pre-miRNAs. Although miRNA biogenesis has been extensively studied through biochemical and molecular genetic approaches, it has yet to be addressed to what extent the current miRNA biogenesis models hold true in intact cells. To address the issues of in vivo recognition and cleavage by the Microprocessor, we investigate RNAs that are associated with DGCR8 and Drosha by using immunoprecipitation coupled with next-generation sequencing. Here, we present global protein-RNA interactions with unprecedented sensitivity and specificity. Our data indicate that precursors of canonical miRNAs and miRNA-like hairpins are the major substrates of the Microprocessor. As a result of specific enrichment of nascent cleavage products, we are able to pinpoint the Microprocessor-mediated cleavage sites per se at single-nucleotide resolution. Unexpectedly, a 2-nt 3' overhang invariably exists at the ends of cleaved bases instead of nascent pre-miRNAs. Besides canonical miRNA precursors, we find that two novel miRNA-like structures embedded in mRNAs are cleaved to yield pre-miRNA-like hairpins, uncoupled from miRNA maturation. Our data provide a framework for in vivo Microprocessor-mediated cleavage and a foundation for experimental and computational studies on miRNA biogenesis in living cells.

PMID: 25326327 [PubMed - as supplied by publisher]

Publication date: November 2014
Source:Trends in Biotechnology, Volume 32, Issue 11
Author(s): Marco F. Schmidt
miRNAs, short ribonucleic acid gene regulators, are increasingly popular drug targets. Traditionally ‘undruggable’ proteins can be targeted via their miRNA gene regulators, enabling the treatment of diseases that, at present, seem impossible to cure. However, addressing miRNAs requires innovation at the level of drug discovery. This review article outlines the potential of miRNAs as drug targets, focuses on the challenges of developing miRNA-targeting drugs, and surveys new advances. The aim is to provide an orientation guide for scientists, as well business analysts, to help them navigate the jungle of different approaches in miRNA drug discovery.