BLM helicase facilitates RNA polymerase I-mediated ribosomal RNA transcription.

PubMed

Grierson, Patrick M; Lillard, Kate; Behbehani, Gregory K; Combs, Kelly A; Bhattacharyya, Saumitri; Acharya, Samir; Groden, Joanna

2012-03-01

Bloom's syndrome (BS) is an autosomal recessive disorder that is invariably characterized by severe growth retardation and cancer predisposition. The Bloom's syndrome helicase (BLM), mutations of which lead to BS, localizes to promyelocytic leukemia protein bodies and to the nucleolus of the cell, the site of RNA polymerase I-mediated ribosomal RNA (rRNA) transcription. rRNA transcription is fundamental for ribosome biogenesis and therefore protein synthesis, cellular growth and proliferation; its inhibition limits cellular growth and proliferation as well as bodily growth. We report that nucleolar BLM facilitates RNA polymerase I-mediated rRNA transcription. Immunofluorescence studies demonstrate the dependance of BLM nucleolar localization upon ongoing RNA polymerase I-mediated rRNA transcription. In vivo protein co-immunoprecipitation demonstrates that BLM interacts with RPA194, a subunit of RNA polymerase I. (3)H-uridine pulse-chase assays demonstrate that BLM expression is required for efficient rRNA transcription. In vitro helicase assays demonstrate that BLM unwinds GC-rich rDNA-like substrates that form in the nucleolus and normally inhibit progression of the RNA polymerase I transcription complex. These studies suggest that nucleolar BLM modulates rDNA structures in association with RNA polymerase I to facilitate RNA polymerase I-mediated rRNA transcription. Given the intricate relationship between rDNA metabolism and growth, our data may help in understanding the etiology of proportional dwarfism in BS.

saRNA-guided Ago2 targets the RITA complex to promoters to stimulate transcription.

PubMed

Portnoy, Victoria; Lin, Szu Hua Sharon; Li, Kathy H; Burlingame, Alma; Hu, Zheng-Hui; Li, Hao; Li, Long-Cheng

2016-03-01

Small activating RNAs (saRNAs) targeting specific promoter regions are able to stimulate gene expression at the transcriptional level, a phenomenon known as RNA activation (RNAa). It is known that RNAa depends on Ago2 and is associated with epigenetic changes at the target promoters. However, the precise molecular mechanism of RNAa remains elusive. Using human CDKN1A (p21) as a model gene, we characterized the molecular nature of RNAa. We show that saRNAs guide Ago2 to and associate with target promoters. saRNA-loaded Ago2 facilitates the assembly of an RNA-induced transcriptional activation (RITA) complex, which, in addition to saRNA-Ago2 complex, includes RHA and CTR9, the latter being a component of the PAF1 complex. RITA interacts with RNA polymerase II to stimulate transcription initiation and productive elongation, accompanied by monoubiquitination of histone 2B. Our results establish the existence of a cellular RNA-guided genome-targeting and transcriptional activation mechanism and provide important new mechanistic insights into the RNAa process.

Brain tumor is a sequence-specific RNA-binding protein that directs maternal mRNA clearance during the Drosophila maternal-to-zygotic transition.

PubMed

Laver, John D; Li, Xiao; Ray, Debashish; Cook, Kate B; Hahn, Noah A; Nabeel-Shah, Syed; Kekis, Mariana; Luo, Hua; Marsolais, Alexander J; Fung, Karen Yy; Hughes, Timothy R; Westwood, J Timothy; Sidhu, Sachdev S; Morris, Quaid; Lipshitz, Howard D; Smibert, Craig A

2015-05-12

Brain tumor (BRAT) is a Drosophila member of the TRIM-NHL protein family. This family is conserved among metazoans and its members function as post-transcriptional regulators. BRAT was thought to be recruited to mRNAs indirectly through interaction with the RNA-binding protein Pumilio (PUM). However, it has recently been demonstrated that BRAT directly binds to RNA. The precise sequence recognized by BRAT, the extent of BRAT-mediated regulation, and the exact roles of PUM and BRAT in post-transcriptional regulation are unknown. Genome-wide identification of transcripts associated with BRAT or with PUM in Drosophila embryos shows that they bind largely non-overlapping sets of mRNAs. BRAT binds mRNAs that encode proteins associated with a variety of functions, many of which are distinct from those implemented by PUM-associated transcripts. Computational analysis of in vitro and in vivo data identified a novel RNA motif recognized by BRAT that confers BRAT-mediated regulation in tissue culture cells. The regulatory status of BRAT-associated mRNAs suggests a prominent role for BRAT in post-transcriptional regulation, including a previously unidentified role in transcript degradation. Transcriptomic analysis of embryos lacking functional BRAT reveals an important role in mediating the decay of hundreds of maternal mRNAs during the maternal-to-zygotic transition. Our results represent the first genome-wide analysis of the mRNAs associated with a TRIM-NHL protein and the first identification of an RNA motif bound by this protein family. BRAT is a prominent post-transcriptional regulator in the early embryo through mechanisms that are largely independent of PUM.

Kaposi's Sarcoma-Associated Herpesvirus Hijacks RNA Polymerase II To Create a Viral Transcriptional Factory

PubMed Central

Chen, Christopher Phillip; Lyu, Yuanzhi; Chuang, Frank; Nakano, Kazushi; Izumiya, Chie; Jin, Di; Campbell, Mel

2017-01-01

ABSTRACT Locally concentrated nuclear factors ensure efficient binding to DNA templates, facilitating RNA polymerase II recruitment and frequent reutilization of stable preinitiation complexes. We have uncovered a mechanism for effective viral transcription by focal assembly of RNA polymerase II around Kaposi's sarcoma-associated herpesvirus (KSHV) genomes in the host cell nucleus. Using immunofluorescence labeling of latent nuclear antigen (LANA) protein, together with fluorescence in situ RNA hybridization (RNA-FISH) of the intron region of immediate early transcripts, we visualized active transcription of viral genomes in naturally infected cells. At the single-cell level, we found that not all episomes were uniformly transcribed following reactivation stimuli. However, those episomes that were being transcribed would spontaneously aggregate to form transcriptional “factories,” which recruited a significant fraction of cellular RNA polymerase II. Focal assembly of “viral transcriptional factories” decreased the pool of cellular RNA polymerase II available for cellular gene transcription, which consequently impaired cellular gene expression globally, with the exception of selected ones. The viral transcriptional factories localized with replicating viral genomic DNAs. The observed colocalization of viral transcriptional factories with replicating viral genomic DNA suggests that KSHV assembles an “all-in-one” factory for both gene transcription and DNA replication. We propose that the assembly of RNA polymerase II around viral episomes in the nucleus may be a previously unexplored aspect of KSHV gene regulation by confiscation of a limited supply of RNA polymerase II in infected cells. IMPORTANCE B cells infected with Kaposi's sarcoma-associated herpesvirus (KSHV) harbor multiple copies of the KSHV genome in the form of episomes. Three-dimensional imaging of viral gene expression in the nucleus allows us to study interactions and changes in the physical distribution of these episomes following stimulation. The results showed heterogeneity in the responses of individual KSHV episomes to stimuli within a single reactivating cell; those episomes that did respond to stimulation, aggregated within large domains that appear to function as viral transcription factories. A significant portion of cellular RNA polymerase II was trapped in these factories and served to transcribe viral genomes, which coincided with an overall decrease in cellular gene expression. Our findings uncover a strategy of KSHV gene regulation through focal assembly of KSHV episomes and a molecular mechanism of late gene expression. PMID:28331082

Purification of Transcript-Specific mRNP Complexes Formed In Vivo from Saccharomyces cerevisiae.

PubMed

Smith, Jenna E; Baker, Kristian E

2017-01-01

RNA binding proteins play critical roles in shaping the complex life cycle of cellular transcripts. For most RNAs, the association with a distinct complement of proteins serves to orchestrate its unique pattern of maturation, localization, translation, and stability. A key aspect to understanding how transcripts are differentially regulated lies, therefore, in the ability to identify the particular repertoire of protein binding partners associated with an individual transcript. We describe here an optimized experimental procedure for purifying a single mRNA population from yeast cells for the characterization of transcript-specific mRNA-protein complexes (mRNPs) as they exist in vivo. Chemical cross-linking is used to trap native mRNPs and facilitate the co-purification of protein complexes associated with an individual transcript population that is captured under stringent conditions from cell lysates through hybridization to complementary DNA oligonucleotides. The resulting mRNP is highly enriched and largely devoid of non-target transcripts, and can be used for a number of downstream analyses including protein identification by mass spectrometry.

Factor requirements for transcription in the Archaeon Sulfolobus shibatae.

PubMed

Qureshi, S A; Bell, S D; Jackson, S P

1997-05-15

Archaea (archaebacteria) constitute a domain of life that is distinct from Bacteria (eubacteria) and Eucarya (eukaryotes). Although archaeal cells share many morphological features with eubacteria, their transcriptional apparatus is more akin to eukaryotic RNA polymerases I, II and III than it is to eubacterial transcription systems. Thus, in addition to possessing a 10 subunit RNA polymerase and a homologue of the TATA-binding protein (TBP), Archaea possess a polypeptide termed TFB that is homologous to eukaryotic TFIIB. Here, we investigate the factor requirements for transcription of several promoters of the archaeon Sulfolobus shibatae and its associated virus SSV. Through in vitro transcription and immunodepletion, we demonstrate that S. shibatae TBP, TFB and RNA polymerase are not complexed tightly with one another and that each is required for efficient transcription of all promoters tested. Furthermore, full transcription is restored by supplementing respective depleted extracts with recombinant TBP or TFB, indicating that TBP-associated factors or TFB-associated factors are not required. Indeed, gel-filtration suggests that Sulfolobus TBP and TFB are not associated stably with other proteins. Finally, all promoters analysed are transcribed accurately and efficiently in an in vitro system comprising recombinant TBP and TFB, together with essentially homogeneous preparation of RNA polymerase. Transcription in Archaea is therefore fundamentally homologous to that in eukaryotes, although factor requirements appear to be much less complex.

The yeast transcription elongation factor Spt4/5 is a sequence‐specific RNA binding protein

PubMed Central

Blythe, Amanda J.; Yazar‐Klosinski, Berra; Webster, Michael W.; Chen, Eefei; Vandevenne, Marylène; Bendak, Katerina; Mackay, Joel P.; Hartzog, Grant A.

2016-01-01

Abstract The heterodimeric transcription elongation factor Spt4/Spt5 (Spt4/5) tightly associates with RNAPII to regulate both transcriptional elongation and co‐transcriptional pre‐mRNA processing; however, the mechanisms by which Spt4/5 acts are poorly understood. Recent studies of the human and Drosophila Spt4/5 complexes indicate that they can bind nucleic acids in vitro. We demonstrate here that yeast Spt4/5 can bind in a sequence‐specific manner to single stranded RNA containing AAN repeats. Furthermore, we show that the major protein determinants for RNA‐binding are Spt4 together with the NGN domain of Spt5 and that the KOW domains are not required for RNA recognition. These findings attribute a new function to a domain of Spt4/5 that associates directly with RNAPII, making significant steps towards elucidating the mechanism behind transcriptional control by Spt4/5. PMID:27376968

RNA G-quadruplexes: emerging mechanisms in disease

PubMed Central

Cammas, Anne

2017-01-01

Abstract RNA G-quadruplexes (G4s) are formed by G-rich RNA sequences in protein-coding (mRNA) and non-coding (ncRNA) transcripts that fold into a four-stranded conformation. Experimental studies and bioinformatic predictions support the view that these structures are involved in different cellular functions associated to both DNA processes (telomere elongation, recombination and transcription) and RNA post-transcriptional mechanisms (including pre-mRNA processing, mRNA turnover, targeting and translation). An increasing number of different diseases have been associated with the inappropriate regulation of RNA G4s exemplifying the potential importance of these structures on human health. Here, we review the different molecular mechanisms underlying the link between RNA G4s and human diseases by proposing several overlapping models of deregulation emerging from recent research, including (i) sequestration of RNA-binding proteins, (ii) aberrant expression or localization of RNA G4-binding proteins, (iii) repeat associated non-AUG (RAN) translation, (iv) mRNA translational blockade and (v) disabling of protein–RNA G4 complexes. This review also provides a comprehensive survey of the functional RNA G4 and their mechanisms of action. Finally, we highlight future directions for research aimed at improving our understanding on RNA G4-mediated regulatory mechanisms linked to diseases. PMID:28013268

Interdependence between transcription and mRNP processing and export, and its impact on genetic stability.

PubMed

Luna, Rosa; Jimeno, Sonia; Marín, Mercedes; Huertas, Pablo; García-Rubio, María; Aguilera, Andrés

2005-06-10

The conserved eukaryotic THO-TREX complex acts at the interface between transcription and mRNA export and affects transcription-associated recombination. To investigate the interdependence of nuclear mRNA processes and their impact on genomic integrity, we analyzed transcript accumulation and recombination of 40 selected mutants covering representative steps of the biogenesis and export of the messenger ribonucleoprotein particle (mRNP). None of the mutants analyzed shared the strong transcript-accumulation defect and hyperrecombination of THO mutants. Nevertheless, mutants in 3' end cleavage/polyadenylation, nuclear exosome, and mRNA export showed a weak but significant effect on recombination and transcript accumulation. Mutants of the nuclear exosome (rrp6) and 3' end processing factors (rna14 and rna15) showed inefficient transcription elongation and genetic interactions with THO. The results suggest a tight interdependence among mRNP biogenesis steps and transcription and an unexpected effect of the nuclear exosome and the cleavage/polyadenylation factors on transcription elongation and genetic integrity.

TGF-β Suppression of HBV RNA through AID-Dependent Recruitment of an RNA Exosome Complex

PubMed Central

Kitamura, Kouichi; Wang, Zhe; Chowdhury, Sajeda; Monjurul, Ahasan Md; Wakae, Kousho; Koura, Miki; Shimadu, Miyuki; Kinoshita, Kazuo; Muramatsu, Masamichi

2015-01-01

Transforming growth factor (TGF)-β inhibits hepatitis B virus (HBV) replication although the intracellular effectors involved are not determined. Here, we report that reduction of HBV transcripts by TGF-β is dependent on AID expression, which significantly decreases both HBV transcripts and viral DNA, resulting in inhibition of viral replication. Immunoprecipitation reveals that AID physically associates with viral P protein that binds to specific virus RNA sequence called epsilon. AID also binds to an RNA degradation complex (RNA exosome proteins), indicating that AID, RNA exosome, and P protein form an RNP complex. Suppression of HBV transcripts by TGF-β was abrogated by depletion of either AID or RNA exosome components, suggesting that AID and the RNA exosome involve in TGF-β mediated suppression of HBV RNA. Moreover, AID-mediated HBV reduction does not occur when P protein is disrupted or when viral transcription is inhibited. These results suggest that induced expression of AID by TGF-β causes recruitment of the RNA exosome to viral RNP complex and the RNA exosome degrades HBV RNA in a transcription-coupled manner. PMID:25836330

Spt6 Association with RNA Polymerase II Directs mRNA Turnover During Transcription.

PubMed

Dronamraju, Raghuvar; Hepperla, Austin J; Shibata, Yoichiro; Adams, Alexander T; Magnuson, Terry; Davis, Ian J; Strahl, Brian D

2018-06-21

Spt6 is an essential histone chaperone that mediates nucleosome reassembly during gene transcription. Spt6 also associates with RNA polymerase II (RNAPII) via a tandem Src2 homology domain. However, the significance of Spt6-RNAPII interaction is not well understood. Here, we show that Spt6 recruitment to genes and the nucleosome reassembly functions of Spt6 can still occur in the absence of its association with RNAPII. Surprisingly, we found that Spt6-RNAPII association is required for efficient recruitment of the Ccr4-Not de-adenylation complex to transcribed genes for essential degradation of a range of mRNAs, including mRNAs required for cell-cycle progression. These findings reveal an unexpected control mechanism for mRNA turnover during transcription facilitated by a histone chaperone. Copyright © 2018 Elsevier Inc. All rights reserved.

Mod5 protein binds to tRNA gene complexes and affects local transcriptional silencing

PubMed Central

Pratt-Hyatt, Matthew; Pai, Dave A.; Haeusler, Rebecca A.; Wozniak, Glenn G.; Good, Paul D.; Miller, Erin L.; McLeod, Ian X.; Yates, John R.; Hopper, Anita K.; Engelke, David R.

2013-01-01

The tRNA gene-mediated (tgm) silencing of RNA polymerase II promoters is dependent on subnuclear clustering of the tRNA genes, but genetic analysis shows that the silencing requires additional mechanisms. We have identified proteins that bind tRNA gene transcription complexes and are required for tgm silencing but not required for gene clustering. One of the proteins, Mod5, is a tRNA modifying enzyme that adds an N6-isopentenyl adenosine modification at position 37 on a small number of tRNAs in the cytoplasm, although a subpopulation of Mod5 is also found in the nucleus. Recent publications have also shown that Mod5 has tumor suppressor characteristics in humans as well as confers drug resistance through prion-like misfolding in yeast. Here, we show that a subpopulation of Mod5 associates with tRNA gene complexes in the nucleolus. This association occurs and is required for tgm silencing regardless of whether the pre-tRNA transcripts are substrates for Mod5 modification. In addition, Mod5 is bound to nuclear pre-tRNA transcripts, although they are not substrates for the A37 modification. Lastly, we show that truncation of the tRNA transcript to remove the normal tRNA structure also alleviates silencing, suggesting that synthesis of intact pre-tRNAs is required for the silencing mechanism. These results are discussed in light of recent results showing that silencing near tRNA genes also requires chromatin modification. PMID:23898186

Widespread promoter-mediated coordination of transcription and mRNA degradation

PubMed Central

2012-01-01

Background Previous work showed that mRNA degradation is coordinated with transcription in yeast, and in several genes the control of mRNA degradation was linked to promoter elements through two different mechanisms. Here we show at the genomic scale that the coordination of transcription and mRNA degradation is promoter-dependent in yeast and is also observed in humans. Results We first demonstrate that swapping upstream cis-regulatory sequences between two yeast species affects both transcription and mRNA degradation and suggest that while some cis-regulatory elements control either transcription or degradation, multiple other elements enhance both processes. Second, we show that adjacent yeast genes that share a promoter (through divergent orientation) have increased similarity in their patterns of mRNA degradation, providing independent evidence for the promoter-mediated coupling of transcription to mRNA degradation. Finally, analysis of the differences in mRNA degradation rates between mammalian cell types or mammalian species suggests a similar coordination between transcription and mRNA degradation in humans. Conclusions Our results extend previous studies and suggest a pervasive promoter-mediated coordination between transcription and mRNA degradation in yeast. The diverse genes and regulatory elements associated with this coordination suggest that it is generated by a global mechanism of gene regulation and modulated by gene-specific mechanisms. The observation of a similar coupling in mammals raises the possibility that coupling of transcription and mRNA degradation may reflect an evolutionarily conserved phenomenon in gene regulation. PMID:23237624

Myb-binding protein 1a (Mybbp1a) regulates levels and processing of pre-ribosomal RNA.

PubMed

Hochstatter, Julia; Hölzel, Michael; Rohrmoser, Michaela; Schermelleh, Lothar; Leonhardt, Heinrich; Keough, Rebecca; Gonda, Thomas J; Imhof, Axel; Eick, Dirk; Längst, Gernot; Németh, Attila

2012-07-13

Ribosomal RNA gene transcription, co-transcriptional processing, and ribosome biogenesis are highly coordinated processes that are tightly regulated during cell growth. In this study we discovered that Mybbp1a is associated with both the RNA polymerase I complex and the ribosome biogenesis machinery. Using a reporter assay that uncouples transcription and RNA processing, we show that Mybbp1a represses rRNA gene transcription. In addition, overexpression of the protein reduces RNA polymerase I loading on endogenous rRNA genes as revealed by chromatin immunoprecipitation experiments. Accordingly, depletion of Mybbp1a results in an accumulation of the rRNA precursor in vivo but surprisingly also causes growth arrest of the cells. This effect can be explained by the observation that the modulation of Mybbp1a protein levels results in defects in pre-rRNA processing within the cell. Therefore, the protein may play a dual role in the rRNA metabolism, potentially linking and coordinating ribosomal DNA transcription and pre-rRNA processing to allow for the efficient synthesis of ribosomes.

Epidrug mediated re-expression of miRNA targeting the HMGA transcripts in pituitary cells.

PubMed

Kitchen, Mark O; Yacqub-Usman, Kiren; Emes, Richard D; Richardson, Alan; Clayton, Richard N; Farrell, William E

2015-10-01

Transgenic mice overexpressing the high mobility group A (HMGA) genes, Hmga1 or Hmga2 develop pituitary tumours and their overexpression is also a frequent finding in human pituitary adenomas. In some cases, increased expression of HMGA2 but not that of HMGA1 is consequent to genetic perturbations. However, recent studies show that down-regulation of microRNA (miRNA), that contemporaneously target the HMGA1 and HMGA2 transcripts, are associated with their overexpression. In a cohort of primary pituitary adenoma we determine the impact of epigenetic modifications on the expression of HMGA-targeting miRNA. For these miRNAs, chromatin immunoprecipitations showed that transcript down-regulation is correlated with histone tail modifications associated with condensed silenced genes. The functional impact of epigenetic modification on miRNA expression was determined in the rodent pituitary cell line, GH3. In these cells, histone tail, miRNA-associated, modifications were similar to those apparent in human adenoma and likely account for their repression. Indeed, challenge of GH3 cells with the epidrugs, zebularine and TSA, led to enrichment of the histone modification, H3K9Ac, associated with active genes, and depletion of the modification, H3K27me3, associated with silent genes and re-expression of HMGA-targeting miRNA. Moreover, epidrugs challenges were also associated with a concomitant decrease in hmga1 transcript and protein levels and concurrent increase in bmp-4 expression. These findings show that the inverse relationship between HMGA expression and targeting miRNA is reversible through epidrug interventions. In addition to showing a mechanistic link between epigenetic modifications and miRNA expression these findings underscore their potential as therapeutic targets in this and other diseases.

RNA polymerase activity is associated with viral particles isolated from Leishmania braziliensis subsp. guyanensis.

PubMed Central

Widmer, G; Keenan, M C; Patterson, J L

1990-01-01

Viral particles purified from species of the protozoan parasite Leishmania braziliensis subsp. guyanensis by centrifugation in CsCl gradients were examined for the presence of viral polymerase. We demonstrated that RNA-dependent RNA polymerase is associated with viral particles. Viral transcription was studied in vitro with pulse-chase experiments and by assaying the RNase sensitivity of the viral transcripts. Viral polymerase synthesized full-length transcripts within 1 h. Double-strained, genome-length, and single-stranded RNAs were produced in this system. The nature of the RNA extracted from virions was also tested by RNase protection assays; both single-stranded and double-stranded RNAs were found. Images PMID:2370680

Molecular evidence that the eukaryotic THO/TREX complex is required for efficient transcription elongation.

PubMed

Rondón, Ana G; Jimeno, Sonia; García-Rubio, María; Aguilera, Andrés

2003-10-03

THO/TREX is a conserved eukaryotic complex formed by the core THO complex plus proteins involved in mRNA metabolism and export such as Sub2 and Yra1. Mutations in any of the THO/TREX structural genes cause pleiotropic phenotypes such as transcription impairment, increased transcription-associated recombination, and mRNA export defects. To assay the relevance of THO/TREX complex in transcription, we performed in vitro transcription elongation assays in mutant cell extracts using supercoiled DNA templates containing two G-less cassettes. With these assays, we demonstrate that hpr1delta, tho2delta, and mft1delta mutants of the THO complex and sub2 mutants show significant reductions in the efficiency of transcription elongation. The mRNA expression defect of hpr1delta mutants was not due to an increase in mRNA decay, as determined by mRNA half-life measurements and mRNA time course accumulation experiments in the absence of Rrp6p exoribonuclease. This work demonstrates that THO and Sub2 are required for efficient transcription elongation, providing further evidence for the coupling between transcription and mRNA metabolism and export.

A novel TBP-TAF complex on RNA polymerase II-transcribed snRNA genes.

PubMed

Zaborowska, Justyna; Taylor, Alice; Roeder, Robert G; Murphy, Shona

2012-01-01

Initiation of transcription of most human genes transcribed by RNA polymerase II (RNAP II) requires the formation of a preinitiation complex comprising TFIIA, B, D, E, F, H and RNAP II. The general transcription factor TFIID is composed of the TATA-binding protein and up to 13 TBP-associated factors. During transcription of snRNA genes, RNAP II does not appear to make the transition to long-range productive elongation, as happens during transcription of protein-coding genes. In addition, recognition of the snRNA gene-type specific 3' box RNA processing element requires initiation from an snRNA gene promoter. These characteristics may, at least in part, be driven by factors recruited to the promoter. For example, differences in the complement of TAFs might result in differential recruitment of elongation and RNA processing factors. As precedent, it already has been shown that the promoters of some protein-coding genes do not recruit all the TAFs found in TFIID. Although TAF5 has been shown to be associated with RNAP II-transcribed snRNA genes, the full complement of TAFs associated with these genes has remained unclear. Here we show, using a ChIP and siRNA-mediated approach, that the TBP/TAF complex on snRNA genes differs from that found on protein-coding genes. Interestingly, the largest TAF, TAF1, and the core TAFs, TAF10 and TAF4, are not detected on snRNA genes. We propose that this snRNA gene-specific TAF subset plays a key role in gene type-specific control of expression.

Fail-safe transcription termination: Because one is never enough.

PubMed

Lemay, Jean-François; Bachand, François

2015-01-01

Termination of RNA polymerase II (RNAPII) transcription is a fundamental step of gene expression that involves the release of the nascent transcript and dissociation of RNAPII from the DNA template. As transcription termination is intimately linked to RNA 3' end processing, termination pathways have a key decisive influence on the fate of the transcribed RNA. Quite remarkably, when reaching the 3' end of genes, a substantial fraction of RNAPII fail to terminate transcription, requiring the contribution of alternative or "fail-safe" mechanisms of termination to release the polymerase. This point of view covers redundant mechanisms of transcription termination and how they relate to conventional termination models. In particular, we expand on recent findings that propose a reverse torpedo model of termination, in which the 3'5' exonucleolytic activity of the RNA exosome targets transcription events associated with paused and backtracked RNAPII.

A Conserved Nuclear Cyclophilin Is Required for Both RNA Polymerase II Elongation and Co-transcriptional Splicing in Caenorhabditis elegans

PubMed Central

Ahn, Jeong H.; Rechsteiner, Andreas; Strome, Susan; Kelly, William G.

2016-01-01

The elongation phase of transcription by RNA Polymerase II (Pol II) involves numerous events that are tightly coordinated, including RNA processing, histone modification, and chromatin remodeling. RNA splicing factors are associated with elongating Pol II, and the interdependent coupling of splicing and elongation has been documented in several systems. Here we identify a conserved, multi-domain cyclophilin family member, SIG-7, as an essential factor for both normal transcription elongation and co-transcriptional splicing. In embryos depleted for SIG-7, RNA levels for over a thousand zygotically expressed genes are substantially reduced, Pol II becomes significantly reduced at the 3’ end of genes, marks of transcription elongation are reduced, and unspliced mRNAs accumulate. Our findings suggest that SIG-7 plays a central role in both Pol II elongation and co-transcriptional splicing and may provide an important link for their coordination and regulation. PMID:27541139

Posttranscriptional Control of Photosynthetic mRNA Decay under Stress Conditions Requires 3′ and 5′ Untranslated Regions and Correlates with Differential Polysome Association in Rice1[W][OA

PubMed Central

Park, Su-Hyun; Chung, Pil Joong; Juntawong, Piyada; Bailey-Serres, Julia; Kim, Youn Shic; Jung, Harin; Bang, Seung Woon; Kim, Yeon-Ki; Do Choi, Yang; Kim, Ju-Kon

2012-01-01

Abiotic stress, including drought, salinity, and temperature extremes, regulates gene expression at the transcriptional and posttranscriptional levels. Expression profiling of total messenger RNAs (mRNAs) from rice (Oryza sativa) leaves grown under stress conditions revealed that the transcript levels of photosynthetic genes are reduced more rapidly than others, a phenomenon referred to as stress-induced mRNA decay (SMD). By comparing RNA polymerase II engagement with the steady-state mRNA level, we show here that SMD is a posttranscriptional event. The SMD of photosynthetic genes was further verified by measuring the half-lives of the small subunit of Rubisco (RbcS1) and Chlorophyll a/b-Binding Protein1 (Cab1) mRNAs during stress conditions in the presence of the transcription inhibitor cordycepin. To discern any correlation between SMD and the process of translation, changes in total and polysome-associated mRNA levels after stress were measured. Total and polysome-associated mRNA levels of two photosynthetic (RbcS1 and Cab1) and two stress-inducible (Dehydration Stress-Inducible Protein1 and Salt-Induced Protein) genes were found to be markedly similar. This demonstrated the importance of polysome association for transcript stability under stress conditions. Microarray experiments performed on total and polysomal mRNAs indicate that approximately half of all mRNAs that undergo SMD remain polysome associated during stress treatments. To delineate the functional determinant(s) of mRNAs responsible for SMD, the RbcS1 and Cab1 transcripts were dissected into several components. The expressions of different combinations of the mRNA components were analyzed under stress conditions, revealing that both 3′ and 5′ untranslated regions are necessary for SMD. Our results, therefore, suggest that the posttranscriptional control of photosynthetic mRNA decay under stress conditions requires both 3′ and 5′ untranslated regions and correlates with differential polysome association. PMID:22566494

Transcriptional, post-transcriptional and chromatin-associated regulation of pri-miRNAs, pre-miRNAs and moRNAs

PubMed Central

Nepal, Chirag; Coolen, Marion; Hadzhiev, Yavor; Cussigh, Delphine; Mydel, Piotr; Steen, Vidar M.; Carninci, Piero; Andersen, Jesper B.; Bally-Cuif, Laure; Müller, Ferenc; Lenhard, Boris

2016-01-01

MicroRNAs (miRNAs) play a major role in the post-transcriptional regulation of target genes, especially in development and differentiation. Our understanding about the transcriptional regulation of miRNA genes is limited by inadequate annotation of primary miRNA (pri-miRNA) transcripts. Here, we used CAGE-seq and RNA-seq to provide genome-wide identification of the pri-miRNA core promoter repertoire and its dynamic usage during zebrafish embryogenesis. We assigned pri-miRNA promoters to 152 precursor-miRNAs (pre-miRNAs), the majority of which were supported by promoter associated post-translational histone modifications (H3K4me3, H2A.Z) and RNA polymerase II (RNAPII) occupancy. We validated seven miR-9 pri-miRNAs by in situ hybridization and showed similar expression patterns as mature miR-9. In addition, processing of an alternative intronic promoter of miR-9–5 was validated by 5′ RACE PCR. Developmental profiling revealed a subset of pri-miRNAs that are maternally inherited. Moreover, we show that promoter-associated H3K4me3, H2A.Z and RNAPII marks are not only present at pri-miRNA promoters but are also specifically enriched at pre-miRNAs, suggesting chromatin level regulation of pre-miRNAs. Furthermore, we demonstrated that CAGE-seq also detects 3′-end processing of pre-miRNAs on Drosha cleavage site that correlates with miRNA-offset RNAs (moRNAs) production and provides a new tool for detecting Drosha processing events and predicting pre-miRNA processing by a genome-wide assay. PMID:26673698

Accumulation of unstable promoter-associated transcripts upon loss of the nuclear exosome subunit Rrp6p in Saccharomyces cerevisiae

PubMed Central

Davis, Carrie Anne; Ares, Manuel

2006-01-01

Mutations in RRP6 result in the accumulation of aberrant polyadenylated transcripts from small nucleolar RNA genes. We exploited this observation to search for novel noncoding RNA genes in the yeast genome. When RNA from rrp6Δ yeast is compared with wild-type on whole-genome microarrays, numerous intergenic loci exhibit an increased mutant/wild type signal ratio. Among these loci, we found one encoding a new C/D box small nucleolar RNA, as well as a surprising number that gave rise to heterogeneous Trf4p-polyadenylated RNAs with lengths of ≈250–500 nt. This class of RNAs is not easily detected in wild-type cells and appears associated with promoters. Fine mapping of several such transcripts shows they originate near known promoter elements but do not usually extend far enough to act as mRNAs, and may regulate the transcription of downstream mRNAs. Rather than being uninformative transcriptional “noise,” we hypothesize that these transcripts reflect important features of RNA polymerase activity at the promoter. This activity is normally undetectable in wild-type cells because the transcripts are somehow distinguished from true mRNAs and are degraded in an Rrp6p-dependent fashion in the nucleus. PMID:16484372

Growth-dependent regulation of rRNA synthesis is mediated by a transcription initiation factor (TIF-IA).

PubMed

Buttgereit, D; Pflugfelder, G; Grummt, I

1985-11-25

Mouse RNA polymerase I requires at least two chromatographically distinct transcription factors (designated TIF-IA and TIF-IB) to initiate transcription accurately and efficiently in vitro. In this paper we describe the partial purification of TIF-IA by a four-step fractionation procedure. The amount or activity of TIF-IA fluctuates in response to the physiological state of the cells. Extracts from quiescent cells are incapable of specific transcription and do not contain detectable levels of TIF-IA. Transcriptionally inactive extracts can be restored by the addition of TIF-IA preparations that have been highly purified from exponentially growing cells. During the fractionating procedure TIF-IA co-purifies with RNA polymerase I, suggesting that it is functionally associated with the transcribing enzyme. We suggest that only those enzyme molecules that are associated with TIF-IA are capable to interact with TIF-IB and to initiate transcription.

Two familial ALS proteins function in prevention/repair of transcription-associated DNA damage.

PubMed

Hill, Sarah J; Mordes, Daniel A; Cameron, Lisa A; Neuberg, Donna S; Landini, Serena; Eggan, Kevin; Livingston, David M

2016-11-29

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron dysfunction disease that leads to paralysis and death. There is currently no established molecular pathogenesis pathway. Multiple proteins involved in RNA processing are linked to ALS, including FUS and TDP43, and we propose a disease mechanism in which loss of function of at least one of these proteins leads to an accumulation of transcription-associated DNA damage contributing to motor neuron cell death and progressive neurological symptoms. In support of this hypothesis, we find that FUS or TDP43 depletion leads to increased sensitivity to a transcription-arresting agent due to increased DNA damage. Thus, these proteins normally contribute to the prevention or repair of transcription-associated DNA damage. In addition, both FUS and TDP43 colocalize with active RNA polymerase II at sites of DNA damage along with the DNA damage repair protein, BRCA1, and FUS and TDP43 participate in the prevention or repair of R loop-associated DNA damage, a manifestation of aberrant transcription and/or RNA processing. Gaining a better understanding of the role(s) that FUS and TDP43 play in transcription-associated DNA damage could shed light on the mechanisms underlying ALS pathogenesis.

Two familial ALS proteins function in prevention/repair of transcription-associated DNA damage

PubMed Central

Hill, Sarah J.; Mordes, Daniel A.; Cameron, Lisa A.; Neuberg, Donna S.; Landini, Serena; Eggan, Kevin; Livingston, David M.

2016-01-01

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron dysfunction disease that leads to paralysis and death. There is currently no established molecular pathogenesis pathway. Multiple proteins involved in RNA processing are linked to ALS, including FUS and TDP43, and we propose a disease mechanism in which loss of function of at least one of these proteins leads to an accumulation of transcription-associated DNA damage contributing to motor neuron cell death and progressive neurological symptoms. In support of this hypothesis, we find that FUS or TDP43 depletion leads to increased sensitivity to a transcription-arresting agent due to increased DNA damage. Thus, these proteins normally contribute to the prevention or repair of transcription-associated DNA damage. In addition, both FUS and TDP43 colocalize with active RNA polymerase II at sites of DNA damage along with the DNA damage repair protein, BRCA1, and FUS and TDP43 participate in the prevention or repair of R loop-associated DNA damage, a manifestation of aberrant transcription and/or RNA processing. Gaining a better understanding of the role(s) that FUS and TDP43 play in transcription-associated DNA damage could shed light on the mechanisms underlying ALS pathogenesis. PMID:27849576

Revealing stable processing products from ribosome-associated small RNAs by deep-sequencing data analysis.

PubMed

Zywicki, Marek; Bakowska-Zywicka, Kamilla; Polacek, Norbert

2012-05-01

The exploration of the non-protein-coding RNA (ncRNA) transcriptome is currently focused on profiling of microRNA expression and detection of novel ncRNA transcription units. However, recent studies suggest that RNA processing can be a multi-layer process leading to the generation of ncRNAs of diverse functions from a single primary transcript. Up to date no methodology has been presented to distinguish stable functional RNA species from rapidly degraded side products of nucleases. Thus the correct assessment of widespread RNA processing events is one of the major obstacles in transcriptome research. Here, we present a novel automated computational pipeline, named APART, providing a complete workflow for the reliable detection of RNA processing products from next-generation-sequencing data. The major features include efficient handling of non-unique reads, detection of novel stable ncRNA transcripts and processing products and annotation of known transcripts based on multiple sources of information. To disclose the potential of APART, we have analyzed a cDNA library derived from small ribosome-associated RNAs in Saccharomyces cerevisiae. By employing the APART pipeline, we were able to detect and confirm by independent experimental methods multiple novel stable RNA molecules differentially processed from well known ncRNAs, like rRNAs, tRNAs or snoRNAs, in a stress-dependent manner.

Global effects of the CSR-1 RNA interference pathway on transcriptional landscape

PubMed Central

Cecere, Germano; Hoersch, Sebastian; O’Keeffe, Sean; Sachidanandam, Ravi; Grishok, Alla

2014-01-01

Argonaute proteins and their small RNA co-factors short interfering RNAs (siRNAs) are known to inhibit gene expression at the transcriptional and post-transcriptional levels. In Caenorhabditis elegans, the Argonaute CSR-1 binds thousands of endogenous siRNAs (endo-siRNAs) antisense to germline transcripts and associates with chromatin in a siRNA-dependent manner. However, its role in gene expression regulation remains controversial. Here, we used a genome-wide profiling of nascent RNA transcripts to demonstrate that the CSR-1 RNAi pathway promotes sense-oriented Pol II transcription. Moreover, a loss of CSR-1 function resulted in global increase in antisense transcription and ectopic transcription of silent chromatin domains, which led to reduced chromatin incorporation of centromere-specific histone H3. Based on these findings, we propose that the CSR-1 pathway has a role in maintaining the directionality of active transcription thereby propagating the distinction between transcriptionally active and silent genomic regions. PMID:24681887

5S rRNA and accompanying proteins in gonads: powerful markers to identify sex and reproductive endocrine disruption in fish.

PubMed

Diaz de Cerio, Oihane; Rojo-Bartolomé, Iratxe; Bizarro, Cristina; Ortiz-Zarragoitia, Maren; Cancio, Ibon

2012-07-17

In anuran ovaries, 5S rDNA is regulated transcriptionally by transcription factor IIIA (TFIIIA), which upon transcription, binds 5S rRNA, forming 7S RNP. 5S rRNA can be stockpiled also in the form of 42S RNP bound to 42sp43. The aim of the present study was to assess the differential transcriptional regulation of 5S rRNA and associated proteins in thicklip gray mullet (Chelon labrosus) gonads. Up to 75% of the total RNA from mullet ovaries was 5S rRNA. qPCR quantification of 5S rRNA expression, in gonads of histologically sexed individuals from different geographical areas, successfully sexed animals. All males had expression levels that were orders of magnitude below expression levels in females, throughout an annual reproductive cycle, with the exception of two individuals: one in November and one in December. Moreover, intersex mullets from a polluted harbor had expression levels between both sexes. TFIIIA and 42sp43 were also very active transcriptionally in gonads of female and intersex mullets, in comparison to males. Nucleocytoplasmatic transport is important in this context and we also analyzed transcriptional levels of importins-α1, -α2, and -β2 and different exportins. Importin-αs behaved similarly to 5S rRNA. Thus, 5S rRNA and associated proteins constitute very powerful molecular markers of sex and effects of xenosterogens in fish gonads, with potential technological applications in the analysis of fish stock dynamics and reproduction as well as in environmental health assessment.

Conserved Non-Coding Sequences are Associated with Rates of mRNA Decay in Arabidopsis.

PubMed

Spangler, Jacob B; Feltus, Frank Alex

2013-01-01

Steady-state mRNA levels are tightly regulated through a combination of transcriptional and post-transcriptional control mechanisms. The discovery of cis-acting DNA elements that encode these control mechanisms is of high importance. We have investigated the influence of conserved non-coding sequences (CNSs), DNA patterns retained after an ancient whole genome duplication event, on the breadth of gene expression and the rates of mRNA decay in Arabidopsis thaliana. The absence of CNSs near α duplicate genes was associated with a decrease in breadth of gene expression and slower mRNA decay rates while the presence CNSs near α duplicates was associated with an increase in breadth of gene expression and faster mRNA decay rates. The observed difference in mRNA decay rate was fastest in genes with CNSs in both non-transcribed and transcribed regions, albeit through an unknown mechanism. This study supports the notion that some Arabidopsis CNSs regulate the steady-state mRNA levels through post-transcriptional control mechanisms and that CNSs also play a role in controlling the breadth of gene expression.

Conserved Non-Coding Sequences are Associated with Rates of mRNA Decay in Arabidopsis

PubMed Central

Spangler, Jacob B.; Feltus, Frank Alex

2013-01-01

Steady-state mRNA levels are tightly regulated through a combination of transcriptional and post-transcriptional control mechanisms. The discovery of cis-acting DNA elements that encode these control mechanisms is of high importance. We have investigated the influence of conserved non-coding sequences (CNSs), DNA patterns retained after an ancient whole genome duplication event, on the breadth of gene expression and the rates of mRNA decay in Arabidopsis thaliana. The absence of CNSs near α duplicate genes was associated with a decrease in breadth of gene expression and slower mRNA decay rates while the presence CNSs near α duplicates was associated with an increase in breadth of gene expression and faster mRNA decay rates. The observed difference in mRNA decay rate was fastest in genes with CNSs in both non-transcribed and transcribed regions, albeit through an unknown mechanism. This study supports the notion that some Arabidopsis CNSs regulate the steady-state mRNA levels through post-transcriptional control mechanisms and that CNSs also play a role in controlling the breadth of gene expression. PMID:23675377

The association of TIF-IA and polymerase I mediates promoter recruitment and regulation of ribosomal RNA transcription in Acanthamoeba castellanii.

PubMed

Gogain, Joseph C; Paule, Marvin R

2005-01-01

Large amounts of energy are expended for the construction of the ribosome during both transcription and processing, so it is of utmost importance for the cell to efficiently regulate ribosome production. Understanding how this regulation occurs will provide important insights into cellular growth control and into the coordination of gene expression mediated by all three transcription systems. Ribosomal RNA (rRNA) transcription rates closely parallel the need for protein synthesis; as a cell approaches stationary phase or encounters conditions that negatively affect either growth rate or protein synthesis, rRNA transcription is decreased. In eukaryotes, the interaction of RNA polymerase I (pol I) with the essential transcription initiation factor IA (TIF-IA) has been implicated in this downregulation of transcription. In agreement with the first observation that rRNA transcription is regulated by altering recruitment of pol I to the promoter in Acanthamoeba castellanii, we show here that pol I and an 80-kDa homologue of TIF-IA are found tightly associated in pol I fractions competent for specific transcription. Disruption of the pol I-TIF-IA complex is mediated by a specific dephosphorylation of either pol I or TIF-IA. Phosphatase treatment of TIF-IA-containing A. castellanii pol I fractions results in a downregulation of both transcriptional activity and promoter binding, reminiscent of the inactive pol I fractions purified from encysted cells. The fraction of pol I competent for promoter recruitment is enriched in TIF-IA relative to that not bound by immobilized promoter DNA. This downregulation coincides with an altered electrophoretic mobility of TIF-IA, suggesting at least it is phosphorylated.

DNA replication initiator Cdc6 also regulates ribosomal DNA transcription initiation.

PubMed

Huang, Shijiao; Xu, Xiaowei; Wang, Guopeng; Lu, Guoliang; Xie, Wenbing; Tao, Wei; Zhang, Hongyin; Jiang, Qing; Zhang, Chuanmao

2016-04-01

RNA-polymerase-I-dependent ribosomal DNA (rDNA) transcription is fundamental to rRNA processing, ribosome assembly and protein synthesis. However, how this process is initiated during the cell cycle is not fully understood. By performing a proteomic analysis of transcription factors that bind RNA polymerase I during rDNA transcription initiation, we identified that the DNA replication initiator Cdc6 interacts with RNA polymerase I and its co-factors, and promotes rDNA transcription in G1 phase in an ATPase-activity-dependent manner. We further showed that Cdc6 is targeted to the nucleolus during late mitosis and G1 phase in a manner that is dependent on B23 (also known as nucleophosmin, NPM1), and preferentially binds to the rDNA promoter through its ATP-binding domain. Overexpression of Cdc6 increases rDNA transcription, whereas knockdown of Cdc6 results in a decreased association of both RNA polymerase I and the RNA polymerase I transcription factor RRN3 with rDNA, and a reduction of rDNA transcription. Furthermore, depletion of Cdc6 impairs the interaction between RRN3 and RNA polymerase I. Taken together, our data demonstrate that Cdc6 also serves as a regulator of rDNA transcription initiation, and indicate a mechanism by which initiation of rDNA transcription and DNA replication can be coordinated in cells. © 2016. Published by The Company of Biologists Ltd.

Regulatory consequences of neuronal ELAV-like protein binding to coding and non-coding RNAs in human brain

PubMed Central

Scheckel, Claudia; Drapeau, Elodie; Frias, Maria A; Park, Christopher Y; Fak, John; Zucker-Scharff, Ilana; Kou, Yan; Haroutunian, Vahram; Ma'ayan, Avi

2016-01-01

Neuronal ELAV-like (nELAVL) RNA binding proteins have been linked to numerous neurological disorders. We performed crosslinking-immunoprecipitation and RNAseq on human brain, and identified nELAVL binding sites on 8681 transcripts. Using knockout mice and RNAi in human neuroblastoma cells, we showed that nELAVL intronic and 3' UTR binding regulates human RNA splicing and abundance. We validated hundreds of nELAVL targets among which were important neuronal and disease-associated transcripts, including Alzheimer's disease (AD) transcripts. We therefore investigated RNA regulation in AD brain, and observed differential splicing of 150 transcripts, which in some cases correlated with differential nELAVL binding. Unexpectedly, the most significant change of nELAVL binding was evident on non-coding Y RNAs. nELAVL/Y RNA complexes were specifically remodeled in AD and after acute UV stress in neuroblastoma cells. We propose that the increased nELAVL/Y RNA association during stress may lead to nELAVL sequestration, redistribution of nELAVL target binding, and altered neuronal RNA splicing. DOI: http://dx.doi.org/10.7554/eLife.10421.001 PMID:26894958

Discovery of a novel oocyte-specific Krüppel-associated box domain-containing zinc finger protein required for early embryogenesis in cattle.

PubMed

Hand, Jacqelyn M; Zhang, Kun; Wang, Lei; Koganti, Prasanthi P; Mastrantoni, Kristen; Rajput, Sandeep K; Ashry, Mohamed; Smith, George W; Yao, Jianbo

2017-04-01

Zinc finger (ZNF) transcription factors interact with DNA through zinc finger motifs and play important roles in a variety of cellular functions including cell growth, proliferation, development, apoptosis, and intracellular signal transduction. One-third of ZNF proteins in metazoans contain a highly conserved N-terminal motif known as the Krüppel-associated box (KRAB) domain, which acts as a potent, DNA-binding dependent transcriptional repression module. Analysis of RNA-Seq data generated from a bovine oocyte cDNA library identified a novel transcript, which encodes a KRAB-containing ZNF transcription factor (named ZNFO). Characterization of ZNFO mRNA expression revealed that it is exclusively expressed in bovine oocytes and early embryos. A GFP reporter assay demonstrated that ZNFO protein localizes specifically to the nucleus, supporting its role in transcriptional regulation. To test the role of ZNFO in early embryonic development, zygotes were generated by in vitro maturation and fertilization of oocytes, and injected with small interfering RNA (siRNA) designed to knockdown ZNFO. Cleavage rates were not affected by ZNFO siRNA injection. However, embryonic development to 8- to 16-cell stage and blastocyst stage was significantly reduced relative to the uninjected and negative control siRNA-injected embryos. Further, interaction of ZNFO with the highly conserved co-factor, KRAB-associated protein-1 (KAP1), was demonstrated, and evidence supporting transcriptional repression by ZNFO was demonstrated using a GAL4-luciferase reporter system. Results of described studies demonstrate that ZNFO is a maternally-derived oocyte-specific nuclear factor required for early embryonic development in cattle, presumably functioning by repressing transcription. Copyright © 2017 Elsevier B.V. All rights reserved.

Fail-safe transcription termination: Because one is never enough

PubMed Central

Lemay, Jean-François; Bachand, François

2015-01-01

Termination of RNA polymerase II (RNAPII) transcription is a fundamental step of gene expression that involves the release of the nascent transcript and dissociation of RNAPII from the DNA template. As transcription termination is intimately linked to RNA 3′ end processing, termination pathways have a key decisive influence on the fate of the transcribed RNA. Quite remarkably, when reaching the 3′ end of genes, a substantial fraction of RNAPII fail to terminate transcription, requiring the contribution of alternative or “fail-safe” mechanisms of termination to release the polymerase. This point of view covers redundant mechanisms of transcription termination and how they relate to conventional termination models. In particular, we expand on recent findings that propose a reverse torpedo model of termination, in which the 3′5′ exonucleolytic activity of the RNA exosome targets transcription events associated with paused and backtracked RNAPII. PMID:26273910

Drosophila PAF1 Modulates PIWI/piRNA Silencing Capacity.

PubMed

Clark, Josef P; Rahman, Reazur; Yang, Nachen; Yang, Linda H; Lau, Nelson C

2017-09-11

To test the directness of factors in initiating PIWI-directed gene silencing, we employed a Piwi-interacting RNA (piRNA)-targeted reporter assay in Drosophila ovary somatic sheet (OSS) cells [1]. This assay confirmed direct silencing roles for piRNA biogenesis factors and PIWI-associated factors [2-12] but suggested that chromatin-modifying proteins may act downstream of the initial silencing event. Our data also revealed that RNA-polymerase-II-associated proteins like PAF1 and RTF1 antagonize PIWI-directed silencing. PAF1 knockdown enhances PIWI silencing of reporters when piRNAs target the transcript region proximal to the promoter. Loss of PAF1 suppresses endogenous transposable element (TE) transcript maturation, whereas a subset of gene transcripts and long-non-coding RNAs adjacent to TE insertions are affected by PAF1 knockdown in a similar fashion to piRNA-targeted reporters. Additionally, transcription activation at specific TEs and TE-adjacent loci during PIWI knockdown is suppressed when PIWI and PAF1 levels are both reduced. Our study suggests a mechanistic conservation between fission yeast PAF1 repressing AGO1/small interfering RNA (siRNA)-directed silencing [13, 14] and Drosophila PAF1 opposing PIWI/piRNA-directed silencing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Global analysis of A-to-I RNA editing reveals association with common disease variants

PubMed Central

Jain, Rajeev; Jain, Anamika; Betsholtz, Christer; Giannarelli, Chiara; Kovacic, Jason C.; Ruusalepp, Arno; Skogsberg, Josefin; Hao, Ke; Schadt, Eric E.

2018-01-01

RNA editing modifies transcripts and may alter their regulation or function. In humans, the most common modification is adenosine to inosine (A-to-I). We examined the global characteristics of RNA editing in 4,301 human tissue samples. More than 1.6 million A-to-I edits were identified in 62% of all protein-coding transcripts. mRNA recoding was extremely rare; only 11 novel recoding sites were uncovered. Thirty single nucleotide polymorphisms from genome-wide association studies were associated with RNA editing; one that influences type 2 diabetes (rs2028299) was associated with editing in ARPIN. Twenty-five genes, including LRP11 and PLIN5, had editing sites that were associated with plasma lipid levels. Our findings provide new insights into the genetic regulation of RNA editing and establish a rich catalogue for further exploration of this process. PMID:29527417

A Function for the hnRNP A1/A2 Proteins in Transcription Elongation.

PubMed

Lemieux, Bruno; Blanchette, Marco; Monette, Anne; Mouland, Andrew J; Wellinger, Raymund J; Chabot, Benoit

2015-01-01

The hnRNP A1 and A2 proteins regulate processes such as alternative pre-mRNA splicing and mRNA stability. Here, we report that a reduction in the levels of hnRNP A1 and A2 by RNA interference or their cytoplasmic retention by osmotic stress drastically increases the transcription of a reporter gene. Based on previous work, we propose that this effect may be linked to a decrease in the activity of the transcription elongation factor P-TEFb. Consistent with this hypothesis, the transcription of the reporter gene was stimulated when the catalytic component of P-TEFb, CDK9, was inhibited with DRB. While low levels of A1/A2 stimulated the association of RNA polymerase II with the reporter gene, they also increased the association of CDK9 with the repressor 7SK RNA, and compromised the recovery of promoter-distal transcription on the Kitlg gene after the release of pausing. Transcriptome analysis revealed that more than 50% of the genes whose expression was affected by the siRNA-mediated depletion of A1/A2 were also affected by DRB. RNA polymerase II-chromatin immunoprecipitation assays on DRB-treated and A1/A2-depleted cells identified a common set of repressed genes displaying increased occupancy of polymerases at promoter-proximal locations, consistent with pausing. Overall, our results suggest that lowering the levels of hnRNP A1/A2 elicits defective transcription elongation on a fraction of P-TEFb-dependent genes, hence favoring the transcription of P-TEFb-independent genes.

La protein and its associated small nuclear and nucleolar precursor RNAs.

PubMed

Maraia, Richard J; Intine, Robert V

2002-01-01

After transcription by RNA polymerase (pol) III, nascent Pol III transcripts pass through RNA processing, modification, and transport machineries as part of their posttranscriptional maturation process. The first factor to interact with Pol III transcripts is La protein, which binds principally via its conserved N-terminal domain (NTD), to the UUU-OH motif that results from transcription termination. This review includes a sequence Logo of the most conserved region of La and its refined modeling as an RNA recognition motif (RRM). La protects RNAs from 3' exonucleolytic digestion and also contributes to their nuclear retention. The variety of modifications found on La-associated RNAs is reviewed in detail and considered in the contexts of how La may bind the termini of structured RNAs without interfering with recognition by modification enzymes, and its ability to chaperone RNAs through multiple parts of their maturation pathways. The CTD of human La recognizes the 5' end region of nascent RNA in a manner that is sensitive to serine 366 phosphorylation. Although the CTD can control pre-tRNA cleavage by RNase P, a rate-limiting step in tRNASerUGA maturation, the extent to which it acts in the maturation pathway(s) of other transcripts is unknown but considered here. Evidence that a fraction of La resides in the nucleolus together with recent findings that several Pol III transcripts pass through the nucleolus is also reviewed. An imminent goal is to understand how the bipartite RNA binding, intracellular trafficking, and signal transduction activities of La are integrated with the maturation pathways of the various RNAs with which it associates.

Multiple Transcript Properties Related to Translation Affect mRNA Degradation Rates in Saccharomyces cerevisiae

PubMed Central

Neymotin, Benjamin; Ettorre, Victoria; Gresham, David

2016-01-01

Degradation of mRNA contributes to variation in transcript abundance. Studies of individual mRNAs have shown that both cis and trans factors affect mRNA degradation rates. However, the factors underlying transcriptome-wide variation in mRNA degradation rates are poorly understood. We investigated the contribution of different transcript properties to transcriptome-wide degradation rate variation in the budding yeast, Saccharomyces cerevisiae, using multiple regression analysis. We find that multiple transcript properties are significantly associated with variation in mRNA degradation rates, and that a model incorporating these properties explains ∼50% of the genome-wide variance. Predictors of mRNA degradation rates include transcript length, ribosome density, biased codon usage, and GC content of the third position in codons. To experimentally validate these factors, we studied individual transcripts expressed from identical promoters. We find that decreasing ribosome density by mutating the first translational start site of a transcript increases its degradation rate. Using coding sequence variants of green fluorescent protein (GFP) that differ only at synonymous sites, we show that increased GC content of the third position of codons results in decreased rates of mRNA degradation. Thus, in steady-state conditions, a large fraction of genome-wide variation in mRNA degradation rates is determined by inherent properties of transcripts, many of which are related to translation, rather than specific regulatory mechanisms. PMID:27633789

Global profiling of alternative RNA splicing events provides insights into molecular differences between various types of hepatocellular carcinoma.

PubMed

Tremblay, Marie-Pier; Armero, Victoria E S; Allaire, Andréa; Boudreault, Simon; Martenon-Brodeur, Camille; Durand, Mathieu; Lapointe, Elvy; Thibault, Philippe; Tremblay-Létourneau, Maude; Perreault, Jean-Pierre; Scott, Michelle S; Bisaillon, Martin

2016-08-26

Dysregulations in alternative splicing (AS) patterns have been associated with many human diseases including cancer. In the present study, alterations to the global RNA splicing landscape of cellular genes were investigated in a large-scale screen from 377 liver tissue samples using high-throughput RNA sequencing data. Our study identifies modifications in the AS patterns of transcripts encoded by more than 2500 genes such as tumor suppressor genes, transcription factors, and kinases. These findings provide insights into the molecular differences between various types of hepatocellular carcinoma (HCC). Our analysis allowed the identification of 761 unique transcripts for which AS is misregulated in HBV-associated HCC, while 68 are unique to HCV-associated HCC, 54 to HBV&HCV-associated HCC, and 299 to virus-free HCC. Moreover, we demonstrate that the expression pattern of the RNA splicing factor hnRNPC in HCC tissues significantly correlates with patient survival. We also show that the expression of the HBx protein from HBV leads to modifications in the AS profiles of cellular genes. Finally, using RNA interference and a reverse transcription-PCR screening platform, we examined the implications of cellular proteins involved in the splicing of transcripts involved in apoptosis and demonstrate the potential contribution of these proteins in AS control. This study provides the first comprehensive portrait of global changes in the RNA splicing signatures that occur in hepatocellular carcinoma. Moreover, these data allowed us to identify unique signatures of genes for which AS is misregulated in the different types of HCC.

Environmental contaminants and microRNA regulation: Transcription factors as regulators of toxicant-altered microRNA expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sollome, James; Martin, Elizabeth

MicroRNAs (miRNAs) regulate gene expression by binding mRNA and inhibiting translation and/or inducing degradation of the associated transcripts. Expression levels of miRNAs have been shown to be altered in response to environmental toxicants, thus impacting cellular function and influencing disease risk. Transcription factors (TFs) are known to be altered in response to environmental toxicants and play a critical role in the regulation of miRNA expression. To date, environmentally-responsive TFs that are important for regulating miRNAs remain understudied. In a state-of-the-art analysis, we utilized an in silico bioinformatic approach to characterize potential transcriptional regulators of environmentally-responsive miRNAs. Using the miRStart database,more » genomic sequences of promoter regions for all available human miRNAs (n = 847) were identified and promoter regions were defined as − 1000/+500 base pairs from the transcription start site. Subsequently, the promoter region sequences of environmentally-responsive miRNAs (n = 128) were analyzed using enrichment analysis to determine overrepresented TF binding sites (TFBS). While most (56/73) TFs differed across environmental contaminants, a set of 17 TFs was enriched for promoter binding among miRNAs responsive to numerous environmental contaminants. Of these, one TF was common to miRNAs altered by the majority of environmental contaminants, namely SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 3 (SMARCA3). These identified TFs represent candidate common transcriptional regulators of miRNAs perturbed by environmental toxicants. - Highlights: • Transcription factors that regulate environmentally-modulated miRNA expression are understudied • Transcription factor binding sites (TFBS) located within DNA promoter regions of miRNAs were identified. • Specific transcription factors may serve as master regulators of environmentally-mediated microRNA expression.« less

Location of rRNA transcription to the nucleolar components: disappearance of the fibrillar centers in nucleoli of regenerating rat hepatocytes.

PubMed

Montanaro, Lorenzo; Govoni, Marzia; Orrico, Catia; Treré, Davide; Derenzini, Massimo

2011-01-01

The precise location of rDNA transcription to the components of mammalian cell nucleolus is still debated. This was due to the fact that all the molecules necessary for rRNA synthesis are located in two of the three components, the fibrillar centers (FCs) and the dense fibrillar component (DFC), which together with the granular component (GC) are considered to be constantly present in mammalian cell nucleoli. In the present study we demonstrated that in nucleoli of many regenerating rat hepatocytes at 15 h after partial hepatectomy the FCs were no longer present, only the DFC and the GC being detected. At this time of regeneration the rRNA transcriptional activity was three fold that of resting hepatocytes, while the synthesis of DNA was not yet significantly increased, indicating that these nucleolar changes were due to the rRNA synthesis up-regulation. The DFC appeared to be organized in numerous, small, roundish tufts of fibrils. The silver staining procedure for AgNOR proteins, which are associated with the ribosomal genes, selectively and homogeneously stained these fibrillar tufts. Immuno-gold visualization of the Upstream Binding Factor (UBF), which is associated with the promoter region and the transcribed portion of the rRNA 45S gene, demonstrated that UBF was selectively located in the fibrillar tufts. We concluded that in proliferating rat hepatocytes the increased synthesis of rRNA induced an activation of the rRNA transcription machinery located in the fibrillar centers which, by becoming associated with the ribonucleoprotein transcripts, assumed the morphological pattern of the DFC.

BEND3 represses rDNA transcription by stabilizing a NoRC component via USP21 deubiquitinase

PubMed Central

Khan, Abid; Giri, Sumanprava; Wang, Yating; Chakraborty, Arindam; Ghosh, Archit K.; Anantharaman, Aparna; Aggarwal, Vasudha; Sathyan, Kizhakke M.; Ha, Taekjip; Prasanth, Kannanganattu V.; Prasanth, Supriya G.

2015-01-01

Ribosome biogenesis dictates the translational capacity of cells. Several mechanisms establish and maintain transcriptional output from eukaryotic ribosomal DNA (rDNA) loci. rDNA silencing is one such mechanism that ensures the inactivity and hence the maintenance of a silenced state of a subset of rRNA gene copies. Whereas oncogenic agents stimulate rRNA gene transcription, tumor suppressors decrease rRNA gene transcription. We demonstrate in mammalian cells that BANP, E5R, and Nac1 (BEN) domain 3 (BEND3), a quadruple BEN domain-containing protein, localizes in nucleoli and binds to ribosomal RNA gene promoters to help repress rRNA genes. Loss of BEND3 increases histone H3K4 trimethylation and, correspondingly, decreases rDNA promoter DNA methylation, consistent with a role for BEND3 in rDNA silencing. BEND3 associates with the nucleolar-remodeling complex (NoRC), and SUMOylated BEND3 stabilizes NoRC component TTF-1–interacting protein 5 via association with ubiquitin specific protease 21 (USP21) debiquitinase. Our results provide mechanistic insights into how the novel rDNA transcription repressor BEND3 acts together with NoRC to actively coordinate the establishment of rDNA silencing. PMID:26100909

BEND3 represses rDNA transcription by stabilizing a NoRC component via USP21 deubiquitinase.

PubMed

Khan, Abid; Giri, Sumanprava; Wang, Yating; Chakraborty, Arindam; Ghosh, Archit K; Anantharaman, Aparna; Aggarwal, Vasudha; Sathyan, Kizhakke M; Ha, Taekjip; Prasanth, Kannanganattu V; Prasanth, Supriya G

2015-07-07

Ribosome biogenesis dictates the translational capacity of cells. Several mechanisms establish and maintain transcriptional output from eukaryotic ribosomal DNA (rDNA) loci. rDNA silencing is one such mechanism that ensures the inactivity and hence the maintenance of a silenced state of a subset of rRNA gene copies. Whereas oncogenic agents stimulate rRNA gene transcription, tumor suppressors decrease rRNA gene transcription. We demonstrate in mammalian cells that BANP, E5R, and Nac1 (BEN) domain 3 (BEND3), a quadruple BEN domain-containing protein, localizes in nucleoli and binds to ribosomal RNA gene promoters to help repress rRNA genes. Loss of BEND3 increases histone H3K4 trimethylation and, correspondingly, decreases rDNA promoter DNA methylation, consistent with a role for BEND3 in rDNA silencing. BEND3 associates with the nucleolar-remodeling complex (NoRC), and SUMOylated BEND3 stabilizes NoRC component TTF-1-interacting protein 5 via association with ubiquitin specific protease 21 (USP21) debiquitinase. Our results provide mechanistic insights into how the novel rDNA transcription repressor BEND3 acts together with NoRC to actively coordinate the establishment of rDNA silencing.

Transient dissociation of polyribosomes and concurrent recruitment of calreticulin and calmodulin transcripts in gravistimulated maize pulvini

NASA Technical Reports Server (NTRS)

Heilmann, I.; Shin, J.; Huang, J.; Perera, I. Y.; Davies, E.

2001-01-01

The dynamics of polyribosome abundance were studied in gravistimulated maize (Zea mays) stem pulvini. During the initial 15 min of gravistimulation, the amount of large polyribosomes transiently decreased. The transient decrease in polyribosome levels was accompanied by a transient decrease in polyribosome-associated mRNA. After 30 min of gravistimulation, the levels of polyribosomes and the amount of polyribosome-associated mRNA gradually increased over 24 h up to 3- to 4-fold of the initial value. Within 15 min of gravistimulation, total levels of transcripts coding for calreticulin and calmodulin were elevated 5-fold in maize pulvinus total RNA. Transcripts coding for calreticulin and calmodulin were recruited into polyribosomes within 15 min of gravistimulation. Over 4 h of gravistimulation, a gradual increase in the association of calreticulin and calmodulin transcripts with polyribosomes was seen predominantly in the lower one-half of the maize pulvinus; the association of transcripts for vacuolar invertase with polyribosomes did not change over this period. Our results suggest that within 15 min of gravistimulation, the translation of the majority of transcripts associated with polyribosomes decreased, resembling a general stress response. Recruitment of calreticulin and calmodulin transcripts into polyribosomes occurred predominantly in the lower pulvinus one-half during the first 4 h when the presentation time for gravistimulation in the maize pulvinus is not yet complete.

The point of no return: The poly(A)-associated elongation checkpoint.

PubMed

Tellier, Michael; Ferrer-Vicens, Ivan; Murphy, Shona

2016-01-01

Cyclin-dependent kinases play critical roles in transcription by RNA polymerase II (pol II) and processing of the transcripts. For example, CDK9 regulates transcription of protein-coding genes, splicing, and 3' end formation of the transcripts. Accordingly, CDK9 inhibitors have a drastic effect on the production of mRNA in human cells. Recent analyses indicate that CDK9 regulates transcription at the early-elongation checkpoint of the vast majority of pol II-transcribed genes. Our recent discovery of an additional CDK9-regulated elongation checkpoint close to poly(A) sites adds a new layer to the control of transcription by this critical cellular kinase. This novel poly(A)-associated checkpoint has the potential to powerfully regulate gene expression just before a functional polyadenylated mRNA is produced: the point of no return. However, many questions remain to be answered before the role of this checkpoint becomes clear. Here we speculate on the possible biological significance of this novel mechanism of gene regulation and the players that may be involved.

The Conserved Foot Domain of RNA Pol II Associates with Proteins Involved in Transcriptional Initiation and/or Early Elongation

PubMed Central

García-López, M. Carmen; Pelechano, Vicent; Mirón-García, M. Carmen; Garrido-Godino, Ana I.; García, Alicia; Calvo, Olga; Werner, Michel; Pérez-Ortín, José E.; Navarro, Francisco

2011-01-01

RNA polymerase (pol) II establishes many protein–protein interactions with transcriptional regulators to coordinate different steps of transcription. Although some of these interactions have been well described, little is known about the existence of RNA pol II regions involved in contact with transcriptional regulators. We hypothesize that conserved regions on the surface of RNA pol II contact transcriptional regulators. We identified such an RNA pol II conserved region that includes the majority of the “foot” domain and identified interactions of this region with Mvp1, a protein required for sorting proteins to the vacuole, and Spo14, a phospholipase D. Deletion of MVP1 and SPO14 affects the transcription of their target genes and increases phosphorylation of Ser5 in the carboxy-terminal domain (CTD). Genetic, phenotypic, and functional analyses point to a role for these proteins in transcriptional initiation and/or early elongation, consistent with their genetic interactions with CEG1, a guanylyltransferase subunit of the Saccharomyces cerevisiae capping enzyme. PMID:21954159

A microRNA feedback loop regulates global microRNA abundance during aging.

PubMed

Inukai, Sachi; Pincus, Zachary; de Lencastre, Alexandre; Slack, Frank J

2018-02-01

Expression levels of many microRNAs (miRNAs) change during aging, notably declining globally in a number of organisms and tissues across taxa. However, little is known about the mechanisms or the biological relevance for this change. We investigated the network of genes that controls miRNA transcription and processing during C. elegans aging. We found that miRNA biogenesis genes are highly networked with transcription factors and aging-associated miRNAs. In particular, miR-71, known to influence life span and itself up-regulated during aging, represses alg-1 /Argonaute expression post-transcriptionally during aging. Increased ALG-1 abundance in mir-71 loss-of-function mutants led to globally increased miRNA expression. Interestingly, these mutants demonstrated widespread mRNA expression dysregulation and diminished levels of variability both in gene expression and in overall life span. Thus, the progressive molecular decline often thought to be the result of accumulated damage over an organism's life may be partially explained by a miRNA-directed mechanism of age-associated decline. © 2018 Inukai et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

The 7SK snRNP associates with the little elongation complex to promote snRNA gene expression.

PubMed

Egloff, Sylvain; Vitali, Patrice; Tellier, Michael; Raffel, Raoul; Murphy, Shona; Kiss, Tamás

2017-04-03

The 7SK small nuclear RNP (snRNP), composed of the 7SK small nuclear RNA (snRNA), MePCE, and Larp7, regulates the mRNA elongation capacity of RNA polymerase II (RNAPII) through controlling the nuclear activity of positive transcription elongation factor b (P-TEFb). Here, we demonstrate that the human 7SK snRNP also functions as a canonical transcription factor that, in collaboration with the little elongation complex (LEC) comprising ELL, Ice1, Ice2, and ZC3H8, promotes transcription of RNAPII-specific spliceosomal snRNA and small nucleolar RNA (snoRNA) genes. The 7SK snRNA specifically associates with a fraction of RNAPII hyperphosphorylated at Ser5 and Ser7, which is a hallmark of RNAPII engaged in snRNA synthesis. Chromatin immunoprecipitation (ChIP) and chromatin isolation by RNA purification (ChIRP) experiments revealed enrichments for all components of the 7SK snRNP on RNAPII-specific sn/snoRNA genes. Depletion of 7SK snRNA or Larp7 disrupts LEC integrity, inhibits RNAPII recruitment to RNAPII-specific sn/snoRNA genes, and reduces nascent snRNA and snoRNA synthesis. Thus, through controlling both mRNA elongation and sn/snoRNA synthesis, the 7SK snRNP is a key regulator of nuclear RNA production by RNAPII. © 2017 The Authors.

mRNA quality control is bypassed for immediate export of stress-responsive transcripts.

PubMed

Zander, Gesa; Hackmann, Alexandra; Bender, Lysann; Becker, Daniel; Lingner, Thomas; Salinas, Gabriela; Krebber, Heike

2016-12-12

Cells grow well only in a narrow range of physiological conditions. Surviving extreme conditions requires the instantaneous expression of chaperones that help to overcome stressful situations. To ensure the preferential synthesis of these heat-shock proteins, cells inhibit transcription, pre-mRNA processing and nuclear export of non-heat-shock transcripts, while stress-specific mRNAs are exclusively exported and translated. How cells manage the selective retention of regular transcripts and the simultaneous rapid export of heat-shock mRNAs is largely unknown. In Saccharomyces cerevisiae, the shuttling RNA adaptor proteins Npl3, Gbp2, Hrb1 and Nab2 are loaded co-transcriptionally onto growing pre-mRNAs. For nuclear export, they recruit the export-receptor heterodimer Mex67-Mtr2 (TAP-p15 in humans). Here we show that cellular stress induces the dissociation of Mex67 and its adaptor proteins from regular mRNAs to prevent general mRNA export. At the same time, heat-shock mRNAs are rapidly exported in association with Mex67, without the need for adapters. The immediate co-transcriptional loading of Mex67 onto heat-shock mRNAs involves Hsf1, a heat-shock transcription factor that binds to heat-shock-promoter elements in stress-responsive genes. An important difference between the export modes is that adaptor-protein-bound mRNAs undergo quality control, whereas stress-specific transcripts do not. In fact, regular mRNAs are converted into uncontrolled stress-responsive transcripts if expressed under the control of a heat-shock promoter, suggesting that whether an mRNA undergoes quality control is encrypted therein. Under normal conditions, Mex67 adaptor proteins are recruited for RNA surveillance, with only quality-controlled mRNAs allowed to associate with Mex67 and leave the nucleus. Thus, at the cost of error-free mRNA formation, heat-shock mRNAs are exported and translated without delay, allowing cells to survive extreme situations.

Systematically frameshifting by deletion of every 4th or 4th and 5th nucleotides during mitochondrial transcription: RNA self-hybridization regulates delRNA expression.

PubMed

Seligmann, Hervé

2016-01-01

In mitochondria, secondary structures punctuate post-transcriptional RNA processing. Recently described transcripts match the human mitogenome after systematic deletions of every 4th, respectively every 4th and 5th nucleotides, called delRNAs. Here I explore predicted stem-loop hairpin formation by delRNAs, and their associations with delRNA transcription and detected peptides matching their translation. Despite missing 25, respectively 40% of the nucleotides in the original sequence, del-transformed sequences form significantly more secondary structures than corresponding randomly shuffled sequences, indicating biological function, independently of, and in combination with, previously detected delRNA and thereof translated peptides. Self-hybridization decreases delRNA abundances, indicating downregulation. Systematic deletions of the human mitogenome reveal new, unsuspected coding and structural informations. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Characterization of a spliced exon product of herpes simplex type-1 latency-associated transcript in productively infected cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Wen; Mukerjee, Ruma; Gartner, Jared J.

2006-12-20

The latency-associated transcripts (LATs) of herpes simplex virus type-1 (HSV-1) are the only viral RNAs accumulating during latent infections in the sensory ganglia of the peripheral nervous system. The major form of LAT that accumulates in latently infected neurons is a 2 kb intron, spliced from a much less abundant 8.3 primary transcript. The spliced exon mRNA has been hard to detect. However, in this study, we have examined the spliced exon RNA in productively infected cells using ribonuclease protection (RPA), and quantitative RT-PCR (q-PCR) assays. We were able to detect the LAT exon RNA in productively infected SY5Y cellsmore » (a human neuronal cell line). The level of the LAT exon RNA was found to be approximately 5% that of the 2 kb intron RNA and thus is likely to be relatively unstable. Quantitative RT-PCR (q-PCR) assays were used to examine the LAT exon RNA and its properties. They confirmed that the LAT exon mRNA is present at a very low level in productively infected cells, compared to the levels of other viral transcripts. Furthermore, experiments showed that the LAT exon mRNA is expressed as a true late gene, and appears to be polyadenylated. In SY5Y cells, in contrast to most late viral transcripts, the LAT exon RNA was found to be mainly nuclear localized during the late stage of a productive infection. Interestingly, more LAT exon RNA was found in the cytoplasm in differentiated compared to undifferentiated SY5Y cells, suggesting the nucleocytoplasmic distribution of the LAT exon RNA and its related function may be influenced by the differentiation state of cells.« less

Pervasive Targeting of Nascent Transcripts by Hfq.

PubMed

Kambara, Tracy K; Ramsey, Kathryn M; Dove, Simon L

2018-05-01

Hfq is an RNA chaperone and an important post-transcriptional regulator in bacteria. Using chromatin immunoprecipitation coupled with high-throughput DNA sequencing (ChIP-seq), we show that Hfq associates with hundreds of different regions of the Pseudomonas aeruginosa chromosome. These associations are abolished when transcription is inhibited, indicating that they reflect Hfq binding to transcripts during their synthesis. Analogous ChIP-seq analyses with the post-transcriptional regulator Crc reveal that it associates with many of the same nascent transcripts as Hfq, an activity we show is Hfq dependent. Our findings indicate that Hfq binds many transcripts co-transcriptionally in P. aeruginosa, often in concert with Crc, and uncover direct regulatory targets of these proteins. They also highlight a general approach for studying the interactions of RNA-binding proteins with nascent transcripts in bacteria. The binding of post-transcriptional regulators to nascent mRNAs may represent a prevalent means of controlling translation in bacteria where transcription and translation are coupled. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Post-transcriptional gene silencing triggered by sense transgenes involves uncapped antisense RNA and differs from silencing intentionally triggered by antisense transgenes

PubMed Central

Parent, Jean-Sébastien; Jauvion, Vincent; Bouché, Nicolas; Béclin, Christophe; Hachet, Mélanie; Zytnicki, Matthias; Vaucheret, Hervé

2015-01-01

Although post-transcriptional gene silencing (PTGS) has been studied for more than a decade, there is still a gap in our understanding of how de novo silencing is initiated against genetic elements that are not supposed to produce double-stranded (ds)RNA. Given the pervasive transcription occurring throughout eukaryote genomes, we tested the hypothesis that unintended transcription could produce antisense (as)RNA molecules that participate to the initiation of PTGS triggered by sense transgenes (S-PTGS). Our results reveal a higher level of asRNA in Arabidopsis thaliana lines that spontaneously trigger S-PTGS than in lines that do not. However, PTGS triggered by antisense transgenes (AS-PTGS) differs from S-PTGS. In particular, a hypomorphic ago1 mutation that suppresses S-PTGS prevents the degradation of asRNA but not sense RNA during AS-PTGS, suggesting a different treatment of coding and non-coding RNA by AGO1, likely because of AGO1 association to polysomes. Moreover, the intended asRNA produced during AS-PTGS is capped whereas the asRNA produced during S-PTGS derives from 3′ maturation of a read-through transcript and is uncapped. Thus, we propose that uncapped asRNA corresponds to the aberrant RNA molecule that is converted to dsRNA by RNA-DEPENDENT RNA POLYMERASE 6 in siRNA-bodies to initiate S-PTGS, whereas capped asRNA must anneal with sense RNA to produce dsRNA that initiate AS-PTGS. PMID:26209135

Activating RNAs associate with Mediator to enhance chromatin architecture and transcription.

PubMed

Lai, Fan; Orom, Ulf A; Cesaroni, Matteo; Beringer, Malte; Taatjes, Dylan J; Blobel, Gerd A; Shiekhattar, Ramin

2013-02-28

Recent advances in genomic research have revealed the existence of a large number of transcripts devoid of protein-coding potential in multiple organisms. Although the functional role for long non-coding RNAs (lncRNAs) has been best defined in epigenetic phenomena such as X-chromosome inactivation and imprinting, different classes of lncRNAs may have varied biological functions. We and others have identified a class of lncRNAs, termed ncRNA-activating (ncRNA-a), that function to activate their neighbouring genes using a cis-mediated mechanism. To define the precise mode by which such enhancer-like RNAs function, we depleted factors with known roles in transcriptional activation and assessed their role in RNA-dependent activation. Here we report that depletion of the components of the co-activator complex, Mediator, specifically and potently diminished the ncRNA-induced activation of transcription in a heterologous reporter assay using human HEK293 cells. In vivo, Mediator is recruited to ncRNA-a target genes and regulates their expression. We show that ncRNA-a interact with Mediator to regulate its chromatin localization and kinase activity towards histone H3 serine 10. The Mediator complex harbouring disease- displays diminished ability to associate with activating ncRNAs. Chromosome conformation capture confirmed the presence of DNA looping between the ncRNA-a loci and its targets. Importantly, depletion of Mediator subunits or ncRNA-a reduced the chromatin looping between the two loci. Our results identify the human Mediator complex as the transducer of activating ncRNAs and highlight the importance of Mediator and activating ncRNA association in human disease.

Conformational changes accompany activation of reovirus RNA-dependent RNA transcription

PubMed Central

Mendez, Israel I.; Weiner, Scott G.; She, Yi-Min; Yeager, Mark; Coombs, Kevin M.

2009-01-01

Many critical biologic processes involve dynamic interactions between proteins and nucleic acids. Such dynamic processes are often difficult to delineate by conventional static methods. For example, while a variety of nucleic acid polymerase structures have been determined at atomic resolution, the details of how some multi-protein transcriptase complexes actively produce mRNA, as well as conformational changes associated with activation of such complexes, remain poorly understood. The mammalian reovirus innermost capsid (core) manifests all enzymatic activities necessary to produce mRNA from each of the 10 encased double-stranded RNA genes. We used rapid freezing and electron cryo-microscopy to trap and visualize transcriptionally active reovirus core particles and compared them to inactive core images. Rod-like density centered within actively transcribing core spike channels was attributed to exiting nascent mRNA. Comparative radial density plots of active and inactive core particles identified several structural changes in both internal and external regions of the icosahedral core capsid. Inactive and transcriptionally active cores were partially digested with trypsin and identities of initial tryptic peptides determined by mass spectrometry. Differentially-digested peptides, which also suggest transcription-associated conformational changes, were placed within the known 3-dimensional structures of major core proteins. PMID:18321727

Acetylation of TAF(I)68, a subunit of TIF-IB/SL1, activates RNA polymerase I transcription.

PubMed

Muth, V; Nadaud, S; Grummt, I; Voit, R

2001-03-15

Mammalian rRNA genes are preceded by a terminator element that is recognized by the transcription termination factor TTF-I. In exploring the functional significance of the promoter-proximal terminator, we found that TTF-I associates with the p300/CBP-associated factor PCAF, suggesting that TTF-I may target histone acetyltransferase to the rDNA promoter. We demonstrate that PCAF acetylates TAF(I)68, the second largest subunit of the TATA box-binding protein (TBP)-containing factor TIF-IB/SL1, and acetylation enhances binding of TAF(I)68 to the rDNA promoter. Moreover, PCAF stimulates RNA polymerase I (Pol I) transcription in a reconstituted in vitro system. Consistent with acetylation of TIF-IB/SL1 being required for rDNA transcription, the NAD(+)-dependent histone deacetylase mSir2a deacetylates TAF(I)68 and represses Pol I transcription. The results demonstrate that acetylation of the basal Pol I transcription machinery has functional consequences and suggest that reversible acetylation of TIF-IB/SL1 may be an effective means to regulate rDNA transcription in response to external signals.

Influenza Virus Mounts a Two-Pronged Attack on Host RNA Polymerase II Transcription.

PubMed

Bauer, David L V; Tellier, Michael; Martínez-Alonso, Mónica; Nojima, Takayuki; Proudfoot, Nick J; Murphy, Shona; Fodor, Ervin

2018-05-15

Influenza virus intimately associates with host RNA polymerase II (Pol II) and mRNA processing machinery. Here, we use mammalian native elongating transcript sequencing (mNET-seq) to examine Pol II behavior during viral infection. We show that influenza virus executes a two-pronged attack on host transcription. First, viral infection causes decreased Pol II gene occupancy downstream of transcription start sites. Second, virus-induced cellular stress leads to a catastrophic failure of Pol II termination at poly(A) sites, with transcription often continuing for tens of kilobases. Defective Pol II termination occurs independently of the ability of the viral NS1 protein to interfere with host mRNA processing. Instead, this termination defect is a common effect of diverse cellular stresses and underlies the production of previously reported downstream-of-gene transcripts (DoGs). Our work has implications for understanding not only host-virus interactions but also fundamental aspects of mammalian transcription. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

New Face for Chromatin-Related Mesenchymal Modulator: n-CHD9 Localizes to Nucleoli and Interacts With Ribosomal Genes.

PubMed

Salomon-Kent, Ronit; Marom, Ronit; John, Sam; Dundr, Miroslav; Schiltz, Louis R; Gutierrez, Jose; Workman, Jerry; Benayahu, Dafna; Hager, Gordon L

2015-09-01

Mesenchymal stem cells' differentiation into several lineages is coordinated by a complex of transcription factors and co-regulators which bind to specific gene promoters. The Chromatin-Related Mesenchymal Modulator, CHD9 demonstrated in vitro its ability for remodeling activity to reposition nucleosomes in an ATP-dependent manner. Epigenetically, CHD9 binds with modified H3-(K9me2/3 and K27me3). Previously, we presented a role for CHD9 with RNA Polymerase II (Pol II)-dependent transcription of tissue specific genes. Far less is known about CHD9 function in RNA Polymerase I (Pol I) related transcription of the ribosomal locus that also drives specific cell fate. We here describe a new form, the nucleolar CHD9 (n-CHD9) that is dynamically associated with Pol I, fibrillarin, and upstream binding factor (UBF) in the nucleoli, as shown by imaging and molecular approaches. Inhibitors of transcription disorganized the nucleolar compartment of transcription sites where rDNA is actively transcribed. Collectively, these findings link n-CHD9 with RNA pol I transcription in fibrillar centers. Using chromatin immunoprecipitation (ChIP) and tilling arrays (ChIP- chip), we find an association of n-CHD9 with Pol I related to rRNA biogenesis. Our new findings support the role for CHD9 in chromatin regulation and association with rDNA genes, in addition to its already known function in transcription control of tissue specific genes. © 2015 Wiley Periodicals, Inc.

Landscape of DNA Virus Associations across Human Malignant Cancers: Analysis of 3,775 Cases Using RNA-Seq

PubMed Central

Tannir, Nizar M.; Williams, Michelle D.; Chen, Yunxin; Yao, Hui; Zhang, Jianping; Thompson, Erika J.; Meric-Bernstam, Funda; Medeiros, L. Jeffrey; Weinstein, John N.

2013-01-01

Elucidation of tumor-DNA virus associations in many cancer types has enhanced our knowledge of fundamental oncogenesis mechanisms and provided a basis for cancer prevention initiatives. RNA-Seq is a novel tool to comprehensively assess such associations. We interrogated RNA-Seq data from 3,775 malignant neoplasms in The Cancer Genome Atlas database for the presence of viral sequences. Viral integration sites were also detected in expressed transcripts using a novel approach. The detection capacity of RNA-Seq was compared to available clinical laboratory data. Human papillomavirus (HPV) transcripts were detected using RNA-Seq analysis in head-and-neck squamous cell carcinoma, uterine endometrioid carcinoma, and squamous cell carcinoma of the lung. Detection of HPV by RNA-Seq correlated with detection by in situ hybridization and immunohistochemistry in squamous cell carcinoma tumors of the head and neck. Hepatitis B virus and Epstein-Barr virus (EBV) were detected using RNA-Seq in hepatocellular carcinoma and gastric carcinoma tumors, respectively. Integration sites of viral genes and oncogenes were detected in cancers harboring HPV or hepatitis B virus but not in EBV-positive gastric carcinoma. Integration sites of expressed viral transcripts frequently involved known coding areas of the host genome. No DNA virus transcripts were detected in acute myeloid leukemia, cutaneous melanoma, low- and high-grade gliomas of the brain, and adenocarcinomas of the breast, colon and rectum, lung, prostate, ovary, kidney, and thyroid. In conclusion, this study provides a large-scale overview of the landscape of DNA viruses in human malignant cancers. While further validation is necessary for specific cancer types, our findings highlight the utility of RNA-Seq in detecting tumor-associated DNA viruses and identifying viral integration sites that may unravel novel mechanisms of cancer pathogenesis. PMID:23740984

The yeast prefoldin-like URI-orthologue Bud27 associates with the RSC nucleosome remodeler and modulates transcription

PubMed Central

Mirón-García, María Carmen; Garrido-Godino, Ana Isabel; Martínez-Fernández, Verónica; Fernández-Pevida, Antonio; Cuevas-Bermúdez, Abel; Martín-Expósito, Manuel; Chávez, Sebastián; de la Cruz, Jesús; Navarro, Francisco

2014-01-01

Bud27, the yeast orthologue of human URI/RMP, is a member of the prefoldin-like family of ATP-independent molecular chaperones. It has recently been shown to mediate the assembly of the three RNA polymerases in an Rpb5-dependent manner. In this work, we present evidence of Bud27 modulating RNA pol II transcription elongation. We show that Bud27 associates with RNA pol II phosphorylated forms (CTD-Ser5P and CTD-Ser2P), and that its absence affects RNA pol II occupancy of transcribed genes. We also reveal that Bud27 associates in vivo with the Sth1 component of the chromatin remodeling complex RSC and mediates its association with RNA pol II. Our data suggest that Bud27, in addition of contributing to Rpb5 folding within the RNA polymerases, also participates in the correct assembly of other chromatin-associated protein complexes, such as RSC, thereby modulating their activity. PMID:25081216

Unconventional RNA-binding proteins: an uncharted zone in RNA biology.

PubMed

Albihlal, Waleed S; Gerber, André P

2018-06-16

RNA-binding proteins play essential roles in the post-transcriptional regulation of gene expression. While hundreds of RNA-binding proteins can be predicted computationally, the recent introduction of proteome-wide approaches has dramatically expanded the repertoire of proteins interacting with RNA. Besides canonical RNA-binding proteins that contain characteristic RNA-binding domains, many proteins that lack such domains but have other well-characterised cellular functions were identified; including metabolic enzymes, heat shock proteins, kinases, as well as transcription factors and chromatin-associated proteins. In the context of these recently published RNA-protein interactome datasets obtained from yeast, nematodes, flies, plants and mammalian cells, we discuss examples for seemingly evolutionary conserved "unconventional" RNA-binding proteins that act in central carbon metabolism, stress response or regulation of transcription. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Stimulation of Pol III-dependent 5S rRNA and U6 snRNA gene expression by AP-1 transcription factors.

PubMed

Ahuja, Richa; Kumar, Vijay

2017-07-01

RNA polymerase III transcribes structurally diverse group of essential noncoding RNAs including 5S ribosomal RNA (5SrRNA) and U6 snRNA. These noncoding RNAs are involved in RNA processing and ribosome biogenesis, thus, coupling Pol III activity to the rate of protein synthesis, cell growth, and proliferation. Even though a few Pol II-associated transcription factors have been reported to participate in Pol III-dependent transcription, its activation by activator protein 1 (AP-1) factors, c-Fos and c-Jun, has remained unexplored. Here, we show that c-Fos and c-Jun bind to specific sites in the regulatory regions of 5S rRNA (type I) and U6 snRNA (type III) gene promoters and stimulate their transcription. Our chromatin immunoprecipitation studies suggested that endogenous AP-1 factors bind to their cognate promoter elements during the G1/S transition of cell cycle apparently synchronous with Pol III transcriptional activity. Furthermore, the interaction of c-Jun with histone acetyltransferase p300 promoted the recruitment of p300/CBP complex on the promoters and facilitated the occupancy of Pol III transcriptional machinery via histone acetylation and chromatin remodeling. The findings of our study, together, suggest that AP-1 factors are novel regulators of Pol III-driven 5S rRNA and U6 snRNA expression with a potential role in cell proliferation. © 2017 Federation of European Biochemical Societies.

Extent, Causes, and Consequences of Small RNA Expression Variation in Human Adipose Tissue

PubMed Central

Knights, Andrew J.; Abreu-Goodger, Cei; van de Bunt, Martijn; Guerra-Assunção, José Afonso; Bartonicek, Nenad; van Dongen, Stijn; Mägi, Reedik; Nisbet, James; Barrett, Amy; Rantalainen, Mattias; Nica, Alexandra C.; Quail, Michael A.; Small, Kerrin S.; Glass, Daniel; Enright, Anton J.; Winn, John; Deloukas, Panos; Dermitzakis, Emmanouil T.; McCarthy, Mark I.; Spector, Timothy D.; Durbin, Richard; Lindgren, Cecilia M.

2012-01-01

Small RNAs are functional molecules that modulate mRNA transcripts and have been implicated in the aetiology of several common diseases. However, little is known about the extent of their variability within the human population. Here, we characterise the extent, causes, and effects of naturally occurring variation in expression and sequence of small RNAs from adipose tissue in relation to genotype, gene expression, and metabolic traits in the MuTHER reference cohort. We profiled the expression of 15 to 30 base pair RNA molecules in subcutaneous adipose tissue from 131 individuals using high-throughput sequencing, and quantified levels of 591 microRNAs and small nucleolar RNAs. We identified three genetic variants and three RNA editing events. Highly expressed small RNAs are more conserved within mammals than average, as are those with highly variable expression. We identified 14 genetic loci significantly associated with nearby small RNA expression levels, seven of which also regulate an mRNA transcript level in the same region. In addition, these loci are enriched for variants significant in genome-wide association studies for body mass index. Contrary to expectation, we found no evidence for negative correlation between expression level of a microRNA and its target mRNAs. Trunk fat mass, body mass index, and fasting insulin were associated with more than twenty small RNA expression levels each, while fasting glucose had no significant associations. This study highlights the similar genetic complexity and shared genetic control of small RNA and mRNA transcripts, and gives a quantitative picture of small RNA expression variation in the human population. PMID:22589741

Chronic nicotine treatment leads to induction of tyrosine hydroxylase in locus ceruleus neurons: the role of transcriptional activation.

PubMed

Sun, Baoyong; Chen, Xiqun; Xu, Lu; Sterling, Carol; Tank, A William

2004-10-01

Chronic nicotine treatment (two daily subcutaneous injections administered approximately 12 h apart for 14 days) is associated with long-term inductions of tyrosine hydroxylase (TH) protein and TH mRNA in locus ceruleus (LC) neurons. These increases persist for at least 3 days after the final nicotine injection in LC cell bodies and for at least 7 to 10 days in LC nerve terminal regions. We tested whether this long-term response is due to sustained stimulation of TH gene transcription rate. A semiquantitative reverse transcription-polymerase chain reaction assay was developed to assess changes in the levels of TH RNA primary transcripts; these changes are an indirect measurement of changes in TH gene transcription rate. TH RNA primary transcript levels increase rapidly in the LC after a single nicotine administration and return to basal levels by 24 h. A similar rapid and transient induction of LC TH RNA primary transcripts occurs after chronic nicotine administration. In contrast, TH RNA primary transcript levels remain elevated for a sustained period of time (at least 1 day) in the adrenal medulla after chronic nicotine administration. Similar rapid, but transient changes in LC TH RNA primary transcript levels are observed after repeated immobilization stress. These results suggest that TH gene transcription rate in the LC is stimulated rapidly after each nicotine injection; however, in contrast to the adrenal medulla, there is no sustained transcriptional response elicited by chronic nicotine treatment or repeated immobilization stress in the LC, suggesting that post-transcriptional mechanisms may also play a role in these long-term responses.

Cas9 gRNA engineering for genome editing, activation and repression

DOE PAGES

Kiani, Samira; Chavez, Alejandro; Tuttle, Marcelle; ...

2015-09-07

Here we demonstrate that by altering the length of Cas9-associated guide RNA(gRNA) we were able to control Cas9 nuclease activity and simultaneously perform genome editing and transcriptional regulation with a single Cas9 protein. We exploited these principles to engineer mammalian synthetic circuits with combined transcriptional regulation and kill functions governed by a single multifunctional Cas9 protein.

Coordination of genomic structure and transcription by the main bacterial nucleoid-associated protein HU

PubMed Central

Berger, Michael; Farcas, Anca; Geertz, Marcel; Zhelyazkova, Petya; Brix, Klaudia; Travers, Andrew; Muskhelishvili, Georgi

2010-01-01

The histone-like protein HU is a highly abundant DNA architectural protein that is involved in compacting the DNA of the bacterial nucleoid and in regulating the main DNA transactions, including gene transcription. However, the coordination of the genomic structure and function by HU is poorly understood. Here, we address this question by comparing transcript patterns and spatial distributions of RNA polymerase in Escherichia coli wild-type and hupA/B mutant cells. We demonstrate that, in mutant cells, upregulated genes are preferentially clustered in a large chromosomal domain comprising the ribosomal RNA operons organized on both sides of OriC. Furthermore, we show that, in parallel to this transcription asymmetry, mutant cells are also impaired in forming the transcription foci—spatially confined aggregations of RNA polymerase molecules transcribing strong ribosomal RNA operons. Our data thus implicate HU in coordinating the global genomic structure and function by regulating the spatial distribution of RNA polymerase in the nucleoid. PMID:20010798

Reverse Transcription Errors and RNA-DNA Differences at Short Tandem Repeats.

PubMed

Fungtammasan, Arkarachai; Tomaszkiewicz, Marta; Campos-Sánchez, Rebeca; Eckert, Kristin A; DeGiorgio, Michael; Makova, Kateryna D

2016-10-01

Transcript variation has important implications for organismal function in health and disease. Most transcriptome studies focus on assessing variation in gene expression levels and isoform representation. Variation at the level of transcript sequence is caused by RNA editing and transcription errors, and leads to nongenetically encoded transcript variants, or RNA-DNA differences (RDDs). Such variation has been understudied, in part because its detection is obscured by reverse transcription (RT) and sequencing errors. It has only been evaluated for intertranscript base substitution differences. Here, we investigated transcript sequence variation for short tandem repeats (STRs). We developed the first maximum-likelihood estimator (MLE) to infer RT error and RDD rates, taking next generation sequencing error rates into account. Using the MLE, we empirically evaluated RT error and RDD rates for STRs in a large-scale DNA and RNA replicated sequencing experiment conducted in a primate species. The RT error rates increased exponentially with STR length and were biased toward expansions. The RDD rates were approximately 1 order of magnitude lower than the RT error rates. The RT error rates estimated with the MLE from a primate data set were concordant with those estimated with an independent method, barcoded RNA sequencing, from a Caenorhabditis elegans data set. Our results have important implications for medical genomics, as STR allelic variation is associated with >40 diseases. STR nonallelic transcript variation can also contribute to disease phenotype. The MLE and empirical rates presented here can be used to evaluate the probability of disease-associated transcripts arising due to RDD. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Accurate RNA consensus sequencing for high-fidelity detection of transcriptional mutagenesis-induced epimutations.

PubMed

Reid-Bayliss, Kate S; Loeb, Lawrence A

2017-08-29

Transcriptional mutagenesis (TM) due to misincorporation during RNA transcription can result in mutant RNAs, or epimutations, that generate proteins with altered properties. TM has long been hypothesized to play a role in aging, cancer, and viral and bacterial evolution. However, inadequate methodologies have limited progress in elucidating a causal association. We present a high-throughput, highly accurate RNA sequencing method to measure epimutations with single-molecule sensitivity. Accurate RNA consensus sequencing (ARC-seq) uniquely combines RNA barcoding and generation of multiple cDNA copies per RNA molecule to eliminate errors introduced during cDNA synthesis, PCR, and sequencing. The stringency of ARC-seq can be scaled to accommodate the quality of input RNAs. We apply ARC-seq to directly assess transcriptome-wide epimutations resulting from RNA polymerase mutants and oxidative stress.

Post-transcriptional gene silencing triggered by sense transgenes involves uncapped antisense RNA and differs from silencing intentionally triggered by antisense transgenes.

PubMed

Parent, Jean-Sébastien; Jauvion, Vincent; Bouché, Nicolas; Béclin, Christophe; Hachet, Mélanie; Zytnicki, Matthias; Vaucheret, Hervé

2015-09-30

Although post-transcriptional gene silencing (PTGS) has been studied for more than a decade, there is still a gap in our understanding of how de novo silencing is initiated against genetic elements that are not supposed to produce double-stranded (ds)RNA. Given the pervasive transcription occurring throughout eukaryote genomes, we tested the hypothesis that unintended transcription could produce antisense (as)RNA molecules that participate to the initiation of PTGS triggered by sense transgenes (S-PTGS). Our results reveal a higher level of asRNA in Arabidopsis thaliana lines that spontaneously trigger S-PTGS than in lines that do not. However, PTGS triggered by antisense transgenes (AS-PTGS) differs from S-PTGS. In particular, a hypomorphic ago1 mutation that suppresses S-PTGS prevents the degradation of asRNA but not sense RNA during AS-PTGS, suggesting a different treatment of coding and non-coding RNA by AGO1, likely because of AGO1 association to polysomes. Moreover, the intended asRNA produced during AS-PTGS is capped whereas the asRNA produced during S-PTGS derives from 3' maturation of a read-through transcript and is uncapped. Thus, we propose that uncapped asRNA corresponds to the aberrant RNA molecule that is converted to dsRNA by RNA-DEPENDENT RNA POLYMERASE 6 in siRNA-bodies to initiate S-PTGS, whereas capped asRNA must anneal with sense RNA to produce dsRNA that initiate AS-PTGS. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Hepatotoxicity of high affinity gapmer antisense oligonucleotides is mediated by RNase H1 dependent promiscuous reduction of very long pre-mRNA transcripts

PubMed Central

Burel, Sebastien A.; Hart, Christopher E.; Cauntay, Patrick; Hsiao, Jill; Machemer, Todd; Katz, Melanie; Watt, Andy; Bui, Huynh-hoa; Younis, Husam; Sabripour, Mahyar; Freier, Susan M.; Hung, Gene; Dan, Amy; Prakash, T.P.; Seth, Punit P.; Swayze, Eric E.; Bennett, C. Frank; Crooke, Stanley T.; Henry, Scott P.

2016-01-01

High affinity antisense oligonucleotides (ASOs) containing bicylic modifications (BNA) such as locked nucleic acid (LNA) designed to induce target RNA cleavage have been shown to have enhanced potency along with a higher propensity to cause hepatotoxicity. In order to understand the mechanism of this hepatotoxicity, transcriptional profiles were collected from the livers of mice treated with a panel of highly efficacious hepatotoxic or non-hepatotoxic LNA ASOs. We observed highly selective transcript knockdown in mice treated with non-hepatotoxic LNA ASOs, while the levels of many unintended transcripts were reduced in mice treated with hepatotoxic LNA ASOs. This transcriptional signature was concurrent with on-target RNA reduction and preceded transaminitis. Remarkably, the mRNA transcripts commonly reduced by toxic LNA ASOs were generally not strongly associated with any particular biological process, cellular component or functional group. However, they tended to have much longer pre-mRNA transcripts. We also demonstrate that the off-target RNA knockdown and hepatotoxicity is attenuated by RNase H1 knockdown, and that this effect can be generalized to high affinity modifications beyond LNA. This suggests that for a certain set of ASOs containing high affinity modifications such as LNA, hepatotoxicity can occur as a result of unintended off-target RNase H1 dependent RNA degradation. PMID:26553810

Proteomic Analysis of Mitotic RNA Polymerase II Reveals Novel Interactors and Association With Proteins Dysfunctional in Disease*

PubMed Central

Möller, André; Xie, Sheila Q.; Hosp, Fabian; Lang, Benjamin; Phatnani, Hemali P.; James, Sonya; Ramirez, Francisco; Collin, Gayle B.; Naggert, Jürgen K.; Babu, M. Madan; Greenleaf, Arno L.; Selbach, Matthias; Pombo, Ana

2012-01-01

RNA polymerase II (RNAPII) transcribes protein-coding genes in eukaryotes and interacts with factors involved in chromatin remodeling, transcriptional activation, elongation, and RNA processing. Here, we present the isolation of native RNAPII complexes using mild extraction conditions and immunoaffinity purification. RNAPII complexes were extracted from mitotic cells, where they exist dissociated from chromatin. The proteomic content of native complexes in total and size-fractionated extracts was determined using highly sensitive LC-MS/MS. Protein associations with RNAPII were validated by high-resolution immunolocalization experiments in both mitotic cells and in interphase nuclei. Functional assays of transcriptional activity were performed after siRNA-mediated knockdown. We identify >400 RNAPII associated proteins in mitosis, among these previously uncharacterized proteins for which we show roles in transcriptional elongation. We also identify, as novel functional RNAPII interactors, two proteins involved in human disease, ALMS1 and TFG, emphasizing the importance of gene regulation for normal development and physiology. PMID:22199231

The RNA Exosome Syncs IAV-RNAPII Transcription to Promote Viral Ribogenesis and Infectivity.

PubMed

Rialdi, Alexander; Hultquist, Judd; Jimenez-Morales, David; Peralta, Zuleyma; Campisi, Laura; Fenouil, Romain; Moshkina, Natasha; Wang, Zhen Zhen; Laffleur, Brice; Kaake, Robyn M; McGregor, Michael J; Haas, Kelsey; Pefanis, Evangelos; Albrecht, Randy A; Pache, Lars; Chanda, Sumit; Jen, Joanna; Ochando, Jordi; Byun, Minji; Basu, Uttiya; García-Sastre, Adolfo; Krogan, Nevan; van Bakel, Harm; Marazzi, Ivan

2017-05-04

The nuclear RNA exosome is an essential multi-subunit complex that controls RNA homeostasis. Congenital mutations in RNA exosome genes are associated with neurodegenerative diseases. Little is known about the role of the RNA exosome in the cellular response to pathogens. Here, using NGS and human and mouse genetics, we show that influenza A virus (IAV) ribogenesis and growth are suppressed by impaired RNA exosome activity. Mechanistically, the nuclear RNA exosome coordinates the initial steps of viral transcription with RNAPII at host promoters. The viral polymerase complex co-opts the nuclear RNA exosome complex and cellular RNAs en route to 3' end degradation. Exosome deficiency uncouples chromatin targeting of the viral polymerase complex and the formation of cellular:viral RNA hybrids, which are essential RNA intermediates that license transcription of antisense genomic viral RNAs. Our results suggest that evolutionary arms races have shaped the cellular RNA quality control machinery. Copyright © 2017 Elsevier Inc. All rights reserved.

Oligomerization of the E. coli Core RNA Polymerase: Formation of (α2ββ'ω)2–DNA Complexes and Regulation of the Oligomerization by Auxiliary Subunits

PubMed Central

Kansara, Seema G.; Sukhodolets, Maxim V.

2011-01-01

In this work, using multiple, dissimilar physico-chemical techniques, we demonstrate that the Escherichia coli RNA polymerase core enzyme obtained through a classic purification procedure forms stable (α2ββ'ω)2 complexes in the presence or absence of short DNA probes. Multiple control experiments indicate that this self-association is unlikely to be mediated by RNA polymerase-associated non-protein molecules. We show that the formation of (α2ββ'ω)2 complexes is subject to regulation by known RNA polymerase interactors, such as the auxiliary SWI/SNF subunit of RNA polymerase RapA, as well as NusA and σ70. We also demonstrate that the separation of the core RNA polymerase and RNA polymerase holoenzyme species during Mono Q chromatography is likely due to oligomerization of the core enzyme. We have analyzed the oligomeric state of the polymerase in the presence or absence of DNA, an aspect that was missing from previous studies. Importantly, our work demonstrates that RNA polymerase oligomerization is compatible with DNA binding. Through in vitro transcription and in vivo experiments (utilizing a RapAR599/Q602 mutant lacking transcription-stimulatory function), we demonstrate that the formation of tandem (α2ββ'ω)2–DNA complexes is likely functionally significant and beneficial for the transcriptional activity of the polymerase. Taken together, our findings suggest a novel structural aspect of the E. coli elongation complex. We hypothesize that transcription by tandem RNA polymerase complexes initiated at hypothetical bidirectional “origins of transcription” may explain recurring switches of the direction of transcription in bacterial genomes. PMID:21533049

Global Transcriptional Start Site Mapping Using Differential RNA Sequencing Reveals Novel Antisense RNAs in Escherichia coli

PubMed Central

Thomason, Maureen K.; Bischler, Thorsten; Eisenbart, Sara K.; Förstner, Konrad U.; Zhang, Aixia; Herbig, Alexander; Nieselt, Kay

2014-01-01

While the model organism Escherichia coli has been the subject of intense study for decades, the full complement of its RNAs is only now being examined. Here we describe a survey of the E. coli transcriptome carried out using a differential RNA sequencing (dRNA-seq) approach, which can distinguish between primary and processed transcripts, and an automated prediction algorithm for transcriptional start sites (TSS). With the criterion of expression under at least one of three growth conditions examined, we predicted 14,868 TSS candidates, including 5,574 internal to annotated genes (iTSS) and 5,495 TSS corresponding to potential antisense RNAs (asRNAs). We examined expression of 14 candidate asRNAs by Northern analysis using RNA from wild-type E. coli and from strains defective for RNases III and E, two RNases reported to be involved in asRNA processing. Interestingly, nine asRNAs detected as distinct bands by Northern analysis were differentially affected by the rnc and rne mutations. We also compared our asRNA candidates with previously published asRNA annotations from RNA-seq data and discuss the challenges associated with these cross-comparisons. Our global transcriptional start site map represents a valuable resource for identification of transcription start sites, promoters, and novel transcripts in E. coli and is easily accessible, together with the cDNA coverage plots, in an online genome browser. PMID:25266388

The point of no return: The poly(A)-associated elongation checkpoint

PubMed Central

Tellier, Michael; Ferrer-Vicens, Ivan; Murphy, Shona

2016-01-01

abstract Cyclin-dependent kinases play critical roles in transcription by RNA polymerase II (pol II) and processing of the transcripts. For example, CDK9 regulates transcription of protein-coding genes, splicing, and 3′ end formation of the transcripts. Accordingly, CDK9 inhibitors have a drastic effect on the production of mRNA in human cells. Recent analyses indicate that CDK9 regulates transcription at the early-elongation checkpoint of the vast majority of pol II-transcribed genes. Our recent discovery of an additional CDK9-regulated elongation checkpoint close to poly(A) sites adds a new layer to the control of transcription by this critical cellular kinase. This novel poly(A)-associated checkpoint has the potential to powerfully regulate gene expression just before a functional polyadenylated mRNA is produced: the point of no return. However, many questions remain to be answered before the role of this checkpoint becomes clear. Here we speculate on the possible biological significance of this novel mechanism of gene regulation and the players that may be involved. PMID:26853452

Coordination of m6A mRNA methylation and gene transcription by ZFP217 regulates pluripotency and reprogramming

PubMed Central

Aguilo, Francesca; Zhang, Fan; Sancho, Ana; Fidalgo, Miguel; Di Cecilia, Serena; Vashisht, Ajay; Lee, Dung-Fang; Chen, Chih-Hung; Rengasamy, Madhumitha; Andino, Blanca; Jahouh, Farid; Roman, Angel; Krig, Sheryl R.; Wang, Rong; Zhang, Weijia; Wohlschlegel, James A.; Wang, Jianlong; Walsh, Martin J.

2015-01-01

SUMMARY Epigenetic and epitranscriptomic networks have important functions in maintaining pluripotency of embryonic stem cells (ESCs) and somatic cell reprogramming. However the mechanisms integrating the actions of these distinct networks are only partially understood. Here, we show that the chromatin-associated zinc finger protein 217 (ZFP217) coordinates epigenetic and epitranscriptomic regulation. ZFP217 interacts with several epigenetic regulators, activates transcription of key pluripotency genes, and modulates N6-methyladenosine (m6A) deposition on their transcripts by sequestering the enzyme m6A methyltransferase-like 3 (METTL3). Consistently, Zfp217 depletion compromises ESC self-renewal and somatic cell reprogramming, globally increases m6A RNA levels, and enhances m6A modification of Nanog, Sox2, Klf4, and c-Myc mRNAs, promoting their degradation. ZFP217 binds its own target gene mRNAs, which are also METTL3-associated, and is enriched at promoters of m6A-modified transcripts. Collectively, these findings shed light on how a transcription factor can tightly couple gene transcription to m6A RNA modification to insure ESC identity. PMID:26526723

MiRNA-Target Interaction Reveals Cell-Specific Post-Transcriptional Regulation in Mammalian Cell Lines

PubMed Central

Kulkarni, Varun; Naqvi, Afsar Raza; Uttamani, Juhi Raju; Nares, Salvador

2016-01-01

MicroRNAs are 18–22 nucleotides long, non-coding RNAs that bind transcripts with complementary sequences leading to either mRNA degradation or translational suppression. However, the inherent differences in preferred mode of miRNA regulation among cells of different origin have not been examined. In our previous transcriptome profiling studies, we observed that post-transcriptional regulation can differ substantially depending on the cell in context. Here we examined mechanistic differences in the regulation of a let-7a targeted (wild type) or resistant (mutant) engineered renilla transcript across various mammalian cell lines of diverse origin. Dual luciferase assays show that compared to mutant (mut), the reporter gene containing wild type (wt) let-7a binding sites was efficiently suppressed upon transfection in various cell lines. Importantly, the strength of miRNA regulation varied across the cell lines. Total RNA analysis demonstrates that wt renilla mRNA was expressed to similar or higher levels compared to mut suggesting that translation repression is a predominant mode of miRNA regulation. Nonetheless, transcript degradation was observed in some cell lines. Ago-2 immunoprecipitation show that miRNA repressed renilla mRNA are associated with functional mi-RISC (miRNA-RNA induced silencing complex). Given the immense potential of miRNA as a therapeutic option, these findings highlight the necessity to thoroughly examine the mode of mRNA regulation in order to achieve the beneficial effects in targeting cells. PMID:26761000

Milk: an epigenetic amplifier of FTO-mediated transcription? Implications for Western diseases.

PubMed

Melnik, Bodo C

2015-12-21

Single-nucleotide polymorphisms within intron 1 of the FTO (fat mass and obesity-associated) gene are associated with enhanced FTO expression, increased body weight, obesity and type 2 diabetes mellitus (T2DM). The N (6) -methyladenosine (m(6)A) demethylase FTO plays a pivotal regulatory role for postnatal growth and energy expenditure. The purpose of this review is to provide translational evidence that links milk signaling with FTO-activated transcription of the milk recipient. FTO-dependent demethylation of m(6)A regulates mRNA splicing required for adipogenesis, increases the stability of mRNAs, and affects microRNA (miRNA) expression and miRNA biosynthesis. FTO senses branched-chain amino acids (BCAAs) and activates the nutrient sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1), which plays a key role in translation. Milk provides abundant BCAAs and glutamine, critical components increasing FTO expression. CpG hypomethylation in the first intron of FTO has recently been associated with T2DM. CpG methylation is generally associated with gene silencing. In contrast, CpG demethylation generally increases transcription. DNA de novo methylation of CpG sites is facilitated by DNA methyltransferases (DNMT) 3A and 3B, whereas DNA maintenance methylation is controlled by DNMT1. MiRNA-29s target all DNMTs and thus reduce DNA CpG methylation. Cow´s milk provides substantial amounts of exosomal miRNA-29s that reach the systemic circulation and target mRNAs of the milk recipient. Via DNMT suppression, milk exosomal miRNA-29s may reduce the magnitude of FTO methylation, thereby epigenetically increasing FTO expression in the milk consumer. High lactation performance with increased milk yield has recently been associated with excessive miRNA-29 expression of dairy cow mammary epithelial cells (DCMECs). Notably, the galactopoietic hormone prolactin upregulates the transcription factor STAT3, which induces miRNA-29 expression. In a retrovirus-like manner milk exosomes may transfer DCMEC-derived miRNA-29s and bovine FTO mRNA to the milk consumer amplifying FTO expression. There is compelling evidence that obesity, T2DM, prostate and breast cancer, and neurodegenerative diseases are all associated with increased FTO expression. Maximization of lactation performance by veterinary medicine with enhanced miRNA-29s and FTO expression associated with increased exosomal miRNA-29 and FTO mRNA transfer to the milk consumer may represent key epigenetic mechanisms promoting FTO/mTORC1-mediated diseases of civilization.

Long non-coding RNA and Polycomb: an intricate partnership in cancer biology.

PubMed

Achour, Cyrinne; Aguilo, Francesca

2018-06-01

High-throughput analyses have revealed that the vast majority of the transcriptome does not code for proteins. These non-translated transcripts, when larger than 200 nucleotides, are termed long non-coding RNAs (lncRNAs), and play fundamental roles in diverse cellular processes. LncRNAs are subject to dynamic chemical modification, adding another layer of complexity to our understanding of the potential roles that lncRNAs play in health and disease. Many lncRNAs regulate transcriptional programs by influencing the epigenetic state through direct interactions with chromatin-modifying proteins. Among these proteins, Polycomb repressive complexes 1 and 2 (PRC1 and PRC2) have been shown to be recruited by lncRNAs to silence target genes. Aberrant expression, deficiency or mutation of both lncRNA and Polycomb have been associated with numerous human diseases, including cancer. In this review, we have highlighted recent findings regarding the concerted mechanism of action of Polycomb group proteins (PcG), acting together with some classically defined lncRNAs including X-inactive specific transcript ( XIST ), antisense non-coding RNA in the INK4 locus ( ANRIL ), metastasis associated lung adenocarcinoma transcript 1 ( MALAT1 ), and HOX transcript antisense RNA ( HOTAIR ).

Characterization of herpes simplex virus 2 primary microRNA Transcript regulation.

PubMed

Tang, Shuang; Bosch-Marce, Marta; Patel, Amita; Margolis, Todd P; Krause, Philip R

2015-05-01

In order to understand factors that may influence latency-associated transcription and latency-associated transcript (LAT) phenotypes, we studied the expression of the herpes simplex virus 2 (HSV-2) LAT-associated microRNAs (miRNAs). We mapped the transcription initiation sites of all three primary miRNA transcripts and identified the ICP4-binding sequences at the transcription initiation sites of both HSV-2 LAT (pri-miRNA for miR-I and miR-II, which target ICP34.5, and miR-III, which targets ICP0) and L/ST (a pri-miRNA for miR-I and miR-II) but not at that of the primary miR-H6 (for which the target is unknown). We confirmed activity of the putative HSV-2 L/ST promoter and found that ICP4 trans-activates the L/ST promoter when the ICP4-binding site at its transcription initiation site is mutated, suggesting that ICP4 may play a dual role in regulating transcription of L/ST and, consequently, of miR-I and miR-II. LAT exon 1 (containing LAT enhancer sequences), together with the LAT promoter region, comprises a bidirectional promoter required for the expression of both LAT-encoded miRNAs and miR-H6 in latently infected mouse ganglia. The ability of ICP4 to suppress ICP34.5-targeting miRNAs and to activate lytic viral genes suggests that ICP4 could play a key role in the switch between latency and reactivation. The HSV-2 LAT and viral miRNAs expressed in the LAT region are the most abundant viral transcripts during HSV latency. The balance between the expression of LAT and LAT-associated miRNAs and the expression of lytic viral transcripts from the opposite strand appears to influence whether individual HSV-infected neurons will be latently or productively infected. The outcome of neuronal infection may thus depend on regulation of gene expression of the corresponding primary miRNAs. In the present study, we characterize promoter sequences responsible for miRNA expression, including identification of the primary miRNA 5' ends and evaluation of ICP4 response. These findings provide further insight into the virus' strategy to tightly control expression of lytic cycle genes (especially the neurovirulence factor, ICP34.5) and suggest a mechanism (via ICP4) for the transition from latency to reactivated productive infection. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Characterization of Herpes Simplex Virus 2 Primary MicroRNA Transcript Regulation

PubMed Central

Bosch-Marce, Marta; Patel, Amita; Margolis, Todd P.

2015-01-01

ABSTRACT In order to understand factors that may influence latency-associated transcription and latency-associated transcript (LAT) phenotypes, we studied the expression of the herpes simplex virus 2 (HSV-2) LAT-associated microRNAs (miRNAs). We mapped the transcription initiation sites of all three primary miRNA transcripts and identified the ICP4-binding sequences at the transcription initiation sites of both HSV-2 LAT (pri-miRNA for miR-I and miR-II, which target ICP34.5, and miR-III, which targets ICP0) and L/ST (a pri-miRNA for miR-I and miR-II) but not at that of the primary miR-H6 (for which the target is unknown). We confirmed activity of the putative HSV-2 L/ST promoter and found that ICP4 trans-activates the L/ST promoter when the ICP4-binding site at its transcription initiation site is mutated, suggesting that ICP4 may play a dual role in regulating transcription of L/ST and, consequently, of miR-I and miR-II. LAT exon 1 (containing LAT enhancer sequences), together with the LAT promoter region, comprises a bidirectional promoter required for the expression of both LAT-encoded miRNAs and miR-H6 in latently infected mouse ganglia. The ability of ICP4 to suppress ICP34.5-targeting miRNAs and to activate lytic viral genes suggests that ICP4 could play a key role in the switch between latency and reactivation. IMPORTANCE The HSV-2 LAT and viral miRNAs expressed in the LAT region are the most abundant viral transcripts during HSV latency. The balance between the expression of LAT and LAT-associated miRNAs and the expression of lytic viral transcripts from the opposite strand appears to influence whether individual HSV-infected neurons will be latently or productively infected. The outcome of neuronal infection may thus depend on regulation of gene expression of the corresponding primary miRNAs. In the present study, we characterize promoter sequences responsible for miRNA expression, including identification of the primary miRNA 5′ ends and evaluation of ICP4 response. These findings provide further insight into the virus' strategy to tightly control expression of lytic cycle genes (especially the neurovirulence factor, ICP34.5) and suggest a mechanism (via ICP4) for the transition from latency to reactivated productive infection. PMID:25673716

Acetyl Coenzyme A Stimulates RNA Polymerase II Transcription and Promoter Binding by Transcription Factor IID in the Absence of Histones

PubMed Central

Galasinski, Shelly K.; Lively, Tricia N.; Grebe de Barron, Alexandra; Goodrich, James A.

2000-01-01

Protein acetylation has emerged as a means of controlling levels of mRNA synthesis in eukaryotic cells. Here we report that acetyl coenzyme A (acetyl-CoA) stimulates RNA polymerase II transcription in vitro in the absence of histones. The effect of acetyl-CoA on basal and activated transcription was studied in a human RNA polymerase II transcription system reconstituted from recombinant and highly purified transcription factors. Both basal and activated transcription were stimulated by the addition of acetyl-CoA to transcription reaction mixtures. By varying the concentrations of general transcription factors in the reaction mixtures, we found that acetyl-CoA decreased the concentration of TFIID required to observe transcription. Electrophoretic mobility shift assays and DNase I footprinting revealed that acetyl-CoA increased the affinity of the general transcription factor TFIID for promoter DNA in a TBP-associated factor (TAF)-dependent manner. Interestingly, acetyl-CoA also caused a conformational change in the TFIID-TFIIA-promoter complex as assessed by DNase I footprinting. These results show that acetyl-CoA alters the DNA binding activity of TFIID and indicate that this biologically important cofactor functions at multiple levels to control gene expression. PMID:10688640

Acetyl coenzyme A stimulates RNA polymerase II transcription and promoter binding by transcription factor IID in the absence of histones.

PubMed

Galasinski, S K; Lively, T N; Grebe De Barron, A; Goodrich, J A

2000-03-01

Protein acetylation has emerged as a means of controlling levels of mRNA synthesis in eukaryotic cells. Here we report that acetyl coenzyme A (acetyl-CoA) stimulates RNA polymerase II transcription in vitro in the absence of histones. The effect of acetyl-CoA on basal and activated transcription was studied in a human RNA polymerase II transcription system reconstituted from recombinant and highly purified transcription factors. Both basal and activated transcription were stimulated by the addition of acetyl-CoA to transcription reaction mixtures. By varying the concentrations of general transcription factors in the reaction mixtures, we found that acetyl-CoA decreased the concentration of TFIID required to observe transcription. Electrophoretic mobility shift assays and DNase I footprinting revealed that acetyl-CoA increased the affinity of the general transcription factor TFIID for promoter DNA in a TBP-associated factor (TAF)-dependent manner. Interestingly, acetyl-CoA also caused a conformational change in the TFIID-TFIIA-promoter complex as assessed by DNase I footprinting. These results show that acetyl-CoA alters the DNA binding activity of TFIID and indicate that this biologically important cofactor functions at multiple levels to control gene expression.

Radiation-induced alternative transcripts as detected in total and polysome-bound mRNA.

PubMed

Wahba, Amy; Ryan, Michael C; Shankavaram, Uma T; Camphausen, Kevin; Tofilon, Philip J

2018-01-02

Alternative splicing is a critical event in the posttranscriptional regulation of gene expression. To investigate whether this process influences radiation-induced gene expression we defined the effects of ionizing radiation on the generation of alternative transcripts in total cellular mRNA (the transcriptome) and polysome-bound mRNA (the translatome) of the human glioblastoma stem-like cell line NSC11. For these studies, RNA-Seq profiles from control and irradiated cells were compared using the program SpliceSeq to identify transcripts and splice variations induced by radiation. As compared to the transcriptome (total RNA) of untreated cells, the radiation-induced transcriptome contained 92 splice events suggesting that radiation induced alternative splicing. As compared to the translatome (polysome-bound RNA) of untreated cells, the radiation-induced translatome contained 280 splice events of which only 24 were overlapping with the radiation-induced transcriptome. These results suggest that radiation not only modifies alternative splicing of precursor mRNA, but also results in the selective association of existing mRNA isoforms with polysomes. Comparison of radiation-induced alternative transcripts to radiation-induced gene expression in total RNA revealed little overlap (about 3%). In contrast, in the radiation-induced translatome, about 38% of the induced alternative transcripts corresponded to genes whose expression level was affected in the translatome. This study suggests that whereas radiation induces alternate splicing, the alternative transcripts present at the time of irradiation may play a role in the radiation-induced translational control of gene expression and thus cellular radioresponse.

A conformational switch is responsible for the reversal of the 6S RNA-dependent RNA polymerase inhibition in Escherichia coli.

PubMed

Steuten, Benedikt; Wagner, Rolf

2012-12-01

6S RNA is a bacterial transcriptional regulator,which accumulates during stationary phase and inhibits transcription from many promoters due to stable association with σ 70 -containing RNA polymerase. This inhibitory RNA polymerase ∼ 6S RNA complex dissociates during nutritional upshift, when cells undergo outgrowth from stationary phase, releasing active RNA polymerase ready for transcription. The release reaction depends on a characteristic property of 6S RNAs, namely to act as template for the de novo synthesis of small RNAs, termed pRNAs.Here, we used limited hydrolysis with structure-specific RNases and in-line probing of isolated 6S RNA and 6SRNA ∼ pRNA complexes to investigate the molecular details leading to the release reaction. Our results indicate that pRNA transcription induces the refolding of the 6S RNA secondary structure by disrupting part of the closing stem(conserved sequence regions CRI and CRIV) and formation of a new hairpin (conserved sequence regions CRIII and CRIV). Comparison of the dimethylsulfate modification pattern of 6S RNA in living cells at stationary growth and during outgrowth confirmed the conformational change observed in vitro. Based on our results, a model describing the individual steps of the release reaction is presented.

Defining Transcriptional Regulatory Mechanisms for Primary let-7 miRNAs

PubMed Central

Gaeta, Xavier; Le, Luat; Lin, Ying; Xie, Yuan; Lowry, William E.

2017-01-01

The let-7 family of miRNAs have been shown to control developmental timing in organisms from C. elegans to humans; their function in several essential cell processes throughout development is also well conserved. Numerous studies have defined several steps of post-transcriptional regulation of let-7 production; from pri-miRNA through pre-miRNA, to the mature miRNA that targets endogenous mRNAs for degradation or translational inhibition. Less-well defined are modes of transcriptional regulation of the pri-miRNAs for let-7. let-7 pri-miRNAs are expressed in polycistronic fashion, in long transcripts newly annotated based on chromatin-associated RNA-sequencing. Upon differentiation, we found that some let-7 pri-miRNAs are regulated at the transcriptional level, while others appear to be constitutively transcribed. Using the Epigenetic Roadmap database, we further annotated regulatory elements of each polycistron identified putative promoters and enhancers. Probing these regulatory elements for transcription factor binding sites identified factors that regulate transcription of let-7 in both promoter and enhancer regions, and identified novel regulatory mechanisms for this important class of miRNAs. PMID:28052101

Alteration of BRCA1 expression affects alcohol-induced transcription of RNA Pol III-dependent genes.

PubMed

Zhong, Qian; Shi, Ganggang; Zhang, Yanmei; Lu, Lei; Levy, Daniel; Zhong, Shuping

2015-02-01

Emerging evidence has indicated that alcohol consumption is an established risk factor for breast cancer. Deregulation of RNA polymerase III (Pol III) transcription enhances cellular Pol III gene production, leading to an increase in translational capacity to promote cell transformation and tumor formation. We have reported that alcohol intake increases Pol III gene transcription to promote cell transformation and tumor formation in vitro and in vivo. Studies revealed that tumor suppressors, pRb, p53, PTEN and Maf1 repress the transcription of Pol III genes. BRCA1 is a tumor suppressor and its mutation is tightly related to breast cancer development. However, it is not clear whether BRCA1 expression affects alcohol-induced transcription of Pol III genes. At the present studies, we report that restoring BRCA1 in HCC 1937 cells, which is a BRCA1 deficient cell line, represses Pol III gene transcription. Expressing mutant or truncated BRCA1 in these cells does not affect the ability of repression on Pol III genes. Our analysis has demonstrated that alcohol induces Pol III gene transcription. More importantly, overexpression of BRCA1 in estrogen receptor positive (ER+) breast cancer cells (MCF-7) decreases the induction of tRNA(Leu) and 5S rRNA genes by alcohol, whereas reduction of BRCA1 by its siRNA slightly increases the transcription of the class of genes. This suggests that BRCA1 is associated with alcohol-induced deregulation of Pol III genes. These studies for the first time demonstrate the role of BRCA1 in induction of Pol III genes by alcohol and uncover a novel mechanism of alcohol-associated breast cancer. Copyright © 2014 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiani, Samira; Chavez, Alejandro; Tuttle, Marcelle

Here we demonstrate that by altering the length of Cas9-associated guide RNA(gRNA) we were able to control Cas9 nuclease activity and simultaneously perform genome editing and transcriptional regulation with a single Cas9 protein. We exploited these principles to engineer mammalian synthetic circuits with combined transcriptional regulation and kill functions governed by a single multifunctional Cas9 protein.

Neuregulin 1 transcripts are differentially expressed in schizophrenia and regulated by 5′ SNPs associated with the disease

PubMed Central

Law, Amanda J.; Lipska, Barbara K.; Weickert, Cynthia Shannon; Hyde, Thomas M.; Straub, Richard E.; Hashimoto, Ryota; Harrison, Paul J.; Kleinman, Joel E.; Weinberger, Daniel R.

2006-01-01

Genetic variation in neuregulin 1 (NRG1) is associated with schizophrenia. The disease-associated SNPs are noncoding, and their functional implications remain unknown. We hypothesized that differential expression of the NRG1 gene explains its association to the disease. We examined four of the disease-associated SNPs that make up the original risk haplotype in the 5′ upstream region of the gene for their effects on mRNA abundance of NRG1 types I–IV in human postmortem hippocampus. Diagnostic comparisons revealed a 34% increase in type I mRNA in schizophrenia and an interaction of diagnosis and genotype (SNP8NRG221132) on this transcript. Of potentially greater interest, a single SNP within the risk haplotype (SNP8NRG243177) and a 22-kb block of this core haplotype are associated with mRNA expression for the novel type IV isoform in patients and controls. Bioinformatic promoter analyses indicate that both SNPs lead to a gain/loss of putative binding sites for three transcription factors, serum response factor, myelin transcription factor-1, and High Mobility Group Box Protein-1. These data implicate variation in isoform expression as a molecular mechanism for the genetic association of NRG1 with schizophrenia. PMID:16618933

The yeast prefoldin-like URI-orthologue Bud27 associates with the RSC nucleosome remodeler and modulates transcription.

PubMed

Mirón-García, María Carmen; Garrido-Godino, Ana Isabel; Martínez-Fernández, Verónica; Fernández-Pevida, Antonio; Cuevas-Bermúdez, Abel; Martín-Expósito, Manuel; Chávez, Sebastián; de la Cruz, Jesús; Navarro, Francisco

2014-09-01

Bud27, the yeast orthologue of human URI/RMP, is a member of the prefoldin-like family of ATP-independent molecular chaperones. It has recently been shown to mediate the assembly of the three RNA polymerases in an Rpb5-dependent manner. In this work, we present evidence of Bud27 modulating RNA pol II transcription elongation. We show that Bud27 associates with RNA pol II phosphorylated forms (CTD-Ser5P and CTD-Ser2P), and that its absence affects RNA pol II occupancy of transcribed genes. We also reveal that Bud27 associates in vivo with the Sth1 component of the chromatin remodeling complex RSC and mediates its association with RNA pol II. Our data suggest that Bud27, in addition of contributing to Rpb5 folding within the RNA polymerases, also participates in the correct assembly of other chromatin-associated protein complexes, such as RSC, thereby modulating their activity. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

The RNA synthesis machinery of negative-stranded RNA viruses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortín, Juan, E-mail: jortin@cnb.csic.es; Martín-Benito, Jaime, E-mail: jmartinb@cnb.csic.es

The group of Negative-Stranded RNA Viruses (NSVs) includes many human pathogens, like the influenza, measles, mumps, respiratory syncytial or Ebola viruses, which produce frequent epidemics of disease and occasional, high mortality outbreaks by transmission from animal reservoirs. The genome of NSVs consists of one to several single-stranded, negative-polarity RNA molecules that are always assembled into mega Dalton-sized complexes by association to many nucleoprotein monomers. These RNA-protein complexes or ribonucleoproteins function as templates for transcription and replication by action of the viral RNA polymerase and accessory proteins. Here we review our knowledge on these large RNA-synthesis machines, including the structure ofmore » their components, the interactions among them and their enzymatic activities, and we discuss models showing how they perform the virus transcription and replication programmes. - Highlights: • Overall organisation of NSV RNA synthesis machines. • Structure and function of the ribonucleoprotein components: Atomic structure of the RNA polymerase complex. • Commonalities and differences between segmented- and non-segmented NSVs. • Transcription versus replication programmes.« less

Histone H3K36 methylation regulates pre-mRNA splicing in Saccharomyces cerevisiae

PubMed Central

Sorenson, Matthew R.; Jha, Deepak K.; Ucles, Stefanie A.; Flood, Danielle M.; Strahl, Brian D.; Stevens, Scott W.; Kress, Tracy L.

2016-01-01

ABSTRACT Co-transcriptional splicing takes place in the context of a highly dynamic chromatin architecture, yet the role of chromatin restructuring in coordinating transcription with RNA splicing has not been fully resolved. To further define the contribution of histone modifications to pre-mRNA splicing in Saccharomyces cerevisiae, we probed a library of histone point mutants using a reporter to monitor pre-mRNA splicing. We found that mutation of H3 lysine 36 (H3K36) – a residue methylated by Set2 during transcription elongation – exhibited phenotypes similar to those of pre-mRNA splicing mutants. We identified genetic interactions between genes encoding RNA splicing factors and genes encoding the H3K36 methyltransferase Set2 and the demethylase Jhd1 as well as point mutations of H3K36 that block methylation. Consistent with the genetic interactions, deletion of SET2, mutations modifying the catalytic activity of Set2 or H3K36 point mutations significantly altered expression of our reporter and reduced splicing of endogenous introns. These effects were dependent on the association of Set2 with RNA polymerase II and H3K36 dimethylation. Additionally, we found that deletion of SET2 reduces the association of the U2 and U5 snRNPs with chromatin. Thus, our study provides the first evidence that H3K36 methylation plays a role in co-transcriptional RNA splicing in yeast. PMID:26821844

Profilin Is Required for Optimal Actin-Dependent Transcription of Respiratory Syncytial Virus Genome RNA

PubMed Central

Burke, Emily; Mahoney, Nicole M.; Almo, Steven C.; Barik, Sailen

2000-01-01

Transcription of human respiratory syncytial virus (RSV) genome RNA exhibited an obligatory need for the host cytoskeletal protein actin. Optimal transcription, however, required the participation of another cellular protein that was characterized as profilin by a number of criteria. The amino acid sequence of the protein, purified on the basis of its transcription-optimizing activity in vitro, exactly matched that of profilin. RSV transcription was inhibited 60 to 80% by antiprofilin antibody or poly-l-proline, molecules that specifically bind profilin. Native profilin, purified from extracts of lung epithelial cells by affinity binding to a poly-l-proline matrix, stimulated the actin-saturated RSV transcription by 2.5- to 3-fold. Recombinant profilin, expressed in bacteria, stimulated viral transcription as effectively as the native protein and was also inhibited by poly-l-proline. Profilin alone, in the absence of actin, did not activate viral transcription. It is estimated that at optimal levels of transcription, every molecule of viral genomic RNA associates with approximately the following number of protein molecules: 30 molecules of L, 120 molecules of phosphoprotein P, and 60 molecules each of actin and profilin. Together, these results demonstrated for the first time a cardinal role for profilin, an actin-modulatory protein, in the transcription of a paramyxovirus RNA genome. PMID:10623728

TIF-IC, a factor involved in both transcription initiation and elongation of RNA polymerase I.

PubMed

Schnapp, G; Schnapp, A; Rosenbauer, H; Grummt, I

1994-09-01

We have characterized a transcription factor from Ehrlich ascites cells that is required for ribosomal gene transcription by RNA polymerase I (Pol I). This factor, termed TIF-IC, has a native molecular mass of 65 kDa, associates with Pol I, and is required both for the assembly of Sarkosyl-resistant initiation complexes and for the formation of the first internucleotide bonds. In addition to its function in transcription initiation, TIF-IC also plays a role in elongation of nascent RNA chains. At suboptimal levels of TIF-IC, transcripts with heterogeneous 3' ends are formed which are chased into full-length transcripts by the addition of more TIF-IC. Moreover, on a tailed template, which allows initiation in the absence of auxiliary factors, TIF-IC was found to stimulate the overall rate of transcription elongation and suppress pausing of Pol I. Thus TIF-IC appears to serve a function similar to the Pol II-specific factor TFIIF which is required for Pol II transcription initiation and elongation.

A Novel RNA Polymerase I Transcription Initiation Factor, TIF-IE, Commits rRNA Genes by Interaction with TIF-IB, Not by DNA Binding

PubMed Central

Al-Khouri, Anna Maria; Paule, Marvin R.

2002-01-01

In the small, free-living amoeba Acanthamoeba castellanii, rRNA transcription requires, in addition to RNA polymerase I, a single DNA-binding factor, transcription initiation factor IB (TIF-IB). TIF-IB is a multimeric protein that contains TATA-binding protein (TBP) and four TBP-associated factors that are specific for polymerase I transcription. TIF-IB is required for accurate and promoter-specific initiation of rRNA transcription, recruiting and positioning the polymerase on the start site by protein-protein interaction. In A. castellanii, partially purified TIF-IB can form a persistent complex with the ribosomal DNA (rDNA) promoter while homogeneous TIF-IB cannot. An additional factor, TIF-IE, is required along with homogeneous TIF-IB for the formation of a stable complex on the rDNA core promoter. We show that TIF-IE by itself, however, does not bind to the rDNA promoter and thus differs in its mechanism from the upstream binding factor and upstream activating factor, which carry out similar complex-stabilizing functions in vertebrates and yeast, respectively. In addition to its presence in impure TIF-IB, TIF-IE is found in highly purified fractions of polymerase I, with which it associates. Renaturation of polypeptides excised from sodium dodecyl sulfate-polyacrylamide gels showed that a 141-kDa polypeptide possesses all the known activities of TIF-IE. PMID:11784852

A novel RNA polymerase I transcription initiation factor, TIF-IE, commits rRNA genes by interaction with TIF-IB, not by DNA binding.

PubMed

Al-Khouri, Anna Maria; Paule, Marvin R

2002-02-01

In the small, free-living amoeba Acanthamoeba castellanii, rRNA transcription requires, in addition to RNA polymerase I, a single DNA-binding factor, transcription initiation factor IB (TIF-IB). TIF-IB is a multimeric protein that contains TATA-binding protein (TBP) and four TBP-associated factors that are specific for polymerase I transcription. TIF-IB is required for accurate and promoter-specific initiation of rRNA transcription, recruiting and positioning the polymerase on the start site by protein-protein interaction. In A. castellanii, partially purified TIF-IB can form a persistent complex with the ribosomal DNA (rDNA) promoter while homogeneous TIF-IB cannot. An additional factor, TIF-IE, is required along with homogeneous TIF-IB for the formation of a stable complex on the rDNA core promoter. We show that TIF-IE by itself, however, does not bind to the rDNA promoter and thus differs in its mechanism from the upstream binding factor and upstream activating factor, which carry out similar complex-stabilizing functions in vertebrates and yeast, respectively. In addition to its presence in impure TIF-IB, TIF-IE is found in highly purified fractions of polymerase I, with which it associates. Renaturation of polypeptides excised from sodium dodecyl sulfate-polyacrylamide gels showed that a 141-kDa polypeptide possesses all the known activities of TIF-IE.

Genome-Wide RNA Polymerase II Profiles and RNA Accumulation Reveal Kinetics of Transcription and Associated Epigenetic Changes During Diurnal Cycles

PubMed Central

Gilardi, Federica; Liechti, Robin; Martin, Olivier; Harshman, Keith; Delorenzi, Mauro; Desvergne, Béatrice; Herr, Winship; Deplancke, Bart; Schibler, Ueli; Rougemont, Jacques; Guex, Nicolas; Hernandez, Nouria; Naef, Felix

2012-01-01

Interactions of cell-autonomous circadian oscillators with diurnal cycles govern the temporal compartmentalization of cell physiology in mammals. To understand the transcriptional and epigenetic basis of diurnal rhythms in mouse liver genome-wide, we generated temporal DNA occupancy profiles by RNA polymerase II (Pol II) as well as profiles of the histone modifications H3K4me3 and H3K36me3. We used these data to quantify the relationships of phases and amplitudes between different marks. We found that rhythmic Pol II recruitment at promoters rather than rhythmic transition from paused to productive elongation underlies diurnal gene transcription, a conclusion further supported by modeling. Moreover, Pol II occupancy preceded mRNA accumulation by 3 hours, consistent with mRNA half-lives. Both methylation marks showed that the epigenetic landscape is highly dynamic and globally remodeled during the 24-hour cycle. While promoters of transcribed genes had tri-methylated H3K4 even at their trough activity times, tri-methylation levels reached their peak, on average, 1 hour after Pol II. Meanwhile, rhythms in tri-methylation of H3K36 lagged transcription by 3 hours. Finally, modeling profiles of Pol II occupancy and mRNA accumulation identified three classes of genes: one showing rhythmicity both in transcriptional and mRNA accumulation, a second class with rhythmic transcription but flat mRNA levels, and a third with constant transcription but rhythmic mRNAs. The latter class emphasizes widespread temporally gated posttranscriptional regulation in the mouse liver. PMID:23209382

CLL Cells Respond to B-Cell Receptor Stimulation with a MicroRNA/mRNA Signature Associated with MYC Activation and Cell Cycle Progression

PubMed Central

Pede, Valerie; Rombout, Ans; Vermeire, Jolien; Naessens, Evelien; Mestdagh, Pieter; Robberecht, Nore; Vanderstraeten, Hanne; Van Roy, Nadine; Vandesompele, Jo; Speleman, Frank; Philippé, Jan; Verhasselt, Bruno

2013-01-01

Chronic lymphocytic leukemia (CLL) is a disease with variable clinical outcome. Several prognostic factors such as the immunoglobulin heavy chain variable genes (IGHV) mutation status are linked to the B-cell receptor (BCR) complex, supporting a role for triggering the BCR in vivo in the pathogenesis. The miRNA profile upon stimulation and correlation with IGHV mutation status is however unknown. To evaluate the transcriptional response of peripheral blood CLL cells upon BCR stimulation in vitro, miRNA and mRNA expression was measured using hybridization arrays and qPCR. We found both IGHV mutated and unmutated CLL cells to respond with increased expression of MYC and other genes associated with BCR activation, and a phenotype of cell cycle progression. Genome-wide expression studies showed hsa-miR-132-3p/hsa-miR-212 miRNA cluster induction associated with a set of downregulated genes, enriched for genes modulated by BCR activation and amplified by Myc. We conclude that BCR triggering of CLL cells induces a transcriptional response of genes associated with BCR activation, enhanced cell cycle entry and progression and suggest that part of the transcriptional profiles linked to IGHV mutation status observed in isolated peripheral blood are not cell intrinsic but rather secondary to in vivo BCR stimulation. PMID:23560086

Changes in Polysome Association of mRNA Throughout Growth and Development in Arabidopsis thaliana.

PubMed

Yamasaki, Shotaro; Matsuura, Hideyuki; Demura, Taku; Kato, Ko

2015-11-01

Translational control is a key regulatory step in the expression of genes as proteins. In plant cells, the translational efficiency of mRNAs differs for different mRNA species, and the efficiency dynamically changes in various conditions. To gain a global view of translational control throughout growth and development, we performed genome-wide analysis of polysome association of mRNA during growth and leaf development in Arabidopsis thaliana by subjecting the mRNAs in polysomes to DNA microarray. This analysis revealed that the degree of polysome association of mRNA was different depending on the mRNA species, and the polysome association changed greatly throughout growth and development for each. In the growth stage, transcripts showed varying changes in polysome association from strongly depressed to unchanged, with the majority of transcripts showing dissociation from ribosomes. On the other hand, during leaf development, the polysome association of transcripts showed a normal distribution from repressed to activated mRNAs when comparing expanding and expanded leaves. In addition, functional category analysis of the microarray data suggested that translational control has a physiological significance in the plant growth and development process, especially in the categories of signaling and protein synthesis. In addition to this, we compared changes in polysome association of mRNAs between various conditions and characterized translational controls in each. This result suggested that mRNA translation might be controlled by complicated mechanisms for response to each condition. Our results highlight the importance of dynamic changes in mRNA translation in plant development and growth. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

The structural changes of T7 RNA polymerase from transcription initiation to elongation

PubMed Central

Steitz, Thomas A

2010-01-01

Summary The structures of T7 RNA polymerase (T7 RNAP) captured in the initiation and elongation phases of transcription, as well as an intermediate stage provide insights into how this RNA polymerase protein can initiate RNA synthesis and synthesize 7 to 10 nucleotides of RNA while remaining bound to the DNA promoter site. Recently, the structures of T7 RNAP bound to it promoter DNA along with either a 7 nucleotide or 8 nucleotide transcript show an elongated product site resulting from a 40° or 45° rotation of the promoter and domain that binds it. The different functional properties of the initiation and elongation phases of transcription are illuminated from structures of the initiation and elongation complexes. Structural insights into the translocation of the product transcript of RNAP, its separation of the downstream duplex DNA and its removal of the transcript from the heteroduplex are provided by the structures of several states of nucleotide incorporation. A conformational change in the “fingers” domain that results from the binding or dissociation of incoming NTP or PPi appears to be associated with the state of translocation of T7 RNAP. PMID:19811903

Detection of prostate cancer-specific transcripts in extracellular vesicles isolated from post-DRE urine

PubMed Central

Pellegrini, Kathryn L.; Patil, Dattatraya; Douglas, Kristen J.S.; Lee, Grace; Wehrmeyer, Kathryn; Torlak, Mersiha; Clark, Jeremy; Cooper, Colin S.; Moreno, Carlos S.; Sanda, Martin G.

2018-01-01

Background The measurement of gene expression in post-digital rectal examination (DRE) urine specimens provides a non-invasive method to determine a patient’s risk of prostate cancer. Many currently available assays use whole urine or cell pellets for the analysis of prostate cancer-associated genes, although the use of extracellular vesicles (EVs) has also recently been of interest. We investigated the expression of prostate-, kidney-, and bladder-specific transcripts and known prostate cancer biomarkers in urine EVs. Methods Cell pellets and EVs were recovered from post-DRE urine specimens, with the total RNA yield and quality determined by Bioanalyzer. The levels of prostate, kidney, and bladder-associated transcripts in EVs were assessed by TaqMan qPCR and targeted sequencing. Results RNA was more consistently recovered from the urine EV specimens, with over 80% of the patients demonstrating higher RNA yields in the EV fraction as compared to urine cell pellets. The median EV RNA yield of 36.4 ng was significantly higher than the median urine cell pellet RNA yield of 4.8 ng. Analysis of the post-DRE urine EVs indicated that prostate-specific transcripts were more abundant than kidney- or bladder-specific transcripts. Additionally, patients with prostate cancer had significantly higher levels of the prostate cancer-associated genes PCA3 and ERG. Conclusions Post-DRE urine EVs are a viable source of prostate-derived RNAs for biomarker discovery and prostate cancer status can be distinguished from analysis of these specimens. Continued analysis of urine EVs offers the potential discovery of novel biomarkers for pre-biopsy prostate cancer detection. PMID:28419548

Detection of prostate cancer-specific transcripts in extracellular vesicles isolated from post-DRE urine.

PubMed

Pellegrini, Kathryn L; Patil, Dattatraya; Douglas, Kristen J S; Lee, Grace; Wehrmeyer, Kathryn; Torlak, Mersiha; Clark, Jeremy; Cooper, Colin S; Moreno, Carlos S; Sanda, Martin G

2017-06-01

The measurement of gene expression in post-digital rectal examination (DRE) urine specimens provides a non-invasive method to determine a patient's risk of prostate cancer. Many currently available assays use whole urine or cell pellets for the analysis of prostate cancer-associated genes, although the use of extracellular vesicles (EVs) has also recently been of interest. We investigated the expression of prostate-, kidney-, and bladder-specific transcripts and known prostate cancer biomarkers in urine EVs. Cell pellets and EVs were recovered from post-DRE urine specimens, with the total RNA yield and quality determined by Bioanalyzer. The levels of prostate, kidney, and bladder-associated transcripts in EVs were assessed by TaqMan qPCR and targeted sequencing. RNA was more consistently recovered from the urine EV specimens, with over 80% of the patients demonstrating higher RNA yields in the EV fraction as compared to urine cell pellets. The median EV RNA yield of 36.4 ng was significantly higher than the median urine cell pellet RNA yield of 4.8 ng. Analysis of the post-DRE urine EVs indicated that prostate-specific transcripts were more abundant than kidney- or bladder-specific transcripts. Additionally, patients with prostate cancer had significantly higher levels of the prostate cancer-associated genes PCA3 and ERG. Post-DRE urine EVs are a viable source of prostate-derived RNAs for biomarker discovery and prostate cancer status can be distinguished from analysis of these specimens. Continued analysis of urine EVs offers the potential discovery of novel biomarkers for pre-biopsy prostate cancer detection. © 2017 Wiley Periodicals, Inc.

Splicing-independent loading of TREX on nascent RNA is required for efficient expression of dual-strand piRNA clusters in Drosophila

PubMed Central

Hur, Junho K.; Luo, Yicheng; Moon, Sungjin; Ninova, Maria; Marinov, Georgi K.; Chung, Yun D.; Aravin, Alexei A.

2016-01-01

The conserved THO/TREX (transcription/export) complex is critical for pre-mRNA processing and mRNA nuclear export. In metazoa, TREX is loaded on nascent RNA transcribed by RNA polymerase II in a splicing-dependent fashion; however, how TREX functions is poorly understood. Here we show that Thoc5 and other TREX components are essential for the biogenesis of piRNA, a distinct class of small noncoding RNAs that control expression of transposable elements (TEs) in the Drosophila germline. Mutations in TREX lead to defects in piRNA biogenesis, resulting in derepression of multiple TE families, gametogenesis defects, and sterility. TREX components are enriched on piRNA precursors transcribed from dual-strand piRNA clusters and colocalize in distinct nuclear foci that overlap with sites of piRNA transcription. The localization of TREX in nuclear foci and its loading on piRNA precursor transcripts depend on Cutoff, a protein associated with chromatin of piRNA clusters. Finally, we show that TREX is required for accumulation of nascent piRNA precursors. Our study reveals a novel splicing-independent mechanism for TREX loading on nascent RNA and its importance in piRNA biogenesis. PMID:27036967

Global transcriptional start site mapping using differential RNA sequencing reveals novel antisense RNAs in Escherichia coli.

PubMed

Thomason, Maureen K; Bischler, Thorsten; Eisenbart, Sara K; Förstner, Konrad U; Zhang, Aixia; Herbig, Alexander; Nieselt, Kay; Sharma, Cynthia M; Storz, Gisela

2015-01-01

While the model organism Escherichia coli has been the subject of intense study for decades, the full complement of its RNAs is only now being examined. Here we describe a survey of the E. coli transcriptome carried out using a differential RNA sequencing (dRNA-seq) approach, which can distinguish between primary and processed transcripts, and an automated prediction algorithm for transcriptional start sites (TSS). With the criterion of expression under at least one of three growth conditions examined, we predicted 14,868 TSS candidates, including 5,574 internal to annotated genes (iTSS) and 5,495 TSS corresponding to potential antisense RNAs (asRNAs). We examined expression of 14 candidate asRNAs by Northern analysis using RNA from wild-type E. coli and from strains defective for RNases III and E, two RNases reported to be involved in asRNA processing. Interestingly, nine asRNAs detected as distinct bands by Northern analysis were differentially affected by the rnc and rne mutations. We also compared our asRNA candidates with previously published asRNA annotations from RNA-seq data and discuss the challenges associated with these cross-comparisons. Our global transcriptional start site map represents a valuable resource for identification of transcription start sites, promoters, and novel transcripts in E. coli and is easily accessible, together with the cDNA coverage plots, in an online genome browser. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Computational assessment of the cooperativity between RNA binding proteins and MicroRNAs in Transcript Decay.

PubMed

Jiang, Peng; Singh, Mona; Coller, Hilary A

2013-01-01

Transcript degradation is a widespread and important mechanism for regulating protein abundance. Two major regulators of transcript degradation are RNA Binding Proteins (RBPs) and microRNAs (miRNAs). We computationally explored whether RBPs and miRNAs cooperate to promote transcript decay. We defined five RBP motifs based on the evolutionary conservation of their recognition sites in 3'UTRs as the binding motifs for Pumilio (PUM), U1A, Fox-1, Nova, and UAUUUAU. Recognition sites for some of these RBPs tended to localize at the end of long 3'UTRs. A specific group of miRNA recognition sites were enriched within 50 nts from the RBP recognition sites for PUM and UAUUUAU. The presence of both a PUM recognition site and a recognition site for preferentially co-occurring miRNAs was associated with faster decay of the associated transcripts. For PUM and its co-occurring miRNAs, binding of the RBP to its recognition sites was predicted to release nearby miRNA recognition sites from RNA secondary structures. The mammalian miRNAs that preferentially co-occur with PUM binding sites have recognition seeds that are reverse complements to the PUM recognition motif. Their binding sites have the potential to form hairpin secondary structures with proximal PUM binding sites that would normally limit RISC accessibility, but would be more accessible to miRNAs in response to the binding of PUM. In sum, our computational analyses suggest that a specific set of RBPs and miRNAs work together to affect transcript decay, with the rescue of miRNA recognition sites via RBP binding as one possible mechanism of cooperativity.

Mediator and RNA polymerase II clusters associate in transcription-dependent condensates.

PubMed

Cho, Won-Ki; Spille, Jan-Hendrik; Hecht, Micca; Lee, Choongman; Li, Charles; Grube, Valentin; Cisse, Ibrahim I

2018-06-21

Models of gene control have emerged from genetic and biochemical studies, with limited consideration of the spatial organization and dynamics of key components in living cells. Here we used live cell super-resolution and light sheet imaging to study the organization and dynamics of the Mediator coactivator and RNA polymerase II (Pol II) directly. Mediator and Pol II each form small transient and large stable clusters in living embryonic stem cells. Mediator and Pol II are colocalized in the stable clusters, which associate with chromatin, have properties of phase-separated condensates, and are sensitive to transcriptional inhibitors. We suggest that large clusters of Mediator, recruited by transcription factors at large or clustered enhancer elements, interact with large Pol II clusters in transcriptional condensates in vivo. Copyright © 2018, American Association for the Advancement of Science.

Genomic binding profiles of functionally distinct RNA polymerase III transcription complexes in human cells.

PubMed

Moqtaderi, Zarmik; Wang, Jie; Raha, Debasish; White, Robert J; Snyder, Michael; Weng, Zhiping; Struhl, Kevin

2010-05-01

Genome-wide occupancy profiles of five components of the RNA polymerase III (Pol III) machinery in human cells identified the expected tRNA and noncoding RNA targets and revealed many additional Pol III-associated loci, mostly near short interspersed elements (SINEs). Several genes are targets of an alternative transcription factor IIIB (TFIIIB) containing Brf2 instead of Brf1 and have extremely low levels of TFIIIC. Strikingly, expressed Pol III genes, unlike nonexpressed Pol III genes, are situated in regions with a pattern of histone modifications associated with functional Pol II promoters. TFIIIC alone associates with numerous ETC loci, via the B box or a novel motif. ETCs are often near CTCF binding sites, suggesting a potential role in chromosome organization. Our results suggest that human Pol III complexes associate preferentially with regions near functional Pol II promoters and that TFIIIC-mediated recruitment of TFIIIB is regulated in a locus-specific manner.

A new role of GCN2 in the nucleolus.

PubMed

Nakamura, Akito; Kimura, Hiromichi

2017-04-01

General control nonderepressible 2 (GCN2) is activated by the accumulation of uncharged tRNA in response to amino acid shortage and regulates amino acid starvation response in the cytosol. Here we report the nucleolar localization of GCN2 and the association between GCN2 and small RNA transcripts. Immunofluorescence analysis revealed that GCN2 was constitutively localized to the nucleolus or recruited to the nucleolus by amino acid starvation stress. The nucleolus is the largest structure in the nucleus, where it primarily serves as the site of ribosome and RNA synthesis in addition to acting as a stress sensor through the regulation of p53 function. We found that siRNA-mediated depletion of GCN2 increases small RNA transcripts such as tRNA and 5S rRNA, and induces the p53 pathway activation. Derepression of these transcripts and p53 pathway activation by GCN2 depletion was restored by depletion of B-related factor 1 (BRF1), a primary subunit of RNA polymerase III (pol III) components. These data suggest that the excess amount of small RNA transcripts following GCN2 depletion was responsible for the p53 activation. Our findings reveal a role of GCN2 in the nucleolus that is involved in the expression of small RNA transcripts and serves as alternative stress-sensing machinery for nutrient deficiency. Thus, GCN2 may play pivotal roles in multiple protein translation checkpoints in both the nucleolus and cytosol. Copyright © 2017 Elsevier Inc. All rights reserved.

The long non-coding RNA PARTICLE is associated with WWOX and the absence of FRA16D breakage in osteosarcoma patients.

PubMed

O'Leary, Valerie Bríd; Maugg, Doris; Smida, Jan; Baumhoer, Daniel; Nathrath, Michaela; Ovsepian, Saak Victor; Atkinson, Michael John

2017-10-20

Breakage of the fragile site FRA16D disrupts the WWOX (WW Domain Containing Oxidoreductase) tumor suppressor gene in osteosarcoma. However, the frequency of breakage is not sufficient to explain the rate of WWOX loss in pathogenesis. The involvement of non-coding RNA transcripts is proposed due to their accumulation at fragile sites, where they are advocated to influence specific chromosomal regions associated with malignancy. The long ncRNA PARTICLE (promoter of MAT2A antisense radiation-induced circulating long non-coding RNA) is transiently elevated in response to irradiation and influences epigenetic silencing modification within WWOX . It now emerges that elevated PARTICLE levels are significantly associated with FRA16D non-breakage in OS patients. Although not associated with overall survival, high PARTICLE levels were found to be significantly linked to metastasis free outcome. The transcription of both PARTICLE and WWOX are transiently responsive to exposure to low doses of radiation in osteosarcoma cell lines. Herein, a relationship between WWOX and PARTICLE transcription is suggested in human osteosarcoma cell lines representing alternative genetic backgrounds. PARTICLE over-expression ameliorated WWOX promoter activity in U2OS harboring FRA16D non-breakage. It can be concluded that the lncRNA PARTICLE influences the WWOX tumor suppressor and in the absence of WWOX FRA16D breakage, it is associated with OS metastasis-free survival.

CDK9-Dependent Transcriptional Elongation in the Innate Interferon-Stimulated Gene Response to Respiratory Syncytial Virus Infection in Airway Epithelial Cells

PubMed Central

Tian, Bing; Zhao, Yingxin; Kalita, Mridul; Edeh, Chukwudi B.; Paessler, Slobodan; Casola, Antonella; Teng, Michael N.; Garofalo, Roberto P.

2013-01-01

Respiratory syncytial virus (RSV) is a negative-sense single-stranded RNA virus responsible for lower respiratory tract infections. During infection, the presence of double-stranded RNA (dsRNA) activates the interferon (IFN) regulatory factor 3 (IRF3) transcription factor, an event triggering expression of immediate early, IFN-stimulated genes (ISGs). We examine the role of transcriptional elongation in control of IRF3-dependent ISG expression. RSV infection induces ISG54, ISG56, and CIG5 gene expression in an IRF3-dependent manner demonstrated by IRF3 small interfering RNA (siRNA) silencing in both A549 epithelial cells and IRF3−/− MEFs. ISG expression was mediated by the recruitment of IRF3, CDK9, polymerase II (Pol II), and phospho-Ser2 carboxy-terminal domain (CTD) Pol II to the IFN-stimulated response element (ISRE) binding sites of the IRF3-dependent ISG promoters in native chromatin. We find that RSV infection enhances the activated fraction of cyclin-dependent kinase 9 (CDK9) by promoting its association with bromodomain 4 (BRD4) and disrupting its association with the inhibitory 7SK small nuclear RNA. The requirement of CDK9 activity for ISG expression was shown by siRNA-mediated silencing of CDK9 and by a selective CDK9 inhibitor in A549 cells. In contrast, RSV-induced beta interferon (IFN-β) expression is not influenced by CDK9 inhibition. Using transcript-selective quantitative real-time reverse transcription-PCR (Q-RT-PCR) assays for the ISG54 gene, we observed that RSV induces transition from short to fully spliced mRNA transcripts and that this transition is blocked by CDK9 inhibition in both A549 and primary human small airway epithelial cells. These data indicate that transcription elongation plays a major role in RSV-induced ISG expression and is mediated by IRF3-dependent recruitment of activated CDK9. CDK9 activity may be a target for immunomodulation in RSV-induced lung disease. PMID:23596302

Promoter architecture dictates cell-to-cell variability in gene expression.

PubMed

Jones, Daniel L; Brewster, Robert C; Phillips, Rob

2014-12-19

Variability in gene expression among genetically identical cells has emerged as a central preoccupation in the study of gene regulation; however, a divide exists between the predictions of molecular models of prokaryotic transcriptional regulation and genome-wide experimental studies suggesting that this variability is indifferent to the underlying regulatory architecture. We constructed a set of promoters in Escherichia coli in which promoter strength, transcription factor binding strength, and transcription factor copy numbers are systematically varied, and used messenger RNA (mRNA) fluorescence in situ hybridization to observe how these changes affected variability in gene expression. Our parameter-free models predicted the observed variability; hence, the molecular details of transcription dictate variability in mRNA expression, and transcriptional noise is specifically tunable and thus represents an evolutionarily accessible phenotypic parameter. Copyright © 2014, American Association for the Advancement of Science.

A Herpesviral Immediate Early Protein Promotes Transcription Elongation of Viral Transcripts.

PubMed

Fox, Hannah L; Dembowski, Jill A; DeLuca, Neal A

2017-06-13

Herpes simplex virus 1 (HSV-1) genes are transcribed by cellular RNA polymerase II (RNA Pol II). While four viral immediate early proteins (ICP4, ICP0, ICP27, and ICP22) function in some capacity in viral transcription, the mechanism by which ICP22 functions remains unclear. We observed that the FACT complex (comprised of SSRP1 and Spt16) was relocalized in infected cells as a function of ICP22. ICP22 was also required for the association of FACT and the transcription elongation factors SPT5 and SPT6 with viral genomes. We further demonstrated that the FACT complex interacts with ICP22 throughout infection. We therefore hypothesized that ICP22 recruits cellular transcription elongation factors to viral genomes for efficient transcription elongation of viral genes. We reevaluated the phenotype of an ICP22 mutant virus by determining the abundance of all viral mRNAs throughout infection by transcriptome sequencing (RNA-seq). The accumulation of almost all viral mRNAs late in infection was reduced compared to the wild type, regardless of kinetic class. Using chromatin immunoprecipitation sequencing (ChIP-seq), we mapped the location of RNA Pol II on viral genes and found that RNA Pol II levels on the bodies of viral genes were reduced in the ICP22 mutant compared to wild-type virus. In contrast, the association of RNA Pol II with transcription start sites in the mutant was not reduced. Taken together, our results indicate that ICP22 plays a role in recruiting elongation factors like the FACT complex to the HSV-1 genome to allow for efficient viral transcription elongation late in viral infection and ultimately infectious virion production. IMPORTANCE HSV-1 interacts with many cellular proteins throughout productive infection. Here, we demonstrate the interaction of a viral protein, ICP22, with a subset of cellular proteins known to be involved in transcription elongation. We determined that ICP22 is required to recruit the FACT complex and other transcription elongation factors to viral genomes and that in the absence of ICP22 viral transcription is globally reduced late in productive infection, due to an elongation defect. This insight defines a fundamental role of ICP22 in HSV-1 infection and elucidates the involvement of cellular factors in HSV-1 transcription. Copyright © 2017 Fox et al.

Sperm RNA elements as markers of health.

PubMed

Burl, Rayanne B; Clough, Stephanie; Sendler, Edward; Estill, Molly; Krawetz, Stephen A

2018-02-01

Idiopathic infertility, an etiology not identified as part of standard clinical assessment, represents approximately 20% of all infertility cases. Current male infertility diagnosis focuses on the concentration, motility, and morphology of spermatozoa. This is of limited value when predicting birth success and of limited utility when selecting the optimum treatment. At fertilization, spermatozoa provide their genomic contribution, as well as a set of RNAs and proteins that have distinct roles in development. The potential of spermatozoal RNAs to be used as a prognostic of live birth has been shown [Jodar et al. (2015) Science Translational Medicine 7(295):295re6]. This relied on a set of 648 sperm RNA elements derived from 285 genes that are perhaps indicative of future health status. To address this tenet, the present study correlated the levels of each transcript among all samples to assess linkage between transcript absence, birth success, and possible disease association. Correlations between transcript levels of the 285 genes were analyzed amongst themselves, and within the context of the entire transcript population for these samples. The transcripts ACE, GIGYF2, and ODF2 had many negative correlations and form the majority of correlations, suggesting an important function for these transcripts. Eleven of the 285 queried genes had disease-associated variants within a sperm RNA element. Three genes, GPX4, NDRG1, and RPS24 had SREs were absent in at least one individual from the test cohort. GPX4 and RPS24 are associated with developmental defects and/or neonatal lethality. This leaves the intriguing possibility that, while sperm RNAs delivered to the oocyte inform the success of live birth, they may also be predictors of human health. GO: Gene Ontology; ART: assisted reproductive technology; IVF: in vitro fertilization; ICSI: intra-cytoplasmic sperm injection; RNA-seq: RNA-sequencing; TIC: timed intercourse; IUI: intrauterine insemination; SRE: sperm RNA elements; HPA: Human Protein Atlas; SMDS: sedaghatian-type spondylometaphyseal dysplasia; DBA: Diamond-Blackfan anemia; RPKM: reads per kilobase per million; TPM: transcripts per million; IPA: Ingenuity Pathway Analysis; OMIM: Online Mendelian Inheritance in Man.

Long non-coding RNA produced by RNA polymerase V determines boundaries of heterochromatin

PubMed Central

Böhmdorfer, Gudrun; Sethuraman, Shriya; Rowley, M Jordan; Krzyszton, Michal; Rothi, M Hafiz; Bouzit, Lilia; Wierzbicki, Andrzej T

2016-01-01

RNA-mediated transcriptional gene silencing is a conserved process where small RNAs target transposons and other sequences for repression by establishing chromatin modifications. A central element of this process are long non-coding RNAs (lncRNA), which in Arabidopsis thaliana are produced by a specialized RNA polymerase known as Pol V. Here we show that non-coding transcription by Pol V is controlled by preexisting chromatin modifications located within the transcribed regions. Most Pol V transcripts are associated with AGO4 but are not sliced by AGO4. Pol V-dependent DNA methylation is established on both strands of DNA and is tightly restricted to Pol V-transcribed regions. This indicates that chromatin modifications are established in close proximity to Pol V. Finally, Pol V transcription is preferentially enriched on edges of silenced transposable elements, where Pol V transcribes into TEs. We propose that Pol V may play an important role in the determination of heterochromatin boundaries. DOI: http://dx.doi.org/10.7554/eLife.19092.001 PMID:27779094

Transcriptome analysis using next generation sequencing reveals molecular signatures of diabetic retinopathy and efficacy of candidate drugs.

PubMed

Kandpal, Raj P; Rajasimha, Harsha K; Brooks, Matthew J; Nellissery, Jacob; Wan, Jun; Qian, Jiang; Kern, Timothy S; Swaroop, Anand

2012-01-01

To define gene expression changes associated with diabetic retinopathy in a mouse model using next generation sequencing, and to utilize transcriptome signatures to assess molecular pathways by which pharmacological agents inhibit diabetic retinopathy. We applied a high throughput RNA sequencing (RNA-seq) strategy using Illumina GAIIx to characterize the entire retinal transcriptome from nondiabetic and from streptozotocin-treated mice 32 weeks after induction of diabetes. Some of the diabetic mice were treated with inhibitors of receptor for advanced glycation endproducts (RAGE) and p38 mitogen activated protein (MAP) kinase, which have previously been shown to inhibit diabetic retinopathy in rodent models. The transcripts and alternatively spliced variants were determined in all experimental groups. Next generation sequencing-based RNA-seq profiles provided comprehensive signatures of transcripts that are altered in early stages of diabetic retinopathy. These transcripts encoded proteins involved in distinct yet physiologically relevant disease-associated pathways such as inflammation, microvasculature formation, apoptosis, glucose metabolism, Wnt signaling, xenobiotic metabolism, and photoreceptor biology. Significant upregulation of crystallin transcripts was observed in diabetic animals, and the diabetes-induced upregulation of these transcripts was inhibited in diabetic animals treated with inhibitors of either RAGE or p38 MAP kinase. These two therapies also showed dissimilar regulation of some subsets of transcripts that included alternatively spliced versions of arrestin, neutral sphingomyelinase activation associated factor (Nsmaf), SH3-domain GRB2-like interacting protein 1 (Sgip1), and axin. Diabetes alters many transcripts in the retina, and two therapies that inhibit the vascular pathology similarly inhibit a portion of these changes, pointing to possible molecular mechanisms for their beneficial effects. These therapies also changed the abundance of various alternatively spliced versions of signaling transcripts, suggesting a possible role of alternative splicing in disease etiology. Our studies clearly demonstrate RNA-seq as a comprehensive strategy for identifying disease-specific transcripts, and for determining comparative profiles of molecular changes mediated by candidate drugs.

Circular RNAs (circRNAs) in Health and Disease

PubMed Central

Haque, Shahnaz; Harries, Lorna W.

2017-01-01

Splicing events do not always produce a linear transcript. Circular RNAs (circRNAs) are a class of RNA that are emerging as key new members of the gene regulatory milieu, which are produced by back-splicing events within genes. In circRNA formation, rather than being spliced in a linear fashion, exons can be circularised by use of the 3′ acceptor splice site of an upstream exon, leading to the formation of a circular RNA species. circRNAs have been demonstrated across species and have the potential to present genetic information in new orientations distinct from their parent transcript. The importance of these RNA players in gene regulation and normal cellular homeostasis is now beginning to be recognised. They have several potential modes of action, from serving as sponges for micro RNAs and RNA binding proteins, to acting as transcriptional regulators. In accordance with an important role in the normal biology of the cell, perturbations of circRNA expression are now being reported in association with disease. Furthermore, the inherent stability of circRNAs conferred by their circular structure and exonuclease resistance, and their expression in blood and other peripheral tissues in association with endosomes and microvesicles, renders them excellent candidates as disease biomarkers. In this review, we explore the state of knowledge on this exciting class of transcripts in regulating gene expression and discuss their emerging role in health and disease. PMID:29182528

Analysis of the siRNA-Mediated Gene Silencing Process Targeting Three Homologous Genes Controlling Soybean Seed Oil Quality.

PubMed

Lu, Sha; Yin, Xiaoyan; Spollen, William; Zhang, Ning; Xu, Dong; Schoelz, James; Bilyeu, Kristin; Zhang, Zhanyuan J

2015-01-01

In the past decade, RNA silencing has gained significant attention because of its success in genomic scale research and also in the genetic improvement of crop plants. However, little is known about the molecular basis of siRNA processing in association with its target transcript. To reveal this process for improving hpRNA-mediated gene silencing in crop plants, the soybean GmFAD3 gene family was chosen as a test model. We analyzed RNAi mutant soybean lines in which three members of the GmFAD3 gene family were silenced. The silencing levels of FAD3A, FAD3B and FAD3C were correlated with the degrees of sequence homology between the inverted repeat of hpRNA and the GmFAD3 transcripts in the RNAi lines. Strikingly, transgenes in two of the three RNAi lines were heavily methylated, leading to a dramatic reduction of hpRNA-derived siRNAs. Small RNAs corresponding to the loop portion of the hairpin transcript were detected while much lower levels of siRNAs were found outside of the target region. siRNAs generated from the 318-bp inverted repeat were found to be diced much more frequently at stem sequences close to the loop and associated with the inferred cleavage sites on the target transcripts, manifesting "hot spots". The top candidate hpRNA-derived siRNA share certain sequence features with mature miRNA. This is the first comprehensive and detailed study revealing the siRNA-mediated gene silencing mechanism in crop plants using gene family GmFAD3 as a test model.

Inference of alternative splicing from RNA-Seq data with probabilistic splice graphs

PubMed Central

LeGault, Laura H.; Dewey, Colin N.

2013-01-01

Motivation: Alternative splicing and other processes that allow for different transcripts to be derived from the same gene are significant forces in the eukaryotic cell. RNA-Seq is a promising technology for analyzing alternative transcripts, as it does not require prior knowledge of transcript structures or genome sequences. However, analysis of RNA-Seq data in the presence of genes with large numbers of alternative transcripts is currently challenging due to efficiency, identifiability and representation issues. Results: We present RNA-Seq models and associated inference algorithms based on the concept of probabilistic splice graphs, which alleviate these issues. We prove that our models are often identifiable and demonstrate that our inference methods for quantification and differential processing detection are efficient and accurate. Availability: Software implementing our methods is available at http://deweylab.biostat.wisc.edu/psginfer. Contact: cdewey@biostat.wisc.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:23846746

Association between long non-coding RNA polymorphisms and cancer risk: a meta-analysis.

PubMed

Huang, Xin; Zhang, Weiyue; Shao, Zengwu

2018-05-25

Several studies have suggested that long non-coding RNA (lncRNA) gene polymorphisms are associated with cancer risk. In the present study, we conducted a meta-analysis related to studies on the association between lncRNA single-nucleotide polymorphisms (SNPs) and the overall risk of cancer. A total 12 SNPs in five common lncRNA genes were finally included in the meta-analysis. In the lncRNA antisense noncoding RNA in the INK4 locus (ANRIL), the rs1333048 A/C, rs4977574 A/G, and rs10757278 A/G polymorphisms, but not rs1333045 C/T, were correlated with overall cancer risk. Our study also demonstrated that other SNPs were correlated with overall cancer risk, namely, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1, rs619586 A/G), HOXA distal transcript antisense RNA (HOTTIP, rs1859168 A/C) and highly up-regulated in liver cancer (HULC, rs7763881 A/C). Moreover, four prostate cancer‑associated non‑coding RNA 1 (PRNCR1, rs16901946 G/A, rs13252298 G/A, rs1016343 T/C, and rs1456315 G/A) SNPs were in association with cancer risk. No association was found between the PRNCR1 (rs7007694 C/T) SNP and the risk of cancer. In conclusion, our results suggest that several studied lncRNA SNPs are associated with overall cancer risk. Therefore, they might be potential predictive biomarkers for the risk of cancer. More studies based on larger sample sizes and more lncRNA SNPs are warranted to confirm these findings. ©2018 The Author(s).

Evaluation of the effectiveness of semen storage and sperm purification methods for spermatozoa transcript profiling.

PubMed

Mao, Shihong; Goodrich, Robert J; Hauser, Russ; Schrader, Steven M; Chen, Zhen; Krawetz, Stephen A

2013-10-01

Different semen storage and sperm purification methods may affect the integrity of isolated spermatozoal RNA. RNA-Seq was applied to determine whether semen storage methods (pelleted vs. liquefied) and somatic cell lysis buffer (SCLB) vs. PureSperm (PS) purification methods affect the quantity and quality of sperm RNA. The results indicate that the method of semen storage does not markedly impact RNA profiling whereas the choice of purification can yield significant differences. RNA-Seq showed that the majority of mitochondrial and mid-piece associated transcripts were lost after SCLB purification, which indicated that the mid-piece of spermatozoa may have been compromised. In addition, the number of stable transcript pairs from SCLB-samples was less than that from the PS samples. This study supports the view that PS purification better maintains the integrity of spermatozoal RNAs.

Pnrc2 regulates 3'UTR-mediated decay of segmentation clock-associated transcripts during zebrafish segmentation.

PubMed

Gallagher, Thomas L; Tietz, Kiel T; Morrow, Zachary T; McCammon, Jasmine M; Goldrich, Michael L; Derr, Nicolas L; Amacher, Sharon L

2017-09-01

Vertebrate segmentation is controlled by the segmentation clock, a molecular oscillator that regulates gene expression and cycles rapidly. The expression of many genes oscillates during segmentation, including hairy/Enhancer of split-related (her or Hes) genes, which encode transcriptional repressors that auto-inhibit their own expression, and deltaC (dlc), which encodes a Notch ligand. We previously identified the tortuga (tor) locus in a zebrafish forward genetic screen for genes involved in cyclic transcript regulation and showed that cyclic transcripts accumulate post-splicing in tor mutants. Here we show that cyclic mRNA accumulation in tor mutants is due to loss of pnrc2, which encodes a proline-rich nuclear receptor co-activator implicated in mRNA decay. Using an inducible in vivo reporter system to analyze transcript stability, we find that the her1 3'UTR confers Pnrc2-dependent instability to a heterologous transcript. her1 mRNA decay is Dicer-independent and likely employs a Pnrc2-Upf1-containing mRNA decay complex. Surprisingly, despite accumulation of cyclic transcripts in pnrc2-deficient embryos, we find that cyclic protein is expressed normally. Overall, we show that Pnrc2 promotes 3'UTR-mediated decay of developmentally-regulated segmentation clock transcripts and we uncover an additional post-transcriptional regulatory layer that ensures oscillatory protein expression in the absence of cyclic mRNA decay. Copyright © 2017 Elsevier Inc. All rights reserved.

Introns Protect Eukaryotic Genomes from Transcription-Associated Genetic Instability.

PubMed

Bonnet, Amandine; Grosso, Ana R; Elkaoutari, Abdessamad; Coleno, Emeline; Presle, Adrien; Sridhara, Sreerama C; Janbon, Guilhem; Géli, Vincent; de Almeida, Sérgio F; Palancade, Benoit

2017-08-17

Transcription is a source of genetic instability that can notably result from the formation of genotoxic DNA:RNA hybrids, or R-loops, between the nascent mRNA and its template. Here we report an unexpected function for introns in counteracting R-loop accumulation in eukaryotic genomes. Deletion of endogenous introns increases R-loop formation, while insertion of an intron into an intronless gene suppresses R-loop accumulation and its deleterious impact on transcription and recombination in yeast. Recruitment of the spliceosome onto the mRNA, but not splicing per se, is shown to be critical to attenuate R-loop formation and transcription-associated genetic instability. Genome-wide analyses in a number of distant species differing in their intron content, including human, further revealed that intron-containing genes and the intron-richest genomes are best protected against R-loop accumulation and subsequent genetic instability. Our results thereby provide a possible rationale for the conservation of introns throughout the eukaryotic lineage. Copyright © 2017 Elsevier Inc. All rights reserved.

Oncogenes and RNA splicing of human tumor viruses

PubMed Central

Ajiro, Masahiko; Zheng, Zhi-Ming

2014-01-01

Approximately 10.8% of human cancers are associated with infection by an oncogenic virus. These viruses include human papillomavirus (HPV), Epstein–Barr virus (EBV), Merkel cell polyomavirus (MCV), human T-cell leukemia virus 1 (HTLV-1), Kaposi's sarcoma-associated herpesvirus (KSHV), hepatitis C virus (HCV) and hepatitis B virus (HBV). These oncogenic viruses, with the exception of HCV, require the host RNA splicing machinery in order to exercise their oncogenic activities, a strategy that allows the viruses to efficiently export and stabilize viral RNA and to produce spliced RNA isoforms from a bicistronic or polycistronic RNA transcript for efficient protein translation. Infection with a tumor virus affects the expression of host genes, including host RNA splicing factors, which play a key role in regulating viral RNA splicing of oncogene transcripts. A current prospective focus is to explore how alternative RNA splicing and the expression of viral oncogenes take place in a cell- or tissue-specific manner in virus-induced human carcinogenesis. PMID:26038756

Coordination of tRNA transcription with export at nuclear pore complexes in budding yeast.

PubMed

Chen, Miao; Gartenberg, Marc R

2014-05-01

tRNAs are encoded by RNA polymerase III-transcribed genes that reside at seemingly random intervals along the chromosomes of budding yeast. Existing evidence suggests that the genes congregate together at the nucleolus and/or centromeres. In this study, we re-examined spatial and temporal aspects of tRNA gene (tDNA) expression. We show that tDNA transcription fluctuates during cell cycle progression. In M phase, when tRNA synthesis peaks, tDNAs localize at nuclear pore complexes (NPCs). Docking of a tDNA requires the DNA sequence of the contacted gene, nucleoporins Nup60 and Nup2, and cohesin. Characterization of mutants that block NPC localization revealed that docking is a consequence of elevated tDNA transcription. NPC-tDNA contact falters in the absence of the principal exportin of nascent tRNA, Los1, and genetic assays indicate that gating of tDNAs at NPCs favors cytoplasmic accumulation of functional tRNA. Collectively, the data suggest that tDNAs associate with NPCs to coordinate RNA polymerase III transcription with the nuclear export of pre-tRNA. The M-phase specificity of NPC contact reflects a regulatory mechanism that may have evolved, in part, to avoid collisions between DNA replication forks and transcribing RNA polymerase III machinery at NPCs.

Coordination of tRNA transcription with export at nuclear pore complexes in budding yeast

PubMed Central

Chen, Miao; Gartenberg, Marc R.

2014-01-01

tRNAs are encoded by RNA polymerase III-transcribed genes that reside at seemingly random intervals along the chromosomes of budding yeast. Existing evidence suggests that the genes congregate together at the nucleolus and/or centromeres. In this study, we re-examined spatial and temporal aspects of tRNA gene (tDNA) expression. We show that tDNA transcription fluctuates during cell cycle progression. In M phase, when tRNA synthesis peaks, tDNAs localize at nuclear pore complexes (NPCs). Docking of a tDNA requires the DNA sequence of the contacted gene, nucleoporins Nup60 and Nup2, and cohesin. Characterization of mutants that block NPC localization revealed that docking is a consequence of elevated tDNA transcription. NPC–tDNA contact falters in the absence of the principal exportin of nascent tRNA, Los1, and genetic assays indicate that gating of tDNAs at NPCs favors cytoplasmic accumulation of functional tRNA. Collectively, the data suggest that tDNAs associate with NPCs to coordinate RNA polymerase III transcription with the nuclear export of pre-tRNA. The M-phase specificity of NPC contact reflects a regulatory mechanism that may have evolved, in part, to avoid collisions between DNA replication forks and transcribing RNA polymerase III machinery at NPCs. PMID:24788517

Transcripts with in silico predicted RNA structure are enriched everywhere in the mouse brain

PubMed Central

2012-01-01

Background Post-transcriptional control of gene expression is mostly conducted by specific elements in untranslated regions (UTRs) of mRNAs, in collaboration with specific binding proteins and RNAs. In several well characterized cases, these RNA elements are known to form stable secondary structures. RNA secondary structures also may have major functional implications for long noncoding RNAs (lncRNAs). Recent transcriptional data has indicated the importance of lncRNAs in brain development and function. However, no methodical efforts to investigate this have been undertaken. Here, we aim to systematically analyze the potential for RNA structure in brain-expressed transcripts. Results By comprehensive spatial expression analysis of the adult mouse in situ hybridization data of the Allen Mouse Brain Atlas, we show that transcripts (coding as well as non-coding) associated with in silico predicted structured probes are highly and significantly enriched in almost all analyzed brain regions. Functional implications of these RNA structures and their role in the brain are discussed in detail along with specific examples. We observe that mRNAs with a structure prediction in their UTRs are enriched for binding, transport and localization gene ontology categories. In addition, after manual examination we observe agreement between RNA binding protein interaction sites near the 3’ UTR structures and correlated expression patterns. Conclusions Our results show a potential use for RNA structures in expressed coding as well as noncoding transcripts in the adult mouse brain, and describe the role of structured RNAs in the context of intracellular signaling pathways and regulatory networks. Based on this data we hypothesize that RNA structure is widely involved in transcriptional and translational regulatory mechanisms in the brain and ultimately plays a role in brain function. PMID:22651826

Unraveling the oral cancer lncRNAome: Identification of novel lncRNAs associated with malignant progression and HPV infection.

PubMed

Nohata, Nijiro; Abba, Martin C; Gutkind, J Silvio

2016-08-01

The role of long non-coding RNA (lncRNA) expression in human head and neck squamous cell carcinoma (HNSCC) is still poorly understood. In this study, we aimed at establishing the onco-lncRNAome profiling of HNSCC and to identify lncRNAs correlating with prognosis and patient survival. The Atlas of Noncoding RNAs in Cancer (TANRIC) database was employed to retrieve the lncRNA expression information generated from The Cancer Genome Atlas (TCGA) HNSCC RNA-sequencing data. RNA-sequencing data from HNSCC cell lines were also considered for this study. Bioinformatics approaches, such as differential gene expression analysis, survival analysis, principal component analysis, and Co-LncRNA enrichment analysis were performed. Using TCGA HNSCC RNA-sequencing data from 426 HNSCC and 42 adjacent normal tissues, we found 728 lncRNA transcripts significantly and differentially expressed in HNSCC. Among the 728 lncRNAs, 55 lncRNAs were significantly associated with poor prognosis, such as overall survival and/or disease-free survival. Next, we found 140 lncRNA transcripts significantly and differentially expressed between Human Papilloma Virus (HPV) positive tumors and HPV negative tumors. Thirty lncRNA transcripts were differentially expressed between TP53 mutated and TP53 wild type tumors. Co-LncRNA analysis suggested that protein-coding genes that are co-expressed with these deregulated lncRNAs might be involved in cancer associated molecular events. With consideration of differential expression of lncRNAs in a HNSCC cell lines panel (n=22), we found several lncRNAs that may represent potential targets for diagnosis, therapy and prevention of HNSCC. LncRNAs profiling could provide novel insights into the potential mechanisms of HNSCC oncogenesis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Unraveling the Oral Cancer lncRNAome: Identification of Novel lncRNAs Associated with Malignant Progression and HPV Infection

PubMed Central

Nohata, Nijiro; Abba, Martin C.; Gutkind, J. Silvio

2017-01-01

Objectives The role of long non-coding RNA (lncRNA) expression in human head and neck squamous cell carcinoma (HNSCC) is still poorly understood. In this study, we aimed at establishing the onco-lncRNAome profiling of HNSCC and to identify lncRNAs correlating with prognosis and patient survival. Materials and Methods The Atlas of Noncoding RNAs in Cancer (TANRIC) database was employed to retrieve the lncRNA expression information generated from The Cancer Genome Atlas (TCGA) HNSCC RNA-sequencing data. RNA-sequencing data from HNSCC cell lines were also considered for this study. Bioinformatics approaches, such as differential gene expression analysis, survival analysis, principal component analysis, and Co-LncRNA enrichment analysis were performed. Results Using TCGA HNSCC RNA-sequencing data from 426 HNSCC and 42 adjacent normal tissues, we found 728 lncRNA transcripts significantly and differentially expressed in HNSCC. Among the 728 lncRNAs, 55 lncRNAs were significantly associated with poor prognosis, such as overall survival and/or disease-free survival. Next, we found 140 lncRNA transcripts significantly and differentially expressed between Human Papilloma Virus (HPV) positive tumors and HPV negative tumors. Thirty lncRNA transcripts were differentially expressed between TP53 mutated and TP53 wild type tumors. Co-LncRNA analysis suggested that protein-coding genes that are co-expressed with these deregulated lncRNAs might be involved in cancer associated molecular events. With consideration of differential expression of lncRNAs in a HNSCC cell lines panel (n=22), we found several lncRNAs that may represent potential targets for diagnosis, therapy and prevention of HNSCC. Conclusion LncRNAs profiling could provide novel insights into the potential mechanisms of HNSCC oncogenesis. PMID:27424183

piRNA-associated proteins and retrotransposons are differentially expressed in murine testis and ovary of aryl hydrocarbon receptor deficient mice

PubMed Central

Rico-Leo, Eva M.; Moreno-Marín, Nuria; González-Rico, Francisco J.; Barrasa, Eva; Ortega-Ferrusola, Cristina; Martín-Muñoz, Patricia; Sánchez-Guardado, Luis O.; Llano, Elena; Alvarez-Barrientos, Alberto; Infante-Campos, Ascensión; Catalina-Fernández, Inmaculada; Hidalgo-Sánchez, Matías; de Rooij, Dirk G.; Pendás, Alberto M.; Peña, Fernando J.; Merino, Jaime M.

2016-01-01

Previous studies suggested that the aryl hydrocarbon receptor (AhR) contributes to mice reproduction and fertility. However, the mechanisms involved remain mostly unknown. Retrotransposon silencing by Piwi-interacting RNAs (piRNAs) is essential for germ cell maturation and, remarkably, AhR has been identified as a regulator of murine B1-SINE retrotransposons. Here, using littermate AhR+/+ and AhR−/− mice, we report that AhR regulates the general course of spermatogenesis and oogenesis by a mechanism likely to be associated with piRNA-associated proteins, piRNAs and retrotransposons. piRNA-associated proteins MVH and Miwi are upregulated in leptotene to pachytene spermatocytes with a more precocious timing in AhR−/− than in AhR+/+ testes. piRNAs and transcripts from B1-SINE, LINE-1 and IAP retrotransposons increased at these meiotic stages in AhR-null testes. Moreover, B1-SINE transcripts colocalize with MVH and Miwi in leptonema and pachynema spermatocytes. Unexpectedly, AhR−/− males have increased sperm counts, higher sperm functionality and enhanced fertility than AhR+/+ mice. In contrast, piRNA-associated proteins and B1-SINE and IAP-derived transcripts are reduced in adult AhR−/− ovaries. Accordingly, AhR-null female mice have lower numbers of follicles when compared with AhR+/+ mice. Thus, AhR deficiency differentially affects testis and ovary development possibly by a process involving piRNA-associated proteins, piRNAs and transposable elements. PMID:28003471

Circulating neutrophil transcriptome may reveal intracranial aneurysm signature

PubMed Central

Tutino, Vincent M.; Poppenberg, Kerry E.; Jiang, Kaiyu; Jarvis, James N.; Sun, Yijun; Sonig, Ashish; Siddiqui, Adnan H.; Snyder, Kenneth V.; Levy, Elad I.; Kolega, John

2018-01-01

Background Unruptured intracranial aneurysms (IAs) are typically asymptomatic and undetected except for incidental discovery on imaging. Blood-based diagnostic biomarkers could lead to improvements in IA management. This exploratory study examined circulating neutrophils to determine whether they carry RNA expression signatures of IAs. Methods Blood samples were collected from patients receiving cerebral angiography. Eleven samples were collected from patients with IAs and 11 from patients without IAs as controls. Samples from the two groups were paired based on demographics and comorbidities. RNA was extracted from isolated neutrophils and subjected to next-generation RNA sequencing to obtain differential expressions for identification of an IA-associated signature. Bioinformatics analyses, including gene set enrichment analysis and Ingenuity Pathway Analysis, were used to investigate the biological function of all differentially expressed transcripts. Results Transcriptome profiling identified 258 differentially expressed transcripts in patients with and without IAs. Expression differences were consistent with peripheral neutrophil activation. An IA-associated RNA expression signature was identified in 82 transcripts (p<0.05, fold-change ≥2). This signature was able to separate patients with and without IAs on hierarchical clustering. Furthermore, in an independent, unpaired, replication cohort of patients with IAs (n = 5) and controls (n = 5), the 82 transcripts separated 9 of 10 patients into their respective groups. Conclusion Preliminary findings show that RNA expression from circulating neutrophils carries an IA-associated signature. These findings highlight a potential to use predictive biomarkers from peripheral blood samples to identify patients with IAs. PMID:29342213

Analysis of Antisense Expression by Whole Genome Tiling Microarrays and siRNAs Suggests Mis-Annotation of Arabidopsis Orphan Protein-Coding Genes

PubMed Central

Richardson, Casey R.; Luo, Qing-Jun; Gontcharova, Viktoria; Jiang, Ying-Wen; Samanta, Manoj; Youn, Eunseog; Rock, Christopher D.

2010-01-01

Background MicroRNAs (miRNAs) and trans-acting small-interfering RNAs (tasi-RNAs) are small (20–22 nt long) RNAs (smRNAs) generated from hairpin secondary structures or antisense transcripts, respectively, that regulate gene expression by Watson-Crick pairing to a target mRNA and altering expression by mechanisms related to RNA interference. The high sequence homology of plant miRNAs to their targets has been the mainstay of miRNA prediction algorithms, which are limited in their predictive power for other kingdoms because miRNA complementarity is less conserved yet transitive processes (production of antisense smRNAs) are active in eukaryotes. We hypothesize that antisense transcription and associated smRNAs are biomarkers which can be computationally modeled for gene discovery. Principal Findings We explored rice (Oryza sativa) sense and antisense gene expression in publicly available whole genome tiling array transcriptome data and sequenced smRNA libraries (as well as C. elegans) and found evidence of transitivity of MIRNA genes similar to that found in Arabidopsis. Statistical analysis of antisense transcript abundances, presence of antisense ESTs, and association with smRNAs suggests several hundred Arabidopsis ‘orphan’ hypothetical genes are non-coding RNAs. Consistent with this hypothesis, we found novel Arabidopsis homologues of some MIRNA genes on the antisense strand of previously annotated protein-coding genes. A Support Vector Machine (SVM) was applied using thermodynamic energy of binding plus novel expression features of sense/antisense transcription topology and siRNA abundances to build a prediction model of miRNA targets. The SVM when trained on targets could predict the “ancient” (deeply conserved) class of validated Arabidopsis MIRNA genes with an accuracy of 84%, and 76% for “new” rapidly-evolving MIRNA genes. Conclusions Antisense and smRNA expression features and computational methods may identify novel MIRNA genes and other non-coding RNAs in plants and potentially other kingdoms, which can provide insight into antisense transcription, miRNA evolution, and post-transcriptional gene regulation. PMID:20520764

Maintenance of CCL5 mRNA stores by post-effector and memory CD8 T cells is dependent on transcription and is coupled to increased mRNA stability.

PubMed

Marçais, Antoine; Tomkowiak, Martine; Walzer, Thierry; Coupet, Charles-Antoine; Ravel-Chapuis, Aymeric; Marvel, Jacqueline

2006-10-01

Immunological memory is associated with the display of improved effector functions by cells of the adaptive immune system. The storage of untranslated mRNA coding for the CCL5 chemokine by CD8 memory cells is a new process supporting the immediate display of an effector function. Here, we show that, after induction during the primary response, high CCL5 mRNA levels are specifically preserved in CD8 T cells. We have investigated the mechanisms involved in the long-term maintenance of CCL5 mRNA levels by memory CD8 T cells. We demonstrate that the CCL5 mRNA half-life is increased in memory CD8 T cells and that these cells constitutively transcribe ccl5 gene. By inhibiting ccl5 transcription using IL-4, we demonstrate the essential role of transcription in the maintenance of CCL5 mRNA stores. Finally, we show that these stores are spontaneously reconstituted when the inhibitory signal is removed, indicating that the transcription of ccl5 is a default feature of memory CD8 T cells imprinted in their genetic program.

Identification and characterization of a class of MALAT1 -like genomic loci

DOE PAGES

Zhang, Bin; Mao, Yuntao S.; Diermeier, Sarah D.; ...

2017-05-23

The MALAT1 (Metastasis-Associated Lung Adenocarcinoma Transcript 1) gene encodes a noncoding RNA that is processed into a long nuclear retained transcript ( MALAT1) and a small cytoplasmic tRNA-like transcript (mascRNA). Using an RNA sequence- and structure-based covariance model, we identified more than 130 genomic loci in vertebrate genomes containing the MALAT1 3' end triple-helix structure and its immediate downstream tRNA-like structure, including 44 in the green lizard Anolis carolinensis. Structural and computational analyses revealed a co-occurrence of components of the 3' end module. MALAT1-like genes in Anolis carolinensis are highly expressed in adult testis, thus we named them testis-abundant longmore » noncoding RNAs (tancRNAs). MALAT1-like loci also produce multiple small RNA species, including PIWI-interacting RNAs (piRNAs), from the antisense strand. The 3' ends of tancRNAs serve as potential targets for the PIWI-piRNA complex. Furthermore, we have identified an evolutionarily conserved class of long noncoding RNAs (lncRNAs) with similar structural constraints, post-transcriptional processing, and subcellular localization and a distinct function in spermatocytes.« less

Identification and characterization of a class of MALAT1 -like genomic loci

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Bin; Mao, Yuntao S.; Diermeier, Sarah D.

The MALAT1 (Metastasis-Associated Lung Adenocarcinoma Transcript 1) gene encodes a noncoding RNA that is processed into a long nuclear retained transcript ( MALAT1) and a small cytoplasmic tRNA-like transcript (mascRNA). Using an RNA sequence- and structure-based covariance model, we identified more than 130 genomic loci in vertebrate genomes containing the MALAT1 3' end triple-helix structure and its immediate downstream tRNA-like structure, including 44 in the green lizard Anolis carolinensis. Structural and computational analyses revealed a co-occurrence of components of the 3' end module. MALAT1-like genes in Anolis carolinensis are highly expressed in adult testis, thus we named them testis-abundant longmore » noncoding RNAs (tancRNAs). MALAT1-like loci also produce multiple small RNA species, including PIWI-interacting RNAs (piRNAs), from the antisense strand. The 3' ends of tancRNAs serve as potential targets for the PIWI-piRNA complex. Furthermore, we have identified an evolutionarily conserved class of long noncoding RNAs (lncRNAs) with similar structural constraints, post-transcriptional processing, and subcellular localization and a distinct function in spermatocytes.« less

Riboregulation of the bacterial actin-homolog MreB by DsrA small noncoding RNA.

PubMed

Cayrol, Bastien; Fortas, Emilie; Martret, Claire; Cech, Grzegorz; Kloska, Anna; Caulet, Stephane; Barbet, Marion; Trépout, Sylvain; Marco, Sergio; Taghbalout, Aziz; Busi, Florent; Wegrzyn, Grzegorz; Arluison, Véronique

2015-01-01

The bacterial actin-homolog MreB is a key player in bacterial cell-wall biosynthesis and is required for the maintenance of the rod-like morphology of Escherichia coli. However, how MreB cellular levels are adjusted to growth conditions is poorly understood. Here, we show that DsrA, an E. coli small noncoding RNA (sRNA), is involved in the post-transcriptional regulation of mreB. DsrA is required for the downregulation of MreB cellular concentration during environmentally induced slow growth-rates, mainly growth at low temperature and during the stationary phase. DsrA interacts in an Hfq-dependent manner with the 5' region of mreB mRNA, which contains signals for translation initiation and thereby affects mreB translation and stability. Moreover, as DsrA is also involved in the regulation of two transcriptional regulators, σ(S) and the nucleoid associated protein H-NS, which negatively regulate mreB transcription, it also indirectly contributes to mreB transcriptional down-regulation. By using quantitative analyses, our results evidence the complexity of this regulation and the tangled interplay between transcriptional and post-transcriptional control. As transcription factors and sRNA-mediated post-transcriptional regulators use different timescales, we propose that the sRNA pathway helps to adapt to changes in temperature, but also indirectly mediates long-term regulation of MreB concentration. The tight regulation and fine-tuning of mreB gene expression in response to cellular stresses is discussed in regard to the effect of the MreB protein on cell elongation.

Repression of TFIIH Transcriptional Activity and TFIIH-Associated cdk7 Kinase Activity at Mitosis

PubMed Central

Long, John J.; Leresche, Anne; Kriwacki, Richard W.; Gottesfeld, Joel M.

1998-01-01

Nuclear transcription is repressed when eukaryotic cells enter mitosis. Mitotic repression of transcription of various cellular and viral gene promoters by RNA polymerase II can be reproduced in vitro either with extracts prepared from cells arrested at mitosis with the microtubule polymerization inhibitor nocodazole or with nuclear extracts prepared from asynchronous cells and the mitotic protein kinase cdc2/cyclin B. Purified cdc2/cyclin B kinase is also sufficient to inhibit transcription in reconstituted transcription reactions with biochemically purified and recombinant basal transcription factors and RNA polymerase II. The cyclin-dependent kinase inhibitor p21Waf1/Cip1/Sdi1 can reverse the effect of cdc2/cyclin B kinase, indicating that repression of transcription is due to protein phosphorylation. Transcription rescue and inhibition experiments with each of the basal factors and the polymerase suggest that multiple components of the transcription machinery are inactivated by cdc2/cyclin B kinase. For an activated promoter, targets of repression are TFIID and TFIIH, while for a basal promoter, TFIIH is the major target for mitotic inactivation of transcription. Protein labeling experiments indicate that the p62 and p36 subunits of TFIIH are in vitro substrates for mitotic phosphorylation. Using the carboxy-terminal domain of the large subunit of RNA polymerase II as a test substrate for phosphorylation, the TFIIH-associated kinase, cdk7/cyclin H, is inhibited concomitant with inhibition of transcription activity. Our results suggest that there exist multiple phosphorylation targets for the global shutdown of transcription at mitosis. PMID:9488463

Enhancement of single guide RNA transcription for efficient CRISPR/Cas-based genomic engineering.

PubMed

Ui-Tei, Kumiko; Maruyama, Shohei; Nakano, Yuko

2017-06-01

Genomic engineering using clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) protein is a promising approach for targeting the genomic DNA of virtually any organism in a sequence-specific manner. Recent remarkable advances in CRISPR/Cas technology have made it a feasible system for use in therapeutic applications and biotechnology. In the CRISPR/Cas system, a guide RNA (gRNA), interacting with the Cas protein, recognizes a genomic region with sequence complementarity, and the double-stranded DNA at the target site is cleaved by the Cas protein. A widely used gRNA is an RNA polymerase III (pol III)-driven single gRNA (sgRNA), which is produced by artificial fusion of CRISPR RNA (crRNA) and trans-activation crRNA (tracrRNA). However, we identified a TTTT stretch, known as a termination signal of RNA pol III, in the scaffold region of the sgRNA. Here, we revealed that sgRNA carrying a TTTT stretch reduces the efficiency of sgRNA transcription due to premature transcriptional termination, and decreases the efficiency of genome editing. Unexpectedly, it was also shown that the premature terminated sgRNA may have an adverse effect of inducing RNA interference. Such disadvantageous effects were avoided by substituting one base in the TTTT stretch.

Psmir: a database of potential associations between small molecules and miRNAs

PubMed Central

Meng, Fanlin; Wang, Jing; Dai, Enyu; Yang, Feng; Chen, Xiaowen; Wang, Shuyuan; Yu, Xuexin; Liu, Dianming; Jiang, Wei

2016-01-01

miRNAs are key post-transcriptional regulators of many essential biological processes, and their dysregulation has been validated in almost all human cancers. Restoring aberrantly expressed miRNAs might be a novel therapeutics. Recently, many studies have demonstrated that small molecular compounds can affect miRNA expression. Thus, prediction of associations between small molecules and miRNAs is important for investigation of miRNA-targeted drugs. Here, we analyzed 39 miRNA-perturbed gene expression profiles, and then calculated the similarity of transcription responses between miRNA perturbation and drug treatment to predict drug-miRNA associations. At the significance level of 0.05, we obtained 6501 candidate associations between 1295 small molecules and 25 miRNAs, which included 624 FDA approved drugs. Finally, we constructed the Psmir database to store all potential associations and the related materials. In a word, Psmir served as a valuable resource for dissecting the biological significance in small molecules’ effects on miRNA expression, which will facilitate developing novel potential therapeutic targets or treatments for human cancers. Psmir is supported by all major browsers, and is freely available at http://www.bio-bigdata.com/Psmir/. PMID:26759061

Psmir: a database of potential associations between small molecules and miRNAs.

PubMed

Meng, Fanlin; Wang, Jing; Dai, Enyu; Yang, Feng; Chen, Xiaowen; Wang, Shuyuan; Yu, Xuexin; Liu, Dianming; Jiang, Wei

2016-01-13

miRNAs are key post-transcriptional regulators of many essential biological processes, and their dysregulation has been validated in almost all human cancers. Restoring aberrantly expressed miRNAs might be a novel therapeutics. Recently, many studies have demonstrated that small molecular compounds can affect miRNA expression. Thus, prediction of associations between small molecules and miRNAs is important for investigation of miRNA-targeted drugs. Here, we analyzed 39 miRNA-perturbed gene expression profiles, and then calculated the similarity of transcription responses between miRNA perturbation and drug treatment to predict drug-miRNA associations. At the significance level of 0.05, we obtained 6501 candidate associations between 1295 small molecules and 25 miRNAs, which included 624 FDA approved drugs. Finally, we constructed the Psmir database to store all potential associations and the related materials. In a word, Psmir served as a valuable resource for dissecting the biological significance in small molecules' effects on miRNA expression, which will facilitate developing novel potential therapeutic targets or treatments for human cancers. Psmir is supported by all major browsers, and is freely available at http://www.bio-bigdata.com/Psmir/.

Glucose-Regulated Phosphorylation of the PUF Protein Puf3 Regulates the Translational Fate of Its Bound mRNAs and Association with RNA Granules.

PubMed

Lee, Chien-Der; Tu, Benjamin P

2015-06-16

PUF proteins are post-transcriptional regulators that bind to the 3' UTRs of mRNA transcripts. Herein, we show how a yeast PUF protein, Puf3p, responds to glucose availability to switch the fate of its bound transcripts that encode proteins required for mitochondrial biogenesis. Upon glucose depletion, Puf3p becomes heavily phosphorylated within its N-terminal region of low complexity, associates with polysomes, and promotes translation of its target mRNAs. Such nutrient-responsive phosphorylation toggles the activity of Puf3p to promote either degradation or translation of these mRNAs according to the needs of the cell. Moreover, activation of translation of pre-existing mRNAs might enable rapid adjustment to environmental changes without the need for de novo transcription. Strikingly, a Puf3p phosphomutant no longer promotes translation but becomes trapped in intracellular foci in an mRNA-dependent manner. Our findings suggest that the inability to properly resolve Puf3p-containing RNA-protein granules via a phosphorylation-based mechanism might be toxic to a cell. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Overexpression of a natural chloroplast-encoded antisense RNA in tobacco destabilizes 5S rRNA and retards plant growth.

PubMed

Hotto, Amber M; Huston, Zoe E; Stern, David B

2010-09-29

The roles of non-coding RNAs in regulating gene expression have been extensively studied in both prokaryotes and eukaryotes, however few reports exist as to their roles in organellar gene regulation. Evidence for accumulation of natural antisense RNAs (asRNAs) in chloroplasts comes from the expressed sequence tag database and cDNA libraries, while functional data have been largely obtained from artificial asRNAs. In this study, we used Nicotiana tabacum to investigate the effect on sense strand transcripts of overexpressing a natural chloroplast asRNA, AS5, which is complementary to the region which encodes the 5S rRNA and tRNAArg. AS5-overexpressing (AS5ox) plants obtained by chloroplast transformation exhibited slower growth and slightly pale green leaves. Analysis of AS5 transcripts revealed four distinct species in wild-type (WT) and AS5ox plants, and additional AS5ox-specific products. Of the corresponding sense strand transcripts, tRNAArg overaccumulated several-fold in transgenic plants whereas 5S rRNA was unaffected. However, run-on transcription showed that the 5S-trnR region was transcribed four-fold more in the AS5ox plants compared to WT, indicating that overexpression of AS5 was associated with decreased stability of 5S rRNA. In addition, polysome analysis of the transformants showed less 5S rRNA and rbcL mRNA associated with ribosomes. Our results suggest that AS5 can modulate 5S rRNA levels, giving it the potential to affect Chloroplast translation and plant growth. More globally, overexpression of asRNAs via chloroplast transformation may be a useful strategy for defining their functions.

TIF-IC, a factor involved in both transcription initiation and elongation of RNA polymerase I.

PubMed Central

Schnapp, G; Schnapp, A; Rosenbauer, H; Grummt, I

1994-01-01

We have characterized a transcription factor from Ehrlich ascites cells that is required for ribosomal gene transcription by RNA polymerase I (Pol I). This factor, termed TIF-IC, has a native molecular mass of 65 kDa, associates with Pol I, and is required both for the assembly of Sarkosyl-resistant initiation complexes and for the formation of the first internucleotide bonds. In addition to its function in transcription initiation, TIF-IC also plays a role in elongation of nascent RNA chains. At suboptimal levels of TIF-IC, transcripts with heterogeneous 3' ends are formed which are chased into full-length transcripts by the addition of more TIF-IC. Moreover, on a tailed template, which allows initiation in the absence of auxiliary factors, TIF-IC was found to stimulate the overall rate of transcription elongation and suppress pausing of Pol I. Thus TIF-IC appears to serve a function similar to the Pol II-specific factor TFIIF which is required for Pol II transcription initiation and elongation. Images PMID:8076598

Rrp6 is recruited to transcribed genes and accompanies the spliced mRNA to the nuclear pore

PubMed Central

Hessle, Viktoria; von Euler, Anne; González de Valdivia, Ernesto; Visa, Neus

2012-01-01

Rrp6 is an exoribonuclease involved in the quality control of mRNA biogenesis. We have analyzed the association of Rrp6 with the Balbiani ring pre-mRNPs of Chironomus tentans to obtain insight into the role of Rrp6 in splicing surveillance. Rrp6 is recruited to transcribed genes and its distribution along the genes does not correlate with the positions of exons and introns. In the nucleoplasm, Rrp6 is bound to both unspliced and spliced transcripts. Rrp6 is released from the mRNPs in the vicinity of the nuclear pore before nucleo-cytoplasmic translocation. We show that Rrp6 is associated with newly synthesized transcripts during all the nuclear steps of gene expression and is associated with the transcripts independently of their splicing status. These observations suggest that the quality control of pre-mRNA splicing is not based on the selective recruitment of the exoribonuclease Rrp6 to unprocessed mRNAs. PMID:22745224

Molecular characterization of 5S ribosomal RNA genes and transcripts in the protozoan parasite Leishmania major.

PubMed

Moreno-Campos, Rodrigo; Florencio-Martínez, Luis E; Nepomuceno-Mejía, Tomás; Rojas-Sánchez, Saúl; Vélez-Ramírez, Daniel E; Padilla-Mejía, Norma E; Figueroa-Angulo, Elisa; Manning-Cela, Rebeca; Martínez-Calvillo, Santiago

2016-12-01

Eukaryotic 5S rRNA, synthesized by RNA polymerase III (Pol III), is an essential component of the large ribosomal subunit. Most organisms contain hundreds of 5S rRNA genes organized into tandem arrays. However, the genome of the protozoan parasite Leishmania major contains only 11 copies of the 5S rRNA gene, which are interspersed and associated with other Pol III-transcribed genes. Here we report that, in general, the number and order of the 5S rRNA genes is conserved between different species of Leishmania. While in most organisms 5S rRNA genes are normally associated with the nucleolus, combined fluorescent in situ hybridization and indirect immunofluorescence experiments showed that 5S rRNA genes are mainly located at the nuclear periphery in L. major. Similarly, the tandemly repeated 5S rRNA genes in Trypanosoma cruzi are dispersed throughout the nucleus. In contrast, 5S rRNA transcripts in L. major were localized within the nucleolus, and scattered throughout the cytoplasm, where mature ribosomes are located. Unlike other rRNA species, stable antisense RNA complementary to 5S rRNA is not detected in L. major.

New discoveries linking transcription to DNA repair and damage tolerance pathways.

PubMed

Cohen, Susan E; Walker, Graham C

2011-01-01

In Escherichia coli, the transcription elongation factor NusA is associated with all elongating RNA polymerases where it functions in transcription termination and antitermination. Here, we review our recent results implicating NusA in the recruitment of DNA repair and damage tolerance mechanisms to sites of stalled transcription complexes.

Zinc Finger-Containing Cellular Transcription Corepressor ZBTB25 Promotes Influenza Virus RNA Transcription and Is a Target for Zinc Ejector Drugs.

PubMed

Chen, Shu-Chuan; Jeng, King-Song; Lai, Michael M C

2017-10-15

Influenza A virus (IAV) replication relies on an intricate interaction between virus and host cells. How the cellular proteins are usurped for IAV replication remains largely obscure. The aim of this study was to search for novel and potential cellular factors that participate in IAV replication. ZBTB25, a transcription repressor of a variety of cellular genes, was identified by an RNA interference (RNAi) genomic library screen. Depletion of ZBTB25 significantly reduced IAV production. Conversely, overexpression of ZBTB25 enhanced it. ZBTB25 interacted with the viral RNA-dependent RNA polymerase (RdRp) protein and modulated its transcription activity. In addition, ZBTB25 also functioned as a viral RNA (vRNA)-binding protein, binding preferentially to the U-rich sequence within the 5' untranslated region (UTR) of vRNA. Both protein-protein and protein-RNA interactions involving ZBTB25 facilitated viral RNA transcription and replication. In addition, ZBTB25 suppressed interferon production, further enhancing viral replication. ZBTB25-associated functions required an intact zinc finger domain and posttranslational SUMO-1 modification of ZBTB25. Furthermore, treatment with disulfiram (a zinc ejector) of ZBTB25-overexpressing cells showed significantly reduced IAV production as a result of reduced RNA synthesis. Our findings indicate that IAV usurps ZBTB25 for IAV RNA synthesis and serves as a novel and potential therapeutic antiviral target. IMPORTANCE IAV-induced seasonal influenza causes severe illness and death in high-risk populations. However, IAV has developed resistance to current antiviral drugs due to its high mutation rate. Therefore, development of drugs targeting cellular factors required for IAV replication is an attractive alternative for IAV therapy. Here, we discovered a cellular protein, ZBTB25, that enhances viral RdRp activity by binding to both viral RdRp and viral RNA to stimulate viral RNA synthesis. A unique feature of ZBTB25 in the regulation of viral replication is its dual transcription functions, namely, promoting viral RNA transcription through binding to the U-rich region of vRNA and suppressing cellular interferon production. ZBTB25 contains a zinc finger domain that is required for RNA-inhibitory activity by chelating zinc ions. Disulfiram treatment disrupts the zinc finger functions, effectively repressing IAV replication. Based on our findings, we demonstrate that ZBTB25 regulates IAV RNA transcription and replication and serves as a promising antiviral target for IAV treatment. Copyright © 2017 American Society for Microbiology.

Zinc Finger-Containing Cellular Transcription Corepressor ZBTB25 Promotes Influenza Virus RNA Transcription and Is a Target for Zinc Ejector Drugs

PubMed Central

Chen, Shu-Chuan; Jeng, King-Song

2017-01-01

ABSTRACT Influenza A virus (IAV) replication relies on an intricate interaction between virus and host cells. How the cellular proteins are usurped for IAV replication remains largely obscure. The aim of this study was to search for novel and potential cellular factors that participate in IAV replication. ZBTB25, a transcription repressor of a variety of cellular genes, was identified by an RNA interference (RNAi) genomic library screen. Depletion of ZBTB25 significantly reduced IAV production. Conversely, overexpression of ZBTB25 enhanced it. ZBTB25 interacted with the viral RNA-dependent RNA polymerase (RdRp) protein and modulated its transcription activity. In addition, ZBTB25 also functioned as a viral RNA (vRNA)-binding protein, binding preferentially to the U-rich sequence within the 5′ untranslated region (UTR) of vRNA. Both protein-protein and protein-RNA interactions involving ZBTB25 facilitated viral RNA transcription and replication. In addition, ZBTB25 suppressed interferon production, further enhancing viral replication. ZBTB25-associated functions required an intact zinc finger domain and posttranslational SUMO-1 modification of ZBTB25. Furthermore, treatment with disulfiram (a zinc ejector) of ZBTB25-overexpressing cells showed significantly reduced IAV production as a result of reduced RNA synthesis. Our findings indicate that IAV usurps ZBTB25 for IAV RNA synthesis and serves as a novel and potential therapeutic antiviral target. IMPORTANCE IAV-induced seasonal influenza causes severe illness and death in high-risk populations. However, IAV has developed resistance to current antiviral drugs due to its high mutation rate. Therefore, development of drugs targeting cellular factors required for IAV replication is an attractive alternative for IAV therapy. Here, we discovered a cellular protein, ZBTB25, that enhances viral RdRp activity by binding to both viral RdRp and viral RNA to stimulate viral RNA synthesis. A unique feature of ZBTB25 in the regulation of viral replication is its dual transcription functions, namely, promoting viral RNA transcription through binding to the U-rich region of vRNA and suppressing cellular interferon production. ZBTB25 contains a zinc finger domain that is required for RNA-inhibitory activity by chelating zinc ions. Disulfiram treatment disrupts the zinc finger functions, effectively repressing IAV replication. Based on our findings, we demonstrate that ZBTB25 regulates IAV RNA transcription and replication and serves as a promising antiviral target for IAV treatment. PMID:28768860

Regulating infidelity: RNA-mediated recruitment of AID to DNA during class switch recombination.

PubMed

DiMenna, Lauren J; Chaudhuri, Jayanta

2016-03-01

The mechanism by which the DNA deaminase activation-induced cytidine deaminase (AID) is specifically recruited to repetitive switch region DNA during class switch recombination is still poorly understood. Work over the past decade has revealed a strong link between transcription and RNA polymerase-associated factors in AID recruitment, yet none of these processes satisfactorily explain how AID specificity is affected. Here, we review a recent finding wherein AID is guided to switch regions not by a protein factor but by an RNA moiety, and especially one associated with a noncoding RNA that has been long thought of as being inert. This work explains the long-standing requirement of splicing of noncoding transcripts during class switching, and has implications in both B cell-mediated immunity as well as the underlying pathological syndromes associated with the recombination reaction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Compensatory Evolution of Intrinsic Transcription Terminators in Bacillus Cereus

PubMed Central

Safina, Ksenia R.; Mironov, Andrey A.

2017-01-01

Many RNA molecules possess complicated secondary structure critical to their function. Mutations in double-helical regions of RNA may disrupt Watson–Crick (WC) interactions causing structure destabilization or even complete loss of function. Such disruption can be compensated by another mutation restoring base pairing, as has been shown for mRNA, rRNA and tRNA. Here, we investigate the evolution of intrinsic transcription terminators between closely related strains of Bacillus cereus. While the terminator structure is maintained by strong natural selection, as evidenced by the low frequency of disrupting mutations, we observe multiple instances of pairs of disrupting-compensating mutations in RNA structure stems. Such two-step switches between different WC pairs occur very fast, consistent with the low fitness conferred by the intermediate non-WC variant. Still, they are not instantaneous, and probably involve transient fixation of the intermediate variant. The GU wobble pair is the most frequent intermediate, and remains fixed longer than other intermediates, consistent with its less disruptive effect on the RNA structure. Double switches involving non-GU intermediates are more frequent at the ends of RNA stems, probably because they are associated with smaller fitness loss. Together, these results show that the fitness landscape of bacterial transcription terminators is rather rugged, but that the fitness valleys associated with unpaired stem nucleotides are rather shallow, facilitating evolution. PMID:28201729

Coronary heart disease-associated variation in TCF21 disrupts a miR-224 binding site and miRNA-mediated regulation.

PubMed

Miller, Clint L; Haas, Ulrike; Diaz, Roxanne; Leeper, Nicholas J; Kundu, Ramendra K; Patlolla, Bhagat; Assimes, Themistocles L; Kaiser, Frank J; Perisic, Ljubica; Hedin, Ulf; Maegdefessel, Lars; Schunkert, Heribert; Erdmann, Jeanette; Quertermous, Thomas; Sczakiel, Georg

2014-03-01

Genome-wide association studies (GWAS) have identified chromosomal loci that affect risk of coronary heart disease (CHD) independent of classical risk factors. One such association signal has been identified at 6q23.2 in both Caucasians and East Asians. The lead CHD-associated polymorphism in this region, rs12190287, resides in the 3' untranslated region (3'-UTR) of TCF21, a basic-helix-loop-helix transcription factor, and is predicted to alter the seed binding sequence for miR-224. Allelic imbalance studies in circulating leukocytes and human coronary artery smooth muscle cells (HCASMC) showed significant imbalance of the TCF21 transcript that correlated with genotype at rs12190287, consistent with this variant contributing to allele-specific expression differences. 3' UTR reporter gene transfection studies in HCASMC showed that the disease-associated C allele has reduced expression compared to the protective G allele. Kinetic analyses in vitro revealed faster RNA-RNA complex formation and greater binding of miR-224 with the TCF21 C allelic transcript. In addition, in vitro probing with Pb2+ and RNase T1 revealed structural differences between the TCF21 variants in proximity of the rs12190287 variant, which are predicted to provide greater access to the C allele for miR-224 binding. miR-224 and TCF21 expression levels were anti-correlated in HCASMC, and miR-224 modulates the transcriptional response of TCF21 to transforming growth factor-β (TGF-β) and platelet derived growth factor (PDGF) signaling in an allele-specific manner. Lastly, miR-224 and TCF21 were localized in human coronary artery lesions and anti-correlated during atherosclerosis. Together, these data suggest that miR-224 interaction with the TCF21 transcript contributes to allelic imbalance of this gene, thus partly explaining the genetic risk for coronary heart disease associated at 6q23.2. These studies implicating rs12190287 in the miRNA-dependent regulation of TCF21, in conjunction with previous studies showing that this variant modulates transcriptional regulation through activator protein 1 (AP-1), suggests a unique bimodal level of complexity previously unreported for disease-associated variants.

Regulation of miRNA Processing and miRNA Mediated Gene Repression in Cancer

PubMed Central

Bajan, Sarah; Hutvagner, Gyorgy

2014-01-01

The majority of human protein-coding genes are predicted to be targets of miRNA-mediated post-transcriptional regulation. The widespread influence of miRNAs is illustrated by their essential roles in all biological processes. Regulated miRNA expression is essential for maintaining cellular differentiation; therefore alterations in miRNA expression patterns are associated with several diseases, including various cancers. High-throughput sequencing technologies revealed low level expressing miRNA isoforms, termed isomiRs. IsomiRs may differ in sequence, length, target preference and expression patterns from their parental miRNA and can arise from differences in miRNA biosynthesis, RNA editing, or SNPs inherent to the miRNA gene. The association between isomiR expression and disease progression is largely unknown. Misregulated miRNA expression is thought to contribute to the formation and/or progression of cancer. However, due to the diversity of targeted transcripts, miRNAs can function as both tumor-suppressor genes and oncogenes as defined by cellular context. Despite this, miRNA profiling studies concluded that the differential expression of particular miRNAs in diseased tissue could aid the diagnosis and treatment of some cancers. PMID:25069508

Inventory of high-abundance mRNAs in skeletal muscle of normal men.

PubMed

Welle, S; Bhatt, K; Thornton, C A

1999-05-01

G42875rial analysis of gene expression (SAGE) method was used to generate a catalog of 53,875 short (14 base) expressed sequence tags from polyadenylated RNA obtained from vastus lateralis muscle of healthy young men. Over 12,000 unique tags were detected. The frequency of occurrence of each tag reflects the relative abundance of the corresponding mRNA. The mRNA species that were detected 10 or more times, each comprising >/=0.02% of the mRNA population, accounted for 64% of the mRNA mass but <10% of the total number of mRNA species detected. Almost all of the abundant tags matched mRNA or EST sequences cataloged in GenBank. Mitochondrial transcripts accounted for approximately 20% of the polyadenylated RNA. Transcripts encoding proteins of the myofibrils were the most abundant nuclear-encoded mRNAs. Transcripts encoding ribosomal proteins, and those encoding proteins involved in energy metabolism, also were very abundant. The database can be used as a reference for investigations of alterations in gene expression associated with conditions that influence muscle function, such as muscular dystrophies, aging, and exercise.

Inference of RNA decay rate from transcriptional profiling highlights the regulatory programs of Alzheimer's disease.

PubMed

Alkallas, Rached; Fish, Lisa; Goodarzi, Hani; Najafabadi, Hamed S

2017-10-13

The abundance of mRNA is mainly determined by the rates of RNA transcription and decay. Here, we present a method for unbiased estimation of differential mRNA decay rate from RNA-sequencing data by modeling the kinetics of mRNA metabolism. We show that in all primary human tissues tested, and particularly in the central nervous system, many pathways are regulated at the mRNA stability level. We present a parsimonious regulatory model consisting of two RNA-binding proteins and four microRNAs that modulate the mRNA stability landscape of the brain, which suggests a new link between RBFOX proteins and Alzheimer's disease. We show that downregulation of RBFOX1 leads to destabilization of mRNAs encoding for synaptic transmission proteins, which may contribute to the loss of synaptic function in Alzheimer's disease. RBFOX1 downregulation is more likely to occur in older and female individuals, consistent with the association of Alzheimer's disease with age and gender."mRNA abundance is determined by the rates of transcription and decay. Here, the authors propose a method for estimating the rate of differential mRNA decay from RNA-seq data and model mRNA stability in the brain, suggesting a link between mRNA stability and Alzheimer's disease."

Novel kinase fusion transcripts found in endometrial cancer

PubMed Central

Tamura, Ryo; Yoshihara, Kosuke; Yamawaki, Kaoru; Suda, Kazuaki; Ishiguro, Tatsuya; Adachi, Sosuke; Okuda, Shujiro; Inoue, Ituro; Verhaak, Roel G. W.; Enomoto, Takayuki

2015-01-01

Recent advances in RNA-sequencing technology have enabled the discovery of gene fusion transcripts in the transcriptome of cancer cells. However, it remains difficult to differentiate the therapeutically targetable fusions from passenger events. We have analyzed RNA-sequencing data and DNA copy number data from 25 endometrial cancer cell lines to identify potential therapeutically targetable fusion transcripts, and have identified 124 high-confidence fusion transcripts, of which 69% are associated with gene amplifications. As targetable fusion candidates, we focused on three in-frame kinase fusion transcripts that retain a kinase domain (CPQ-PRKDC, CAPZA2-MET, and VGLL4-PRKG1). We detected only CPQ-PRKDC fusion transcript in three of 122 primary endometrial cancer tissues. Cell proliferation of the fusion-positive cell line was inhibited by knocking down the expression of wild-type PRKDC but not by blocking the CPQ-PRKDC fusion transcript expression. Quantitative real-time RT-PCR demonstrated that the expression of the CPQ-PRKDC fusion transcript was significantly lower than that of wild-type PRKDC, corresponding to a low transcript allele fraction of this fusion, based on RNA-sequencing read counts. In endometrial cancers, the CPQ-PRKDC fusion transcript may be a passenger aberration related to gene amplification. Our findings suggest that transcript allele fraction is a useful predictor to find bona-fide therapeutic-targetable fusion transcripts. PMID:26689674

Novel kinase fusion transcripts found in endometrial cancer.

PubMed

Tamura, Ryo; Yoshihara, Kosuke; Yamawaki, Kaoru; Suda, Kazuaki; Ishiguro, Tatsuya; Adachi, Sosuke; Okuda, Shujiro; Inoue, Ituro; Verhaak, Roel G W; Enomoto, Takayuki

2015-12-22

Recent advances in RNA-sequencing technology have enabled the discovery of gene fusion transcripts in the transcriptome of cancer cells. However, it remains difficult to differentiate the therapeutically targetable fusions from passenger events. We have analyzed RNA-sequencing data and DNA copy number data from 25 endometrial cancer cell lines to identify potential therapeutically targetable fusion transcripts, and have identified 124 high-confidence fusion transcripts, of which 69% are associated with gene amplifications. As targetable fusion candidates, we focused on three in-frame kinase fusion transcripts that retain a kinase domain (CPQ-PRKDC, CAPZA2-MET, and VGLL4-PRKG1). We detected only CPQ-PRKDC fusion transcript in three of 122 primary endometrial cancer tissues. Cell proliferation of the fusion-positive cell line was inhibited by knocking down the expression of wild-type PRKDC but not by blocking the CPQ-PRKDC fusion transcript expression. Quantitative real-time RT-PCR demonstrated that the expression of the CPQ-PRKDC fusion transcript was significantly lower than that of wild-type PRKDC, corresponding to a low transcript allele fraction of this fusion, based on RNA-sequencing read counts. In endometrial cancers, the CPQ-PRKDC fusion transcript may be a passenger aberration related to gene amplification. Our findings suggest that transcript allele fraction is a useful predictor to find bona-fide therapeutic-targetable fusion transcripts.

Dual Analysis of the Murine Cytomegalovirus and Host Cell Transcriptomes Reveal New Aspects of the Virus-Host Cell Interface

PubMed Central

Juranic Lisnic, Vanda; Babic Cac, Marina; Lisnic, Berislav; Trsan, Tihana; Mefferd, Adam; Das Mukhopadhyay, Chitrangada; Cook, Charles H.; Jonjic, Stipan; Trgovcich, Joanne

2013-01-01

Major gaps in our knowledge of pathogen genes and how these gene products interact with host gene products to cause disease represent a major obstacle to progress in vaccine and antiviral drug development for the herpesviruses. To begin to bridge these gaps, we conducted a dual analysis of Murine Cytomegalovirus (MCMV) and host cell transcriptomes during lytic infection. We analyzed the MCMV transcriptome during lytic infection using both classical cDNA cloning and sequencing of viral transcripts and next generation sequencing of transcripts (RNA-Seq). We also investigated the host transcriptome using RNA-Seq combined with differential gene expression analysis, biological pathway analysis, and gene ontology analysis. We identify numerous novel spliced and unspliced transcripts of MCMV. Unexpectedly, the most abundantly transcribed viral genes are of unknown function. We found that the most abundant viral transcript, recently identified as a noncoding RNA regulating cellular microRNAs, also codes for a novel protein. To our knowledge, this is the first viral transcript that functions both as a noncoding RNA and an mRNA. We also report that lytic infection elicits a profound cellular response in fibroblasts. Highly upregulated and induced host genes included those involved in inflammation and immunity, but also many unexpected transcription factors and host genes related to development and differentiation. Many top downregulated and repressed genes are associated with functions whose roles in infection are obscure, including host long intergenic noncoding RNAs, antisense RNAs or small nucleolar RNAs. Correspondingly, many differentially expressed genes cluster in biological pathways that may shed new light on cytomegalovirus pathogenesis. Together, these findings provide new insights into the molecular warfare at the virus-host interface and suggest new areas of research to advance the understanding and treatment of cytomegalovirus-associated diseases. PMID:24086132

RNA-Seq Differentiates Tumour and Host mRNA Expression Changes Induced by Treatment of Human Tumour Xenografts with the VEGFR Tyrosine Kinase Inhibitor Cediranib

PubMed Central

Bradford, James R.; Farren, Matthew; Powell, Steve J.; Runswick, Sarah; Weston, Susie L.; Brown, Helen; Delpuech, Oona; Wappett, Mark; Smith, Neil R.; Carr, T. Hedley; Dry, Jonathan R.; Gibson, Neil J.; Barry, Simon T.

2013-01-01

Pre-clinical models of tumour biology often rely on propagating human tumour cells in a mouse. In order to gain insight into the alignment of these models to human disease segments or investigate the effects of different therapeutics, approaches such as PCR or array based expression profiling are often employed despite suffering from biased transcript coverage, and a requirement for specialist experimental protocols to separate tumour and host signals. Here, we describe a computational strategy to profile transcript expression in both the tumour and host compartments of pre-clinical xenograft models from the same RNA sample using RNA-Seq. Key to this strategy is a species-specific mapping approach that removes the need for manipulation of the RNA population, customised sequencing protocols, or prior knowledge of the species component ratio. The method demonstrates comparable performance to species-specific RT-qPCR and a standard microarray platform, and allowed us to quantify gene expression changes in both the tumour and host tissue following treatment with cediranib, a potent vascular endothelial growth factor receptor tyrosine kinase inhibitor, including the reduction of multiple murine transcripts associated with endothelium or vessels, and an increase in genes associated with the inflammatory response in response to cediranib. In the human compartment, we observed a robust induction of hypoxia genes and a reduction in cell cycle associated transcripts. In conclusion, the study establishes that RNA-Seq can be applied to pre-clinical models to gain deeper understanding of model characteristics and compound mechanism of action, and to identify both tumour and host biomarkers. PMID:23840389

Microprocessor mediates transcriptional termination in long noncoding microRNA genes

PubMed Central

Dhir, Ashish; Dhir, Somdutta; Proudfoot, Nick J.; Jopling, Catherine L.

2015-01-01

MicroRNA (miRNA) play a major role in the post-transcriptional regulation of gene expression. Mammalian miRNA biogenesis begins with co-transcriptional cleavage of RNA polymerase II (Pol II) transcripts by the Microprocessor complex. While most miRNA are located within introns of protein coding genes, a substantial minority of miRNA originate from long non coding (lnc) RNA where transcript processing is largely uncharacterized. We show, by detailed characterization of liver-specific lnc-pri-miR-122 and genome-wide analysis in human cell lines, that most lnc-pri-miRNA do not use the canonical cleavage and polyadenylation (CPA) pathway, but instead use Microprocessor cleavage to terminate transcription. This Microprocessor inactivation leads to extensive transcriptional readthrough of lnc-pri-miRNA and transcriptional interference with downstream genes. Consequently we define a novel RNase III-mediated, polyadenylation-independent mechanism of Pol II transcription termination in mammalian cells. PMID:25730776

The Activation-Induced Assembly of an RNA/Protein Interactome Centered on the Splicing Factor U2AF2 Regulates Gene Expression in Human CD4 T Cells.

PubMed

Whisenant, Thomas C; Peralta, Eigen R; Aarreberg, Lauren D; Gao, Nina J; Head, Steven R; Ordoukhanian, Phillip; Williamson, Jamie R; Salomon, Daniel R

2015-01-01

Activation of CD4 T cells is a reaction to challenges such as microbial pathogens, cancer and toxins that defines adaptive immune responses. The roles of T cell receptor crosslinking, intracellular signaling, and transcription factor activation are well described, but the importance of post-transcriptional regulation by RNA-binding proteins (RBPs) has not been considered in depth. We describe a new model expanding and activating primary human CD4 T cells and applied this to characterizing activation-induced assembly of splicing factors centered on U2AF2. We immunoprecipitated U2AF2 to identify what mRNA transcripts were bound as a function of activation by TCR crosslinking and costimulation. In parallel, mass spectrometry revealed the proteins incorporated into the U2AF2-centered RNA/protein interactome. Molecules that retained interaction with the U2AF2 complex after RNAse treatment were designated as "central" interactome members (CIMs). Mass spectrometry also identified a second class of activation-induced proteins, "peripheral" interactome members (PIMs), that bound to the same transcripts but were not in physical association with U2AF2 or its partners. siRNA knockdown of two CIMs and two PIMs caused changes in activation marker expression, cytokine secretion, and gene expression that were unique to each protein and mapped to pathways associated with key aspects of T cell activation. While knocking down the PIM, SYNCRIP, impacts a limited but immunologically important set of U2AF2-bound transcripts, knockdown of U2AF1 significantly impairs assembly of the majority of protein and mRNA components in the activation-induced interactome. These results demonstrated that CIMs and PIMs, either directly or indirectly through RNA, assembled into activation-induced U2AF2 complexes and play roles in post-transcriptional regulation of genes related to cytokine secretion. These data suggest an additional layer of regulation mediated by the activation-induced assembly of RNA splicing interactomes that is important for understanding T cell activation.

The Activation-Induced Assembly of an RNA/Protein Interactome Centered on the Splicing Factor U2AF2 Regulates Gene Expression in Human CD4 T Cells

PubMed Central

Aarreberg, Lauren D.; Gao, Nina J.; Head, Steven R.; Ordoukhanian, Phillip; Williamson, Jamie R.; Salomon, Daniel R.

2015-01-01

Activation of CD4 T cells is a reaction to challenges such as microbial pathogens, cancer and toxins that defines adaptive immune responses. The roles of T cell receptor crosslinking, intracellular signaling, and transcription factor activation are well described, but the importance of post-transcriptional regulation by RNA-binding proteins (RBPs) has not been considered in depth. We describe a new model expanding and activating primary human CD4 T cells and applied this to characterizing activation-induced assembly of splicing factors centered on U2AF2. We immunoprecipitated U2AF2 to identify what mRNA transcripts were bound as a function of activation by TCR crosslinking and costimulation. In parallel, mass spectrometry revealed the proteins incorporated into the U2AF2-centered RNA/protein interactome. Molecules that retained interaction with the U2AF2 complex after RNAse treatment were designated as “central” interactome members (CIMs). Mass spectrometry also identified a second class of activation-induced proteins, “peripheral” interactome members (PIMs), that bound to the same transcripts but were not in physical association with U2AF2 or its partners. siRNA knockdown of two CIMs and two PIMs caused changes in activation marker expression, cytokine secretion, and gene expression that were unique to each protein and mapped to pathways associated with key aspects of T cell activation. While knocking down the PIM, SYNCRIP, impacts a limited but immunologically important set of U2AF2-bound transcripts, knockdown of U2AF1 significantly impairs assembly of the majority of protein and mRNA components in the activation-induced interactome. These results demonstrated that CIMs and PIMs, either directly or indirectly through RNA, assembled into activation-induced U2AF2 complexes and play roles in post-transcriptional regulation of genes related to cytokine secretion. These data suggest an additional layer of regulation mediated by the activation-induced assembly of RNA splicing interactomes that is important for understanding T cell activation. PMID:26641092

Global Profiling of hnRNP A2/B1-RNA Binding on Chromatin Highlights LncRNA Interactions.

PubMed

Nguyen, Eric D; Balas, Maggie M; Griffin, April M; Roberts, Justin T; Johnson, Aaron M

2018-06-23

Long noncoding RNAs (lncRNAs) often carry out their functions through associations with adaptor proteins. We recently identified heterogeneous ribonucleoprotein (hnRNP) A2/B1 as an adaptor of the human HOTAIR lncRNA. hnRNP A2 and B1 are splice isoforms of the same gene. The spliced version of HOTAIR preferentially associates with the B1 isoform, which we hypothesize contributes to RNA-RNA matching between HOTAIR and transcripts of target genes in breast cancer. Here we used enhanced cross-linking immunoprecipitation (eCLIP) to map the direct interactions between A2/B1 and RNA in breast cancer cells. Despite differing by only twelve amino acids, the A2 and B1 splice isoforms associate preferentially with distinct populations of RNA in vivo. Through cellular fractionation experiments we characterize the pattern of RNA association in chromatin, nucleoplasm, and cytoplasm. We find that a majority of interactions occur on chromatin, even those that do not contribute to co-transcriptional splicing. A2/B1 binding site locations on multiple RNAs hint at a contribution to the regulation and function of lncRNAs. Surprisingly, the strongest A2/B1 binding site occurs in a retained intron of HOTAIR, which interrupts an RNA-RNA interaction hotspot. In vitro eCLIP experiments highlight additional exonic B1 binding sites in HOTAIR which also surround the RNA-RNA interaction hotspot. Interestingly, a version of HOTAIR with the intron retained is still capable of making RNA-RNA interactions in vitro through the hotspot region. Our data further characterize the multiple functions of a repurposed splicing factor with isoform-biased interactions, and highlight that the majority of these functions occur on chromatin-associated RNA.

High-throughput detection of RNA processing in bacteria.

PubMed

Gill, Erin E; Chan, Luisa S; Winsor, Geoffrey L; Dobson, Neil; Lo, Raymond; Ho Sui, Shannan J; Dhillon, Bhavjinder K; Taylor, Patrick K; Shrestha, Raunak; Spencer, Cory; Hancock, Robert E W; Unrau, Peter J; Brinkman, Fiona S L

2018-03-27

Understanding the RNA processing of an organism's transcriptome is an essential but challenging step in understanding its biology. Here we investigate with unprecedented detail the transcriptome of Pseudomonas aeruginosa PAO1, a medically important and innately multi-drug resistant bacterium. We systematically mapped RNA cleavage and dephosphorylation sites that result in 5'-monophosphate terminated RNA (pRNA) using monophosphate RNA-Seq (pRNA-Seq). Transcriptional start sites (TSS) were also mapped using differential RNA-Seq (dRNA-Seq) and both datasets were compared to conventional RNA-Seq performed in a variety of growth conditions. The pRNA-Seq library revealed known tRNA, rRNA and transfer-messenger RNA (tmRNA) processing sites, together with previously uncharacterized RNA cleavage events that were found disproportionately near the 5' ends of transcripts associated with basic bacterial functions such as oxidative phosphorylation and purine metabolism. The majority (97%) of the processed mRNAs were cleaved at precise codon positions within defined sequence motifs indicative of distinct endonucleolytic activities. The most abundant of these motifs corresponded closely to an E. coli RNase E site previously established in vitro. Using the dRNA-Seq library, we performed an operon analysis and predicted 3159 potential TSS. A correlation analysis uncovered 105 antiparallel pairs of TSS that were separated by 18 bp from each other and were centered on single palindromic TAT(A/T)ATA motifs (likely - 10 promoter elements), suggesting that, consistent with previous in vitro experimentation, these sites can initiate transcription bi-directionally and may thus provide a novel form of transcriptional regulation. TSS and RNA-Seq analysis allowed us to confirm expression of small non-coding RNAs (ncRNAs), many of which are differentially expressed in swarming and biofilm formation conditions. This study uses pRNA-Seq, a method that provides a genome-wide survey of RNA processing, to study the bacterium Pseudomonas aeruginosa and discover extensive transcript processing not previously appreciated. We have also gained novel insight into RNA maturation and turnover as well as a potential novel form of transcription regulation. NOTE: All sequence data has been submitted to the NCBI sequence read archive. Accession numbers are as follows: [NCBI sequence read archive: SRX156386, SRX157659, SRX157660, SRX157661, SRX157683 and SRX158075]. The sequence data is viewable using Jbrowse on www.pseudomonas.com .

Relative expression of rRNA transcripts and 45S rDNA promoter methylation status are dysregulated in tumors in comparison with matched-normal tissues in breast cancer.

PubMed

Karahan, Gurbet; Sayar, Nilufer; Gozum, Gokcen; Bozkurt, Betul; Konu, Ozlen; Yulug, Isik G

2015-06-01

Ribosomal RNA (rRNA) expression, one of the most important factors regulating ribosome production, is primarily controlled by a CG-rich 45 S rDNA promoter. However, the DNA methylation state of the 45 S rDNA promoter, as well as its effect on rRNA gene expression in types of human cancers is controversial. In the present study we analyzed the methylation status of the rDNA promoter (-380 to +53 bp) as well as associated rRNA expression levels in breast cancer cell lines and breast tumor-normal tissue pairs. We found that the aforementioned regulatory region was extensively methylated (74-96%) in all cell lines and in 68% (13/19 tumor-normal pairs) of the tumors. Expression levels of rRNA transcripts 18 S, 28 S, 5.8 S and 45 S external transcribed spacer (45 S ETS) greatly varied in the breast cancer cell lines regardless of their methylation status. Analyses of rRNA transcript expression levels in the breast tumor and normal matched tissues showed no significant difference when normalized with TBP. On the other hand, using the geometric mean of the rRNA expression values (GM-rRNA) as reference enabled us to identify significant changes in the relative expression of rRNAs in the tissue samples. We propose GM-rRNA normalization as a novel strategy to analyze expression differences between rRNA transcripts. Accordingly, the 18S rRNA/GM-rRNA ratio was significantly higher whereas the 5.8S rRNA/GM-rRNA ratio was significantly lower in breast tumor samples than this ratio in the matched normal samples. Moreover, the 18S rRNA/GM-rRNA ratio was negatively correlated with the 45 S rDNA promoter methylation level in the normal breast tissue samples, yet not in the breast tumors. Significant correlations observed between the expression levels of rRNA transcripts in the normal samples were lost in the tumor samples. We showed that the expression of rRNA transcripts may not be based solely on promoter methylation. Carcinogenesis may cause dysregulation of the correlation between spliced rRNA expression levels, possibly due to changes in rRNA processing, which requires further investigation.

Analysis of microRNA expression and function.

PubMed

Van Wynsberghe, Priscilla M; Chan, Shih-Peng; Slack, Frank J; Pasquinelli, Amy E

2011-01-01

Originally discovered in C. elegans, microRNAs (miRNAs) are small RNAs that regulate fundamental cellular processes in diverse organisms. MiRNAs are encoded within the genome and are initially transcribed as primary transcripts that can be several kilobases in length. Primary transcripts are successively cleaved by two RNase III enzymes, Drosha in the nucleus and Dicer in the cytoplasm, to produce ∼70 nucleotide (nt) long precursor miRNAs and 22 nt long mature miRNAs, respectively. Mature miRNAs regulate gene expression post-transcriptionally by imperfectly binding target mRNAs in association with the multiprotein RNA induced silencing complex (RISC). The conserved sequence, expression pattern, and function of some miRNAs across distinct species as well as the importance of specific miRNAs in many biological pathways have led to an explosion in the study of miRNA biogenesis, miRNA target identification, and miRNA target regulation. Many advances in our understanding of miRNA biology have come from studies in the powerful model organism C. elegans. This chapter reviews the current methods used in C. elegans to study miRNA biogenesis, small RNA populations, miRNA-protein complexes, and miRNA target regulation. Copyright © 2011 Elsevier Inc. All rights reserved.

Modeling RNA polymerase interaction in mitochondria of chordates

PubMed Central

2012-01-01

Background In previous work, we introduced a concept, a mathematical model and its computer realization that describe the interaction between bacterial and phage type RNA polymerases, protein factors, DNA and RNA secondary structures during transcription, including transcription initiation and termination. The model accurately reproduces changes of gene transcription level observed in polymerase sigma-subunit knockout and heat shock experiments in plant plastids. The corresponding computer program and a user guide are available at http://lab6.iitp.ru/en/rivals. Here we apply the model to the analysis of transcription and (partially) translation processes in the mitochondria of frog, rat and human. Notably, mitochondria possess only phage-type polymerases. We consider the entire mitochondrial genome so that our model allows RNA polymerases to complete more than one circle on the DNA strand. Results Our model of RNA polymerase interaction during transcription initiation and elongation accurately reproduces experimental data obtained for plastids. Moreover, it also reproduces evidence on bulk RNA concentrations and RNA half-lives in the mitochondria of frog, human with or without the MELAS mutation, and rat with normal (euthyroid) or hyposecretion of thyroid hormone (hypothyroid). The transcription characteristics predicted by the model include: (i) the fraction of polymerases terminating at a protein-dependent terminator in both directions (the terminator polarization), (ii) the binding intensities of the regulatory protein factor (mTERF) with the termination site and, (iii) the transcription initiation intensities (initiation frequencies) of all promoters in all five conditions (frog, healthy human, human with MELAS syndrome, healthy rat, and hypothyroid rat with aberrant mtDNA methylation). Using the model, absolute levels of all gene transcription can be inferred from an arbitrary array of the three transcription characteristics, whereas, for selected genes only relative RNA concentrations have been experimentally determined. Conversely, these characteristics and absolute transcription levels can be obtained using relative RNA concentrations and RNA half-lives known from various experimental studies. In this case, the “inverse problem” is solved with multi-objective optimization. Conclusions In this study, we demonstrate that our model accurately reproduces all relevant experimental data available for plant plastids, as well as the mitochondria of chordates. Using experimental data, the model is applied to estimate binding intensities of phage-type RNA polymerases to their promoters as well as predicting terminator characteristics, including polarization. In addition, one can predict characteristics of phage-type RNA polymerases and the transcription process that are difficult to measure directly, e.g., the association between the promoter’s nucleotide composition and the intensity of polymerase binding. To illustrate the application of our model in functional predictions, we propose a possible mechanism for MELAS syndrome development in human involving a decrease of Phe-tRNA, Val-tRNA and rRNA concentrations in the cell. In addition, we describe how changes in methylation patterns of the mTERF binding site and three promoters in hypothyroid rat correlate with changes in intensities of the mTERF binding and transcription initiations. Finally, we introduce an auxiliary model to describe the interaction between polysomal mRNA and ribonucleases. PMID:22873568

The Werner Syndrome Protein Is Involved in RNA Polymerase II Transcription

PubMed Central

Balajee, Adayabalam S.; Machwe, Amrita; May, Alfred; Gray, Matthew D.; Oshima, Junko; Martin, George M.; Nehlin, Jan O.; Brosh, Robert; Orren, David K.; Bohr, Vilhelm A.

1999-01-01

Werner syndrome (WS) is a human progeroid syndrome characterized by the early onset of a large number of clinical features associated with the normal aging process. The complex molecular and cellular phenotypes of WS involve characteristic features of genomic instability and accelerated replicative senescence. The gene involved (WRN) was recently cloned, and its gene product (WRNp) was biochemically characterized as a helicase. Helicases play important roles in a variety of DNA transactions, including DNA replication, transcription, repair, and recombination. We have assessed the role of the WRN gene in transcription by analyzing the efficiency of basal transcription in WS lymphoblastoid cell lines that carry homozygous WRN mutations. Transcription was measured in permeabilized cells by [3H]UTP incorporation and in vitro by using a plasmid template containing the RNA polymerase II (RNA pol II)–dependent adenovirus major late promoter. With both of these approaches, we find that the transcription efficiency in different WS cell lines is reduced to 40–60% of the transcription in cells from normal individuals. This defect can be complemented by the addition of normal cell extracts to the chromatin of WS cells. Addition of purified wild-type WRNp but not mutated WRNp to the in vitro transcription assay markedly stimulates RNA pol II–dependent transcription carried out by nuclear extracts. A nonhelicase domain (a direct repeat of 27 amino acids) also appears to have a role in transcription enhancement, as revealed by a yeast hybrid–protein reporter assay. This is further supported by the lack of stimulation of transcription when mutant WRNp lacking this domain was added to the in vitro assay. We have thus used several approaches to show a role for WRNp in RNA pol II transcription, possibly as a transcriptional activator. A deficit in either global or regional transcription in WS cells may be a primary molecular defect responsible for the WS clinical phenotype. PMID:10436020

Post-transcriptional Regulation of Tyrosine Hydroxylase Expression in Adrenal Medulla and Brain

PubMed Central

Tank, A. William; Xu, Lu; Chen, Xiqun; Radcliffe, Pheona; Sterling, Carol R.

2009-01-01

It is well-established that long-term stress leads to induction of tyrosine hydroxylase (TH) mRNA and TH protein in adrenal medulla and brain. This induction is usually associated with stimulation of TH gene transcription rate. However, a number of studies have reported major discrepancies between the stress-induced changes in TH gene transcription, TH mRNA and TH protein. These discrepancies suggest that post-transcriptional mechanisms also play an important role in regulating TH expression in response to stress and other stimuli. In this report we summarize some of our findings and literature reports that demonstrate these discrepancies in adrenal medulla, locus coeruleus and midbrain dopamine neurons. We then describe our recent work investigating the molecular mechanisms that mediate this post-transcriptional regulation in adrenal medulla and midbrain. Our results suggest that trans-acting factors binding to the polypyrimidine-rich region of the 3′UTR of TH mRNA play a role in these post-transcriptional mechanisms. A hypothetical cellular model describing this post-transcriptional regulation is proposed. PMID:19120116

The nuclear receptor ERβ engages AGO2 in regulation of gene transcription, RNA splicing and RISC loading.

PubMed

Tarallo, Roberta; Giurato, Giorgio; Bruno, Giuseppina; Ravo, Maria; Rizzo, Francesca; Salvati, Annamaria; Ricciardi, Luca; Marchese, Giovanna; Cordella, Angela; Rocco, Teresa; Gigantino, Valerio; Pierri, Biancamaria; Cimmino, Giovanni; Milanesi, Luciano; Ambrosino, Concetta; Nyman, Tuula A; Nassa, Giovanni; Weisz, Alessandro

2017-10-06

The RNA-binding protein Argonaute 2 (AGO2) is a key effector of RNA-silencing pathways It exerts a pivotal role in microRNA maturation and activity and can modulate chromatin remodeling, transcriptional gene regulation and RNA splicing. Estrogen receptor beta (ERβ) is endowed with oncosuppressive activities, antagonizing hormone-induced carcinogenesis and inhibiting growth and oncogenic functions in luminal-like breast cancers (BCs), where its expression correlates with a better prognosis of the disease. Applying interaction proteomics coupled to mass spectrometry to characterize nuclear factors cooperating with ERβ in gene regulation, we identify AGO2 as a novel partner of ERβ in human BC cells. ERβ-AGO2 association was confirmed in vitro and in vivo in both the nucleus and cytoplasm and is shown to be RNA-mediated. ChIP-Seq demonstrates AGO2 association with a large number of ERβ binding sites, and total and nascent RNA-Seq in ERβ + vs ERβ - cells, and before and after AGO2 knock-down in ERβ + cells, reveals a widespread involvement of this factor in ERβ-mediated regulation of gene transcription rate and RNA splicing. Moreover, isolation and sequencing by RIP-Seq of ERβ-associated long and small RNAs in the cytoplasm suggests involvement of the nuclear receptor in RISC loading, indicating that it may also be able to directly control mRNA translation efficiency and stability. These results demonstrate that AGO2 can act as a pleiotropic functional partner of ERβ, indicating that both factors are endowed with multiple roles in the control of key cellular functions.

Differential regulation of glutathione peroxidase by selenomethionine and hyperoxia in endothelial cells.

PubMed Central

Jornot, L; Junod, A F

1995-01-01

We have studied the effect of selenomethionine (SeMet) and hyperoxia on the expression of glutathione peroxidase (GP) in human umbilical vein endothelial cells. Incubation of HUVEC with 1 x 10(-6) M SeMet for 24 h and 48 h caused a 65% and 86% increase in GP activity respectively. The same treatment did not result in significant changes in GP gene transcription and mRNA levels. Pactamycin, a specific inhibitor of the initiation step of translation, prevented the rise in GP activity induced by SeMet and caused an increase in GP mRNA in both cells grown in normal and SeMet-supplemented medium. Interestingly, SeMet supplementation stimulated the recruitment of GP mRNA from an untranslatable pool on to polyribosomes, so that the concentration of GP mRNA in polyribosomal translatable pools was 50% higher in cells grown in SeMet-supplemented medium than in cells grown in normal medium. On the other hand, cells exposed to 95% O2 for 3 days in normal medium showed a 60%, 394% and 81% increase in GP gene transcription rate, mRNA levels and activity respectively. Hyperoxia also stabilized GP mRNA. Hyperoxic cells grown in SeMet-supplemented medium did not show any change in GP gene transcription and mRNA levels, but expressed an 81% and 100% increase in GP activity and amount of GP mRNA associated with polyribosomes respectively, when compared with hyperoxic cells maintained in normal medium. Thus, GP appeared to be regulated post-transcriptionally, most probably co-translationally, in response to selenium availability, and transcriptionally and post-transcriptionally in response to oxygen. Images Figure 1 Figure 2 Figure 4 Figure 7 Figure 8 PMID:7887914

A hyperactive transcriptional state marks genome reactivation at the mitosis–G1 transition

PubMed Central

Hsiung, Chris C.-S.; Bartman, Caroline R.; Huang, Peng; Ginart, Paul; Stonestrom, Aaron J.; Keller, Cheryl A.; Face, Carolyne; Jahn, Kristen S.; Evans, Perry; Sankaranarayanan, Laavanya; Giardine, Belinda; Hardison, Ross C.; Raj, Arjun; Blobel, Gerd A.

2016-01-01

During mitosis, RNA polymerase II (Pol II) and many transcription factors dissociate from chromatin, and transcription ceases globally. Transcription is known to restart in bulk by telophase, but whether de novo transcription at the mitosis–G1 transition is in any way distinct from later in interphase remains unknown. We tracked Pol II occupancy genome-wide in mammalian cells progressing from mitosis through late G1. Unexpectedly, during the earliest rounds of transcription at the mitosis–G1 transition, ∼50% of active genes and distal enhancers exhibit a spike in transcription, exceeding levels observed later in G1 phase. Enhancer–promoter chromatin contacts are depleted during mitosis and restored rapidly upon G1 entry but do not spike. Of the chromatin-associated features examined, histone H3 Lys27 acetylation levels at individual loci in mitosis best predict the mitosis–G1 transcriptional spike. Single-molecule RNA imaging supports that the mitosis–G1 transcriptional spike can constitute the maximum transcriptional activity per DNA copy throughout the cell division cycle. The transcriptional spike occurs heterogeneously and propagates to cell-to-cell differences in mature mRNA expression. Our results raise the possibility that passage through the mitosis–G1 transition might predispose cells to diverge in gene expression states. PMID:27340175

Natural antisense transcripts associated with salinity response in alfalfa

USDA-ARS?s Scientific Manuscript database

Natural antisense transcripts (NATs) are long non-coding RNAs (lncRNAs) complimentary to the messenger (sense) RNA (Wang et al. 2014). Many of them are involved in regulation of their own sense transcripts thus playing pivotal biological roles in all processes of organismal development and responses...

Brief Report: Effect of CMV and HIV Transcription on CD57 and PD-1 T-Cell Expression During Suppressive ART

PubMed Central

Massanella, Marta; Smith, Davey M.; Spina, Celsa A.; Schrier, Rachel; Daar, Eric S.; Dube, Michael P.; Morris, Sheldon R.; Gianella, Sara

2016-01-01

Abstract: HIV-infected men who have sex with men are nearly universally coinfected with cytomegalovirus (CMV). In this study of 45 HIV-infected men who have sex with men virologically suppressed on ART, we found that presence of seminal CMV DNA shedding and higher levels of systemic cellular HIV RNA transcription were both independently associated with increased PD-1 expression on circulating CD4+ T cells, but not with higher levels of senescent (CD57+) T cells. In addition, greater HIV RNA transcription was associated with lower CD57 expression on CD8 T cells. Although causality cannot be inferred from this retrospective study, these results suggest that asymptomatic CMV replication and residual cellular HIV transcription may contribute to persistent immune dysregulation during suppressive ART. PMID:26818740

Efficient trans-cleavage by the Schistosoma mansoni SMα1 hammerhead ribozyme in the extreme thermophile Thermus thermophilus

PubMed Central

Vazquez-Tello, Alejandro; Castán, Pablo; Moreno, Renata; Smith, James M.; Berenguer, José; Cedergren, Robert

2002-01-01

The catalytic hammerhead structure has been found in association with repetitive DNA from several animals, including salamanders, crickets and schistosomes, and functions to process in cis the long multimer transcripts into monomer RNA in vivo. The cellular role of these repetitive elements and their transcripts is unknown. Moreover, none of these natural hammerheads have been shown to trans-cleave a host mRNA in vivo. We analyzed the cis- and trans-cleavage properties of the hammerhead ribozyme associated with the SMα DNA family from the human parasite Schistosoma mansoni. The efficiency of trans-cleavage of a target RNA in vitro was affected mainly by both the temperature-dependent chemical step and the ribozyme–product dissociation step. The optimal temperature for trans-cleavage was 70°C. This result was confirmed when both the SMα1 ribozyme and the target RNA were expressed in the extreme thermophile Thermus thermophilus. Moreover, SMα1 RNA showed a remarkable thermostability, equal or superior to that of the most stable RNAs in this species, suggesting that SMα1 RNA has been selected for stability. Computer analysis predicts that the monomer and multimer transcripts fold into highly compact secondary structures, which may explain their exceptional stability in vivo. PMID:11917021

Insights into RNA processing pathways and associated-RNA degrading enzymes in Archaea.

PubMed

Clouet-d'Orval, Béatrice; Batista, Manon; Bouvier, Marie; Quentin, Yves; Fichant, Gwennaele; Marchfelder, Anita; Maier, Lisa-Katharina

2018-04-19

RNA processing pathways are at the center of regulation of gene expression. All RNA transcripts undergo multiple maturation steps in addition to covalent chemical modifications to become functional in the cell. This includes destroying unnecessary or defective cellular RNAs. In Archaea, information on mechanisms by which RNA species reach their mature forms and associated RNA-modifying enzymes is still fragmentary. To date, most archaeal actors and pathways have been proposed in light of information gathered from Bacteria and Eukarya. In this context, this review provides a state of the art overview of archaeal endoribonucleases and exoribonucleases that cleave and trim RNA species and also of the key small archaeal proteins that bind RNAs. Furthermore, synthetic up-to-date views of processing and biogenesis pathways of archaeal transfer and ribosomal RNAs as well as of maturation of stable small non-coding RNAs such as CRISPR RNAs, small C/D and H/ACA box guide RNAs, and other emerging classes of small RNAs are described. Finally prospective post-transcriptional mechanisms to control archaeal messenger RNA quality and quantity are discussed.

Transgenerationally inherited piRNAs trigger piRNA biogenesis by changing the chromatin of piRNA clusters and inducing precursor processing

PubMed Central

Le Thomas, Adrien; Stuwe, Evelyn; Li, Sisi; Marinov, Georgi; Rozhkov, Nikolay; Chen, Yung-Chia Ariel; Luo, Yicheng; Sachidanandam, Ravi; Toth, Katalin Fejes; Patel, Dinshaw; Aravin, Alexei A.

2014-01-01

Small noncoding RNAs that associate with Piwi proteins, called piRNAs, serve as guides for repression of diverse transposable elements in germ cells of metazoa. In Drosophila, the genomic regions that give rise to piRNAs, the so-called piRNA clusters, are transcribed to generate long precursor molecules that are processed into mature piRNAs. How genomic regions that give rise to piRNA precursor transcripts are differentiated from the rest of the genome and how these transcripts are specifically channeled into the piRNA biogenesis pathway are not known. We found that transgenerationally inherited piRNAs provide the critical trigger for piRNA production from homologous genomic regions in the next generation by two different mechanisms. First, inherited piRNAs enhance processing of homologous transcripts into mature piRNAs by initiating the ping-pong cycle in the cytoplasm. Second, inherited piRNAs induce installment of the histone 3 Lys9 trimethylation (H3K9me3) mark on genomic piRNA cluster sequences. The heterochromatin protein 1 (HP1) homolog Rhino binds to the H3K9me3 mark through its chromodomain and is enriched over piRNA clusters. Rhino recruits the piRNA biogenesis factor Cutoff to piRNA clusters and is required for efficient transcription of piRNA precursors. We propose that transgenerationally inherited piRNAs act as an epigenetic memory for identification of substrates for piRNA biogenesis on two levels: by inducing a permissive chromatin environment for piRNA precursor synthesis and by enhancing processing of these precursors. PMID:25085419

Hepatic Long Intergenic Noncoding RNAs: High Promoter Conservation and Dynamic, Sex-Dependent Transcriptional Regulation by Growth Hormone

PubMed Central

Melia, Tisha; Hao, Pengying; Yilmaz, Feyza

2015-01-01

Long intergenic noncoding RNAs (lincRNAs) are increasingly recognized as key chromatin regulators, yet few studies have characterized lincRNAs in a single tissue under diverse conditions. Here, we analyzed 45 mouse liver RNA sequencing (RNA-Seq) data sets collected under diverse conditions to systematically characterize 4,961 liver lincRNAs, 59% of them novel, with regard to gene structures, species conservation, chromatin accessibility, transcription factor binding, and epigenetic states. To investigate the potential for functionality, we focused on the responses of the liver lincRNAs to growth hormone stimulation, which imparts clinically relevant sex differences to hepatic metabolism and liver disease susceptibility. Sex-biased expression characterized 247 liver lincRNAs, with many being nuclear RNA enriched and regulated by growth hormone. The sex-biased lincRNA genes are enriched for nearby and correspondingly sex-biased accessible chromatin regions, as well as sex-biased binding sites for growth hormone-regulated transcriptional activators (STAT5, hepatocyte nuclear factor 6 [HNF6], FOXA1, and FOXA2) and transcriptional repressors (CUX2 and BCL6). Repression of female-specific lincRNAs in male liver, but not that of male-specific lincRNAs in female liver, was associated with enrichment of H3K27me3-associated inactive states and poised (bivalent) enhancer states. Strikingly, we found that liver-specific lincRNA gene promoters are more highly species conserved and have a significantly higher frequency of proximal binding by liver transcription factors than liver-specific protein-coding gene promoters. Orthologs for many liver lincRNAs were identified in one or more supraprimates, including two rat lincRNAs showing the same growth hormone-regulated, sex-biased expression as their mouse counterparts. This integrative analysis of liver lincRNA chromatin states, transcription factor occupancy, and growth hormone regulation provides novel insights into the expression of sex-specific lincRNAs and their potential for regulation of sex differences in liver physiology and disease. PMID:26459762

Microprocessor Recruitment to Elongating RNA Polymerase II Is Required for Differential Expression of MicroRNAs.

PubMed

Church, Victoria A; Pressman, Sigal; Isaji, Mamiko; Truscott, Mary; Cizmecioglu, Nihal Terzi; Buratowski, Stephen; Frolov, Maxim V; Carthew, Richard W

2017-09-26

The cellular abundance of mature microRNAs (miRNAs) is dictated by the efficiency of nuclear processing of primary miRNA transcripts (pri-miRNAs) into pre-miRNA intermediates. The Microprocessor complex of Drosha and DGCR8 carries this out, but it has been unclear what controls Microprocessor's differential processing of various pri-miRNAs. Here, we show that Drosophila DGCR8 (Pasha) directly associates with the C-terminal domain of the RNA polymerase II elongation complex when it is phosphorylated by the Cdk9 kinase (pTEFb). When association is blocked by loss of Cdk9 activity, a global change in pri-miRNA processing is detected. Processing of pri-miRNAs with a UGU sequence motif in their apical junction domain increases, while processing of pri-miRNAs lacking this motif decreases. Therefore, phosphorylation of RNA polymerase II recruits Microprocessor for co-transcriptional processing of non-UGU pri-miRNAs that would otherwise be poorly processed. In contrast, UGU-positive pri-miRNAs are robustly processed by Microprocessor independent of RNA polymerase association. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Molecular genetic mechanisms of allelic specific regulation of murine Comt expression

PubMed Central

Segall, Samantha K.; Shabalina, Svetlana A.; Meloto, Carolina B.; Wen, Xia; Cunningham, Danielle; Tarantino, Lisa M.; Wiltshire, Tim; Gauthier, Josée; Tohyama, Sarasa; Martin, Loren J.; Mogil, Jeffrey S.; Diatchenko, Luda

2015-01-01

Abstract A functional allele of the mouse catechol-O-methyltransferase (Comt) gene is defined by the insertion of a B2 short interspersed repeat element in its 3′-untranslated region (UTR). This allele has been associated with a number of phenotypes, such as pain and anxiety. In comparison with mice carrying the ancestral allele (Comt+), ComtB2i mice show higher Comt mRNA and enzymatic activity levels. Here, we investigated the molecular genetic mechanisms underlying this allelic specific regulation of Comt expression. Insertion of the B2 element introduces an early polyadenylation signal generating a shorter Comt transcript, in addition to the longer ancestral mRNA. Comparative analysis and in silico prediction of Comt mRNA potential targets within the transcript 3′ to the B2 element was performed and allowed choosing microRNA (miRNA) candidates for experimental screening: mmu-miR-3470a, mmu-miR-3470b, and mmu-miR-667. Cell transfection with each miRNA downregulated the expression of the ancestral transcript and COMT enzymatic activity. Our in vivo experiments showed that mmu-miR-667-3p is strongly correlated with decreasing amounts of Comt mRNA in the brain, and lentiviral injections of mmu-miR-3470a, mmu-miR-3470b, and mmu-miR-667 increase hypersensitivity in the mouse formalin model, consistent with reduced COMT activity. In summary, our data demonstrate that the Comt+ transcript contains regulatory miRNA signals in its 3′-untranslated region leading to mRNA degradation; these signals, however, are absent in the shorter transcript, resulting in higher mRNA expression and activity levels. PMID:26067582

Contributions of in vitro transcription to the understanding of human RNA polymerase III transcription

PubMed Central

Dumay-Odelot, Hélène; Durrieu-Gaillard, Stéphanie; El Ayoubi, Leyla; Parrot, Camila; Teichmann, Martin

2014-01-01

Human RNA polymerase III transcribes small untranslated RNAs that contribute to the regulation of essential cellular processes, including transcription, RNA processing and translation. Analysis of this transcription system by in vitro transcription techniques has largely contributed to the discovery of its transcription factors and to the understanding of the regulation of human RNA polymerase III transcription. Here we review some of the key steps that led to the identification of transcription factors and to the definition of minimal promoter sequences for human RNA polymerase III transcription. PMID:25764111

The Nuclear Pore-Associated TREX-2 Complex Employs Mediator to Regulate Gene Expression

PubMed Central

Schneider, Maren; Hellerschmied, Doris; Schubert, Tobias; Amlacher, Stefan; Vinayachandran, Vinesh; Reja, Rohit; Pugh, B. Franklin; Clausen, Tim; Köhler, Alwin

2015-01-01

Summary Nuclear pore complexes (NPCs) influence gene expression besides their established function in nuclear transport. The TREX-2 complex localizes to the NPC basket and affects gene-NPC interactions, transcription, and mRNA export. How TREX-2 regulates the gene expression machinery is unknown. Here, we show that TREX-2 interacts with the Mediator complex, an essential regulator of RNA Polymerase (Pol) II. Structural and biochemical studies identify a conserved region on TREX-2, which directly binds the Mediator Med31/Med7N submodule. TREX-2 regulates assembly of Mediator with the Cdk8 kinase and is required for recruitment and site-specific phosphorylation of Pol II. Transcriptome and phenotypic profiling confirm that TREX-2 and Med31 are functionally interdependent at specific genes. TREX-2 additionally uses its Mediator-interacting surface to regulate mRNA export suggesting a mechanism for coupling transcription initiation and early steps of mRNA processing. Our data provide mechanistic insight into how an NPC-associated adaptor complex accesses the core transcription machinery. PMID:26317468

Identification and Characterization of a Cis-Encoded Antisense RNA Associated with the Replication Process of Salmonella enterica Serovar Typhi

PubMed Central

Dadzie, Isaac; Xu, Shungao; Ni, Bin; Zhang, Xiaolei; Zhang, Haifang; Sheng, Xiumei; Xu, Huaxi; Huang, Xinxiang

2013-01-01

Antisense RNAs that originate from the complementary strand of protein coding genes are involved in the regulation of gene expression in all domains of life. In bacteria, some of these antisense RNAs are transcriptional noise whiles others play a vital role to adapt the cell to changing environmental conditions. By deep sequencing analysis of transcriptome of Salmonella enterica serovar Typhi, a partial RNA sequence encoded in-cis to the dnaA gene was revealed. Northern blot and RACE analysis confirmed the transcription of this antisense RNA which was expressed mostly in the stationary phase of the bacterial growth and also under iron limitation and osmotic stress. Pulse expression analysis showed that overexpression of the antisense RNA resulted in a significant increase in the mRNA levels of dnaA, which will ultimately enhance their translation. Our findings have revealed that antisense RNA of dnaA is indeed transcribed not merely as a by-product of the cell's transcription machinery but plays a vital role as far as stability of dnaA mRNA is concerned. PMID:23637809

Circular RNA Profiling and Bioinformatic Modeling Identify Its Regulatory Role in Hepatic Steatosis.

PubMed

Guo, Xing-Ya; He, Chong-Xin; Wang, Yu-Qin; Sun, Chao; Li, Guang-Ming; Su, Qing; Pan, Qin; Fan, Jian-Gao

2017-01-01

Circular RNAs (circRNAs) exhibit a wide range of physiological and pathological activities. To uncover their role in hepatic steatosis, we investigated the expression profile of circRNAs in HepG2-based hepatic steatosis induced by high-fat stimulation. Differentially expressed circRNAs were subjected to validation using QPCR and functional analyses using principal component analysis, hierarchical clustering, target prediction, gene ontology (GO), and pathway annotation, respectively. Bioinformatic integration established the circRNA-miRNA-mRNA regulatory network so as to identify the mechanisms underlying circRNAs' metabolic effect. Here we reported that hepatic steatosis was associated with a total of 357 circRNAs. Enrichment of transcription-related GOs, especially GO: 0006355, GO: 004589, GO: 0045944, GO: 0045892, and GO: 0000122, demonstrated their specific actions in transcriptional regulation. Lipin 1 (LPIN1) was recognized to mediate the transcriptional regulatory effect of circRNAs on metabolic pathways. circRNA-miRNA-mRNA network further identified the signaling cascade of circRNA_021412/miR-1972/LPIN1, which was characterized by decreased level of circRNA_021412 and miR-1972-based inhibition of LPIN1. LPIN1-induced downregulation of long chain acyl-CoA synthetases (ACSLs) expression finally resulted in the hepatosteatosis. These findings identify circRNAs to be important regulators of hepatic steatosis. Transcription-dependent modulation of metabolic pathways may underlie their effects, partially by the circRNA_021412/miR-1972/LPIN1 signaling.

Post-transcriptional regulatory network of epithelial-to-mesenchymal and mesenchymal-to-epithelial transitions

PubMed Central

2014-01-01

Epithelial-to-mesenchymal transition (EMT) and its reverse process, mesenchymal-to-epithelial transition (MET), play important roles in embryogenesis, stem cell biology, and cancer progression. EMT can be regulated by many signaling pathways and regulatory transcriptional networks. Furthermore, post-transcriptional regulatory networks regulate EMT; these networks include the long non-coding RNA (lncRNA) and microRNA (miRNA) families. Specifically, the miR-200 family, miR-101, miR-506, and several lncRNAs have been found to regulate EMT. Recent studies have illustrated that several lncRNAs are overexpressed in various cancers and that they can promote tumor metastasis by inducing EMT. MiRNA controls EMT by regulating EMT transcription factors or other EMT regulators, suggesting that lncRNAs and miRNA are novel therapeutic targets for the treatment of cancer. Further efforts have shown that non-coding-mediated EMT regulation is closely associated with epigenetic regulation through promoter methylation (e.g., miR-200 or miR-506) and protein regulation (e.g., SET8 via miR-502). The formation of gene fusions has also been found to promote EMT in prostate cancer. In this review, we discuss the post-transcriptional regulatory network that is involved in EMT and MET and how targeting EMT and MET may provide effective therapeutics for human disease. PMID:24598126

The legume miR1514a modulates a NAC transcription factor transcript to trigger phasiRNA formation in response to drought

PubMed Central

Sosa-Valencia, Guadalupe; Palomar, Miguel; Covarrubias, Alejandra A.

2017-01-01

Abstract Recent studies have identified microRNAs as post-transcriptional regulators involved in stress responses. miR1514a is a legume microRNA that is induced in response to drought stress in Phaseolus vulgaris (common bean) and shows differential accumulation levels in roots during water deficit in two cultivars with different drought tolerance phenotypes. A recent degradome analysis revealed that miR1514a targets the transcripts of two NAC transcription factors (TFs), Phvul.010g121000 and Phvul.010g120700. Furthermore, expression studies and small RNA-seq data indicate that only Phvul.010g120700 generates phasiRNAs, which also accumulate under water deficit conditions. To confirm these results, we over-expressed miR1514a in transgenic hairy roots, and observed a reduced accumulation of Phvul.010g120700 and an increase in NAC-derived phasiRNAs; inhibition of miR1514a activity resulted in the opposite effect. Moreover, we determined that a NAC-derived phasiRNA associates with ARGONAUTE 1 (AGO1), suggesting that it is functional. In addition, a transcriptome analysis of transgenic hairy roots with reduced miR1514a levels revealed several differentially expressed transcripts, mainly involved in metabolism and stress responses, suggesting they are regulated by the NAC TF and/or by phasiRNAs. This work therefore demonstrates the participation of miR1514 in the regulation of a NAC transcription factor transcript through phasiRNA production during the plant response to water deficit. PMID:28338719

Unique transcriptomic signature of omental adipose tissue in Ossabaw swine: a model of childhood obesity.

PubMed

Toedebusch, Ryan G; Roberts, Michael D; Wells, Kevin D; Company, Joseph M; Kanosky, Kayla M; Padilla, Jaume; Jenkins, Nathan T; Perfield, James W; Ibdah, Jamal A; Booth, Frank W; Rector, R Scott

2014-05-15

To better understand the impact of childhood obesity on intra-abdominal adipose tissue phenotype, a complete transcriptomic analysis using deep RNA-sequencing (RNA-seq) was performed on omental adipose tissue (OMAT) obtained from lean and Western diet-induced obese juvenile Ossabaw swine. Obese animals had 88% greater body mass, 49% greater body fat content, and a 60% increase in OMAT adipocyte area (all P < 0.05) compared with lean pigs. RNA-seq revealed a 37% increase in the total transcript number in the OMAT of obese pigs. Ingenuity Pathway Analysis showed transcripts in obese OMAT were primarily enriched in the following categories: 1) development, 2) cellular function and maintenance, and 3) connective tissue development and function, while transcripts associated with RNA posttranslational modification, lipid metabolism, and small molecule biochemistry were reduced. DAVID and Gene Ontology analyses showed that many of the classically recognized gene pathways associated with adipose tissue dysfunction in obese adults including hypoxia, inflammation, angiogenesis were not altered in OMAT in our model. The current study indicates that obesity in juvenile Ossabaw swine is characterized by increases in overall OMAT transcript number and provides novel data describing early transcriptomic alterations that occur in response to excess caloric intake in visceral adipose tissue in a pig model of childhood obesity.

Unique transcriptomic signature of omental adipose tissue in Ossabaw swine: a model of childhood obesity

PubMed Central

Toedebusch, Ryan G.; Roberts, Michael D.; Wells, Kevin D.; Company, Joseph M.; Kanosky, Kayla M.; Padilla, Jaume; Jenkins, Nathan T.; Perfield, James W.; Ibdah, Jamal A.; Booth, Frank W.

2014-01-01

To better understand the impact of childhood obesity on intra-abdominal adipose tissue phenotype, a complete transcriptomic analysis using deep RNA-sequencing (RNA-seq) was performed on omental adipose tissue (OMAT) obtained from lean and Western diet-induced obese juvenile Ossabaw swine. Obese animals had 88% greater body mass, 49% greater body fat content, and a 60% increase in OMAT adipocyte area (all P < 0.05) compared with lean pigs. RNA-seq revealed a 37% increase in the total transcript number in the OMAT of obese pigs. Ingenuity Pathway Analysis showed transcripts in obese OMAT were primarily enriched in the following categories: 1) development, 2) cellular function and maintenance, and 3) connective tissue development and function, while transcripts associated with RNA posttranslational modification, lipid metabolism, and small molecule biochemistry were reduced. DAVID and Gene Ontology analyses showed that many of the classically recognized gene pathways associated with adipose tissue dysfunction in obese adults including hypoxia, inflammation, angiogenesis were not altered in OMAT in our model. The current study indicates that obesity in juvenile Ossabaw swine is characterized by increases in overall OMAT transcript number and provides novel data describing early transcriptomic alterations that occur in response to excess caloric intake in visceral adipose tissue in a pig model of childhood obesity. PMID:24642759

A common class of transcripts with 5'-intron depletion, distinct early coding sequence features, and N1-methyladenosine modification.

PubMed

Cenik, Can; Chua, Hon Nian; Singh, Guramrit; Akef, Abdalla; Snyder, Michael P; Palazzo, Alexander F; Moore, Melissa J; Roth, Frederick P

2017-03-01

Introns are found in 5' untranslated regions (5'UTRs) for 35% of all human transcripts. These 5'UTR introns are not randomly distributed: Genes that encode secreted, membrane-bound and mitochondrial proteins are less likely to have them. Curiously, transcripts lacking 5'UTR introns tend to harbor specific RNA sequence elements in their early coding regions. To model and understand the connection between coding-region sequence and 5'UTR intron status, we developed a classifier that can predict 5'UTR intron status with >80% accuracy using only sequence features in the early coding region. Thus, the classifier identifies transcripts with 5 ' proximal- i ntron- m inus-like-coding regions ("5IM" transcripts). Unexpectedly, we found that the early coding sequence features defining 5IM transcripts are widespread, appearing in 21% of all human RefSeq transcripts. The 5IM class of transcripts is enriched for non-AUG start codons, more extensive secondary structure both preceding the start codon and near the 5' cap, greater dependence on eIF4E for translation, and association with ER-proximal ribosomes. 5IM transcripts are bound by the exon junction complex (EJC) at noncanonical 5' proximal positions. Finally, N 1 -methyladenosines are specifically enriched in the early coding regions of 5IM transcripts. Taken together, our analyses point to the existence of a distinct 5IM class comprising ∼20% of human transcripts. This class is defined by depletion of 5' proximal introns, presence of specific RNA sequence features associated with low translation efficiency, N 1 -methyladenosines in the early coding region, and enrichment for noncanonical binding by the EJC. © 2017 Cenik et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

Genome-Wide Spectra of Transcription Insertions and Deletions Reveal That Slippage Depends on RNA:DNA Hybrid Complementarity

PubMed Central

Traverse, Charles C.

2017-01-01

ABSTRACT Advances in sequencing technologies have enabled direct quantification of genome-wide errors that occur during RNA transcription. These errors occur at rates that are orders of magnitude higher than rates during DNA replication, but due to technical difficulties such measurements have been limited to single-base substitutions and have not yet quantified the scope of transcription insertions and deletions. Previous reporter gene assay findings suggested that transcription indels are produced exclusively by elongation complex slippage at homopolymeric runs, so we enumerated indels across the protein-coding transcriptomes of Escherichia coli and Buchnera aphidicola, which differ widely in their genomic base compositions and incidence of repeat regions. As anticipated from prior assays, transcription insertions prevailed in homopolymeric runs of A and T; however, transcription deletions arose in much more complex sequences and were rarely associated with homopolymeric runs. By reconstructing the relocated positions of the elongation complex as inferred from the sequences inserted or deleted during transcription, we show that continuation of transcription after slippage hinges on the degree of nucleotide complementarity within the RNA:DNA hybrid at the new DNA template location. PMID:28851848

Gene expression profiling of whole blood: Comparison of target preparation methods for accurate and reproducible microarray analysis

PubMed Central

Vartanian, Kristina; Slottke, Rachel; Johnstone, Timothy; Casale, Amanda; Planck, Stephen R; Choi, Dongseok; Smith, Justine R; Rosenbaum, James T; Harrington, Christina A

2009-01-01

Background Peripheral blood is an accessible and informative source of transcriptomal information for many human disease and pharmacogenomic studies. While there can be significant advantages to analyzing RNA isolated from whole blood, particularly in clinical studies, the preparation of samples for microarray analysis is complicated by the need to minimize artifacts associated with highly abundant globin RNA transcripts. The impact of globin RNA transcripts on expression profiling data can potentially be reduced by using RNA preparation and labeling methods that remove or block globin RNA during the microarray assay. We compared four different methods for preparing microarray hybridization targets from human whole blood collected in PAXGene tubes. Three of the methods utilized the Affymetrix one-cycle cDNA synthesis/in vitro transcription protocol but varied treatment of input RNA as follows: i. no treatment; ii. treatment with GLOBINclear; or iii. treatment with globin PNA oligos. In the fourth method cDNA targets were prepared with the Ovation amplification and labeling system. Results We find that microarray targets generated with labeling methods that reduce globin mRNA levels or minimize the impact of globin transcripts during hybridization detect more transcripts in the microarray assay compared with the standard Affymetrix method. Comparison of microarray results with quantitative PCR analysis of a panel of genes from the NF-kappa B pathway shows good correlation of transcript measurements produced with all four target preparation methods, although method-specific differences in overall correlation were observed. The impact of freezing blood collected in PAXGene tubes on data reproducibility was also examined. Expression profiles show little or no difference when RNA is extracted from either fresh or frozen blood samples. Conclusion RNA preparation and labeling methods designed to reduce the impact of globin mRNA transcripts can significantly improve the sensitivity of the DNA microarray expression profiling assay for whole blood samples. While blockage of globin transcripts during first strand cDNA synthesis with globin PNAs resulted in the best overall performance in this study, we conclude that selection of a protocol for expression profiling studies in blood should depend on several factors, including implementation requirements of the method and study design. RNA isolated from either freshly collected or frozen blood samples stored in PAXGene tubes can be used without altering gene expression profiles. PMID:19123946

Transcriptional analysis of phloem-associated cells of potato.

PubMed

Lin, Tian; Lashbrook, Coralie C; Cho, Sung Ki; Butler, Nathaniel M; Sharma, Pooja; Muppirala, Usha; Severin, Andrew J; Hannapel, David J

2015-09-03

Numerous signal molecules, including proteins and mRNAs, are transported through the architecture of plants via the vascular system. As the connection between leaves and other organs, the petiole and stem are especially important in their transport function, which is carried out by the phloem and xylem, especially by the sieve elements in the phloem system. The phloem is an important conduit for transporting photosynthate and signal molecules like metabolites, proteins, small RNAs, and full-length mRNAs. Phloem sap has been used as an unadulterated source to profile phloem proteins and RNAs, but unfortunately, pure phloem sap cannot be obtained in most plant species. Here we make use of laser capture microdissection (LCM) and RNA-seq for an in-depth transcriptional profile of phloem-associated cells of both petioles and stems of potato. To expedite our analysis, we have taken advantage of the potato genome that has recently been fully sequenced and annotated. Out of the 27 k transcripts assembled that we identified, approximately 15 k were present in phloem-associated cells of petiole and stem with greater than ten reads. Among these genes, roughly 10 k are affected by photoperiod. Several RNAs from this day length-regulated group are also abundant in phloem cells of petioles and encode for proteins involved in signaling or transcriptional control. Approximately 22 % of the transcripts in phloem cells contained at least one binding motif for Pumilio, Nova, or polypyrimidine tract-binding proteins in their downstream sequences. Highlighting the predominance of binding processes identified in the gene ontology analysis of active genes from phloem cells, 78 % of the 464 RNA-binding proteins present in the potato genome were detected in our phloem transcriptome. As a reasonable alternative when phloem sap collection is not possible, LCM can be used to isolate RNA from specific cell types, and along with RNA-seq, provides practical access to expression profiles of phloem tissue. The combination of these techniques provides a useful approach to the study of phloem and a comprehensive picture of the mechanisms associated with long-distance signaling. The data presented here provide valuable insights into potentially novel phloem-mobile mRNAs and phloem-associated RNA-binding proteins.

Profiling of m6A RNA modifications identified an age-associated regulation of AGO2 mRNA stability.

PubMed

Min, Kyung-Won; Zealy, Richard W; Davila, Sylvia; Fomin, Mikhail; Cummings, James C; Makowsky, Daniel; Mcdowell, Catherine H; Thigpen, Haley; Hafner, Markus; Kwon, Sang-Ho; Georgescu, Constantin; Wren, Jonathan D; Yoon, Je-Hyun

2018-06-01

Gene expression is dynamically regulated in a variety of mammalian physiologies. During mammalian aging, there are changes that occur in protein expression that are highly controlled by the regulatory steps in transcription, post-transcription, and post-translation. Although there are global profiles of human transcripts during the aging processes available, the mechanism(s) by which transcripts are differentially expressed between young and old cohorts remains unclear. Here, we report on N6-methyladenosine (m6A) RNA modification profiles of human peripheral blood mononuclear cells (PBMCs) from young and old cohorts. An m6A RNA profile identified a decrease in overall RNA methylation during the aging process as well as the predominant modification on proteincoding mRNAs. The m6A-modified transcripts tend to be more highly expressed than nonmodified ones. Among the many methylated mRNAs, those of DROSHA and AGO2 were heavily methylated in young PBMCs which coincided with a decreased steady-state level of AGO2 mRNA in the old PBMC cohort. Similarly, downregulation of AGO2 in proliferating human diploid fibroblasts (HDFs) also correlated with a decrease in AGO2 mRNA modifications and steady-state levels. In addition, the overexpression of RNA methyltransferases stabilized AGO2 mRNA but not DROSHA and DICER1 mRNA in HDFs. Moreover, the abundance of miRNAs also changed in the young and old PBMCs which are possibly due to a correlation with AGO2 expression as observed in AGO2-depleted HDFs. Taken together, we uncovered the role of mRNA methylation on the abundance of AGO2 mRNA resulting in the repression of miRNA expression during the process of human aging. © 2018 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

In silico methods for co-transcriptional RNA secondary structure prediction and for investigating alternative RNA structure expression.

PubMed

Meyer, Irmtraud M

2017-05-01

RNA transcripts are the primary products of active genes in any living organism, including many viruses. Their cellular destiny not only depends on primary sequence signals, but can also be determined by RNA structure. Recent experimental evidence shows that many transcripts can be assigned more than a single functional RNA structure throughout their cellular life and that structure formation happens co-transcriptionally, i.e. as the transcript is synthesised in the cell. Moreover, functional RNA structures are not limited to non-coding transcripts, but can also feature in coding transcripts. The picture that now emerges is that RNA structures constitute an additional layer of information that can be encoded in any RNA transcript (and on top of other layers of information such as protein-context) in order to exert a wide range of functional roles. Moreover, different encoded RNA structures can be expressed at different stages of a transcript's life in order to alter the transcript's behaviour depending on its actual cellular context. Similar to the concept of alternative splicing for protein-coding genes, where a single transcript can yield different proteins depending on cellular context, it is thus appropriate to propose the notion of alternative RNA structure expression for any given transcript. This review introduces several computational strategies that my group developed to detect different aspects of RNA structure expression in vivo. Two aspects are of particular interest to us: (1) RNA secondary structure features that emerge during co-transcriptional folding and (2) functional RNA structure features that are expressed at different times of a transcript's life and potentially mutually exclusive. Copyright © 2017. Published by Elsevier Inc.

Removing the needle from the haystack: Enrichment of Wolbachia endosymbiont transcripts from host nematode RNA by Cappable-seq™.

PubMed

Luck, Ashley N; Slatko, Barton E; Foster, Jeremy M

2017-01-01

Efficient transcriptomic sequencing of microbial mRNA derived from host-microbe associations is often compromised by the much lower relative abundance of microbial RNA in the mixed total RNA sample. One solution to this problem is to perform extensive sequencing until an acceptable level of transcriptome coverage is obtained. More cost-effective methods include use of prokaryotic and/or eukaryotic rRNA depletion strategies, sometimes in conjunction with depletion of polyadenylated eukaryotic mRNA. Here, we report use of Cappable-seq™ to specifically enrich, in a single step, Wolbachia endobacterial mRNA transcripts from total RNA prepared from the parasitic filarial nematode, Brugia malayi. The obligate Wolbachia endosymbiont is a proven drug target for many human filarial infections, yet the precise nature of its symbiosis with the nematode host is poorly understood. Insightful analysis of the expression levels of Wolbachia genes predicted to underpin the mutualistic association and of known drug target genes at different life cycle stages or in response to drug treatments is typically challenged by low transcriptomic coverage. Cappable-seq resulted in up to ~ 5-fold increase in the number of reads mapping to Wolbachia. On average, coverage of Wolbachia transcripts from B. malayi microfilariae was enriched ~40-fold by Cappable-seq. Additionally, this method has an additional benefit of selectively removing abundant prokaryotic ribosomal RNAs.The deeper microbial transcriptome sequencing afforded by Cappable-seq facilitates more detailed characterization of gene expression levels of pathogens and symbionts present in animal tissues.

The histone variant H2A.Z promotes efficient cotranscriptional splicing in S. cerevisiae

PubMed Central

Neves, Lauren T.; Douglass, Stephen; Spreafico, Roberto; Venkataramanan, Srivats; Kress, Tracy L.; Johnson, Tracy L.

2017-01-01

In eukaryotes, a dynamic ribonucleic protein machine known as the spliceosome catalyzes the removal of introns from premessenger RNA (pre-mRNA). Recent studies show the processes of RNA synthesis and RNA processing to be spatio–temporally coordinated, indicating that RNA splicing takes place in the context of chromatin. H2A.Z is a highly conserved histone variant of the canonical histone H2A. In Saccharomyces cerevisiae, H2A.Z is deposited into chromatin by the SWR-C complex, is found near the 5′ ends of protein-coding genes, and has been implicated in transcription regulation. Here we show that splicing of intron-containing genes in cells lacking H2A.Z is impaired, particularly under suboptimal splicing conditions. Cells lacking H2A.Z are especially dependent on a functional U2 snRNP (small nuclear RNA [snRNA] plus associated proteins), as H2A.Z shows extensive genetic interactions with U2 snRNP-associated proteins, and RNA sequencing (RNA-seq) reveals that introns with nonconsensus branch points are particularly sensitive to H2A.Z loss. Consistently, H2A.Z promotes efficient spliceosomal rearrangements involving the U2 snRNP, as H2A.Z loss results in persistent U2 snRNP association and decreased recruitment of downstream snRNPs to nascent RNA. H2A.Z impairs transcription elongation, suggesting that spliceosome rearrangements are tied to H2A.Z's role in elongation. Depletion of disassembly factor Prp43 suppresses H2A.Z-mediated splice defects, indicating that, in the absence of H2A.Z, stalled spliceosomes are disassembled, and unspliced RNAs are released. Together, these data demonstrate that H2A.Z is required for efficient pre-mRNA splicing and indicate a role for H2A.Z in coordinating the kinetics of transcription elongation and splicing. PMID:28446598

Natural genetic variation of the cardiac transcriptome in non-diseased donors and patients with dilated cardiomyopathy.

PubMed

Heinig, Matthias; Adriaens, Michiel E; Schafer, Sebastian; van Deutekom, Hanneke W M; Lodder, Elisabeth M; Ware, James S; Schneider, Valentin; Felkin, Leanne E; Creemers, Esther E; Meder, Benjamin; Katus, Hugo A; Rühle, Frank; Stoll, Monika; Cambien, François; Villard, Eric; Charron, Philippe; Varro, Andras; Bishopric, Nanette H; George, Alfred L; Dos Remedios, Cristobal; Moreno-Moral, Aida; Pesce, Francesco; Bauerfeind, Anja; Rüschendorf, Franz; Rintisch, Carola; Petretto, Enrico; Barton, Paul J; Cook, Stuart A; Pinto, Yigal M; Bezzina, Connie R; Hubner, Norbert

2017-09-14

Genetic variation is an important determinant of RNA transcription and splicing, which in turn contributes to variation in human traits, including cardiovascular diseases. Here we report the first in-depth survey of heart transcriptome variation using RNA-sequencing in 97 patients with dilated cardiomyopathy and 108 non-diseased controls. We reveal extensive differences of gene expression and splicing between dilated cardiomyopathy patients and controls, affecting known as well as novel dilated cardiomyopathy genes. Moreover, we show a widespread effect of genetic variation on the regulation of transcription, isoform usage, and allele-specific expression. Systematic annotation of genome-wide association SNPs identifies 60 functional candidate genes for heart phenotypes, representing 20% of all published heart genome-wide association loci. Focusing on the dilated cardiomyopathy phenotype we found that eQTL variants are also enriched for dilated cardiomyopathy genome-wide association signals in two independent cohorts. RNA transcription, splicing, and allele-specific expression are each important determinants of the dilated cardiomyopathy phenotype and are controlled by genetic factors. Our results represent a powerful resource for the field of cardiovascular genetics.

Transcription mapping and expression patterns of genes in the major immediate-early region of Kaposi's sarcoma-associated herpesvirus.

PubMed

Saveliev, Alexei; Zhu, Fan; Yuan, Yan

2002-08-01

Viral immediate-early (IE) genes are the first class of viral genes expressed during primary infection or reactivation from latency. They usually encode regulatory proteins that play crucial roles in viral life cycle. In a previous study, four regions in the KSHV genome were found to be actively transcribed in the immediate-early stage of viral reactivation in primary effusion lymphoma cells. Three immediate-early transcripts were characterized in these regions, as follows: mRNAs for ORF50 (KIE-1), ORF-45 (KIE-2), and ORF K4.2 (KIE-3) (F. X. Zhu, T. Cusano, and Y. Yuan, 1999, J. Virol. 73, 5556-5567). In the present study, we further analyzed the expression of genes in these IE regions in BC-1 and BCBL-1 cells. One of the immediate-early regions (KIE-1) that encompasses ORF50 and other genes was intensively studied to establish a detailed transcription map and expression patterns of genes in this region. This study led to identification of several novel IE transcripts in this region. They include a 2.6-kb mRNA which encodes ORF48/ORF29b, a family of transcripts that are complementary to ORF50 mRNA and a novel K8 IE mRNA of 1.5 kb. Together with the IE mRNA for ORF50 which was identified previously, four immediate-early genes have been mapped to KIE-1 region. Therefore, we would designate KIE-1 the major immediate-early region of KSHV. In addition, we showed that transcription of K8 gene is controlled by two promoters, yielding two transcripts, an immediate-early mRNA of 1.5 kb and a delayed-early mRNA of 1.3 kb.

Antisense transcriptional interference mediates condition-specific gene repression in budding yeast.

PubMed

Nevers, Alicia; Doyen, Antonia; Malabat, Christophe; Néron, Bertrand; Kergrohen, Thomas; Jacquier, Alain; Badis, Gwenael

2018-05-18

Pervasive transcription generates many unstable non-coding transcripts in budding yeast. The transcription of such noncoding RNAs, in particular antisense RNAs (asRNAs), has been shown in a few examples to repress the expression of the associated mRNAs. Yet, such mechanism is not known to commonly contribute to the regulation of a given class of genes. Using a mutant context that stabilized pervasive transcripts, we observed that the least expressed mRNAs during the exponential phase were associated with high levels of asRNAs. These asRNAs also overlapped their corresponding gene promoters with a much higher frequency than average. Interrupting antisense transcription of a subset of genes corresponding to quiescence-enriched mRNAs restored their expression. The underlying mechanism acts in cis and involves several chromatin modifiers. Our results convey that transcription interference represses up to 30% of the 590 least expressed genes, which includes 163 genes with quiescence-enriched mRNAs. We also found that pervasive transcripts constitute a higher fraction of the transcriptome in quiescence relative to the exponential phase, consistent with gene expression itself playing an important role to suppress pervasive transcription. Accordingly, the HIS1 asRNA, normally only present in quiescence, is expressed in exponential phase upon HIS1 mRNA transcription interruption.

RNA Splicing: Regulation and Dysregulation in the Heart.

PubMed

van den Hoogenhof, Maarten M G; Pinto, Yigal M; Creemers, Esther E

2016-02-05

RNA splicing represents a post-transcriptional mechanism to generate multiple functional RNAs or proteins from a single transcript. The evolution of RNA splicing is a prime example of the Darwinian function follows form concept. A mutation that leads to a new mRNA (form) that encodes for a new functional protein (function) is likely to be retained, and this way, the genome has gradually evolved to encode for genes with multiple isoforms, thereby creating an enormously diverse transcriptome. Advances in technologies to characterize RNA populations have led to a better understanding of RNA processing in health and disease. In the heart, alternative splicing is increasingly being recognized as an important layer of post-transcriptional gene regulation. Moreover, the recent identification of several cardiac splice factors, such as RNA-binding motif protein 20 and SF3B1, not only provided important insight into the mechanisms underlying alternative splicing but also revealed how these splicing factors impact functional properties of the heart. Here, we review our current knowledge of alternative splicing in the heart, with a particular focus on the major and minor spliceosome, the factors controlling RNA splicing, and the role of alternative splicing in cardiac development and disease. © 2016 American Heart Association, Inc.

The full-length microRNA cluster in the intron of large latency transcript is associated with the virulence of pseudorabies virus.

PubMed

Wang, Xin; Zhang, Mei-Mei; Yan, Kai; Tang, Qi; Wu, Yi-Quan; He, Wen-Bo; Chen, Huan-Chun; Liu, Zheng-Fei

2018-07-01

Pseudorabies virus (PRV), the etiological pathogen of Aujeszky's disease, belongs to the Alphaherpesvirus subfamily. Large latency transcript (LLT), the most abundant PRV transcript, harbors a ~ 4.6 kb microRNA (miRNA) cluster-encoding intron. To investigate the function of the LLT miRNA cluster during the life cycle of PRV, we generated a miRNA cluster mutation virus (PRV-∆miR cluster) and revertant virus. Analysis of the growth kinetics of PRV-ΔmiR cluster-infected cells revealed significantly smaller plaques and lower titers than the wild-type and revertant viruses. The mutation virus exhibited increased IE180 and decreased EP0 expression. The clinical symptoms observed in mice infected with PRV-ΔmiR cluster revealed that the miRNA cluster is involved in the pathogenesis of PRV. Physical parameters, virus shedding assays, and the SN 50 titers revealed that the miRNA cluster enhances PRV virulence in pigs. Collectively, our findings suggest that the full-length miRNA cluster is involved in PRV replication and virulence. Copyright © 2018 Elsevier Inc. All rights reserved.

PsRobot: a web-based plant small RNA meta-analysis toolbox.

PubMed

Wu, Hua-Jun; Ma, Ying-Ke; Chen, Tong; Wang, Meng; Wang, Xiu-Jie

2012-07-01

Small RNAs (smRNAs) in plants, mainly microRNAs and small interfering RNAs, play important roles in both transcriptional and post-transcriptional gene regulation. The broad application of high-throughput sequencing technology has made routinely generation of bulk smRNA sequences in laboratories possible, thus has significantly increased the need for batch analysis tools. PsRobot is a web-based easy-to-use tool dedicated to the identification of smRNAs with stem-loop shaped precursors (such as microRNAs and short hairpin RNAs) and their target genes/transcripts. It performs fast analysis to identify smRNAs with stem-loop shaped precursors among batch input data and predicts their targets using a modified Smith-Waterman algorithm. PsRobot integrates the expression data of smRNAs in major plant smRNA biogenesis gene mutants and smRNA-associated protein complexes to give clues to the smRNA generation and functional processes. Besides improved specificity, the reliability of smRNA target prediction results can also be evaluated by mRNA cleavage (degradome) data. The cross species conservation statuses and the multiplicity of smRNA target sites are also provided. PsRobot is freely accessible at http://omicslab.genetics.ac.cn/psRobot/.

A growth-dependent transcription initiation factor (TIF-IA) interacting with RNA polymerase I regulates mouse ribosomal RNA synthesis.

PubMed

Schnapp, A; Pfleiderer, C; Rosenbauer, H; Grummt, I

1990-09-01

Control of mouse ribosomal RNA synthesis in response to extracellular signals is mediated by TIF-IA, a regulatory factor whose amount or activity correlates with cell proliferation. Factor TIF-IA interacts with RNA polymerase I (pol I), thus converting it into a transcriptionally active holoenzyme, which is able to initiate specifically at the rDNA promoter in the presence of the other auxiliary transcription initiation factors, designated TIF-IB, TIF-IC and UBF. With regard to several criteria, the growth-dependent factor TIF-IA behaves like a bacterial sigma factor: (i) it associates physically with pol I, (ii) it is required for initiation of transcription, (iii) it is present in limiting amounts and (iv) under certain salt conditions, it is chromatographically separable from the polymerase. In addition, evidence is presented that dephosphorylation of pol I abolishes in vitro transcription initiation from the ribosomal gene promoter without significantly affecting the polymerizing activity of the enzyme at nonspecific templates. The involvement of both a regulatory factor and post-translational modification of the transcribing enzyme provides an efficient and versatile mechanism of rDNA transcription regulation which enables the cell to adapt ribosome synthesis rapidly to a variety of extracellular signals.

RNA/DNA Hybrid Interactome Identifies DXH9 as a Molecular Player in Transcriptional Termination and R-Loop-Associated DNA Damage.

PubMed

Cristini, Agnese; Groh, Matthias; Kristiansen, Maiken S; Gromak, Natalia

2018-05-08

R-loops comprise an RNA/DNA hybrid and displaced single-stranded DNA. They play important biological roles and are implicated in pathology. Even so, proteins recognizing these structures are largely undefined. Using affinity purification with the S9.6 antibody coupled to mass spectrometry, we defined the RNA/DNA hybrid interactome in HeLa cells. This consists of known R-loop-associated factors SRSF1, FACT, and Top1, and yet uncharacterized interactors, including helicases, RNA processing, DNA repair, and chromatin factors. We validate specific examples of these interactors and characterize their involvement in R-loop biology. A top candidate DHX9 helicase promotes R-loop suppression and transcriptional termination. DHX9 interacts with PARP1, and both proteins prevent R-loop-associated DNA damage. DHX9 and other interactome helicases are overexpressed in cancer, linking R-loop-mediated DNA damage and disease. Our RNA/DNA hybrid interactome provides a powerful resource to study R-loop biology in health and disease. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

The contribution of co-transcriptional RNA:DNA hybrid structures to DNA damage and genome instability

PubMed Central

Hamperl, Stephan; Cimprich, Karlene A.

2014-01-01

Accurate DNA replication and DNA repair are crucial for the maintenance of genome stability, and it is generally accepted that failure of these processes is a major source of DNA damage in cells. Intriguingly, recent evidence suggests that DNA damage is more likely to occur at genomic loci with high transcriptional activity. Furthermore, loss of certain RNA processing factors in eukaryotic cells is associated with increased formation of co-transcriptional RNA:DNA hybrid structures known as R-loops, resulting in double-strand breaks (DSBs) and DNA damage. However, the molecular mechanisms by which R-loop structures ultimately lead to DNA breaks and genome instability is not well understood. In this review, we summarize the current knowledge about the formation, recognition and processing of RNA:DNA hybrids, and discuss possible mechanisms by which these structures contribute to DNA damage and genome instability in the cell. PMID:24746923

Nuclear export of human hepatitis B virus core protein and pregenomic RNA depends on the cellular NXF1-p15 machinery.

PubMed

Yang, Ching-Chun; Huang, Er-Yi; Li, Hung-Cheng; Su, Pei-Yi; Shih, Chiaho

2014-01-01

Hepatitis B virus (HBV) core protein (HBc) can shuttle between nucleus and cytoplasm. Cytoplasm-predominant HBc is clinically associated with severe liver inflammation. Previously, we found that HBc arginine-rich domain (ARD) can associate with a host factor NXF1 (TAP) by coimmunoprecipitation. It is well known that NXF1-p15 heterodimer can serve as a major export receptor of nuclear mRNA as a ribonucleoprotein complex (RNP). In the NXF1-p15 pathway, TREX (transcription/export) complex plays an important role in coupling nuclear pre-mRNA processing with mRNA export in mammalian cells. Here, we tested the hypothesis whether HBc and HBV specific RNA can be exported via the TREX and NXF1-p15 mediated pathway. We demonstrated here that HBc can physically and specifically associate with TREX components, and the NXF1-p15 export receptor by coimmunoprecipitation. Accumulation of HBc protein in the nucleus can be induced by the interference with TREX and NXF1-p15 mediated RNA export machinery. HBV transcripts encodes a non-spliced 3.5 kb pregenomic RNA (pgRNA) which can serve as a template for reverse transcription. Cytoplasmic HBV pgRNA appeared to be reduced by siRNA treatment specific for the NXF1-p15 complex by quantitative RT-qPCR and Northern blot analyses. This result suggests that the pgRNA was also exported via the NXF1-p15 machinery. We entertain the hypothesis that HBc protein can be exported as an RNP cargo via the mRNA export pathway by hijacking the TREX and NXF1-p15 complex. In our current and previous studies, HBc is not required for pgRNA accumulation in the cytoplasm. Furthermore, HBc ARD can mediate nuclear export of a chimeric protein containing HBc ARD in a pgRNA-independent manner. Taken together, it suggests that while both pgRNA and HBc protein exports are dependent on NXF1-p15, they are using the same export machinery in a manner independent of each other.

Small interfering RNAs from bidirectional transcripts of GhMML3_A12 regulate cotton fiber development.

PubMed

Wan, Qun; Guan, Xueying; Yang, Nannan; Wu, Huaitong; Pan, Mengqiao; Liu, Bingliang; Fang, Lei; Yang, Shouping; Hu, Yan; Ye, Wenxue; Zhang, Hua; Ma, Peiyong; Chen, Jiedan; Wang, Qiong; Mei, Gaofu; Cai, Caiping; Yang, Donglei; Wang, Jiawei; Guo, Wangzhen; Zhang, Wenhua; Chen, Xiaoya; Zhang, Tianzhen

2016-06-01

Natural antisense transcripts (NATs) are commonly observed in eukaryotic genomes, but only a limited number of such genes have been identified as being involved in gene regulation in plants. In this research, we investigated the function of small RNA derived from a NAT in fiber cell development. Using a map-based cloning strategy for the first time in tetraploid cotton, we cloned a naked seed mutant gene (N1 ) encoding a MYBMIXTA-like transcription factor 3 (MML3)/GhMYB25-like in chromosome A12, GhMML3_A12, that is associated with fuzz fiber development. The extremely low expression of GhMML3_A12 in N1 is associated with NAT production, driven by its 3' antisense promoter, as indicated by the promoter-driven histochemical staining assay. In addition, small RNA deep sequencing analysis suggested that the bidirectional transcriptions of GhMML3_A12 form double-stranded RNAs and generate 21-22 nt small RNAs. Therefore, in a fiber-specific manner, small RNA derived from the GhMML3_A12 locus can mediate GhMML3_A12 mRNA self-cleavage and result in the production of naked seeds followed by lint fiber inhibition in N1 plants. The present research reports the first observation of gene-mediated NATs and siRNA directly controlling fiber development in cotton. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Sls1p is a membrane-bound regulator of transcription-coupled processes involved in Saccharomyces cerevisiae mitochondrial gene expression.

PubMed Central

Bryan, Anthony C; Rodeheffer, Matthew S; Wearn, Christopher M; Shadel, Gerald S

2002-01-01

Mitochondrial translation is largely membrane-associated in S. cerevisiae. Recently, we discovered that the matrix protein Nam1p binds the amino-terminal domain of yeast mtRNA polymerase to couple translation and/or RNA-processing events to transcription. To gain additional insight into these transcription-coupled processes, we performed a genetic screen for genes that suppress the petite phenotype of a point mutation in mtRNA polymerase (rpo41-R129D) when overexpressed. One suppressor identified in this screen was SLS1, which encodes a mitochondrial membrane protein required for assembly of respiratory-chain enzyme complexes III and IV. The mtRNA-processing defects associated with the rpo41-R129D mutation were corrected in the suppressed strain, linking Sls1p to a pathway that includes mtRNA polymerase and Nam1p. This was supported by the observation that SLS1 overexpression rescued the petite phenotype of a NAM1 null mutation. In contrast, overexpression of Nam1p did not rescue the petite phenotype of a SLS1 null mutation, indicating that Nam1p and Sls1p are not functionally redundant but rather exist in an ordered pathway. On the basis of these data, a model in which Nam1p coordinates the delivery of newly synthesized transcripts to the membrane, where Sls1p directs or regulates their subsequent handling by membrane-bound factors involved in translation, is proposed. PMID:11805046

TAF(II)250: a transcription toolbox.

PubMed

Wassarman, D A; Sauer, F

2001-08-01

Activation of RNA-polymerase-II-dependent transcription involves conversion of signals provided by gene-specific activator proteins into the synthesis of messenger RNA. This conversion requires dynamic structural changes in chromatin and assembly of general transcription factors (GTFs) and RNA polymerase II at core promoter sequence elements surrounding the transcription start site of genes. One hallmark of transcriptional activation is the interaction of DNA-bound activators with coactivators such as the TATA-box binding protein (TBP)-associated factors (TAF(II)s) within the GTF TFIID. TAF(II)250 possesses a variety of activities that are likely to contribute to the initial steps of RNA polymerase II transcription. TAF(II)250 is a scaffold for assembly of other TAF(II)s and TBP into TFIID, TAF(II)250 binds activators to recruit TFIID to particular promoters, TAF(II)250 regulates binding of TBP to DNA, TAF(II)250 binds core promoter initiator elements, TAF(II)250 binds acetylated lysine residues in core histones, and TAF(II)250 possesses protein kinase, ubiquitin-activating/conjugating and acetylase activities that modify histones and GTFs. We speculate that these activities achieve two goals--(1) they aid in positioning and stabilizing TFIID at particular promoters, and (2) they alter chromatin structure at the promoter to allow assembly of GTFs--and we propose a model for how TAF(II)250 converts activation signals into active transcription.

Intergenic Transcriptional Interference Is Blocked by RNA Polymerase III Transcription Factor TFIIIB in Saccharomyces cerevisiae

PubMed Central

Korde, Asawari; Rosselot, Jessica M.; Donze, David

2014-01-01

The major function of eukaryotic RNA polymerase III is to transcribe transfer RNA, 5S ribosomal RNA, and other small non-protein-coding RNA molecules. Assembly of the RNA polymerase III complex on chromosomal DNA requires the sequential binding of transcription factor complexes TFIIIC and TFIIIB. Recent evidence has suggested that in addition to producing RNA transcripts, chromatin-assembled RNA polymerase III complexes may mediate additional nuclear functions that include chromatin boundary, nucleosome phasing, and general genome organization activities. This study provides evidence of another such “extratranscriptional” activity of assembled RNA polymerase III complexes, which is the ability to block progression of intergenic RNA polymerase II transcription. We demonstrate that the RNA polymerase III complex bound to the tRNA gene upstream of the Saccharomyces cerevisiae ATG31 gene protects the ATG31 promoter against readthrough transcriptional interference from the upstream noncoding intergenic SUT467 transcription unit. This protection is predominately mediated by binding of the TFIIIB complex. When TFIIIB binding to this tRNA gene is weakened, an extended SUT467–ATG31 readthrough transcript is produced, resulting in compromised ATG31 translation. Since the ATG31 gene product is required for autophagy, strains expressing the readthrough transcript exhibit defective autophagy induction and reduced fitness under autophagy-inducing nitrogen starvation conditions. Given the recent discovery of widespread pervasive transcription in all forms of life, protection of neighboring genes from intergenic transcriptional interference may be a key extratranscriptional function of assembled RNA polymerase III complexes and possibly other DNA binding proteins. PMID:24336746

Increased Transcript Complexity in Genes Associated with Chronic Obstructive Pulmonary Disease

PubMed Central

Lackey, Lela; McArthur, Evonne; Laederach, Alain

2015-01-01

Genome-wide association studies aim to correlate genotype with phenotype. Many common diseases including Type II diabetes, Alzheimer’s, Parkinson’s and Chronic Obstructive Pulmonary Disease (COPD) are complex genetic traits with hundreds of different loci that are associated with varied disease risk. Identifying common features in the genes associated with each disease remains a challenge. Furthermore, the role of post-transcriptional regulation, and in particular alternative splicing, is still poorly understood in most multigenic diseases. We therefore compiled comprehensive lists of genes associated with Type II diabetes, Alzheimer’s, Parkinson’s and COPD in an attempt to identify common features of their corresponding mRNA transcripts within each gene set. The SERPINA1 gene is a well-recognized genetic risk factor of COPD and it produces 11 transcript variants, which is exceptional for a human gene. This led us to hypothesize that other genes associated with COPD, and complex disorders in general, are highly transcriptionally diverse. We found that COPD-associated genes have a statistically significant enrichment in transcript complexity stemming from a disproportionately high level of alternative splicing, however, Type II Diabetes, Alzheimer’s and Parkinson’s disease genes were not significantly enriched. We also identified a subset of transcriptionally complex COPD-associated genes (~40%) that are differentially expressed between mild, moderate and severe COPD. Although the genes associated with other lung diseases are not extensively documented, we found preliminary data that idiopathic pulmonary disease genes, but not cystic fibrosis modulators, are also more transcriptionally complex. Interestingly, complex COPD transcripts are more often the product of alternative acceptor site usage. To verify the biological importance of these alternative transcripts, we used RNA-sequencing analyses to determine that COPD-associated genes are frequently expressed in lung and liver tissues and are regulated in a tissue-specific manner. Additionally, many complex COPD-associated genes are spliced differently between COPD and non-COPD patients. Our analysis therefore suggests that post-transcriptional regulation, particularly alternative splicing, is an important feature specific to COPD disease etiology that warrants further investigation. PMID:26480348

Genes uniquely expressed in human growth plate chondrocytes uncover a distinct regulatory network.

PubMed

Li, Bing; Balasubramanian, Karthika; Krakow, Deborah; Cohn, Daniel H

2017-12-20

Chondrogenesis is the earliest stage of skeletal development and is a highly dynamic process, integrating the activities and functions of transcription factors, cell signaling molecules and extracellular matrix proteins. The molecular mechanisms underlying chondrogenesis have been extensively studied and multiple key regulators of this process have been identified. However, a genome-wide overview of the gene regulatory network in chondrogenesis has not been achieved. In this study, employing RNA sequencing, we identified 332 protein coding genes and 34 long non-coding RNA (lncRNA) genes that are highly selectively expressed in human fetal growth plate chondrocytes. Among the protein coding genes, 32 genes were associated with 62 distinct human skeletal disorders and 153 genes were associated with skeletal defects in knockout mice, confirming their essential roles in skeletal formation. These gene products formed a comprehensive physical interaction network and participated in multiple cellular processes regulating skeletal development. The data also revealed 34 transcription factors and 11,334 distal enhancers that were uniquely active in chondrocytes, functioning as transcriptional regulators for the cartilage-selective genes. Our findings revealed a complex gene regulatory network controlling skeletal development whereby transcription factors, enhancers and lncRNAs participate in chondrogenesis by transcriptional regulation of key genes. Additionally, the cartilage-selective genes represent candidate genes for unsolved human skeletal disorders.

Dynamics and Function of Nuclear Bodies during Embryogenesis.

PubMed

Arias Escayola, Dahyana; Neugebauer, Karla M

2018-05-01

Nuclear bodies are RNA-rich membraneless organelles in the cell nucleus that concentrate specific sets of nuclear proteins and RNA-protein complexes. Nuclear bodies such as the nucleolus, Cajal body (CB), and the histone locus body (HLB) concentrate factors required for nuclear steps of RNA processing. Formation of these nuclear bodies occurs on genomic loci and is frequently associated with active sites of transcription. Whether nuclear body formation is dependent on a particular gene element, an active process such as transcription, or the nascent RNA present at gene loci is a topic of debate. Recently, this question has been addressed through studies in model organisms and their embryos. The switch from maternally provided RNA and protein to zygotic gene products in early embryos has been well characterized in a variety of organisms. This process, termed maternal-to-zygotic transition, provides an excellent model for studying formation of nuclear bodies before, during, and after the transcriptional activation of the zygotic genome. Here, we review findings in embryos that reveal key principles in the study of the formation and function of nucleoli, CBs, and HLBs. We propose that while particular gene elements may contribute to formation of these nuclear bodies, active transcription promotes maturation of nuclear bodies and efficient RNA processing within them.

Extensive Use of RNA-Binding Proteins in Drosophila Sensory Neuron Dendrite Morphogenesis

PubMed Central

Olesnicky, Eugenia C.; Killian, Darrell J.; Garcia, Evelyn; Morton, Mary C.; Rathjen, Alan R.; Sola, Ismail E.; Gavis, Elizabeth R.

2013-01-01

The large number of RNA-binding proteins and translation factors encoded in the Drosophila and other metazoan genomes predicts widespread use of post-transcriptional regulation in cellular and developmental processes. Previous studies identified roles for several RNA-binding proteins in dendrite branching morphogenesis of Drosophila larval sensory neurons. To determine the larger contribution of post-transcriptional gene regulation to neuronal morphogenesis, we conducted an RNA interference screen to identify additional Drosophila proteins annotated as either RNA-binding proteins or translation factors that function in producing the complex dendritic trees of larval class IV dendritic arborization neurons. We identified 88 genes encoding such proteins whose knockdown resulted in aberrant dendritic morphology, including alterations in dendritic branch number, branch length, field size, and patterning of the dendritic tree. In particular, splicing and translation initiation factors were associated with distinct and characteristic phenotypes, suggesting that different morphogenetic events are best controlled at specific steps in post-transcriptional messenger RNA metabolism. Many of the factors identified in the screen have been implicated in controlling the subcellular distributions and translation of maternal messenger RNAs; thus, common post-transcriptional regulatory strategies may be used in neurogenesis and in the generation of asymmetry in the female germline and embryo. PMID:24347626

A hyperactive transcriptional state marks genome reactivation at the mitosis-G1 transition.

PubMed

Hsiung, Chris C-S; Bartman, Caroline R; Huang, Peng; Ginart, Paul; Stonestrom, Aaron J; Keller, Cheryl A; Face, Carolyne; Jahn, Kristen S; Evans, Perry; Sankaranarayanan, Laavanya; Giardine, Belinda; Hardison, Ross C; Raj, Arjun; Blobel, Gerd A

2016-06-15

During mitosis, RNA polymerase II (Pol II) and many transcription factors dissociate from chromatin, and transcription ceases globally. Transcription is known to restart in bulk by telophase, but whether de novo transcription at the mitosis-G1 transition is in any way distinct from later in interphase remains unknown. We tracked Pol II occupancy genome-wide in mammalian cells progressing from mitosis through late G1. Unexpectedly, during the earliest rounds of transcription at the mitosis-G1 transition, ∼50% of active genes and distal enhancers exhibit a spike in transcription, exceeding levels observed later in G1 phase. Enhancer-promoter chromatin contacts are depleted during mitosis and restored rapidly upon G1 entry but do not spike. Of the chromatin-associated features examined, histone H3 Lys27 acetylation levels at individual loci in mitosis best predict the mitosis-G1 transcriptional spike. Single-molecule RNA imaging supports that the mitosis-G1 transcriptional spike can constitute the maximum transcriptional activity per DNA copy throughout the cell division cycle. The transcriptional spike occurs heterogeneously and propagates to cell-to-cell differences in mature mRNA expression. Our results raise the possibility that passage through the mitosis-G1 transition might predispose cells to diverge in gene expression states. © 2016 Hsiung et al.; Published by Cold Spring Harbor Laboratory Press.

RNA Helicase DDX1 Converts RNA G-Quadruplex Structures into R-Loops to Promote IgH Class Switch Recombination.

PubMed

Ribeiro de Almeida, Claudia; Dhir, Somdutta; Dhir, Ashish; Moghaddam, Amin E; Sattentau, Quentin; Meinhart, Anton; Proudfoot, Nicholas J

2018-05-17

Class switch recombination (CSR) at the immunoglobulin heavy-chain (IgH) locus is associated with the formation of R-loop structures over switch (S) regions. While these often occur co-transcriptionally between nascent RNA and template DNA, we now show that they also form as part of a post-transcriptional mechanism targeting AID to IgH S-regions. This depends on the RNA helicase DDX1 that is also required for CSR in vivo. DDX1 binds to G-quadruplex (G4) structures present in intronic switch transcripts and converts them into S-region R-loops. This in turn targets the cytidine deaminase enzyme AID to S-regions so promoting CSR. Notably R-loop levels over S-regions are diminished by chemical stabilization of G4 RNA or by the expression of a DDX1 ATPase-deficient mutant that acts as a dominant-negative protein to reduce CSR efficiency. In effect, we provide evidence for how S-region transcripts interconvert between G4 and R-loop structures to promote CSR in the IgH locus. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

SON and its alternatively spliced isoforms control MLL complex-mediated H3K4me3 and transcription of leukemia-associated genes

PubMed Central

Kim, Jung-Hyun; Baddoo, Melody C.; Park, Eun Young; Stone, Joshua K.; Park, Hyeonsoo; Butler, Thomas W.; Huang, Gang; Yan, Xiaomei; Pauli-Behn, Florencia; Myers, Richard M.; Tan, Ming; Flemington, Erik K.; Lim, Ssang-Taek; Erin Ahn, Eun-Young

2016-01-01

SUMMARY Dysregulation of MLL complex-mediated histone methylation plays a pivotal role in gene expression associated with diseases, but little is known about cellular factors modulating MLL complex activity. Here, we report that SON, previously known as an RNA splicing factor, controls MLL complex-mediated transcriptional initiation. SON binds to DNA near transcription start sites, interacts with menin, and inhibits MLL complex assembly, resulting in decreased H3K4me3 and transcriptional repression. Importantly, alternatively spliced short isoforms of SON are markedly upregulated in acute myeloid leukemia. The short isoforms compete with full-length SON for chromatin occupancy, but lack the menin-binding ability, thereby antagonizing full-length SON function in transcriptional repression while not impairing full-length SON-mediated RNA splicing. Furthermore, overexpression of a short isoform of SON enhances replating potential of hematopoietic progenitors. Our findings define SON as a fine-tuner of the MLL-menin interaction and reveal short SON overexpression as a marker indicating aberrant transcriptional initiation in leukemia. PMID:26990989

Polysome Fractionation to Analyze mRNA Distribution Profiles.

PubMed

Panda, Amaresh C; Martindale, Jennifer L; Gorospe, Myriam

2017-02-05

Eukaryotic cells adapt to changes in external or internal signals by precisely modulating the expression of specific gene products. The expression of protein-coding genes is controlled at the transcriptional and post-transcriptional levels. Among the latter steps, the regulation of translation is particularly important in cellular processes that require rapid changes in protein expression patterns. The translational efficiency of mRNAs is altered by RNA-binding proteins (RBPs) and noncoding (nc)RNAs such as microRNAs (Panda et al. , 2014a and 2014b; Abdelmohsen et al. , 2014). The impact of factors that regulate selective mRNA translation is a critical question in RNA biology. Polyribosome (polysome) fractionation analysis is a powerful method to assess the association of ribosomes with a given mRNA. It provides valuable information about the translational status of that mRNA, depending on the number of ribosomes with which they are associated, and identifies mRNAs that are not translated (Panda et al. , 2016). mRNAs associated with many ribosomes form large polysomes that are predicted to be actively translated, while mRNAs associated with few or no ribosomes are expected to be translated poorly if at all. In sum, polysome fractionation analysis allows the direct determination of translation efficiencies at the level of the whole transcriptome as well as individual mRNAs.

Structure of the initiation-competent RNA polymerase I and its implication for transcription

NASA Astrophysics Data System (ADS)

Pilsl, Michael; Crucifix, Corinne; Papai, Gabor; Krupp, Ferdinand; Steinbauer, Robert; Griesenbeck, Joachim; Milkereit, Philipp; Tschochner, Herbert; Schultz, Patrick

2016-07-01

Eukaryotic RNA polymerase I (Pol I) is specialized in rRNA gene transcription synthesizing up to 60% of cellular RNA. High level rRNA production relies on efficient binding of initiation factors to the rRNA gene promoter and recruitment of Pol I complexes containing initiation factor Rrn3. Here, we determine the cryo-EM structure of the Pol I-Rrn3 complex at 7.5 Å resolution, and compare it with Rrn3-free monomeric and dimeric Pol I. We observe that Rrn3 contacts the Pol I A43/A14 stalk and subunits A190 and AC40, that association re-organizes the Rrn3 interaction interface, thereby preventing Pol I dimerization; and Rrn3-bound and monomeric Pol I differ from the dimeric enzyme in cleft opening, and localization of the A12.2 C-terminus in the active centre. Our findings thus support a dual role for Rrn3 in transcription initiation to stabilize a monomeric initiation competent Pol I and to drive pre-initiation complex formation.

Effects of spaceflight on murine skeletal muscle gene expression

PubMed Central

Allen, David L.; Bandstra, Eric R.; Harrison, Brooke C.; Thorng, Seiha; Stodieck, Louis S.; Kostenuik, Paul J.; Morony, Sean; Lacey, David L.; Hammond, Timothy G.; Leinwand, Leslie L.; Argraves, W. Scott; Bateman, Ted A.; Barth, Jeremy L.

2009-01-01

Spaceflight results in a number of adaptations to skeletal muscle, including atrophy and shifts toward faster muscle fiber types. To identify changes in gene expression that may underlie these adaptations, we used both microarray expression analysis and real-time polymerase chain reaction to quantify shifts in mRNA levels in the gastrocnemius from mice flown on the 11-day, 19-h STS-108 shuttle flight and from normal gravity controls. Spaceflight data also were compared with the ground-based unloading model of hindlimb suspension, with one group of pure suspension and one of suspension followed by 3.5 h of reloading to mimic the time between landing and euthanization of the spaceflight mice. Analysis of microarray data revealed that 272 mRNAs were significantly altered by spaceflight, the majority of which displayed similar responses to hindlimb suspension, whereas reloading tended to counteract these responses. Several mRNAs altered by spaceflight were associated with muscle growth, including the phosphatidylinositol 3-kinase regulatory subunit p85α, insulin response substrate-1, the forkhead box O1 transcription factor, and MAFbx/atrogin1. Moreover, myostatin mRNA expression tended to increase, whereas mRNA levels of the myostatin inhibitor FSTL3 tended to decrease, in response to spaceflight. In addition, mRNA levels of the slow oxidative fiber-associated transcriptional coactivator peroxisome proliferator-associated receptor (PPAR)-γ coactivator-1α and the transcription factor PPAR-α were significantly decreased in spaceflight gastrocnemius. Finally, spaceflight resulted in a significant decrease in levels of the microRNA miR-206. Together these data demonstrate that spaceflight induces significant changes in mRNA expression of genes associated with muscle growth and fiber type. PMID:19074574

Early transcriptional and epigenetic regulation of CD8+ T cell differentiation revealed by single-cell RNA-seq

PubMed Central

Kakaradov, Boyko; Arsenio, Janilyn; Widjaja, Christella E.; He, Zhaoren; Aigner, Stefan; Metz, Patrick J.; Yu, Bingfei; Wehrens, Ellen J.; Lopez, Justine; Kim, Stephanie H.; Zuniga, Elina I.; Goldrath, Ananda W.; Chang, John T.; Yeo, Gene W.

2017-01-01

SUMMARY During microbial infection, responding CD8+ T lymphocytes differentiate into heterogeneous subsets that together provide immediate and durable protection. To elucidate the dynamic transcriptional changes that underlie this process, we applied a single-cell RNA sequencing approach and analyzed individual CD8+ T lymphocytes sequentially throughout the course of a viral infection in vivo. Our analyses revealed a striking transcriptional divergence among cells that had undergone their first division and identified previously unknown molecular determinants controlling CD8+ T lymphocyte fate specification. These findings suggest a model of terminal effector cell differentiation initiated by an early burst of transcriptional activity and subsequently refined by epigenetic silencing of transcripts associated with memory lymphocytes, highlighting the power and necessity of single-cell approaches. PMID:28218746

A system biology approach for understanding the miRNA regulatory network in colon rectal cancer.

PubMed

Pradhan, Meeta; Nagulapalli, Kshithija; Ledford, Lakenvia; Pandit, Yogesh; Palakal, Mathew

2015-01-01

In this paper we present a systems biology approach to the understanding of the miRNA-regulatory network in colon rectal cancer. An initial set of significant genes in Colon Rectal Cancer (CRC) were obtained by mining relevant literature. An initial set of cancer-related miRNAs were obtained from three databases: miRBase, miRWalk, Targetscan and GEO microarray experiment. First principle methods were then used to generate the global miRNA-gene network. Significant miRNAs and associated transcription factors in the global miRNA-gene network were identified using topological and sub-graph analyses. Eleven novel miRNAs were identified and three of the novel miRNAs, hsa-miR-630, hsa-miR-100 and hsa-miR-99a, were further analysed to elucidate their role in CRC. The proposed methodology effectively made use of literature data and was able to show novel, significant miRNA-transcription associations in CRC.

Non-coding RNA may be associated with cytoplasmic male sterility in Silene vulgaris

PubMed Central

Stone, James D.; Koloušková, Pavla; Sloan, Daniel B.

2017-01-01

Abstract Cytoplasmic male sterility (CMS) is a widespread phenomenon in flowering plants caused by mitochondrial (mt) genes. CMS genes typically encode novel proteins that interfere with mt functions and can be silenced by nuclear fertility-restorer genes. Although the molecular basis of CMS is well established in a number of crop systems, our understanding of it in natural populations is far more limited. To identify CMS genes in a gynodioecious plant, Silene vulgaris, we constructed mt transcriptomes and compared transcript levels and RNA editing patterns in floral bud tissue from female and hermaphrodite full siblings. The transcriptomes from female and hermaphrodite individuals were very similar overall with respect to variation in levels of transcript abundance across the genome, the extent of RNA editing, and the order in which RNA editing and intron splicing events occurred. We found only a single genomic region that was highly overexpressed and differentially edited in females relative to hermaphrodites. This region is not located near any other transcribed elements and lacks an open-reading frame (ORF) of even moderate size. To our knowledge, this transcript would represent the first non-coding mt RNA associated with CMS in plants and is, therefore, an important target for future functional validation studies. PMID:28369520

Genome-wide mRNA processing in methanogenic archaea reveals post-transcriptional regulation of ribosomal protein synthesis

PubMed Central

Qi, Lei; Yue, Lei; Feng, Deqin; Qi, Fengxia

2017-01-01

Abstract Unlike stable RNAs that require processing for maturation, prokaryotic cellular mRNAs generally follow an ‘all-or-none’ pattern. Herein, we used a 5΄ monophosphate transcript sequencing (5΄P-seq) that specifically captured the 5΄-end of processed transcripts and mapped the genome-wide RNA processing sites (PSSs) in a methanogenic archaeon. Following statistical analysis and stringent filtration, we identified 1429 PSSs, among which 23.5% and 5.4% were located in 5΄ untranslated region (uPSS) and intergenic region (iPSS), respectively. A predominant uridine downstream PSSs served as a processing signature. Remarkably, 5΄P-seq detected overrepresented uPSS and iPSS in the polycistronic operons encoding ribosomal proteins, and the majority upstream and proximal ribosome binding sites, suggesting a regulatory role of processing on translation initiation. The processed transcripts showed increased stability and translation efficiency. Particularly, processing within the tricistronic transcript of rplA-rplJ-rplL enhanced the translation of rplL, which can provide a driving force for the 1:4 stoichiometry of L10 to L12 in the ribosome. Growth-associated mRNA processing intensities were also correlated with the cellular ribosomal protein levels, thereby suggesting that mRNA processing is involved in tuning growth-dependent ribosome synthesis. In conclusion, our findings suggest that mRNA processing-mediated post-transcriptional regulation is a potential mechanism of ribosomal protein synthesis and stoichiometry. PMID:28520982

Hypoxia regulates alternative splicing of HIF and non-HIF target genes.

PubMed

Sena, Johnny A; Wang, Liyi; Heasley, Lynn E; Hu, Cheng-Jun

2014-09-01

Hypoxia is a common characteristic of many solid tumors. The hypoxic microenvironment stabilizes hypoxia-inducible transcription factor 1α (HIF1α) and 2α (HIF2α/EPAS1) to activate gene transcription, which promotes tumor cell survival. The majority of human genes are alternatively spliced, producing RNA isoforms that code for functionally distinct proteins. Thus, an effective hypoxia response requires increased HIF target gene expression as well as proper RNA splicing of these HIF-dependent transcripts. However, it is unclear if and how hypoxia regulates RNA splicing of HIF targets. This study determined the effects of hypoxia on alternative splicing (AS) of HIF and non-HIF target genes in hepatocellular carcinoma cells and characterized the role of HIF in regulating AS of HIF-induced genes. The results indicate that hypoxia generally promotes exon inclusion for hypoxia-induced, but reduces exon inclusion for hypoxia-reduced genes. Mechanistically, HIF activity, but not hypoxia per se is found to be necessary and sufficient to increase exon inclusion of several HIF targets, including pyruvate dehydrogenase kinase 1 (PDK1). PDK1 splicing reporters confirm that transcriptional activation by HIF is sufficient to increase exon inclusion of PDK1 splicing reporter. In contrast, transcriptional activation of a PDK1 minigene by other transcription factors in the absence of endogenous HIF target gene activation fails to alter PDK1 RNA splicing. This study demonstrates a novel function of HIF in regulating RNA splicing of HIF target genes. ©2014 American Association for Cancer Research.

A long noncoding RNA, lincRNA-Tnfaip3, acts as a coregulator of NF-κB to modulate inflammatory gene transcription in mouse macrophages.

PubMed

Ma, Shibin; Ming, Zhenping; Gong, Ai-Yu; Wang, Yang; Chen, Xiqiang; Hu, Guoku; Zhou, Rui; Shibata, Annemarie; Swanson, Patrick C; Chen, Xian-Ming

2017-03-01

Long intergenic noncoding RNAs (lincRNAs) are long noncoding transcripts (>200 nt) from the intergenic regions of annotated protein-coding genes. We report here that the lincRNA gene lincRNA-Tnfaip3 , located at mouse chromosome 10 proximal to the tumor necrosis factor α-induced protein 3 ( Tnfaip3 ) gene, is an early-primary response gene controlled by nuclear factor-κB (NF-κB) signaling in murine macrophages. Functionally, lincRNA- Tnfaip3 appears to mediate both the activation and repression of distinct classes of inflammatory genes in macrophages. Specifically, induction of lincRNA-Tnfaip3 is required for the transactivation of NF-κB-regulated inflammatory genes in response to bacterial LPSs stimulation. LincRNA-Tnfaip3 physically interacts with the high-mobility group box 1 (Hmgb1), assembling a NF-κB/Hmgb1/lincRNA-Tnfaip3 complex in macrophages after LPS stimulation. This resultant NF-κB/Hmgb1/lincRNA-Tnfaip3 complex can modulate Hmgb1-associated histone modifications and, ultimately, transactivation of inflammatory genes in mouse macrophages in response to microbial challenge. Therefore, our data indicate a new regulatory role of NF-κB-induced lincRNA-Tnfaip3 to act as a coactivator of NF-κB for the transcription of inflammatory genes in innate immune cells through modulation of epigenetic chromatin remodeling.-Ma, S., Ming, Z., Gong, A.-Y., Wang, Y., Chen, X., Hu, G., Zhou, R., Shibata, A., Swanson, P. C., Chen, X.-M. A long noncoding RNA, LincRNA-Tnfaip3, acts as a coregulator of NF-κB to modulate inflammatory gene transcription in mouse macrophages. © FASEB.

Delayed translational silencing of ceruloplasmin transcript in gamma interferon-activated U937 monocytic cells: role of the 3' untranslated region

NASA Technical Reports Server (NTRS)

Mazumder, B.; Fox, P. L.

1999-01-01

Ceruloplasmin (Cp) is an acute-phase protein with ferroxidase, amine oxidase, and pro- and antioxidant activities. The primary site of Cp synthesis in human adults is the liver, but it is also synthesized by cells of monocytic origin. We have shown that gamma interferon (IFN-gamma) induces the synthesis of Cp mRNA and protein in monocytic cells. We now report that the induced synthesis of Cp is terminated by a mechanism involving transcript-specific translational repression. Cp protein synthesis in U937 cells ceased after 16 h even in the presence of abundant Cp mRNA. RNA isolated from cells treated with IFN-gamma for 24 h exhibited a high in vitro translation rate, suggesting that the transcript was not defective. Ribosomal association of Cp mRNA was examined by sucrose centrifugation. When Cp synthesis was high, i.e., after 8 h of IFN-gamma treatment, Cp mRNA was primarily associated with polyribosomes. However, after 24 h, when Cp synthesis was low, Cp mRNA was primarily in the nonpolyribosomal fraction. Cytosolic extracts from cells treated with IFN-gamma for 24 h, but not for 8 h, contained a factor which blocked in vitro Cp translation. Inhibitor expression was cell type specific and present in extracts of human cells of myeloid origin, but not in several nonmyeloid cells. The inhibitory factor bound to the 3' untranslated region (3'-UTR) of Cp mRNA, as shown by restoration of in vitro translation by synthetic 3'-UTR added as a "decoy" and detection of a binding complex by RNA gel shift analysis. Deletion mapping of the Cp 3'-UTR indicated an internal 100-nucleotide region of the Cp 3'-UTR that was required for complex formation as well as for silencing of translation. Although transcript-specific translational control is common during development and differentiation and global translational control occurs during responses to cytokines and stress, to our knowledge, this is the first report of translational silencing of a specific transcript following cytokine activation.

UBF complexes with phosphatidylinositol 4,5-bisphosphate in nucleolar organizer regions regardless of ongoing RNA polymerase I activity

PubMed Central

Sobol, Margarita; Yildirim, Sukriye; Philimonenko, Vlada V; Marášek, Pavel; Castaño, Enrique; Hozák, Pavel

2013-01-01

To maintain growth and division, cells require a large-scale production of rRNAs which occurs in the nucleolus. Recently, we have shown the interaction of nucleolar phosphatidylinositol 4,5-bisphosphate (PIP2) with proteins involved in rRNA transcription and processing, namely RNA polymerase I (Pol I), UBF, and fibrillarin. Here we extend the study by investigating transcription-related localization of PIP2 in regards to transcription and processing complexes of Pol I. To achieve this, we used either physiological inhibition of transcription during mitosis or inhibition by treatment the cells with actinomycin D (AMD) or 5,6-dichloro-1β-d-ribofuranosyl-benzimidazole (DRB). We show that PIP2 is associated with Pol I subunits and UBF in a transcription-independent manner. On the other hand, PIP2/fibrillarin colocalization is dependent on the production of rRNA. These results indicate that PIP2 is required not only during rRNA production and biogenesis, as we have shown before, but also plays a structural role as an anchor for the Pol I pre-initiation complex during the cell cycle. We suggest that throughout mitosis, PIP2 together with UBF is involved in forming and maintaining the core platform of the rDNA helix structure. Thus we introduce PIP2 as a novel component of the NOR complex, which is further engaged in the renewed rRNA synthesis upon exit from mitosis. PMID:24513678

RNA-Seq Alignment to Individualized Genomes Improves Transcript Abundance Estimates in Multiparent Populations

PubMed Central

Munger, Steven C.; Raghupathy, Narayanan; Choi, Kwangbom; Simons, Allen K.; Gatti, Daniel M.; Hinerfeld, Douglas A.; Svenson, Karen L.; Keller, Mark P.; Attie, Alan D.; Hibbs, Matthew A.; Graber, Joel H.; Chesler, Elissa J.; Churchill, Gary A.

2014-01-01

Massively parallel RNA sequencing (RNA-seq) has yielded a wealth of new insights into transcriptional regulation. A first step in the analysis of RNA-seq data is the alignment of short sequence reads to a common reference genome or transcriptome. Genetic variants that distinguish individual genomes from the reference sequence can cause reads to be misaligned, resulting in biased estimates of transcript abundance. Fine-tuning of read alignment algorithms does not correct this problem. We have developed Seqnature software to construct individualized diploid genomes and transcriptomes for multiparent populations and have implemented a complete analysis pipeline that incorporates other existing software tools. We demonstrate in simulated and real data sets that alignment to individualized transcriptomes increases read mapping accuracy, improves estimation of transcript abundance, and enables the direct estimation of allele-specific expression. Moreover, when applied to expression QTL mapping we find that our individualized alignment strategy corrects false-positive linkage signals and unmasks hidden associations. We recommend the use of individualized diploid genomes over reference sequence alignment for all applications of high-throughput sequencing technology in genetically diverse populations. PMID:25236449

Oligophrenin-1 (OPHN1), a Gene Involved in X-Linked Intellectual Disability, Undergoes RNA Editing and Alternative Splicing during Human Brain Development

PubMed Central

Athanasiadis, Alekos; Galeano, Federica; Locatelli, Franco; Bertini, Enrico; Zanni, Ginevra; Gallo, Angela

2014-01-01

Oligophrenin-1 (OPHN1) encodes for a Rho-GTPase-activating protein, important for dendritic morphogenesis and synaptic function. Mutations in this gene have been identified in patients with X-linked intellectual disability associated with cerebellar hypoplasia. ADAR enzymes are responsible for A-to-I RNA editing, an essential post-transcriptional RNA modification contributing to transcriptome and proteome diversification. Specifically, ADAR2 activity is essential for brain development and function. Herein, we show that the OPHN1 transcript undergoes post-transcriptional modifications such as A-to-I RNA editing and alternative splicing in human brain and other tissues. We found that OPHN1 editing is detectable already at the 18th week of gestation in human brain with a boost of editing at weeks 20 to 33, concomitantly with OPHN1 expression increase and the appearance of a novel OPHN1 splicing isoform. Our results demonstrate that multiple post-transcriptional events occur on OPHN1, a gene playing an important role in brain function and development. PMID:24637888

Oligophrenin-1 (OPHN1), a gene involved in X-linked intellectual disability, undergoes RNA editing and alternative splicing during human brain development.

PubMed

Barresi, Sabina; Tomaselli, Sara; Athanasiadis, Alekos; Galeano, Federica; Locatelli, Franco; Bertini, Enrico; Zanni, Ginevra; Gallo, Angela

2014-01-01

Oligophrenin-1 (OPHN1) encodes for a Rho-GTPase-activating protein, important for dendritic morphogenesis and synaptic function. Mutations in this gene have been identified in patients with X-linked intellectual disability associated with cerebellar hypoplasia. ADAR enzymes are responsible for A-to-I RNA editing, an essential post-transcriptional RNA modification contributing to transcriptome and proteome diversification. Specifically, ADAR2 activity is essential for brain development and function. Herein, we show that the OPHN1 transcript undergoes post-transcriptional modifications such as A-to-I RNA editing and alternative splicing in human brain and other tissues. We found that OPHN1 editing is detectable already at the 18th week of gestation in human brain with a boost of editing at weeks 20 to 33, concomitantly with OPHN1 expression increase and the appearance of a novel OPHN1 splicing isoform. Our results demonstrate that multiple post-transcriptional events occur on OPHN1, a gene playing an important role in brain function and development.

RAID: a comprehensive resource for human RNA-associated (RNA-RNA/RNA-protein) interaction.

PubMed

Zhang, Xiaomeng; Wu, Deng; Chen, Liqun; Li, Xiang; Yang, Jinxurong; Fan, Dandan; Dong, Tingting; Liu, Mingyue; Tan, Puwen; Xu, Jintian; Yi, Ying; Wang, Yuting; Zou, Hua; Hu, Yongfei; Fan, Kaili; Kang, Juanjuan; Huang, Yan; Miao, Zhengqiang; Bi, Miaoman; Jin, Nana; Li, Kongning; Li, Xia; Xu, Jianzhen; Wang, Dong

2014-07-01

Transcriptomic analyses have revealed an unexpected complexity in the eukaryote transcriptome, which includes not only protein-coding transcripts but also an expanding catalog of noncoding RNAs (ncRNAs). Diverse coding and noncoding RNAs (ncRNAs) perform functions through interaction with each other in various cellular processes. In this project, we have developed RAID (http://www.rna-society.org/raid), an RNA-associated (RNA-RNA/RNA-protein) interaction database. RAID intends to provide the scientific community with all-in-one resources for efficient browsing and extraction of the RNA-associated interactions in human. This version of RAID contains more than 6100 RNA-associated interactions obtained by manually reviewing more than 2100 published papers, including 4493 RNA-RNA interactions and 1619 RNA-protein interactions. Each entry contains detailed information on an RNA-associated interaction, including RAID ID, RNA/protein symbol, RNA/protein categories, validated method, expressing tissue, literature references (Pubmed IDs), and detailed functional description. Users can query, browse, analyze, and manipulate RNA-associated (RNA-RNA/RNA-protein) interaction. RAID provides a comprehensive resource of human RNA-associated (RNA-RNA/RNA-protein) interaction network. Furthermore, this resource will help in uncovering the generic organizing principles of cellular function network. © 2014 Zhang et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

Cell cycle-dependent transcription factors control the expression of yeast telomerase RNA.

PubMed

Dionne, Isabelle; Larose, Stéphanie; Dandjinou, Alain T; Abou Elela, Sherif; Wellinger, Raymund J

2013-07-01

Telomerase is a specialized ribonucleoprotein that adds repeated DNA sequences to the ends of eukaryotic chromosomes to preserve genome integrity. Some secondary structure features of the telomerase RNA are very well conserved, and it serves as a central scaffold for the binding of associated proteins. The Saccharomyces cerevisiae telomerase RNA, TLC1, is found in very low copy number in the cell and is the limiting component of the known telomerase holoenzyme constituents. The reasons for this low abundance are unclear, but given that the RNA is very stable, transcriptional control mechanisms must be extremely important. Here we define the sequences forming the TLC1 promoter and identify the elements required for its low expression level, including enhancer and repressor elements. Within an enhancer element, we found consensus sites for Mbp1/Swi4 association, and chromatin immunoprecipitation (ChIP) assays confirmed the binding of Mbp1 and Swi4 to these sites of the TLC1 promoter. Furthermore, the enhancer element conferred cell cycle-dependent regulation to a reporter gene, and mutations in the Mbp1/Swi4 binding sites affected the levels of telomerase RNA and telomere length. Finally, ChIP experiments using a TLC1 RNA-binding protein as target showed cell cycle-dependent transcription of the TLC1 gene. These results indicate that the budding yeast TLC1 RNA is transcribed in a cell cycle-dependent fashion late in G1 and may be part of the S phase-regulated group of genes involved in DNA replication.

The sequence, and its evolutionary implications, of a Thermococcus celer protein associated with transcription

NASA Technical Reports Server (NTRS)

Kaine, B. P.; Mehr, I. J.; Woese, C. R.

1994-01-01

Through random search, a gene from Thermococcus celer has been identified and sequenced that appears to encode a transcription-associated protein (110 amino acid residues). The sequence has clear homology to approximately the last half of an open reading frame reported previously for Sulfolobus acidocaldarius [Langer, D. & Zillig, W. (1993) Nucleic Acids Res. 21, 2251]. The protein translations of these two archaeal genes in turn are homologs of a small subunit found in eukaryotic RNA polymerase I (A12.2) and the counterpart of this from RNA polymerase II (B12.6). Homology is also seen with the eukaryotic transcription factor TFIIS, but it involves only the terminal 45 amino acids of the archaeal proteins. Evolutionary implications of these homologies are discussed.

MicroRNAs as Key Effectors in the p53 Network.

PubMed

Goeman, Frauke; Strano, Sabrina; Blandino, Giovanni

2017-01-01

The guardian of the genome p53 is embedded in a fine-spun network of MicroRNAs. p53 is able to activate or repress directly the transcription of MicroRNAs that are participating in the tumor-suppressive mission of p53. On the other hand, the expression of p53 is under tight control of MicroRNAs that are either targeting directly p53 or factors that are modifying its protein level or activity. Although the most important function of p53 is suggested to be transcriptional regulation, there are several nontranscriptional functions described. One of those regards the modulation of MicroRNA biogenesis. Wild-type p53 is increasing the maturation of selected MicroRNAs from the primary transcript to the precursor MiRNA by interacting with the Microprocessor complex. Furthermore, p53 is modulating the mRNA accessibility for certain MicroRNAs by association with the RISC complex and transcriptional regulation of RNA-binding proteins. In this way p53 is able to remodel the MiRNA-mRNA interaction network. As wild-type p53 is employing MicroRNAs to suppress cancer development, gain-of-function mutant p53 proteins use MicroRNAs to confer oncogenic properties like chemoresistance and the ability to drive metastasis. Like its wild-type counterpart mutant p53 is able to regulate MicroRNAs transcriptionally and posttranscriptionally. Mutant p53 affects the MiRNA processing at two cleavage steps through interfering with the Microprocessor complex and by downregulating Dicer and KSRP, a modulator of MiRNA biogenesis. Thus, MicroRNAs are essential components in the p53 pathway, contributing substantially to combat or enhance tumor development depending on the wild-type or mutant p53 context. © 2017 Elsevier Inc. All rights reserved.

Genome-wide association between DNA methylation and alternative splicing in an invertebrate

PubMed Central

2012-01-01

Background Gene bodies are the most evolutionarily conserved targets of DNA methylation in eukaryotes. However, the regulatory functions of gene body DNA methylation remain largely unknown. DNA methylation in insects appears to be primarily confined to exons. Two recent studies in Apis mellifera (honeybee) and Nasonia vitripennis (jewel wasp) analyzed transcription and DNA methylation data for one gene in each species to demonstrate that exon-specific DNA methylation may be associated with alternative splicing events. In this study we investigated the relationship between DNA methylation, alternative splicing, and cross-species gene conservation on a genome-wide scale using genome-wide transcription and DNA methylation data. Results We generated RNA deep sequencing data (RNA-seq) to measure genome-wide mRNA expression at the exon- and gene-level. We produced a de novo transcriptome from this RNA-seq data and computationally predicted splice variants for the honeybee genome. We found that exons that are included in transcription are higher methylated than exons that are skipped during transcription. We detected enrichment for alternative splicing among methylated genes compared to unmethylated genes using fisher’s exact test. We performed a statistical analysis to reveal that the presence of DNA methylation or alternative splicing are both factors associated with a longer gene length and a greater number of exons in genes. In concordance with this observation, a conservation analysis using BLAST revealed that each of these factors is also associated with higher cross-species gene conservation. Conclusions This study constitutes the first genome-wide analysis exhibiting a positive relationship between exon-level DNA methylation and mRNA expression in the honeybee. Our finding that methylated genes are enriched for alternative splicing suggests that, in invertebrates, exon-level DNA methylation may play a role in the construction of splice variants by positively influencing exon inclusion during transcription. The results from our cross-species homology analysis suggest that DNA methylation and alternative splicing are genetic mechanisms whose utilization could contribute to a longer gene length and a slower rate of gene evolution. PMID:22978521

Nuclear sequestration of COL1A1 mRNA transcript associated with type I osteogenesis imperfecta (OI)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Primorac, D.; Stover, M.L.; McKinstry, M.B.

Previously we identified an OI type I patient with a splice donor mutation that resulted in intron 26 retention instead of exon skipping and sequestration of normal levels of the mutant transcript in the nuclear compartment. Intron retention was consistent with the exon definition hypothesis for splice site selection since the size of the exon-intron-exon unit was less than 300 bp. Furthermore, the retained intron contained in-frame stop codons which is thought to cause the mutant RNA to remain within the nucleus rather than appearing in the cytoplasm. To test these hypotheses, genomic fragments containing the normal sequence or themore » donor mutation were cloned into a collagen minigene and expressed in stably tansfected NIH 3T3 cells. None of the modifications to the normal intron altered the level of RNA that accumulated in the cytoplasm, as expected. However none of the modifications to the mutant intron allowed accumulation of normal levels of mRNA in the cytoplasm. Moreover, in contrast to our findings in the patient`s cells only low levels of mutant transcript were found in the nucleus; a fraction of the transcript did appear in the cytoplasm which had spliced the mutant donor site correctly. Nuclear run-on experiments demonstrated equal levels of transcription from each transgene. Expression of another donor mutation known to cause in-frame exon skipping in OI type IV was accurately reproduced in the minigene in transfected 3T3 cells. Our experience suggests that either mechanism can lead to formation of a null allele possibly related to the type of splicing events surrounding the potential stop codons. Understanding the rules governing inactivation of a collagen RNA transcript may be important in designing a strategy to inactivate a dominate negative mutation associated with the more severe forms of OI.« less

Retrotransposon profiling of RNA polymerase III initiation sites.

PubMed

Qi, Xiaojie; Daily, Kenneth; Nguyen, Kim; Wang, Haoyi; Mayhew, David; Rigor, Paul; Forouzan, Sholeh; Johnston, Mark; Mitra, Robi David; Baldi, Pierre; Sandmeyer, Suzanne

2012-04-01

Although retroviruses are relatively promiscuous in choice of integration sites, retrotransposons can display marked integration specificity. In yeast and slime mold, some retrotransposons are associated with tRNA genes (tDNAs). In the Saccharomyces cerevisiae genome, the long terminal repeat retrotransposon Ty3 is found at RNA polymerase III (Pol III) transcription start sites of tDNAs. Ty1, 2, and 4 elements also cluster in the upstream regions of these genes. To determine the extent to which other Pol III-transcribed genes serve as genomic targets for Ty3, a set of 10,000 Ty3 genomic retrotranspositions were mapped using high-throughput DNA sequencing. Integrations occurred at all known tDNAs, two tDNA relics (iYGR033c and ZOD1), and six non-tDNA, Pol III-transcribed types of genes (RDN5, SNR6, SNR52, RPR1, RNA170, and SCR1). Previous work in vitro demonstrated that the Pol III transcription factor (TF) IIIB is important for Ty3 targeting. However, seven loci that bind the TFIIIB loader, TFIIIC, were not targeted, underscoring the unexplained absence of TFIIIB at those sites. Ty3 integrations also occurred in two open reading frames not previously associated with Pol III transcription, suggesting the existence of a small number of additional sites in the yeast genome that interact with Pol III transcription complexes.

Splicing Factor 2-Associated Protein p32 Participates in Ribosome Biogenesis by Regulating the Binding of Nop52 and Fibrillarin to Preribosome Particles*

PubMed Central

Yoshikawa, Harunori; Komatsu, Wataru; Hayano, Toshiya; Miura, Yutaka; Homma, Keiichi; Izumikawa, Keiichi; Ishikawa, Hideaki; Miyazawa, Naoki; Tachikawa, Hiroyuki; Yamauchi, Yoshio; Isobe, Toshiaki; Takahashi, Nobuhiro

2011-01-01

Ribosome biogenesis starts with transcription of the large ribosomal RNA precursor (47S pre-rRNA), which soon combines with numerous factors to form the 90S pre-ribosome in the nucleolus. Although the subsequent separation of the pre-90S particle into pre-40S and pre-60S particles is critical for the production process of mature small and large ribosomal subunits, its molecular mechanisms remain undetermined. Here, we present evidence that p32, fibrillarin (FBL), and Nop52 play key roles in this separation step. Mass-based analyses combined with immunoblotting showed that p32 associated with 155 proteins including 31 rRNA-processing factors (of which nine were components of small subunit processome, and six were those of RIX1 complex), 13 chromatin remodeling components, and six general transcription factors required for RNA polymerase III-mediated transcription. Of these, a late rRNA-processing factor Nop52 interacted directly with p32. Immunocytochemical analyses demonstrated that p32 colocalized with an early rRNA-processing factor FBL or Nop52 in the nucleolus and Cajal bodies, but was excluded from the nucleolus after actinomycin D treatment. p32 was present in the pre-ribosomal fractions prepared by cell fractionation or separated by ultracentrifugation of the nuclear extract. p32 also associated with pre-rRNAs including 47S/45S and 32S pre-rRNAs. Furthermore, knockdown of p32 with a small interfering RNA slowed the early processing from 47S/45S pre-rRNAs to 18S rRNA and 32S pre-rRNA. Finally, Nop52 was found to compete with FBL for binding to p32 probably in the nucleolus. Given the fact that FBL and Nop52 are associated with pre-ribosome particles distinctly different from each other, we suggest that p32 is a new rRNA maturation factor involved in the remodeling from pre-90S particles to pre-40S and pre-60S particles that requires the exchange of FBL for Nop52. PMID:21536856

Bijective transformation circular codes and nucleotide exchanging RNA transcription.

PubMed

Michel, Christian J; Seligmann, Hervé

2014-04-01

The C(3) self-complementary circular code X identified in genes of prokaryotes and eukaryotes is a set of 20 trinucleotides enabling reading frame retrieval and maintenance, i.e. a framing code (Arquès and Michel, 1996; Michel, 2012, 2013). Some mitochondrial RNAs correspond to DNA sequences when RNA transcription systematically exchanges between nucleotides (Seligmann, 2013a,b). We study here the 23 bijective transformation codes ΠX of X which may code nucleotide exchanging RNA transcription as suggested by this mitochondrial observation. The 23 bijective transformation codes ΠX are C(3) trinucleotide circular codes, seven of them are also self-complementary. Furthermore, several correlations are observed between the Reading Frame Retrieval (RFR) probability of bijective transformation codes ΠX and the different biological properties of ΠX related to their numbers of RNAs in GenBank's EST database, their polymerization rate, their number of amino acids and the chirality of amino acids they code. Results suggest that the circular code X with the functions of reading frame retrieval and maintenance in regular RNA transcription, may also have, through its bijective transformation codes ΠX, the same functions in nucleotide exchanging RNA transcription. Associations with properties such as amino acid chirality suggest that the RFR of X and its bijective transformations molded the origins of the genetic code's machinery. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Identification of proteins associated with the yeast mitochondrial RNA polymerase by tandem affinity purification

PubMed Central

Markov, Dmitriy A; Savkina, Maria; Anikin, Michael; Del Campo, Mark; Ecker, Karen; Lambowitz, Alan M; De Gnore, Jon P; McAllister, William T

2009-01-01

The abundance of mitochondrial (mt) transcripts varies under different conditions, and is thought to depend upon rates of transcription initiation, transcription termination/attenuation and RNA processing/degradation. The requirement to maintain the balance between RNA synthesis and processing may involve coordination between these processes; however, little is known about factors that regulate the activity of mtRNA polymerase (mtRNAP). Recent attempts to identify mtRNAP–protein interactions in yeast by means of a generalized tandem affinity purification (TAP) protocol were not successful, most likely because they involved a C-terminal mtRNAP–TAP fusion (which is incompatible with mtRNAP function) and because of the use of whole-cell solubilization protocols that did not preserve the integrity of mt protein complexes. Based upon the structure of T7 RNAP (to which mtRNAPs show high sequence similarity), we identified positions in yeast mtRNAP that allow insertion of a small affinity tag, confirmed the mature N-terminus, constructed a functional N-terminal TAP–mtRNAP fusion, pulled down associated proteins, and identified them by LC–MS–MS. Among the proteins found in the pull-down were a DEAD-box protein (Mss116p) and an RNA-binding protein (Pet127p). Previous genetic experiments suggested a role for these proteins in linking transcription and RNA degradation, in that a defect in the mt degradadosome could be suppressed by overexpression of either of these proteins or, independently, by mutations in either mtRNAP or its initiation factor Mtf1p. Further, we found that Mss116p inhibits transcription by mtRNAP in vitro in a steady-state reaction. Our results support the hypothesis that Mss116p and Pet127p are involved in modulation of mtRNAP activity. Copyright © 2009 John Wiley & Sons, Ltd. PMID:19536766

Integration of Multiple Genomic and Phenotype Data to Infer Novel miRNA-Disease Associations

PubMed Central

Zhou, Meng; Cheng, Liang; Yang, Haixiu; Wang, Jing; Sun, Jie; Wang, Zhenzhen

2016-01-01

MicroRNAs (miRNAs) play an important role in the development and progression of human diseases. The identification of disease-associated miRNAs will be helpful for understanding the molecular mechanisms of diseases at the post-transcriptional level. Based on different types of genomic data sources, computational methods for miRNA-disease association prediction have been proposed. However, individual source of genomic data tends to be incomplete and noisy; therefore, the integration of various types of genomic data for inferring reliable miRNA-disease associations is urgently needed. In this study, we present a computational framework, CHNmiRD, for identifying miRNA-disease associations by integrating multiple genomic and phenotype data, including protein-protein interaction data, gene ontology data, experimentally verified miRNA-target relationships, disease phenotype information and known miRNA-disease connections. The performance of CHNmiRD was evaluated by experimentally verified miRNA-disease associations, which achieved an area under the ROC curve (AUC) of 0.834 for 5-fold cross-validation. In particular, CHNmiRD displayed excellent performance for diseases without any known related miRNAs. The results of case studies for three human diseases (glioblastoma, myocardial infarction and type 1 diabetes) showed that all of the top 10 ranked miRNAs having no known associations with these three diseases in existing miRNA-disease databases were directly or indirectly confirmed by our latest literature mining. All these results demonstrated the reliability and efficiency of CHNmiRD, and it is anticipated that CHNmiRD will serve as a powerful bioinformatics method for mining novel disease-related miRNAs and providing a new perspective into molecular mechanisms underlying human diseases at the post-transcriptional level. CHNmiRD is freely available at http://www.bio-bigdata.com/CHNmiRD. PMID:26849207

Integration of Multiple Genomic and Phenotype Data to Infer Novel miRNA-Disease Associations.

PubMed

Shi, Hongbo; Zhang, Guangde; Zhou, Meng; Cheng, Liang; Yang, Haixiu; Wang, Jing; Sun, Jie; Wang, Zhenzhen

2016-01-01

MicroRNAs (miRNAs) play an important role in the development and progression of human diseases. The identification of disease-associated miRNAs will be helpful for understanding the molecular mechanisms of diseases at the post-transcriptional level. Based on different types of genomic data sources, computational methods for miRNA-disease association prediction have been proposed. However, individual source of genomic data tends to be incomplete and noisy; therefore, the integration of various types of genomic data for inferring reliable miRNA-disease associations is urgently needed. In this study, we present a computational framework, CHNmiRD, for identifying miRNA-disease associations by integrating multiple genomic and phenotype data, including protein-protein interaction data, gene ontology data, experimentally verified miRNA-target relationships, disease phenotype information and known miRNA-disease connections. The performance of CHNmiRD was evaluated by experimentally verified miRNA-disease associations, which achieved an area under the ROC curve (AUC) of 0.834 for 5-fold cross-validation. In particular, CHNmiRD displayed excellent performance for diseases without any known related miRNAs. The results of case studies for three human diseases (glioblastoma, myocardial infarction and type 1 diabetes) showed that all of the top 10 ranked miRNAs having no known associations with these three diseases in existing miRNA-disease databases were directly or indirectly confirmed by our latest literature mining. All these results demonstrated the reliability and efficiency of CHNmiRD, and it is anticipated that CHNmiRD will serve as a powerful bioinformatics method for mining novel disease-related miRNAs and providing a new perspective into molecular mechanisms underlying human diseases at the post-transcriptional level. CHNmiRD is freely available at http://www.bio-bigdata.com/CHNmiRD.

Aging in the Brain: New Roles of Epigenetics in Cognitive Decline.

PubMed

Barter, Jolie D; Foster, Thomas C

2018-06-01

Gene expression in the aging brain depends on transcription signals generated by senescent physiology, interacting with genetic and epigenetic programs. In turn, environmental factors influence epigenetic mechanisms, such that an epigenetic-environmental link may contribute to the accumulation of cellular damage, susceptibility or resilience to stressors, and variability in the trajectory of age-related cognitive decline. Epigenetic mechanisms, DNA methylation and histone modifications, alter chromatin structure and the accessibility of DNA. Furthermore, small non-coding RNA, termed microRNA (miRNA) bind to messenger RNA (mRNA) to regulate translation. In this review, we examine key questions concerning epigenetic mechanisms in regulating the expression of genes associated with brain aging and age-related cognitive decline. In addition, we highlight the interaction of epigenetics with senescent physiology and environmental factors in regulating transcription.

Long Noncoding RNA PANDA Positively Regulates Proliferation of Osteosarcoma Cells.

PubMed

Kotake, Yojiro; Goto, Taiki; Naemura, Madoka; Inoue, Yasutoshi; Okamoto, Haruna; Tahara, Keiichiro

2017-01-01

A long noncoding RNA, p21-associated ncRNA DNA damage-activated (PANDA), associates with nuclear transcription factor Y subunit alpha (NF-YA) and inhibits its binding to promoters of apoptosis-related genes, thereby repressing apoptosis in normal human fibroblasts. Here, we show that PANDA is involved in regulating proliferation in the U2OS human osteosarcoma cell line. U2OS cells were transfected with siRNAs against PANDA 72 h later and they were subjected to reverse transcription-polymerase chain reaction (RT-PCR), quantitative RT-PCR and cell-cycle analysis. PANDA was highly expressed in U2OS cells, and its expression was induced by DNA damage. Silencing PANDA caused arrest at the G 1 phase of the cell cycle, leading to inhibition of cell proliferation. Quantitative RT-PCR showed that silencing PANDA increased mRNA levels of the cyclin-dependent kinase inhibitor p18, which caused G 1 phase arrest. These results suggest that PANDA promotes G 1 -S transition by repressing p18 transcription, and thus promotes U2OS cell proliferation. Copyright© 2017 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

The transcriptome of Candida albicans mitochondria and the evolution of organellar transcription units in yeasts.

PubMed

Kolondra, Adam; Labedzka-Dmoch, Karolina; Wenda, Joanna M; Drzewicka, Katarzyna; Golik, Pawel

2015-10-21

Yeasts show remarkable variation in the organization of their mitochondrial genomes, yet there is little experimental data on organellar gene expression outside few model species. Candida albicans is interesting as a human pathogen, and as a representative of a clade that is distant from the model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. Unlike them, it encodes seven Complex I subunits in its mtDNA. No experimental data regarding organellar expression were available prior to this study. We used high-throughput RNA sequencing and traditional RNA biology techniques to study the mitochondrial transcriptome of C. albicans strains BWP17 and SN148. The 14 protein-coding genes, two ribosomal RNA genes, and 24 tRNA genes are expressed as eight primary polycistronic transcription units. We also found transcriptional activity in the noncoding regions, and antisense transcripts that could be a part of a regulatory mechanism. The promoter sequence is a variant of the nonanucleotide identified in other yeast mtDNAs, but some of the active promoters show significant departures from the consensus. The primary transcripts are processed by a tRNA punctuation mechanism into the monocistronic and bicistronic mature RNAs. The steady state levels of various mature transcripts exhibit large differences that are a result of posttranscriptional regulation. Transcriptome analysis allowed to precisely annotate the positions of introns in the RNL (2), COB (2) and COX1 (4) genes, as well as to refine the annotation of tRNAs and rRNAs. Comparative study of the mitochondrial genome organization in various Candida species indicates that they undergo shuffling in blocks usually containing 2-3 genes, and that their arrangement in primary transcripts is not conserved. tRNA genes with their associated promoters, as well as GC-rich sequence elements play an important role in these evolutionary events. The main evolutionary force shaping the mitochondrial genomes of yeasts is the frequent recombination, constantly breaking apart and joining genes into novel primary transcription units. The mitochondrial transcription units are constantly rearranged in evolution shaping the features of gene expression, such as the presence of secondary promoter sites that are inactive, or act as "booster" promoters, simplified transcriptional regulation and reliance on posttranscriptional mechanisms.

The lncRNA myocardial infarction associated transcript-centric competing endogenous RNA network in non-small-cell lung cancer.

PubMed

Zheng, Chang; Li, Xuelian; Qian, Biyun; Feng, Nannan; Gao, Sumeng; Zhao, Yuxia; Zhou, Baosen

2018-01-01

The leading cause of death for cancer is lung cancer, of which the majority subtype is non-small cell lung cancer (NSCLC). Recent studies have shown long non-coding RNAs are transcribed and contribute to cancer. Previous study has shown that a few single nucleotide polymorphisms (SNPs) in myocardial infarction associated transcript (MIAT) were associated with some diseases or function as competing endogenous RNA (ceRNA) in some cancer. We performed bioinformatic methods for analyzing RNA-seq and miRNA-seq data of NSCLC from The Cancer Genome Atlas database. 1352 NSCLC patients and 1320 cancer-free controls for genotyping, and dual luciferase reporter assay, real-time PCR are performed in A549 and H1975 lung cancer cell lines. Results are analyzed by SPSS v16.0. In the present study, we focus on the role of over-expression MIAT in NSCLC. We confirmed that rs1061451 T>C (allele odds ratio = 0.22; P < 0.01) was associated with NSCLC. Furthermore, we constructed MIAT-centric ceRNA network, and three mRNAs ( MYO1B , SGK1 and WNT9A ) was identified as targets by MIAT via miR-133a-5p. C-containing genotypes of MIAT rs1061451 were protective factor of NSCLC, and MIAT, which may act as ceRNA via miR-133a-5p, modulated MYO1B , SGK1 and WNT9A expression level.

The lncRNA myocardial infarction associated transcript-centric competing endogenous RNA network in non-small-cell lung cancer

PubMed Central

Zheng, Chang; Li, Xuelian; Qian, Biyun; Feng, Nannan; Gao, Sumeng; Zhao, Yuxia; Zhou, Baosen

2018-01-01

Background The leading cause of death for cancer is lung cancer, of which the majority subtype is non-small cell lung cancer (NSCLC). Recent studies have shown long non-coding RNAs are transcribed and contribute to cancer. Previous study has shown that a few single nucleotide polymorphisms (SNPs) in myocardial infarction associated transcript (MIAT) were associated with some diseases or function as competing endogenous RNA (ceRNA) in some cancer. Patients and methods We performed bioinformatic methods for analyzing RNA-seq and miRNA-seq data of NSCLC from The Cancer Genome Atlas database. 1352 NSCLC patients and 1320 cancer-free controls for genotyping, and dual luciferase reporter assay, real-time PCR are performed in A549 and H1975 lung cancer cell lines. Results are analyzed by SPSS v16.0. Results In the present study, we focus on the role of over-expression MIAT in NSCLC. We confirmed that rs1061451 T>C (allele odds ratio = 0.22; P < 0.01) was associated with NSCLC. Furthermore, we constructed MIAT-centric ceRNA network, and three mRNAs (MYO1B, SGK1 and WNT9A) was identified as targets by MIAT via miR-133a-5p. Conclusion C-containing genotypes of MIAT rs1061451 were protective factor of NSCLC, and MIAT, which may act as ceRNA via miR-133a-5p, modulated MYO1B, SGK1 and WNT9A expression level. PMID:29795987

Coupling mRNA processing with transcription in time and space

PubMed Central

Bentley, David L.

2015-01-01

Maturation of mRNA precursors often occurs simultaneously with their synthesis by RNA polymerase II (Pol II). The co-transcriptional nature of mRNA processing has permitted the evolution of coupling mechanisms that coordinate transcription with mRNA capping, splicing, editing and 3′ end formation. Recent experiments using sophisticated new methods for analysis of nascent RNA have provided important insights into the relative amount of co-transcriptional and post-transcriptional processing, the relationship between mRNA elongation and processing, and the role of the Pol II carboxy-terminal domain (CTD) in regulating these processes. PMID:24514444

Temporal and Spatial Post-Transcriptional Regulation of Zebrafish Tie1 mRNA by Long Noncoding RNA During Brain Vascular Assembly.

PubMed

Chowdhury, Tamjid A; Koceja, Chris; Eisa-Beygi, Shahram; Kleinstiver, Benjamin P; Kumar, Suresh N; Lin, Chien-Wei; Li, Keguo; Prabhudesai, Shubhangi; Joung, J Keith; Ramchandran, Ramani

2018-05-03

Tie1 (tyrosine kinase containing immunoglobulin and epidermal growth factor homology 1), an endothelial and hematopoietic cell-specific receptor tyrosine kinase, is an important regulator of angiogenesis and critical for maintaining vascular integrity. The post-transcriptional regulation of tie1 mRNA expression is not understood, but it might partly explain Tie1's differential expression pattern in endothelium. Following up on our previous work that identified natural antisense transcripts from the tie1 locus- tie1 antisense ( tie1AS ), which regulates tie1 mRNA levels in zebrafish-we attempted to identify the mechanism of this regulation. Through in vitro and in vivo ribonucleoprotein binding studies, we demonstrated that tie1AS long noncoding RNA interacts with an RNA binding protein-embryonic lethal and abnormal vision Drosophila-like 1 (Elavl1)-that regulates tie1 mRNA levels. When we disrupted the interaction between tie1AS and Elavl1 by using constitutively active antisense morpholino oligonucleotides or photoactivatable morpholino oligonucleotides, tie1 mRNA levels increased between 26 and 31 hours post-fertilization, particularly in the head. This increase correlated with dilation of primordial midbrain channels, smaller eyes, and reduced ventricular space. We also observed these phenotypes when we used CRISPR (clustered regularly interspaced short palindromic repeats)-mediated CRISPRi (CRISPR-mediated interference) to knock down tie1AS . Treatment of the morpholino oligonucleotide-injected embryos with a small molecule that decreased tie1 mRNA levels rescued all 3 abnormal phenotypes. We identified a novel mode of temporal and spatial post-transcriptional regulation of tie1 mRNA. It involves long noncoding RNA, tie1AS, and Elavl1 (an interactor of tie1AS ). © 2018 American Heart Association, Inc.

Identification of novel non-coding RNA-based negative feedback regulating the expression of the oncogenic transcription factor GLI1.

PubMed

Villegas, Victoria E; Rahman, Mohammed Ferdous-Ur; Fernandez-Barrena, Maite G; Diao, Yumei; Liapi, Eleni; Sonkoly, Enikö; Ståhle, Mona; Pivarcsi, Andor; Annaratone, Laura; Sapino, Anna; Ramírez Clavijo, Sandra; Bürglin, Thomas R; Shimokawa, Takashi; Ramachandran, Saraswathi; Kapranov, Philipp; Fernandez-Zapico, Martin E; Zaphiropoulos, Peter G

2014-07-01

Non-coding RNAs are a complex class of nucleic acids, with growing evidence supporting regulatory roles in gene expression. Here we identify a non-coding RNA located head-to-head with the gene encoding the Glioma-associated oncogene 1 (GLI1), a transcriptional effector of multiple cancer-associated signaling pathways. The expression of this three-exon GLI1 antisense (GLI1AS) RNA in cancer cells was concordant with GLI1 levels. siRNAs knockdown of GLI1AS up-regulated GLI1 and increased cellular proliferation and tumor growth in a xenograft model system. Conversely, GLI1AS overexpression decreased the levels of GLI1, its target genes PTCH1 and PTCH2, and cellular proliferation. Additionally, we demonstrate that GLI1 knockdown reduced GLI1AS, while GLI1 overexpression increased GLI1AS, supporting the role of GLI1AS as a target gene of the GLI1 transcription factor. Activation of TGFβ and Hedgehog signaling, two known regulators of GLI1 expression, conferred a concordant up-regulation of GLI1 and GLI1AS in cancer cells. Finally, analysis of the mechanism underlying the interplay between GLI1 and GLI1AS indicates that the non-coding RNA elicits a local alteration of chromatin structure by increasing the silencing mark H3K27me3 and decreasing the recruitment of RNA polymerase II to this locus. Taken together, the data demonstrate the existence of a novel non-coding RNA-based negative feedback loop controlling GLI1 levels, thus expanding the repertoire of mechanisms regulating the expression of this oncogenic transcription factor. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

The recruitment of the U5 snRNP to nascent transcripts requires internal loop 1 of U5 snRNA.

PubMed

Kim, Rebecca; Paschedag, Joshua; Novikova, Natalya; Bellini, Michel

2012-12-01

In this study, we take advantage of the high spatial resolution offered by the nucleus and lampbrush chromosomes of the amphibian oocyte to investigate the mechanisms that regulate the intranuclear trafficking of the U5 snRNP and its recruitment to nascent transcripts. We monitor the fate of newly assembled fluorescent U5 snRNP in Xenopus oocytes depleted of U4 and/or U6 snRNAs and demonstrate that the U4/U6.U5 tri-snRNP is not required for the association of U5 snRNP with Cajal bodies, splicing speckles, and nascent transcripts. In addition, using a mutational analysis, we show that a non-functional U5 snRNP can associate with nascent transcripts, and we further characterize internal loop structure 1 of U5 snRNA as a critical element for licensing U5 snRNP to target both nascent transcripts and splicing speckles. Collectively, our data support the model where the recruitment of snRNPs onto pre-mRNAs is independent of spliceosome assembly and suggest that U5 snRNP may promote the association of the U4/U6.U5 tri-snRNP with nascent transcripts.

SmD1 Modulates the miRNA Pathway Independently of Its Pre-mRNA Splicing Function.

PubMed

Xiong, Xiao-Peng; Vogler, Georg; Kurthkoti, Krishna; Samsonova, Anastasia; Zhou, Rui

2015-08-01

microRNAs (miRNAs) are a class of endogenous regulatory RNAs that play a key role in myriad biological processes. Upon transcription, primary miRNA transcripts are sequentially processed by Drosha and Dicer ribonucleases into ~22-24 nt miRNAs. Subsequently, miRNAs are incorporated into the RNA-induced silencing complexes (RISCs) that contain Argonaute (AGO) family proteins and guide RISC to target RNAs via complementary base pairing, leading to post-transcriptional gene silencing by a combination of translation inhibition and mRNA destabilization. Select pre-mRNA splicing factors have been implicated in small RNA-mediated gene silencing pathways in fission yeast, worms, flies and mammals, but the underlying molecular mechanisms are not well understood. Here, we show that SmD1, a core component of the Drosophila small nuclear ribonucleoprotein particle (snRNP) implicated in splicing, is required for miRNA biogenesis and function. SmD1 interacts with both the microprocessor component Pasha and pri-miRNAs, and is indispensable for optimal miRNA biogenesis. Depletion of SmD1 impairs the assembly and function of the miRISC without significantly affecting the expression of major canonical miRNA pathway components. Moreover, SmD1 physically and functionally associates with components of the miRISC, including AGO1 and GW182. Notably, miRNA defects resulting from SmD1 silencing can be uncoupled from defects in pre-mRNA splicing, and the miRNA and splicing machineries are physically and functionally distinct entities. Finally, photoactivatable-ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) analysis identifies numerous SmD1-binding events across the transcriptome and reveals direct SmD1-miRNA interactions. Our study suggests that SmD1 plays a direct role in miRNA-mediated gene silencing independently of its pre-mRNA splicing activity and indicates that the dual roles of splicing factors in post-transcriptional gene regulation may be evolutionarily widespread.

RAID: a comprehensive resource for human RNA-associated (RNA–RNA/RNA–protein) interaction

PubMed Central

Zhang, Xiaomeng; Wu, Deng; Chen, Liqun; Li, Xiang; Yang, Jinxurong; Fan, Dandan; Dong, Tingting; Liu, Mingyue; Tan, Puwen; Xu, Jintian; Yi, Ying; Wang, Yuting; Zou, Hua; Hu, Yongfei; Fan, Kaili; Kang, Juanjuan; Huang, Yan; Miao, Zhengqiang; Bi, Miaoman; Jin, Nana; Li, Kongning; Li, Xia; Xu, Jianzhen; Wang, Dong

2014-01-01

Transcriptomic analyses have revealed an unexpected complexity in the eukaryote transcriptome, which includes not only protein-coding transcripts but also an expanding catalog of noncoding RNAs (ncRNAs). Diverse coding and noncoding RNAs (ncRNAs) perform functions through interaction with each other in various cellular processes. In this project, we have developed RAID (http://www.rna-society.org/raid), an RNA-associated (RNA–RNA/RNA–protein) interaction database. RAID intends to provide the scientific community with all-in-one resources for efficient browsing and extraction of the RNA-associated interactions in human. This version of RAID contains more than 6100 RNA-associated interactions obtained by manually reviewing more than 2100 published papers, including 4493 RNA–RNA interactions and 1619 RNA–protein interactions. Each entry contains detailed information on an RNA-associated interaction, including RAID ID, RNA/protein symbol, RNA/protein categories, validated method, expressing tissue, literature references (Pubmed IDs), and detailed functional description. Users can query, browse, analyze, and manipulate RNA-associated (RNA–RNA/RNA–protein) interaction. RAID provides a comprehensive resource of human RNA-associated (RNA–RNA/RNA–protein) interaction network. Furthermore, this resource will help in uncovering the generic organizing principles of cellular function network. PMID:24803509

Synthesis of photolabile transcription initiators and preparation of photocleavable functional RNA by transcription.

PubMed

Huang, Faqing; Shi, Yongliang

2012-07-01

Two new photolabile adenosine-containing transcription initiators with terminal thiol and amino functionalities are chemically synthesized. Transcription in the presence of the transcription initiators under the T7 phi2.5 promoter produces 5' thiol- and amino-functionalized RNA conjugated by a photocleavable (PC) linker. Further RNA functionalization with biotin may be achieved through acyl transfer reactions from either biotinyl AMP to the RNA thiol group or biotin NHS to the RNA amino group. Photocleavage of the PC linker displays relatively fast kinetics with a half-life of 4-5 min. The availability of these transcription initiators makes new photolabile RNA accessible for affinity purification of RNA, in vitro selection of functional RNAs, and functional RNA caging. Copyright © 2012 Elsevier Ltd. All rights reserved.

Polycomb repressive complex 1 modifies transcription of active genes

PubMed Central

Pherson, Michelle; Misulovin, Ziva; Gause, Maria; Mihindukulasuriya, Kathie; Swain, Amanda; Dorsett, Dale

2017-01-01

This study examines the role of Polycomb repressive complex 1 (PRC1) at active genes. The PRC1 and PRC2 complexes are crucial for epigenetic silencing during development of an organism. They are recruited to Polycomb response elements (PREs) and establish silenced domains over several kilobases. Recent studies show that PRC1 is also directly recruited to active genes by the cohesin complex. Cohesin participates broadly in control of gene transcription, but it is unknown whether cohesin-recruited PRC1 also plays a role in transcriptional control of active genes. We address this question using genome-wide RNA sequencing (RNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq). The results show that PRC1 influences transcription of active genes, and a significant fraction of its effects are likely direct. The roles of different PRC1 subunits can also vary depending on the gene. Depletion of PRC1 subunits by RNA interference alters phosphorylation of RNA polymerase II (Pol II) and occupancy by the Spt5 pausing-elongation factor at most active genes. These effects on Pol II phosphorylation and Spt5 are likely linked to changes in elongation and RNA processing detected by nascent RNA-seq, although the mechanisms remain unresolved. The experiments also reveal that PRC1 facilitates association of Spt5 with enhancers and PREs. Reduced Spt5 levels at these regulatory sequences upon PRC1 depletion coincide with changes in Pol II occupancy and phosphorylation. Our findings indicate that, in addition to its repressive roles in epigenetic gene silencing, PRC1 broadly influences transcription of active genes and may suppress transcription of nonpromoter regulatory sequences. PMID:28782042

NMD3 regulates both mRNA and rRNA nuclear export in African trypanosomes via an XPOI-linked pathway

PubMed Central

Bühlmann, Melanie; Walrad, Pegine; Rico, Eva; Ivens, Alasdair; Capewell, Paul; Naguleswaran, Arunasalam; Roditi, Isabel; Matthews, Keith R.

2015-01-01

Trypanosomes mostly regulate gene expression through post-transcriptional mechanisms, particularly mRNA stability. However, much mRNA degradation is cytoplasmic such that mRNA nuclear export must represent an important level of regulation. Ribosomal RNAs must also be exported from the nucleus and the trypanosome orthologue of NMD3 has been confirmed to be involved in rRNA processing and export, matching its function in other organisms. Surprisingly, we found that TbNMD3 depletion also generates mRNA accumulation of procyclin-associated genes (PAGs), these being co-transcribed by RNA polymerase I with the procyclin surface antigen genes expressed on trypanosome insect forms. By whole transcriptome RNA-seq analysis of TbNMD3-depleted cells we confirm the regulation of the PAG transcripts by TbNMD3 and using reporter constructs reveal that PAG1 regulation is mediated by its 5′UTR. Dissection of the mechanism of regulation demonstrates that it is not dependent upon translational inhibition mediated by TbNMD3 depletion nor enhanced transcription. However, depletion of the nuclear export factors XPO1 or MEX67 recapitulates the effects of TbNMD3 depletion on PAG mRNAs and mRNAs accumulated in the nucleus of TbNMD3-depleted cells. These results invoke a novel RNA regulatory mechanism involving the NMD3-dependent nuclear export of mRNA cargos, suggesting a shared platform for mRNA and rRNA export. PMID:25873624

IntNetLncSim: an integrative network analysis method to infer human lncRNA functional similarity

PubMed Central

Hu, Yang; Yang, Haixiu; Zhou, Chen; Sun, Jie; Zhou, Meng

2016-01-01

Increasing evidence indicated that long non-coding RNAs (lncRNAs) were involved in various biological processes and complex diseases by communicating with mRNAs/miRNAs each other. Exploiting interactions between lncRNAs and mRNA/miRNAs to lncRNA functional similarity (LFS) is an effective method to explore function of lncRNAs and predict novel lncRNA-disease associations. In this article, we proposed an integrative framework, IntNetLncSim, to infer LFS by modeling the information flow in an integrated network that comprises both lncRNA-related transcriptional and post-transcriptional information. The performance of IntNetLncSim was evaluated by investigating the relationship of LFS with the similarity of lncRNA-related mRNA sets (LmRSets) and miRNA sets (LmiRSets). As a result, LFS by IntNetLncSim was significant positively correlated with the LmRSet (Pearson correlation γ2=0.8424) and LmiRSet (Pearson correlation γ2=0.2601). Particularly, the performance of IntNetLncSim is superior to several previous methods. In the case of applying the LFS to identify novel lncRNA-disease relationships, we achieved an area under the ROC curve (0.7300) in experimentally verified lncRNA-disease associations based on leave-one-out cross-validation. Furthermore, highly-ranked lncRNA-disease associations confirmed by literature mining demonstrated the excellent performance of IntNetLncSim. Finally, a web-accessible system was provided for querying LFS and potential lncRNA-disease relationships: http://www.bio-bigdata.com/IntNetLncSim. PMID:27323856

IntNetLncSim: an integrative network analysis method to infer human lncRNA functional similarity.

PubMed

Cheng, Liang; Shi, Hongbo; Wang, Zhenzhen; Hu, Yang; Yang, Haixiu; Zhou, Chen; Sun, Jie; Zhou, Meng

2016-07-26

Increasing evidence indicated that long non-coding RNAs (lncRNAs) were involved in various biological processes and complex diseases by communicating with mRNAs/miRNAs each other. Exploiting interactions between lncRNAs and mRNA/miRNAs to lncRNA functional similarity (LFS) is an effective method to explore function of lncRNAs and predict novel lncRNA-disease associations. In this article, we proposed an integrative framework, IntNetLncSim, to infer LFS by modeling the information flow in an integrated network that comprises both lncRNA-related transcriptional and post-transcriptional information. The performance of IntNetLncSim was evaluated by investigating the relationship of LFS with the similarity of lncRNA-related mRNA sets (LmRSets) and miRNA sets (LmiRSets). As a result, LFS by IntNetLncSim was significant positively correlated with the LmRSet (Pearson correlation γ2=0.8424) and LmiRSet (Pearson correlation γ2=0.2601). Particularly, the performance of IntNetLncSim is superior to several previous methods. In the case of applying the LFS to identify novel lncRNA-disease relationships, we achieved an area under the ROC curve (0.7300) in experimentally verified lncRNA-disease associations based on leave-one-out cross-validation. Furthermore, highly-ranked lncRNA-disease associations confirmed by literature mining demonstrated the excellent performance of IntNetLncSim. Finally, a web-accessible system was provided for querying LFS and potential lncRNA-disease relationships: http://www.bio-bigdata.com/IntNetLncSim.

The context of transcription start site regions is crucial for transcription of a plant tRNA(Lys)(UUU) gene group both in vitro and in vivo.

PubMed

Yukawa, Yasushi; Akama, Kazuhito; Noguchi, Kanta; Komiya, Masaaki; Sugiura, Masahiro

2013-01-10

Nuclear tRNA genes are transcribed by RNA polymerase III. The A- and B-boxes located within the transcribed regions are essential promoter elements for nuclear tRNA gene transcription. The Arabidopsis genome contains ten annotated genes encoding identical tRNA(Lys)(UUU) molecules, which are scattered on the five chromosomes. In this study, we prepared ten tDNA constructs including each of the tRNA(Lys)(UUU) coding sequences with their individual 5' and 3' flanking sequences, and assayed tRNA expression using an in vitro RNA polymerase III-dependent transcription system. Transcription levels differed significantly among the ten genes and two of the tRNA genes were transcribed at a very low level, despite possessing A- and B-boxes identical to those of the other tRNA genes. To examine whether the in vitro results were reproducible in vivo, the 5' flanking sequence of an amber suppressor tRNA gene was then replaced with those of the ten tRNA(Lys) genes. An in vivo experiment based on an amber suppressor tRNA that mediates suppression of a premature amber codon in a β-glucuronidase (GUS) reporter gene in plant tissues generated nearly identical results to those obtained in vitro. Analysis of mutated versions of the amber suppressor tRNA gene, which contained base substitutions around the transcription start site (TSS), showed that the context around the transcription start sites is a crucial determinant for transcription of plant tRNA(Lys)(UUU) both in vitro and in vivo. The above transcription regulation by context around TSS differed between tRNA genes and other Pol III-dependent genes. Copyright © 2012 Elsevier B.V. All rights reserved.

Mutational analysis reveals a noncontractile but interactive role of actin and profilin in viral RNA-dependent RNA synthesis.

PubMed

Harpen, Mary; Barik, Tiasha; Musiyenko, Alla; Barik, Sailen

2009-11-01

As obligatory parasites, viruses co-opt a variety of cellular functions for robust replication. The expression of the nonsegmented negative-strand RNA genome of respiratory syncytial virus (RSV), a significant pediatric pathogen, absolutely requires actin and is stimulated by the actin-regulatory protein profilin. As actin is a major contractile protein, it was important to determine whether the known functional domains of actin and profilin were important for their ability to activate RSV transcription. Analyses of recombinant mutants in a reconstituted RSV transcription system suggested that the divalent-cation-binding domain of actin is critically needed for binding to the RSV genome template and for the activation of viral RNA synthesis. In contrast, the nucleotide-binding domain and the N-terminal acidic domain were needed neither for template binding nor for transcription. Specific surface residues of actin, required for actin-actin contact during filamentation, were also nonessential for viral transcription. Unlike actin, profilin did not directly bind to the viral template but was recruited by actin. Mutation of the interactive residues of actin or profilin, resulting in the loss of actin-profilin binding, also abolished profilin's ability to stimulate viral transcription. Together, these results suggest that actin acts as a classical transcription factor for the virus by divalent-cation-dependent binding to the viral template and that profilin acts as a transcriptional cofactor, in part by associating with actin. This essential viral role of actin is independent of its contractile cellular role.

On the Minimization of Fluctuations in the Response Times of Autoregulatory Gene Networks

PubMed Central

Murugan, Rajamanickam; Kreiman, Gabriel

2011-01-01

The temporal dynamics of the concentrations of several proteins are tightly regulated, particularly for critical nodes in biological networks such as transcription factors. An important mechanism to control transcription factor levels is through autoregulatory feedback loops where the protein can bind its own promoter. Here we use theoretical tools and computational simulations to further our understanding of transcription-factor autoregulatory loops. We show that the stochastic dynamics of feedback and mRNA synthesis can significantly influence the speed of response of autoregulatory genetic networks toward external stimuli. The fluctuations in the response-times associated with the accumulation of the transcription factor in the presence of negative or positive autoregulation can be minimized by confining the ratio of mRNA/protein lifetimes within 1:10. This predicted range of mRNA/protein lifetime agrees with ranges observed empirically in prokaryotes and eukaryotes. The theory can quantitatively and systematically account for the influence of regulatory element binding and unbinding dynamics on the transcription-factor concentration rise-times. The simulation results are robust against changes in several system parameters of the gene expression machinery. PMID:21943410

c-Jun binds the N terminus of human TAF(II)250 to derepress RNA polymerase II transcription in vitro.

PubMed

Lively, T N; Ferguson, H A; Galasinski, S K; Seto, A G; Goodrich, J A

2001-07-06

c-Jun is an oncoprotein that activates transcription of many genes involved in cell growth and proliferation. We studied the mechanism of transcriptional activation by human c-Jun in a human RNA polymerase II transcription system composed of highly purified recombinant and native transcription factors. Transcriptional activation by c-Jun depends on the TATA-binding protein (TBP)-associated factor (TAF) subunits of transcription factor IID (TFIID). Protein-protein interaction assays revealed that c-Jun binds with high specificity to the largest subunit of human TFIID, TAF(II)250. The region of TAF(II)250 bound by c-Jun lies in the N-terminal 163 amino acids. This same region of TAF(II)250 binds to TBP and represses its interaction with TATA boxes, thereby decreasing DNA binding by TFIID. We hypothesized that c-Jun is capable of derepressing the effect of the TAF(II)250 N terminus on TFIID-driven transcription. In support of this hypothesis, we found that c-Jun increased levels of TFIID-driven transcription in vitro when added at high concentrations to a DNA template lacking activator protein 1 (AP-1) sites. Moreover, c-Jun blocked the repression of TBP DNA binding caused by the N terminus of TAF(II)250. In addition to revealing a mechanism by which c-Jun activates transcription, our studies provide the first evidence that an activator can bind directly to the N terminus of TAF(II)250 to derepress RNA polymerase II transcription in vitro.

Methylation pattern of IFNG in periapical granulomas and radicular cysts.

PubMed

Campos, Kelma; Gomes, Carolina Cavaliéri; de Fátima Correia-Silva, Jeane; Farias, Lucyana Conceição; Fonseca-Silva, Thiago; Bernardes, Vanessa Fátima; Pereira, Cláudia Maria; Gomez, Ricardo Santiago

2013-04-01

Interferon-γ plays an important role in the pathogenesis of periapical lesions, and the methylation of IFNG has been associated with transcriptional inactivation. The purpose of the present study was to investigate IFNG promoter methylation in association with gene transcription and protein levels in periapical granulomas and radicular cysts. Methylation-specific polymerase chain reaction was used to assess the DNA methylation pattern of the IFNG gene in 16 periapical granulomas and 13 radicular cyst samples. The transcription levels of IFNG mRNA were verified by quantitative real-time polymerase chain reaction, and protein expression was evaluated by immunohistochemistry. All the periapical lesion samples exhibited partial or total methylation of the IFNG gene. In addition, an increased methylation profile was found in radicular cysts compared with periapical granulomas. Increased IFNG mRNA expression was observed in the partially methylated periapical lesion samples relative to the samples that were completely methylated. The present study provides the first evidence of the possible impact of IFNG methylation on IFNG transcription in periapical lesions. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Identification of MicroRNAs and their Targets Associated with Embryo Abortion during Chrysanthemum Cross Breeding via High-Throughput Sequencing.

PubMed

Zhang, Fengjiao; Dong, Wen; Huang, Lulu; Song, Aiping; Wang, Haibin; Fang, Weimin; Chen, Fadi; Teng, Nianjun

2015-01-01

MicroRNAs (miRNAs) are important regulators in plant development. They post-transcriptionally regulate gene expression during various biological and metabolic processes by binding to the 3'-untranslated region of target mRNAs to facilitate mRNA degradation or inhibit translation. Chrysanthemum (Chrysanthemum morifolium) is one of the most important ornamental flowers with increasing demand each year. However, embryo abortion is the main reason for chrysanthemum cross breeding failure. To date, there have been no experiments examining the expression of miRNAs associated with chrysanthemum embryo development. Therefore, we sequenced three small RNA libraries to identify miRNAs and their functions. Our results will provide molecular insights into chrysanthemum embryo abortion. Three small RNA libraries were built from normal chrysanthemum ovules at 12 days after pollination (DAP), and normal and abnormal chrysanthemum ovules at 18 DAP. We validated 228 miRNAs with significant changes in expression frequency during embryonic development. Comparative profiling revealed that 69 miRNAs exhibited significant differential expression between normal and abnormal embryos at 18 DAP. In addition, a total of 1037 miRNA target genes were predicted, and their annotations were defined by transcriptome data. Target genes associated with metabolic pathways were most highly represented according to the annotation. Moreover, 52 predicted target genes were identified to be associated with embryonic development, including 31 transcription factors and 21 additional genes. Gene ontology (GO) annotation also revealed that high-ranking miRNA target genes related to cellular processes and metabolic processes were involved in transcription regulation and the embryo developmental process. The present study generated three miRNA libraries and gained information on miRNAs and their targets in the chrysanthemum embryo. These results enrich the growing database of new miRNAs and lay the foundation for the further understanding of miRNA biological function in the regulation of chrysanthemum embryo abortion.

Comparative analysis of response to selection with three insecticides in the dengue mosquito Aedes aegypti using mRNA sequencing

PubMed Central

2014-01-01

Background Mosquito control programmes using chemical insecticides are increasingly threatened by the development of resistance. Such resistance can be the consequence of changes in proteins targeted by insecticides (target site mediated resistance), increased insecticide biodegradation (metabolic resistance), altered transport, sequestration or other mechanisms. As opposed to target site resistance, other mechanisms are far from being fully understood. Indeed, insecticide selection often affects a large number of genes and various biological processes can hypothetically confer resistance. In this context, the aim of the present study was to use RNA sequencing (RNA-seq) for comparing transcription level and polymorphism variations associated with adaptation to chemical insecticides in the mosquito Aedes aegypti. Biological materials consisted of a parental susceptible strain together with three child strains selected across multiple generations with three insecticides from different classes: the pyrethroid permethrin, the neonicotinoid imidacloprid and the carbamate propoxur. Results After ten generations, insecticide-selected strains showed elevated resistance levels to the insecticides used for selection. RNA-seq data allowed detecting over 13,000 transcripts, of which 413 were differentially transcribed in insecticide-selected strains as compared to the susceptible strain. Among them, a significant enrichment of transcripts encoding cuticle proteins, transporters and enzymes was observed. Polymorphism analysis revealed over 2500 SNPs showing > 50% allele frequency variations in insecticide-selected strains as compared to the susceptible strain, affecting over 1000 transcripts. Comparing gene transcription and polymorphism patterns revealed marked differences among strains. While imidacloprid selection was linked to the over transcription of many genes, permethrin selection was rather linked to polymorphism variations. Focusing on detoxification enzymes revealed that permethrin selection strongly affected the polymorphism of several transcripts encoding cytochrome P450 monooxygenases likely involved in insecticide biodegradation. Conclusions The present study confirmed the power of RNA-seq for identifying concomitantly quantitative and qualitative transcriptome changes associated with insecticide resistance in mosquitoes. Our results suggest that transcriptome modifications can be selected rapidly by insecticides and affect multiple biological functions. Previously neglected by molecular screenings, polymorphism variations of detoxification enzymes may play an important role in the adaptive response of mosquitoes to insecticides. PMID:24593293

Comparative analysis of response to selection with three insecticides in the dengue mosquito Aedes aegypti using mRNA sequencing.

PubMed

David, Jean-Philippe; Faucon, Frédéric; Chandor-Proust, Alexia; Poupardin, Rodolphe; Riaz, Muhammad Asam; Bonin, Aurélie; Navratil, Vincent; Reynaud, Stéphane

2014-03-05

Mosquito control programmes using chemical insecticides are increasingly threatened by the development of resistance. Such resistance can be the consequence of changes in proteins targeted by insecticides (target site mediated resistance), increased insecticide biodegradation (metabolic resistance), altered transport, sequestration or other mechanisms. As opposed to target site resistance, other mechanisms are far from being fully understood. Indeed, insecticide selection often affects a large number of genes and various biological processes can hypothetically confer resistance. In this context, the aim of the present study was to use RNA sequencing (RNA-seq) for comparing transcription level and polymorphism variations associated with adaptation to chemical insecticides in the mosquito Aedes aegypti. Biological materials consisted of a parental susceptible strain together with three child strains selected across multiple generations with three insecticides from different classes: the pyrethroid permethrin, the neonicotinoid imidacloprid and the carbamate propoxur. After ten generations, insecticide-selected strains showed elevated resistance levels to the insecticides used for selection. RNA-seq data allowed detecting over 13,000 transcripts, of which 413 were differentially transcribed in insecticide-selected strains as compared to the susceptible strain. Among them, a significant enrichment of transcripts encoding cuticle proteins, transporters and enzymes was observed. Polymorphism analysis revealed over 2500 SNPs showing > 50% allele frequency variations in insecticide-selected strains as compared to the susceptible strain, affecting over 1000 transcripts. Comparing gene transcription and polymorphism patterns revealed marked differences among strains. While imidacloprid selection was linked to the over transcription of many genes, permethrin selection was rather linked to polymorphism variations. Focusing on detoxification enzymes revealed that permethrin selection strongly affected the polymorphism of several transcripts encoding cytochrome P450 monooxygenases likely involved in insecticide biodegradation. The present study confirmed the power of RNA-seq for identifying concomitantly quantitative and qualitative transcriptome changes associated with insecticide resistance in mosquitoes. Our results suggest that transcriptome modifications can be selected rapidly by insecticides and affect multiple biological functions. Previously neglected by molecular screenings, polymorphism variations of detoxification enzymes may play an important role in the adaptive response of mosquitoes to insecticides.

Mechanisms employed by retroviruses to exploit host factors for translational control of a complicated proteome

PubMed Central

Bolinger, Cheryl; Boris-Lawrie, Kathleen

2009-01-01

Retroviruses have evolved multiple strategies to direct the synthesis of a complex proteome from a single primary transcript. Their mechanisms are modulated by a breadth of virus-host interactions, which are of significant fundamental interest because they ultimately affect the efficiency of virus replication and disease pathogenesis. Motifs located within the untranslated region (UTR) of the retroviral RNA have established roles in transcriptional trans-activation, RNA packaging, and genome reverse transcription; and a growing literature has revealed a necessary role of the UTR in modulating the efficiency of viral protein synthesis. Examples include a 5' UTR post-transcriptional control element (PCE), present in at least eight retroviruses, that interacts with cellular RNA helicase A to facilitate cap-dependent polyribosome association; and 3' UTR constitutive transport element (CTE) of Mason-Pfizer monkey virus that interacts with Tap/NXF1 and SR protein 9G8 to facilitate RNA export and translational utilization. By contrast, nuclear protein hnRNP E1 negatively modulates HIV-1 Gag, Env, and Rev protein synthesis. Alternative initiation strategies by ribosomal frameshifting and leaky scanning enable polycistronic translation of the cap-dependent viral transcript. Other studies posit cap-independent translation initiation by internal ribosome entry at structural features of the 5' UTR of selected retroviruses. The retroviral armamentarium also commands mechanisms to counter cellular post-transcriptional innate defenses, including protein kinase R, 2',5'-oligoadenylate synthetase and the small RNA pathway. This review will discuss recent and historically-recognized insights into retrovirus translational control. The expanding knowledge of retroviral post-transcriptional control is vital to understanding the biology of the retroviral proteome. In a broad perspective, each new insight offers a prospective target for antiviral therapy and strategic improvement of gene transfer vectors. PMID:19166625

Analysis of Single-cell Gene Transcription by RNA Fluorescent In Situ Hybridization (FISH)

PubMed Central

Ronander, Elena; Bengtsson, Dominique C.; Joergensen, Louise; Jensen, Anja T. R.; Arnot, David E.

2012-01-01

Adhesion of Plasmodium falciparum infected erythrocytes (IE) to human endothelial receptors during malaria infections is mediated by expression of PfEMP1 protein variants encoded by the var genes. The haploid P. falciparum genome harbors approximately 60 different var genes of which only one has been believed to be transcribed per cell at a time during the blood stage of the infection. How such mutually exclusive regulation of var gene transcription is achieved is unclear, as is the identification of individual var genes or sub-groups of var genes associated with different receptors and the consequence of differential binding on the clinical outcome of P. falciparum infections. Recently, the mutually exclusive transcription paradigm has been called into doubt by transcription assays based on individual P. falciparum transcript identification in single infected erythrocytic cells using RNA fluorescent in situ hybridization (FISH) analysis of var gene transcription by the parasite in individual nuclei of P. falciparum IE1. Here, we present a detailed protocol for carrying out the RNA-FISH methodology for analysis of var gene transcription in single-nuclei of P. falciparum infected human erythrocytes. The method is based on the use of digoxigenin- and biotin- labeled antisense RNA probes using the TSA Plus Fluorescence Palette System2 (Perkin Elmer), microscopic analyses and freshly selected P. falciparum IE. The in situ hybridization method can be used to monitor transcription and regulation of a variety of genes expressed during the different stages of the P. falciparum life cycle and is adaptable to other malaria parasite species and other organisms and cell types. PMID:23070076

Positive feedback between RNA-binding protein HuD and transcription factor SATB1 promotes neurogenesis.

PubMed

Wang, Feifei; Tidei, Joseph J; Polich, Eric D; Gao, Yu; Zhao, Huashan; Perrone-Bizzozero, Nora I; Guo, Weixiang; Zhao, Xinyu

2015-09-08

The mammalian embryonic lethal abnormal vision (ELAV)-like protein HuD is a neuronal RNA-binding protein implicated in neuronal development, plasticity, and diseases. Although HuD has long been associated with neuronal development, the functions of HuD in neural stem cell differentiation and the underlying mechanisms have gone largely unexplored. Here we show that HuD promotes neuronal differentiation of neural stem/progenitor cells (NSCs) in the adult subventricular zone by stabilizing the mRNA of special adenine-thymine (AT)-rich DNA-binding protein 1 (SATB1), a critical transcriptional regulator in neurodevelopment. We find that SATB1 deficiency impairs the neuronal differentiation of NSCs, whereas SATB1 overexpression rescues the neuronal differentiation phenotypes resulting from HuD deficiency. Interestingly, we also discover that SATB1 is a transcriptional activator of HuD during NSC neuronal differentiation. In addition, we demonstrate that NeuroD1, a neuronal master regulator, is a direct downstream target of SATB1. Therefore, HuD and SATB1 form a positive regulatory loop that enhances NeuroD1 transcription and subsequent neuronal differentiation. Our results here reveal a novel positive feedback network between an RNA-binding protein and a transcription factor that plays critical regulatory roles in neurogenesis.

Promoter Targeting RNAs: Unexpected Contributors to the Control of HIV-1 Transcription.

PubMed

Suzuki, Kazuo; Ahlenstiel, Chantelle; Marks, Katherine; Kelleher, Anthony D

2015-01-27

In spite of prolonged and intensive treatment with combined antiretroviral therapy (cART), which efficiently suppresses plasma viremia, the integrated provirus of HIV-1 persists in resting memory CD4(+) T cells as latent infection. Treatment with cART does not substantially reduce the burden of latent infection. Once cART is ceased, HIV-1 replication recrudesces from these reservoirs in the overwhelming majority of patients. There is increasing evidence supporting a role for noncoding RNAs (ncRNA), including microRNAs (miRNAs), antisense (as)RNAs, and short interfering (si)RNA in the regulation of HIV-1 transcription. This appears to be mediated by interaction with the HIV-1 promoter region. Viral miRNAs have the potential to act as positive or negative regulators of HIV transcription. Moreover, inhibition of virally encoded long-asRNA can induce positive transcriptional regulation, while antisense strands of siRNA targeting the NF-κB region suppress viral transcription. An in-depth understanding of the interaction between ncRNAs and the HIV-1 U3 promoter region may lead to new approaches for the control of HIV reservoirs. This review focuses on promoter associated ncRNAs, with particular emphasis on their role in determining whether HIV-1 establishes active or latent infection.

Promoter Targeting RNAs: Unexpected Contributors to the Control of HIV-1 Transcription

PubMed Central

Suzuki, Kazuo; Ahlenstiel, Chantelle; Marks, Katherine; Kelleher, Anthony D

2015-01-01

In spite of prolonged and intensive treatment with combined antiretroviral therapy (cART), which efficiently suppresses plasma viremia, the integrated provirus of HIV-1 persists in resting memory CD4+ T cells as latent infection. Treatment with cART does not substantially reduce the burden of latent infection. Once cART is ceased, HIV-1 replication recrudesces from these reservoirs in the overwhelming majority of patients. There is increasing evidence supporting a role for noncoding RNAs (ncRNA), including microRNAs (miRNAs), antisense (as)RNAs, and short interfering (si)RNA in the regulation of HIV-1 transcription. This appears to be mediated by interaction with the HIV-1 promoter region. Viral miRNAs have the potential to act as positive or negative regulators of HIV transcription. Moreover, inhibition of virally encoded long-asRNA can induce positive transcriptional regulation, while antisense strands of siRNA targeting the NF-κB region suppress viral transcription. An in-depth understanding of the interaction between ncRNAs and the HIV-1 U3 promoter region may lead to new approaches for the control of HIV reservoirs. This review focuses on promoter associated ncRNAs, with particular emphasis on their role in determining whether HIV-1 establishes active or latent infection. PMID:25625613

MAGIA2: from miRNA and genes expression data integrative analysis to microRNA–transcription factor mixed regulatory circuits (2012 update)

PubMed Central

Bisognin, Andrea; Sales, Gabriele; Coppe, Alessandro; Bortoluzzi, Stefania; Romualdi, Chiara

2012-01-01

MAGIA2 (http://gencomp.bio.unipd.it/magia2) is an update, extension and evolution of the MAGIA web tool. It is dedicated to the integrated analysis of in silico target prediction, microRNA (miRNA) and gene expression data for the reconstruction of post-transcriptional regulatory networks. miRNAs are fundamental post-transcriptional regulators of several key biological and pathological processes. As miRNAs act prevalently through target degradation, their expression profiles are expected to be inversely correlated to those of the target genes. Low specificity of target prediction algorithms makes integration approaches an interesting solution for target prediction refinement. MAGIA2 performs this integrative approach supporting different association measures, multiple organisms and almost all target predictions algorithms. Nevertheless, miRNAs activity should be viewed as part of a more complex scenario where regulatory elements and their interactors generate a highly connected network and where gene expression profiles are the result of different levels of regulation. The updated MAGIA2 tries to dissect this complexity by reconstructing mixed regulatory circuits involving either miRNA or transcription factor (TF) as regulators. Two types of circuits are identified: (i) a TF that regulates both a miRNA and its target and (ii) a miRNA that regulates both a TF and its target. PMID:22618880

Differential expression of lncRNAs during the HIV replication cycle: an underestimated layer in the HIV-host interplay.

PubMed

Trypsteen, Wim; Mohammadi, Pejman; Van Hecke, Clarissa; Mestdagh, Pieter; Lefever, Steve; Saeys, Yvan; De Bleser, Pieter; Vandesompele, Jo; Ciuffi, Angela; Vandekerckhove, Linos; De Spiegelaere, Ward

2016-10-26

Studying the effects of HIV infection on the host transcriptome has typically focused on protein-coding genes. However, recent advances in the field of RNA sequencing revealed that long non-coding RNAs (lncRNAs) add an extensive additional layer to the cell's molecular network. Here, we performed transcriptome profiling throughout a primary HIV infection in vitro to investigate lncRNA expression at the different HIV replication cycle processes (reverse transcription, integration and particle production). Subsequently, guilt-by-association, transcription factor and co-expression analysis were performed to infer biological roles for the lncRNAs identified in the HIV-host interplay. Many lncRNAs were suggested to play a role in mechanisms relying on proteasomal and ubiquitination pathways, apoptosis, DNA damage responses and cell cycle regulation. Through transcription factor binding analysis, we found that lncRNAs display a distinct transcriptional regulation profile as compared to protein coding mRNAs, suggesting that mRNAs and lncRNAs are independently modulated. In addition, we identified five differentially expressed lncRNA-mRNA pairs with mRNA involvement in HIV pathogenesis with possible cis regulatory lncRNAs that control nearby mRNA expression and function. Altogether, the present study demonstrates that lncRNAs add a new dimension to the HIV-host interplay and should be further investigated as they may represent targets for controlling HIV replication.

The exosome component Rrp6 is required for RNA polymerase II termination at specific targets of the Nrd1-Nab3 pathway.

PubMed

Fox, Melanie J; Gao, Hongyu; Smith-Kinnaman, Whitney R; Liu, Yunlong; Mosley, Amber L

2015-01-01

The exosome and its nuclear specific subunit Rrp6 form a 3'-5' exonuclease complex that regulates diverse aspects of RNA biology including 3' end processing and degradation of a variety of noncoding RNAs (ncRNAs) and unstable transcripts. Known targets of the nuclear exosome include short (<1000 bp) RNAPII transcripts such as small noncoding RNAs (snRNAs), cryptic unstable transcripts (CUTs), and some stable unannotated transcripts (SUTs) that are terminated by an Nrd1, Nab3, and Sen1 (NNS) dependent mechanism. NNS-dependent termination is coupled to RNA 3' end processing and/or degradation by the Rrp6/exosome in yeast. Recent work suggests Nrd1 is necessary for transcriptome surveillance, regulating promoter directionality and suppressing antisense transcription independently of, or prior to, Rrp6 activity. It remains unclear whether Rrp6 is directly involved in termination; however, Rrp6 has been implicated in the 3' end processing and degradation of ncRNA transcripts including CUTs. To determine the role of Rrp6 in NNS termination globally, we performed RNA sequencing (RNA-Seq) on total RNA and perform ChIP-exo analysis of RNA Polymerase II (RNAPII) localization. Deletion of RRP6 promotes hyper-elongation of multiple NNS-dependent transcripts resulting from both improperly processed 3' RNA ends and faulty transcript termination at specific target genes. The defects in RNAPII termination cause transcriptome-wide changes in mRNA expression through transcription interference and/or antisense repression, similar to previously reported effects of depleting Nrd1 from the nucleus. Elongated transcripts were identified within all classes of known NNS targets with the largest changes in transcription termination occurring at CUTs. Interestingly, the extended transcripts that we have detected in our studies show remarkable similarity to Nrd1-unterminated transcripts at many locations, suggesting that Rrp6 acts with the NNS complex globally to promote transcription termination in addition to 3' end RNA processing and/or degradation at specific targets.

A single point mutation in cyclin T1 eliminates binding to Hexim1, Cdk9 and RNA but not to AFF4 and enforces repression of HIV transcription

PubMed Central

2014-01-01

Background Human immunodeficiency virus (HIV) gene expression is primarily regulated at the step of transcription elongation. The viral Tat protein recruits the Positive Transcription Elongation Factor b (P-TEFb) and the Super Elongation Complex (SEC) to the HIV promoter and enhances transcription by host RNA polymerase II. Results To map residues in the cyclin box of cyclin T1 that mediate the binding of P-TEFb to its interacting host partners and support HIV transcription, a pool of N-terminal cyclin T1 mutants was generated. Binding and functional assays in cells identified specific positions in cyclin T1 that are important for (i) association of P-TEFb with Hexim1, Cdk9 and SEC/AFF4 (ii) supporting Tat-transactivation in murine cells and (iii) inhibition of basal and Tat-dependent HIV transcription in human cells. Significantly, a unique cyclin T1 mutant where a Valine residue at position 107 was mutated to Glutamate (CycT1-V107E) was identified. CycT1-V107E did not bind to Hexim1 or Cdk9, and also could not assemble on HIV TAR or 7SK-snRNA. However, it bound strongly to AFF4 and its association with HIV Tat was slightly impaired. CycT1-V107E efficiently inhibited HIV replication in human T cell lines and in CD4(+) primary cells, and enforced HIV transcription repression in T cell lines that harbor a transcriptionally silenced integrated provirus. Conclusions This study outlines the mechanism by which CycT1-V107E mutant inhibits HIV transcription and enforces viral latency. It defines the importance of N-terminal residues of cyclin T1 in mediating contacts of P-TEFb with its transcription partners, and signifies the requirement of a functional P-TEFb and SEC in mediating HIV transcription. PMID:24985467

A single point mutation in cyclin T1 eliminates binding to Hexim1, Cdk9 and RNA but not to AFF4 and enforces repression of HIV transcription.

PubMed

Kuzmina, Alona; Verstraete, Nina; Galker, Sigal; Maatook, Maayan; Bensaude, Olivier; Taube, Ran

2014-07-01

Human immunodeficiency virus (HIV) gene expression is primarily regulated at the step of transcription elongation. The viral Tat protein recruits the Positive Transcription Elongation Factor b (P-TEFb) and the Super Elongation Complex (SEC) to the HIV promoter and enhances transcription by host RNA polymerase II. To map residues in the cyclin box of cyclin T1 that mediate the binding of P-TEFb to its interacting host partners and support HIV transcription, a pool of N-terminal cyclin T1 mutants was generated. Binding and functional assays in cells identified specific positions in cyclin T1 that are important for (i) association of P-TEFb with Hexim1, Cdk9 and SEC/AFF4 (ii) supporting Tat-transactivation in murine cells and (iii) inhibition of basal and Tat-dependent HIV transcription in human cells. Significantly, a unique cyclin T1 mutant where a Valine residue at position 107 was mutated to Glutamate (CycT1-V107E) was identified. CycT1-V107E did not bind to Hexim1 or Cdk9, and also could not assemble on HIV TAR or 7SK-snRNA. However, it bound strongly to AFF4 and its association with HIV Tat was slightly impaired. CycT1-V107E efficiently inhibited HIV replication in human T cell lines and in CD4(+) primary cells, and enforced HIV transcription repression in T cell lines that harbor a transcriptionally silenced integrated provirus. This study outlines the mechanism by which CycT1-V107E mutant inhibits HIV transcription and enforces viral latency. It defines the importance of N-terminal residues of cyclin T1 in mediating contacts of P-TEFb with its transcription partners, and signifies the requirement of a functional P-TEFb and SEC in mediating HIV transcription.

Microprocessor mediates transcriptional termination of long noncoding RNA transcripts hosting microRNAs.

PubMed

Dhir, Ashish; Dhir, Somdutta; Proudfoot, Nick J; Jopling, Catherine L

2015-04-01

MicroRNAs (miRNAs) play a major part in the post-transcriptional regulation of gene expression. Mammalian miRNA biogenesis begins with cotranscriptional cleavage of RNA polymerase II (Pol II) transcripts by the Microprocessor complex. Although most miRNAs are located within introns of protein-coding transcripts, a substantial minority of miRNAs originate from long noncoding (lnc) RNAs, for which transcript processing is largely uncharacterized. We show, by detailed characterization of liver-specific lnc-pri-miR-122 and genome-wide analysis in human cell lines, that most lncRNA transcripts containing miRNAs (lnc-pri-miRNAs) do not use the canonical cleavage-and-polyadenylation pathway but instead use Microprocessor cleavage to terminate transcription. Microprocessor inactivation leads to extensive transcriptional readthrough of lnc-pri-miRNA and transcriptional interference with downstream genes. Consequently we define a new RNase III-mediated, polyadenylation-independent mechanism of Pol II transcription termination in mammalian cells.

Structural organization of poliovirus RNA replication is mediated by viral proteins of the P2 genomic region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bienz, K.; Egger, D.; Troxler, M.

1990-03-01

Transcriptionally active replication complexes bound to smooth membrane vesicles were isolated from poliovirus-infected cells. In electron microscopic, negatively stained preparations, the replication complex appeared as an irregularly shaped, oblong structure attached to several virus-induced vesicles of a rosettelike arrangement. Electron microscopic immunocytochemistry of such preparations demonstrated that the poliovirus replication complex contains the proteins coded by the P2 genomic region (P2 proteins) in a membrane-associated form. In addition, the P2 proteins are also associated with viral RNA, and they can be cross-linked to viral RNA by UV irradiation. Guanidine hydrochloride prevented the P2 proteins from becoming membrane bound but didmore » not change their association with viral RNA. The findings allow the conclusion that the protein 2C or 2C-containing precursor(s) is responsible for the attachment of the viral RNA to the vesicular membrane and for the spatial organization of the replication complex necessary for its proper functioning in viral transcription. A model for the structure of the viral replication complex and for the function of the 2C-containing P2 protein(s) and the vesicular membranes is proposed.« less

Affinity Isolation and I-DIRT Mass Spectrometric Analysis of the Escherichia coli O157:H7 Sakai RNA Polymerase Complex▿

PubMed Central

Lee, David J.; Busby, Stephen J. W.; Westblade, Lars F.; Chait, Brian T.

2008-01-01

Bacteria contain a single multisubunit RNA polymerase that is responsible for the synthesis of all RNA. Previous studies of the Escherichia coli K-12 laboratory strain identified a group of effector proteins that interact directly with RNA polymerase to modulate the efficiency of transcription initiation, elongation, or termination. Here we used a rapid affinity isolation technique to isolate RNA polymerase from the pathogenic Escherichia coli strain O157:H7 Sakai. We analyzed the RNA polymerase enzyme complex using mass spectrometry and identified associated proteins. Although E. coli O157:H7 Sakai contains more than 1,600 genes not present in the K-12 strain, many of which are predicted to be involved in transcription regulation, all of the identified proteins in this study were encoded on the “core” E. coli genome. PMID:18083804

Affinity isolation and I-DIRT mass spectrometric analysis of the Escherichia coli O157:H7 Sakai RNA polymerase complex.

PubMed

Lee, David J; Busby, Stephen J W; Westblade, Lars F; Chait, Brian T

2008-02-01

Bacteria contain a single multisubunit RNA polymerase that is responsible for the synthesis of all RNA. Previous studies of the Escherichia coli K-12 laboratory strain identified a group of effector proteins that interact directly with RNA polymerase to modulate the efficiency of transcription initiation, elongation, or termination. Here we used a rapid affinity isolation technique to isolate RNA polymerase from the pathogenic Escherichia coli strain O157:H7 Sakai. We analyzed the RNA polymerase enzyme complex using mass spectrometry and identified associated proteins. Although E. coli O157:H7 Sakai contains more than 1,600 genes not present in the K-12 strain, many of which are predicted to be involved in transcription regulation, all of the identified proteins in this study were encoded on the "core" E. coli genome.

Quantifying circular RNA expression from RNA-seq data using model-based framework.

PubMed

Li, Musheng; Xie, Xueying; Zhou, Jing; Sheng, Mengying; Yin, Xiaofeng; Ko, Eun-A; Zhou, Tong; Gu, Wanjun

2017-07-15

Circular RNAs (circRNAs) are a class of non-coding RNAs that are widely expressed in various cell lines and tissues of many organisms. Although the exact function of many circRNAs is largely unknown, the cell type-and tissue-specific circRNA expression has implicated their crucial functions in many biological processes. Hence, the quantification of circRNA expression from high-throughput RNA-seq data is becoming important to ascertain. Although many model-based methods have been developed to quantify linear RNA expression from RNA-seq data, these methods are not applicable to circRNA quantification. Here, we proposed a novel strategy that transforms circular transcripts to pseudo-linear transcripts and estimates the expression values of both circular and linear transcripts using an existing model-based algorithm, Sailfish. The new strategy can accurately estimate transcript expression of both linear and circular transcripts from RNA-seq data. Several factors, such as gene length, amount of expression and the ratio of circular to linear transcripts, had impacts on quantification performance of circular transcripts. In comparison to count-based tools, the new computational framework had superior performance in estimating the amount of circRNA expression from both simulated and real ribosomal RNA-depleted (rRNA-depleted) RNA-seq datasets. On the other hand, the consideration of circular transcripts in expression quantification from rRNA-depleted RNA-seq data showed substantial increased accuracy of linear transcript expression. Our proposed strategy was implemented in a program named Sailfish-cir. Sailfish-cir is freely available at https://github.com/zerodel/Sailfish-cir . tongz@medicine.nevada.edu or wanjun.gu@gmail.com. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Human transcription factor hTAF(II)150 (CIF150) is involved in transcriptional regulation of cell cycle progression.

PubMed

Martin, J; Halenbeck, R; Kaufmann, J

1999-08-01

Here we present evidence that CIF150 (hTAF(II)150), the human homolog of Drosophila TAF(II)150, plays an important and selective role in establishing gene expression patterns necessary for progression through the cell cycle. Gel filtration experiments demonstrate that CIF150 (hTAF(II)150) seems to be less tightly associated with human transcription factor IID than hTAF(II)130 is associated with hTAF(II)250. The transient functional knockout of CIF150 (hTAF(II)150) protein led to cell cycle arrest at the G(2)/M transition in mammalian cell lines. PCR display analysis with the RNA derived from CIF150-depleted cells indicated that CIF150 (hTAF(II)150) is required for the transcription of only a subset of RNA polymerase II genes. CIF150 (hTAF(II)150) directly stimulated cyclin B1 and cyclin A transcription in cotransfection assays and in vitro assays, suggesting that the expression of these genes is dependent on CIF150 (hTAF(II)150) function. We defined a CIF150 (hTAF(II)150) consensus binding site and demonstrated that a CIF150-responsive cis element is present in the cyclin B1 core promoter. These results suggest that one function of CIF150 (hTAF(II)150) is to select specific RNA polymerase II core promoter elements involved in cell cycle progression.

Human Transcription Factor hTAFII150 (CIF150) Is Involved in Transcriptional Regulation of Cell Cycle Progression

PubMed Central

Martin, Jay; Halenbeck, Robert; Kaufmann, Jörg

1999-01-01

Here we present evidence that CIF150 (hTAFII150), the human homolog of Drosophila TAFII150, plays an important and selective role in establishing gene expression patterns necessary for progression through the cell cycle. Gel filtration experiments demonstrate that CIF150 (hTAFII150) seems to be less tightly associated with human transcription factor IID than hTAFII130 is associated with hTAFII250. The transient functional knockout of CIF150 (hTAFII150) protein led to cell cycle arrest at the G2/M transition in mammalian cell lines. PCR display analysis with the RNA derived from CIF150-depleted cells indicated that CIF150 (hTAFII150) is required for the transcription of only a subset of RNA polymerase II genes. CIF150 (hTAFII150) directly stimulated cyclin B1 and cyclin A transcription in cotransfection assays and in vitro assays, suggesting that the expression of these genes is dependent on CIF150 (hTAFII150) function. We defined a CIF150 (hTAFII150) consensus binding site and demonstrated that a CIF150-responsive cis element is present in the cyclin B1 core promoter. These results suggest that one function of CIF150 (hTAFII150) is to select specific RNA polymerase II core promoter elements involved in cell cycle progression. PMID:10409744

Functional Analyses of c.2268dup in Thyroid Peroxidase Gene Associated with Goitrous Congenital Hypothyroidism

PubMed Central

Harun, Fatimah; Jalaludin, Muhammad Yazid; Lim, Chor Yin; Ng, Khoon Leong

2014-01-01

The c.2268dup mutation in thyroid peroxidase (TPO) gene was reported to be a founder mutation in Taiwanese patients with dyshormonogenetic congenital hypothyroidism (CH). The functional impact of the mutation is not well documented. In this study, homozygous c.2268dup mutation was detected in two Malaysian-Chinese sisters with goitrous CH. Normal and alternatively spliced TPO mRNA transcripts were present in thyroid tissues of the two sisters. The abnormal transcript contained 34 nucleotides originating from intron 12. The c.2268dup is predicted to generate a premature termination codon (PTC) at position 757 (p.Glu757X). Instead of restoring the normal reading frame, the alternatively spliced transcript has led to another stop codon at position 740 (p.Asp739ValfsX740). The two PTCs are located at 116 and 201 nucleotides upstream of the exons 13/14 junction fulfilling the requirement for a nonsense-mediated mRNA decay (NMD). Quantitative RT-PCR revealed an abundance of unidentified transcripts believed to be associated with the NMD. TPO enzyme activity was not detected in both patients, even though a faint TPO band of about 80 kD was present. In conclusion, the c.2268dup mutation leads to the formation of normal and alternatively spliced TPO mRNA transcripts with a consequential loss of TPO enzymatic activity in Malaysian-Chinese patients with goitrous CH. PMID:24745015

Synergies between RNA degradation and trans-translation in Streptococcus pneumoniae: cross regulation and co-transcription of RNase R and SmpB

PubMed Central

2012-01-01

Background Ribonuclease R (RNase R) is an exoribonuclease that recognizes and degrades a wide range of RNA molecules. It is a stress-induced protein shown to be important for the establishment of virulence in several pathogenic bacteria. RNase R has also been implicated in the trans-translation process. Transfer-messenger RNA (tmRNA/SsrA RNA) and SmpB are the main effectors of trans-translation, an RNA and protein quality control system that resolves challenges associated with stalled ribosomes on non-stop mRNAs. Trans-translation has also been associated with deficiencies in stress-response mechanisms and pathogenicity. Results In this work we study the expression of RNase R in the human pathogen Streptococcus pneumoniae and analyse the interplay of this enzyme with the main components of the trans-translation machinery (SmpB and tmRNA/SsrA). We show that RNase R is induced after a 37°C to 15°C temperature downshift and that its levels are dependent on SmpB. On the other hand, our results revealed a strong accumulation of the smpB transcript in the absence of RNase R at 15°C. Transcriptional analysis of the S. pneumoniae rnr gene demonstrated that it is co-transcribed with the flanking genes, secG and smpB. Transcription of these genes is driven from a promoter upstream of secG and the transcript is processed to yield mature independent mRNAs. This genetic organization seems to be a common feature of Gram positive bacteria, and the biological significance of this gene cluster is further discussed. Conclusions This study unravels an additional contribution of RNase R to the trans-translation system by demonstrating that smpB is regulated by this exoribonuclease. RNase R in turn, is shown to be under the control of SmpB. These proteins are therefore mutually dependent and cross-regulated. The data presented here shed light on the interactions between RNase R, trans-translation and cold-shock response in an important human pathogen. PMID:23167513

Characterization of herpes simplex virus type 2 latency-associated transcription in human sacral ganglia and in cell culture.

PubMed

Croen, K D; Ostrove, J M; Dragovic, L; Straus, S E

1991-01-01

The ability of herpes simplex virus type 2 (HSV-2) to establish latency in and reactivate from sacral dorsal root sensory ganglia is the basis for recurrent genital herpes. The expression of HSV-2 genes in latently infected human sacral ganglia was investigated by in situ hybridization. Hybridizations with a probe from the long repeat region of HSV-2 revealed strong nuclear signals overlying neurons in sacral ganglia from five of nine individuals. The RNA detected overlaps with the transcript for infected cell protein O but in the opposite, or "anti-sense," orientation. These observations mimic those made previously with HSV-1 in human trigeminal ganglia and confirm the recent findings during latency in HSV-2-infected mice and guinea pigs. Northern hybridization of RNA from infected Vero cells showed that an HSV-2 latency-associated transcript was similar in size to the larger (1.85 kb) latency transcript of HSV-1. Thus, HSV-1 and HSV-2 latency in human sensory ganglia are similar, if not identical, in terms of their cellular localization and pattern of transcription.

Simultaneous detection of four causal agents of tobacco bushy top disease by a multiplex one-step RT-PCR

USDA-ARS?s Scientific Manuscript database

Tobacco bushy top disease is a complex disease caused by mixed infection of Tobacco bushy top virus (TBTV), Tobacco vein distorting virus (TVDV), satellite RNA of TBTV (Sat-TBTV) and Tobacco vein distorting virus associate RNA (TVDVaRNA). A one-tube multiplex reverse transcription-PCR (RT-PCR) assay...

Activation of RNA Polymerase III Transcription in Cells Transformed by Simian Virus 40

PubMed Central

Larminie, Christopher G. C.; Sutcliffe, Josephine E.; Tosh, Kerrie; Winter, Andrew G.; Felton-Edkins, Zoe A.; White, Robert J.

1999-01-01

RNA polymerase (Pol) III transcription is abnormally active in fibroblasts that have been transformed by simian virus 40 (SV40). This report presents evidence that two separate components of the general Pol III transcription apparatus, TFIIIB and TFIIIC2, are deregulated following SV40 transformation. TFIIIC2 subunits are expressed at abnormally high levels in SV40-transformed cells, an effect which is observed at both protein and mRNA levels. In untransformed fibroblasts, TFIIIB is subject to repression through association with the retinoblastoma protein RB. The interaction between RB and TFIIIB is compromised following SV40 transformation. Furthermore, the large T antigen of SV40 is shown to relieve repression by RB. The E7 oncoprotein of human papillomavirus can also activate Pol III transcription, an effect that is dependent on its ability to bind to RB. The data provide evidence that both TFIIIB and TFIIIC2 are targets for activation by DNA tumor viruses. PMID:10373542

Defining the Transcriptional Landscape during Cytomegalovirus Latency with Single-Cell RNA Sequencing

PubMed Central

2018-01-01

ABSTRACT Primary infection with human cytomegalovirus (HCMV) results in a lifelong infection due to its ability to establish latent infection, with one characterized viral reservoir being hematopoietic cells. Although reactivation from latency causes serious disease in immunocompromised individuals, our molecular understanding of latency is limited. Here, we delineate viral gene expression during natural HCMV persistent infection by analyzing the massive transcriptome RNA sequencing (RNA-seq) atlas generated by the Genotype-Tissue Expression (GTEx) project. This systematic analysis reveals that HCMV persistence in vivo is prevalent in diverse tissues. Notably, we find only viral transcripts that resemble gene expression during various stages of lytic infection with no evidence of any highly restricted latency-associated viral gene expression program. To further define the transcriptional landscape during HCMV latent infection, we also used single-cell RNA-seq and a tractable experimental latency model. In contrast to some current views on latency, we also find no evidence for any highly restricted latency-associated viral gene expression program. Instead, we reveal that latency-associated gene expression largely mirrors a late lytic viral program, albeit at much lower levels of expression. Overall, our work has the potential to revolutionize our understanding of HCMV persistence and suggests that latency is governed mainly by quantitative changes, with a limited number of qualitative changes, in viral gene expression. PMID:29535194

Genome-wide mRNA processing in methanogenic archaea reveals post-transcriptional regulation of ribosomal protein synthesis.

PubMed

Qi, Lei; Yue, Lei; Feng, Deqin; Qi, Fengxia; Li, Jie; Dong, Xiuzhu

2017-07-07

Unlike stable RNAs that require processing for maturation, prokaryotic cellular mRNAs generally follow an 'all-or-none' pattern. Herein, we used a 5΄ monophosphate transcript sequencing (5΄P-seq) that specifically captured the 5΄-end of processed transcripts and mapped the genome-wide RNA processing sites (PSSs) in a methanogenic archaeon. Following statistical analysis and stringent filtration, we identified 1429 PSSs, among which 23.5% and 5.4% were located in 5΄ untranslated region (uPSS) and intergenic region (iPSS), respectively. A predominant uridine downstream PSSs served as a processing signature. Remarkably, 5΄P-seq detected overrepresented uPSS and iPSS in the polycistronic operons encoding ribosomal proteins, and the majority upstream and proximal ribosome binding sites, suggesting a regulatory role of processing on translation initiation. The processed transcripts showed increased stability and translation efficiency. Particularly, processing within the tricistronic transcript of rplA-rplJ-rplL enhanced the translation of rplL, which can provide a driving force for the 1:4 stoichiometry of L10 to L12 in the ribosome. Growth-associated mRNA processing intensities were also correlated with the cellular ribosomal protein levels, thereby suggesting that mRNA processing is involved in tuning growth-dependent ribosome synthesis. In conclusion, our findings suggest that mRNA processing-mediated post-transcriptional regulation is a potential mechanism of ribosomal protein synthesis and stoichiometry. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Complete Genome Sequence of Diaphorina citri-associated C virus, a Novel Putative RNA Virus of the Asian Citrus Psyllid, Diaphorina citri.

PubMed

Nouri, Shahideh; Salem, Nidà; Falk, Bryce W

2016-07-21

We present here the complete nucleotide sequence and genome organization of a novel putative RNA virus identified in field populations of the Asian citrus psyllid, Diaphorina citri, through sequencing of the transcriptome followed by reverse transcription-PCR (RT-PCR). We tentatively named this virus Diaphorina citri-associated C virus (DcACV). DcACV is an unclassified positive-sense RNA virus. Copyright © 2016 Nouri et al.

RNA polymerase II transcriptional fidelity control and its functional interplay with DNA modifications

PubMed Central

Xu, Liang; Wang, Wei; Chong, Jenny; Shin, Ji Hyun; Xu, Jun; Wang, Dong

2016-01-01

Accurate genetic information transfer is essential for life. As a key enzyme involved in the first step of gene expression, RNA polymerase II (Pol II) must maintain high transcriptional fidelity while it reads along DNA template and synthesizes RNA transcript in a stepwise manner during transcription elongation. DNA lesions or modifications may lead to significant changes in transcriptional fidelity or transcription elongation dynamics. In this review, we will summarize recent progress towards understanding the molecular basis of RNA Pol II transcriptional fidelity control and impacts of DNA lesions and modifications on Pol II transcription elongation. PMID:26392149

Expression and methylation of BDNF in the human brain in schizophrenia.

PubMed

Cheah, Sern-Yih; McLeay, Robert; Wockner, Leesa F; Lawford, Bruce R; Young, Ross McD; Morris, Charles P; Voisey, Joanne

2017-08-01

To examine the combined effect of the BDNF Val66Met (rs6265) polymorphism and BDNF DNA methylation on transcriptional regulation of the BDNF gene. DNA methylation profiles were generated for CpG sites proximal to Val66Met, within BDNF promoter I and exon V for prefrontal cortex samples from 25 schizophrenia and 25 control subjects. Val66Met genotypes and BDNF mRNA expression data were generated by transcriptome sequencing. Expression, methylation and genotype data were correlated and examined for association with schizophrenia. There was 43% more of the BDNF V-VIII-IX transcript in schizophrenia samples. BDNF mRNA expression and DNA methylation of seven CpG sites were not associated with schizophrenia after accounting for age and PMI effects. BDNF mRNA expression and DNA methylation were not altered by Val66Met after accounting for age and PMI effects. DNA methylation of one CpG site had a marginally significant positive correlation with mRNA expression in schizophrenia subjects. Schizophrenia risk was not associated with differential BDNF mRNA expression and DNA methylation. A larger age-matched cohort with comprehensive clinical history is required to accurately identify the effects of genotype, mRNA expression and DNA methylation on schizophrenia risk.

Long noncoding RNA myocardial infarction‑associated transcript is associated with the microRNA‑150‑5p/P300 pathway in cardiac hypertrophy.

PubMed

Li, Zhao; Liu, Yamin; Guo, Xiaofan; Sun, Guozhe; Ma, Qun; Dai, Ying; Zhu, Guangshuo; Sun, Yingxian

2018-05-21

In numerous diseases, abnormal expression of myocardial infarction‑associated transcript (MIAT) has been reported to be involved in cell proliferation, apoptosis and migration. However, whether this long non‑coding RNA MIAT has a regulatory effect on heart hypertrophy requires further investigation. To this end, the present study evaluated MIAT in hypertrophic cardiomyocytes in vitro and in vivo. Neonatal rat ventricular myocytes (NRVMs) were induced by isoproterenol (ISO) to create a cell hypertrophy model, and mice were intraperitoneally injected with ISO to establish an animal model. Echocardiography, immunofluorescence staining, western blot analysis, RNA isolation and reverse transcription‑polymerase chain reaction were applied to test the involvement of MIAT in cardiac hypertrophy. The results revealed that MIAT was upregulated under ISO stimulation at the mRNA level both in vivo and in vitro. Silencing of MIAT resulted in decreased expression levels of atrial natriuretic peptide and brain natriuretic peptide in ISO‑treated NRVM cardiomyocytes, confirming the connection between MIAT and hypertrophy. Furthermore, MIAT small interfering RNA significantly increased microRNA (miR)‑150 and decreased P300 expression in NRVMs. In conclusion, the MIAT/miR‑150‑5p axis targets P300 as a positive regulator of cardiomyocyte hypertrophy.

Pseudogene PHBP1 promotes esophageal squamous cell carcinoma proliferation by increasing its cognate gene PHB expression.

PubMed

Feng, Feiyue; Qiu, Bin; Zang, Ruochuan; Song, Peng; Gao, Shugeng

2017-04-25

Natural antisense transcripts (NATs) as one of the most diverse classes of long noncoding RNAs (lncRNAs), have been demonstrated involved in fundamental biological processes in human. Here, we reported that human prohibitin gene pseudogene 1 (PHBP1) was upregulated in ESCC, and increased PHBP1 expression in ESCC was associated with clinical advanced stage. Functional experiments showed that PHBP1 knockdown inhibited ESCC cells proliferation, colony formation and xenograft tumor growth in vitro and in vivo by causing cell-cycle arrest at the G1-G0 phase. Mechanisms analysis revealed that PHBP1 transcript as an antisense transcript of PHB is partially complementary to PHB mRNA and formed an RNA-RNA hybrid with PHB, consequently inducing an increase of PHB expression at both the mRNA and protein levels. Furthermore, PHBP1 expression is strongly correlated with PHB expression in ESCC tissues. Collectively, this study elucidates an important role of PHBP1 in promoting ESCC partly via increasing PHB expression.

A Small RNA-Catalytic Argonaute Pathway Tunes Germline Transcript Levels to Ensure Embryonic Divisions

PubMed Central

Gerson-Gurwitz, Adina; Wang, Shaohe; Sathe, Shashank; Green, Rebecca; Yeo, Gene W.; Oegema, Karen; Desai, Arshad

2016-01-01

SUMMARY Multiple division cycles without growth are a characteristic feature of early embryogenesis. The female germline loads proteins and RNAs into oocytes to support these divisions, which lack many quality control mechanisms operating in somatic cells undergoing growth. Here we describe a small RNA-Argonaute pathway that ensures early embryonic divisions in C. elegans by employing catalytic slicing activity to broadly tune, instead of silence, germline gene expression. Misregulation of one target, a kinesin-13 microtubule depolymerase, underlies a major phenotype associated with pathway loss. Tuning of target transcript levels is guided by density of homologous small RNAs, whose generation must ultimately be related to target sequence. Thus, the tuning action of a small RNA-catalytic Argonaute pathway generates oocytes capable of supporting embryogenesis. We speculate that the specialized nature of germline chromatin led to emergence of small RNA-catalytic Argonaute pathways in the female germline as a post-transcriptional control layer to optimize oocyte composition. PMID:27020753

Loss of Sfpq Causes Long-Gene Transcriptopathy in the Brain.

PubMed

Takeuchi, Akihide; Iida, Kei; Tsubota, Toshiaki; Hosokawa, Motoyasu; Denawa, Masatsugu; Brown, J B; Ninomiya, Kensuke; Ito, Mikako; Kimura, Hiroshi; Abe, Takaya; Kiyonari, Hiroshi; Ohno, Kinji; Hagiwara, Masatoshi

2018-05-01

Genes specifically expressed in neurons contain members with extended long introns. Longer genes present a problem with respect to fulfilment of gene length transcription, and evidence suggests that dysregulation of long genes is a mechanism underlying neurodegenerative and psychiatric disorders. Here, we report the discovery that RNA-binding protein Sfpq is a critical factor for maintaining transcriptional elongation of long genes. We demonstrate that Sfpq co-transcriptionally binds to long introns and is required for sustaining long-gene transcription by RNA polymerase II through mediating the interaction of cyclin-dependent kinase 9 with the elongation complex. Phenotypically, Sfpq disruption caused neuronal apoptosis in developing mouse brains. Expression analysis of Sfpq-regulated genes revealed specific downregulation of developmentally essential neuronal genes longer than 100 kb in Sfpq-disrupted brains; those genes are enriched in associations with neurodegenerative and psychiatric diseases. The identified molecular machinery yields directions for targeted investigations of the association between long-gene transcriptopathy and neuronal diseases. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Cyclin-dependent Kinase 9 Links RNA Polymerase II Transcription to Processing of Ribosomal RNA*

PubMed Central

Burger, Kaspar; Mühl, Bastian; Rohrmoser, Michaela; Coordes, Britta; Heidemann, Martin; Kellner, Markus; Gruber-Eber, Anita; Heissmeyer, Vigo; Strässer, Katja; Eick, Dirk

2013-01-01

Ribosome biogenesis is a process required for cellular growth and proliferation. Processing of ribosomal RNA (rRNA) is highly sensitive to flavopiridol, a specific inhibitor of cyclin-dependent kinase 9 (Cdk9). Cdk9 has been characterized as the catalytic subunit of the positive transcription elongation factor b (P-TEFb) of RNA polymerase II (RNAPII). Here we studied the connection between RNAPII transcription and rRNA processing. We show that inhibition of RNAPII activity by α-amanitin specifically blocks processing of rRNA. The block is characterized by accumulation of 3′ extended unprocessed 47 S rRNAs and the entire inhibition of other 47 S rRNA-specific processing steps. The transcription rate of rRNA is moderately reduced after inhibition of Cdk9, suggesting that defective 3′ processing of rRNA negatively feeds back on RNAPI transcription. Knockdown of Cdk9 caused a strong reduction of the levels of RNAPII-transcribed U8 small nucleolar RNA, which is essential for 3′ rRNA processing in mammalian cells. Our data demonstrate a pivotal role of Cdk9 activity for coupling of RNAPII transcription with small nucleolar RNA production and rRNA processing. PMID:23744076

Nucleoplasmic Nup98 controls gene expression by regulating a DExH/D-box protein.

PubMed

Capitanio, Juliana S; Montpetit, Ben; Wozniak, Richard W

2018-01-01

The nucleoporin Nup98 has been linked to the regulation of transcription and RNA metabolism, 1-3 but the mechanisms by which Nup98 contributes to these processes remains largely undefined. Recently, we uncovered interactions between Nup98 and several DExH/D-box proteins (DBPs), a protein family well-known for modulating gene expression and RNA metabolism. 4-6 Analysis of Nup98 and one of these DBPs, DHX9, showed that they directly interact, their association is facilitated by RNA, and Nup98 binding stimulates DHX9 ATPase activity. 7 Furthermore, these proteins were dependent on one another for their proper association with a subset of gene loci to control transcription and modulate mRNA splicing. 7 On the basis of these observations, we proposed that Nup98 functions to regulate DHX9 activity within the nucleoplasm. 7 Since Nup98 is associated with several DBPs, regulation of DHX9 by Nup98 may represent a paradigm for understanding how Nup98, and possibly other FG-Nup proteins, could direct the diverse cellular activities of multiple DBPs.

Promoter- and RNA polymerase II–dependent hsp-16 gene association with nuclear pores in Caenorhabditis elegans

PubMed Central

Rohner, Sabine; Kalck, Veronique; Wang, Xuefei; Ikegami, Kohta; Lieb, Jason D.; Meister, Peter

2013-01-01

Some inducible yeast genes relocate to nuclear pores upon activation, but the general relevance of this phenomenon has remained largely unexplored. Here we show that the bidirectional hsp-16.2/41 promoter interacts with the nuclear pore complex upon activation by heat shock in the nematode Caenorhabditis elegans. Direct pore association was confirmed by both super-resolution microscopy and chromatin immunoprecipitation. The hsp-16.2 promoter was sufficient to mediate perinuclear positioning under basal level conditions of expression, both in integrated transgenes carrying from 1 to 74 copies of the promoter and in a single-copy genomic insertion. Perinuclear localization of the uninduced gene depended on promoter elements essential for induction and required the heat-shock transcription factor HSF-1, RNA polymerase II, and ENY-2, a factor that binds both SAGA and the THO/TREX mRNA export complex. After induction, colocalization with nuclear pores increased significantly at the promoter and along the coding sequence, dependent on the same promoter-associated factors, including active RNA polymerase II, and correlated with nascent transcripts. PMID:23460676

Upstream regulatory elements are necessary and sufficient for transcription of a U6 RNA gene by RNA polymerase III.

PubMed Central

Das, G; Henning, D; Wright, D; Reddy, R

1988-01-01

Whereas the genes coding for trimethyl guanosine-capped snRNAs are transcribed by RNA polymerase II, the U6 RNA genes are transcribed by RNA polymerase III. In this study, we have analyzed the cis-regulatory elements involved in the transcription of a mouse U6 snRNA gene in vitro and in frog oocytes. Transcriptional analysis of mutant U6 gene constructs showed that, unlike most known cases of polymerase III transcription, intragenic sequences except the initiation nucleotide are dispensable for efficient and accurate transcription of U6 gene in vitro. Transcription of 5' deletion mutants in vitro and in frog oocytes showed that the upstream region, within 79 bp from the initiation nucleotide, contains elements necessary for U6 gene transcription. Transcription studies were carried out in frog oocytes with U6 genes containing 5' distal sequence; these studies revealed that the distal element acts as an orientation-dependent enhancer when present upstream to the gene, while it is orientation-independent but distance-dependent enhancer when placed down-stream to the U6 gene. Analysis of 3' deletion mutants showed that the transcription termination of U6 RNA is dependent on a T cluster present on the 3' end of the gene, thus providing further support to other lines of evidence that U6 genes are transcribed by RNA polymerase III. These observations suggest the involvement of a composite of components of RNA polymerase II and III transcription machineries in the transcription of U6 genes by RNA polymerase III. Images PMID:3366121

Flowering time control: another window to the connection between antisense RNA and chromatin.

PubMed

Ietswaart, Robert; Wu, Zhe; Dean, Caroline

2012-09-01

A high proportion of all eukaryotic genes express antisense RNA (asRNA), which accumulates to varying degrees at different loci. Whether there is a general function for asRNA is unknown, but its widespread occurrence and frequent regulation by stress suggest an important role. The best-characterized plant gene exhibiting a complex antisense transcript pattern is the Arabidopsis floral regulator FLOWERING LOCUS C (FLC). Changes occur in the accumulation, splicing, and polyadenylation of this antisense transcript, termed COOLAIR, in different environments and genotypes. These changes are associated with altered chromatin regulation and differential FLC expression, provoking mechanistic comparisons with many well-studied loci in yeast and mammals. Detailed analysis of these specific examples may shed light on the complex interplay between asRNA and chromatin modifications in different genomes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Transcript levels, alternative splicing and proteolytic cleavage of TFIIIA control 5S rRNA accumulation during Arabidopsis thaliana development.

PubMed

Layat, Elodie; Cotterell, Sylviane; Vaillant, Isabelle; Yukawa, Yasushi; Tutois, Sylvie; Tourmente, Sylvette

2012-07-01

Ribosome biogenesis is critical for eukaryotic cells and requires coordinated synthesis of the protein and rRNA moieties of the ribosome, which are therefore highly regulated. 5S ribosomal RNA, an essential component of the large ribosomal subunit, is transcribed by RNA polymerase III and specifically requires transcription factor IIIA (TFIIIA). To obtain insight into the regulation of 5S rRNA transcription, we have investigated the expression of 5S rRNA and the exon-skipped (ES) and exon-including (EI) TFIIIA transcripts, two transcript isoforms that result from alternative splicing of the TFIIIA gene, and TFIIIA protein amounts with respect to requirements for 5S rRNA during development. We show that 5S rRNA quantities are regulated through distinct but complementary mechanisms operating through transcriptional and post-transcriptional control of TFIIIA transcripts as well as at the post-translational level through proteolytic cleavage of the TFIIIA protein. During the reproductive phase, high expression of the TFIIIA gene together with low proteolytic cleavage contributes to accumulation of functional, full-length TFIIIA protein, and results in 5S rRNA accumulation in the seed. In contrast, just after germination, the levels of TFIIIA-encoding transcripts are low and stable. Full-length TFIIIA protein is undetectable, and the level of 5S rRNA stored in the embryo progressively decreases. After day 4, in correlation with the reorganization of 5S rDNA chromatin to a mature state, full-length TFIIIA protein with transcriptional activity accumulates and permits de novo transcription of 5S rRNA. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

The 5'-end heterogeneity of adenovirus virus-associated RNAI contributes to the asymmetric guide strand incorporation into the RNA-induced silencing complex.

PubMed

Xu, Ning; Gkountela, Sofia; Saeed, Khalid; Akusjärvi, Göran

2009-11-01

Human Adenovirus type 5 encodes two short RNA polymerase III transcripts, the virus-associated (VA) RNAI and VA RNAII, which can adopt stable hairpin structures that resemble micro-RNA precursors. The terminal stems of the VA RNAs are processed into small RNAs (mivaRNAs) that are incorporated into RISC. It has been reported that VA RNAI has two transcription initiation sites, which produce two VA RNAI species; a major species, VA RNAI(G), which accounts for 75% of the VA RNAI pool, and a minor species, VA RNAI(A), which initiates transcription three nucleotides upstream compared to VA RNAI(G). We show that this 5'-heterogeneity results in a dramatic difference in RISC assembly. Thus, both VA RNAI(G) and VA RNAI(A) are processed by Dicer at the same position in the terminal stem generating the same 3'-strand mivaRNA. This mivaRNA is incorporated into RISC with 200-fold higher efficiency compared to the 5'-strand of mivaRNAI. Of the small number of 5'-strands used in RISC assembly only VA RNAI(A) generated active RISC complexes. We also show that the 3'-strand of mivaRNAI, although being the preferred substrate for RISC assembly, generates unstable RISC complexes with a low in vitro cleavage activity, only around 2% compared to RISC assembled on the VA RNAI(A) 5'-strand.

Trans-suppression of defense DEFB1 gene in intestinal epithelial cells following Cryptosporidium parvum infection is associated with host delivery of parasite Cdg7_FLc_1000 RNA.

PubMed

Ming, Zhenping; Gong, Ai-Yu; Wang, Yang; Zhang, Xin-Tian; Li, Min; Dolata, Courtney E; Chen, Xian-Ming

2018-03-01

To counteract host immunity, Cryptosporidium parvum has evolved multiple strategies to suppress host antimicrobial defense. One such strategy is to reduce the production of the antimicrobial peptide beta-defensin 1 (DEFB1) by host epithelial cells but the underlying mechanisms remain unclear. Recent studies demonstrate that a panel of parasite RNA transcripts of low protein-coding potential are delivered into infected host cells and may modulate host gene transcription. Using in vitro models of intestinal cryptosporidiosis, in this study, we analyzed the expression profile of host beta-defensin genes in host cells following infection. We found that C. parvum infection caused a significant downregulation of the DEFB1 gene. Interestingly, downregulation of DEFB1 gene was associated with host delivery of Cdg7_FLc_1000 RNA transcript, a C. parvum RNA that has previously demonstrated to be delivered into the nuclei of infected host cells. Knockdown of Cdg7_FLc_1000 in host cells could attenuate the trans-suppression of host DEFB1 gene and decreased the parasite burden. Therefore, our data suggest that trans-suppression of DEFB1 gene in intestinal epithelial cells following C. parvum infection involves host delivery of parasite Cdg7_FLc_1000 RNA, a process that may be relevant to the epithelial defense evasion by C. parvum at the early stage of infection.

Decreased HIV Type 1 Transcription in CCR5-Δ32 Heterozygotes During Suppressive Antiretroviral Therapy

PubMed Central

Wang, Charlene; Abdel-Mohsen, Mohamed; Strain, Matthew C.; Lada, Steven M.; Yukl, Steven; Cockerham, Leslie R.; Pilcher, Christopher D.; Hecht, Frederick M.; Sinclair, Elizabeth; Liegler, Teri; Richman, Douglas D.; Deeks, Steven G.; Pillai, Satish K.

2014-01-01

Individuals who are heterozygous for the CCR5-Δ32 mutation provide a natural model to examine the effects of reduced CCR5 expression on human immunodeficiency virus (HIV) persistence. We evaluated the HIV reservoir in 18 CCR5-Δ32 heterozygotes and 54 CCR5 wild-type individuals during suppressive antiretroviral therapy. Cell-associated HIV RNA levels (P = .035), RNA to DNA transcriptional ratios (P = .013), and frequency of detectable HIV 2–long terminal repeat circular DNA (P = .013) were significantly lower in CD4+ T cells from CCR5-Δ32 heterozygotes. Cell-associated HIV RNA was significantly correlated with CCR5 surface expression on CD4+ T cells (r2 = 0.136; P = .002). Our findings suggest that curative strategies should further explore manipulation of CCR5. PMID:24935955

Cis-Regulatory Variants Affect CHRNA5 mRNA Expression in Populations of African and European Ancestry

PubMed Central

Wang, Jen-Chyong; Spiegel, Noah; Bertelsen, Sarah; Le, Nhung; McKenna, Nicholas; Budde, John P.; Harari, Oscar; Kapoor, Manav; Brooks, Andrew; Hancock, Dana; Tischfield, Jay; Foroud, Tatiana; Bierut, Laura J.; Steinbach, Joe Henry; Edenberg, Howard J.; Traynor, Bryan J.; Goate, Alison M.

2013-01-01

Variants within the gene cluster encoding α3, α5, and β4 nicotinic receptor subunits are major risk factors for substance dependence. The strongest impact on risk is associated with variation in the CHRNA5 gene, where at least two mechanisms are at work: amino acid variation and altered mRNA expression levels. The risk allele of the non-synonymous variant (rs16969968; D398N) primarily occurs on the haplotype containing the low mRNA expression allele. In populations of European ancestry, there are approximately 50 highly correlated variants in the CHRNA5-CHRNA3-CHRNB4 gene cluster and the adjacent PSMA4 gene region that are associated with CHRNA5 mRNA levels. It is not clear which of these variants contribute to the changes in CHRNA5 transcript level. Because populations of African ancestry have reduced linkage disequilibrium among variants spanning this gene cluster, eQTL mapping in subjects of African ancestry could potentially aid in defining the functional variants that affect CHRNA5 mRNA levels. We performed quantitative allele specific gene expression using frontal cortices derived from 49 subjects of African ancestry and 111 subjects of European ancestry. This method measures allele-specific transcript levels in the same individual, which eliminates other biological variation that occurs when comparing expression levels between different samples. This analysis confirmed that substance dependence associated variants have a direct cis-regulatory effect on CHRNA5 transcript levels in human frontal cortices of African and European ancestry and identified 10 highly correlated variants, located in a 9 kb region, that are potential functional variants modifying CHRNA5 mRNA expression levels. PMID:24303001

The RNA-induced transcriptional silencing complex targets chromatin exclusively via interacting with nascent transcripts.

PubMed

Shimada, Yukiko; Mohn, Fabio; Bühler, Marc

2016-12-01

Small RNAs regulate chromatin modification and transcriptional gene silencing across the eukaryotic kingdom. Although these processes have been well studied, fundamental mechanistic aspects remain obscure. Specifically, it is unclear exactly how small RNA-loaded Argonaute protein complexes target chromatin to mediate silencing. Here, using fission yeast, we demonstrate that transcription of the target locus is essential for RNA-directed formation of heterochromatin. However, high transcriptional activity is inhibitory; thus, a transcriptional window exists that is optimal for silencing. We further found that pre-mRNA splicing is compatible with RNA-directed heterochromatin formation. However, the kinetics of pre-mRNA processing is critical. Introns close to the 5' end of a transcript that are rapidly spliced result in a bistable response whereby the target either remains euchromatic or becomes fully silenced. Together, our results discount siRNA-DNA base pairing in RNA-mediated heterochromatin formation, and the mechanistic insights further reveal guiding paradigms for the design of small RNA-directed chromatin silencing studies in multicellular organisms. © 2016 Shimada et al.; Published by Cold Spring Harbor Laboratory Press.

Relationship between variant forms of estrogen receptor RNA and an apoptosis-related RNA, TRPM-2, with survival in patients with breast cancer.

PubMed

Rennie, P S; Mawji, N R; Coldman, A J; Godolphin, W; Jones, E C; Vielkind, J R; Bruchovsky, N

1993-12-15

Although smaller variant forms of estrogen receptor (ER) messenger RNA (mRNA) have been detected in breast tumors, neither their prevalence nor their prognostic significance have been evaluated. Similarly, TRPM-2 mRNA, the product of a gene induced principally during the onset of apoptosis, is present in mouse and human breast cancer cell lines, but whether it also occurs in primary breast tumors and is related to disease outcome is unknown. The relative expression and transcript size of ER mRNA and TRPM-2 mRNA in 126 primary breast tumors were measured by Northern analysis and compared with tumor grade, hormone receptor status, extent of tumor necrosis, and survival. In ER-positive tumors, 64% of the tumors had only the normal 6.5 kb ER mRNA, an additional 9% had the normal plus smaller ER mRNA, and 2% had variant forms. Only 8% of ER-negative tumors had ER mRNA transcripts. There were significant relationships between the occurrence of ER mRNA and low tumor grade, ER-positive receptor status, and better survival. In contrast, TRPM-2 mRNA was found in only 17% of breast tumors, none of which could be grouped with respect to grade, hormone receptor status, or survival. The presence of smaller variant forms of ER mRNA either alone or in association with the normal ER transcript is not indicative of an unfavorable prognosis, whereas TRPM-2 mRNA occurs in many primary breast tumors, but has no apparent relationship to survival.

Effective reduction of the interleukin-1β transcript in osteoarthritis-prone guinea pig chondrocytes via short hairpin RNA mediated RNA interference influences gene expression of mediators implicated in disease pathogenesis

PubMed Central

Santangeloyz, K.S.; Bertoneyz, A.L.

2011-01-01

summary Objective To ascertain a viral vector-based short hairpin RNA (shRNA) capable of reducing the interleukin-1β (IL-1β) transcript in osteoarthritis (OA)-prone chondrocytes and detect corresponding changes in the expression patterns of several critical disease mediators. Methods Cultured chondrocytes from 2-month-old Hartley guinea pigs were screened for reduction of the IL-1β transcript following plasmid-based delivery of U6-driven shRNA sequences. A successful plasmid/shRNA knockdown combination was identified and used to construct an adeno-associated virus serotype 5 (AAV5) vector for further evaluation. Relative real-time reverse transcription polymerase chain reaction (RTPCR) was used to quantify in vitro transcript changes of IL-1β and an additional nine genes following transduction with this targeting knockdown vector. To validate in vitro findings, this AAV5 vector was injected into one knee, while either an equivalent volume of saline vehicle (three animals) or non-targeting control vector (three animals) were injected into opposite knees. Fold differences and subsequent percent gene expression levels relative to control groups were calculated using the comparative CT (2−ΔΔCT) method. Results Statistically significant decreases in IL-1β expression were achieved by the targeting knockdown vector relative to both the mock-transduced control and non-targeting vector control groups in vitro. Transcript levels of anabolic transforming growth factor-β (TGF-β) were significantly increased by use of this targeting knockdown vector. Transduction with this targeting AAV5 vector also significantly decreased the transcript levels of key inflammatory cytokines [tumor necrosis factor-α (TNF-α), IL-2, IL-8, and IL-12] and catabolic agents [matrix metalloproteinase (MMP)13, MMP2, interferon-γ (IFN-γ), and inducible nitrous oxide synthase (iNOS)] relative to both mock-transduced and non-targeting vector control groups. In vivo application of this targeting knockdown vector resulted in a >50% reduction (P= 0.0045) or >90% (P= 0.0001) of the IL-1β transcript relative to vehicle-only or non-targeting vector control exposed cartilage, respectively. Conclusions Successful reduction of the IL-1β transcript was achieved via RNA interference (RNAi) techniques. Importantly, this alteration significantly influenced the transcript levels of several major players involved in OA pathogenesis in the direction of disease modification. Investigations to characterize additional gene expression changes influenced by targeting knockdown AAV5 vector-based diminution of the IL-1β transcript in vivo are warranted. PMID:21945742

Global effects of the CSR-1 RNA interference pathway on the transcriptional landscape.

PubMed

Cecere, Germano; Hoersch, Sebastian; O'Keeffe, Sean; Sachidanandam, Ravi; Grishok, Alla

2014-04-01

Argonaute proteins and their small RNA cofactors short interfering RNAs are known to inhibit gene expression at the transcriptional and post-transcriptional levels. In Caenorhabditis elegans, the Argonaute CSR-1 binds thousands of endogenous siRNAs (endo-siRNAs) that are antisense to germline transcripts. However, its role in gene expression regulation remains controversial. Here we used genome-wide profiling of nascent RNA transcripts and found that the CSR-1 RNA interference pathway promoted sense-oriented RNA polymerase II transcription. Moreover, a loss of CSR-1 function resulted in global increase in antisense transcription and ectopic transcription of silent chromatin domains, which led to reduced chromatin incorporation of centromere-specific histone H3. On the basis of these findings, we propose that the CSR-1 pathway helps maintain the directionality of active transcription, thereby propagating the distinction between transcriptionally active and silent genomic regions.

RNA-binding protein DUS16 plays an essential role in primary miRNA processing in the unicellular alga Chlamydomonas reinhardtii.

PubMed

Yamasaki, Tomohito; Onishi, Masayuki; Kim, Eun-Jeong; Cerutti, Heriberto; Ohama, Takeshi

2016-09-20

Canonical microRNAs (miRNAs) are embedded in duplexed stem-loops in long precursor transcripts and are excised by sequential cleavage by DICER nuclease(s). In this miRNA biogenesis pathway, dsRNA-binding proteins play important roles in animals and plants by assisting DICER. However, these RNA-binding proteins are poorly characterized in unicellular organisms. Here we report that a unique RNA-binding protein, Dull slicer-16 (DUS16), plays an essential role in processing of primary-miRNA (pri-miRNA) transcripts in the unicellular green alga Chlamydomonas reinhardtii In animals and plants, dsRNA-binding proteins involved in miRNA biogenesis harbor two or three dsRNA-binding domains (dsRBDs), whereas DUS16 contains one dsRBD and also an ssRNA-binding domain (RRM). The null mutant of DUS16 showed a drastic reduction in most miRNA species. Production of these miRNAs was complemented by expression of full-length DUS16, but the expression of RRM- or dsRBD-truncated DUS16 did not restore miRNA production. Furthermore, DUS16 is predominantly localized to the nucleus and associated with nascent (unspliced form) pri-miRNAs and the DICER-LIKE 3 protein. These results suggest that DUS16 recognizes pri-miRNA transcripts cotranscriptionally and promotes their processing into mature miRNAs as a component of a microprocessor complex. We propose that DUS16 is an essential factor for miRNA production in Chlamydomonas and, because DUS16 is functionally similar to the dsRNA-binding proteins involved in miRNA biogenesis in animals and land plants, our report provides insight into this mechanism in unicellular eukaryotes.

Functional organization of cytoplasmic inclusion bodies in cells infected by respiratory syncytial virus.

PubMed

Rincheval, Vincent; Lelek, Mickael; Gault, Elyanne; Bouillier, Camille; Sitterlin, Delphine; Blouquit-Laye, Sabine; Galloux, Marie; Zimmer, Christophe; Eleouet, Jean-François; Rameix-Welti, Marie-Anne

2017-09-15

Infection of cells by respiratory syncytial virus induces the formation of cytoplasmic inclusion bodies (IBs) where all the components of the viral RNA polymerase complex are concentrated. However, the exact organization and function of these IBs remain unclear. In this study, we use conventional and super-resolution imaging to dissect the internal structure of IBs. We observe that newly synthetized viral mRNA and the viral transcription anti-terminator M2-1 concentrate in IB sub-compartments, which we term "IB-associated granules" (IBAGs). In contrast, viral genomic RNA, the nucleoprotein, the L polymerase and its cofactor P are excluded from IBAGs. Live imaging reveals that IBAGs are highly dynamic structures. Our data show that IBs are the main site of viral RNA synthesis. They further suggest that shortly after synthesis in IBs, viral mRNAs and M2-1 transiently concentrate in IBAGs before reaching the cytosol and suggest a novel post-transcriptional function for M2-1.Respiratory syncytial virus (RSV) induces formation of inclusion bodies (IBs) sheltering viral RNA synthesis. Here, Rincheval et al. identify highly dynamic IB-associated granules (IBAGs) that accumulate newly synthetized viral mRNA and the viral M2-1 protein but exclude viral genomic RNA and RNA polymerase complexes.

Evidence that Poly(A) Binding Protein C1 Binds Nuclear Pre-mRNA Poly(A) Tails

PubMed Central

Hosoda, Nao; Lejeune, Fabrice; Maquat, Lynne E.

2006-01-01

In mammalian cells, poly(A) binding protein C1 (PABP C1) has well-known roles in mRNA translation and decay in the cytoplasm. However, PABPC1 also shuttles in and out of the nucleus, and its nuclear function is unknown. Here, we show that PABPC1, like the major nuclear poly(A) binding protein PABPN1, associates with nuclear pre-mRNAs that are polyadenylated and intron containing. PABPC1 does not bind nonpolyadenylated histone mRNA, indicating that the interaction of PABPC1 with pre-mRNA requires a poly(A) tail. Consistent with this conclusion, UV cross-linking results obtained using intact cells reveal that PABPC1 binds directly to pre-mRNA poly(A) tails in vivo. We also show that PABPC1 immunopurifies with poly(A) polymerase, suggesting that PABPC1 is acquired by polyadenylated transcripts during poly(A) tail synthesis. Our findings demonstrate that PABPC1 associates with polyadenylated transcripts earlier in mammalian mRNA biogenesis than previously thought and offer insights into the mechanism by which PABPC1 is recruited to newly synthesized poly(A). Our results are discussed in the context of pre-mRNA processing and stability and mRNA trafficking and the pioneer round of translation. PMID:16581783

Expression of metastasis-associated lung adenocarcinoma transcript 1 long non-coding RNA in vitro and in patients with non-small cell lung cancer.

PubMed

Lin, Ling; Li, Haiyan; Zhu, Yefei; He, Susu; Ge, Hongfei

2018-06-01

The present study aimed to investigate the association between the expression of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) long non-coding RNA (lncRNA) and the recurrence of non-small cell lung cancer (NSCLC) and to elucidate the potential mechanisms of MALAT1 in vitro . Between 1 June 1, 2010 and December 30, 2016, NSCLC tumor tissues and adjacent non-cancerous tissues were obtained from 120 patients with NSCLC, who had undergone surgical resection at Taizhou Hospital of Wenzhou Medical University (Linhai, China). The total RNA of tissues and cells were extracted and the expression of MALAT1 was determined using a wound healing assay and reverse transcription quantitative polymerase chain reaction. In addition, MALAT1 expression in A549 cells was silenced using small interfering RNA. The proliferation, migration and invasion of cells were then assessed using a CellTiter 96 kit and Transwell assays. MALAT1 expression was significantly increased in NSCLC samples compared with expression in adjacent non-cancerous tissues. Furthermore, the expression of MALAT1 in patients with NSCLC that exhibited recurrence was markedly higher than in those that did not. The results of the present study also demonstrated significant associations between high expression of MALAT1 and female sex, Tumor-Node-Metastasis advanced stage, vessel invasion, pathological differentiation and recurrence of patients with NSCLC. The proliferative, migratory and invasive abilities of MALAT1-silenced A549 cells were significantly decreased compared with those of control cells. MALAT1 expression was significantly increased in NSCLC tissues and was revealed to serve a role in the progression of NSCLC.

Long Non-coding RNA, PANDA, Contributes to the Stabilization of p53 Tumor Suppressor Protein.

PubMed

Kotake, Yojiro; Kitagawa, Kyoko; Ohhata, Tatsuya; Sakai, Satoshi; Uchida, Chiharu; Niida, Hiroyuki; Naemura, Madoka; Kitagawa, Masatoshi

2016-04-01

P21-associated noncoding RNA DNA damage-activated (PANDA) is induced in response to DNA damage and represses apoptosis by inhibiting the function of nuclear transcription factor Y subunit alpha (NF-YA) transcription factor. Herein, we report that PANDA affects regulation of p53 tumor-suppressor protein. U2OS cells were transfected with PANDA siRNAs. At 72 h post-transfection, cells were subjected to immunoblotting and quantitative reverse transcription-polymerase chain reaction. Depletion of PANDA was associated with decreased levels of p53 protein, but not p53 mRNA. The stability of p53 protein was markedly reduced by PANDA silencing. Degradation of p53 protein by silencing PANDA was prevented by treatment of MG132, a proteasome inhibitor. Moreover, depletion of PANDA prevented accumulation of p53 protein, as a result of DNA damage, induced by the genotoxic agent etoposide. These results suggest that PANDA stabilizes p53 protein in response to DNA damage, and provide new insight into the regulatory mechanisms of p53. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Stabilization and localization of Xist RNA are controlled by separate mechanisms and are not sufficient for X inactivation.

PubMed

Clemson, C M; Chow, J C; Brown, C J; Lawrence, J B

1998-07-13

These studies address whether XIST RNA is properly localized to the X chromosome in somatic cells where human XIST expression is reactivated, but fails to result in X inactivation (Tinker, A.V., and C.J. Brown. 1998. Nucl. Acids Res. 26:2935-2940). Despite a nuclear RNA accumulation of normal abundance and stability, XIST RNA does not localize in reactivants or in naturally inactive human X chromosomes in mouse/ human hybrid cells. The XIST transcripts are fully stabilized despite their inability to localize, and hence XIST RNA localization can be uncoupled from stabilization, indicating that these are separate steps controlled by distinct mechanisms. Mouse Xist RNA tightly localized to an active X chromosome, demonstrating for the first time that the active X chromosome in somatic cells is competent to associate with Xist RNA. These results imply that species-specific factors, present even in mature, somatic cells that do not normally express Xist, are necessary for localization. When Xist RNA is properly localized to an active mouse X chromosome, X inactivation does not result. Therefore, there is not a strict correlation between Xist localization and chromatin inactivation. Moreover, expression, stabilization, and localization of Xist RNA are not sufficient for X inactivation. We hypothesize that chromosomal association of XIST RNA may initiate subsequent developmental events required to enact transcriptional silencing.

The long non-coding RNA MALAT1 promotes the migration and invasion of hepatocellular carcinoma by sponging miR-204 and releasing SIRT1.

PubMed

Hou, Zhouhua; Xu, Xuwen; Zhou, Ledu; Fu, Xiaoyu; Tao, Shuhui; Zhou, Jiebin; Tan, Deming; Liu, Shuiping

2017-07-01

Increasing evidence supports the significance of long non-coding RNA in cancer development. Several recent studies suggest the oncogenic activity of long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in hepatocellular carcinoma. In this study, we explored the molecular mechanisms by which MALAT1 modulates hepatocellular carcinoma biological behaviors. We found that microRNA-204 was significantly downregulated in sh-MALAT1 HepG2 cell and 15 hepatocellular carcinoma tissues by quantitative real-time polymerase chain reaction analysis. Through bioinformatic screening, luciferase reporter assay, RNA-binding protein immunoprecipitation, and RNA pull-down assay, we identified microRNA-204 as a potential interacting partner for MALAT1. Functionally, wound-healing and transwell assays revealed that microRNA-204 significantly inhibited the migration and invasion of hepatocellular carcinoma cells. Notably, sirtuin 1 was recognized as a direct downstream target of microRNA-204 in HepG2 cells. Moreover, si-SIRT1 significantly inhibited cell invasion and migration process. These data elucidated, by sponging and competitive binding to microRNA-204, MALAT1 releases the suppression on sirtuin 1, which in turn promotes hepatocellular carcinoma migration and invasion. This study reveals a novel mechanism by which MALAT1 stimulates hepatocellular carcinoma progression and justifies targeting metastasis-associated lung adenocarcinoma transcript 1 as a potential therapy for hepatocellular carcinoma.

Autoregulatory mechanisms controlling the Microprocessor.

PubMed

Triboulet, Robinson; Gregory, Richard I

2010-01-01

The Microprocessor, comprising the ribonuclease Drosha and its essential cofactor, the double-stranded RNA-binding protein, DGCR8, is essential for the first step of the miRNA biogenesis pathway. It specifically cleaves double-stranded RNA within stem-loop structures of primary miRNA transcripts (pri-miRNAs) to generate precursor (pre-miRNA) intermediates. Pre-miRNAs are subsequently processed by Dicer to their mature 22 nt form. Thus, Microprocessor is essential for miRNA maturation, and pri-miRNA cleavage by this complex defines one end of the mature miRNA. Moreover, it is emerging that dysregulation of the Microprocessor is associated with various human diseases. It is therefore important to understand the mechanisms by which the expression of the subunits of the Microprocessor is regulated. Recent findings have uncovered a post-transcriptional mechanism that maintains the integrity of the Microprocessor. These studies revealed that the Microprocessor is involved in the processing of the messenger RNA (mRNA) that encodes DGCR8. This regulatory feedback loop, along with the reported role played by DGCR8 in the stabilization of Drosha protein, is part ofa newly identified regulatory mechanism controlling Microprocessor activity.

Microprocessor activity controls differential miRNA biogenesis In Vivo.

PubMed

Conrad, Thomas; Marsico, Annalisa; Gehre, Maja; Orom, Ulf Andersson

2014-10-23

In miRNA biogenesis, pri-miRNA transcripts are converted into pre-miRNA hairpins. The in vivo properties of this process remain enigmatic. Here, we determine in vivo transcriptome-wide pri-miRNA processing using next-generation sequencing of chromatin-associated pri-miRNAs. We identify a distinctive Microprocessor signature in the transcriptome profile from which efficiency of the endogenous processing event can be accurately quantified. This analysis reveals differential susceptibility to Microprocessor cleavage as a key regulatory step in miRNA biogenesis. Processing is highly variable among pri-miRNAs and a better predictor of miRNA abundance than primary transcription itself. Processing is also largely stable across three cell lines, suggesting a major contribution of sequence determinants. On the basis of differential processing efficiencies, we define functionality for short sequence features adjacent to the pre-miRNA hairpin. In conclusion, we identify Microprocessor as the main hub for diversified miRNA output and suggest a role for uncoupling miRNA biogenesis from host gene expression. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Post-transcriptional inducible gene regulation by natural antisense RNA.

PubMed

Nishizawa, Mikio; Ikeya, Yukinobu; Okumura, Tadayoshi; Kimura, Tominori

2015-01-01

Accumulating data indicate the existence of natural antisense transcripts (asRNAs), frequently transcribed from eukaryotic genes and do not encode proteins in many cases. However, their importance has been overlooked due to their heterogeneity, low expression level, and unknown function. Genes induced in responses to various stimuli are transcriptionally regulated by the activation of a gene promoter and post-transcriptionally regulated by controlling mRNA stability and translatability. A low-copy-number asRNA may post-transcriptionally regulate gene expression with cis-controlling elements on the mRNA. The asRNA itself may act as regulatory RNA in concert with trans-acting factors, including various RNA-binding proteins that bind to cis-controlling elements, microRNAs, and drugs. A novel mechanism that regulates mRNA stability includes the interaction of asRNA with mRNA by hybridization to loops in secondary structures. Furthermore, recent studies have shown that the functional network of mRNAs, asRNAs, and microRNAs finely tunes the levels of mRNA expression. The post-transcriptional mechanisms via these RNA-RNA interactions may play pivotal roles to regulate inducible gene expression and present the possibility of the involvement of asRNAs in various diseases.

Cortical Gene Expression After a Conditional Knockout of 67 kDa Glutamic Acid Decarboxylase in Parvalbumin Neurons.

PubMed

Georgiev, Danko; Yoshihara, Toru; Kawabata, Rika; Matsubara, Takurou; Tsubomoto, Makoto; Minabe, Yoshio; Lewis, David A; Hashimoto, Takanori

2016-07-01

In the cortex of subjects with schizophrenia, expression of glutamic acid decarboxylase 67 (GAD67), the enzyme primarily responsible for cortical GABA synthesis, is reduced in the subset of GABA neurons that express parvalbumin (PV). This GAD67 deficit is accompanied by lower cortical levels of other GABA-associated transcripts, including GABA transporter-1, PV, brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B, somatostatin, GABAA receptor α1 subunit, and KCNS3 potassium channel subunit mRNAs. In contrast, messenger RNA (mRNA) levels for glutamic acid decarboxylase 65 (GAD65), another enzyme for GABA synthesis, are not altered. We tested the hypothesis that this pattern of GABA-associated transcript levels is secondary to the GAD67 deficit in PV neurons by analyzing cortical levels of these GABA-associated mRNAs in mice with a PV neuron-specific GAD67 knockout. Using in situ hybridization, we found that none of the examined GABA-associated transcripts had lower cortical expression in the knockout mice. In contrast, PV, BDNF, KCNS3, and GAD65 mRNA levels were higher in the homozygous mice. In addition, our behavioral test battery failed to detect a change in sensorimotor gating or working memory, although the homozygous mice exhibited increased spontaneous activities. These findings suggest that reduced GAD67 expression in PV neurons is not an upstream cause of the lower levels of GABA-associated transcripts, or of the characteristic behaviors, in schizophrenia. In PV neuron-specific GAD67 knockout mice, increased levels of PV, BDNF, and KCNS3 mRNAs might be the consequence of increased neuronal activity secondary to lower GABA synthesis, whereas increased GAD65 mRNA might represent a compensatory response to increase GABA synthesis. © The Author 2016. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Cigarette Smoking Decreases Global MicroRNA Expression in Human Alveolar Macrophages

PubMed Central

Graff, Joel W.; Powers, Linda S.; Dickson, Anne M.; Kim, Jongkwang; Reisetter, Anna C.; Hassan, Ihab H.; Kremens, Karol; Gross, Thomas J.

2012-01-01

Human alveolar macrophages are critical components of the innate immune system. Cigarette smoking-induced changes in alveolar macrophage gene expression are linked to reduced resistance to pulmonary infections and to the development of emphysema/COPD. We hypothesized that microRNAs (miRNAs) could control, in part, the unique messenger RNA (mRNA) expression profiles found in alveolar macrophages of cigarette smokers. Activation of macrophages with different stimuli in vitro leads to a diverse range of M1 (inflammatory) and M2 (anti-inflammatory) polarized phenotypes that are thought to mimic activated macrophages in distinct tissue environments. Microarray mRNA data indicated that smoking promoted an “inverse” M1 mRNA expression program, defined by decreased expression of M1-induced transcripts and increased expression of M1-repressed transcripts with few changes in M2-regulated transcripts. RT-PCR arrays identified altered expression of many miRNAs in alveolar macrophages of smokers and a decrease in global miRNA abundance. Stratification of human subjects suggested that the magnitude of the global decrease in miRNA abundance was associated with smoking history. We found that many of the miRNAs with reduced expression in alveolar macrophages of smokers were predicted to target mRNAs upregulated in alveolar macrophages of smokers. For example, miR-452 is predicted to target the transcript encoding MMP12, an important effector of smoking-related diseases. Experimental antagonism of miR-452 in differentiated monocytic cells resulted in increased expression of MMP12. The comprehensive mRNA and miRNA expression profiles described here provide insight into gene expression regulation that may underlie the adverse effects cigarette smoking has on alveolar macrophages. PMID:22952876

Establishment of an in vitro transcription system for Peste des petits ruminant virus.

PubMed

Yunus, Mohammad; Shaila, Melkote S

2012-12-05

Peste-des-petits ruminants virus (PPRV) is a non segmented negative strand RNA virus of the genus Morbillivirus within Paramyxoviridae family. Negative strand RNA viruses are known to carry nucleocapsid (N) protein, phospho (P) protein and RNA polymerase (L protein) packaged within the virion which possess all activities required for transcription, post-transcriptional modification of mRNA and replication. In order to understand the mechanism of transcription and replication of the virus, an in vitro transcription reconstitution system is required. In the present work, an in vitro transcription system has been developed with ribonucleoprotein (RNP) complex purified from virus infected cells as well as partially purified recombinant polymerase (L-P) complex from insect cells along with N-RNA (genomic RNA encapsidated by N protein) template isolated from virus infected cells. RNP complex isolated from virus infected cells and recombinant L-P complex purified from insect cells was used to reconstitute transcription on N-RNA template. The requirement for this transcription reconstitution has been defined. Transcription of viral genes in the in vitro system was confirmed by PCR amplification of cDNAs corresponding to individual transcripts using gene specific primers. In order to measure the relative expression level of viral transcripts, real time PCR analysis was carried out. qPCR analysis of the transcription products made in vitro showed a gradient of polarity of transcription from 3' end to 5' end of the genome similar to that exhibited by the virus in infected cells. This report describes for the first time, the development of an in vitro transcription reconstitution system for PPRV with RNP complex purified from infected cells and recombinant L-P complex expressed in insect cells. Both the complexes were able to synthesize all the mRNA species in vitro, exhibiting a gradient of polarity in transcription.

A case of cervical cancer expressed three mRNA variant of Hyaluronan-mediated motility receptor

PubMed Central

Villegas-Ruíz, Vanessa; Salcedo, Mauricio; Zentella-Dehesa, Alejandro; de Oca, Edén V Montes; Román-Basaure, Edgar; Mantilla-Morales, Alejandra; Dávila-Borja, Víctor M; Juárez-Méndez, Sergio

2014-01-01

Cervical cancer is the second malignancy in Mexico, little is known about the prognostic factors associated with this disease. Several cellular components are important in their transformation and progression. Alternative mRNA splice is an important mechanism for generating protein diversity, nevertheless, in cancer unknown mRNA diversity is expressed. Hyaluronan-mediated motility receptor (HMMR, RHAMM, CD168) is a family member of proteins, hyaluronan acid dependent, and has been associated with different malignant processes such as: angiogenesis, cell invasiveness, proliferation, metastasis and poor outcome in some tumors. In the present study we identified expression of HMMR in cervical cancer by means of RT-PCR and sequencing. Our results indicate co-expression of two HMMR variants in all samples, and one case expressed three alternative HMMR splice transcripts. These results showed the heterogeneity of mRNA transcripts of HMMR that could express in cancer and the expression of HMMR could be marker of malignancy in CC. PMID:24966934

Uncovering transcription factor and microRNA risk regulatory pathways associated with osteoarthritis by network analysis.

PubMed

Song, Zhenhua; Zhang, Chi; He, Lingxiao; Sui, Yanfang; Lin, Xiafei; Pan, Jingjing

2018-06-12

Osteoarthritis (OA) is the most common form of joint disease. The development of inflammation have been considered to play a key role during the progression of OA. Regulatory pathways are known to play crucial roles in many pathogenic processes. Thus, deciphering these risk regulatory pathways is critical for elucidating the mechanisms underlying OA. We constructed an OA-specific regulatory network by integrating comprehensive curated transcription and post-transcriptional resource involving transcription factor (TF) and microRNA (miRNA). To deepen our understanding of underlying molecular mechanisms of OA, we developed an integrated systems approach to identify OA-specific risk regulatory pathways. In this study, we identified 89 significantly differentially expressed genes between normal and inflamed areas of OA patients. We found the OA-specific regulatory network was a standard scale-free network with small-world properties. It significant enriched many immune response-related functions including leukocyte differentiation, myeloid differentiation and T cell activation. Finally, 141 risk regulatory pathways were identified based on OA-specific regulatory network, which contains some known regulator of OA. The risk regulatory pathways may provide clues for the etiology of OA and be a potential resource for the discovery of novel OA-associated disease genes. Copyright © 2018 Elsevier Inc. All rights reserved.

RNA-Skim: a rapid method for RNA-Seq quantification at transcript level

PubMed Central

Zhang, Zhaojun; Wang, Wei

2014-01-01

Motivation: RNA-Seq technique has been demonstrated as a revolutionary means for exploring transcriptome because it provides deep coverage and base pair-level resolution. RNA-Seq quantification is proven to be an efficient alternative to Microarray technique in gene expression study, and it is a critical component in RNA-Seq differential expression analysis. Most existing RNA-Seq quantification tools require the alignments of fragments to either a genome or a transcriptome, entailing a time-consuming and intricate alignment step. To improve the performance of RNA-Seq quantification, an alignment-free method, Sailfish, has been recently proposed to quantify transcript abundances using all k-mers in the transcriptome, demonstrating the feasibility of designing an efficient alignment-free method for transcriptome quantification. Even though Sailfish is substantially faster than alternative alignment-dependent methods such as Cufflinks, using all k-mers in the transcriptome quantification impedes the scalability of the method. Results: We propose a novel RNA-Seq quantification method, RNA-Skim, which partitions the transcriptome into disjoint transcript clusters based on sequence similarity, and introduces the notion of sig-mers, which are a special type of k-mers uniquely associated with each cluster. We demonstrate that the sig-mer counts within a cluster are sufficient for estimating transcript abundances with accuracy comparable with any state-of-the-art method. This enables RNA-Skim to perform transcript quantification on each cluster independently, reducing a complex optimization problem into smaller optimization tasks that can be run in parallel. As a result, RNA-Skim uses <4% of the k-mers and <10% of the CPU time required by Sailfish. It is able to finish transcriptome quantification in <10 min per sample by using just a single thread on a commodity computer, which represents >100 speedup over the state-of-the-art alignment-based methods, while delivering comparable or higher accuracy. Availability and implementation: The software is available at http://www.csbio.unc.edu/rs. Contact: weiwang@cs.ucla.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:24931995

Super-enhancer-mediated RNA processing revealed by integrative microRNA network analysis

PubMed Central

Suzuki, Hiroshi I.; Young, Richard A; Sharp, Phillip A

2017-01-01

Summary Super-enhancers are an emerging sub-class of regulatory regions controlling cell identity and disease genes. However, their biological function and impact on miRNA networks are unclear. Here we report that super-enhancers drive the biogenesis of master miRNAs crucial for cell identity by enhancing both transcription and Drosha/DGCR8-mediated primary miRNA (pri-miRNA) processing. Super-enhancers, together with broad H3K4me3 domains, shape a tissue-specific and evolutionarily conserved atlas of miRNA expression and function. CRISPR/Cas9 genomics revealed that super-enhancer constituents act cooperatively and facilitate Drosha/DGCR8 recruitment and pri-miRNA processing to boost cell-specific miRNA production. The BET-bromodomain inhibitor JQ1 preferentially inhibits super-enhancer-directed cotranscriptional pri-miRNA processing. Furthermore, super-enhancers are characterized by pervasive interaction with DGCR8/Drosha and DGCR8/Drosha-regulated mRNA stability control, suggesting unique RNA regulation at super-enhancers. Finally, super-enhancers mark multiple miRNAs associated with cancer hallmarks. This study presents principles underlying miRNA biology in health and disease and a unrecognized higher-order property of super-enhancers in RNA processing beyond transcription. PMID:28283057

RNA editing with CRISPR-Cas13.

PubMed

Cox, David B T; Gootenberg, Jonathan S; Abudayyeh, Omar O; Franklin, Brian; Kellner, Max J; Joung, Julia; Zhang, Feng

2017-11-24

Nucleic acid editing holds promise for treating genetic disease, particularly at the RNA level, where disease-relevant sequences can be rescued to yield functional protein products. Type VI CRISPR-Cas systems contain the programmable single-effector RNA-guided ribonuclease Cas13. We profiled type VI systems in order to engineer a Cas13 ortholog capable of robust knockdown and demonstrated RNA editing by using catalytically inactive Cas13 (dCas13) to direct adenosine-to-inosine deaminase activity by ADAR2 (adenosine deaminase acting on RNA type 2) to transcripts in mammalian cells. This system, referred to as RNA Editing for Programmable A to I Replacement (REPAIR), which has no strict sequence constraints, can be used to edit full-length transcripts containing pathogenic mutations. We further engineered this system to create a high-specificity variant and minimized the system to facilitate viral delivery. REPAIR presents a promising RNA-editing platform with broad applicability for research, therapeutics, and biotechnology. Copyright © 2017, American Association for the Advancement of Science.

Attenuation of the suppressive activity of cellular splicing factor SRSF3 by Kaposi sarcoma-associated herpesvirus ORF57 protein is required for RNA splicing.

PubMed

Majerciak, Vladimir; Lu, Mathew; Li, Xiaofan; Zheng, Zhi-Ming

2014-11-01

Kaposi sarcoma-associated herpesvirus (KSHV) ORF57 is a multifunctional post-transcriptional regulator essential for viral gene expression during KSHV lytic infection. ORF57 requires interactions with various cellular proteins for its function. Here, we identified serine/arginine-rich splicing factor 3 (SRSF3, formerly known as SRp20) as a cellular cofactor involved in ORF57-mediated splicing of KSHV K8β RNA. In the absence of ORF57, SRSF3 binds to a suboptimal K8β intron and inhibits K8β splicing. Knockdown of SRSF3 promotes K8β splicing, mimicking the effect of ORF57. The N-terminal half of ORF57 binds to the RNA recognition motif of SRSF3, which prevents SRSF3 from associating with the K8β intron RNA and therefore attenuates the suppressive effect of SRSF3 on K8β splicing. ORF57 also promotes splicing of heterologous non-KSHV transcripts that are negatively regulated by SRSF3, indicating that the effect of ORF57 on SRSF3 activity is independent of RNA target. SPEN proteins, previously identified as ORF57-interacting partners, suppress ORF57 splicing activity by displacing ORF57 from SRSF3-RNA complexes. In summary, we have identified modulation of SRSF3 activity as the molecular mechanism by which ORF57 promotes RNA splicing. Published by Cold Spring Harbor Laboratory Press for the RNA Society.

Quick Fluorescent In Situ Hybridization Protocol for Xist RNA Combined with Immunofluorescence of Histone Modification in X-chromosome Inactivation

PubMed Central

Yamada, Norishige; Ogawa, Akiyo; Ogawa, Yuya

2014-01-01

Combining RNA fluorescent in situ hybridization (FISH) with immunofluorescence (immuno-FISH) creates a technique that can be employed at the single cell level to detect the spatial dynamics of RNA localization with simultaneous insight into the localization of proteins, epigenetic modifications and other details which can be highlighted by immunofluorescence. X-chromosome inactivation is a paradigm for long non-coding RNA (lncRNA)-mediated gene silencing. X-inactive specific transcript (Xist) lncRNA accumulation (called an Xist cloud) on one of the two X-chromosomes in mammalian females is a critical step to initiate X-chromosome inactivation. Xist RNA directly or indirectly interacts with various chromatin-modifying enzymes and introduces distinct epigenetic landscapes to the inactive X-chromosome (Xi). One known epigenetic hallmark of the Xi is the Histone H3 trimethyl-lysine 27 (H3K27me3) modification. Here, we describe a simple and quick immuno-FISH protocol for detecting Xist RNA using RNA FISH with multiple oligonucleotide probes coupled with immunofluorescence of H3K27me3 to examine the localization of Xist RNA and associated epigenetic modifications. Using oligonucleotide probes results in a shorter incubation time and more sensitive detection of Xist RNA compared to in vitro transcribed RNA probes (riboprobes). This protocol provides a powerful tool for understanding the dynamics of lncRNAs and its associated epigenetic modification, chromatin structure, nuclear organization and transcriptional regulation. PMID:25489864

Molecular mechanisms of long noncoding RNAs on gastric cancer

PubMed Central

Li, Tianwen; Mo, Xiaoyan; Fu, Liyun; Xiao, Bingxiu; Guo, Junming

2016-01-01

Long noncoding RNAs (lncRNAs) are non-protein coding transcripts longer than 200 nucleotides. Aberrant expression of lncRNAs has been found associated with gastric cancer, one of the most malignant tumors. By complementary base pairing with mRNAs or forming complexes with RNA binding proteins (RBPs), some lncRNAs including GHET1, MALAT1, and TINCR may mediate mRNA stability and splicing. Other lncRNAs, such as BC032469, GAPLINC, and HOTAIR, participate in the competing endogenous RNA (ceRNA) network. Under certain circumstances, ANRIL, GACAT3, H19, MEG3, and TUSC7 exhibit their biological roles by associating with microRNAs (miRNAs). By recruiting histone-modifying complexes, ANRIL, FENDRR, H19, HOTAIR, MALAT1, and PVT1 may inhibit the transcription of target genes in cis or trans. Through these mechanisms, lncRNAs form RNA-dsDNA triplex. CCAT1, GAPLINC, GAS5, H19, MEG3, and TUSC7 play oncogenic or tumor suppressor roles by correlated with tumor suppressor P53 or onco-protein c-Myc, respectively. In conclusion, interaction with DNA, RNA and proteins is involved in lncRNAs’ participation in gastric tumorigenesis and development. PMID:26788991

Ki-67 protein is associated with ribosomal RNA transcription in quiescent and proliferating cells.

PubMed

Bullwinkel, Jörn; Baron-Lühr, Bettina; Lüdemann, Anja; Wohlenberg, Claudia; Gerdes, Johannes; Scholzen, Thomas

2006-03-01

The nuclear Ki-67 protein (pKi-67) has previously been shown to be exclusively expressed in proliferating cells. As a result, antibodies against this protein are widely used as prognostic tools in cancer diagnostics. Here we show, that despite the strong downregulation of pKi-67 expression in non-proliferating cells, the protein can nevertheless be detected at sites linked to ribosomal RNA (rRNA) synthesis. Although this finding does not argue against the use of pKi-67 as a proliferation marker, it has wide ranging implications for the elucidation of pKi-67 function. Employing the novel antibody TuBB-9, we could further demonstrate that also in proliferating cells, a fraction of pKi-67 is found at sites linked to the rRNA transcription machinery during interphase and mitosis. Moreover, chromatin immunoprecipitation (ChIP) assays provided evidence for a physical association of pKi-67 with chromatin of the promoter and transcribed region of the rRNA gene cluster. These data strongly suggest a role for pKi-67 in the early steps of rRNA synthesis. Copyright 2005 Wiley-Liss, Inc.

Identification of human Phosphatidyl Inositol 5-Phosphate 4-Kinase as an RNA binding protein that is imported into Plasmodium falciparum.

PubMed

Vindu, Arya; Dandewad, Vishal; Seshadri, Vasudevan

2018-04-06

Plasmodium falciparum is a causative agent for malaria and has a complex life cycle in human and mosquito hosts. Translation repression of specific set of mRNA has been reported in gametocyte stages of this parasite. A conserved element present in the 3'UTR of some of these transcripts was identified. Biochemical studies have identified components of the RNA storage and/or translation inhibitor complex but it is not yet clear how the complex is specifically recruited on the RNA targeted for translation regulation. We used the 3'UTR region of translationally regulated transcripts to identify Phosphatidyl-inositol 5-phosphate 4-kinase (PIP4K2A) as the protein that associates with these RNAs. We further show that recombinant PIP4K2A has the RNA binding activity and can associate specifically with Plasmodium 3'UTR RNAs. Immunostainings show that hPIP4K2A is imported into the Plasmodium parasite from RBC. These results identify a novel RNA binding role for PIP4K2A that may play a role in Plasmodium propagation. Copyright © 2018 Elsevier Inc. All rights reserved.

Post-Transcriptional Regulation of Endothelial Nitric Oxide Synthase Expression by Polypyrimidine Tract-Binding Protein 1.

PubMed

Yi, Bing; Ozerova, Maria; Zhang, Guan-Xin; Yan, Guijun; Huang, Shengdong; Sun, Jianxin

2015-10-01

Endothelial nitric oxide synthase (eNOS) is an important regulator of vascular function and its expression is regulated at post-transcriptional levels through a yet unknown mechanism. The purpose of this study is to elucidate the post-transcriptional factors regulating eNOS expression and function in endothelium. To elucidate the molecular basis of tumor necrosis factor (TNF)-α-mediated eNOS mRNA instability, biotinylated eNOS 3'-untranslational region (UTR) was used to purify its associated proteins by RNA affinity chromatography from cytosolic fractions of TNF-α-stimulated human umbilical vein endothelial cells (HUVECs). We identified 2 cytosolic proteins, with molecular weight of 52 and 57 kDa, which specifically bind to eNOS 3'-UTR in response to TNF-α stimulation. Matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis identified the 57-kDa protein as polypyrimidine tract-binding protein 1 (PTB1). RNA gel mobility shift and UV cross-linking assays demonstrated that PTB1 binds to a UCUU-rich sequence in eNOS 3'-UTR, and the C-terminal half of PTB1 is critical to this interaction. Importantly, PTB1 overexpression leads to decreased activity of luciferase gene fused with eNOS 3'-UTR as well as reduced eNOS expression and activity in human ECs. In HUVECs, we show that TNF-α markedly increased PTB1 expression, whereas adenovirus-mediated PTB1 overexpression decreased eNOS mRNA stability and reduced protein expression and endothelium-dependent relaxation. Furthermore, knockdown of PTB1 substantially attenuated TNF-α-induced destabilization of eNOS transcript and downregulation of eNOS expression. These results indicate that PTB1 is essential for regulating eNOS expression at post-transcriptional levels and suggest a novel therapeutic target for treatment of vascular diseases associated with inflammatory endothelial dysfunction. © 2015 American Heart Association, Inc.

Correlated mRNAs and miRNAs from co-expression and regulatory networks affect porcine muscle and finally meat properties.

PubMed

Ponsuksili, Siriluck; Du, Yang; Hadlich, Frieder; Siengdee, Puntita; Murani, Eduard; Schwerin, Manfred; Wimmers, Klaus

2013-08-05

Physiological processes aiding the conversion of muscle to meat involve many genes associated with muscle structure and metabolic processes. MicroRNAs regulate networks of genes to orchestrate cellular functions, in turn regulating phenotypes. We applied weighted gene co-expression network analysis to identify co-expression modules that correlated to meat quality phenotypes and were highly enriched for genes involved in glucose metabolism, response to wounding, mitochondrial ribosome, mitochondrion, and extracellular matrix. Negative correlation of miRNA with mRNA and target prediction were used to select transcripts out of the modules of trait-associated mRNAs to further identify those genes that are correlated with post mortem traits. Porcine muscle co-expression transcript networks that correlated to post mortem traits were identified. The integration of miRNA and mRNA expression analyses, as well as network analysis, enabled us to interpret the differentially-regulated genes from a systems perspective. Linking co-expression networks of transcripts and hierarchically organized pairs of miRNAs and mRNAs to meat properties yields new insight into several biological pathways underlying phenotype differences. These pathways may also be diagnostic for many myopathies, which are accompanied by deficient nutrient and oxygen supply of muscle fibers.

Differences in transcript abundance of genes on BTA15 located within a region associated with gain in beef steers

USDA-ARS?s Scientific Manuscript database

Six markers on the Illumina Bovine 50k BeadChip within a 229 Kb region on bovine chromosome 15 were associated (P=0.002) with average daily gain (ADG) in beef cattle. We chose to evaluate seven genes located within this region for variation in RNA transcript abundance in a library of tissue samples ...

RNA polymerase I transcription in a Brassica interspecific hybrid and its progenitors: Tests of transcription factor involvement in nucleolar dominance.

PubMed Central

Frieman, M; Chen, Z J; Saez-Vasquez, J; Shen, L A; Pikaard, C S

1999-01-01

In interspecific hybrids or allopolyploids, often one parental set of ribosomal RNA genes is transcribed and the other is silent, an epigenetic phenomenon known as nucleolar dominance. Silencing is enforced by cytosine methylation and histone deacetylation, but the initial discrimination mechanism is unknown. One hypothesis is that a species-specific transcription factor is inactivated, thereby silencing one set of rRNA genes. Another is that dominant rRNA genes have higher binding affinities for limiting transcription factors. A third suggests that selective methylation of underdominant rRNA genes blocks transcription factor binding. We tested these hypotheses using Brassica napus (canola), an allotetraploid derived from B. rapa and B. oleracea in which only B. rapa rRNA genes are transcribed. B. oleracea and B. rapa rRNA genes were active when transfected into protoplasts of the other species, which argues against the species-specific transcription factor model. B. oleracea and B. rapa rRNA genes also competed equally for the pol I transcription machinery in vitro and in vivo. Cytosine methylation had no effect on rRNA gene transcription in vitro, which suggests that transcription factor binding was unimpaired. These data are inconsistent with the prevailing models and point to discrimination mechanisms that are likely to act at a chromosomal level. PMID:10224274

Simian Virus 40 Large T Antigen Interacts with Human TFIIB-Related Factor and Small Nuclear RNA-Activating Protein Complex for Transcriptional Activation of TATA-Containing Polymerase III Promoters

PubMed Central

Damania, Blossom; Mital, Renu; Alwine, James C.

1998-01-01

The TATA-binding protein (TBP) is common to the basal transcription factors of all three RNA polymerases, being associated with polymerase-specific TBP-associated factors (TAFs). Simian virus 40 large T antigen has previously been shown to interact with the TBP-TAFII complexes, TFIID (B. Damania and J. C. Alwine, Genes Dev. 10:1369–1381, 1996), and the TBP-TAFI complex, SL1 (W. Zhai, J. Tuan, and L. Comai, Genes Dev. 11:1605–1617, 1997), and in both cases these interactions are critical for transcriptional activation. We show a similar mechanism for activation of the class 3 polymerase III (pol III) promoter for the U6 RNA gene. Large T antigen can activate this promoter, which contains a TATA box and an upstream proximal sequence element but cannot activate the TATA-less, intragenic VAI promoter (a class 2, pol III promoter). Mutants of large T antigen that cannot activate pol II promoters also fail to activate the U6 promoter. We provide evidence that large T antigen can interact with the TBP-containing pol III transcription factor human TFIIB-related factor (hBRF), as well as with at least two of the three TAFs in the pol III-specific small nuclear RNA-activating protein complex (SNAPc). In addition, we demonstrate that large T antigen can cofractionate and coimmunoprecipitate with the hBRF-containing complex TFIIIB derived from HeLa cells infected with a recombinant adenovirus which expresses large T antigen. Hence, similar to its function with pol I and pol II promoters, large T antigen interacts with TBP-containing, basal pol III transcription factors and appears to perform a TAF-like function. PMID:9488448

Transcriptional Profiling of Synovial Macrophages Using Minimally Invasive Ultrasound-Guided Synovial Biopsies in Rheumatoid Arthritis.

PubMed

Mandelin, Arthur M; Homan, Philip J; Shaffer, Alexander M; Cuda, Carla M; Dominguez, Salina T; Bacalao, Emily; Carns, Mary; Hinchcliff, Monique; Lee, Jungwha; Aren, Kathleen; Thakrar, Anjali; Montgomery, Anna B; Bridges, S Louis; Bathon, Joan M; Atkinson, John P; Fox, David A; Matteson, Eric L; Buckley, Christopher D; Pitzalis, Costantino; Parks, Deborah; Hughes, Laura B; Geraldino-Pardilla, Laura; Ike, Robert; Phillips, Kristine; Wright, Kerry; Filer, Andrew; Kelly, Stephen; Ruderman, Eric M; Morgan, Vince; Abdala-Valencia, Hiam; Misharin, Alexander V; Budinger, G Scott; Bartom, Elizabeth T; Pope, Richard M; Perlman, Harris; Winter, Deborah R

2018-06-01

Currently, there are no reliable biomarkers for predicting therapeutic response in patients with rheumatoid arthritis (RA). The synovium may unlock critical information for determining efficacy, since a reduction in the numbers of sublining synovial macrophages remains the most reproducible biomarker. Thus, a clinically actionable method for the collection of synovial tissue, which can be analyzed using high-throughput strategies, must become a reality. This study was undertaken to assess the feasibility of utilizing synovial biopsies as a precision medicine-based approach for patients with RA. Rheumatologists at 6 US academic sites were trained in minimally invasive ultrasound-guided synovial tissue biopsy. Biopsy specimens obtained from patients with RA and synovial tissue from patients with osteoarthritis (OA) were subjected to histologic analysis, fluorescence-activated cell sorting, and RNA sequencing (RNA-seq). An optimized protocol for digesting synovial tissue was developed to generate high-quality RNA-seq libraries from isolated macrophage populations. Associations were determined between macrophage transcriptional profiles and clinical parameters in RA patients. Patients with RA reported minimal adverse effects in response to synovial biopsy. Comparable RNA quality was observed from synovial tissue and isolated macrophages between patients with RA and patients with OA. Whole tissue samples from patients with RA demonstrated a high degree of transcriptional heterogeneity. In contrast, the transcriptional profile of isolated RA synovial macrophages highlighted different subpopulations of patients and identified 6 novel transcriptional modules that were associated with disease activity and therapy. Performance of synovial tissue biopsies by rheumatologists in the US is feasible and generates high-quality samples for research. Through the use of cutting-edge technologies to analyze synovial biopsy specimens in conjunction with corresponding clinical information, a precision medicine-based approach for patients with RA is attainable. © 2018, American College of Rheumatology.

MINCR is a MYC-induced lncRNA able to modulate MYC's transcriptional network in Burkitt lymphoma cells.

PubMed

Doose, Gero; Haake, Andrea; Bernhart, Stephan H; López, Cristina; Duggimpudi, Sujitha; Wojciech, Franziska; Bergmann, Anke K; Borkhardt, Arndt; Burkhardt, Birgit; Claviez, Alexander; Dimitrova, Lora; Haas, Siegfried; Hoell, Jessica I; Hummel, Michael; Karsch, Dennis; Klapper, Wolfram; Kleo, Karsten; Kretzmer, Helene; Kreuz, Markus; Küppers, Ralf; Lawerenz, Chris; Lenze, Dido; Loeffler, Markus; Mantovani-Löffler, Luisa; Möller, Peter; Ott, German; Richter, Julia; Rohde, Marius; Rosenstiel, Philip; Rosenwald, Andreas; Schilhabel, Markus; Schneider, Markus; Scholz, Ingrid; Stilgenbauer, Stephan; Stunnenberg, Hendrik G; Szczepanowski, Monika; Trümper, Lorenz; Weniger, Marc A; Hoffmann, Steve; Siebert, Reiner; Iaccarino, Ingram

2015-09-22

Despite the established role of the transcription factor MYC in cancer, little is known about the impact of a new class of transcriptional regulators, the long noncoding RNAs (lncRNAs), on MYC ability to influence the cellular transcriptome. Here, we have intersected RNA-sequencing data from two MYC-inducible cell lines and a cohort of 91 B-cell lymphomas with or without genetic variants resulting in MYC overexpression. We identified 13 lncRNAs differentially expressed in IG-MYC-positive Burkitt lymphoma and regulated in the same direction by MYC in the model cell lines. Among them, we focused on a lncRNA that we named MYC-induced long noncoding RNA (MINCR), showing a strong correlation with MYC expression in MYC-positive lymphomas. To understand its cellular role, we performed RNAi and found that MINCR knockdown is associated with an impairment in cell cycle progression. Differential gene expression analysis after RNAi showed a significant enrichment of cell cycle genes among the genes down-regulated after MINCR knockdown. Interestingly, these genes are enriched in MYC binding sites in their promoters, suggesting that MINCR acts as a modulator of the MYC transcriptional program. Accordingly, MINCR knockdown was associated with a reduction in MYC binding to the promoters of selected cell cycle genes. Finally, we show that down-regulation of Aurora kinases A and B and chromatin licensing and DNA replication factor 1 may explain the reduction in cellular proliferation observed on MINCR knockdown. We, therefore, suggest that MINCR is a newly identified player in the MYC transcriptional network able to control the expression of cell cycle genes.

Altered minor-groove hydrogen bonds in DNA block transcription elongation by T7 RNA polymerase.

PubMed

Tanasova, Marina; Goeldi, Silvan; Meyer, Fabian; Hanawalt, Philip C; Spivak, Graciela; Sturla, Shana J

2015-05-26

DNA transcription depends upon the highly efficient and selective function of RNA polymerases (RNAPs). Modifications in the template DNA can impact the progression of RNA synthesis, and a number of DNA adducts, as well as abasic sites, arrest or stall transcription. Nonetheless, data are needed to understand why certain modifications to the structure of DNA bases stall RNA polymerases while others are efficiently bypassed. In this study, we evaluate the impact that alterations in dNTP/rNTP base-pair geometry have on transcription. T7 RNA polymerase was used to study transcription over modified purines and pyrimidines with altered H-bonding capacities. The results suggest that introducing wobble base-pairs into the DNA:RNA heteroduplex interferes with transcriptional elongation and stalls RNA polymerase. However, transcriptional stalling is not observed if mismatched base-pairs do not H-bond. Together, these studies show that RNAP is able to discriminate mismatches resulting in wobble base-pairs, and suggest that, in cases of modifications with minor steric impact, DNA:RNA heteroduplex geometry could serve as a controlling factor for initiating transcription-coupled DNA repair. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bacillus subtilis δ Factor Functions as a Transcriptional Regulator by Facilitating the Open Complex Formation.

PubMed

Prajapati, Ranjit Kumar; Sengupta, Shreya; Rudra, Paulami; Mukhopadhyay, Jayanta

2016-01-15

Most bacterial RNA polymerases (RNAP) contain five conserved subunits, viz. 2α, β, β', and ω. However, in many Gram-positive bacteria, especially in fermicutes, RNAP is associated with an additional factor, called δ. For over three decades since its identification, it had been thought that δ functioned as a subunit of RNAP to enhance the level of transcripts by recycling RNAP. In support of the previous observations, we also find that δ is involved in recycling of RNAP by releasing the RNA from the ternary complex. We further show that δ binds to RNA and is able to recycle RNAP when the length of the nascent RNA reaches a critical length. However, in this work we decipher a new function of δ. Performing biochemical and mutational analysis, we show that Bacillus subtilis δ binds to DNA immediately upstream of the promoter element at A-rich sequences on the abrB and rrnB1 promoters and facilitates open complex formation. As a result, δ facilitates RNAP to initiate transcription in the second scale, compared with minute scale in the absence of δ. Using transcription assay, we show that δ-mediated recycling of RNAP cannot be the sole reason for the enhancement of transcript yield. Our observation that δ does not bind to RNAP holo enzyme but is required to bind to DNA upstream of the -35 promoter element for transcription activation suggests that δ functions as a transcriptional regulator. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Transcription boundaries of U1 small nuclear RNA.

PubMed Central

Kunkel, G R; Pederson, T

1985-01-01

Transcription-proximal stages of U1 small nuclear RNA biosynthesis were studied by 32P labeling of nascent chains in isolated HeLa cell nuclei. Labeled RNA was hybridized to nitrocellulose-immobilized, single-stranded M13 DNA clones corresponding to regions within or flanking a human U1 RNA gene. Transcription of U1 RNA was inhibited by greater than 95% by alpha-amanitin at 1 microgram/ml, consistent with previous evidence that it is synthesized by RNA polymerase II. No hybridization to DNA immediately adjacent to the 5' end of mature U1 RNA (-6 to -105 nucleotides) was detected, indicating that, like all studied polymerase II initiation, transcription of U1 RNA starts at or very near the cap site. However, in contrast to previously described transcription units for mRNA, in which equimolar transcription occurs for hundreds or thousands of nucleotides beyond the mature 3' end of the mRNA, labeled U1 RNA hybridization dropped off sharply within a very short region (approximately 60 nucleotides) immediately downstream from the 3' end of mature U1 RNA. Also in contrast to pre-mRNA, which is assembled into ribonucleoprotein (RNP) particles while still nascent RNA chains, the U1 RNA transcribed in isolated nuclei did not form RNP complexes by the criterion of reaction with a monoclonal antibody for the small nuclear RNP Sm proteins. This suggests that, unlike pre-mRNA-RNP particle formation, U1 small nuclear RNP assembly does not occur until after the completion of transcription. These results show that, despite their common synthesis by RNA polymerase II, mRNA and U1 small nuclear RNA differ markedly both in their extents of 3' processing and their temporal patterns of RNP assembly. Images PMID:2942763

Post-transcriptional regulation tends to attenuate the mRNA noise and to increase the mRNA gain

NASA Astrophysics Data System (ADS)

Shi, Changhong; Wang, Shuqiang; Zhou, Tianshou; Jiang, Yiguo

2015-10-01

Post-transcriptional regulation is ubiquitous in prokaryotic and eukaryotic cells, but how it impacts gene expression remains to be fully explored. Here, we analyze a simple gene model in which we assume that mRNAs are produced in a constitutive manner but are regulated post-transcriptionally by a decapping enzyme that switches between the active state and the inactive state. We derive the analytical mRNA distribution governed by a chemical master equation, which can be well used to analyze the mechanism of how post-transcription regulation influences the mRNA expression level including the mRNA noise. We demonstrate that the mean mRNA level in the stochastic case is always higher than that in the deterministic case due to the stochastic effect of the enzyme, but the size of the increased part depends mainly on the switching rates between two enzyme states. More interesting is that we find that in contrast to transcriptional regulation, post-transcriptional regulation tends to attenuate noise in mRNA. Our results provide insight into the role of post-transcriptional regulation in controlling the transcriptional noise.

Heat-shock inactivation of the TFIIH-associated kinase and change in the phosphorylation sites on the C-terminal domain of RNA polymerase II.

PubMed

Dubois, M F; Vincent, M; Vigneron, M; Adamczewski, J; Egly, J M; Bensaude, O

1997-02-15

The C-terminal domain (CTD) of the RNA polymerase II largest subunit (RPB1) plays a central role in transcription. The CTD is unphosphorylated when the polymerase assembles into a preinitiation complex of transcription and becomes heavily phosphorylated during promoter clearance and entry into elongation of transcription. A kinase associated to the general transcription factor TFIIH, in the preinitiation complex, phosphorylates the CTD. The TFIIH-associated CTD kinase activity was found to decrease in extracts from heat-shocked HeLa cells compared to unstressed cells. This loss of activity correlated with a decreased solubility of the TFIIH factor. The TFIIH-kinase impairment during heat-shock was accompanied by the disappearance of a particular phosphoepitope (CC-3) on the RPB1 subunit. The CC-3 epitope was localized on the C-terminal end of the CTD and generated in vitro when the RPB1 subunit was phosphorylated by the TFIIH-associated kinase but not by another CTD kinase such as MAP kinase. In apparent discrepancy, the overall RPB1 subunit phosphorylation increased during heat-shock. The decreased activity in vivo of the TFIIH kinase might be compensated by a stress-activated CTD kinase such as MAP kinase. These results also suggest that heat-shock gene transcription may have a weak requirement for TFIIH kinase activity.

Heat-shock inactivation of the TFIIH-associated kinase and change in the phosphorylation sites on the C-terminal domain of RNA polymerase II.

PubMed Central

Dubois, M F; Vincent, M; Vigneron, M; Adamczewski, J; Egly, J M; Bensaude, O

1997-01-01

The C-terminal domain (CTD) of the RNA polymerase II largest subunit (RPB1) plays a central role in transcription. The CTD is unphosphorylated when the polymerase assembles into a preinitiation complex of transcription and becomes heavily phosphorylated during promoter clearance and entry into elongation of transcription. A kinase associated to the general transcription factor TFIIH, in the preinitiation complex, phosphorylates the CTD. The TFIIH-associated CTD kinase activity was found to decrease in extracts from heat-shocked HeLa cells compared to unstressed cells. This loss of activity correlated with a decreased solubility of the TFIIH factor. The TFIIH-kinase impairment during heat-shock was accompanied by the disappearance of a particular phosphoepitope (CC-3) on the RPB1 subunit. The CC-3 epitope was localized on the C-terminal end of the CTD and generated in vitro when the RPB1 subunit was phosphorylated by the TFIIH-associated kinase but not by another CTD kinase such as MAP kinase. In apparent discrepancy, the overall RPB1 subunit phosphorylation increased during heat-shock. The decreased activity in vivo of the TFIIH kinase might be compensated by a stress-activated CTD kinase such as MAP kinase. These results also suggest that heat-shock gene transcription may have a weak requirement for TFIIH kinase activity. PMID:9016617

A pause site for RNA polymerase II is associated with termination of transcription.

PubMed Central

Enriquez-Harris, P; Levitt, N; Briggs, D; Proudfoot, N J

1991-01-01

Termination of transcription by RNA polymerase II has been postulated to involve a pausing process. We have identified such a pause signal, 350 bp into the 3' flanking region of the human alpha 2 globin gene at a position where termination is thought to occur. We show that this pause signal enhances the utilization of an upstream poly(A) site which is otherwise out-competed by a stronger downstream poly(A) site. We also demonstrate that the pause site rescues a poly(A) site that is inactive due to its location within an intron. Using nuclear run-on analysis we show that elongating RNA polymerase II molecules accumulate over this pause signal. Furthermore we show that when the pause site is positioned immediately downstream of a strong poly(A) signal, significant levels of transcription termination take place. Images PMID:2050120

Helicase promotes replication re-initiation from an RNA transcript.

PubMed

Sun, Bo; Singh, Anupam; Sultana, Shemaila; Inman, James T; Patel, Smita S; Wang, Michelle D

2018-06-13

To ensure accurate DNA replication, a replisome must effectively overcome numerous obstacles on its DNA substrate. After encountering an obstacle, a progressing replisome often aborts DNA synthesis but continues to unwind. However, little is known about how DNA synthesis is resumed downstream of an obstacle. Here, we examine the consequences of a non-replicating replisome collision with a co-directional RNA polymerase (RNAP). Using single-molecule and ensemble methods, we find that T7 helicase interacts strongly with a non-replicating T7 DNA polymerase (DNAP) at a replication fork. As the helicase advances, the associated DNAP also moves forward. The presence of the DNAP increases both helicase's processivity and unwinding rate. We show that such a DNAP, together with its helicase, is indeed able to actively disrupt a stalled transcription elongation complex, and then initiates replication using the RNA transcript as a primer. These observations exhibit T7 helicase's novel role in replication re-initiation.

RNA Sequencing of the Human Milk Fat Layer Transcriptome Reveals Distinct Gene Expression Profiles at Three Stages of Lactation

PubMed Central

Lemay, Danielle G.; Ballard, Olivia A.; Hughes, Maria A.; Morrow, Ardythe L.; Horseman, Nelson D.; Nommsen-Rivers, Laurie A.

2013-01-01

Aware of the important benefits of human milk, most U.S. women initiate breastfeeding but difficulties with milk supply lead some to quit earlier than intended. Yet, the contribution of maternal physiology to lactation difficulties remains poorly understood. Human milk fat globules, by enveloping cell contents during their secretion into milk, are a rich source of mammary cell RNA. Here, we pair this non-invasive mRNA source with RNA-sequencing to probe the milk fat layer transcriptome during three stages of lactation: colostral, transitional, and mature milk production. The resulting transcriptomes paint an exquisite portrait of human lactation. The resulting transcriptional profiles cluster not by postpartum day, but by milk Na:K ratio, indicating that women sampled during similar postpartum time frames could be at markedly different stages of gene expression. Each stage of lactation is characterized by a dynamic range (105-fold) in transcript abundances not previously observed with microarray technology. We discovered that transcripts for isoferritins and cathepsins are strikingly abundant during colostrum production, highlighting the potential importance of these proteins for neonatal health. Two transcripts, encoding β-casein (CSN2) and α-lactalbumin (LALBA), make up 45% of the total pool of mRNA in mature lactation. Genes significantly expressed across all stages of lactation are associated with making, modifying, transporting, and packaging milk proteins. Stage-specific transcripts are associated with immune defense during the colostral stage, up-regulation of the machinery needed for milk protein synthesis during the transitional stage, and the production of lipids during mature lactation. We observed strong modulation of key genes involved in lactose synthesis and insulin signaling. In particular, protein tyrosine phosphatase, receptor type, F (PTPRF) may serve as a biomarker linking insulin resistance with insufficient milk supply. This study provides the methodology and reference data set to enable future targeted research on the physiological contributors of sub-optimal lactation in humans. PMID:23861770

An oxidative DNA “damage” and repair mechanism localized in the VEGF promoter is important for hypoxia-induced VEGF mRNA expression

PubMed Central

Pastukh, Viktor; Roberts, Justin T.; Clark, David W.; Bardwell, Gina C.; Patel, Mita; Al-Mehdi, Abu-Bakr; Borchert, Glen M.

2015-01-01

In hypoxia, mitochondria-generated reactive oxygen species not only stimulate accumulation of the transcriptional regulator of hypoxic gene expression, hypoxia inducible factor-1 (Hif-1), but also cause oxidative base modifications in hypoxic response elements (HREs) of hypoxia-inducible genes. When the hypoxia-induced base modifications are suppressed, Hif-1 fails to associate with the HRE of the VEGF promoter, and VEGF mRNA accumulation is blunted. The mechanism linking base modifications to transcription is unknown. Here we determined whether recruitment of base excision DNA repair (BER) enzymes in response to hypoxia-induced promoter modifications was required for transcription complex assembly and VEGF mRNA expression. Using chromatin immunoprecipitation analyses in pulmonary artery endothelial cells, we found that hypoxia-mediated formation of the base oxidation product 8-oxoguanine (8-oxoG) in VEGF HREs was temporally associated with binding of Hif-1α and the BER enzymes 8-oxoguanine glycosylase 1 (Ogg1) and redox effector factor-1 (Ref-1)/apurinic/apyrimidinic endonuclease 1 (Ape1) and introduction of DNA strand breaks. Hif-1α colocalized with HRE sequences harboring Ref-1/Ape1, but not Ogg1. Inhibition of BER by small interfering RNA-mediated reduction in Ogg1 augmented hypoxia-induced 8-oxoG accumulation and attenuated Hif-1α and Ref-1/Ape1 binding to VEGF HRE sequences and blunted VEGF mRNA expression. Chromatin immunoprecipitation-sequence analysis of 8-oxoG distribution in hypoxic pulmonary artery endothelial cells showed that most of the oxidized base was localized to promoters with virtually no overlap between normoxic and hypoxic data sets. Transcription of genes whose promoters lost 8-oxoG during hypoxia was reduced, while those gaining 8-oxoG was elevated. Collectively, these findings suggest that the BER pathway links hypoxia-induced introduction of oxidative DNA modifications in promoters of hypoxia-inducible genes to transcriptional activation. PMID:26432868

Effects of RNA integrity on transcript quantification by total RNA sequencing of clinically collected human placental samples.

PubMed

Reiman, Mario; Laan, Maris; Rull, Kristiina; Sõber, Siim

2017-08-01

RNA degradation is a ubiquitous process that occurs in living and dead cells, as well as during handling and storage of extracted RNA. Reduced RNA quality caused by degradation is an established source of uncertainty for all RNA-based gene expression quantification techniques. RNA sequencing is an increasingly preferred method for transcriptome analyses, and dependence of its results on input RNA integrity is of significant practical importance. This study aimed to characterize the effects of varying input RNA integrity [estimated as RNA integrity number (RIN)] on transcript level estimates and delineate the characteristic differences between transcripts that differ in degradation rate. The study used ribodepleted total RNA sequencing data from a real-life clinically collected set ( n = 32) of human solid tissue (placenta) samples. RIN-dependent alterations in gene expression profiles were quantified by using DESeq2 software. Our results indicate that small differences in RNA integrity affect gene expression quantification by introducing a moderate and pervasive bias in expression level estimates that significantly affected 8.1% of studied genes. The rapidly degrading transcript pool was enriched in pseudogenes, short noncoding RNAs, and transcripts with extended 3' untranslated regions. Typical slowly degrading transcripts (median length, 2389 nt) represented protein coding genes with 4-10 exons and high guanine-cytosine content.-Reiman, M., Laan, M., Rull, K., Sõber, S. Effects of RNA integrity on transcript quantification by total RNA sequencing of clinically collected human placental samples. © FASEB.

Latency of Epstein-Barr virus is stabilized by antisense-mediated control of the viral immediate-early gene BZLF-1.

PubMed

Prang, N; Wolf, H; Schwarzmann, F

1999-12-01

The ability of the Epstein-Barr virus (EBV) to avoid lytic replication and to establish a latent infection in B-lymphocytes is fundamental for its lifelong persistence and the pathogenesis of various EBV-associated diseases. The viral immediate-early gene BZLF-1 plays a key role for the induction of lytic replication and its activity is strictly regulated on different levels of gene expression. Recently, it was demonstrated that BZLF-1 is also controlled by a posttranscriptional mechanism. Transient synthesis of a mutated competitor RNA saturated this mechanism and caused both expression of the BZLF-1 protein and the induction of lytic viral replication. Using short overlapping fragments of the competitor, it is shown that this control acts on the unspliced primary transcript. RT-PCR demonstrated unspliced BZLF-1 RNA in latently infected B-lymphocytes in the absence of BZLF-1 protein. Due to the complementarity of the gene BZLF-1 and the latency-associated gene EBNA-1 on the opposite strand of the genome, we propose an antisense-mediated mechanism. RNase protection assays demonstrated transcripts in antisense orientation to the BZLF-1 transcript during latency, which comprise a comparable constellation to other herpesviruses. A combined RNAse protection/RT-PCR assay detected the double-stranded hybrid RNA, consisting of the unspliced BZLF-1 transcript and a noncoding intron of the EBNA-1 gene. Binding of BZLF-1 transcripts is suggested to be an important backup control mechanism in addition to transcriptional regulation, stabilizing latency and preventing inappropriate lytic viral replication in vivo. Copyright 1999 Wiley-Liss, Inc.

Conserved RNA binding activity of a Yin-Yang 1 homologue in the ova of the purple sea urchin Strongylocentrotus purpuratus.

PubMed

Belak, Zachery R; Ovsenek, Nicholas; Eskiw, Christopher H

2018-05-23

Yin-Yang 1 (YY1) is a highly conserved transcription factor possessing RNA-binding activity. A putative YY1 homologue was previously identified in the developmental model organism Strongylocentrotus purpuratus (the purple sea urchin) by genomic sequencing. We identified a high degree of sequence similarity with YY1 homologues of vertebrate origin which shared 100% protein sequence identity over the DNA- and RNA-binding zinc-finger region with high similarity in the N-terminal transcriptional activation domain. SpYY1 demonstrated identical DNA- and RNA-binding characteristics between Xenopus laevis and S. purpuratus indicating that it maintains similar functional and biochemical properties across widely divergent deuterostome species. SpYY1 binds to the consensus YY1 DNA element, and also to U-rich RNA sequences. Although we detected SpYY1 RNA-binding activity in ova lysates and observed cytoplasmic localization, SpYY1 was not associated with maternal mRNA in ova. SpYY1 expressed in Xenopus oocytes was excluded from the nucleus and associated with maternally expressed cytoplasmic mRNA molecules. These data demonstrate the existence of an YY1 homologue in S. purpuratus with similar structural and biochemical features to those of the well-studied vertebrate YY1; however, the data reveal major differences in the biological role of YY1 in the regulation of maternally expressed mRNA in the two species.

MicroRNAs associated with muscle growth and fillet quality in rainbow trout

USDA-ARS?s Scientific Manuscript database

Selection for improved muscle growth and quality phenotypes requires understanding of post-transcriptional gene-regulation mechanisms. To investigate role of microRNAs in muscle post-transcriptional gene regulation, RNA-seq was used to identify differential expression in microRNAs and SNPs in microR...

Identification and Characterization of Tumor Antigens Associated With Breast Cancer

DTIC Science & Technology

1998-08-01

including mental retardation and alpha- thalassemia (9). The RNA transcript was shown to exist at high levels in B 16 melanoma cells and moderate levels in...D.R. Mutations in a putative global transcriptional regulator cause X-linked mental retardation with alpha- thalassemia (ATRX syndrome). Cell (80): 837

An origin of the immunogenicity of in vitro transcribed RNA.

PubMed

Mu, Xin; Greenwald, Emily; Ahmad, Sadeem; Hur, Sun

2018-06-01

The emergence of RNA-based therapeutics demands robust and economical methods to produce RNA with few byproducts from aberrant activity. While in vitro transcription using the bacteriophage T7 RNA polymerase is one such popular method, its transcripts are known to display an immune-stimulatory activity that is often undesirable and uncontrollable. We here showed that the immune-stimulatory activity of T7 transcript is contributed by its aberrant activity to initiate transcription from a promoter-less DNA end. This activity results in the production of an antisense RNA that is fully complementary to the intended sense RNA product, and consequently a long double-stranded RNA (dsRNA) that can robustly stimulate a cytosolic pattern recognition receptor, MDA5. This promoter-independent transcriptional activity of the T7 RNA polymerase was observed for a wide range of DNA sequences and lengths, but can be suppressed by altering the transcription reaction with modified nucleotides or by reducing the Mg2+ concentration. The current work thus not only offers a previously unappreciated mechanism by which T7 transcripts stimulate the innate immune system, but also shows that the immune-stimulatory activity can be readily regulated.

DNMT1-interacting RNAs block gene specific DNA methylation

PubMed Central

Di Ruscio, Annalisa; Ebralidze, Alexander K.; Benoukraf, Touati; Amabile, Giovanni; Goff, Loyal A.; Terragni, Joylon; Figueroa, Maria Eugenia; De Figureido Pontes, Lorena Lobo; Alberich-Jorda, Meritxell; Zhang, Pu; Wu, Mengchu; D’Alò, Francesco; Melnick, Ari; Leone, Giuseppe; Ebralidze, Konstantin K.; Pradhan, Sriharsa; Rinn, John L.; Tenen, Daniel G.

2013-01-01

Summary DNA methylation was described almost a century ago. However, the rules governing its establishment and maintenance remain elusive. Here, we present data demonstrating that active transcription regulates levels of genomic methylation. We identified a novel RNA arising from the CEBPA gene locus critical in regulating the local DNA methylation profile. This RNA binds to DNMT1 and prevents CEBPA gene locus methylation. Deep sequencing of transcripts associated with DNMT1 combined with genome-scale methylation and expression profiling extended the generality of this finding to numerous gene loci. Collectively, these results delineate the nature of DNMT1-RNA interactions and suggest strategies for gene selective demethylation of therapeutic targets in disease. PMID:24107992

The transcriptional terminator sequences downstream of the covR gene terminate covR/S operon transcription to generate covR monocistronic transcripts in Streptococcus pyogenes.

PubMed

Chiang-Ni, Chuan; Tsou, Chih-Cheng; Lin, Yee-Shin; Chuang, Woei-Jer; Lin, Ming-T; Liu, Ching-Chuan; Wu, Jiunn-Jong

2008-12-31

CovR/S is an important two component regulatory system, which regulates about 15% of the gene expression in Streptococcus pyogenes. The covR/S locus was identified as an operon generating an RNA transcript around 2.5-kb in size. In this study, we found the covR/S operon produced three RNA transcripts (around 2.5-, 1.0-, and 0.8-kb in size). Using RNA transcriptional terminator sequence prediction and transcriptional terminator analysis, we identified two atypical rho-independent terminator sequences downstream of the covR gene and showed these terminator sequences terminate RNA transcription efficiently. These results indicate that covR/S operon generates covR/S transcript and monocistronic covR transcripts.

Increased global transcription activity as a mechanism of replication stress in cancer

PubMed Central

Kotsantis, Panagiotis; Silva, Lara Marques; Irmscher, Sarah; Jones, Rebecca M.; Folkes, Lisa; Gromak, Natalia; Petermann, Eva

2016-01-01

Cancer is a disease associated with genomic instability that often results from oncogene activation. This in turn leads to hyperproliferation and replication stress. However, the molecular mechanisms that underlie oncogene-induced replication stress are still poorly understood. Oncogenes such as HRASV12 promote proliferation by upregulating general transcription factors to stimulate RNA synthesis. Here we investigate whether this increase in transcription underlies oncogene-induced replication stress. We show that in cells overexpressing HRASV12, elevated expression of the general transcription factor TATA-box binding protein (TBP) leads to increased RNA synthesis, which together with R-loop accumulation results in replication fork slowing and DNA damage. Furthermore, overexpression of TBP alone causes the hallmarks of oncogene-induced replication stress, including replication fork slowing, DNA damage and senescence. Consequently, we reveal that increased transcription can be a mechanism of oncogene-induced DNA damage, providing a molecular link between upregulation of the transcription machinery and genomic instability in cancer. PMID:27725641

Increased global transcription activity as a mechanism of replication stress in cancer.

PubMed

Kotsantis, Panagiotis; Silva, Lara Marques; Irmscher, Sarah; Jones, Rebecca M; Folkes, Lisa; Gromak, Natalia; Petermann, Eva

2016-10-11

Cancer is a disease associated with genomic instability that often results from oncogene activation. This in turn leads to hyperproliferation and replication stress. However, the molecular mechanisms that underlie oncogene-induced replication stress are still poorly understood. Oncogenes such as HRAS V12 promote proliferation by upregulating general transcription factors to stimulate RNA synthesis. Here we investigate whether this increase in transcription underlies oncogene-induced replication stress. We show that in cells overexpressing HRAS V12 , elevated expression of the general transcription factor TATA-box binding protein (TBP) leads to increased RNA synthesis, which together with R-loop accumulation results in replication fork slowing and DNA damage. Furthermore, overexpression of TBP alone causes the hallmarks of oncogene-induced replication stress, including replication fork slowing, DNA damage and senescence. Consequently, we reveal that increased transcription can be a mechanism of oncogene-induced DNA damage, providing a molecular link between upregulation of the transcription machinery and genomic instability in cancer.

In Vivo Delivery of Cytoplasmic RNA Virus-derived miRNAs

PubMed Central

Langlois, Ryan A; Shapiro, Jillian S; Pham, Alissa M; tenOever, Benjamin R

2012-01-01

The discovery of microRNAs (miRNAs) revealed an unappreciated level of post-transcriptional control used by the cell to maintain optimal protein levels. This process has represented an attractive strategy for therapeutics that is currently limited by in vivo delivery constraints. Here, we describe the generation of a single-stranded, cytoplasmic virus of negative polarity capable of producing functional miRNAs. Cytoplasmic RNA virus-derived miRNAs accumulated to high levels in vitro, generated significant amounts of miRNA star strand, associated with the RNA-induced silencing complex (RISC), and conferred post transcriptional gene silencing in a sequence-specific manner. Furthermore, we demonstrate that these vectors could deliver miRNAs to a wide range of tissues, and sustain prolonged expression capable of achieving measurable knockdown of physiological targets in vivo. Taken together, these results validate noncanonical processing of cytoplasmic-derived miRNAs and provide a novel platform for small RNA delivery. PMID:22086233

Conserved mRNA-binding proteomes in eukaryotic organisms.

PubMed

Matia-González, Ana M; Laing, Emma E; Gerber, André P

2015-12-01

RNA-binding proteins (RBPs) are essential for post-transcriptional regulation of gene expression. Recent high-throughput screens have dramatically increased the number of experimentally identified RBPs; however, comprehensive identification of RBPs within living organisms is elusive. Here we describe the repertoire of 765 and 594 proteins that reproducibly interact with polyadenylated mRNAs in Saccharomyces cerevisiae and Caenorhabditis elegans, respectively. Furthermore, we report the differential association of mRNA-binding proteins (mRPBs) upon induction of apoptosis in C. elegans L4-stage larvae. Strikingly, most proteins composing mRBPomes, including components of early metabolic pathways and the proteasome, are evolutionarily conserved between yeast and C. elegans. We speculate, on the basis of our evidence that glycolytic enzymes bind distinct glycolytic mRNAs, that enzyme-mRNA interactions relate to an ancient mechanism for post-transcriptional coordination of metabolic pathways that perhaps was established during the transition from the early 'RNA world' to the 'protein world'.

Differentiation-induced Colocalization of the KH-type Splicing Regulatory Protein with Polypyrimidine Tract Binding Protein and the c-src Pre-mRNA

PubMed Central

Hall, Megan P.; Huang, Sui; Black, Douglas L.

2004-01-01

We have examined the subcellular localization of the KH-type splicing regulatory protein (KSRP). KSRP is a multidomain RNA-binding protein implicated in a variety of cellular processes, including splicing in the nucleus and mRNA localization in the cytoplasm. We find that KSRP is primarily nuclear with a localization pattern that most closely resembles that of polypyrimidine tract binding protein (PTB). Colocalization experiments of KSRP with PTB in a mouse neuroblastoma cell line determined that both proteins are present in the perinucleolar compartment (PNC), as well as in other nuclear enrichments. In contrast, HeLa cells do not show prominent KSRP staining in the PNC, even though PTB labeling identified the PNC in these cells. Because both PTB and KSRP interact with the c-src transcript to affect N1 exon splicing, we examined the localization of the c-src pre-mRNA by fluorescence in situ hybridization. The src transcript is present in specific foci within the nucleus that are presumably sites of src transcription but are not generally perinucleolar. In normally cultured neuroblastoma cells, these src RNA foci contain PTB, but little KSRP. However, upon induced neuronal differentiation of these cells, KSRP occurs in the same foci with src RNA. PTB localization remains unaffected. This differentiation-induced localization of KSRP with src RNA correlates with an increase in src exon N1 inclusion. These results indicate that PTB and KSRP do indeed interact with the c-src transcript in vivo, and that these associations change with the differentiated state of the cell. PMID:14657238

Regulation of glucose-dependent gene expression by the RNA helicase Dbp2 in Saccharomyces cerevisiae.

PubMed

Beck, Zachary T; Cloutier, Sara C; Schipma, Matthew J; Petell, Christopher J; Ma, Wai Kit; Tran, Elizabeth J

2014-11-01

Cellular homeostasis requires a fine balance between energy uptake, utilization, and growth. Dbp2 is a member of the DEAD-box protein family in Saccharomyces cerevisiae with characterized ATPase and helicase activity in vitro. DEAD-box RNA helicases are a class of enzymes that utilize ATP hydrolysis to remodel RNA and/or RNA-protein (RNP) composition. Dbp2 has been proposed to utilize its helicase activity in vivo to promote RNA-protein complex assembly of both messenger (m)RNAs and long noncoding (lnc)RNAs. Previous work from our laboratory demonstrated that loss of DBP2 enhances the lncRNA-dependent transcriptional induction of the GAL genes by abolishing glucose-dependent repression. Herein, we report that either a carbon source switch or glucose deprivation results in rapid export of Dbp2 to the cytoplasm. Genome-wide RNA sequencing identified a new class of antisense hexose transporter transcripts that are specifically upregulated upon loss of DBP2. Further investigation revealed that both sense and antisense hexose transporter (HXT) transcripts are aberrantly expressed in DBP2-deficient cells and that this expression pathway can be partially mimicked in wild-type cells by glucose depletion. We also find that Dbp2 promotes ribosome biogenesis and represses alternative ATP-producing pathways, as loss of DBP2 alters the transcript levels of ribosome biosynthesis (snoRNAs and associated proteins) and respiration gene products. This suggests that Dbp2 is a key integrator of nutritional status and gene expression programs required for energy homeostasis. Copyright © 2014 by the Genetics Society of America.

Triplet repeat RNA structure and its role as pathogenic agent and therapeutic target

PubMed Central

Krzyzosiak, Wlodzimierz J.; Sobczak, Krzysztof; Wojciechowska, Marzena; Fiszer, Agnieszka; Mykowska, Agnieszka; Kozlowski, Piotr

2012-01-01

This review presents detailed information about the structure of triplet repeat RNA and addresses the simple sequence repeats of normal and expanded lengths in the context of the physiological and pathogenic roles played in human cells. First, we discuss the occurrence and frequency of various trinucleotide repeats in transcripts and classify them according to the propensity to form RNA structures of different architectures and stabilities. We show that repeats capable of forming hairpin structures are overrepresented in exons, which implies that they may have important functions. We further describe long triplet repeat RNA as a pathogenic agent by presenting human neurological diseases caused by triplet repeat expansions in which mutant RNA gains a toxic function. Prominent examples of these diseases include myotonic dystrophy type 1 and fragile X-associated tremor ataxia syndrome, which are triggered by mutant CUG and CGG repeats, respectively. In addition, we discuss RNA-mediated pathogenesis in polyglutamine disorders such as Huntington's disease and spinocerebellar ataxia type 3, in which expanded CAG repeats may act as an auxiliary toxic agent. Finally, triplet repeat RNA is presented as a therapeutic target. We describe various concepts and approaches aimed at the selective inhibition of mutant transcript activity in experimental therapies developed for repeat-associated diseases. PMID:21908410

Cellular microRNAs up-regulate transcription via interaction with promoter TATA-box motifs.

PubMed

Zhang, Yijun; Fan, Miaomiao; Zhang, Xue; Huang, Feng; Wu, Kang; Zhang, Junsong; Liu, Jun; Huang, Zhuoqiong; Luo, Haihua; Tao, Liang; Zhang, Hui

2014-12-01

The TATA box represents one of the most prevalent core promoters where the pre-initiation complexes (PICs) for gene transcription are assembled. This assembly is crucial for transcription initiation and well regulated. Here we show that some cellular microRNAs (miRNAs) are associated with RNA polymerase II (Pol II) and TATA box-binding protein (TBP) in human peripheral blood mononuclear cells (PBMCs). Among them, let-7i sequence specifically binds to the TATA-box motif of interleukin-2 (IL-2) gene and elevates IL-2 mRNA and protein production in CD4(+) T-lymphocytes in vitro and in vivo. Through direct interaction with the TATA-box motif, let-7i facilitates the PIC assembly and transcription initiation of IL-2 promoter. Several other cellular miRNAs, such as mir-138, mir-92a or mir-181d, also enhance the promoter activities via binding to the TATA-box motifs of insulin, calcitonin or c-myc, respectively. In agreement with the finding that an HIV-1-encoded miRNA could enhance viral replication through targeting the viral promoter TATA-box motif, our data demonstrate that the interaction with core transcription machinery is a novel mechanism for miRNAs to regulate gene expression. © 2014 Zhang et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

BRF1 mutations alter RNA polymerase III–dependent transcription and cause neurodevelopmental anomalies

PubMed Central

Hög, Friederike; Dentici, Maria Lisa; Tan, Perciliz L.; Sowada, Nadine; Medeira, Ana; Gueneau, Lucie; Thiele, Holger; Kousi, Maria; Lepri, Francesca; Wenzeck, Larissa; Blumenthal, Ian; Radicioni, Antonio; Schwarzenberg, Tito Livio; Mandriani, Barbara; Fischetto, Rita; Morris-Rosendahl, Deborah J.; Altmüller, Janine; Reymond, Alexandre; Nürnberg, Peter; Merla, Giuseppe; Dallapiccola, Bruno; Katsanis, Nicholas; Cramer, Patrick; Kubisch, Christian

2015-01-01

RNA polymerase III (Pol III) synthesizes tRNAs and other small noncoding RNAs to regulate protein synthesis. Dysregulation of Pol III transcription has been linked to cancer, and germline mutations in genes encoding Pol III subunits or tRNA processing factors cause neurogenetic disorders in humans, such as hypomyelinating leukodystrophies and pontocerebellar hypoplasia. Here we describe an autosomal recessive disorder characterized by cerebellar hypoplasia and intellectual disability, as well as facial dysmorphic features, short stature, microcephaly, and dental anomalies. Whole-exome sequencing revealed biallelic missense alterations of BRF1 in three families. In support of the pathogenic potential of the discovered alleles, suppression or CRISPR-mediated deletion of brf1 in zebrafish embryos recapitulated key neurodevelopmental phenotypes; in vivo complementation showed all four candidate mutations to be pathogenic in an apparent isoform-specific context. BRF1 associates with BDP1 and TBP to form the transcription factor IIIB (TFIIIB), which recruits Pol III to target genes. We show that disease-causing mutations reduce Brf1 occupancy at tRNA target genes in Saccharomyces cerevisiae and impair cell growth. Moreover, BRF1 mutations reduce Pol III–related transcription activity in vitro. Taken together, our data show that BRF1 mutations that reduce protein activity cause neurodevelopmental anomalies, suggesting that BRF1-mediated Pol III transcription is required for normal cerebellar and cognitive development. PMID:25561519

Mechanism and manipulation of DNA:RNA hybrid G-quadruplex formation in transcription of G-rich DNA.

PubMed

Zhang, Jia-yu; Zheng, Ke-wei; Xiao, Shan; Hao, Yu-hua; Tan, Zheng

2014-01-29

We recently reported that a DNA:RNA hybrid G-quadruplex (HQ) forms during transcription of DNA that bears two or more tandem guanine tracts (G-tract) on the nontemplate strand. Putative HQ-forming sequences are enriched in the nearby 1000 nt region right downstream of transcription start sites in the nontemplate strand of warm-blooded animals, and HQ regulates transcription under both in vitro and in vivo conditions. Therefore, knowledge of the mechanism of HQ formation is important for understanding the biological function of HQ as well as for manipulating gene expression by targeting HQ. In this work, we studied the mechanism of HQ formation using an in vitro T7 transcription model. We show that RNA synthesis initially produces an R-loop, a DNA:RNA heteroduplex formed by a nascent RNA transcript and the template DNA strand. In the following round of transcription, the RNA in the R-loop is displaced, releasing the RNA in single-stranded form (ssRNA). Then the G-tracts in the RNA can jointly form HQ with those in the nontemplate DNA strand. We demonstrate that the structural cascade R-loop → ssRNA → HQ offers opportunities to intercept HQ formation, which may provide a potential method to manipulate gene expression.

Transcriptional mapping of the ribosomal RNA region of mouse L-cell mitochondrial DNA.

PubMed Central

Nagley, P; Clayton, D A

1980-01-01

The map positions in mouse mitochondrial DNA of the two ribosomal RNA genes and adjacent genes coding several small transcripts have been determined precisely by application of a procedure in which DNA-RNA hybrids have been subjected to digestion by S1 nuclease under conditions of varying severity. Digestion of the DNA-RNA hybrids with S1 nuclease yielded a series of species which were shown to contain ribosomal RNA molecules together with adjacent transcripts hybridized conjointly to a continuous segment of mitochondrial DNA. There is one small transcript about 60 bases long whose gene adjoins the sequences coding the 5'-end of the small ribosomal RNA (950 bases) and which lies approximately 200 nucleotides from the D-loop origin of heavy strand mitochondrial DNA synthesis. An 80-base transcript lies between the small and large ribosomal RNA genes, and genes for two further short transcript (each about 80 bases in length) abut the sequences coding the 3'-end of the large ribosomal RNA (approximately 1500 bases). The ability to isolate a discrete DNA-RNA hybrid species approximately 2700 base pairs in length containing all these transcripts suggests that there can be few nucleotides in this region of mouse mitochondrial DNA which are not represented as stable RNA species. Images PMID:6253898

A transgenic mouse for imaging activity-dependent dynamics of endogenous Arc mRNA in live neurons.

PubMed

Das, Sulagna; Moon, Hyungseok C; Singer, Robert H; Park, Hye Yoon

2018-06-01

Localized translation plays a crucial role in synaptic plasticity and memory consolidation. However, it has not been possible to follow the dynamics of memory-associated mRNAs in living neurons in response to neuronal activity in real time. We have generated a novel mouse model where the endogenous Arc/Arg3.1 gene is tagged in its 3' untranslated region with stem-loops that bind a bacteriophage PP7 coat protein (PCP), allowing visualization of individual mRNAs in real time. The physiological response of the tagged gene to neuronal activity is identical to endogenous Arc and reports the true dynamics of Arc mRNA from transcription to degradation. The transcription dynamics of Arc in cultured hippocampal neurons revealed two novel results: (i) A robust transcriptional burst with prolonged ON state occurs after stimulation, and (ii) transcription cycles continue even after initial stimulation is removed. The correlation of stimulation with Arc transcription and mRNA transport in individual neurons revealed that stimulus-induced Ca 2+ activity was necessary but not sufficient for triggering Arc transcription and that blocking neuronal activity did not affect the dendritic transport of newly synthesized Arc mRNAs. This mouse will provide an important reagent to investigate how individual neurons transduce activity into spatiotemporal regulation of gene expression at the synapse.

RINT-1 interacts with MSP58 within nucleoli and plays a role in ribosomal gene transcription.

PubMed

Yang, Chuan-Pin; Kuo, Yu-Liang; Lee, Yi-Chao; Lee, Kuen-Haur; Chiang, Chi-Wu; Wang, Ju-Ming; Hsu, Che-Chia; Chang, Wen-Chang; Lin, Ding-Yen

2016-09-16

The nucleolus is the cellular site of ribosomal (r)DNA transcription and ribosome biogenesis. The 58-kDa microspherule protein (MSP58) is a nucleolar protein involved in rDNA transcription and cell proliferation. However, regulation of MSP58-mediated rDNA transcription remains unknown. Using a yeast two-hybrid system with MSP58 as bait, we isolated complementary (c)DNA encoding Rad50-interacting protein 1 (RINT-1), as a MSP58-binding protein. RINT-1 was implicated in the cell cycle checkpoint, membrane trafficking, Golgi apparatus and centrosome dynamic integrity, and telomere length control. Both in vitro and in vivo interaction assays showed that MSP58 directly interacts with RINT-1. Interestingly, microscopic studies revealed the co-localization of MSP58, RINT-1, and the upstream binding factor (UBF), a rRNA transcription factor, in the nucleolus. We showed that ectopic expression of MSP58 or RINT-1 resulted in decreased rRNA expression and rDNA promoter activity, whereas knockdown of MSP58 or RINT-1 by siRNA exerted the opposite effect. Coexpression of MSP58 and RINT-1 robustly decreased rRNA synthesis compared to overexpression of either protein alone, whereas depletion of RINT-1 from MSP58-transfected cells enhanced rRNA synthesis. We also found that MSP58, RINT-1, and the UBF were associated with the rDNA promoter using a chromatin immunoprecipitation assay. Because aberrant ribosome biogenesis contributes to neoplastic transformation, our results revealed a novel protein complex involved in the regulation of rRNA gene expression, suggesting a role for MSP58 and RINT-1 in cancer development. Copyright © 2016 Elsevier Inc. All rights reserved.

Identification of an Enhancer That Increases miR-200b~200a~429 Gene Expression in Breast Cancer Cells

PubMed Central

Attema, Joanne L.; Bert, Andrew G.; Lim, Yat-Yuen; Kolesnikoff, Natasha; Lawrence, David M.; Pillman, Katherine A.; Smith, Eric; Drew, Paul A.; Khew-Goodall, Yeesim; Shannon, Frances; Goodall, Gregory J.

2013-01-01

The miR-200b~200a~429 gene cluster is a key regulator of EMT and cancer metastasis, however the transcription-based mechanisms controlling its expression during this process are not well understood. We have analyzed the miR-200b~200a~429 locus for epigenetic modifications in breast epithelial and mesenchymal cell lines using chromatin immunoprecipitation assays and DNA methylation analysis. We discovered a novel enhancer located approximately 5.1kb upstream of the miR-200b~200a~429 transcriptional start site. This region was associated with the active enhancer chromatin signature comprising H3K4me1, H3K27ac, RNA polymerase II and CpG dinucleotide hypomethylation. Luciferase reporter assays revealed the upstream enhancer stimulated the transcription of the miR-200b~200a~429 minimal promoter region approximately 27-fold in breast epithelial cells. Furthermore, we found that a region of the enhancer was transcribed, producing a short, GC-rich, mainly nuclear, non-polyadenylated RNA transcript designated miR-200b eRNA. Over-expression of miR-200b eRNA had little effect on miR-200b~200a~429 promoter activity and its production did not correlate with miR-200b~200a~429 gene expression. While additional investigations of miR-200b eRNA function will be necessary, it is possible that miR-200b eRNA may be involved in the regulation of miR-200b~200a~429 gene expression and silencing. Taken together, these findings reveal the presence of a novel enhancer, which contributes to miR-200b~200a~429 transcriptional regulation in epithelial cells. PMID:24086551

Integrated microRNA and mRNA signatures in peripheral blood lymphocytes of familial epithelial ovarian cancer.

PubMed

Dou, Yun-De; Huang, Tao; Wang, Qun; Shu, Xin; Zhao, Shi-Gang; Li, Lei; Liu, Tao; Lu, Gang; Chan, Wai-Yee; Liu, Hong-Bin

2018-01-29

Characterization of the genetic landscapes of familial ovarian cancer through integrated analysis of microRNA and mRNA by partial least squares (PLS) and Monte Carlo technique based on genome-wide association studies (GWAS). The miRNA and mRNA transcriptional data in familial ovarian cancer were characterized from the Gene Expression Omnibus (GEO) database. The miRNA and mRNA expression profiles in peripheral blood lymphocytes (PBLs) of 74 familial ovarian cancer patients and 47 control subjects were analyzed with the integration of partial least squares (PLS) and Monte Carlo techniques. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were also performed. Total of 16 miRNA-mRNA pairs were identified with the target gene prediction results of miRNAs and mRNAs. An innovated miRNA-mRNA integrated network was constructed in which 6 downregulated miRNAs and 1 upregulated miRNAs were included. KEGG and GO pathway enrichment analysis revealed over-representation of dysregulated miRNAs in various biological processes especially in cancer pathology. Hsa-miR-34b played a pivotal role in this network and interacted with other miRNAs. Hsa-miR-136 and hsa-miR-335 were associated with p53 and Erk1/2 pathways and tumor suppressors, such as PTEN. The results from this research provide insights on miRNA-mRNA networks and offer new tools for studying transcriptional variants in familial ovarian cancer. Copyright © 2018 Elsevier Inc. All rights reserved.

Nonproteolytic Roles of 19S ATPases in Transcription of CIITApIV Genes

PubMed Central

Maganti, Nagini; Moody, Tomika D.; Truax, Agnieszka D.; Thakkar, Meghna; Spring, Alexander M.; Germann, Markus W.; Greer, Susanna F.

2014-01-01

Accumulating evidence shows the 26S proteasome is involved in the regulation of gene expression. We and others have demonstrated that proteasome components bind to sites of gene transcription, regulate covalent modifications to histones, and are involved in the assembly of activator complexes in mammalian cells. The mechanisms by which the proteasome influences transcription remain unclear, although prior observations suggest both proteolytic and non-proteolytic activities. Here, we define novel, non-proteolytic, roles for each of the three 19S heterodimers, represented by the 19S ATPases Sug1, S7, and S6a, in mammalian gene expression using the inflammatory gene CIITApIV. These 19S ATPases are recruited to induced CIITApIV promoters and also associate with CIITA coding regions. Additionally, these ATPases interact with elongation factor PTEFb complex members CDK9 and Hexim-1 and with Ser5 phosphorylated RNA Pol II. Both the generation of transcripts from CIITApIV and efficient recruitment of RNA Pol II to CIITApIV are negatively impacted by siRNA mediated knockdown of these 19S ATPases. Together, these results define novel roles for 19S ATPases in mammalian gene expression and indicate roles for these ATPases in promoting transcription processes. PMID:24625964

Selective nuclear export of specific classes of mRNA from mammalian nuclei is promoted by GANP

PubMed Central

Wickramasinghe, Vihandha O.; Andrews, Robert; Ellis, Peter; Langford, Cordelia; Gurdon, John B.; Stewart, Murray; Venkitaraman, Ashok R.; Laskey, Ronald A.

2014-01-01

The nuclear phase of the gene expression pathway culminates in the export of mature messenger RNAs (mRNAs) to the cytoplasm through nuclear pore complexes. GANP (germinal- centre associated nuclear protein) promotes the transfer of mRNAs bound to the transport factor NXF1 to nuclear pore complexes. Here, we demonstrate that GANP, subunit of the TRanscription-EXport-2 (TREX-2) mRNA export complex, promotes selective nuclear export of a specific subset of mRNAs whose transport depends on NXF1. Genome-wide gene expression profiling showed that half of the transcripts whose nuclear export was impaired following NXF1 depletion also showed reduced export when GANP was depleted. GANP-dependent transcripts were highly expressed, yet short-lived, and were highly enriched in those encoding central components of the gene expression machinery such as RNA synthesis and processing factors. After injection into Xenopus oocyte nuclei, representative GANP-dependent transcripts showed faster nuclear export kinetics than representative transcripts that were not influenced by GANP depletion. We propose that GANP promotes the nuclear export of specific classes of mRNAs that may facilitate rapid changes in gene expression. PMID:24510098

Transcriptome Complexity and Riboregulation in the Human Pathogen Helicobacter pylori

PubMed Central

Pernitzsch, Sandy R.; Sharma, Cynthia M.

2012-01-01

The Gram-negative Epsilonproteobacterium Helicobacter pylori is considered as one of the major human pathogens and many studies have focused on its virulence mechanisms as well as genomic diversity. In contrast, only very little is known about post-transcriptional regulation and small regulatory RNAs (sRNAs) in this spiral-shaped microaerophilic bacterium. Considering the absence of the common RNA chaperone Hfq, which is a key-player in post-transcriptional regulation in enterobacteria, H. pylori was even regarded as an organism without riboregulation. However, analysis of the H. pylori primary transcriptome using RNA-seq revealed a very complex transcriptional output from its small genome. Furthermore, the identification of a wealth of sRNAs as well as massive antisense transcription indicates that H. pylori uses riboregulation for its gene expression control. The ongoing functional characterization of sRNAs along with the identification of associated RNA binding proteins will help to understand their potential roles in Helicobacter virulence and stress response. Moreover, research on riboregulation in H. pylori will provide new insights into its virulence mechanisms and will also help to shed light on post-transcriptional regulation in other Epsilonproteobacteria, including widespread and emerging pathogens such as Campylobacter. PMID:22919606

CK2 is responsible for phosphorylation of human La protein serine-366 and can modulate rpL37 5'-terminal oligopyrimidine mRNA metabolism.

PubMed

Schwartz, Elena I; Intine, Robert V; Maraia, Richard J

2004-11-01

La protein binds precursors to 5S rRNA, tRNAs, and other transcripts that contain 3' UUU-OH and also promotes their maturation in the nucleus. Separate from this function, human La has been shown to positively modulate the translation of mRNAs that contain complex 5' regulatory motifs that direct internal initiation of translation. Nonphosphorylated La (npLa) inhibits pre-tRNA processing, while phosphorylation of human La serine-366 (S(366)) promotes pre-tRNA processing. npLa was found specifically associated with a class of mRNAs that have unusually short 5' untranslated regions comprised of terminal oligopyrimidine (5'TOP) tracts and that encode ribosomal proteins and translation elongation factors. Although La S(366) represents a CK2 phosphorylation site, there was no evidence that CK2 phosphorylates it in vivo. We used the CK2-specific inhibitor, 4,5,6,7-tetrabromo-2-azabenzimidazole (TBB), and antisense-mediated knockdown to demonstrate that CK2 is responsible for La S(366) phosphorylation in vivo. Hypophosphorylation was not associated with significant change in total La levels or proteolytic cleavage. Quantitative reverse transcription-PCR revealed increased association of the 5'TOP-mRNA encoding ribosomal protein L37 (rpL37) with La after TBB treatment. Transfection revealed more rpL37 mRNA associated with nonphosphorylatable La A(366) than with La S(366), concomitant with La A(366)-specific shift of a fraction of L37 mRNA off polysomes. The data indicate that CK2 phosphorylates La S(366) in vivo, that this limits 5'TOP mRNA binding, and that increasing npLa leads to greater association with potentially negative effects on TOP mRNA translation. Consistent with data that indicate that phosphorylation reverses negative effects of npLa on tRNA production, the present data suggest that CK2 phosphorylation of La can affect production of the translational machinery.

Saccharomyces cerevisiae Sen1 Helicase Domain Exhibits 5'- to 3'-Helicase Activity with a Preference for Translocation on DNA Rather than RNA.

PubMed

Martin-Tumasz, Stephen; Brow, David A

2015-09-18

In the yeast Saccharomyces cerevisiae, the essential nuclear helicase Sen1 is required for efficient termination of transcription of short noncoding RNA genes by RNA polymerase II. However, the mechanism by which Sen1 promotes transcription termination is not known. Prior biochemical studies on the Sen1 homolog from Schizosaccharomyces pombe showed that it can bind and unwind both DNA and RNA, but the S. pombe protein is not essential and has not been demonstrated to function in transcription. Furthermore, Sen1 from either yeast has not previously been expressed as a recombinant protein, due to its large molecular mass (252 kDa in S. cerevisiae). Here, we report the purification and characterization of the 89-kDa S. cerevisiae Sen1 helicase domain (Sen1-HD) produced in Escherichia coli. Sen1-HD binds single-stranded RNA and DNA with similar affinity in the absence of ATP, but it binds RNA more stably than DNA in the presence of ATP, apparently due to a slower translocation rate on RNA. Translocation occurs in the 5' to 3' direction, as for the S. pombe protein. When purified from E. coli at a moderate salt concentration, Sen1-HD was associated with short RNAs that are enriched for the trinucleotide repeat (CAN)4. We propose that Sen1 binds to RNAs and prevents their stable pairing with DNA, consistent with in vivo studies by others showing increased R-loop (RNA/DNA hybrid) formation when Sen1 activity is impaired by mutations. Our results are consistent with a model in which Sen1 promotes transcription termination by resolving R-loops. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

The majority of total nuclear-encoded non-ribosomal RNA in a human cell is 'dark matter' un-annotated RNA.

PubMed

Kapranov, Philipp; St Laurent, Georges; Raz, Tal; Ozsolak, Fatih; Reynolds, C Patrick; Sorensen, Poul H B; Reaman, Gregory; Milos, Patrice; Arceci, Robert J; Thompson, John F; Triche, Timothy J

2010-12-21

Discovery that the transcriptional output of the human genome is far more complex than predicted by the current set of protein-coding annotations and that most RNAs produced do not appear to encode proteins has transformed our understanding of genome complexity and suggests new paradigms of genome regulation. However, the fraction of all cellular RNA whose function we do not understand and the fraction of the genome that is utilized to produce that RNA remain controversial. This is not simply a bookkeeping issue because the degree to which this un-annotated transcription is present has important implications with respect to its biologic function and to the general architecture of genome regulation. For example, efforts to elucidate how non-coding RNAs (ncRNAs) regulate genome function will be compromised if that class of RNAs is dismissed as simply 'transcriptional noise'. We show that the relative mass of RNA whose function and/or structure we do not understand (the so called 'dark matter' RNAs), as a proportion of all non-ribosomal, non-mitochondrial human RNA (mt-RNA), can be greater than that of protein-encoding transcripts. This observation is obscured in studies that focus only on polyA-selected RNA, a method that enriches for protein coding RNAs and at the same time discards the vast majority of RNA prior to analysis. We further show the presence of a large number of very long, abundantly-transcribed regions (100's of kb) in intergenic space and further show that expression of these regions is associated with neoplastic transformation. These overlap some regions found previously in normal human embryonic tissues and raises an interesting hypothesis as to the function of these ncRNAs in both early development and neoplastic transformation. We conclude that 'dark matter' RNA can constitute the majority of non-ribosomal, non-mitochondrial-RNA and a significant fraction arises from numerous very long, intergenic transcribed regions that could be involved in neoplastic transformation.

Epitranscriptomic profiling across cell types reveals associations between APOBEC1-mediated RNA editing, gene expression outcomes, and cellular function.

PubMed

Rayon-Estrada, Violeta; Harjanto, Dewi; Hamilton, Claire E; Berchiche, Yamina A; Gantman, Emily Conn; Sakmar, Thomas P; Bulloch, Karen; Gagnidze, Khatuna; Harroch, Sheila; McEwen, Bruce S; Papavasiliou, F Nina

2017-12-12

Epitranscriptomics refers to posttranscriptional alterations on an mRNA sequence that are dynamic and reproducible, and affect gene expression in a similar way to epigenetic modifications. However, the functional relevance of those modifications for the transcript, the cell, and the organism remain poorly understood. Here, we focus on RNA editing and show that Apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-1 (APOBEC1), together with its cofactor RBM47, mediates robust editing in different tissues. The majority of editing events alter the sequence of the 3'UTR of targeted transcripts, and we focus on one cell type (monocytes) and on a small set of highly edited transcripts within it to show that editing alters gene expression by modulating translation (but not RNA stability or localization). We further show that specific cellular processes (phagocytosis and transendothelial migration) are enriched for transcripts that are targets of editing and that editing alters their function. Finally, we survey bone marrow progenitors and demonstrate that common monocyte progenitor cells express high levels of APOBEC1 and are susceptible to loss of the editing enzyme. Overall, APOBEC1-mediated transcriptome diversification is required for the fine-tuning of protein expression in monocytes, suggesting an epitranscriptomic mechanism for the proper maintenance of homeostasis in innate immune cells. Copyright © 2017 the Author(s). Published by PNAS.

MYC Mediates mRNA Cap Methylation of Canonical Wnt/β-catenin Signaling Transcripts by Recruiting CDK7 and RNA Methyltransferase

PubMed Central

Posternak, Valeriya; Ung, Matthew H.; Cheng, Chao; Cole, Michael D.

2016-01-01

MYC is a pleiotropic transcription factor that activates and represses a wide range of target genes and is frequently deregulated in human tumors. While much is known about the role of MYC in transcriptional activation and repression, MYC can also regulate mRNA cap methylation through a mechanism that has remained poorly understood. Here it is reported that MYC enhances mRNA cap methylation of transcripts globally, specifically increasing mRNA cap methylation of genes involved in Wnt/β-catenin signaling. Elevated mRNA cap methylation of Wnt signaling transcripts in response to MYC leads to augmented translational capacity, elevated protein levels, and enhanced Wnt signaling activity. Mechanistic evidence indicates that MYC promotes recruitment of RNA methyltransferase (RNMT) to Wnt signaling gene promoters by enhancing phosphorylation of serine 5 on the RNA Polymerase II Carboxy-Terminal Domain, mediated in part through an interaction between the TIP60 acetyltransferase complex and TFIIH. Implications MYC enhances mRNA cap methylation above and beyond transcriptional induction. PMID:27899423

Human Metapneumovirus Induces Formation of Inclusion Bodies for Efficient Genome Replication and Transcription

PubMed Central

Cifuentes-Muñoz, Nicolás; Branttie, Jean; Slaughter, Kerri Beth

2017-01-01

ABSTRACT Human metapneumovirus (HMPV) causes significant upper and lower respiratory disease in all age groups worldwide. The virus possesses a negative-sense single-stranded RNA genome of approximately 13.3 kb encapsidated by multiple copies of the nucleoprotein (N), giving rise to helical nucleocapsids. In addition, copies of the phosphoprotein (P) and the large RNA polymerase (L) decorate the viral nucleocapsids. After viral attachment, endocytosis, and fusion mediated by the viral glycoproteins, HMPV nucleocapsids are released into the cell cytoplasm. To visualize the subsequent steps of genome transcription and replication, a fluorescence in situ hybridization (FISH) protocol was established to detect different viral RNA subpopulations in infected cells. The FISH probes were specific for detection of HMPV positive-sense RNA (+RNA) and viral genomic RNA (vRNA). Time course analysis of human bronchial epithelial BEAS-2B cells infected with HMPV revealed the formation of inclusion bodies (IBs) from early times postinfection. HMPV IBs were shown to be cytoplasmic sites of active transcription and replication, with the translation of viral proteins being closely associated. Inclusion body formation was consistent with an actin-dependent coalescence of multiple early replicative sites. Time course quantitative reverse transcription-PCR analysis suggested that the coalescence of inclusion bodies is a strategy to efficiently replicate and transcribe the viral genome. These results provide a better understanding of the steps following HMPV entry and have important clinical implications. IMPORTANCE Human metapneumovirus (HMPV) is a recently discovered pathogen that affects human populations of all ages worldwide. Reinfections are common throughout life, but no vaccines or antiviral treatments are currently available. In this work, a spatiotemporal analysis of HMPV replication and transcription in bronchial epithelial cell-derived immortal cells was performed. HMPV was shown to induce the formation of large cytoplasmic granules, named inclusion bodies, for genome replication and transcription. Unlike other cytoplasmic structures, such as stress granules and processing bodies, inclusion bodies are exclusively present in infected cells and contain HMPV RNA and proteins to more efficiently transcribe and replicate the viral genome. Though inclusion body formation is nuanced, it corresponds to a more generalized strategy used by different viruses, including filoviruses and rhabdoviruses, for genome transcription and replication. Thus, an understanding of inclusion body formation is crucial for the discovery of innovative therapeutic targets. PMID:28978704

Human Metapneumovirus Induces Formation of Inclusion Bodies for Efficient Genome Replication and Transcription.

PubMed

Cifuentes-Muñoz, Nicolás; Branttie, Jean; Slaughter, Kerri Beth; Dutch, Rebecca Ellis

2017-12-15

Human metapneumovirus (HMPV) causes significant upper and lower respiratory disease in all age groups worldwide. The virus possesses a negative-sense single-stranded RNA genome of approximately 13.3 kb encapsidated by multiple copies of the nucleoprotein (N), giving rise to helical nucleocapsids. In addition, copies of the phosphoprotein (P) and the large RNA polymerase (L) decorate the viral nucleocapsids. After viral attachment, endocytosis, and fusion mediated by the viral glycoproteins, HMPV nucleocapsids are released into the cell cytoplasm. To visualize the subsequent steps of genome transcription and replication, a fluorescence in situ hybridization (FISH) protocol was established to detect different viral RNA subpopulations in infected cells. The FISH probes were specific for detection of HMPV positive-sense RNA (+RNA) and viral genomic RNA (vRNA). Time course analysis of human bronchial epithelial BEAS-2B cells infected with HMPV revealed the formation of inclusion bodies (IBs) from early times postinfection. HMPV IBs were shown to be cytoplasmic sites of active transcription and replication, with the translation of viral proteins being closely associated. Inclusion body formation was consistent with an actin-dependent coalescence of multiple early replicative sites. Time course quantitative reverse transcription-PCR analysis suggested that the coalescence of inclusion bodies is a strategy to efficiently replicate and transcribe the viral genome. These results provide a better understanding of the steps following HMPV entry and have important clinical implications. IMPORTANCE Human metapneumovirus (HMPV) is a recently discovered pathogen that affects human populations of all ages worldwide. Reinfections are common throughout life, but no vaccines or antiviral treatments are currently available. In this work, a spatiotemporal analysis of HMPV replication and transcription in bronchial epithelial cell-derived immortal cells was performed. HMPV was shown to induce the formation of large cytoplasmic granules, named inclusion bodies, for genome replication and transcription. Unlike other cytoplasmic structures, such as stress granules and processing bodies, inclusion bodies are exclusively present in infected cells and contain HMPV RNA and proteins to more efficiently transcribe and replicate the viral genome. Though inclusion body formation is nuanced, it corresponds to a more generalized strategy used by different viruses, including filoviruses and rhabdoviruses, for genome transcription and replication. Thus, an understanding of inclusion body formation is crucial for the discovery of innovative therapeutic targets. Copyright © 2017 American Society for Microbiology.

Controlling nuclear RNA levels.

PubMed

Schmid, Manfred; Jensen, Torben Heick

2018-05-10

RNA turnover is an integral part of cellular RNA homeostasis and gene expression regulation. Whereas the cytoplasmic control of protein-coding mRNA is often the focus of study, we discuss here the less appreciated role of nuclear RNA decay systems in controlling RNA polymerase II (RNAPII)-derived transcripts. Historically, nuclear RNA degradation was found to be essential for the functionalization of transcripts through their proper maturation. Later, it was discovered to also be an important caretaker of nuclear hygiene by removing aberrant and unwanted transcripts. Recent years have now seen a set of new protein complexes handling a variety of new substrates, revealing functions beyond RNA processing and the decay of non-functional transcripts. This includes an active contribution of nuclear RNA metabolism to the overall cellular control of RNA levels, with mechanistic implications during cellular transitions.

In situ hybridization detection methods for HPV16 E6/E7 mRNA in identifying transcriptionally active HPV infection of oropharyngeal carcinoma: an updating.

PubMed

Volpi, Chiara C; Ciniselli, Chiara M; Gualeni, Ambra V; Plebani, Maddalena; Alfieri, Salvatore; Verderio, Paolo; Locati, Laura; Perrone, Federica; Quattrone, Pasquale; Carbone, Antonino; Pilotti, Silvana; Gloghini, Annunziata

2018-04-01

The aim of this study is to compare 2 in situ hybridization (ISH) detection methods for human papilloma virus (HPV) 16 E6/E7 mRNA, that is, the RNAscope 2.0 High Definition (HD) and the upgraded RNAscope 2.5 HD version. The RNAscope 2.5 HD has recently replaced the RNAscope 2.0 HD detection kit. Therefore, this investigation starts from the need to analytically validate the new mRNA ISH assay and, possibly, to refine the current algorithm for HPV detection in oropharyngeal squamous cell carcinoma with the final goal of applying it to daily laboratory practice. The study was based on HPV status and on generated data, interpreted by a scoring algorithm. The results highlighted that the compared RNAscope HPV tests had a good level of interchangeability and enabled to identify oropharyngeal squamous cell carcinoma that are truly driven by high-risk HPV infection. This was also supported by the comparison of the RNAscope HPV test with HPV E6/E7 mRNA real-time reverse-transcription polymerase chain reaction in a fraction of cases where material for HPV E6/E7 mRNA real-time reverse-transcription polymerase chain reaction was available. Furthermore, the algorithm that associates p16 immunohistochemistry with the identification of HPV mRNA by RNAscope was more effective than the one that associated p16 immunohistochemistry with the identification of HPV DNA by ISH. Copyright © 2017 Elsevier Inc. All rights reserved.

Stress induction of Bm1 RNA in silkworm larvae: SINEs, an unusual class of stress genes

PubMed Central

Kimura, Richard H.; Choudary, Prabhakara V.; Stone, Koni K.; Schmid, Carl W.

2001-01-01

This study surveys the induction of RNA polymerase III (Pol III)–directed expression of short interspersed element (SINE) transcripts by various stresses in an animal model, silkworm larvae. Sublethal heat shock and exposure to several toxic compounds increase the level of Bm1 RNA, the silkworm SINE transcript, while also transiently increasing expression of a well-characterized stress-induced transcript, Hsp70 messenger RNA (mRNA). In certain cases, the Bm1 RNA response coincides with that of Hsp70 mRNA, but more often Bm1 RNA responds later in recovery. Baculovirus infection and exposure to certain toxic compounds increase Bm1 RNA but not Hsp70 mRNA, showing that SINE induction is not necessarily coupled to transcription of this particular heat shock gene. SINEs behave as an additional class of stress-inducible genes in living animals but are unusual as stress genes because of their high copy number, genomic dispersion, and Pol III–directed transcription. PMID:11599568

The role of HPV RNA transcription, immune response-related gene expression and disruptive TP53 mutations in diagnostic and prognostic profiling of head and neck cancer.

PubMed

Wichmann, Gunnar; Rosolowski, Maciej; Krohn, Knut; Kreuz, Markus; Boehm, Andreas; Reiche, Anett; Scharrer, Ulrike; Halama, Dirk; Bertolini, Julia; Bauer, Ulrike; Holzinger, Dana; Pawlita, Michael; Hess, Jochen; Engel, Christoph; Hasenclever, Dirk; Scholz, Markus; Ahnert, Peter; Kirsten, Holger; Hemprich, Alexander; Wittekind, Christian; Herbarth, Olf; Horn, Friedemann; Dietz, Andreas; Loeffler, Markus

2015-12-15

Stratification of head and neck squamous cell carcinomas (HNSCC) based on HPV16 DNA and RNA status, gene expression patterns, and mutated candidate genes may facilitate patient treatment decision. We characterize head and neck squamous cell carcinomas (HNSCC) with different HPV16 DNA and RNA (E6*I) status from 290 consecutively recruited patients by gene expression profiling and targeted sequencing of 50 genes. We show that tumors with transcriptionally inactive HPV16 (DNA+ RNA-) are similar to HPV-negative (DNA-) tumors regarding gene expression and frequency of TP53 mutations (47%, 8/17 and 43%, 72/167, respectively). We also find that an immune response-related gene expression cluster is associated with lymph node metastasis, independent of HPV16 status and that disruptive TP53 mutations are associated with lymph node metastasis in HPV16 DNA- tumors. We validate each of these associations in another large data set. Four gene expression clusters which we identify differ moderately but significantly in overall survival. Our findings underscore the importance of measuring the HPV16 RNA (E6*I) and TP53-mutation status for patient stratification and identify associations of an immune response-related gene expression cluster and TP53 mutations with lymph node metastasis in HNSCC. © 2015 UICC.

Low-level laser irradiation modulates brain-derived neurotrophic factor mRNA transcription through calcium-dependent activation of the ERK/CREB pathway.

PubMed

Yan, Xiaodong; Liu, Juanfang; Zhang, Zhengping; Li, Wenhao; Sun, Siguo; Zhao, Jian; Dong, Xin; Qian, Jixian; Sun, Honghui

2017-01-01

Low-level laser (LLL) irradiation has been reported to promote neuronal differentiation, but the mechanism remains unclear. Brain-derived neurotrophic factor (BDNF) has been confirmed to be one of the most important neurotrophic factors because it is critical for the differentiation and survival of neurons during development. Thus, this study aimed to investigate the effects of LLL irradiation on Bdnf messenger RNA (mRNA) transcription and the molecular pathway involved in LLL-induced Bdnf mRNA transcription in cultured dorsal root ganglion neurons (DRGNs) using Ca 2+ imaging, pharmacological detections, RNA interference, immunocytochemistry assay, Western blot, and qPCR analysis. We show here that LLL induced increases in the [Ca 2+ ] i level, Bdnf mRNA transcription, cAMP-response element-binding protein (CREB) phosphorylation, and extracellular signal-regulated kinase (ERK) phosphorylation, mediated by Ca 2+ release via inositol triphosphate receptor (IP3R)-sensitive calcium (Ca 2+ ) stores. Blockade of Ca 2+ increase suppressed Bdnf mRNA transcription, CREB phosphorylation, and ERK phosphorylation. Downregulation of phosphorylated (p)-CREB reduced Bdnf mRNA transcription triggered by LLL. Furthermore, blockade of ERK using PD98059 inhibitor reduced p-CREB and Bdnf mRNA transcription induced by LLL. Taken together, these findings establish the Ca 2+ -ERK-CREB cascade as a potential signaling pathway involved in LLL-induced Bdnf mRNA transcription. To our knowledge, this is the first report of the mechanisms of Ca 2+ -dependent Bdnf mRNA transcription triggered by LLL. These findings may help further explore the complex molecular signaling networks in LLL-triggered nerve regeneration in vivo and may also provide experimental evidence for the development of LLL for clinical applications.

Heterologous and endogenous U6 snRNA promoters enable CRISPR/Cas9 mediated genome editing in Aspergillus niger.

PubMed

Zheng, Xiaomei; Zheng, Ping; Sun, Jibin; Kun, Zhang; Ma, Yanhe

2018-01-01

U6 promoters have been used for single guide RNA (sgRNA) transcription in the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas9) genome editing system. However, no available U6 promoters have been identified in Aspergillus niger, which is an important industrial platform for organic acid and protein production. Two CRISPR/Cas9 systems established in A. niger have recourse to the RNA polymerase II promoter or in vitro transcription for sgRNA synthesis, but these approaches generally increase cloning efforts and genetic manipulation. The validation of functional RNA polymerase II promoters is therefore an urgent need for A. niger . Here, we developed a novel CRISPR/Cas9 system in A. niger for sgRNA expression, based on one endogenous U6 promoter and two heterologous U6 promoters. The three tested U6 promoters enabled sgRNA transcription and the disruption of the polyketide synthase albA gene in A. niger . Furthermore, this system enabled highly efficient gene insertion at the targeted genome loci in A. niger using donor DNAs with homologous arms as short as 40-bp. This study demonstrated that both heterologous and endogenous U6 promoters were functional for sgRNA expression in A. niger . Based on this result, a novel and simple CRISPR/Cas9 toolbox was established in A. niger, that will benefit future gene functional analysis and genome editing.

Circadian processes in the RNA life cycle.

PubMed

Torres, Manon; Becquet, Denis; Franc, Jean-Louis; François-Bellan, Anne-Marie

2018-05-01

The circadian clock drives daily rhythms of multiple physiological processes, allowing organisms to anticipate and adjust to periodic changes in environmental conditions. These physiological rhythms are associated with robust oscillations in the expression of at least 30% of expressed genes. While the ability for the endogenous timekeeping system to generate a 24-hr cycle is a cell-autonomous mechanism based on negative autoregulatory feedback loops of transcription and translation involving core-clock genes and their protein products, it is now increasingly evident that additional mechanisms also govern the circadian oscillations of clock-controlled genes. Such mechanisms can take place post-transcriptionally during the course of the RNA life cycle. It has been shown that many steps during RNA processing are regulated in a circadian manner, thus contributing to circadian gene expression. These steps include mRNA capping, alternative splicing, changes in splicing efficiency, and changes in RNA stability controlled by the tail length of polyadenylation or the use of alternative polyadenylation sites. RNA transport can also follow a circadian pattern, with a circadian nuclear retention driven by rhythmic expression within the nucleus of particular bodies (the paraspeckles) and circadian export to the cytoplasm driven by rhythmic proteins acting like cargo. Finally, RNA degradation may also follow a circadian pattern through the rhythmic involvement of miRNAs. In this review, we summarize the current knowledge of the post-transcriptional circadian mechanisms known to play a prominent role in shaping circadian gene expression in mammals. This article is categorized under: RNA Processing > Splicing Regulation/Alternative Splicing RNA Processing > RNA Editing and Modification RNA Export and Localization > Nuclear Export/Import. © 2018 Wiley Periodicals, Inc.

Escape of X-linked miRNA genes from meiotic sex chromosome inactivation

PubMed Central

Sosa, Enrique; Flores, Luis; Yan, Wei; McCarrey, John R.

2015-01-01

Past studies have indicated that transcription of all X-linked genes is repressed by meiotic sex chromosome inactivation (MSCI) during the meiotic phase of spermatogenesis in mammals. However, more recent studies have shown an increase in steady-state levels of certain X-linked miRNAs in pachytene spermatocytes, suggesting that either synthesis of these miRNAs increases or that degradation of these miRNAs decreases dramatically in these cells. To distinguish between these possibilities, we performed RNA-FISH to detect nascent transcripts from multiple miRNA genes in various spermatogenic cell types. Our results show definitively that Type I X-linked miRNA genes are subject to MSCI, as are all or most X-linked mRNA genes, whereas Type II and III X-linked miRNA genes escape MSCI by continuing ongoing, active transcription in primary spermatocytes. We corroborated these results by co-localization of RNA-FISH signals with both a corresponding DNA-FISH signal and an immunofluorescence signal for RNA polymerase II. We also found that X-linked miRNA genes that escape MSCI locate non-randomly to the periphery of the XY body, whereas genes that are subject to MSCI remain located within the XY body in pachytene spermatocytes, suggesting that the mechanism of escape of X-linked miRNA genes from MSCI involves their relocation to a position outside of the repressive chromatin domain associated with the XY body. The fact that Type II and III X-linked miRNA genes escape MSCI suggests an immediacy of function of the encoded miRNAs specifically required during the meiotic stages of spermatogenesis. PMID:26395485

Roles of the nucleolus in the CAG RNA-mediated toxicity.

PubMed

Tsoi, Ho; Chan, Ho Yin Edwin

2014-06-01

The nucleolus is a subnuclear compartment within the cell nucleus that serves as the site for ribosomal RNA (rRNA) transcription and the assembly of ribosome subunits. Apart from its classical role in ribosomal biogenesis, a number of cellular regulatory roles have recently been assigned to the nucleolus, including governing the induction of apoptosis. "Nucleolar stress" is a term that is used to describe a signaling pathway through which the nucleolus communicates with other subcellular compartments, including the mitochondria, to induce apoptosis. It is an effective mechanism for eliminating cells that are incapable of performing protein synthesis efficiently due to ribosome biogenesis defects. The down-regulation of rRNA transcription is a common cause of nucleolar function disruption that subsequently triggers nucleolar stress, and has been associated with the pathogenesis of neurological disorders such as spinocerebellar ataxias (SCAs) and Huntington's diseases (HD). This article discusses recent advances in mechanistic studies of how expanded CAG trinucleotide repeat RNA transcripts trigger nucleolar stress in SCAs, HD and other trinucleotide repeat disorders. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease. Copyright © 2013 Elsevier B.V. All rights reserved.

IMP3 Stabilization of WNT5B mRNA Facilitates TAZ Activation in Breast Cancer.

PubMed

Samanta, Sanjoy; Guru, Santosh; Elaimy, Ameer L; Amante, John J; Ou, Jianhong; Yu, Jun; Zhu, Lihua J; Mercurio, Arthur M

2018-05-29

Insulin-like growth factor-2 mRNA-binding protein 3 (IMP3) is an oncofetal protein associated with many aggressive cancers and implicated in the function of breast cancer stem cells (CSCs). The mechanisms involved, however, are poorly understood. We observed that IMP3 facilitates the activation of TAZ, a transcriptional co-activator of Hippo signaling that is necessary for the function of breast CSCs. The mechanism by which IMP3 activates TAZ involves both mRNA stability and transcriptional regulation. IMP3 stabilizes the mRNA of an alternative WNT ligand (WNT5B) indirectly by repressing miR145-5p, which targets WNT5B, resulting in TAZ activation by alternative WNT signaling. IMP3 also facilitates the transcription of SLUG, which is necessary for TAZ nuclear localization and activation, by a mechanism that is also mediated by WNT5B. These results demonstrate that TAZ can be regulated by an mRNA-binding protein and that this regulation involves the integration of Hippo and alternative WNT-signaling pathways. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Direct Regulation of Mitochondrial RNA Synthesis by Thyroid Hormone

PubMed Central

Enríquez, José A.; Fernández-Silva, Patricio; Garrido-Pérez, Nuria; López-Pérez, Manuel J.; Pérez-Martos, Acisclo; Montoya, Julio

1999-01-01

We have analyzed the influence of in vivo treatment and in vitro addition of thyroid hormone on in organello mitochondrial DNA (mtDNA) transcription and, in parallel, on the in organello footprinting patterns at the mtDNA regions involved in the regulation of transcription. We found that thyroid hormone modulates mitochondrial RNA levels and the mRNA/rRNA ratio by influencing the transcriptional rate. In addition, we found conspicuous differences between the mtDNA dimethyl sulfate footprinting patterns of mitochondria derived from euthyroid and hypothyroid rats at the transcription initiation sites but not at the mitochondrial transcription termination factor (mTERF) binding region. Furthermore, direct addition of thyroid hormone to the incubation medium of mitochondria isolated from hypothyroid rats restored the mRNA/rRNA ratio found in euthyroid rats as well as the mtDNA footprinting patterns at the transcription initiation area. Therefore, we conclude that the regulatory effect of thyroid hormone on mitochondrial transcription is partially exerted by a direct influence of the hormone on the mitochondrial transcription machinery. Particularly, the influence on the mRNA/rRNA ratio is achieved by selective modulation of the alternative H-strand transcription initiation sites and does not require the previous activation of nuclear genes. These results provide the first functional demonstration that regulatory signals, such as thyroid hormone, that modify the expression of nuclear genes can also act as primary signals for the transcriptional apparatus of mitochondria. PMID:9858589

A meiotic gene regulatory cascade driven by alternative fates for newly synthesized transcripts

PubMed Central

Cremona, Nicole; Potter, Kristine; Wise, Jo Ann

2011-01-01

To determine the relative importance of transcriptional regulation versus RNA processing and turnover during the transition from proliferation to meiotic differentiation in the fission yeast Schizosaccharomyces pombe, we analyzed temporal profiles and effects of RNA surveillance factor mutants on expression of 32 meiotic genes. A comparison of nascent transcription with steady-state RNA accumulation reveals that the vast majority of these genes show a lag between maximal RNA synthesis and peak RNA accumulation. During meiosis, total RNA levels parallel 3′ processing, which occurs in multiple, temporally distinct waves that peak from 3 to 6 h after meiotic induction. Most early genes and one middle gene, mei4, share a regulatory mechanism in which a specialized RNA surveillance factor targets newly synthesized transcripts for destruction. Mei4p, a member of the forkhead transcription factor family, in turn regulates a host of downstream genes. Remarkably, a spike in transcription is observed for less than one-third of the genes surveyed, and even these show evidence of RNA-level regulation. In aggregate, our findings lead us to propose that a regulatory cascade driven by changes in processing and stability of newly synthesized transcripts operates alongside the well-known transcriptional cascade as fission yeast cells enter meiosis. PMID:21148298

miR-16 and miR-125b are involved in barrier function dysregulation through the modulation of claudin-2 and cingulin expression in the jejunum in IBS with diarrhoea.

PubMed

Martínez, Cristina; Rodiño-Janeiro, Bruno K; Lobo, Beatriz; Stanifer, Megan L; Klaus, Bernd; Granzow, Martin; González-Castro, Ana M; Salvo-Romero, Eloisa; Alonso-Cotoner, Carmen; Pigrau, Marc; Roeth, Ralph; Rappold, Gudrun; Huber, Wolfgang; González-Silos, Rosa; Lorenzo, Justo; de Torres, Inés; Azpiroz, Fernando; Boulant, Steeve; Vicario, María; Niesler, Beate; Santos, Javier

2017-09-01

Micro-RNAs (miRNAs) play a crucial role in controlling intestinal epithelial barrier function partly by modulating the expression of tight junction (TJ) proteins. We have previously shown differential messenger RNA (mRNA) expression correlated with ultrastructural abnormalities of the epithelial barrier in patients with diarrhoea-predominant IBS (IBS-D). However, the participation of miRNAs in these differential mRNA-associated findings remains to be established. Our aims were (1) to identify miRNAs differentially expressed in the small bowel mucosa of patients with IBS-D and (2) to explore putative target genes specifically involved in epithelial barrier function that are controlled by specific dysregulated IBS-D miRNAs. Healthy controls and patients meeting Rome III IBS-D criteria were studied. Intestinal tissue samples were analysed to identify potential candidates by: (a) miRNA-mRNA profiling; (b) miRNA-mRNA pairing analysis to assess the co-expression profile of miRNA-mRNA pairs; (c) pathway analysis and upstream regulator identification; (d) miRNA and target mRNA validation. Candidate miRNA-mRNA pairs were functionally assessed in intestinal epithelial cells. IBS-D samples showed distinct miRNA and mRNA profiles compared with healthy controls. TJ signalling was associated with the IBS-D transcriptional profile. Further validation of selected genes showed consistent upregulation in 75% of genes involved in epithelial barrier function. Bioinformatic analysis of putative miRNA binding sites identified hsa-miR-125b-5p and hsa-miR-16 as regulating expression of the TJ genes CGN (cingulin) and CLDN2 (claudin-2), respectively. Consistently, protein expression of CGN and CLDN2 was upregulated in IBS-D, while the respective targeting miRNAs were downregulated. In addition, bowel dysfunction, perceived stress and depression and number of mast cells correlated with the expression of hsa-miR-125b-5p and hsa-miR-16 and their respective target proteins. Modulation of the intestinal epithelial barrier function in IBS-D involves both transcriptional and post-transcriptional mechanisms. These molecular mechanisms include miRNAs as master regulators in controlling the expression of TJ proteins and are associated with major clinical symptoms. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Mechanical Properties of Transcription

NASA Astrophysics Data System (ADS)

Sevier, Stuart A.; Levine, Herbert

2017-06-01

The mechanical properties of transcription have recently been shown to play a central role in gene expression. However, a full physical characterization of this central biological process is lacking. In this Letter, we introduce a simple description of the basic physical elements of transcription where RNA elongation, RNA polymerase rotation, and DNA supercoiling are coupled. The resulting framework describes the relative amount of RNA polymerase rotation and DNA supercoiling that occurs during RNA elongation. Asymptotic behavior is derived and can be used to experimentally extract unknown mechanical parameters of transcription. Mechanical limits to transcription are incorporated through the addition of a DNA supercoiling-dependent RNA polymerase velocity. This addition can lead to transcriptional stalling and resulting implications for gene expression, chromatin structure and genome organization are discussed.

Maf1 Protein, Repressor of RNA Polymerase III, Indirectly Affects tRNA Processing*

PubMed Central

Karkusiewicz, Iwona; Turowski, Tomasz W.; Graczyk, Damian; Towpik, Joanna; Dhungel, Nripesh; Hopper, Anita K.; Boguta, Magdalena

2011-01-01

Maf1 is negative regulator of RNA polymerase III in yeast. We observed high levels of both primary transcript and end-matured, intron-containing pre-tRNAs in the maf1Δ strain. This pre-tRNA accumulation could be overcome by transcription inhibition, arguing against a direct role of Maf1 in tRNA maturation and suggesting saturation of processing machinery by the increased amounts of primary transcripts. Saturation of the tRNA exportin, Los1, is one reason why end-matured intron-containing pre-tRNAs accumulate in maf1Δ cells. However, it is likely possible that other components of the processing pathway are also limiting when tRNA transcription is increased. According to our model, Maf1-mediated transcription control and nuclear export by Los1 are two major stages of tRNA biosynthesis that are regulated by environmental conditions in a coordinated manner. PMID:21940626

Maf1 protein, repressor of RNA polymerase III, indirectly affects tRNA processing.

PubMed

Karkusiewicz, Iwona; Turowski, Tomasz W; Graczyk, Damian; Towpik, Joanna; Dhungel, Nripesh; Hopper, Anita K; Boguta, Magdalena

2011-11-11

Maf1 is negative regulator of RNA polymerase III in yeast. We observed high levels of both primary transcript and end-matured, intron-containing pre-tRNAs in the maf1Δ strain. This pre-tRNA accumulation could be overcome by transcription inhibition, arguing against a direct role of Maf1 in tRNA maturation and suggesting saturation of processing machinery by the increased amounts of primary transcripts. Saturation of the tRNA exportin, Los1, is one reason why end-matured intron-containing pre-tRNAs accumulate in maf1Δ cells. However, it is likely possible that other components of the processing pathway are also limiting when tRNA transcription is increased. According to our model, Maf1-mediated transcription control and nuclear export by Los1 are two major stages of tRNA biosynthesis that are regulated by environmental conditions in a coordinated manner.

Reduced changes in protein compared to mRNA levels across non-proliferating tissues.

PubMed

Perl, Kobi; Ushakov, Kathy; Pozniak, Yair; Yizhar-Barnea, Ofer; Bhonker, Yoni; Shivatzki, Shaked; Geiger, Tamar; Avraham, Karen B; Shamir, Ron

2017-04-18

The quantitative relations between RNA and protein are fundamental to biology and are still not fully understood. Across taxa, it was demonstrated that the protein-to-mRNA ratio in steady state varies in a direction that lessens the change in protein levels as a result of changes in the transcript abundance. Evidence for this behavior in tissues is sparse. We tested this phenomenon in new data that we produced for the mouse auditory system, and in previously published tissue datasets. A joint analysis of the transcriptome and proteome was performed across four datasets: inner-ear mouse tissues, mouse organ tissues, lymphoblastoid primate samples and human cancer cell lines. We show that the protein levels are more conserved than the mRNA levels in all datasets, and that changes in transcription are associated with translational changes that exert opposite effects on the final protein level, in all tissues except cancer. Finally, we observe that some functions are enriched in the inner ear on the mRNA level but not in protein. We suggest that partial buffering between transcription and translation ensures that proteins can be made rapidly in response to a stimulus. Accounting for the buffering can improve the prediction of protein levels from mRNA levels.

piRNA-guided slicing of transposon transcripts enforces their transcriptional silencing via specifying the nuclear piRNA repertoire.

PubMed

Senti, Kirsten-André; Jurczak, Daniel; Sachidanandam, Ravi; Brennecke, Julius

2015-08-15

PIWI clade Argonaute proteins silence transposon expression in animal gonads. Their target specificity is defined by bound ∼23- to 30-nucleotide (nt) PIWI-interacting RNAs (piRNAs) that are processed from single-stranded precursor transcripts via two distinct pathways. Primary piRNAs are defined by the endonuclease Zucchini, while biogenesis of secondary piRNAs depends on piRNA-guided transcript cleavage and results in piRNA amplification. Here, we analyze the interdependencies between these piRNA biogenesis pathways in developing Drosophila ovaries. We show that secondary piRNA-guided target slicing is the predominant mechanism that specifies transcripts—including those from piRNA clusters—as primary piRNA precursors and defines the spectrum of Piwi-bound piRNAs in germline cells. Post-transcriptional silencing in the cytoplasm therefore enforces nuclear transcriptional target silencing, which ensures the tight suppression of transposons during oogenesis. As target slicing also defines the nuclear piRNA pool during mouse spermatogenesis, our findings uncover an unexpected conceptual similarity between the mouse and fly piRNA pathways. © 2015 Senti et al.; Published by Cold Spring Harbor Laboratory Press.

The cellular growth rate controls overall mRNA turnover, and modulates either transcription or degradation rates of particular gene regulons.

PubMed

García-Martínez, José; Delgado-Ramos, Lidia; Ayala, Guillermo; Pelechano, Vicent; Medina, Daniel A; Carrasco, Fany; González, Ramón; Andrés-León, Eduardo; Steinmetz, Lars; Warringer, Jonas; Chávez, Sebastián; Pérez-Ortín, José E

2016-05-05

We analyzed 80 different genomic experiments, and found a positive correlation between both RNA polymerase II transcription and mRNA degradation with growth rates in yeast. Thus, in spite of the marked variation in mRNA turnover, the total mRNA concentration remained approximately constant. Some genes, however, regulated their mRNA concentration by uncoupling mRNA stability from the transcription rate. Ribosome-related genes modulated their transcription rates to increase mRNA levels under fast growth. In contrast, mitochondria-related and stress-induced genes lowered mRNA levels by reducing mRNA stability or the transcription rate, respectively. We also detected these regulations within the heterogeneity of a wild-type cell population growing in optimal conditions. The transcriptomic analysis of sorted microcolonies confirmed that the growth rate dictates alternative expression programs by modulating transcription and mRNA decay.The regulation of overall mRNA turnover keeps a constant ratio between mRNA decay and the dilution of [mRNA] caused by cellular growth. This regulation minimizes the indiscriminate transmission of mRNAs from mother to daughter cells, and favors the response capacity of the latter to physiological signals and environmental changes. We also conclude that, by uncoupling mRNA synthesis from decay, cells control the mRNA abundance of those gene regulons that characterize fast and slow growth. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

RNA-seq analysis of antibiotic-producing Bacillus subtilis SC-8 in response to signal peptide PapR of Bacillus cereus.

PubMed

Yeo, In-Cheol; Lee, Nam Keun; Yang, Byung Wook; Hahm, Young Tae

2014-01-01

Bacillus subtilis SC-8 produces an antibiotic that has narrow antagonistic activity against bacteria in the Bacillus cereus group. In B. cereus group bacteria, peptide-activating PlcR (PapR) plays a significant role in regulating the transcription of virulence factors. When B. subtilis SC-8 and B. cereus are co-cultured, PapR is assumed to stimulate antibiotic production by B. subtilis SC-8. To better understand the effect of PapR on this interspecies interaction, the global transcriptome profile of B. subtilis SC-8 was analyzed in the presence of PapR. Significant changes were detected in 12.8 % of the total transcripts. Genes related to amino acid transport and metabolism (16.5 %) and transcription (15 %) were mainly upregulated, whereas genes involved in carbohydrate transport and metabolism (12.7 %) were markedly downregulated. The expression of genes related to transcription, including several transcriptional regulators and proteins involved in tRNA biosynthesis, was increased. The expression levels of genes associated with several transport systems, such as antibiotic, cobalt, and iron complex transporters, was also significantly altered. Among the downregulated genes were transcripts associated with spore formation, the subtilosin A gene cluster, and nitrogen metabolism.

PTB-associated splicing factor inhibits IGF-1-induced VEGF upregulation in a mouse model of oxygen-induced retinopathy.

PubMed

Dong, Lijie; Nian, Hong; Shao, Yan; Zhang, Yan; Li, Qiutang; Yi, Yue; Tian, Fang; Li, Wenbo; Zhang, Hong; Zhang, Xiaomin; Wang, Fei; Li, Xiaorong

2015-05-01

Pathological retinal neovascularization, including retinopathy of prematurity and age-related macular degeneration, is the most common cause of blindness worldwide. Insulin-like growth factor-1 (IGF-1) has a direct mitogenic effect on endothelial cells, which is the basis of angiogenesis. Vascular endothelial growth factor (VEGF) activation in response to IGF-1 is well documented; however, the molecular mechanisms responsible for the termination of IGF-1 signaling are still not completely elucidated. Here, we show that the polypyrimidine tract-binding protein-associated splicing factor (PSF) is a potential negative regulator of VEGF expression induced by IGF stimulation. Functional analysis demonstrated that ectopic expression of PSF inhibits IGF-1-stimulated transcriptional activation and mRNA expression of the VEGF gene, whereas knockdown of PSF increased IGF-1-stimulated responses. PSF recruited Hakai to the VEGF transcription complex, resulting in inhibition of IGF-1-mediated transcription. Transfection with Hakai siRNA reversed the PSF-mediated transcriptional repression of VEGF gene transcription. In summary, these results show that PSF can repress the transcriptional activation of VEGF stimulated by IGF-1 via recruitment of the Hakai complex and delineate a novel regulatory mechanism of IGF-1/VEGF signaling that may have implications in the pathogenesis of neovascularization in ocular diseases.

Novel functions of prototype foamy virus Gag glycine- arginine-rich boxes in reverse transcription and particle morphogenesis.

PubMed

Müllers, Erik; Uhlig, Tobias; Stirnnagel, Kristin; Fiebig, Uwe; Zentgraf, Hanswalter; Lindemann, Dirk

2011-02-01

Prototype foamy virus (PFV) Gag lacks the characteristic orthoretroviral Cys-His motifs that are essential for various steps of the orthoretroviral replication cycle, such as RNA packaging, reverse transcription, infectivity, integration, and viral assembly. Instead, it contains three glycine-arginine-rich boxes (GR boxes) in its C terminus that putatively represent a functional equivalent. We used a four-plasmid replication-deficient PFV vector system, with uncoupled RNA genome packaging and structural protein translation, to analyze the effects of deletion and various substitution mutations within each GR box on particle release, particle-associated protein composition, RNA packaging, DNA content, infectivity, particle morphology, and intracellular localization. The degree of viral particle release by all mutants was similar to that of the wild type. Only minimal effects on Pol encapsidation, exogenous reverse transcriptase (RT) activity, and genomic viral RNA packaging were observed. In contrast, particle-associated DNA content and infectivity were drastically reduced for all deletion mutants and were undetectable for all alanine substitution mutants. Furthermore, GR box I mutants had significant changes in particle morphology, and GR box II mutants lacked the typical nuclear localization pattern of PFV Gag. Finally, it could be shown that GR boxes I and III, but not GR box II, can functionally complement each other. It therefore appears that, similar to the orthoretroviral Cys-His motifs, the PFV Gag GR boxes are important for RNA encapsidation, genome reverse transcription, and virion infectivity as well as for particle morphogenesis.

Myonuclear transcription is responsive to mechanical load and DNA content but uncoupled from cell size during hypertrophy

PubMed Central

Kirby, Tyler J.; Patel, Rooshil M.; McClintock, Timothy S.; Dupont-Versteegden, Esther E.; Peterson, Charlotte A.; McCarthy, John J.

2016-01-01

Myofibers increase size and DNA content in response to a hypertrophic stimulus, thus providing a physiological model with which to study how these factors affect global transcription. Using 5-ethynyl uridine (EU) to metabolically label nascent RNA, we measured a sevenfold increase in myofiber transcription during early hypertrophy before a change in cell size and DNA content. The typical increase in myofiber DNA content observed at the later stage of hypertrophy was associated with a significant decrease in the percentage of EU-positive myonuclei; however, when DNA content was held constant by preventing myonuclear accretion via satellite cell depletion, both the number of transcriptionally active myonuclei and the amount of RNA generated by each myonucleus increased. During late hypertrophy, transcription did not scale with cell size, as smaller myofibers (<1000 μm2) demonstrated the highest transcriptional activity. Finally, transcription was primarily responsible for changes in the expression of genes known to regulate myofiber size. These findings show that resident myonuclei possess a significant reserve capacity to up-regulate transcription during hypertrophy and that myofiber transcription is responsive to DNA content but uncoupled from cell size during hypertrophy. PMID:26764089

Transcription regulation by the Mediator complex.

PubMed

Soutourina, Julie

2018-04-01

Alterations in the regulation of gene expression are frequently associated with developmental diseases or cancer. Transcription activation is a key phenomenon in the regulation of gene expression. In all eukaryotes, mediator of RNA polymerase II transcription (Mediator), a large complex with modular organization, is generally required for transcription by RNA polymerase II, and it regulates various steps of this process. The main function of Mediator is to transduce signals from the transcription activators bound to enhancer regions to the transcription machinery, which is assembled at promoters as the preinitiation complex (PIC) to control transcription initiation. Recent functional studies of Mediator with the use of structural biology approaches and functional genomics have revealed new insights into Mediator activity and its regulation during transcription initiation, including how Mediator is recruited to transcription regulatory regions and how it interacts and cooperates with PIC components to assist in PIC assembly. Novel roles of Mediator in the control of gene expression have also been revealed by showing its connection to the nuclear pore and linking Mediator to the regulation of gene positioning in the nuclear space. Clear links between Mediator subunits and disease have also encouraged studies to explore targeting of this complex as a potential therapeutic approach in cancer and fungal infections.

Attenuation of the suppressive activity of cellular splicing factor SRSF3 by Kaposi sarcoma–associated herpesvirus ORF57 protein is required for RNA splicing

PubMed Central

Majerciak, Vladimir; Lu, Mathew; Li, Xiaofan

2014-01-01

Kaposi sarcoma–associated herpesvirus (KSHV) ORF57 is a multifunctional post-transcriptional regulator essential for viral gene expression during KSHV lytic infection. ORF57 requires interactions with various cellular proteins for its function. Here, we identified serine/arginine-rich splicing factor 3 (SRSF3, formerly known as SRp20) as a cellular cofactor involved in ORF57-mediated splicing of KSHV K8β RNA. In the absence of ORF57, SRSF3 binds to a suboptimal K8β intron and inhibits K8β splicing. Knockdown of SRSF3 promotes K8β splicing, mimicking the effect of ORF57. The N-terminal half of ORF57 binds to the RNA recognition motif of SRSF3, which prevents SRSF3 from associating with the K8β intron RNA and therefore attenuates the suppressive effect of SRSF3 on K8β splicing. ORF57 also promotes splicing of heterologous non-KSHV transcripts that are negatively regulated by SRSF3, indicating that the effect of ORF57 on SRSF3 activity is independent of RNA target. SPEN proteins, previously identified as ORF57-interacting partners, suppress ORF57 splicing activity by displacing ORF57 from SRSF3–RNA complexes. In summary, we have identified modulation of SRSF3 activity as the molecular mechanism by which ORF57 promotes RNA splicing. PMID:25234929

Interference of transcription across H-NS binding sites and repression by H-NS.

PubMed

Rangarajan, Aathmaja Anandhi; Schnetz, Karin

2018-05-01

Nucleoid-associated protein H-NS represses transcription by forming extended DNA-H-NS complexes. Repression by H-NS operates mostly at the level of transcription initiation. Less is known about how DNA-H-NS complexes interfere with transcription elongation. In vitro H-NS has been shown to enhance RNA polymerase pausing and to promote Rho-dependent termination, while in vivo inhibition of Rho resulted in a decrease of the genome occupancy by H-NS. Here we show that transcription directed across H-NS binding regions relieves H-NS (and H-NS/StpA) mediated repression of promoters in these regions. Further, we observed a correlation of transcription across the H-NS-bound region and de-repression. The data suggest that the transcribing RNA polymerase is able to remodel the H-NS complex and/or dislodge H-NS from the DNA and thus relieve repression. Such an interference of transcription and H-NS mediated repression may imply that poorly transcribed AT-rich loci are prone to be repressed by H-NS, while efficiently transcribed loci escape repression. © 2018 John Wiley & Sons Ltd.

VirF-Independent Regulation of Shigella virB Transcription is Mediated by the Small RNA RyhB

PubMed Central

Broach, William H.; Egan, Nicholas; Wing, Helen J.; Payne, Shelley M.; Murphy, Erin R.

2012-01-01

Infection of the human host by Shigella species requires the coordinated production of specific Shigella virulence factors, a process mediated largely by the VirF/VirB regulatory cascade. VirF promotes the transcription of virB, a gene encoding the transcriptional activator of several virulence-associated genes. This study reveals that transcription of virB is also regulated by the small RNA RyhB, and importantly, that this regulation is not achieved indirectly via modulation of VirF activity. These data are the first to demonstrate that the regulation of virB transcription can be uncoupled from the master regulator VirF. It is also established that efficient RyhB-dependent regulation of transcription is facilitated by specific nucleic acid sequences within virB. This study not only reveals RyhB-dependent regulation of virB transcription as a novel point of control in the central regulatory circuit modulating Shigella virulence, but also highlights the versatility of RyhB in controlling bacterial gene expression. PMID:22701677

Kaposi's Sarcoma-Associated Herpesvirus mRNA Accumulation in Nuclear Foci Is Influenced by Viral DNA Replication and Viral Noncoding Polyadenylated Nuclear RNA.

PubMed

Vallery, Tenaya K; Withers, Johanna B; Andoh, Joana A; Steitz, Joan A

2018-07-01

Kaposi's sarcoma-associated herpesvirus (KSHV), like other herpesviruses, replicates within the nuclei of its human cell host and hijacks host machinery for expression of its genes. The activities that culminate in viral DNA synthesis and assembly of viral proteins into capsids physically concentrate in nuclear areas termed viral replication compartments. We sought to better understand the spatiotemporal regulation of viral RNAs during the KSHV lytic phase by examining and quantifying the subcellular localization of select viral transcripts. We found that viral mRNAs, as expected, localized to the cytoplasm throughout the lytic phase. However, dependent on active viral DNA replication, viral transcripts also accumulated in the nucleus, often in foci in and around replication compartments, independent of the host shutoff effect. Our data point to involvement of the viral long noncoding polyadenylated nuclear (PAN) RNA in the localization of an early, intronless viral mRNA encoding ORF59-58 to nuclear foci that are associated with replication compartments. IMPORTANCE Late in the lytic phase, mRNAs from Kaposi's sarcoma-associated herpesvirus accumulate in the host cell nucleus near viral replication compartments, centers of viral DNA synthesis and virion production. This work contributes spatiotemporal data on herpesviral mRNAs within the lytic host cell and suggests a mechanism for viral RNA accumulation. Our findings indicate that the mechanism is independent of the host shutoff effect and splicing but dependent on active viral DNA synthesis and in part on the viral noncoding RNA, PAN RNA. PAN RNA is essential for the viral life cycle, and its contribution to the nuclear accumulation of viral messages may facilitate propagation of the virus. Copyright © 2018 American Society for Microbiology.

A Herpesvirus Protein Selectively Inhibits Cellular mRNA Nuclear Export.

PubMed

Gong, Danyang; Kim, Yong Hoon; Xiao, Yuchen; Du, Yushen; Xie, Yafang; Lee, Kevin K; Feng, Jun; Farhat, Nisar; Zhao, Dawei; Shu, Sara; Dai, Xinghong; Chanda, Sumit K; Rana, Tariq M; Krogan, Nevan J; Sun, Ren; Wu, Ting-Ting

2016-11-09

Nuclear mRNA export is highly regulated to ensure accurate cellular gene expression. Viral inhibition of cellular mRNA export can enhance viral access to the cellular translation machinery and prevent anti-viral protein production but is generally thought to be nonselective. We report that ORF10 of Kaposi's sarcoma-associated herpesvirus (KSHV), a nuclear DNA virus, inhibits mRNA export in a transcript-selective manner to control cellular gene expression. Nuclear export inhibition by ORF10 requires an interaction with an RNA export factor, Rae1. Genome-wide analysis reveals a subset of cellular mRNAs whose nuclear export is blocked by ORF10 with the 3' UTRs of ORF10-targeted transcripts conferring sensitivity to export inhibition. The ORF10-Rae1 interaction is important for the virus to express viral genes and produce infectious virions. These results suggest that a nuclear DNA virus can selectively interfere with RNA export to restrict host gene expression for optimal replication. Published by Elsevier Inc.

Destabilization of B2 RNA by EZH2 activates the stress response

PubMed Central

Zovoilis, Athanasios; Cifuentes-Rojas, Catherine; Chu, Hsueh-Ping; Hernandez, Alfredo J.; Lee, Jeannie T.

2017-01-01

SUMMARY More than 98% of the mammalian genome is noncoding and interspersed transposable elements account for ~50% of noncoding space. Here, we demonstrate that a specific interaction between the Polycomb protein, EZH2, and RNA made from B2 SINE retrotransposons controls stress-responsive genes in mouse cells. In the heat shock model, B2 RNA binds stress genes and suppresses their transcription. Upon stress, EZH2 is recruited and triggers cleavage of B2 RNA. B2 degradation in turn upregulates stress genes. Evidence indicates that B2 RNA operates as “speed bump” against advancement of RNA Polymerase II, and temperature stress releases the brakes on transcriptional elongation. These data attribute a new function to EZH2 that is independent of its histone methyltransferase activity and reconcile how EZH2 can be associated with both gene repression and activation. Our study reveals that EZH2 and B2 together control activation of a large network of genes involved in thermal stress. PMID:27984727

Cell cycle-dependent regulation of Aurora kinase B mRNA by the Microprocessor complex.

PubMed

Jung, Eunsun; Seong, Youngmo; Seo, Jae Hong; Kwon, Young-Soo; Song, Hoseok

2014-03-28

Aurora kinase B regulates the segregation of chromosomes and the spindle checkpoint during mitosis. In this study, we showed that the Microprocessor complex, which is responsible for the processing of the primary transcripts during the generation of microRNAs, destabilizes the mRNA of Aurora kinase B in human cells. The Microprocessor-mediated cleavage kept Aurora kinase B at a low level and prevented premature entrance into mitosis. The cleavage was reduced during mitosis leading to the accumulation of Aurora kinase B mRNA and protein. In addition to Aurora kinase B mRNA, the processing of other primary transcripts of miRNAs were also decreased during mitosis. We found that the cleavage was dependent on an RNA helicase, DDX5, and the association of DDX5 and DDX17 with the Microprocessor was reduced during mitosis. Thus, we propose a novel mechanism by which the Microprocessor complex regulates stability of Aurora kinase B mRNA and cell cycle progression. Copyright © 2014 Elsevier Inc. All rights reserved.

Isolation and identification of gene-specific microRNAs.

PubMed

Lin, Shi-Lung; Chang, Donald C; Ying, Shao-Yao

2006-01-01

Prediction of microRNA (miRNA) candidates using computer programming has identified hundreds and hundreds of genomic hairpin sequences, of which, the functions remain to be determined. Because direct transfection of hairpin-like miRNA precursors (pre)-miRNAs in mammalian cells is not always sufficient to trigger effective RNA-induced gene-silencing complex (RISC) assembly, a key step for RNA interference (RNAi)-related gene silencing, we developed an intronic miRNA-expressing system to overcome this problem, and successfully increased the efficiency and effectiveness of miRNA-associated RNAi induction in vitro and in vivo. By insertion of a hairpin-like pre-miRNA structure into the intron region of a gene, this intronic miRNA biogenesis system has been found to depend on a coupled interaction of nascent precursor messenger RNA transcription and intron excision within a specific nuclear region proximal to genomic perichromatin fibrils. The intronic miRNA was transcribed by RNA type II polymerases, coexpressed with a primary gene transcript, and excised out of its encoding gene transcript by intracellular RNA splicing and processing mechanisms. Currently, some ribonuclease III endonucleases have been found to be involved in the processing of spliced introns and probably facilitating the intronic miRNA maturation. Using this miRNA-expressing system, we have shown for the first time that the intron-derived miRNAs were able to induce strong RNAi effects in not only human and mouse cells but also zebrafish, chicken embryos, and adult mice. Based on the strand complementarity between the designed miRNA and its target gene sequence, we have also developed a miRNA isolation protocol to purify and identify the mature miRNAs generated by the intronic miRNA-expressing system. Several intronic miRNA identities and structures are currently confirmed to be active in vitro and in vivo. According to this proof- of-principle method, we now have the knowledge to design pre-miRNA inserts that are more efficient and effective for the intronic miRNA-expressing system.

A dsRNA-binding protein MdDRB1 associated with miRNA biogenesis modifies adventitious rooting and tree architecture in apple.

PubMed

You, Chun-Xiang; Zhao, Qiang; Wang, Xiao-Fei; Xie, Xing-Bin; Feng, Xiao-Ming; Zhao, Ling-Ling; Shu, Huai-Rui; Hao, Yu-Jin

2014-02-01

Although numerous miRNAs have been already isolated from fruit trees, knowledge about miRNA biogenesis is largely unknown in fruit trees. Double-strand RNA-binding (DRB) protein plays an important role in miRNA processing and maturation; however, its role in the regulation of economically important traits is not clear yet in fruit trees. EST blast and RACE amplification were performed to isolate apple MdDRB1 gene. Following expression analysis, RNA binding and protein interaction assays, MdDRB1 was transformed into apple callus and in vitro tissue cultures to characterize the functions of MdDRB1 in miRNA biogenesis, adventitious rooting, leaf development and tree growth habit. MdDRB1 contained two highly conserved DRB domains. Its transcripts existed in all tissues tested and are induced by hormones. It bound to double-strand RNAs and interacted with AtDCL1 (Dicer-Like 1) and MdDCL1. Chip assay indicated its role in miRNA biogenesis. Transgenic analysis showed that MdDRB1 controls adventitious rooting, leaf curvature and tree architecture by modulating the accumulation of miRNAs and the transcript levels of miRNA target genes. Our results demonstrated that MdDRB1 functions in the miRNA biogenesis in a conserved way and that it is a master regulator in the formation of economically important traits in fruit trees. © 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

LEDGF/p75 interacts with mRNA splicing factors and targets HIV-1 integration to highly spliced genes

PubMed Central

Singh, Parmit Kumar; Plumb, Matthew R.; Ferris, Andrea L.; Iben, James R.; Wu, Xiaolin; Fadel, Hind J.; Luke, Brian T.; Esnault, Caroline; Poeschla, Eric M.; Hughes, Stephen H.; Kvaratskhelia, Mamuka; Levin, Henry L.

2015-01-01

The host chromatin-binding factor LEDGF/p75 interacts with HIV-1 integrase and directs integration to active transcription units. To understand how LEDGF/p75 recognizes transcription units, we sequenced 1 million HIV-1 integration sites isolated from cultured HEK293T cells. Analysis of integration sites showed that cancer genes were preferentially targeted, raising concerns about using lentivirus vectors for gene therapy. Additional analysis led to the discovery that introns and alternative splicing contributed significantly to integration site selection. These correlations were independent of transcription levels, size of transcription units, and length of the introns. Multivariate analysis with five parameters previously found to predict integration sites showed that intron density is the strongest predictor of integration density in transcription units. Analysis of previously published HIV-1 integration site data showed that integration density in transcription units in mouse embryonic fibroblasts also correlated strongly with intron number, and this correlation was absent in cells lacking LEDGF. Affinity purification showed that LEDGF/p75 is associated with a number of splicing factors, and RNA sequencing (RNA-seq) analysis of HEK293T cells lacking LEDGF/p75 or the LEDGF/p75 integrase-binding domain (IBD) showed that LEDGF/p75 contributes to splicing patterns in half of the transcription units that have alternative isoforms. Thus, LEDGF/p75 interacts with splicing factors, contributes to exon choice, and directs HIV-1 integration to transcription units that are highly spliced. PMID:26545813

A Molecular Titration System Coordinates Ribosomal Protein Gene Transcription with Ribosomal RNA Synthesis.

PubMed

Albert, Benjamin; Knight, Britta; Merwin, Jason; Martin, Victoria; Ottoz, Diana; Gloor, Yvonne; Bruzzone, Maria Jessica; Rudner, Adam; Shore, David

2016-11-17

Cell growth potential is determined by the rate of ribosome biogenesis, a complex process that requires massive and coordinated transcriptional output. In the yeast Saccharomyces cerevisiae, ribosome biogenesis is highly regulated at the transcriptional level. Although evidence for a system that coordinates ribosomal RNA (rRNA) and ribosomal protein gene (RPG) transcription has been described, the molecular mechanisms remain poorly understood. Here we show that an interaction between the RPG transcriptional activator Ifh1 and the rRNA processing factor Utp22 serves to coordinate RPG transcription with that of rRNA. We demonstrate that Ifh1 is rapidly released from RPG promoters by a Utp22-independent mechanism following growth inhibition, but that its long-term dissociation requires Utp22. We present evidence that RNA polymerase I activity inhibits the ability of Utp22 to titrate Ifh1 from RPG promoters and propose that a dynamic Ifh1-Utp22 interaction fine-tunes RPG expression to coordinate RPG and rRNA transcription. Copyright © 2016 Elsevier Inc. All rights reserved.

E6-associated transcription patterns in human papilloma virus 16-positive cervical tissues.

PubMed

Lin, Kezhi; Lu, Xulian; Chen, Jun; Zou, Ruanmin; Zhang, Lifang; Xue, Xiangyang

2015-01-01

The change in transcription pattern induced by post-transcriptional RNA splicing is an important mechanism in the regulation of the early gene expression of human papilloma virus (HPV). The present study was conducted to establish a method to specifically amplify HPV-16 E6-associated transcripts. The E6-related transcripts from 63 HPV-16-positive cervical tumor tissue samples were amplified, consisting of eight cases of low-risk intraepithelial lesions, 38 cases of high-risk intraepithelial lesions and 17 cases of cervical cancer (CxCa). The appropriate amplified segments were recovered following agarose gel electrophoresis, and subjected to further sequencing and sequence alignment analysis. Six groups of E6 transcription patterns were identified from HPV-16-positive cervical tumor tissue, including five newly-discovered transcripts. Different HPV-16 E6-associated transcription patterns were detected during the development of CxCa. Over the course of the progression of the low-grade squamous intraepithelial lesions to CxCa, the specific HPV-16 E6-associated transcription patterns and the dominant transcripts were all different. As indicated by this study, the transcription pattern of the E6 early gene of HPV-16 was closely associated with the stages of cervical carcinogenesis, and may also be involved in the development of CxCa.

Role of mRNA Methylation in Prostate Cancer

DTIC Science & Technology

2015-02-01

position of adenosine (m6A) is a post-transcriptional modification of mRNA. However, little is known regarding the biological meanings of this epigenetic ...its level is altered in various cancer cell lines. FTO, the fat mass and obesity associated gene, was recently shown as an m6A demethylase. FTO gene...mRNA. However, little is known regarding the biological meanings of this epigenetic regulation of mRNA. Recent technological advances have made it

Heat Shock Response in Yeast Involves Changes in Both Transcription Rates and mRNA Stabilities

PubMed Central

Castells-Roca, Laia; García-Martínez, José; Moreno, Joaquín; Herrero, Enrique; Bellí, Gemma; Pérez-Ortín, José E.

2011-01-01

We have analyzed the heat stress response in the yeast Saccharomyces cerevisiae by determining mRNA levels and transcription rates for the whole transcriptome after a shift from 25°C to 37°C. Using an established mathematical algorithm, theoretical mRNA decay rates have also been calculated from the experimental data. We have verified the mathematical predictions for selected genes by determining their mRNA decay rates at different times during heat stress response using the regulatable tetO promoter. This study indicates that the yeast response to heat shock is not only due to changes in transcription rates, but also to changes in the mRNA stabilities. mRNA stability is affected in 62% of the yeast genes and it is particularly important in shaping the mRNA profile of the genes belonging to the environmental stress response. In most cases, changes in transcription rates and mRNA stabilities are homodirectional for both parameters, although some interesting cases of antagonist behavior are found. The statistical analysis of gene targets and sequence motifs within the clusters of genes with similar behaviors shows that both transcriptional and post-transcriptional regulons apparently contribute to the general heat stress response by means of transcriptional factors and RNA binding proteins. PMID:21364882

Effective reduction of the interleukin-1β transcript in osteoarthritis-prone guinea pig chondrocytes via short hairpin RNA mediated RNA interference influences gene expression of mediators implicated in disease pathogenesis.

PubMed

Santangelo, K S; Bertone, A L

2011-12-01

To ascertain a viral vector-based short hairpin RNA (shRNA) capable of reducing the interleukin-1β (IL-1β) transcript in osteoarthritis (OA)-prone chondrocytes and detect corresponding changes in the expression patterns of several critical disease mediators. Cultured chondrocytes from 2-month-old Hartley guinea pigs were screened for reduction of the IL-1β transcript following plasmid-based delivery of U6-driven shRNA sequences. A successful plasmid/shRNA knockdown combination was identified and used to construct an adeno-associated virus serotype 5 (AAV5) vector for further evaluation. Relative real-time reverse transcription polymerase chain reaction (RT-PCR) was used to quantify in vitro transcript changes of IL-1β and an additional nine genes following transduction with this targeting knockdown vector. To validate in vitro findings, this AAV5 vector was injected into one knee, while either an equivalent volume of saline vehicle (three animals) or non-targeting control vector (three animals) were injected into opposite knees. Fold differences and subsequent percent gene expression levels relative to control groups were calculated using the comparative CT (2(-ΔΔCT)) method. Statistically significant decreases in IL-1β expression were achieved by the targeting knockdown vector relative to both the mock-transduced control and non-targeting vector control groups in vitro. Transcript levels of anabolic transforming growth factor-β (TGF-β) were significantly increased by use of this targeting knockdown vector. Transduction with this targeting AAV5 vector also significantly decreased the transcript levels of key inflammatory cytokines [tumor necrosis factor-α (TNF-α), IL-2, IL-8, and IL-12] and catabolic agents [matrix metalloproteinase (MMP)13, MMP2, interferon-γ (IFN-γ), and inducible nitrous oxide synthase (iNOS)] relative to both mock-transduced and non-targeting vector control groups. In vivo application of this targeting knockdown vector resulted in a >50% reduction (P=0.0045) or >90% (P=0.0001) of the IL-1β transcript relative to vehicle-only or non-targeting vector control exposed cartilage, respectively. Successful reduction of the IL-1β transcript was achieved via RNA interference (RNAi) techniques. Importantly, this alteration significantly influenced the transcript levels of several major players involved in OA pathogenesis in the direction of disease modification. Investigations to characterize additional gene expression changes influenced by targeting knockdown AAV5 vector-based diminution of the IL-1β transcript in vivo are warranted. Copyright © 2011 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

RNA G-quadruplexes cause eIF4A-dependent oncogene translation in cancer

NASA Astrophysics Data System (ADS)

Wolfe, Andrew L.; Singh, Kamini; Zhong, Yi; Drewe, Philipp; Rajasekhar, Vinagolu K.; Sanghvi, Viraj R.; Mavrakis, Konstantinos J.; Jiang, Man; Roderick, Justine E.; van der Meulen, Joni; Schatz, Jonathan H.; Rodrigo, Christina M.; Zhao, Chunying; Rondou, Pieter; de Stanchina, Elisa; Teruya-Feldstein, Julie; Kelliher, Michelle A.; Speleman, Frank; Porco, John A.; Pelletier, Jerry; Rätsch, Gunnar; Wendel, Hans-Guido

2014-09-01

The translational control of oncoprotein expression is implicated in many cancers. Here we report an eIF4A RNA helicase-dependent mechanism of translational control that contributes to oncogenesis and underlies the anticancer effects of silvestrol and related compounds. For example, eIF4A promotes T-cell acute lymphoblastic leukaemia development in vivo and is required for leukaemia maintenance. Accordingly, inhibition of eIF4A with silvestrol has powerful therapeutic effects against murine and human leukaemic cells in vitro and in vivo. We use transcriptome-scale ribosome footprinting to identify the hallmarks of eIF4A-dependent transcripts. These include 5' untranslated region (UTR) sequences such as the 12-nucleotide guanine quartet (CGG)4 motif that can form RNA G-quadruplex structures. Notably, among the most eIF4A-dependent and silvestrol-sensitive transcripts are a number of oncogenes, superenhancer-associated transcription factors, and epigenetic regulators. Hence, the 5' UTRs of select cancer genes harbour a targetable requirement for the eIF4A RNA helicase.

The homologous recombination machinery modulates the formation of RNA–DNA hybrids and associated chromosome instability

PubMed Central

Wahba, Lamia; Gore, Steven K; Koshland, Douglas

2013-01-01

Genome instability in yeast and mammals is caused by RNA–DNA hybrids that form as a result of defects in different aspects of RNA biogenesis. We report that in yeast mutants defective for transcription repression and RNA degradation, hybrid formation requires Rad51p and Rad52p. These proteins normally promote DNA–DNA strand exchange in homologous recombination. We suggest they also directly promote the DNA–RNA strand exchange necessary for hybrid formation since we observed accumulation of Rad51p at a model hybrid-forming locus. Furthermore, we provide evidence that Rad51p mediates hybridization of transcripts to homologous chromosomal loci distinct from their site of synthesis. This hybrid formation in trans amplifies the genome-destabilizing potential of RNA and broadens the exclusive co-transcriptional models that pervade the field. The deleterious hybrid-forming activity of Rad51p is counteracted by Srs2p, a known Rad51p antagonist. Thus Srs2p serves as a novel anti-hybrid mechanism in vivo. DOI: http://dx.doi.org/10.7554/eLife.00505.001 PMID:23795288

SMN control of RNP assembly: from post-transcriptional gene regulation to motor neuron disease

PubMed Central

Li, Darrick K.; Tisdale, Sarah; Lotti, Francesco; Pellizzoni, Livio

2014-01-01

At the post-transcriptional level, expression of protein-coding genes is controlled by a series of RNA regulatory events including nuclear processing of primary transcripts, transport of mature mRNAs to specific cellular compartments, translation and ultimately, turnover. These processes are orchestrated through the dynamic association of mRNAs with RNA binding proteins and ribonucleoprotein (RNP) complexes. Accurate formation of RNPs in vivo is fundamentally important to cellular development and function, and its impairment often leads to human disease. The survival motor neuron (SMN) protein is key to this biological paradigm: SMN is essential for the biogenesis of various RNPs that function in mRNA processing, and genetic mutations leading to SMN deficiency cause the neurodegenerative disease spinal muscular atrophy. Here we review the expanding role of SMN in the regulation of gene expression through its multiple functions in RNP assembly. We discuss advances in our understanding of SMN activity as a chaperone of RNPs and how disruption of SMN-dependent RNA pathways can cause motor neuron disease. PMID:24769255

Genome-wide mapping of infection-induced SINE RNAs reveals a role in selective mRNA export.

PubMed

Karijolich, John; Zhao, Yang; Alla, Ravi; Glaunsinger, Britt

2017-06-02

Short interspersed nuclear elements (SINEs) are retrotransposons evolutionarily derived from endogenous RNA Polymerase III RNAs. Though SINE elements have undergone exaptation into gene regulatory elements, how transcribed SINE RNA impacts transcriptional and post-transcriptional regulation is largely unknown. This is partly due to a lack of information regarding which of the loci have transcriptional potential. Here, we present an approach (short interspersed nuclear element sequencing, SINE-seq), which selectively profiles RNA Polymerase III-derived SINE RNA, thereby identifying transcriptionally active SINE loci. Applying SINE-seq to monitor murine B2 SINE expression during a gammaherpesvirus infection revealed transcription from 28 270 SINE loci, with ∼50% of active SINE elements residing within annotated RNA Polymerase II loci. Furthermore, B2 RNA can form intermolecular RNA-RNA interactions with complementary mRNAs, leading to nuclear retention of the targeted mRNA via a mechanism involving p54nrb. These findings illuminate a pathway for the selective regulation of mRNA export during stress via retrotransposon activation. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

The maize stripe virus major noncapsid protein messenger RNA transcripts contain heterogeneous leader sequences at their 5' termini.

PubMed

Huiet, L; Feldstein, P A; Tsai, J H; Falk, B W

1993-12-01

Primer extension analyses and a PCR-based cloning strategy were used to identify and characterize 5' nucleotide sequences on the maize stripe virus (MStV) RNA4 mRNA transcripts encoding the major noncapsid protein (NCP). Direct RNA sequence analysis by primer extension showed that the NCP mRNA transcripts had 10-15 nucleotides beyond the 5' terminus of the MStV RNA4 nucleotide sequence. MStV genomic RNAs isolated from ribonucleoprotein particles (RNPs) lacked the additional 5' nucleotides. cDNA clones representing the 5' region of the mRNA transcripts were constructed, and the nucleotide sequences of the 5' regions were determined for 16 clones. Each was found to have a distinct 10-15 nucleotide sequence immediately 5' of the MStV RNA4 sequence. Eleven of 16 clones had the correct MStV RNA4 5' nucleotide sequence, while five showed minor variations at or near the 5' most MStV RNA4 nucleotide. These characteristics show strong similarities to other viral mRNA transcripts which are synthesized by cap snatching.

Hepcidin suppression in β-thalassemia is associated with the down-regulation of atonal homolog 8.

PubMed

Upanan, Supranee; McKie, Andrew T; Latunde-Dada, Gladys O; Roytrakul, Sittiruk; Uthaipibull, Chairat; Pothacharoen, Peraphan; Kongtawelert, Prachya; Fucharoen, Suthat; Srichairatanakool, Somdet

2017-08-01

Atonal homolog 8 (ATOH8) is defined as a positive regulator of hepcidin transcription, which links erythropoietic activity with iron-sensing molecules. In the present study, we investigated the association between hepcidin and ATOH8 expression in β-thalassemia. We found that inhibition of hepcidin expression in β-thalassemia is correlated with reduced ATOH8 expression. Hepatic hepcidin 1 (Hamp1) and Atoh8 mRNA expression were down-regulated in β-thalassemic mice. Hepcidin (HAMP) and ATOH8 mRNA expression were consistently suppressed in Huh7 cells cultured in medium supplemented with β-thalassemia patient serum. The Huh7 cells, which were transfected with ATOH8-FLAG expression plasmid and cultured in the supplemented medium, exhibited increased levels of ATOH8 mRNA, ATOH8-FLAG protein, pSMAD1,5,8, and HAMP mRNA. Interestingly, over-expression of ATOH8 reversed the effects of hepcidin suppression induced by the β-thalassemia patient sera. In conclusion, hepcidin suppression in β-thalassemia is associated with the down-regulation of ATOH8 in response to anemia. We, therefore, suggest that ATOH8 is an important transcriptional regulator of hepcidin in β-thalassemia.

The Status of Exon Skipping as a Therapeutic Approach to Duchenne Muscular Dystrophy

PubMed Central

Lu, Qi-Long; Yokota, Toshifumi; Takeda, Shin'ichi; Garcia, Luis; Muntoni, Francesco; Partridge, Terence

2011-01-01

Duchenne muscular dystrophy (DMD) is associated with mutations in the dystrophin gene that disrupt the open reading frame whereas the milder Becker's form is associated with mutations which leave an in-frame mRNA transcript that can be translated into a protein that includes the N- and C- terminal functional domains. It has been shown that by excluding specific exons at, or adjacent to, frame-shifting mutations, open reading frame can be restored to an out-of-frame mRNA, leading to the production of a partially functional Becker-like dystrophin protein. Such targeted exclusion can be achieved by administration of oligonucleotides that are complementary to sequences that are crucial to normal splicing of the exon into the transcript. This principle has been validated in mouse and canine models of DMD with a number of variants of oligonucleotide analogue chemistries and by transduction with adeno-associated virus (AAV)-small nuclear RNA (snRNA) reagents encoding the antisense sequence. Two different oligonucleotide agents are now being investigated in human trials for splicing out of exon 51 with some early indications of success at the biochemical level. PMID:20978473

Protection of germline gene expression by the C. elegans Argonaute CSR-1.

PubMed

Wedeles, Christopher J; Wu, Monica Z; Claycomb, Julie M

2013-12-23

In Caenorhabditis elegans, the Piwi-interacting small RNA (piRNA)-mediated germline surveillance system encodes more than 30,000 unique 21-nucleotide piRNAs, which silence a variety of foreign nucleic acids. What mechanisms allow endogenous germline-expressed transcripts to evade silencing by the piRNA pathway? One likely candidate in a protective mechanism is the Argonaute CSR-1, which interacts with 22G-small RNAs that are antisense to nearly all germline-expressed genes. Here, we use an in vivo RNA tethering assay to demonstrate that the recruitment of CSR-1 to a transcript licenses expression of the transcript, protecting it from piRNA-mediated silencing. Licensing occurs mainly at the level of transcription, as we observe changes in pre-mRNA levels consistent with transcriptional activation when CSR-1 is tethered. Furthermore, the recruitment of CSR-1 to a previously silenced locus transcriptionally activates its expression. Together, these results demonstrate a rare positive role for an endogenous Argonaute pathway in heritably licensing and protecting germline transcripts.

Identification of MicroRNA Targets of Capsicum spp. Using MiRTrans—a Trans-Omics Approach

PubMed Central

Zhang, Lu; Qin, Cheng; Mei, Junpu; Chen, Xiaocui; Wu, Zhiming; Luo, Xirong; Cheng, Jiaowen; Tang, Xiangqun; Hu, Kailin; Li, Shuai C.

2017-01-01

The microRNA (miRNA) can regulate the transcripts that are involved in eukaryotic cell proliferation, differentiation, and metabolism. Especially for plants, our understanding of miRNA targets, is still limited. Early attempts of prediction on sequence alignments have been plagued by enormous false positives. It is helpful to improve target prediction specificity by incorporating the other data sources such as the dependency between miRNA and transcript expression or even cleaved transcripts by miRNA regulations, which are referred to as trans-omics data. In this paper, we developed MiRTrans (Prediction of MiRNA targets by Trans-omics data) to explore miRNA targets by incorporating miRNA sequencing, transcriptome sequencing, and degradome sequencing. MiRTrans consisted of three major steps. First, the target transcripts of miRNAs were predicted by scrutinizing their sequence characteristics and collected as an initial potential targets pool. Second, false positive targets were eliminated if the expression of miRNA and its targets were weakly correlated by lasso regression. Third, degradome sequencing was utilized to capture the miRNA targets by examining the cleaved transcripts that regulated by miRNAs. Finally, the predicted targets from the second and third step were combined by Fisher's combination test. MiRTrans was applied to identify the miRNA targets for Capsicum spp. (i.e., pepper). It can generate more functional miRNA targets than sequence-based predictions by evaluating functional enrichment. MiRTrans identified 58 miRNA-transcript pairs with high confidence from 18 miRNA families conserved in eudicots. Most of these targets were transcription factors; this lent support to the role of miRNA as key regulator in pepper. To our best knowledge, this work is the first attempt to investigate the miRNA targets of pepper, as well as their regulatory networks. Surprisingly, only a small proportion of miRNA-transcript pairs were shared between degradome sequencing and expression dependency predictions, suggesting that miRNA targets predicted by a single technology alone may be prone to report false negatives. PMID:28443105

The NBS1-Treacle complex controls ribosomal RNA transcription in response to DNA damage

PubMed Central

Larsen, Dorthe H; Hari, Flurina; Clapperton, Julie A; Gwerder, Myriam; Gutsche, Katrin; Altmeyer, Matthias; Jungmichel, Stephanie; Toledo, Luis I; Fink, Daniel; Rask, Maj-Britt; Grøfte, Merete; Lukas, Claudia; Nielsen, Michael L; Smerdon, Stephen J; Lukas, Jiri; Stucki, Manuel

2016-01-01

Chromosome breakage elicits transient silencing of ribosomal RNA synthesis, but the mechanisms involved remained elusive. Here we discover an in-trans signaling mechanism that triggers pan-nuclear silencing of rRNA transcription in response to DNA damage. This is associated with transient recruitment of the Nijmegen breakage syndrome protein 1 (NBS1), a central regulator of DNA damage responses, into the nucleoli. We further identified TCOF1-Treacle, a nucleolar factor implicated in ribosome biogenesis and mutated in Treacher Collins syndrome, as an interaction partner of NBS1, and demonstrate that NBS1 translocation and accumulation in the nucleoli is Treacle-dependent. Finally, we provide evidence that Treacle-mediated NBS1 recruitment into the nucleoli regulates rRNA silencing in-trans in the presence of distant chromosome breaks. PMID:25064736

The NBS1-Treacle complex controls ribosomal RNA transcription in response to DNA damage.

PubMed

Larsen, Dorthe H; Hari, Flurina; Clapperton, Julie A; Gwerder, Myriam; Gutsche, Katrin; Altmeyer, Matthias; Jungmichel, Stephanie; Toledo, Luis I; Fink, Daniel; Rask, Maj-Britt; Grøfte, Merete; Lukas, Claudia; Nielsen, Michael L; Smerdon, Stephen J; Lukas, Jiri; Stucki, Manuel

2014-08-01

Chromosome breakage elicits transient silencing of ribosomal RNA synthesis, but the mechanisms involved remained elusive. Here we discover an in trans signalling mechanism that triggers pan-nuclear silencing of rRNA transcription in response to DNA damage. This is associated with transient recruitment of the Nijmegen breakage syndrome protein 1 (NBS1), a central regulator of DNA damage responses, into the nucleoli. We further identify TCOF1 (also known as Treacle), a nucleolar factor implicated in ribosome biogenesis and mutated in Treacher Collins syndrome, as an interaction partner of NBS1, and demonstrate that NBS1 translocation and accumulation in the nucleoli is Treacle dependent. Finally, we provide evidence that Treacle-mediated NBS1 recruitment into the nucleoli regulates rRNA silencing in trans in the presence of distant chromosome breaks.

Global assessment of small RNAs reveals a non-coding transcript involved in biofilm formation and attachment in Acinetobacter baumannii ATCC 17978

PubMed Central

Pérez, Astrid; Gómez, Manuel J.; Gayoso, Carmen; Vallejo, Juan A.; Ohneck, Emily J.; Valle, Jaione; Actis, Luis A.; Beceiro, Alejandro; Bou, Germán

2017-01-01

Many strains of Acinetobacter baumannii have been described as being able to form biofilm. Small non-coding RNAs (sRNAs) control gene expression in many regulatory circuits in bacteria. The aim of the present work was to provide a global description of the sRNAs produced both by planktonic and biofilm-associated (sessile) cells of A. baumannii ATCC 17978, and to compare the corresponding gene expression profiles to identify sRNAs molecules associated to biofilm formation and virulence. sRNA was extracted from both planktonic and sessile cells and reverse transcribed. cDNA was subjected to 454-pyrosequencing using the GS-FLX Titanium chemistry. The global analysis of the small RNA transcriptome revealed different sRNA expression patterns in planktonic and biofilm associated cells, with some of the transcripts only expressed or repressed in sessile bacteria. A total of 255 sRNAs were detected, with 185 of them differentially expressed in the different types of cells. A total of 9 sRNAs were expressed only in biofilm cells, while the expression of other 21 coding regions were repressed only in biofilm cells. Strikingly, the expression level of the sRNA 13573 was 120 times higher in biofilms than in planktonic cells, an observation that prompted us to further investigate the biological role of this non-coding transcript. Analyses of an isogenic mutant and over-expressing strains revealed that the sRNA 13573 gene is involved in biofilm formation and attachment to A549 human alveolar epithelial cells. The present work serves as a basis for future studies examining the complex regulatory network that regulate biofilm biogenesis and attachment to eukaryotic cells in A. baumannii ATCC 17978. PMID:28763494

Coupled transcription and processing of mouse ribosomal RNA in a cell-free system.

PubMed Central

Mishima, Y; Mitsuma, T; Ogata, K

1985-01-01

An in vitro processing system of mouse rRNA was achieved using an RNA polymerase I-specific transcription system, (S100) and recombinant plasmids consisting of mouse rRNA gene (rDNA) segments containing the transcription initiation and 5'-terminal region of 18S (or 41S) rRNA. Pulse-chase experiments showed that a specific processing occurred with transcripts of the plasmid DNAs when the direction of transcription was the correct orientation relative to the 18S rRNA coding sequence, but not with transcripts of the DNA templates in which this coding sequence was in the opposite orientation. From the S1 nuclease protection analyses, we concluded that there are several steps of endonucleolytic cleavage including one 105 nucleotides upstream from the 5' end of 18S rRNA. Intermediates cleaved at this site were identified in in vivo processing of rRNA. This result indicates that endonucleolytic cleavage takes place 105 nucleotides upstream from the 5' terminus of 18S rRNA prior to the formation of mature 18S rRNA. Trimming or cleavage of the 105 nucleotides may be involved in the formation of the 5' terminus of mature 18S rRNA. Images Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. PMID:3004977

Improving the genome annotation of the acarbose producer Actinoplanes sp. SE50/110 by sequencing enriched 5'-ends of primary transcripts.

PubMed

Schwientek, Patrick; Neshat, Armin; Kalinowski, Jörn; Klein, Andreas; Rückert, Christian; Schneiker-Bekel, Susanne; Wendler, Sergej; Stoye, Jens; Pühler, Alfred

2014-11-20

Actinoplanes sp. SE50/110 is the producer of the alpha-glucosidase inhibitor acarbose, which is an economically relevant and potent drug in the treatment of type-2 diabetes mellitus. In this study, we present the detection of transcription start sites on this genome by sequencing enriched 5'-ends of primary transcripts. Altogether, 1427 putative transcription start sites were initially identified. With help of the annotated genome sequence, 661 transcription start sites were found to belong to the leader region of protein-coding genes with the surprising result that roughly 20% of these genes rank among the class of leaderless transcripts. Next, conserved promoter motifs were identified for protein-coding genes with and without leader sequences. The mapped transcription start sites were finally used to improve the annotation of the Actinoplanes sp. SE50/110 genome sequence. Concerning protein-coding genes, 41 translation start sites were corrected and 9 novel protein-coding genes could be identified. In addition to this, 122 previously undetermined non-coding RNA (ncRNA) genes of Actinoplanes sp. SE50/110 were defined. Focusing on antisense transcription start sites located within coding genes or their leader sequences, it was discovered that 96 of those ncRNA genes belong to the class of antisense RNA (asRNA) genes. The remaining 26 ncRNA genes were found outside of known protein-coding genes. Four chosen examples of prominent ncRNA genes, namely the transfer messenger RNA gene ssrA, the ribonuclease P class A RNA gene rnpB, the cobalamin riboswitch RNA gene cobRS, and the selenocysteine-specific tRNA gene selC, are presented in more detail. This study demonstrates that sequencing of enriched 5'-ends of primary transcripts and the identification of transcription start sites are valuable tools for advanced genome annotation of Actinoplanes sp. SE50/110 and most probably also for other bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

Autoregulatory mechanisms controlling the microprocessor.

PubMed

Triboulet, Robinson; Gregory, Richard I

2011-01-01

The Microprocessor, comprising the ribonuclease Drosha and its essential cofactor, the double-stranded RNA-binding protein, DGCR8, is essential for the first step of the miRNA biogenesis pathway. It specifically cleaves double-stranded RNA within stem-loop structures of primary miRNA transcripts (pri-miRNAs) to generate precursor (pre-miRNA) intermediates. Pre-miRNAs are subsequently processed by Dicer to their mature ∼22 nt form. Thus, Microprocessor is essential for miRNA maturation, and pri-miRNA cleavage by this complex defines one end of the mature miRNA. Moreover, it is emerging that dysregulation of the Microprocessor is associated with various human diseases. It is therefore important to understand the mechanisms by which the expression of the subunits of the Microprocessor is regulated. Recent findings have uncovered a post-transcriptional mechanism that maintains the integrity of the Microprocessor. These studies revealed that the Microprocessor is involved in the processing of the messenger RNA (mRNA) that encodes DGCR8. This regulatory feedback loop, along with the reported role played by DGCR8 in the stabilization of Drosha protein, is part of a newly identified regulatory mechanism controlling Microprocessor activity.

Crystal Structures of the E. coli Transcription Initiation Complexes with a Complete Bubble

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zuo, Yuhong; Steitz, Thomas A.

2015-05-01

During transcription initiation, RNA polymerase binds to promoter DNA to form an initiation complex containing a DNA bubble and enters into abortive cycles of RNA synthesis before escaping the promoter to transit into the elongation phase for processive RNA synthesis. Here we present the crystal structures of E. coli transcription initiation complexes containing a complete transcription bubble and de novo synthesized RNA oligonucleotides at about 6-Å resolution. The structures show how RNA polymerase recognizes DNA promoters that contain spacers of different lengths and reveal a bridging interaction between the 5'-triphosphate of the nascent RNA and the σ factor that maymore » function to stabilize the short RNA-DNA hybrids during the early stage of transcription initiation. The conformation of the RNA oligonucleotides and the paths of the DNA strands in the complete initiation complexes provide insights into the mechanism that controls both the abortive and productive RNA synthesis.« less

Influence of 5'-flanking sequence on 4.5SI RNA gene transcription by RNA polymerase III.

PubMed

Gogolevskaya, Irina K; Stasenko, Danil V; Tatosyan, Karina A; Kramerov, Dmitri A

2018-05-01

Short nuclear 4.5SI RNA can be found in three related rodent families. Its function remains unknown. The genes of 4.5SI RNA contain an internal promoter of RNA polymerase III composed of the boxes A and B. Here, the effect of the sequence immediately upstream of the mouse 4.5SI RNA gene on its transcription was studied. The gene with deletions and substitutions in the 5'-flanking sequence was used to transfect HeLa cells and its transcriptional activity was evaluated from the cellular level of 4.5SI RNA. Single-nucleotide substitutions in the region adjacent to the transcription start site (positions -2 to -8) decreased the expression activity of the gene down to 40%-60% of the control. The substitution of the conserved pentanucleotide AGAAT (positions -14 to -18) could either decrease (43%-56%) or increase (134%) the gene expression. A TATA-like box (TACATGA) was found at positions -24 to -30 of the 4.5SI RNA gene. Its replacement with a polylinker fragment of the vector did not decrease the transcription level, while its replacement with a GC-rich sequence almost completely (down to 2%-5%) suppressed the transcription of the 4.5SI RNA gene. The effect of plasmid sequences bordering the gene on its transcription by RNA polymerase III is discussed.

Differential utilization of TATA box-binding protein (TBP) and TBP-related factor 1 (TRF1) at different classes of RNA polymerase III promoters.

PubMed

Verma, Neha; Hung, Ko-Hsuan; Kang, Jin Joo; Barakat, Nermeen H; Stumph, William E

2013-09-20

In the fruit fly Drosophila melanogaster, RNA polymerase III transcription was found to be dependent not upon the canonical TATA box-binding protein (TBP) but instead upon the TBP-related factor 1 (TRF1) (Takada, S., Lis, J. T., Zhou, S., and Tjian, R. (2000) Cell 101, 459-469). Here we confirm that transcription of fly tRNA genes requires TRF1. However, we unexpectedly find that U6 snRNA gene promoters are occupied primarily by TBP in cells and that knockdown of TBP, but not TRF1, inhibits U6 transcription in cells. Moreover, U6 transcription in vitro effectively utilizes TBP, whereas TBP cannot substitute for TRF1 to promote tRNA transcription in vitro. Thus, in fruit flies, different classes of RNA polymerase III promoters differentially utilize TBP and TRF1 for the initiation of transcription.

RNA-Seq-Based Transcript Structure Analysis with TrBorderExt.

PubMed

Wang, Yejun; Sun, Ming-An; White, Aaron P

2018-01-01

RNA-Seq has become a routine strategy for genome-wide gene expression comparisons in bacteria. Despite lower resolution in transcript border parsing compared with dRNA-Seq, TSS-EMOTE, Cappable-seq, Term-seq, and others, directional RNA-Seq still illustrates its advantages: low cost, quantification and transcript border analysis with a medium resolution (±10-20 nt). To facilitate mining of directional RNA-Seq datasets especially with respect to transcript structure analysis, we developed a tool, TrBorderExt, which can parse transcript start sites and termination sites accurately in bacteria. A detailed protocol is described in this chapter for how to use the software package step by step to identify bacterial transcript borders from raw RNA-Seq data. The package was developed with Perl and R programming languages, and is accessible freely through the website: http://www.szu-bioinf.org/TrBorderExt .

Dissecting the chromatin interactome of microRNA genes.

PubMed

Chen, Dijun; Fu, Liang-Yu; Zhang, Zhao; Li, Guoliang; Zhang, Hang; Jiang, Li; Harrison, Andrew P; Shanahan, Hugh P; Klukas, Christian; Zhang, Hong-Yu; Ruan, Yijun; Chen, Ling-Ling; Chen, Ming

2014-03-01

Our knowledge of the role of higher-order chromatin structures in transcription of microRNA genes (MIRs) is evolving rapidly. Here we investigate the effect of 3D architecture of chromatin on the transcriptional regulation of MIRs. We demonstrate that MIRs have transcriptional features that are similar to protein-coding genes. RNA polymerase II-associated ChIA-PET data reveal that many groups of MIRs and protein-coding genes are organized into functionally compartmentalized chromatin communities and undergo coordinated expression when their genomic loci are spatially colocated. We observe that MIRs display widespread communication in those transcriptionally active communities. Moreover, miRNA-target interactions are significantly enriched among communities with functional homogeneity while depleted from the same community from which they originated, suggesting MIRs coordinating function-related pathways at posttranscriptional level. Further investigation demonstrates the existence of spatial MIR-MIR chromatin interacting networks. We show that groups of spatially coordinated MIRs are frequently from the same family and involved in the same disease category. The spatial interaction network possesses both common and cell-specific subnetwork modules that result from the spatial organization of chromatin within different cell types. Together, our study unveils an entirely unexplored layer of MIR regulation throughout the human genome that links the spatial coordination of MIRs to their co-expression and function.

RNA sequencing of synaptic and cytoplasmic Upf1-bound transcripts supports contribution of nonsense-mediated decay to epileptogenesis

PubMed Central

Mooney, Claire M.; Jimenez-Mateos, Eva M.; Engel, Tobias; Mooney, Catherine; Diviney, Mairead; Venø, Morten T.; Kjems, Jørgen; Farrell, Michael A.; O’Brien, Donncha F.; Delanty, Norman; Henshall, David C.

2017-01-01

The nonsense mediated decay (NMD) pathway is a critical surveillance mechanism for identifying aberrant mRNA transcripts. It is unknown, however, whether the NMD system is affected by seizures in vivo and whether changes confer beneficial or maladaptive responses that influence long-term outcomes such the network alterations that produce spontaneous recurrent seizures. Here we explored the responses of the NMD pathway to prolonged seizures (status epilepticus) and investigated the effects of NMD inhibition on epilepsy in mice. Status epilepticus led to increased protein levels of Up-frameshift suppressor 1 homolog (Upf1) within the mouse hippocampus. Upf1 protein levels were also higher in resected hippocampus from patients with intractable temporal lobe epilepsy. Immunoprecipitation of Upf1-bound RNA from the cytoplasmic and synaptosomal compartments followed by RNA sequencing identified unique populations of NMD-associated transcripts and altered levels after status epilepticus, including known substrates such as Arc as well as novel targets including Inhba and Npas4. Finally, long-term video-EEG recordings determined that pharmacologic interference in the NMD pathway after status epilepticus reduced the later occurrence of spontaneous seizures in mice. These findings suggest compartment-specific recruitment and differential loading of transcripts by NMD pathway components may contribute to the process of epileptogenesis. PMID:28128343

Transcriptional organization and in vivo role of the Escherichia coli rsd gene, encoding the regulator of RNA polymerase sigma D.

PubMed

Jishage, M; Ishihama, A

1999-06-01

The regulator of sigma D (Rsd) was identified as an RNA polymerase sigma70-associated protein in stationary-phase Escherichia coli with the inhibitory activity of sigma70-dependent transcription in vitro (M. Jishage and A. Ishihama, Proc. Natl. Acad. Sci. USA 95:4953-4958, 1998). Primer extension analysis of rsd mRNA indicated the presence of two promoters, sigmaS-dependent P1 and sigma70-dependent P2 with the gearbox sequence. To get insight into the in vivo role of Rsd, the expression of a reporter gene fused to either the sigma70- or sigmaS-dependent promoter was analyzed in the absence of Rsd or the presence of overexpressed Rsd. In the rsd null mutant, the sigma70- and sigmaS-dependent gene expression was increased or decreased, respectively. On the other hand, the sigma70- or sigmaS-dependent transcription was reduced or enhanced, respectively, after overexpression of Rsd. The repression of the sigmaS-dependent transcription in the rsd mutant is overcome by increased production of the sigmaS subunit. Together these observations support the prediction that Rsd is involved in replacement of the RNA polymerase sigma subunit from sigma70 to sigmaS during the transition from exponential growth to the stationary phase.

Methylation of RNA polymerase II non-consensus Lysine residues marks early transcription in mammalian cells

PubMed Central

Dias, João D; Rito, Tiago; Torlai Triglia, Elena; Kukalev, Alexander; Ferrai, Carmelo; Chotalia, Mita; Brookes, Emily; Kimura, Hiroshi; Pombo, Ana

2015-01-01

Dynamic post-translational modification of RNA polymerase II (RNAPII) coordinates the co-transcriptional recruitment of enzymatic complexes that regulate chromatin states and processing of nascent RNA. Extensive phosphorylation of serine residues at the largest RNAPII subunit occurs at its structurally-disordered C-terminal domain (CTD), which is composed of multiple heptapeptide repeats with consensus sequence Y1-S2-P3-T4-S5-P6-S7. Serine-5 and Serine-7 phosphorylation mark transcription initiation, whereas Serine-2 phosphorylation coincides with productive elongation. In vertebrates, the CTD has eight non-canonical substitutions of Serine-7 into Lysine-7, which can be acetylated (K7ac). Here, we describe mono- and di-methylation of CTD Lysine-7 residues (K7me1 and K7me2). K7me1 and K7me2 are observed during the earliest transcription stages and precede or accompany Serine-5 and Serine-7 phosphorylation. In contrast, K7ac is associated with RNAPII elongation, Serine-2 phosphorylation and mRNA expression. We identify an unexpected balance between RNAPII K7 methylation and acetylation at gene promoters, which fine-tunes gene expression levels. DOI: http://dx.doi.org/10.7554/eLife.11215.001 PMID:26687004

A Sub-Element in PRE enhances nuclear export of intronless mRNAs by recruiting the TREX complex via ZC3H18

PubMed Central

Chi, Binkai; Wang, Ke; Du, Yanhua; Gui, Bin; Chang, Xingya; Wang, Lantian; Fan, Jing; Chen, She; Wu, Xudong; Li, Guohui; Cheng, Hong

2014-01-01

Viral RNA elements that facilitate mRNA export are useful tools for identifying cellular RNA export factors. Here we show that hepatitis B virus post-transcriptional element (PRE) is one such element, and using PRE several new cellular mRNA export factors were identified. We found that PRE drastically enhances the cytoplasmic accumulation of cDNA transcripts independent of any viral protein. Systematic deletion analysis revealed the existence of a 116 nt functional Sub-Element of PRE (SEP1). The RNP that forms on the SEP1 RNA was affinity purified, in which TREX components as well as several other proteins were identified. TREX components and the SEP1-associating protein ZC3H18 are required for SEP1-mediated mRNA export. Significantly, ZC3H18 directly binds to the SEP1 RNA, interacts with TREX and is required for stable association of TREX with the SEP1-containing mRNA. Requirements for SEP1-mediated mRNA export are similar to those for splicing-dependent mRNA export. Consistent with these similarities, several SEP1-interacting proteins, including ZC3H18, ARS2, Acinus and Brr2, are required for efficient nuclear export of polyA RNAs. Together, our data indicate that SEP1 enhances mRNA export by recruiting TREX via ZC3H18. The new mRNA export factors that we identified might be involved in cap- and splicing-dependent TREX recruitment to cellular mRNAs. PMID:24782531

HuR interacts with human immunodeficiency virus type 1 reverse transcriptase, and modulates reverse transcription in infected cells

PubMed Central

Lemay, Julie; Maidou-Peindara, Priscilla; Bader, Thomas; Ennifar, Eric; Rain, Jean-Christophe; Benarous, Richard; Liu, Lang Xia

2008-01-01

Reverse transcription of the genetic material of human immunodeficiency virus type 1 (HIV-1) is a critical step in the replication cycle of this virus. This process, catalyzed by reverse transcriptase (RT), is well characterized at the biochemical level. However, in infected cells, reverse transcription occurs in a multiprotein complex – the reverse transcription complex (RTC) – consisting of viral genomic RNA associated with viral proteins (including RT) and, presumably, as yet uncharacterized cellular proteins. Very little is known about the cellular proteins interacting with the RTC, and with reverse transcriptase in particular. We report here that HIV-1 reverse transcription is affected by the levels of a nucleocytoplasmic shuttling protein – the RNA-binding protein HuR. A direct protein-protein interaction between RT and HuR was observed in a yeast two-hybrid screen and confirmed in vitro by homogenous time-resolved fluorescence (HTRF). We mapped the domain interacting with HuR to the RNAse H domain of RT, and the binding domain for RT to the C-terminus of HuR, partially overlapping the third RRM RNA-binding domain of HuR. HuR silencing with specific siRNAs greatly impaired early and late steps of reverse transcription, significantly inhibiting HIV-1 infection. Moreover, by mutagenesis and immunoprecipitation studies, we could not detect the binding of HuR to the viral RNA. These results suggest that HuR may be involved in and may modulate the reverse transcription reaction of HIV-1, by an as yet unknown mechanism involving a protein-protein interaction with HIV-1 RT. PMID:18544151

An empirical strategy to detect bacterial transcript structure from directional RNA-seq transcriptome data.

PubMed

Wang, Yejun; MacKenzie, Keith D; White, Aaron P

2015-05-07

As sequencing costs are being lowered continuously, RNA-seq has gradually been adopted as the first choice for comparative transcriptome studies with bacteria. Unlike microarrays, RNA-seq can directly detect cDNA derived from mRNA transcripts at a single nucleotide resolution. Not only does this allow researchers to determine the absolute expression level of genes, but it also conveys information about transcript structure. Few automatic software tools have yet been established to investigate large-scale RNA-seq data for bacterial transcript structure analysis. In this study, 54 directional RNA-seq libraries from Salmonella serovar Typhimurium (S. Typhimurium) 14028s were examined for potential relationships between read mapping patterns and transcript structure. We developed an empirical method, combined with statistical tests, to automatically detect key transcript features, including transcriptional start sites (TSSs), transcriptional termination sites (TTSs) and operon organization. Using our method, we obtained 2,764 TSSs and 1,467 TTSs for 1331 and 844 different genes, respectively. Identification of TSSs facilitated further discrimination of 215 putative sigma 38 regulons and 863 potential sigma 70 regulons. Combining the TSSs and TTSs with intergenic distance and co-expression information, we comprehensively annotated the operon organization in S. Typhimurium 14028s. Our results show that directional RNA-seq can be used to detect transcriptional borders at an acceptable resolution of ±10-20 nucleotides. Technical limitations of the RNA-seq procedure may prevent single nucleotide resolution. The automatic transcript border detection methods, statistical models and operon organization pipeline that we have described could be widely applied to RNA-seq studies in other bacteria. Furthermore, the TSSs, TTSs, operons, promoters and unstranslated regions that we have defined for S. Typhimurium 14028s may constitute valuable resources that can be used for comparative analyses with other Salmonella serotypes.

Mitochondrial run-on transcription assay using biotin labeling.

PubMed

Kühn, Kristina

2015-01-01

RNA synthesis and different posttranscriptional processes shape the transcriptome of plant mitochondria. It is believed that mitochondrial transcription in plants is not stringently controlled, and that RNA degradation has a major impact on mitochondrial steady-state transcript levels. Nevertheless, the presence of two RNA polymerases with different gene specificities in mitochondria of dicotyledonous species indicates that transcriptional mechanisms may provide a means to control mitochondrial steady-state RNA pools and gene expression. To experimentally assess transcriptional activities in mitochondria, run-on transcription assays have been developed. These assays measure elongation rates for endogenous transcripts in freshly prepared mitochondrial extracts. The mitochondrial run-on transcription protocol described here has been optimized for the model plant Arabidopsis (Arabidopsis thaliana). It uses mitochondria prepared from soil-grown Arabidopsis plants and employs nonradioactive labeling for the subsequent detection of run-on transcripts.

Cloning of murine RNA polymerase I-specific TAF factors: conserved interactions between the subunits of the species-specific transcription initiation factor TIF-IB/SL1.

PubMed

Heix, J; Zomerdijk, J C; Ravanpay, A; Tjian, R; Grummt, I

1997-03-04

Promoter selectivity for all three classes of eukaryotic RNA polymerases is brought about by multimeric protein complexes containing TATA box binding protein (TBP) and specific TBP-associated factors (TAFs). Unlike class II- and III-specific TBP-TAF complexes, the corresponding murine and human class I-specific transcription initiation factor TIF-IB/SL1 exhibits a pronounced selectivity for its homologous promoter. As a first step toward understanding the molecular basis of species-specific promoter recognition, we cloned the cDNAs encoding the three mouse pol I-specific TBP-associated factors (TAFIs) and compared the amino acid sequences of the murine TAFIs with their human counterparts. The four subunits from either species can form stable chimeric complexes that contain stoichiometric amounts of TBP and TAFIs, demonstrating that differences in the primary structure of human and mouse TAFIs do not dramatically alter the network of protein-protein contacts responsible for assembly of the multimeric complex. Thus, primate vs. rodent promoter selectivity mediated by the TBP-TAFI complex is likely to be the result of cumulative subtle differences between individual subunits that lead to species-specific properties of RNA polymerase I transcription.

Isolation and identification of gene-specific microRNAs.

PubMed

Lin, Shi-Lung; Chang, Donald C; Ying, Shao-Yao

2013-01-01

Computer programming has identified hundreds of genomic hairpin sequences, many with functions remain to be determined. Because direct transfection of hairpin-like miRNA precursors (pre)-miRNAs in mammalian cells is not always sufficient to trigger effective RNA-induced gene silencing complex (RISC) assembly, a key step for RNA interference (RNAi)-related gene silencing, we developed an intronic miRNA-expressing system to overcome this problem by inserting a hairpin-like pre-miRNA structure into the intron region of a gene and successfully increased the efficiency and effectiveness of miRNA-associated RNAi induction in vitro and in vivo. This intronic miRNA biogenesis has been found to depend on a coupled interaction of nascent precursor messenger RNA transcription and intron excision within a specific nuclear region proximal to genomic perichromatin fibrils. The intronic miRNA was transcribed by RNA type II polymerases, coexpressed with a primary gene transcript, and excised out of its encoding gene transcript by intracellular RNA splicing and processing mechanisms. Currently, some ribonuclease III endonucleases have been found to be involved in the processing of spliced introns and probably facilitating the intronic miRNA maturation. Using this miRNA generation system, we have shown for the first time that the intron-derived miRNAs were able to induce strong RNAi effects in not only human and mouse cells but also zebrafishes, chicken embryos, and adult mice. We have also developed an miRNA isolation protocol, based on the complementarity between the designed miRNA and its target gene sequence, to purify and identify the mature miRNAs generated by the intronic miRNA-expressing system. Several intronic miRNA identities and structures are currently confirmed to be active in vitro and in vivo. According to this proven-of-principle method, we now have full knowledge to design pre-miRNA inserts that are more efficient and effective for the intronic miRNA-expressing systems.

DNA binding by the ribosomal DNA transcription factor rrn3 is essential for ribosomal DNA transcription.

PubMed

Stepanchick, Ann; Zhi, Huijun; Cavanaugh, Alice H; Rothblum, Katrina; Schneider, David A; Rothblum, Lawrence I

2013-03-29

The human homologue of yeast Rrn3 is an RNA polymerase I-associated transcription factor that is essential for ribosomal DNA (rDNA) transcription. The generally accepted model is that Rrn3 functions as a bridge between RNA polymerase I and the transcription factors bound to the committed template. In this model Rrn3 would mediate an interaction between the mammalian Rrn3-polymerase I complex and SL1, the rDNA transcription factor that binds to the core promoter element of the rDNA. In the course of studying the role of Rrn3 in recruitment, we found that Rrn3 was in fact a DNA-binding protein. Analysis of the sequence of Rrn3 identified a domain with sequence similarity to the DNA binding domain of heat shock transcription factor 2. Randomization, or deletion, of the amino acids in this region in Rrn3, amino acids 382-400, abrogated its ability to bind DNA, indicating that this domain was an important contributor to DNA binding by Rrn3. Control experiments demonstrated that these mutant Rrn3 constructs were capable of interacting with both rpa43 and SL1, two other activities demonstrated to be essential for Rrn3 function. However, neither of these Rrn3 mutants was capable of functioning in transcription in vitro. Moreover, although wild-type human Rrn3 complemented a yeast rrn3-ts mutant, the DNA-binding site mutant did not. These results demonstrate that DNA binding by Rrn3 is essential for transcription by RNA polymerase I.

DNA Binding by the Ribosomal DNA Transcription Factor Rrn3 Is Essential for Ribosomal DNA Transcription*

PubMed Central

Stepanchick, Ann; Zhi, Huijun; Cavanaugh, Alice H.; Rothblum, Katrina; Schneider, David A.; Rothblum, Lawrence I.

2013-01-01

The human homologue of yeast Rrn3 is an RNA polymerase I-associated transcription factor that is essential for ribosomal DNA (rDNA) transcription. The generally accepted model is that Rrn3 functions as a bridge between RNA polymerase I and the transcription factors bound to the committed template. In this model Rrn3 would mediate an interaction between the mammalian Rrn3-polymerase I complex and SL1, the rDNA transcription factor that binds to the core promoter element of the rDNA. In the course of studying the role of Rrn3 in recruitment, we found that Rrn3 was in fact a DNA-binding protein. Analysis of the sequence of Rrn3 identified a domain with sequence similarity to the DNA binding domain of heat shock transcription factor 2. Randomization, or deletion, of the amino acids in this region in Rrn3, amino acids 382–400, abrogated its ability to bind DNA, indicating that this domain was an important contributor to DNA binding by Rrn3. Control experiments demonstrated that these mutant Rrn3 constructs were capable of interacting with both rpa43 and SL1, two other activities demonstrated to be essential for Rrn3 function. However, neither of these Rrn3 mutants was capable of functioning in transcription in vitro. Moreover, although wild-type human Rrn3 complemented a yeast rrn3-ts mutant, the DNA-binding site mutant did not. These results demonstrate that DNA binding by Rrn3 is essential for transcription by RNA polymerase I. PMID:23393135

Exploration of Molecular Factors Impairing Superoxide Dismutase Isoforms Activity in Human Senile Cataractous Lenses

PubMed Central

Rajkumar, Sankaranarayanan; Vasavada, Abhay R.; Praveen, Mamidipudi R.; Ananthan, Rajendran; Reddy, Geereddy B.; Tripathi, Harsha; Ganatra, Darshini A.; Arora, Anshul I.; Patel, Alpesh R.

2013-01-01

Purpose. To explore different molecular factors impairing the activities of superoxide dismutase (SOD) isoforms in senile cataractous lenses. Methods. Enzyme activity of SOD isoforms, levels of their corresponding cofactors copper (Cu), manganese (Mn), zinc (Zn), and expression of mRNA transcripts and proteins were determined in the lenses of human subjects with and without cataract. DNA from lens epithelium (LE) and peripheral blood was isolated. Polymerase chain reaction–single strand conformation polymorphism (PCR-SSCP) followed by sequencing was carried out to screen somatic mutations. The impact of intronic insertion/deletion (INDEL) variations on the splicing process and on the resultant transcript was evaluated. Genotyping of IVS4+42delG polymorphism of SOD1 gene was done by PCR–restriction fragment length polymorphism (RFLP). Results. A significant decrease in Cu/Zn- and Mn-SOD activity (P < 0.001) and in Cu/Zn-SOD transcript (P < 0.001) and its protein (P < 0.05) were found in cataractous lenses. No significant change in the level of copper (P = 0.36) and an increase in the level of manganese (P = 0.01) and zinc (P = 0.02) were observed in cataractous lenses. A significant positive correlation between the level of Cu/Zn-SOD activity and the levels of Cu (P = 0.003) and Zn (P = 0.005) was found in the cataractous lenses. DNA sequencing revealed three intronic INDEL variations in exon4 of SOD1 gene. Splice-junction analysis showed the potential of IVS4+42delG in creating a new cryptic acceptor site. If it is involved in alternate splicing, it could result in generation of SOD1 mRNA transcripts lacking exon4 region. Transcript analysis revealed the presence of complete SOD1 mRNA transcripts. Genotyping revealed the presence of IVS4+42delG polymorphism in all subjects. Conclusions. The decrease in the activity of SOD1 isoform in cataractous lenses was associated with the decreased level of mRNA transcripts and their protein expression and was not associated with either modulation in the level of enzyme cofactors or with INDEL variations. PMID:23970468

Conditional Inactivation of Upstream Binding Factor Reveals Its Epigenetic Functions and the Existence of a Somatic Nucleolar Precursor Body

PubMed Central

Hamdane, Nourdine; Stefanovsky, Victor Y.; Tremblay, Michel G.; Németh, Attila; Paquet, Eric; Lessard, Frédéric; Sanij, Elaine; Hannan, Ross; Moss, Tom

2014-01-01

Upstream Binding Factor (UBF) is a unique multi-HMGB-box protein first identified as a co-factor in RNA polymerase I (RPI/PolI) transcription. However, its poor DNA sequence selectivity and its ability to generate nucleosome-like nucleoprotein complexes suggest a more generalized role in chromatin structure. We previously showed that extensive depletion of UBF reduced the number of actively transcribed ribosomal RNA (rRNA) genes, but had little effect on rRNA synthesis rates or cell proliferation, leaving open the question of its requirement for RPI transcription. Using gene deletion in mouse, we now show that UBF is essential for embryo development beyond morula. Conditional deletion in cell cultures reveals that UBF is also essential for transcription of the rRNA genes and that it defines the active chromatin conformation of both gene and enhancer sequences. Loss of UBF prevents formation of the SL1/TIF1B pre-initiation complex and recruitment of the RPI-Rrn3/TIF1A complex. It is also accompanied by recruitment of H3K9me3, canonical histone H1 and HP1α, but not by de novo DNA methylation. Further, genes retain penta-acetyl H4 and H2A.Z, suggesting that even in the absence of UBF the rRNA genes can maintain a potentially active state. In contrast to canonical histone H1, binding of H1.4 is dependent on UBF, strongly suggesting that it plays a positive role in gene activity. Unexpectedly, arrest of rRNA synthesis does not suppress transcription of the 5S, tRNA or snRNA genes, nor expression of the several hundred mRNA genes implicated in ribosome biogenesis. Thus, rRNA gene activity does not coordinate global gene expression for ribosome biogenesis. Loss of UBF also unexpectedly induced the formation in cells of a large sub-nuclear structure resembling the nucleolar precursor body (NPB) of oocytes and early embryos. These somatic NPBs contain rRNA synthesis and processing factors but do not associate with the rRNA gene loci (NORs). PMID:25121932

Discovery of Organophosphate Resistance-Related Genes Associated With Well-known Resistance Mechanisms of Plutella xylostella (L.) (Lepidoptera: Plutellidae) by RNA-Seq.

PubMed

Hsu, Ju-Chun; Lin, Yu-Yu; Chang, Chia-Che; Hua, Kuo-Hsun; Chen, Mei-Ju May; Huang, Li-Hsin; Chen, Chien-Yu

2016-04-22

Pesticide resistance poses many challenges for pest control, particularly for destructive pests such as diamondback moths (Plutella xylostella). Organophosphates have been used in the field since the 1950s, leading to selection for resistance-related gene variants and the development of resistance to new insecticides in the diamondback moth. Identifying actual and potential genes involved in resistance could offer solutions for control. This study established resistant diamondback moth strains from two different collections using mevinphos. Two sets of transcriptome sequencing (RNA-Seq) data were generated for pairs of mevinphos-resistant versus susceptible (wild-type) strains. One susceptible strain containing 14 giga base pairs was assembled into a reference-based assembly using published scaffold sequences as reference. Differential expression data between resistant and susceptible strains revealed 944 transcripts (803 with annotations) showing upregulation and 427 transcripts (150 with annotations) showing downregulation. Around 6.8% of the differential expression transcripts (65) could be categorized as associated with well-known resistance mechanisms such as penetration, detoxification, and behavior response; of these 65 transcripts, 38 showed upregulation, and 12 relating to penetration were upregulated when the transcripts of 19 cytochrome P450s, 2 zeta-class glutathione S-transferases, and 4 ATP-binding cassette transporters showed upregulation. In addition, 11 groups of transcripts related to olfactory perception appeared to be downregulated in trade-off situations. Quantitative polymerase chain reaction expression results were consistent with RNA-Seq data. Possible roles of these differentially expressed genes in resistance mechanisms are discussed in this study. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Rift valley fever virus nonstructural protein NSs promotes viral RNA replication and transcription in a minigenome system.

PubMed

Ikegami, Tetsuro; Peters, C J; Makino, Shinji

2005-05-01

Rift Valley fever virus (RVFV), which belongs to the genus Phlebovirus, family Bunyaviridae, has a tripartite negative-strand genome (S, M, and L segments) and is an important mosquito-borne pathogen for domestic animals and humans. We established an RVFV T7 RNA polymerase-driven minigenome system in which T7 RNA polymerase from an expression plasmid drove expression of RNA transcripts for viral proteins and minigenome RNA transcripts carrying a reporter gene between both termini of the M RNA segment in 293T cells. Like other viruses of the Bunyaviridae family, replication and transcription of the RVFV minigenome required expression of viral N and L proteins. Unexpectedly, the coexpression of an RVFV nonstructural protein, NSs, with N and L proteins resulted in a significant enhancement of minigenome RNA replication. Coexpression of NSs protein with N and L proteins also enhanced minigenome mRNA transcription in the cells expressing viral-sense minigenome RNA transcripts. NSs protein expression increased the RNA replication of minigenomes that originated from S and L RNA segments. Enhancement of minigenome RNA synthesis by NSs protein occurred in cells lacking alpha/beta interferon (IFN-alpha/beta) genes, indicating that the effect of NSs protein on minigenome RNA replication was unrelated to a putative NSs protein-induced inhibition of IFN-alpha/beta production. Our finding that RVFV NSs protein augmented minigenome RNA synthesis was in sharp contrast to reports that Bunyamwera virus (genus Bunyavirus) NSs protein inhibits viral minigenome RNA synthesis, suggesting that RVFV NSs protein and Bunyamwera virus NSs protein have distinctly different biological roles in viral RNA synthesis.

Genome-wide mapping of infection-induced SINE RNAs reveals a role in selective mRNA export

PubMed Central

Zhao, Yang; Alla, Ravi

2017-01-01

Abstract Short interspersed nuclear elements (SINEs) are retrotransposons evolutionarily derived from endogenous RNA Polymerase III RNAs. Though SINE elements have undergone exaptation into gene regulatory elements, how transcribed SINE RNA impacts transcriptional and post-transcriptional regulation is largely unknown. This is partly due to a lack of information regarding which of the loci have transcriptional potential. Here, we present an approach (short interspersed nuclear element sequencing, SINE-seq), which selectively profiles RNA Polymerase III-derived SINE RNA, thereby identifying transcriptionally active SINE loci. Applying SINE-seq to monitor murine B2 SINE expression during a gammaherpesvirus infection revealed transcription from 28 270 SINE loci, with ∼50% of active SINE elements residing within annotated RNA Polymerase II loci. Furthermore, B2 RNA can form intermolecular RNA–RNA interactions with complementary mRNAs, leading to nuclear retention of the targeted mRNA via a mechanism involving p54nrb. These findings illuminate a pathway for the selective regulation of mRNA export during stress via retrotransposon activation. PMID:28334904

A complex structure in the mRNA of Tf1 is recognized and cleaved to generate the primer of reverse transcription.

PubMed

Lin, J H; Levin, H L

1997-01-15

All retroviruses and LTR-containing retrotransposons are thought to require specific tRNA molecules to serve as primers of reverse transcription. An exception is the LTR-containing retrotransposon Tf1, isolated from Schizosaccharomyces pombe. Instead of requiring a tRNA, the reverse transcriptase of Tf1 uses the first 11 bases of the Tf1 transcript as the primer for reverse transcription. The primer is generated by a cleavage that occurs between bases 11 and 12 of the Tf1 mRNA. Sequence analysis of the 5' untranslated region of the Tf1 mRNA resulted in the identification of a region with the potential to form an RNA structure of 89 bases that included the primer binding site and the first 11 bases of the Tf1 mRNA. Systematic mutagenesis of this region revealed 34 single-point mutants in the structure that resulted in reduced transposition activity. The defects in transposition correlated with reduced level of Tf1 reverse transcripts as determined by DNA blot analysis. Evidence that the RNA structure did form in vivo included the result that strains with second site mutations that restored complementarity resulted in increased levels of reverse transcripts and Tf1 transposition. The majority of the mutants defective for reverse transcription were unable to cleave the Tf1 mRNA between bases 11 and 12. These data indicate that formation of an extensive RNA structure was required for the cleavage reaction that generated the primer for Tf1 reverse transcription.

[Participation of the piRNA pathway in recruiting a component of RNA polymerase I transcription initiation complex to germline cell nucleoli].

PubMed

Fefelova, E A; Stolyarenko, A D; Yakushev, E Y; Gvozdev, V A; Klenov, M S

2017-01-01

Proteins of the Piwi family and short Piwi-interacting RNAs (piRNAs) ensure the protection of the genome from transposable elements. We have previously shown that nuclear Piwi protein tends to concentrate in the nucleoli of the cells of Drosophila melanogaster ovaries. It could be hypothesized that the function of Piwi in the nucleolus is associated with the repression of R1 and R2 retrotransposons inserted into the rDNA cluster. Here, we show that Piwi participates in recruiting Udd protein to nucleoli. Udd is a component of the conserved Selectivity Factor I-like (SL1-like) complex, which is required for transcription initiation by RNA polymerase I. We found that Udd localization depends on Piwi in germline cells, but not in somatic cells of the ovaries. In contrast, knockdowns of the SL1-like components (Udd or TAF1b) do not disrupt Piwi localization. We also observed that the absence of Udd or TAF1b in germline cells, as well as the impairment of Piwi nuclear localization lead to the accumulation of late stage egg chambers in the ovaries, which could be explained by reduced rRNA transcription. These results allow us to propose for the first time a role for Piwi in the nucleolus that is not directly associated with transposable element repression.

Accurate, Streamlined Analysis of mRNA Translation by Sucrose Gradient Fractionation

PubMed Central

Aboulhouda, Soufiane; Di Santo, Rachael; Therizols, Gabriel; Weinberg, David

2017-01-01

The efficiency with which proteins are produced from mRNA molecules can vary widely across transcripts, cell types, and cellular states. Methods that accurately assay the translational efficiency of mRNAs are critical to gaining a mechanistic understanding of post-transcriptional gene regulation. One way to measure translational efficiency is to determine the number of ribosomes associated with an mRNA molecule, normalized to the length of the coding sequence. The primary method for this analysis of individual mRNAs is sucrose gradient fractionation, which physically separates mRNAs based on the number of bound ribosomes. Here, we describe a streamlined protocol for accurate analysis of mRNA association with ribosomes. Compared to previous protocols, our method incorporates internal controls and improved buffer conditions that together reduce artifacts caused by non-specific mRNA–ribosome interactions. Moreover, our direct-from-fraction qRT-PCR protocol eliminates the need for RNA purification from gradient fractions, which greatly reduces the amount of hands-on time required and facilitates parallel analysis of multiple conditions or gene targets. Additionally, no phenol waste is generated during the procedure. We initially developed the protocol to investigate the translationally repressed state of the HAC1 mRNA in S. cerevisiae, but we also detail adapted procedures for mammalian cell lines and tissues. PMID:29170751

Evidence for the packaging of multiple copies of Tf1 mRNA into particles and the trans priming of reverse transcription.

PubMed

Haag, A L; Lin, J H; Levin, H L

2000-08-01

Long terminal repeat (LTR)-containing retrotransposons and retroviruses are close relatives that possess similar mechanisms of reverse transcription. The particles of retroviruses package two copies of viral mRNA that both function as templates for the reverse transcription of the element. We studied the LTR-retrotransposon Tf1 of Schizosaccharomyces pombe to test whether multiple copies of transposon mRNA participate in the production of cDNA. Using the unique self-priming property of Tf1, we obtained evidence that multiple copies of Tf1 mRNA were packaged into virus-like particles. By coexpressing two distinct versions of Tf1, we found that the bulk of reverse transcription that was initiated on one mRNA template was subsequently transferred to others. In addition, the first 11 nucleotides of one mRNA were able to prime, in trans, the reverse transcription of another mRNA.

RNA-binding Protein Quaking Stabilizes Sirt2 mRNA during Oligodendroglial Differentiation*

PubMed Central

Thangaraj, Merlin P.; Furber, Kendra L.; Gan, Jotham K.; Ji, Shaoping; Sobchishin, Larhonda; Doucette, J. Ronald; Nazarali, Adil J.

2017-01-01

Myelination is controlled by timely expression of genes involved in the differentiation of oligodendrocyte precursor cells (OPCs) into myelinating oligodendrocytes (OLs). Sirtuin 2 (SIRT2), a NAD+-dependent deacetylase, plays a critical role in OL differentiation by promoting both arborization and downstream expression of myelin-specific genes. However, the mechanisms involved in regulating SIRT2 expression during OL development are largely unknown. The RNA-binding protein quaking (QKI) plays an important role in myelination by post-transcriptionally regulating the expression of several myelin specific genes. In quaking viable (qkv/qkv) mutant mice, SIRT2 protein is severely reduced; however, it is not known whether these genes interact to regulate OL differentiation. Here, we report for the first time that QKI directly binds to Sirt2 mRNA via a common quaking response element (QRE) located in the 3′ untranslated region (UTR) to control SIRT2 expression in OL lineage cells. This interaction is associated with increased stability and longer half-lives of Sirt2.1 and Sirt2.2 transcripts leading to increased accumulation of Sirt2 transcripts. Consistent with this, overexpression of qkI promoted the expression of Sirt2 mRNA and protein. However, overexpression of the nuclear isoform qkI-5 promoted the expression of Sirt2 mRNA, but not SIRT2 protein, and delayed OL differentiation. These results suggest that the balance in the subcellular distribution and temporal expression of QKI isoforms control the availability of Sirt2 mRNA for translation. Collectively, our study demonstrates that QKI directly plays a crucial role in the post-transcriptional regulation and expression of Sirt2 to facilitate OL differentiation. PMID:28188285

RNA Binding Proteins in Eye Development and Disease: Implication of Conserved RNA Granule Components

PubMed Central

Dash, Soma; Siddam, Archana D.; Barnum, Carrie E.; Janga, Sarath Chandra

2016-01-01

The molecular biology of metazoan eye development is an area of intense investigation. These efforts have led to the surprising recognition that although insect and vertebrate eyes have dramatically different structures, the orthologs or family members of several conserved transcription and signaling regulators such as Pax6, Six3, Prox1 and Bmp4 are commonly required for their development. In contrast, our understanding of post-transcriptional regulation in eye development and disease, particularly regarding the function of RNA binding proteins (RBPs), is limited. We examine the present knowledge of RBPs in eye development in the insect model Drosophila, as well as several vertebrate models such as fish, frog, chicken and mouse. Interestingly, of the 42 RBPs that have been investigated with for their expression or function in vertebrate eye development, 24 (~60%) are recognized in eukaryotic cells as components of RNA granules such as Processing bodies (P-bodies), Stress granules, or other specialized ribonucleoprotein (RNP) complexes. We discuss the distinct developmental and cellular events that may necessitate potential RBP/RNA granule-associated RNA regulon models to facilitate post-transcriptional control of gene expression in eye morphogenesis. In support of these hypotheses, three RBPs and RNP/RNA granule components Tdrd7, Caprin2 and Stau2 are linked to ocular developmental defects such as congenital cataract, Peters anomaly and microphthalmia in human patients or animal models. We conclude by discussing the utility of interdisciplinary approaches such as the bioinformatics tool iSyTE (integrated Systems Tool for Eye gene discovery) to prioritize RBPs for deriving post-transcriptional regulatory networks in eye development and disease. PMID:27133484

RNA polymerases IV and V influence the 3' boundaries of Polymerase II transcription units in Arabidopsis.

PubMed

McKinlay, Anastasia; Podicheti, Ram; Wendte, Jered M; Cocklin, Ross; Rusch, Douglas B

2018-02-01

Nuclear multisubunit RNA polymerases IV and V (Pol IV and Pol V) evolved in plants as specialized forms of Pol II. Their functions are best understood in the context of RNA-directed DNA methylation (RdDM), a process in which Pol IV-dependent 24 nt siRNAs direct the de novo cytosine methylation of regions transcribed by Pol V. Pol V has additional functions, independent of Pol IV and 24 nt siRNA biogenesis, in maintaining the repression of transposons and genomic repeats whose silencing depends on maintenance cytosine methylation. Here we report that Pol IV and Pol V play unexpected roles in defining the 3' boundaries of Pol II transcription units. Nuclear run-on assays reveal that in the absence of Pol IV or Pol V, Pol II occupancy downstream of poly A sites increases for approximately 12% of protein-coding genes. This effect is most pronounced for convergently transcribed gene pairs. Although Pols IV and V are detected near transcript ends of the affected Pol II - transcribed genes, their role in limiting Pol II read-through is independent of siRNA biogenesis or cytosine methylation for the majority of these genes. Interestingly, we observed that splicing was less efficient in pol IV or pol V mutant plants, compared to wild-type plants, suggesting that Pol IV or Pol V might affect pre-mRNA processing. We speculate that Pols IV and V (and/or their associated factors) play roles in Pol II transcription termination and pre-mRNA splicing by influencing polymerase elongation rates and/or release at collision sites for convergent genes.

The Role of CYP3A4 mRNA Transcript with Shortened 3′-Untranslated Region in Hepatocyte Differentiation, Liver Development, and Response to Drug InductionS⃞

PubMed Central

Li, Dan; Gaedigk, Roger; Hart, Steven N.; Leeder, J. Steven

2012-01-01

Cytochrome P450 3A4 (CYP3A4) metabolizes more than 50% of prescribed drugs. The expression of CYP3A4 changes during liver development and may be affected by the administration of some drugs. Alternative mRNA transcripts occur in more than 90% of human genes and are frequently observed in cells responding to developmental and environmental signals. Different mRNA transcripts may encode functionally distinct proteins or contribute to variability of mRNA stability or protein translation efficiency. The purpose of this study was to examine expression of alternative CYP3A4 mRNA transcripts in hepatocytes in response to developmental signals and drugs. cDNA cloning and RNA sequencing (RNA-Seq) were used to identify CYP3A4 mRNA transcripts. Three transcripts were found in HepaRG cells and liver tissues: one represented a canonical mRNA with full-length 3′-untranslated region (UTR), one had a shorter 3′-UTR, and one contained partial intron-6 retention. The alternative mRNA transcripts were validated by either rapid amplification of cDNA 3′-end or endpoint polymerase chain reaction (PCR). Quantification of the transcripts by RNA-Seq and real time quantitative PCR revealed that the CYP3A4 transcript with shorter 3′-UTR was preferentially expressed in developed livers, differentiated hepatocytes, and in rifampicin- and phenobarbital-induced hepatocytes. The CYP3A4 transcript with shorter 3′-UTR was more stable and produced more protein compared with the CYP3A4 transcript with canonical 3′-UTR. We conclude that the 3′-end processing of CYP3A4 contributes to the quantitative regulation of CYP3A4 gene expression through alternative polyadenylation, which may serve as a regulatory mechanism explaining changes of CYP3A4 expression and activity during hepatocyte differentiation and liver development and in response to drug induction. PMID:21998292

Backtracking dynamics of RNA polymerase: pausing and error correction.

PubMed

Sahoo, Mamata; Klumpp, Stefan

2013-09-18

Transcription by RNA polymerases is frequently interrupted by pauses. One mechanism of such pauses is backtracking, where the RNA polymerase translocates backward with respect to both the DNA template and the RNA transcript, without shortening the transcript. Backtracked RNA polymerases move in a diffusive fashion and can return to active transcription either by diffusive return to the position where backtracking was initiated or by cleaving the transcript. The latter process also provides a mechanism for proofreading. Here we present some exact results for a kinetic model of backtracking and analyse its impact on the speed and the accuracy of transcription. We show that proofreading through backtracking is different from the classical (Hopfield-Ninio) scheme of kinetic proofreading. Our analysis also suggests that, in addition to contributing to the accuracy of transcription, backtracking may have a second effect: it attenuates the slow down of transcription that arises as a side effect of discriminating between correct and incorrect nucleotides based on the stepping rates.

Backtracking dynamics of RNA polymerase: pausing and error correction

NASA Astrophysics Data System (ADS)

Sahoo, Mamata; Klumpp, Stefan

2013-09-01

Transcription by RNA polymerases is frequently interrupted by pauses. One mechanism of such pauses is backtracking, where the RNA polymerase translocates backward with respect to both the DNA template and the RNA transcript, without shortening the transcript. Backtracked RNA polymerases move in a diffusive fashion and can return to active transcription either by diffusive return to the position where backtracking was initiated or by cleaving the transcript. The latter process also provides a mechanism for proofreading. Here we present some exact results for a kinetic model of backtracking and analyse its impact on the speed and the accuracy of transcription. We show that proofreading through backtracking is different from the classical (Hopfield-Ninio) scheme of kinetic proofreading. Our analysis also suggests that, in addition to contributing to the accuracy of transcription, backtracking may have a second effect: it attenuates the slow down of transcription that arises as a side effect of discriminating between correct and incorrect nucleotides based on the stepping rates.

Major satellite repeat RNA stabilize heterochromatin retention of Suv39h enzymes by RNA-nucleosome association and RNA:DNA hybrid formation.

PubMed

Velazquez Camacho, Oscar; Galan, Carmen; Swist-Rosowska, Kalina; Ching, Reagan; Gamalinda, Michael; Karabiber, Fethullah; De La Rosa-Velazquez, Inti; Engist, Bettina; Koschorz, Birgit; Shukeir, Nicholas; Onishi-Seebacher, Megumi; van de Nobelen, Suzanne; Jenuwein, Thomas

2017-08-01

The Suv39h1 and Suv39h2 histone lysine methyltransferases are hallmark enzymes at mammalian heterochromatin. We show here that the mouse Suv39h2 enzyme differs from Suv39h1 by containing an N-terminal basic domain that facilitates retention at mitotic chromatin and provides an additional affinity for major satellite repeat RNA. To analyze an RNA-dependent interaction with chromatin, we purified native nucleosomes from mouse ES cells and detect that Suv39h1 and Suv39h2 exclusively associate with poly-nucleosomes. This association was attenuated upon RNaseH incubation and entirely lost upon RNaseA digestion of native chromatin. Major satellite repeat transcripts remain chromatin-associated and have a secondary structure that favors RNA:DNA hybrid formation. Together, these data reveal an RNA-mediated mechanism for the stable chromatin interaction of the Suv39h KMT and suggest a function for major satellite non-coding RNA in the organization of an RNA-nucleosome scaffold as the underlying structure of mouse heterochromatin.

[Transcription factors NF-kB, HIF-1, HIF-2, growth factor VEGF, VEGFR2 and carboanhydrase IX mRNA and protein level in the development of kidney cancer metastasis].

PubMed

Spirina, L V; Usynin, Y A; Yurmazov, Z A; Slonimskaya, E M; Kolegova, E S; Kondakova, I V

2017-01-01

Here, we have investigated the participation of nuclear factors NF-kB, HIF-1 and HIF-2, VEGF, VEGFR2, and carboanhydrase IX in clear-cell renal cancer. We have determined the expression and protein level of transcription factors, VEGF, VEGFR2, and carboanhydrase IX in tumor and normal tissues of 30 patients with kidney cancer. The Real-Time PCR and ELISA were used in the study. The low levels of HIF-1 mRNA expression associated with high levels of HIF-1 protein were also associated with metastasis. The expression levels of VEGF, VEGFR2, and their protein levels are increased in primary tumors of patients with disseminated kidney cancer compared to nonmetastatic cancer. No correlation was revealed between the content of mRNA and encoded proteins in the kidney cancer tissues. The changes in the ratios of mRNA levels and the respective proteins (HIF-1α, HIF-2, NF-kB, VEGF, VEGFR2, and carboanhydrase IX) may contribute to kidney-cancer metastasis.

Extracellular RNA profiles with human age.

PubMed

Dluzen, Douglas F; Noren Hooten, Nicole; De, Supriyo; Wood, William H; Zhang, Yongqing; Becker, Kevin G; Zonderman, Alan B; Tanaka, Toshiko; Ferrucci, Luigi; Evans, Michele K

2018-05-24

Circulating extracellular RNAs (exRNAs) are potential biomarkers of disease. We thus hypothesized that age-related changes in exRNAs can identify age-related processes. We profiled both large and small RNAs in human serum to investigate changes associated with normal aging. exRNA was sequenced in 13 young (30-32 years) and 10 old (80-85 years) African American women to identify all RNA transcripts present in serum. We identified age-related differences in several RNA biotypes, including mitochondrial transfer RNAs, mitochondrial ribosomal RNA, and unprocessed pseudogenes. Age-related differences in unique RNA transcripts were further validated in an expanded cohort. Pathway analysis revealed that EIF2 signaling, oxidative phosphorylation, and mitochondrial dysfunction were among the top pathways shared between young and old. Protein interaction networks revealed distinct clusters of functionally-related protein-coding genes in both age groups. These data provide timely and relevant insight into the exRNA repertoire in serum and its change with aging. Published 2018. This article is a U.S. Government work and is in the public domain in the USA. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

Biology in the Dry Seed: Transcriptome Changes Associated with Dry Seed Dormancy and Dormancy Loss in the Arabidopsis GA-Insensitive sleepy1-2 Mutant

PubMed Central

Nelson, Sven K.; Ariizumi, Tohru; Steber, Camille M.

2017-01-01

Plant embryos can survive years in a desiccated, quiescent state within seeds. In many species, seeds are dormant and unable to germinate at maturity. They acquire the capacity to germinate through a period of dry storage called after-ripening (AR), a biological process that occurs at 5–15% moisture when most metabolic processes cease. Because stored transcripts are among the first proteins translated upon water uptake, they likely impact germination potential. Transcriptome changes associated with the increased seed dormancy of the GA-insensitive sly1-2 mutant, and with dormancy loss through long sly1-2 after-ripening (19 months) were characterized in dry seeds. The SLY1 gene was needed for proper down-regulation of translation-associated genes in mature dry seeds, and for AR up-regulation of these genes in germinating seeds. Thus, sly1-2 seed dormancy may result partly from failure to properly regulate protein translation, and partly from observed differences in transcription factor mRNA levels. Two positive regulators of seed dormancy, DELLA GAI (GA-INSENSITIVE) and the histone deacetylase HDA6/SIL1 (MODIFIERS OF SILENCING1) were strongly AR-down-regulated. These transcriptional changes appeared to be functionally relevant since loss of GAI function and application of a histone deacetylase inhibitor led to decreased sly1-2 seed dormancy. Thus, after-ripening may increase germination potential over time by reducing dormancy-promoting stored transcript levels. Differences in transcript accumulation with after-ripening correlated to differences in transcript stability, such that stable mRNAs appeared AR-up-regulated, and unstable transcripts AR-down-regulated. Thus, relative transcript levels may change with dry after-ripening partly as a consequence of differences in mRNA turnover. PMID:29312402

Posttranscriptional regulation of retroviral gene expression: primary RNA transcripts play three roles as pre-mRNA, mRNA, and genomic RNA

PubMed Central

LeBlanc, Jason; Weil, Jason; Beemon, Karen

2013-01-01

After reverse transcription of the retroviral RNA genome and integration of the DNA provirus into the host genome, host machinery is used for viral gene expression along with viral proteins and RNA regulatory elements. Here, we discuss co-transcriptional and posttranscriptional regulation of retroviral gene expression, comparing simple and complex retroviruses. Cellular RNA polymerase II synthesizes full-length viral primary RNA transcripts that are capped and polyadenylated. All retroviruses generate a singly spliced env mRNA from this primary transcript, which encodes the viral glycoproteins. In addition, complex viral RNAs are alternatively spliced to generate accessory proteins, such as Rev, which is involved in posttranscriptional regulation of HIV-1 RNA. Importantly, the splicing of all retroviruses is incomplete; they must maintain and export a fraction of their primary RNA transcripts. This unspliced RNA functions both as the major mRNA for Gag and Pol proteins and as the packaged genomic RNA. Different retroviruses export their unspliced viral RNA from the nucleus to the cytoplasm by either Tap-dependent or Rev/CRM1-dependent routes. Translation of the unspliced mRNA involves frame-shifting or termination codon suppression so that the Gag proteins, which make up the capsid, are expressed more abundantly than the Pol proteins, which are the viral enzymes. After the viral polyproteins assemble into viral particles and bud from the cell membrane, a viral encoded protease cleaves them. Some retroviruses have evolved mechanisms to protect their unspliced RNA from decay by nonsense-mediated RNA decay and to prevent genome editing by the cellular APOBEC deaminases. PMID:23754689

The Human RNA Polymerase I Transcription Terminator Complex Acts as a Replication Fork Barrier That Coordinates the Progress of Replication with rRNA Transcription Activity.

PubMed

Akamatsu, Yufuko; Kobayashi, Takehiko

2015-05-01

In S phase, the replication and transcription of genomic DNA need to accommodate each other, otherwise their machineries collide, with chromosomal instability as a possible consequence. Here, we characterized the human replication fork barrier (RFB) that is present downstream from the 47S pre-rRNA gene (ribosomal DNA [rDNA]). We found that the most proximal transcription terminator, Sal box T1, acts as a polar RFB, while the other, Sal box T4/T5, arrests replication forks bidirectionally. The fork-arresting activity at these sites depends on polymerase I (Pol I) transcription termination factor 1 (TTF-1) and a replisome component, TIMELESS (TIM). We also found that the RFB activity was linked to rDNA copies with hypomethylated CpG and coincided with the time that actively transcribed rRNA genes are replicated. Failed fork arrest at RFB sites led to a slowdown of fork progression moving in the opposite direction to rRNA transcription. Chemical inhibition of transcription counteracted this deceleration of forks, indicating that rRNA transcription impedes replication in the absence of RFB activity. Thus, our results reveal a role of RFB for coordinating the progression of replication and transcription activity in highly transcribed rRNA genes. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Euchromatic Transposon Insertions Trigger Production of Novel Pi- and Endo-siRNAs at the Target Sites in the Drosophila Germline

PubMed Central

Olovnikov, Ivan; Abramov, Yuri; Kalmykova, Alla

2014-01-01

The control of transposable element (TE) activity in germ cells provides genome integrity over generations. A distinct small RNA–mediated pathway utilizing Piwi-interacting RNAs (piRNAs) suppresses TE expression in gonads of metazoans. In the fly, primary piRNAs derive from so-called piRNA clusters, which are enriched in damaged repeated sequences. These piRNAs launch a cycle of TE and piRNA cluster transcript cleavages resulting in the amplification of piRNA and TE silencing. Using genome-wide comparison of TE insertions and ovarian small RNA libraries from two Drosophila strains, we found that individual TEs inserted into euchromatic loci form novel dual-stranded piRNA clusters. Formation of the piRNA-generating loci by active individual TEs provides a more potent silencing response to the TE expansion. Like all piRNA clusters, individual TEs are also capable of triggering the production of endogenous small interfering (endo-si) RNAs. Small RNA production by individual TEs spreads into the flanking genomic regions including coding cellular genes. We show that formation of TE-associated small RNA clusters can down-regulate expression of nearby genes in ovaries. Integration of TEs into the 3′ untranslated region of actively transcribed genes induces piRNA production towards the 3′-end of transcripts, causing the appearance of genic piRNA clusters, a phenomenon that has been reported in different organisms. These data suggest a significant role of TE-associated small RNAs in the evolution of regulatory networks in the germline. PMID:24516406

Prdm5 Regulates Collagen Gene Transcription by Association with RNA Polymerase II in Developing Bone

PubMed Central

Galli, Giorgio Giacomo; Honnens de Lichtenberg, Kristian; Carrara, Matteo; Hans, Wolfgang; Wuelling, Manuela; Mentz, Bettina; Multhaupt, Hinke Arnolda; Fog, Cathrine Kolster; Jensen, Klaus Thorleif; Rappsilber, Juri; Vortkamp, Andrea; Coulton, Les; Fuchs, Helmut; Gailus-Durner, Valérie; Hrabě de Angelis, Martin; Calogero, Raffaele Adolfo; Couchman, John Robert; Lund, Anders Henrik

2012-01-01

PRDM family members are transcriptional regulators involved in tissue specific differentiation. PRDM5 has been reported to predominantly repress transcription, but a characterization of its molecular functions in a relevant biological context is lacking. We demonstrate here that Prdm5 is highly expressed in developing bones; and, by genome-wide mapping of Prdm5 occupancy in pre-osteoblastic cells, we uncover a novel and unique role for Prdm5 in targeting all mouse collagen genes as well as several SLRP proteoglycan genes. In particular, we show that Prdm5 controls both Collagen I transcription and fibrillogenesis by binding inside the Col1a1 gene body and maintaining RNA polymerase II occupancy. In vivo, Prdm5 loss results in delayed ossification involving a pronounced impairment in the assembly of fibrillar collagens. Collectively, our results define a novel role for Prdm5 in sustaining the transcriptional program necessary to the proper assembly of osteoblastic extracellular matrix. PMID:22589746

5-methylcytosine promotes mRNA export — NSUN2 as the methyltransferase and ALYREF as an m5C reader

PubMed Central

Yang, Xin; Yang, Ying; Sun, Bao-Fa; Chen, Yu-Sheng; Xu, Jia-Wei; Lai, Wei-Yi; Li, Ang; Wang, Xing; Bhattarai, Devi Prasad; Xiao, Wen; Sun, Hui-Ying; Zhu, Qin; Ma, Hai-Li; Adhikari, Samir; Sun, Min; Hao, Ya-Juan; Zhang, Bing; Huang, Chun-Min; Huang, Niu; Jiang, Gui-Bin; Zhao, Yong-Liang; Wang, Hai-Lin; Sun, Ying-Pu; Yang, Yun-Gui

2017-01-01

5-methylcytosine (m5C) is a post-transcriptional RNA modification identified in both stable and highly abundant tRNAs and rRNAs, and in mRNAs. However, its regulatory role in mRNA metabolism is still largely unknown. Here, we reveal that m5C modification is enriched in CG-rich regions and in regions immediately downstream of translation initiation sites and has conserved, tissue-specific and dynamic features across mammalian transcriptomes. Moreover, m5C formation in mRNAs is mainly catalyzed by the RNA methyltransferase NSUN2, and m5C is specifically recognized by the mRNA export adaptor ALYREF as shown by in vitro and in vivo studies. NSUN2 modulates ALYREF's nuclear-cytoplasmic shuttling, RNA-binding affinity and associated mRNA export. Dysregulation of ALYREF-mediated mRNA export upon NSUN2 depletion could be restored by reconstitution of wild-type but not methyltransferase-defective NSUN2. Our study provides comprehensive m5C profiles of mammalian transcriptomes and suggests an essential role for m5C modification in mRNA export and post-transcriptional regulation. PMID:28418038