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15 páginas, 11 figuras. El fichero contiene una rectificación en la página 17 ; The control of mRNA biogenesis is exerted at several steps. In response to extracellular stimuli, stress-activated protein kinases (SAPK) modulate gene expression to maximize cell survival. In yeast, the Hog1 SAPK plays a key role in reprogramming the gene expression pattern required for cell survival upon osmostress by acting during transcriptional initiation and elongation. Here, we genetically show that an intact nuclear pore complex is important for cell survival and maximal expression of stress-responsive genes. The Hog1 SAPK associates with nuclear pore complex components and directly phosphorylates the Nup1, Nup2, and Nup60 components of the inner nuclear basket. Mutation of those factors resulted in a deficient export of stress-responsive genes upon stress. Association of Nup1, Nup2, and Nup60 to stress-responsive promoters occurs upon stress depending on Hog1 activity. Accordingly, STL1 gene territory is maintained at the nuclear periphery upon osmostress in a Hog1-dependent manner. Cells containing non-phosphorylatable mutants in Nup1 or Nup2 display reduced expression of stress-responsive genes. Together, proper mRNA biogenesis of stress-responsive genes requires of the coordinate action of synthesis and export machineries by the Hog1 SAPK ; This work was supported by MINECO (Spanish government) Grant BFU2012-33503, the Consolider Ingenio 2010 program (Grant CSD2007-0015), the Fundación Marcelino Botín (to F. P.), and Grant BFU2011-26722 (to E. d. N.). Recipients of an ICREA Acadèmia (Generalitat de Catalunya). Supported by the MINECO Grant BFU2011-23418. Supported by Agence Nationale de la Recherche (Nucleopol and ODynRib-Jeune chercheur program) and Jeune équipe from Fondation pour la Recherche Médicale. ; Peer reviewed

12 páginas, 7 figuras, 1 tabla. Material suplementario en: https://doi.org/10.1016/S0092-8674(03)01025-0. The SUS1 sequences have been deposited in GenBank with the accession number AY278445. ; Gene expression is a coordinated multistep process that begins with transcription and RNA processing in the nucleus followed by mRNA export to the cytoplasm for translation. Here we report the identification of a protein, Sus1, which functions in both transcription and mRNA export. Sus1 is a nuclear protein with a concentration at the nuclear pores. Biochemical analyses show that Sus1 interacts with SAGA, a large intranuclear histone acetylase complex involved in transcription initiation, and with the Sac3-Thp1 complex, which functions in mRNA export with specific nuclear pore proteins at the nuclear basket. DNA macroarray analysis revealed that Sus1 is required for transcription regulation. Moreover, chromatin immunoprecipitation showed that Sus1 is associated with the promoter of a SAGA-dependent gene during transcription activation. Finally, mRNA export is impaired in sus1 mutants. These data provide an unexpected connection between the SAGA histone acetylase complex and the mRNA export machinery ; This work was supported by grants from the Deutsche Forschungsgemeinschaft (SFB 352, Leibniz-Programm) and Fonds der Chemischen Industrie, R.R. by a grant from NIH, and J.E.P.-O. was supported by (GEN2001-4707-C08-07) from Ministerio de Ciencia y Tecnologı́a and (QLRI-CT-1999-01333) from the European Union. S.R.-N. is a holder of a Marie Curie fellowship. ; Peer reviewed

mRNA export from the nucleus depends on the ATPase activity of the DEAD-box protein Dbp5/DDX19. Although Dbp5 has measurable ATPase activity alone, several regulatory factors (e.g., RNA, nucleoporin proteins, and the endogenous small molecule InsP6) modulate catalytic activity in vitro and in vivo to facilitate mRNA export. An analysis of the intrinsic and regulator-activated Dbp5 ATPase cycle is necessary to define how these factors control Dbp5 and mRNA export. Here, we report a kinetic and equilibrium analysis of the Saccharomyces cerevisiae Dbp5 ATPase cycle, including the influence of RNA on Dbp5 activity. These data show that ATP binds Dbp5 weakly in rapid equilibrium with a binding affinity (KT~4 mM) comparable to the KM for steady-state cycling, while ADP binds an order of magnitude more tightly (KD~0.4 mM). The overall intrinsic steady-state cycling rate constant (kcat) is limited by slow, near-irreversible ATP hydrolysis and even slower subsequent phosphate release. RNA increases kcat and rate-limiting Pi release 20-fold, although Pi release continues to limit steady-state cycling in the presence of RNA, in conjunction with RNA binding. Together, this work identifies RNA binding and Pi release as important biochemical transitions within the Dbp5 ATPase cycle and provides a framework for investigating the means by which Dbp5 and mRNA export is modulated by regulatory factors. ; E.V.W. is supported by National Science Foundation Graduate Research Fellowship No. DGE-1122492 and J.V. is supported by an Alberta Innovates Health Solutions Postdoctoral Fellowship. M.M. and Y.M. were supported by a Senior Research Fellowship from the Wellcome Trust (101908/Z/13/Z) and by National Institutes of Health grant R01 GM102869. Research support for B.M. was provided by the Natural Sciences and Engineering Research Council of Canada (RGPIN 435380), Canada Foundation for Innovation (31271), Government of Alberta Research Capacity Program, and Canada Research Chairs program. ; This is the final version of the article. It first appeared from Elsevier via https://doi.org/10.1016/j.jmb.2015.12.018

mRNA export from the nucleus depends on the ATPase activity of the DEAD-box protein Dbp5/DDX19. Although Dbp5 has measurable ATPase activity alone, several regulatory factors (e.g., RNA, nucleoporin proteins, and the endogenous small molecule InsP6) modulate catalytic activity in vitro and in vivo to facilitate mRNA export. An analysis of the intrinsic and regulator-activated Dbp5 ATPase cycle is necessary to define how these factors control Dbp5 and mRNA export. Here, we report a kinetic and equilibrium analysis of the Saccharomyces cerevisiae Dbp5 ATPase cycle, including the influence of RNA on Dbp5 activity. These data show that ATP binds Dbp5 weakly in rapid equilibrium with a binding affinity (KT~4 mM) comparable to the KM for steady-state cycling, while ADP binds an order of magnitude more tightly (KD~0.4 mM). The overall intrinsic steady-state cycling rate constant (kcat) is limited by slow, near-irreversible ATP hydrolysis and even slower subsequent phosphate release. RNA increases kcat and rate-limiting Pi release 20-fold, although Pi release continues to limit steady-state cycling in the presence of RNA, in conjunction with RNA binding. Together, this work identifies RNA binding and Pi release as important biochemical transitions within the Dbp5 ATPase cycle and provides a framework for investigating the means by which Dbp5 and mRNA export is modulated by regulatory factors. ; E.V.W. is supported by National Science Foundation Graduate Research Fellowship No. DGE-1122492 and J.V. is supported by an Alberta Innovates Health Solutions Postdoctoral Fellowship. M.M. and Y.M. were supported by a Senior Research Fellowship from the Wellcome Trust (101908/Z/13/Z) and by National Institutes of Health grant R01 GM102869. Research support for B.M. was provided by the Natural Sciences and Engineering Research Council of Canada (RGPIN 435380), Canada Foundation for Innovation (31271), Government of Alberta Research Capacity Program, and Canada Research Chairs program.

The Nuclear Pore Complex (NPC) is a fascinating structure whose functional relevance and complexity attract significant interest. Within the NPC, several different subcomplexes interact with each other to form a highly conserved and stable structure. One of these subcomplexes is the NUP107 complex, constituted by 7-9 members. A wide variety of functions have been ascribed to the NUP107 complex, ranging from NPC assembly to mRNA export to cell differentiation. Recently, genetic dissection of the NUP107 complex has provided novel insight to the assembly of the complex and has, moreover, revealed an unexpected connection with the mitotic spindle assembly checkpoint protein MAD1. ; The Spanish Ministry of Economy and Competitiveness (BFU2010-15478/BMC), the Autonomous Government of Andalusia (P08-CVI-3920) and the European Regional Development Fund are acknowledged for financial support. ; Peer Reviewed

13 páginas, 7 figuras, 2 yablas ; Anti-silencing function 1 (Asf1) is a conserved key eukaryotic histone H3/H4 chaperone that participates in a variety of DNA and chromatin-related processes. These include the assembly and disassembly of histones H3 and H4 from chromatin during replication, transcription, and DNA repair. In addition, Asf1 is required for H3K56 acetylation activity dependent on histone acetyltransferase Rtt109. Thus, Asf1 impacts on many aspects of DNA metabolism. To gain insights into the functional links of Asf1 with other cellular machineries, we employed mass spectrometry coupled to tandem affinity purification (TAP) to investigate novel physical interactions of Asf1. Under different TAP-MS analysis conditions, we describe a new repertoire of Asf1 physical interactions and novel Asf1 post-translational modifications as ubiquitination, methylation and acetylation that open up new ways to regulate Asf1 functions. Asf1 co-purifies with several subunits of the TREX-2, SAGA complexes, and with nucleoporins Nup2, Nup60, and Nup57, which are all involved in transcription coupled to mRNA export in eukaryotes. Reciprocally, Thp1 and Sus1 interact with Asf1. Albeit mRNA export and GAL1 transcription are not affected in asf1Δ a strong genetic interaction exists between ASF1 and SUS1. Notably, supporting a functional link between Asf1 and TREX-2, both Sus1 and Thp1 affect the levels of Asf1-dependent histone H3K56 acetylation and histone H3 and H4 incorporation onto chromatin. Additionally, we provide evidence for a role of Asf1 in histone H2B ubiquitination. This work proposes a functional link between Asf1 and TREX-2 components in histone metabolism at the vicinity of the nuclear pore complex. ; This work has been supported by MINECO, Spain (BFU2011-23418) and by the GV (PROMETEO/2013/061 Valencian Regional Government) grants to S.R.-N. M.P. is funded by MICINN, Spain (BFU2008-01976), and the GV (ACOMP2011/057 Valencian Regional Government). P.O.-C. and E.G.-O. are holders of a MINECO FPI grant and CIPF PhD grant respectively. ; Peer reviewed

This is an open-access article distributed under the terms of the Creative Commons Attribution License. ; THO/TREX connects transcription with genome integrity in yeast, but a role of mammalian THO in these processes is uncertain, which suggests a differential implication of mRNP biogenesis factors in genome integrity in yeast and humans. We show that human THO depletion impairs transcription elongation and mRNA export and increases instability associated with DNA breaks, leading to hyper-recombination and γH2AX and 53BP1 foci accumulation. This is accompanied by replication alteration as determined by DNA combing. Genome instability is R-loop–dependent, as deduced from the ability of the AID enzyme to increase DNA damage and of RNaseH to reduce it, or from the enhancement of R-loop–dependent class-switching caused by THOC1-depletion in CH12 murine cells. Therefore, mammalian THO prevents R-loop formation and has a role in genome dynamics and function consistent with an evolutionary conservation of the functional connection between these mRNP biogenesis factors and genome integrity that had not been anticipated. ; This work was funded by grants from the Spanish Ministry of Science and Innovation (BFU2006-05260, BFU2010-16372, and Consolider Ingenio 2010 CSD2007-015), the Junta de Andalucía (BIO102, CVI624, and CVI4567), and the European Union (FEDER). ; Peer reviewed

R loops are an important source of genome instability, largely due to their negative impact on replication progression. Yra1/ALY is an abundant RNA-binding factor conserved from yeast to humans and required for mRNA export, but its excess causes lethality and genome instability. Here, we show that, in addition to ssDNA and ssRNA, Yra1 binds RNA–DNA hybrids in vitro and, when artificially overexpressed, can be recruited to chromatin in an RNA–DNA hybrid-dependent manner, stabilizing R loops and converting them into replication obstacles in vivo. Importantly, an excess of Yra1 increases R-loop-mediated genome instability caused by transcription–replication collisions regardless of whether they are codirectional or head-on. It also induces telomere shortening in telomerase-negative cells and accelerates senescence, consistent with a defect in telomere replication. Our results indicate that RNA–DNA hybrids form transiently in cells regardless of replication and, after stabilization by excess Yra1, compromise genome integrity, in agreement with a two-step model of R-loop-mediated genome instability. This work opens new perspectives to understand transcription-associated genome instability in repair-deficient cells, including tumoral cells ; Research was funded by grants from the European Research Council (ERC2014 AdG669898 TARLOOP), the Spanish Ministry of Economy and Competitiveness (BFU2016-75058-P), the Junta de Andalucía (PA12-BIO1238), and the European Union Regional Funds (FEDER) to A.A., and the Ligue Nationale Contre le Cancer (Équipe Labellisée) to V.G. P.A. was the recipient of Région Provence- Alpes-Côte d'Azur and Association pour la Recherche Contre le Cancer (ARC) predoctoral training grants. ; Peer reviewed

The THSC/TREX-2 complex of Saccharomyces cerevisiae mediates the anchoring of transcribed genes to the nuclear pore, linking transcription elongation with mRNA export and genome stability, as shown for specific reporters. However, it is still unknown whether the function of TREX-2 is global and the reason for its relevant role in genome integrity. Here, by studying two TREX-2 representative subunits, Thp1 and Sac3, we show that TREX-2 has a genome-wide role in gene expression. Both proteins show similar distributions along the genome, with a gradient disposition at active genes that increases towards the 3 end. Thp1 and Sac3 have a relevant impact on the expression of long, G+C-rich and highly transcribed genes. Interestingly, replication impairment detected by the genome-wide accumulation of the replicative Rrm3 helicase is increased preferentially at highly expressed genes in the thp1Δ and sac3Δ mutants analyzed. Therefore, our work provides evidence of a function of TREX-2 at the genome-wide level and suggests a role for TREX-2 in preventing transcription– replication conflicts, as a source of genome instability derived from a defective messenger ribonucleoprotein particle (mRNP) biogenesis. ; Spanish Ministry of Economy and Competitiveness [BFU2010-16372]; Junta de Andalucía [CVI4567 and P12/BIO-1238]; European Union (FEDER); and a JAE predoctoral training grant from the Spanish Research Council (CSIC) [to J.M.S-P.]. Funding for open access charge: Spanish Ministry of Economy and Competitiveness [BFU2010-16372]. ; Peer reviewed

Although human nucleoporin Tpr is frequently deregulated in cancer, its roles are poorly understood. Here we show that Tpr depletion generates transcription-dependent replication stress, DNA breaks, and genomic instability. DNA fiber assays and electron microscopy visualization of replication intermediates show that Tpr deficient cells exhibit slow and asymmetric replication forks under replication stress. Tpr deficiency evokes enhanced levels of DNA-RNA hybrids. Additionally, complementary proteomic strategies identify a network of Tpr-interacting proteins mediating RNA processing, such as MATR3 and SUGP2, and functional experiments confirm that their depletion trigger cellular phenotypes shared with Tpr deficiency. Mechanistic studies reveal the interplay of Tpr with GANP, a component of the TREX-2 complex. The Tpr-GANP interaction is supported by their shared protein level alterations in a cohort of ovarian carcinomas. Our results reveal links between nucleoporins, DNA transcription and replication, and the existence of a network physically connecting replication forks with transcription, splicing, and mRNA export machinery. ; The research was funded by the grants from the Fondazione AIRC per la Ricerca sul Cancro to M.F.; grants from Danish Cancer Society, Novo Nordisk Foundation, Danish National Research Foundation (project CARD), Swedish Research Council, Grant Agency of the Czech Republic (GACR 19-21325S), and Lundbeck Foundation to J.B.; and grants from the European Research Council (ERC2014 AdG669898 TARLOOP), the Spanish Ministry of Economy and Competitiveness (BFU2016-75058-P), and European Union Regional Funds (FEDER) to A.A. Author F.G-B. was a recipient of a predoctoral training fellowship of the Spanish Ministry of Education, Culture and Sports. Work of V.C. has been supported by Associazione Italiana per la Ricerca sul Cancro, AIRC-IG Ref: 21824 and by AIRC-FIRC fellowship assigned to M.A.R.-O., Ref: 2531. M.K. has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 707600, and from the Fondazione Umberto Veronesi (Milano, Italy), Post-doctoral Fellowships 2019 and 2020.

© 2020 The Author(s). ; Upon acute heat stress (HS), overall mRNA transcription, processing, and export are inhibited, leading to cell growth arrest. However, how cells turn off mRNA metabolism is not fully understood. Here, we show that acute HS results in the segregation and aggregation of multiple nuclear and nucleolar proteins into ring-like structures located at the nucleolar periphery (nucleolar rings [NuRs]). NuRs sequester essential factors required for nuclear mRNA metabolism and nuclear pore complex function, as well as cell-cycle regulators. When cells are switched back to growing temperatures, NuRs disaggregate, and their components relocate to their functional environments in an Hsf1- and Hsp104-dependent manner, and concomitantly with the reinitiation of cell growth. These findings highlight the contribution of reversible protein aggregation to the inhibition of overall RNA-related activities in the nucleus and its functional relevance in the maintenance of cellular homeostasis during acute HS. ; This work was supported by the Ministerio de Economía y Competitividad from the Spanish Government (grants BFU2015-70604-P and PGC2018-099849-B-I00 to R.R.D.) and by the Junta de Andalucia-FEDER-UPO (grant UPO-1264663 to S.S.-P.). P.G. is funded by the Universidad Pablo de Olavide (Beca Puente Ref.: PP1-1402) and by grants BFU2015-70604-P and PGC2018-099849-B-I00.

This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License. ; Gene expression in eukaryotes is an essential process that includes transcription, RNA processing, and export. One important player in this interface is the poly(A)+-RNA–binding protein Nab2, which regulates the mRNA poly(A)+-tail length and export. Here we show that Nab2 has additional roles during mRNA transcription, tRNA metabolism, and ribosomal subunit export. Nab2 is associated with the entire open reading frame of actively transcribed RNA polymerase (RNAP) II and III genes. As a consequence, nab2 mutations confer translation defects that are detected by polysome profiling. Genome-wide analysis of expression of a conditional degron nab2 mutant shows that the role of Nab2 in RNAPII transcription and RNAPIII metabolism is direct. Taken together, our results identify novel functions for Nab2 in transcription and metabolism of most types of RNAs, indicating that Nab2 function is more ubiquitous than previously anticipated, and that it is a central player in the general and coordinated control of gene expression from transcription to translation. ; This work was supported by grants from the Spanish Ministry of Science and Innovation (BFU2006-05260 and BFU2007-28647-E to A.A. and BFU2007-60151 to J.dlC.), the Junta de Andalucía (BIO-102 and CVI-2549 to A.A. and CVI-03508 to J.dlC.), and the European Union (FEDER). C.G.-A. was the recipient of a Formación del Profesorado Universitario predoctoral training grant from the Spanish Ministry of Science and Innovation. R.B. is a recipient of a fellowship from the Junta de Andalucía. ; Peer reviewed

There are over 100 different chemical RNA modifications, collectively known as the epitranscriptome. N6-methyladenosine (m6A) is the most commonly found internal RNA modification in cellular mRNAs where it plays important roles in the regulation of the mRNA structure, stability, translation and nuclear export. This modification is also found in viral RNA genomes and in viral mRNAs derived from both RNA and DNA viruses. A growing body of evidence indicates that m6A modifications play important roles in regulating viral replication by interacting with the cellular m6A machinery. In this review, we will exhaustively detail the current knowledge on m6A modification, with an emphasis on its function in virus biology. ; This work was supported by the Spanish Ministry of Science and Innovation through grants PID2019-106959RB-I00/AEI/10.13039/501100011033, an institutional "Maria de Maeztu" Programme for Units of Excellence in R&D (CEX2018-000792-M), by the 2017 SGR 909 grant from the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement of the Generalitat de Catalunya and a Beatriu Pinós postdoctoral fellowship awarded to Belinda Baquero-Perez which is funded by the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 programme of research and innovation of the European Union under the Marie Sklodowska-Curie grant agreement No 801370. All figures in this review were drawn using BioRender.