1
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Healy E, Zhang Q, Gail EH, Agius SC, Sun G, Bullen M, Pandey V, Das PP, Polo JM, Davidovich C. The apparent loss of PRC2 chromatin occupancy as an artifact of RNA depletion. Cell Rep 2024; 43:113858. [PMID: 38416645 DOI: 10.1016/j.celrep.2024.113858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/08/2023] [Accepted: 02/08/2024] [Indexed: 03/01/2024] Open
Abstract
RNA has been implicated in the recruitment of chromatin modifiers, and previous studies have provided evidence in favor and against this idea. RNase treatment of chromatin is commonly used to study RNA-mediated regulation of chromatin modifiers, but the limitations of this approach remain unclear. RNase A treatment during chromatin immunoprecipitation (ChIP) reduces chromatin occupancy of the H3K27me3 methyltransferase Polycomb repressive complex 2 (PRC2). This led to suggestions of an "RNA bridge" between PRC2 and chromatin. Here, we show that RNase A treatment during ChIP causes the apparent loss of all facultative heterochromatin, including both PRC2 and H3K27me3 genome-wide. We track this observation to a gain of DNA from non-targeted chromatin, sequenced at the expense of DNA from facultative heterochromatin, which reduces ChIP signals. Our results emphasize substantial limitations in using RNase A treatment for mapping RNA-dependent chromatin occupancy and invalidate conclusions that were previously established for PRC2 based on this assay.
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Affiliation(s)
- Evan Healy
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - Qi Zhang
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia; South Australian immunoGENomics Cancer Institute (SAiGENCI), Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA, Australia; EMBL-Australia at SAiGENCI, Adelaide, SA, Australia
| | - Emma H Gail
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - Samuel C Agius
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - Guizhi Sun
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Wellington Road, Clayton, VIC 3800, Australia
| | - Michael Bullen
- Department of Anatomy and Developmental Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Varun Pandey
- Department of Anatomy and Developmental Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Partha Pratim Das
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Wellington Road, Clayton, VIC 3800, Australia; Department of Anatomy and Developmental Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Jose M Polo
- Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Wellington Road, Clayton, VIC 3800, Australia; Department of Anatomy and Developmental Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia; Adelaide Centre for Epigenetics and South Australian immunoGENomics Cancer Institute, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Chen Davidovich
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia; EMBL-Australia, Clayton, VIC, Australia.
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Anil AT, Choudhary K, Pandian R, Gupta P, Thakran P, Singh A, Sharma M, Mishra SK. Splicing of branchpoint-distant exons is promoted by Cactin, Tls1 and the ubiquitin-fold-activated Sde2. Nucleic Acids Res 2022; 50:10000-10014. [PMID: 36095128 PMCID: PMC9508853 DOI: 10.1093/nar/gkac769] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/22/2022] [Accepted: 08/27/2022] [Indexed: 11/13/2022] Open
Abstract
Intron diversity facilitates regulated gene expression and alternative splicing. Spliceosomes excise introns after recognizing their splicing signals: the 5'-splice site (5'ss), branchpoint (BP) and 3'-splice site (3'ss). The latter two signals are recognized by U2 small nuclear ribonucleoprotein (snRNP) and its accessory factors (U2AFs), but longer spacings between them result in weaker splicing. Here, we show that excision of introns with a BP-distant 3'ss (e.g. rap1 intron 2) requires the ubiquitin-fold-activated splicing regulator Sde2 in Schizosaccharomyces pombe. By monitoring splicing-specific ura4 reporters in a collection of S. pombe mutants, Cay1 and Tls1 were identified as additional regulators of this process. The role of Sde2, Cay1 and Tls1 was further confirmed by increasing BP-3'ss spacings in a canonical tho5 intron. We also examined BP-distant exons spliced independently of these factors and observed that RNA secondary structures possibly bridged the gap between the two signals. These proteins may guide the 3'ss towards the spliceosome's catalytic centre by folding the RNA between the BP and 3'ss. Orthologues of Sde2, Cay1 and Tls1, although missing in the intron-poor Saccharomyces cerevisiae, are present in intron-rich eukaryotes, including humans. This type of intron-specific pre-mRNA splicing appears to have evolved for regulated gene expression and alternative splicing of key heterochromatin factors.
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Affiliation(s)
- Anupa T Anil
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306 Punjab, India
| | - Karan Choudhary
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306 Punjab, India
| | - Rakesh Pandian
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306 Punjab, India
| | - Praver Gupta
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306 Punjab, India
| | - Poonam Thakran
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306 Punjab, India
| | - Arashdeep Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306 Punjab, India
| | - Monika Sharma
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306 Punjab, India
| | - Shravan Kumar Mishra
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, 140306 Punjab, India
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3
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Ishida YI, Miyao S, Saito M, Hiraishi N, Nagahama M. Interactome analysis of the Tudor domain-containing protein SPF30 which associates with the MTR4-exosome RNA-decay machinery under the regulation of AAA-ATPase NVL2. Int J Biochem Cell Biol 2021; 132:105919. [PMID: 33422691 DOI: 10.1016/j.biocel.2021.105919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/23/2020] [Accepted: 12/28/2020] [Indexed: 12/24/2022]
Abstract
The AAA-ATPase NVL2 associates with an RNA helicase MTR4 and the nuclear RNA exosome in the course of ribosome biogenesis. In our proteomic screen, we had identified a ribosome biogenesis factor WDR74 as a MTR4-interacting partner, whose dissociation is stimulated by the ATP hydrolysis of NVL2. In this study, we report the identification of splicing factor 30 (SPF30), another MTR4-interacting protein with a similar regulatory mechanism. SPF30 is a pre-mRNA splicing factor harboring a Tudor domain in its central region, which regulates various cellular events by binding to dimethylarginine-modified proteins. The interaction between SPF30 and the exosome core is mediated by MTR4 and RRP6, a catalytic component of the nuclear exosome. The N- and C-terminal regions, but not the Tudor domain, of SPF30 are involved in the association with MTR4 and the exosome. The knockdown of SPF30 caused subtle delay in the 12S pre-rRNA processing to mature 5.8S rRNA, even though no obvious effect was observed on the ribosome subunit profile in the cells. Shotgun proteomic analysis to search for SPF30-interacting proteins indicated its role in ribosome biogenesis, pre-mRNA splicing, and box C/D snoRNA biogenesis. These results suggest that SPF30 collaborates with the MTR4-exosome machinery to play a functional role in multiple RNA metabolic pathways, some of which may be regulated by the ATP hydrolysis of NVL2.
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Affiliation(s)
- Yo-Ichi Ishida
- Laboratory of Molecular and Cellular Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo 204-8588, Japan
| | - Sotaro Miyao
- Laboratory of Molecular and Cellular Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo 204-8588, Japan
| | - Mitsuaki Saito
- Laboratory of Molecular and Cellular Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo 204-8588, Japan
| | - Nobuhiro Hiraishi
- Laboratory of Molecular and Cellular Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo 204-8588, Japan
| | - Masami Nagahama
- Laboratory of Molecular and Cellular Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo 204-8588, Japan.
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Zhang D, Yang JF, Gao B, Liu TY, Hao GF, Yang GF, Fu LJ, Chen MX, Zhang J. Identification, evolution and alternative splicing profile analysis of the splicing factor 30 (SPF30) in plant species. PLANTA 2019; 249:1997-2014. [PMID: 30904945 DOI: 10.1007/s00425-019-03146-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 03/19/2019] [Indexed: 06/09/2023]
Abstract
The work offers a comprehensive evaluation on the phylogenetics and conservation of splicing patterns of the plant SPF30 splicing factor gene family. In eukaryotes, one pre-mRNA can generate multiple mRNA transcripts by alternative splicing (AS), which expands transcriptome and proteome diversity. Splicing factor 30 (SPF30), also known as survival motor neuron domain containing protein 1 (SMNDC1), is a spliceosomal protein that plays an essential role in spliceosomal assembly. Although SPF30 genes have been well characterised in human and yeast, little is known about their homologues in plants. Here, we report the genome-wide identification and phylogenetic analysis of SPF30 genes in the plant kingdom. In total, 82 SPF30 genes were found in 64 plant species from algae to land plants. Alternative transcripts were found in many SPF30 genes and splicing profile analysis revealed that the second intron in SPF30 genome is frequently associated with AS events and contributed to the birth of novel exons in a few SPF30 members. In addition, different conserved sequences were observed at these putative splice sites among moss, monocots and dicots, respectively. Our findings will facilitate further functional characterization of plant SPF30 genes as putative splicing factors.
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Affiliation(s)
- Di Zhang
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Jing-Fang Yang
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Bei Gao
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Tie-Yuan Liu
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Ge-Fei Hao
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Guang-Fu Yang
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Li-Jun Fu
- Fujian Provincial Key Laboratory of Ecology-Toxicological Effects & Control for Emerging Contaminants, Putian University, Putian, 351100, Fujian, People's Republic of China
| | - Mo-Xian Chen
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong.
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China.
| | - Jianhua Zhang
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China.
- Department of Biology, Hong Kong Baptist University and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong.
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5
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Mutazono M, Morita M, Tsukahara C, Chinen M, Nishioka S, Yumikake T, Dohke K, Sakamoto M, Ideue T, Nakayama JI, Ishii K, Tani T. The intron in centromeric noncoding RNA facilitates RNAi-mediated formation of heterochromatin. PLoS Genet 2017; 13:e1006606. [PMID: 28231281 PMCID: PMC5322907 DOI: 10.1371/journal.pgen.1006606] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 01/25/2017] [Indexed: 12/20/2022] Open
Abstract
In fission yeast, the formation of centromeric heterochromatin is induced through the RNA interference (RNAi)-mediated pathway. Some pre-mRNA splicing mutants (prp) exhibit defective formation of centromeric heterochromatin, suggesting that splicing factors play roles in the formation of heterochromatin, or alternatively that the defect is caused by impaired splicing of pre-mRNAs encoding RNAi factors. Herein, we demonstrate that the splicing factor spPrp16p is enriched at the centromere, and associates with Cid12p (a factor in the RNAi pathway) and the intron-containing dg ncRNA. Interestingly, removal of the dg intron, mutations of its splice sites, or replacement of the dg intron with an euchromatic intron significantly decreased H3K9 dimethylation. We also revealed that splicing of dg ncRNA is repressed in cells and its repression depends on the distance from the transcription start site to the intron. Inefficient splicing was also observed in other intron-containing centromeric ncRNAs, dh and antisense dg, and splicing of antisense dg ncRNA was repressed in the presence of the RNAi factors. Our results suggest that the introns retained in centromeric ncRNAs work as facilitators, co-operating with splicing factors assembled on the intron and serving as a platform for the recruitment of RNAi factors, in the formation of centromeric heterochromatin. Formation of centromeric heterochromatin is required for correct segregation of sister chromatids during mitosis. In fission yeast, formation of heterochromatin at centromeres is performed through the RNA interference (RNAi) system, which involves processing of noncoding RNAs transcribed from the centromeres. We found that the intron in the centromeric dg ncRNAs facilitates formation of centromeric heterochromatin in fission yeast. We showed that the splicing factor spPrp16p associates with the RNAi factor and intron-containing dg ncRNA. Removal of or mutations in the dg intron significantly decreased H3K9 dimethylation, suggesting that the intron and associated splicing factors serve as a platform for recruitment of RNAi factors. Inefficient splicing is a hallmark of intron-containing centromeric ncRNAs. Such repression of splicing seems to be important for facilitation of heterochromatin formation. Introns in euchromatic regions are removed by splicing to generate functional RNAs, whereas centromeric introns are retained in ncRNAs by splicing repression and play roles in gene silencing. Our findings shed light on the novel roles of introns in epigenetic regulation of gene expression and heterochromatin formation.
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Affiliation(s)
- Masatoshi Mutazono
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto, Japan
| | - Misato Morita
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto, Japan
| | - Chihiro Tsukahara
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto, Japan
| | - Madoka Chinen
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto, Japan
| | - Shiori Nishioka
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto, Japan
| | - Tatsuhiro Yumikake
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto, Japan
| | - Kohei Dohke
- Laboratory of Chromosome Function and Regulation, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Misuzu Sakamoto
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto, Japan
| | - Takashi Ideue
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto, Japan
| | - Jun-Ichi Nakayama
- Graduate School of Natural Sciences, Nagoya City University, Nagoya, Japan.,Division of Chromatin Regulation, National Institute for Basic Biology, Okazaki, Japan
| | - Kojiro Ishii
- Laboratory of Chromosome Function and Regulation, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Tokio Tani
- Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kurokami, Chuo-ku, Kumamoto, Japan
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Collaborative Control of Cell Cycle Progression by the RNA Exonuclease Dis3 and Ras Is Conserved Across Species. Genetics 2016; 203:749-62. [PMID: 27029730 DOI: 10.1534/genetics.116.187930] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 03/26/2016] [Indexed: 11/18/2022] Open
Abstract
Dis3 encodes a conserved RNase that degrades or processes all RNA species via an N-terminal PilT N terminus (PIN) domain and C-terminal RNB domain that harbor, respectively, endonuclease activity and 3'-5' exonuclease activity. In Schizosaccharomyces pombe, dis3 mutations cause chromosome missegregation and failure in mitosis, suggesting dis3 promotes cell division. In humans, apparently hypomorphic dis3 mutations are found recurrently in multiple myeloma, suggesting dis3 opposes cell division. Except for the observation that RNAi-mediated depletion of dis3 function drives larval arrest and reduces tissue growth in Drosophila, the role of dis3 has not been rigorously explored in higher eukaryotic systems. Using the Drosophila system and newly generated dis3 null alleles, we find that absence of dis3 activity inhibits cell division. We uncover a conserved CDK1 phosphorylation site that when phosphorylated inhibits Dis3's exonuclease, but not endonuclease, activity. Leveraging this information, we show that Dis3's exonuclease function is required for mitotic cell division: in its absence, cells are delayed in mitosis and exhibit aneuploidy and overcondensed chromosomes. In contrast, we find that modest reduction of dis3 function enhances cell proliferation in the presence of elevated Ras activity, apparently by accelerating cells through G2/M even though each insult by itself delays G2/M. Additionally, we find that dis3 and ras genetically interact in worms and that dis3 can enhance cell proliferation under growth stimulatory conditions in murine B cells. Thus, reduction, but not absence, of dis3 activity can enhance cell proliferation in higher organisms.
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7
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Abstract
Plant genomes encode various small RNAs that function in distinct, yet overlapping, genetic and epigenetic silencing pathways. However, the abundance and diversity of small-RNA classes varies among plant species, suggesting coevolution between environmental adaptations and gene-silencing mechanisms. Biogenesis of small RNAs in plants is well understood, but we are just beginning to uncover their intricate regulation and activity. Here, we discuss the biogenesis of plant small RNAs, such as microRNAs, secondary siRNAs and heterochromatic siRNAs, and their diverse cellular and developmental functions, including in reproductive transitions, genomic imprinting and paramutation. We also discuss the diversification of small-RNA-directed silencing pathways through the expansion of RNA-dependent RNA polymerases, DICER proteins and ARGONAUTE proteins.
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Allshire RC, Ekwall K. Epigenetic Regulation of Chromatin States in Schizosaccharomyces pombe. Cold Spring Harb Perspect Biol 2015; 7:a018770. [PMID: 26134317 DOI: 10.1101/cshperspect.a018770] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This article discusses the advances made in epigenetic research using the model organism fission yeast Schizosaccharomyces pombe. S. pombe has been used for epigenetic research since the discovery of position effect variegation (PEV). This is a phenomenon in which a transgene inserted within heterochromatin is variably expressed, but can be stably inherited in subsequent cell generations. PEV occurs at centromeres, telomeres, ribosomal DNA (rDNA) loci, and mating-type regions of S. pombe chromosomes. Heterochromatin assembly in these regions requires enzymes that modify histones and the RNA interference (RNAi) machinery. One of the key histone-modifying enzymes is the lysine methyltransferase Clr4, which methylates histone H3 on lysine 9 (H3K9), a classic hallmark of heterochromatin. The kinetochore is assembled on specialized chromatin in which histone H3 is replaced by the variant CENP-A. Studies in fission yeast have contributed to our understanding of the establishment and maintenance of CENP-A chromatin and the epigenetic activation and inactivation of centromeres.
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Affiliation(s)
- Robin C Allshire
- Wellcome Trust Centre for Cell Biology, The University of Edinburgh, Edinburgh EH9 3JR, Scotland, United Kingdom
| | - Karl Ekwall
- Department of Biosciences and Nutrition, Karolinska Institutet, Center for Biosciences, NOVUM, S-141 83, Huddinge, Sweden
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Wang J, Tadeo X, Hou H, Andrews S, Moresco JJ, Yates JR, Nagy PL, Jia S. Tls1 regulates splicing of shelterin components to control telomeric heterochromatin assembly and telomere length. Nucleic Acids Res 2014; 42:11419-32. [PMID: 25245948 PMCID: PMC4191416 DOI: 10.1093/nar/gku842] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Heterochromatin preferentially forms at repetitive DNA elements through RNAi-mediated targeting of histone-modifying enzymes. It was proposed that splicing factors interact with the RNAi machinery or regulate the splicing of repeat transcripts to directly participate in heterochromatin assembly. Here, by screening the fission yeast deletion library, we comprehensively identified factors required for telomeric heterochromatin assembly, including a novel gene tls1+. Purification of Tls1 and mass spectrometry analysis of its interacting proteins show that Tls1 associates with the spliceosome subunit Brr2. RNA sequencing analysis shows that the splicing of a subset of mRNAs are affected in tls1Δ cells, including mRNAs of shelterin components rap1+ and poz1+. Importantly, replacing rap1+ and poz1+ with their cDNAs significantly alleviated heterochromatin defects of tls1Δ cells, suggesting that the missplicing of shelterin components is the cause of such defects, and that splicing factors regulate telomeric heterochromatin through the proper splicing of heterochromatin factors. In addition to its role in telomeric heterochromatin assembly, Tls1-mediated splicing of shelterin mRNAs also regulates telomere length. Given that its human homologue C9ORF78 also associates with the spliceosome and is overexpressed in multiple cancer cell lines, our results suggest that C9ORF78 overexpression might alter the proper splicing of genes during cancer progression.
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Affiliation(s)
- Jiyong Wang
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Xavier Tadeo
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Haitong Hou
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Stuart Andrews
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - James J Moresco
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Peter L Nagy
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, NY, USA
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10
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Abstract
The ability to distinguish self from non-self nucleic acids enables eukaryotes to suppress mobile elements and maintain genome integrity. In organisms from protist to human, this function is performed by RNA silencing pathways. There have been major advances in our understanding of the RNA silencing machinery, but the mechanisms by which these pathways distinguish self from non-self remain unclear. Recent studies in the yeast C. neoformans indicate that transposon-derived transcripts encode suboptimal introns and tend to stall in spliceosomes, which promotes the biogenesis of siRNA that targets these transcripts. These findings identify gene expression signal strength as a metric by which a foreign element can be distinguished from a host gene, and reveal a new function for introns and the spliceosome in genome defense. Anticipating that these principles may apply to RNA silencing in other systems, we discuss strong hints in the literature suggesting that the spliceosome may guide small RNA biogenesis in the siRNA and piRNA pathways of plants and animals.
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Affiliation(s)
- Phillip A Dumesic
- Department of Biochemistry and Biophysics; University of California; San Francisco, CA USA
| | - Hiten D Madhani
- Department of Biochemistry and Biophysics; University of California; San Francisco, CA USA
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11
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Shin JH, Chekanova JA. Arabidopsis RRP6L1 and RRP6L2 function in FLOWERING LOCUS C silencing via regulation of antisense RNA synthesis. PLoS Genet 2014; 10:e1004612. [PMID: 25211139 PMCID: PMC4161302 DOI: 10.1371/journal.pgen.1004612] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 07/18/2014] [Indexed: 01/24/2023] Open
Abstract
The exosome complex functions in RNA metabolism and transcriptional gene silencing. Here, we report that mutations of two Arabidopsis genes encoding nuclear exosome components AtRRP6L1 and AtRRP6L2, cause de-repression of the main flowering repressor FLOWERING LOCUS C (FLC) and thus delay flowering in early-flowering Arabidopsis ecotypes. AtRRP6L mutations affect the expression of known FLC regulatory antisense (AS) RNAs AS I and II, and cause an increase in Histone3 K4 trimethylation (H3K4me3) at FLC. AtRRP6L1 and AtRRP6L2 function redundantly in regulation of FLC and also act independently of the exosome core complex. Moreover, we discovered a novel, long non-coding, non-polyadenylated antisense transcript (ASL, for Antisense Long) originating from the FLC locus in wild type plants. The AtRRP6L proteins function as the main regulators of ASL synthesis, as these mutants show little or no ASL transcript. Unlike ASI/II, ASL associates with H3K27me3 regions of FLC, suggesting that it could function in the maintenance of H3K27 trimethylation during vegetative growth. AtRRP6L mutations also affect H3K27me3 levels and nucleosome density at the FLC locus. Furthermore, AtRRP6L1 physically associates with the ASL transcript and directly interacts with the FLC locus. We propose that AtRRP6L proteins participate in the maintenance of H3K27me3 at FLC via regulating ASL. Furthermore, AtRRP6Ls might participate in multiple FLC silencing pathways by regulating diverse antisense RNAs derived from the FLC locus.
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Affiliation(s)
- Jun-Hye Shin
- School of Biological Sciences, University of Missouri - Kansas City, Kansas City, Missouri, United States of America
| | - Julia A. Chekanova
- School of Biological Sciences, University of Missouri - Kansas City, Kansas City, Missouri, United States of America
- * E-mail:
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12
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Vanoosthuyse V, Legros P, van der Sar SJA, Yvert G, Toda K, Le Bihan T, Watanabe Y, Hardwick K, Bernard P. CPF-associated phosphatase activity opposes condensin-mediated chromosome condensation. PLoS Genet 2014; 10:e1004415. [PMID: 24945319 PMCID: PMC4063703 DOI: 10.1371/journal.pgen.1004415] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 04/16/2014] [Indexed: 12/03/2022] Open
Abstract
Functional links connecting gene transcription and condensin-mediated chromosome condensation have been established in species ranging from prokaryotes to vertebrates. However, the exact nature of these links remains misunderstood. Here we show in fission yeast that the 3′ end RNA processing factor Swd2.2, a component of the Cleavage and Polyadenylation Factor (CPF), is a negative regulator of condensin-mediated chromosome condensation. Lack of Swd2.2 does not affect the assembly of the CPF but reduces its association with chromatin. This causes only limited, context-dependent effects on gene expression and transcription termination. However, CPF-associated Swd2.2 is required for the association of Protein Phosphatase 1 PP1Dis2 with chromatin, through an interaction with Ppn1, a protein that we identify as the fission yeast homologue of vertebrate PNUTS. We demonstrate that Swd2.2, Ppn1 and PP1Dis2 form an independent module within the CPF, which provides an essential function in the absence of the CPF-associated Ssu72 phosphatase. We show that Ppn1 and Ssu72, like Swd2.2, are also negative regulators of condensin-mediated chromosome condensation. We conclude that Swd2.2 opposes condensin-mediated chromosome condensation by facilitating the function of the two CPF-associated phosphatases PP1 and Ssu72. Failure to properly condense chromosomes prior to their segregation in mitosis can lead to genome instability. The evolutionary-conserved condensin complex is key to the condensation process but the molecular mechanisms underlying its localization pattern on chromosomes remain unclear. Previous observations showed that the localization of condensin is intimately linked to regions of high transcription, although, somewhat paradoxically, its association with chromatin is disrupted by a processive polymerase activity. Here we identify several RNA processing factors as negative regulators of condensin in fission yeast. Two of these factors associate with PP1 phosphatase as an independent entity within the Cleavage and Polyadenylation Factor (CPF), a complex key for 3′ end RNA processing. Lack of this module induces only minor and context-dependent effects on gene expression. Our data suggest that this module helps maintaining the proper level of phosphatase activity within the CPF and thereby opposes the function of condensin in mitotic chromosome condensation.
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Affiliation(s)
- Vincent Vanoosthuyse
- CNRS, UMR5239, LBMC; Ecole Normale Supérieure de Lyon; Université Lyon 01, Lyon, France
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
| | - Pénélope Legros
- CNRS, UMR5239, LBMC; Ecole Normale Supérieure de Lyon; Université Lyon 01, Lyon, France
| | | | - Gaël Yvert
- CNRS, UMR5239, LBMC; Ecole Normale Supérieure de Lyon; Université Lyon 01, Lyon, France
| | - Kenji Toda
- Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Thierry Le Bihan
- SynthSys Edinburgh, The University of Edinburgh, Edinburgh, United Kingdom
| | - Yoshinori Watanabe
- Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Kevin Hardwick
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Pascal Bernard
- CNRS, UMR5239, LBMC; Ecole Normale Supérieure de Lyon; Université Lyon 01, Lyon, France
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13
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Kallgren SP, Andrews S, Tadeo X, Hou H, Moresco JJ, Tu PG, Yates JR, Nagy PL, Jia S. The proper splicing of RNAi factors is critical for pericentric heterochromatin assembly in fission yeast. PLoS Genet 2014; 10:e1004334. [PMID: 24874881 PMCID: PMC4038458 DOI: 10.1371/journal.pgen.1004334] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 03/06/2014] [Indexed: 11/19/2022] Open
Abstract
Heterochromatin preferentially assembles at repetitive DNA elements, playing roles in transcriptional silencing, recombination suppression, and chromosome segregation. The RNAi machinery is required for heterochromatin assembly in a diverse range of organisms. In fission yeast, RNA splicing factors are also required for pericentric heterochromatin assembly, and a prevailing model is that splicing factors provide a platform for siRNA generation independently of their splicing activity. Here, by screening the fission yeast deletion library, we discovered four novel splicing factors that are required for pericentric heterochromatin assembly. Sequencing total cellular RNAs from the strongest of these mutants, cwf14Δ, showed intron retention in mRNAs of several RNAi factors. Moreover, introducing cDNA versions of RNAi factors significantly restored pericentric heterochromatin in splicing mutants. We also found that mutations of splicing factors resulted in defective telomeric heterochromatin assembly and mis-splicing the mRNA of shelterin component Tpz1, and that replacement of tpz1+ with its cDNA partially rescued heterochromatin defects at telomeres in splicing mutants. Thus, proper splicing of RNAi and shelterin factors contributes to heterochromatin assembly at pericentric regions and telomeres.
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Affiliation(s)
- Scott P. Kallgren
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - Stuart Andrews
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
| | - Xavier Tadeo
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - Haitong Hou
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - James J. Moresco
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Patricia G. Tu
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - John R. Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Peter L. Nagy
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
- * E-mail:
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14
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Abstract
Mitotic chromosome condensation is a prerequisite for the accurate segregation of chromosomes during cell division, and the conserved condensin complex a central player of this process. However, how condensin binds chromatin and shapes mitotic chromosomes remain poorly understood. Recent genome-wide binding studies showing that in most species condensin is enriched near highly expressed genes suggest a conserved link between condensin occupancy and high transcription rates. To gain insight into the mechanisms of condensin binding and mitotic chromosome condensation, we searched for factors that collaborate with condensin through a synthetic lethal genetic screen in the fission yeast Schizosaccharomyces pombe. We isolated novel mutations affecting condensin, as well as mutations in four genes not previously implicated in mitotic chromosome condensation in fission yeast. These mutations cause chromosome segregation defects similar to those provoked by defects in condensation. We also identified a suppressor of the cut3-477 condensin mutation, which largely rescued chromosome segregation during anaphase. Remarkably, of the five genes identified in this study, four encode transcription co-factors. Our results therefore provide strong additional evidence for a functional connection between chromosome condensation and transcription.
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15
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Coy S, Volanakis A, Shah S, Vasiljeva L. The Sm complex is required for the processing of non-coding RNAs by the exosome. PLoS One 2013; 8:e65606. [PMID: 23755256 PMCID: PMC3675052 DOI: 10.1371/journal.pone.0065606] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 04/27/2013] [Indexed: 12/25/2022] Open
Abstract
A key question in the field of RNA regulation is how some exosome substrates, such as spliceosomal snRNAs and telomerase RNA, evade degradation and are processed into stable, functional RNA molecules. Typical feature of these non-coding RNAs is presence of the Sm complex at the 3′end of the mature RNA molecule. Here, we report that in Saccharomyces cerevisiae presence of intact Sm binding site is required for the exosome-mediated processing of telomerase RNA from a polyadenylated precursor into its mature form and is essential for its function in elongating telomeres. Additionally, we demonstrate that the same pathway is involved in the maturation of snRNAs. Furthermore, the insertion of an Sm binding site into an unstable RNA that is normally completely destroyed by the exosome, leads to its partial stabilization. We also show that telomerase RNA accumulates in Schizosaccharomyces pombe exosome mutants, suggesting a conserved role for the exosome in processing and degradation of telomerase RNA. In summary, our data provide important mechanistic insight into the regulation of exosome dependent RNA processing as well as telomerase RNA biogenesis.
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Affiliation(s)
- Sarah Coy
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Adam Volanakis
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Sneha Shah
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Lidia Vasiljeva
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail:
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16
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Shin JH, Wang HLV, Lee J, Dinwiddie BL, Belostotsky DA, Chekanova JA. The role of the Arabidopsis Exosome in siRNA-independent silencing of heterochromatic loci. PLoS Genet 2013; 9:e1003411. [PMID: 23555312 PMCID: PMC3610620 DOI: 10.1371/journal.pgen.1003411] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 02/11/2013] [Indexed: 01/08/2023] Open
Abstract
The exosome functions throughout eukaryotic RNA metabolism and has a prominent role in gene silencing in yeast. In Arabidopsis, exosome regulates expression of a "hidden" transcriptome layer from centromeric, pericentromeric, and other heterochromatic loci that are also controlled by small (sm)RNA-based de novo DNA methylation (RdDM). However, the relationship between exosome and smRNAs in gene silencing in Arabidopsis remains unexplored. To investigate whether exosome interacts with RdDM, we profiled Arabidopsis smRNAs by deep sequencing in exosome and RdDM mutants and also analyzed RdDM-controlled loci. We found that exosome loss had a very minor effect on global smRNA populations, suggesting that, in contrast to fission yeast, in Arabidopsis the exosome does not control the spurious entry of RNAs into smRNA pathways. Exosome defects resulted in decreased histone H3K9 dimethylation at RdDM-controlled loci, without affecting smRNAs or DNA methylation. Exosome also exhibits a strong genetic interaction with RNA Pol V, but not Pol IV, and physically associates with transcripts produced from the scaffold RNAs generating region. We also show that two Arabidopsis rrp6 homologues act in gene silencing. Our data suggest that Arabidopsis exosome may act in parallel with RdDM in gene silencing, by epigenetic effects on chromatin structure, not through siRNAs or DNA methylation.
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Affiliation(s)
- Jun-Hye Shin
- School of Biological Sciences, University of Missouri–Kansas City, Kansas City, Missouri, United States of America
| | - Hsiao-Lin V. Wang
- School of Biological Sciences, University of Missouri–Kansas City, Kansas City, Missouri, United States of America
| | - Jinwon Lee
- School of Biological Sciences, University of Missouri–Kansas City, Kansas City, Missouri, United States of America
| | - Brandon L. Dinwiddie
- School of Biological Sciences, University of Missouri–Kansas City, Kansas City, Missouri, United States of America
| | - Dmitry A. Belostotsky
- School of Biological Sciences, University of Missouri–Kansas City, Kansas City, Missouri, United States of America
| | - Julia A. Chekanova
- School of Biological Sciences, University of Missouri–Kansas City, Kansas City, Missouri, United States of America
- * E-mail:
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17
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The splicing machinery promotes RNA-directed DNA methylation and transcriptional silencing in Arabidopsis. EMBO J 2013; 32:1128-40. [PMID: 23524848 DOI: 10.1038/emboj.2013.49] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 02/07/2013] [Indexed: 12/15/2022] Open
Abstract
DNA methylation in transposons and other DNA repeats is conserved in plants as well as in animals. In Arabidopsis thaliana, an RNA-directed DNA methylation (RdDM) pathway directs de novo DNA methylation. We performed a forward genetic screen for suppressors of the DNA demethylase mutant ros1 and identified a novel Zinc-finger and OCRE domain-containing Protein 1 (ZOP1) that promotes Pol IV-dependent siRNA accumulation, DNA methylation, and transcriptional silencing. Whole-genome methods disclosed the genome-wide effects of zop1 on Pol IV-dependent siRNA accumulation and DNA methylation, suggesting that ZOP1 has both RdDM-dependent and -independent roles in transcriptional silencing. We demonstrated that ZOP1 is a pre-mRNA splicing factor that associates with several typical components of the splicing machinery as well as with Pol II. Immunofluorescence assay revealed that ZOP1 overlaps with Cajal body and is partially colocalized with NRPE1 and DRM2. Moreover, we found that the other development-defective splicing mutants tested including mac3a3b, mos4, mos12 and mos14 show defects in RdDM and transcriptional silencing. We propose that the splicing machinery rather than specific splicing factors is involved in promoting RdDM and transcriptional silencing.
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18
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Reyes-Turcu FE, Grewal SI. Different means, same end-heterochromatin formation by RNAi and RNAi-independent RNA processing factors in fission yeast. Curr Opin Genet Dev 2012; 22:156-63. [PMID: 22243696 PMCID: PMC3331891 DOI: 10.1016/j.gde.2011.12.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 12/19/2011] [Indexed: 11/28/2022]
Abstract
The assembly of heterochromatin in eukaryotic genomes is critical for diverse chromosomal events including regulation of gene expression, silencing of repetitive DNA elements, proper segregation of chromosomes and maintenance of genomic integrity. Previous studies have shown that noncoding RNAs and the RNA interference (RNAi) machinery promote the assembly of heterochromatin that serves as a multipurpose platform for targeting effectors involved in various chromosomal processes. Recent work has revealed that RNAi-independent mechanisms, involving RNA processing activities that utilize both noncoding and coding RNAs, operate in the assembly of heterochromatin. These findings have established that, in addition to coding for proteins, mRNAs also function as signaling molecules that modify chromatin structure by targeting heterochromatin assembly factors.
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Affiliation(s)
- Francisca E Reyes-Turcu
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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19
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Mankertz A. Molecular interactions of porcine circoviruses type 1 and type 2 with its host. Virus Res 2012; 164:54-60. [DOI: 10.1016/j.virusres.2011.11.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 11/01/2011] [Accepted: 11/02/2011] [Indexed: 01/19/2023]
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20
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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21
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Coy S, Vasiljeva L. The exosome and heterochromatin : multilevel regulation of gene silencing. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 702:105-21. [PMID: 21713681 DOI: 10.1007/978-1-4419-7841-7_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Heterochromatic silencing is important for repressing gene expression, protecting cells against viral invasion, maintaining DNA integrity and for proper chromosome segregation. Recently, it has become apparent that expression of eukaryotic genomesis far more complex than had previously been anticipated. Strikingly, it has emerged that most of the genome is transcribed including intergenic regions and heterochromatin, calling for us to re-address the question of how gene silencing is regulated and re-evaluate the concept ofheterochromatic regions of the genome being transcriptionally inactive. Although heterochromatic silencing can be regulated at the transcriptional level, RNA degrading activities supplied either by the exosome complex or RNAi also significantly contribute to this process. The exosome also regulates noncoding RNAs (ncRNAs) involved in the establishment of heterochromatin, further underscoring its role as the major cellular machinery involved in RNA processing and turn-over. This multilevel control of the transcriptome may be utilized to ensure greater accuracy of gene expression and allow distinction between functional transcripts and background noise. In this chapter, we will discuss the regulation of gene silencing across species, with special emphasis on the exosome's contribution to the process. We will also discuss the links between transcriptional and posttranscriptional mechanisms for gene silencing and their impact on the regulation of eukaryotic transcriptomes.
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Affiliation(s)
- Sarah Coy
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, UK
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