1
|
Du Y, Sun M, Li Z, Wu X, Qu Q, Ai H, Liu L. Mechanistic insights into the stimulation of the histone H3K9 methyltransferase Clr4 by proximal H3K14 ubiquitination. SCIENCE ADVANCES 2025; 11:eadu1864. [PMID: 40446033 PMCID: PMC12124358 DOI: 10.1126/sciadv.adu1864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2024] [Accepted: 04/24/2025] [Indexed: 06/02/2025]
Abstract
H3K9 methylation, a conserved heterochromatin marker, is crucial for chromosome segregation and gene regulation. Clr4 is the sole known methyltransferase catalyzing H3K9 methylation in Schizosaccharomyces pombe. Clr4 K455/K472 automethylation and H3K14 ubiquitination (H3K14Ub) are vital activators of Clr4, ensuring appropriate heterochromatin deposition and preventing deleterious silencing. While automethylation's activation mechanism is uncovered, the mechanism of H3K14Ub's significantly stronger stimulation on Clr4 remains unclear. Here, we determined the crystal structures of Clr4 bound to ubiquitinated and unmodified H3 peptides at 2.60 and 2.39 angstrom, which revealed a synergistic mechanism underlying the pronounced stimulatory effect: H3K14Ub increases substrate affinity through multivalent interactions and facilitates the allosteric transition of Clr4 from an inactive apo conformation to a hyperactive "catalyzing state," including conformational changes in the αC-SET-insertion region, autoregulatory loop, and the β9/10 loop. We finally propose a multilevel structural model for the Clr4 catalytic-regulatory cycle. This work provides structural insights into the interplay between histone modifications and their collective impact on epigenetic regulation.
Collapse
Affiliation(s)
- Yunxiang Du
- New Cornerstone Science Laboratory, Tsinghua-Peking Joint Center for Life Sciences, MOE Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Center for Synthetic and Systems Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Maoshen Sun
- Department of Cell Biology, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Zhengqing Li
- New Cornerstone Science Laboratory, Tsinghua-Peking Joint Center for Life Sciences, MOE Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Center for Synthetic and Systems Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Xiangwei Wu
- New Cornerstone Science Laboratory, Tsinghua-Peking Joint Center for Life Sciences, MOE Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Center for Synthetic and Systems Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Qian Qu
- Institute of Translational Medicine, National Center for Translational Medicine (Shanghai), Shanghai Jiao Tong University, Shanghai 200240, China
| | - Huasong Ai
- School of Pharmaceutical Sciences, Shanghai Frontiers Science Center of Drug Target Identification and Delivery, Shanghai Key Laboratory for Antibody-Drug Conjugates with Innovative Target, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Lei Liu
- New Cornerstone Science Laboratory, Tsinghua-Peking Joint Center for Life Sciences, MOE Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Center for Synthetic and Systems Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| |
Collapse
|
2
|
Srivastav MK, Folco HD, Nathanailidou P, Anil AT, Vijayakumari D, Jain S, Dhakshnamoorthy J, O'Neill M, Andresson T, Wheeler D, Grewal SIS. PhpC NF-Y transcription factor infiltrates heterochromatin to generate cryptic intron-containing transcripts crucial for small RNA production. Nat Commun 2025; 16:268. [PMID: 39747188 PMCID: PMC11696164 DOI: 10.1038/s41467-024-55736-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Accepted: 12/19/2024] [Indexed: 01/04/2025] Open
Abstract
The assembly of repressive heterochromatin in eukaryotic genomes is crucial for silencing lineage-inappropriate genes and repetitive DNA elements. Paradoxically, transcription of repetitive elements within constitutive heterochromatin domains is required for RNA-based mechanisms, such as the RNAi pathway, to target heterochromatin assembly proteins. However, the mechanism by which heterochromatic repeats are transcribed has been unclear. Using fission yeast, we show that the conserved trimeric transcription factor (TF) PhpCNF-Y complex can infiltrate constitutive heterochromatin via its histone-fold domains to transcribe repeat elements. PhpCNF-Y collaborates with a Zn-finger containing TF to bind repeat promoter regions with CCAAT boxes. Mutating either the TFs or the CCAAT binding site disrupts the transcription of heterochromatic repeats. Although repeat elements are transcribed from both strands, PhpCNF-Y-dependent transcripts originate from only one strand. These TF-driven transcripts contain multiple cryptic introns which are required for the generation of small interfering RNAs (siRNAs) via a mechanism involving the spliceosome and RNAi machinery. Our analyses show that siRNA production by this TF-mediated transcription pathway is critical for heterochromatin nucleation at target repeat loci. This study reveals a mechanism by which heterochromatic repeats are transcribed, initiating their own silencing by triggering a primary cascade that produces siRNAs necessary for heterochromatin nucleation.
Collapse
Affiliation(s)
- Manjit Kumar Srivastav
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - H Diego Folco
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Patroula Nathanailidou
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Anupa T Anil
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Drisya Vijayakumari
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Shweta Jain
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jothy Dhakshnamoorthy
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Maura O'Neill
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Thorkell Andresson
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - David Wheeler
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Shiv I S Grewal
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
| |
Collapse
|
3
|
Muhammad A, Sarkadi Z, Mazumder A, Ait Saada A, van Emden T, Capella M, Fekete G, Suma Sreechakram VN, Al-Sady B, Lambert SAE, Papp B, Barrales RR, Braun S. A systematic quantitative approach comprehensively defines domain-specific functional pathways linked to Schizosaccharomyces pombe heterochromatin regulation. Nucleic Acids Res 2024; 52:13665-13689. [PMID: 39565189 DOI: 10.1093/nar/gkae1024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 09/23/2024] [Accepted: 10/20/2024] [Indexed: 11/21/2024] Open
Abstract
Heterochromatin plays a critical role in regulating gene expression and maintaining genome integrity. While structural and enzymatic components have been linked to heterochromatin establishment, a comprehensive view of the underlying pathways at diverse heterochromatin domains remains elusive. Here, we developed a systematic approach to identify factors involved in heterochromatin silencing at pericentromeres, subtelomeres and the silent mating type locus in Schizosaccharomyces pombe. Using quantitative measures, iterative genetic screening and domain-specific heterochromatin reporters, we identified 369 mutants with different degrees of reduced or enhanced silencing. As expected, mutations in the core heterochromatin machinery globally decreased silencing. However, most other mutants exhibited distinct qualitative and quantitative profiles that indicate heterochromatin domain-specific functions, as seen for example for metabolic pathways affecting primarily subtelomere silencing. Moreover, similar phenotypic profiles revealed shared functions for subunits within complexes. We further discovered that the uncharacterized protein Dhm2 plays a crucial role in heterochromatin maintenance, affecting the inheritance of H3K9 methylation and the clonal propagation of the repressed state. Additionally, Dhm2 loss resulted in delayed S-phase progression and replication stress. Collectively, our systematic approach unveiled a landscape of domain-specific heterochromatin regulators controlling distinct states and identified Dhm2 as a previously unknown factor linked to heterochromatin inheritance and replication fidelity.
Collapse
Affiliation(s)
- Abubakar Muhammad
- Institute for Genetics, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Planegg-Martinsried, Germany
| | - Zsuzsa Sarkadi
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
- Synthetic and Systems Biology Unit, Institute of Biochemistry, HUN-REN Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary
- HCEMM-BRC Metabolic Systems Biology Lab, Budapesti út 9, 6728 Szeged, Hungary
| | - Agnisrota Mazumder
- Institute for Genetics, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
| | - Anissia Ait Saada
- Institut Curie, Université PSL, Université Paris-Saclay CNRS UMR3348, 91400 Orsay, France
| | - Thomas van Emden
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Planegg-Martinsried, Germany
| | - Matias Capella
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
| | - Gergely Fekete
- Synthetic and Systems Biology Unit, Institute of Biochemistry, HUN-REN Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary
- HCEMM-BRC Metabolic Systems Biology Lab, Budapesti út 9, 6728 Szeged, Hungary
| | - Vishnu N Suma Sreechakram
- Institute for Genetics, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
| | - Bassem Al-Sady
- Department of Microbiology and Immunology, George Williams Hooper Foundation, University of California San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0552, USA
| | - Sarah A E Lambert
- Institut Curie, Université PSL, Université Paris-Saclay CNRS UMR3348, 91400 Orsay, France
| | - Balázs Papp
- Synthetic and Systems Biology Unit, Institute of Biochemistry, HUN-REN Biological Research Centre, Temesvári krt. 62, 6726 Szeged, Hungary
- HCEMM-BRC Metabolic Systems Biology Lab, Budapesti út 9, 6728 Szeged, Hungary
| | - Ramón Ramos Barrales
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
| | - Sigurd Braun
- Institute for Genetics, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Grosshaderner Str. 9, 82152 Planegg-Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Planegg-Martinsried, Germany
| |
Collapse
|
4
|
Kim HS, Roche B, Bhattacharjee S, Todeschini L, Chang AY, Hammell C, Verdel A, Martienssen RA. Clr4 SUV39H1 ubiquitination and non-coding RNA mediate transcriptional silencing of heterochromatin via Swi6 phase separation. Nat Commun 2024; 15:9384. [PMID: 39477922 PMCID: PMC11526040 DOI: 10.1038/s41467-024-53417-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 10/02/2024] [Indexed: 11/02/2024] Open
Abstract
Transcriptional silencing by RNAi paradoxically relies on transcription, but how the transition from transcription to silencing is achieved has remained unclear. The Cryptic Loci Regulator complex (CLRC) in Schizosaccharomyces pombe is a cullin-ring E3 ligase required for silencing that is recruited by RNAi. We found that the E2 ubiquitin conjugating enzyme Ubc4 interacts with CLRC and mono-ubiquitinates the histone H3K9 methyltransferase Clr4SUV39H1, promoting the transition from co-transcriptional gene silencing (H3K9me2) to transcriptional gene silencing (H3K9me3). Ubiquitination of Clr4 occurs in an intrinsically disordered region (Clr4IDR), which undergoes liquid droplet formation in vitro, along with Swi6HP1 the effector of transcriptional gene silencing. Our data suggests that phase separation is exquisitely sensitive to non-coding RNA (ncRNA) which promotes self-association of Clr4, chromatin association, and di-, but not tri- methylation instead. Ubc4-CLRC also targets the transcriptional co-activator Bdf2BRD4, down-regulating centromeric transcription and small RNA (sRNA) production. The deubiquitinase Ubp3 counteracts both activities.
Collapse
Affiliation(s)
- Hyun-Soo Kim
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 11724, USA
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY, 11724, USA
| | - Benjamin Roche
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 11724, USA
- University of North Dakota, School of Medicine & Health Sciences, 1301 N Columbia Rd. Stop 9037, Grand Forks, ND, 58202, USA
| | | | - Leila Todeschini
- Institute for Advanced Biosciences, UMR InsermU1209/CNRS5309/UGA, University of Grenoble Alpes, Grenoble, France
| | - An-Yun Chang
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 11724, USA
| | | | - André Verdel
- Institute for Advanced Biosciences, UMR InsermU1209/CNRS5309/UGA, University of Grenoble Alpes, Grenoble, France
| | - Robert A Martienssen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 11724, USA.
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY, 11724, USA.
| |
Collapse
|
5
|
Gao J, Li F. Heterochromatin repeat organization at an individual level: Rex1BD and the 14-3-3 protein coordinate to shape the epigenetic landscape within heterochromatin repeats. Bioessays 2024; 46:e2400030. [PMID: 38679759 DOI: 10.1002/bies.202400030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/09/2024] [Accepted: 04/15/2024] [Indexed: 05/01/2024]
Abstract
In eukaryotic cells, heterochromatin is typically composed of tandem DNA repeats and plays crucial roles in gene expression and genome stability. It has been reported that silencing at individual units within tandem heterochromatin repeats exhibits a position-dependent variation. However, how the heterochromatin is organized at an individual repeat level remains poorly understood. Using a novel genetic approach, our recent study identified a conserved protein Rex1BD required for position-dependent silencing within heterochromatin repeats. We further revealed that Rex1BD interacts with the 14-3-3 protein to regulate heterochromatin silencing by linking RNAi and HDAC pathways. In this review, we discuss how Rex1BD and the 14-3-3 protein coordinate to modulate heterochromatin organization at the individual repeat level, and comment on the biological significance of the position-dependent effect in heterochromatin repeats. We also identify the knowledge gaps that still need to be unveiled in the field.
Collapse
Affiliation(s)
- Jinxin Gao
- Department of Biology, New York University, New York, New York, USA
| | - Fei Li
- Department of Biology, New York University, New York, New York, USA
| |
Collapse
|
6
|
Khanduja JS, Joh RI, Perez MM, Paulo JA, Palmieri CM, Zhang J, Gulka AOD, Haas W, Gygi SP, Motamedi M. RNA quality control factors nucleate Clr4/SUV39H and trigger constitutive heterochromatin assembly. Cell 2024; 187:3262-3283.e23. [PMID: 38815580 PMCID: PMC11227895 DOI: 10.1016/j.cell.2024.04.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 11/10/2023] [Accepted: 04/29/2024] [Indexed: 06/01/2024]
Abstract
In eukaryotes, the Suv39 family of proteins tri-methylate lysine 9 of histone H3 (H3K9me) to form constitutive heterochromatin. However, how Suv39 proteins are nucleated at heterochromatin is not fully described. In the fission yeast, current models posit that Argonaute1-associated small RNAs (sRNAs) nucleate the sole H3K9 methyltransferase, Clr4/SUV39H, to centromeres. Here, we show that in the absence of all sRNAs and H3K9me, the Mtl1 and Red1 core (MTREC)/PAXT complex nucleates Clr4/SUV39H at a heterochromatic long noncoding RNA (lncRNA) at which the two H3K9 deacetylases, Sir2 and Clr3, also accumulate by distinct mechanisms. Iterative cycles of H3K9 deacetylation and methylation spread Clr4/SUV39H from the nucleation center in an sRNA-independent manner, generating a basal H3K9me state. This is acted upon by the RNAi machinery to augment and amplify the Clr4/H3K9me signal at centromeres to establish heterochromatin. Overall, our data reveal that lncRNAs and RNA quality control factors can nucleate heterochromatin and function as epigenetic silencers in eukaryotes.
Collapse
Affiliation(s)
- Jasbeer S Khanduja
- Massachusetts General Hospital Krantz Family Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA
| | - Richard I Joh
- Massachusetts General Hospital Krantz Family Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA
| | - Monica M Perez
- Massachusetts General Hospital Krantz Family Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Christina M Palmieri
- Massachusetts General Hospital Krantz Family Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA
| | - Jingyu Zhang
- Massachusetts General Hospital Krantz Family Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA
| | - Alex O D Gulka
- Massachusetts General Hospital Krantz Family Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA
| | - Willhelm Haas
- Massachusetts General Hospital Krantz Family Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Mo Motamedi
- Massachusetts General Hospital Krantz Family Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, MA 02129, USA.
| |
Collapse
|
7
|
Ghimire P, Motamedi M, Joh R. Mathematical model for the role of multiple pericentromeric repeats on heterochromatin assembly. PLoS Comput Biol 2024; 20:e1012027. [PMID: 38598558 PMCID: PMC11034663 DOI: 10.1371/journal.pcbi.1012027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 04/22/2024] [Accepted: 03/27/2024] [Indexed: 04/12/2024] Open
Abstract
Although the length and constituting sequences for pericentromeric repeats are highly variable across eukaryotes, the presence of multiple pericentromeric repeats is one of the conserved features of the eukaryotic chromosomes. Pericentromeric heterochromatin is often misregulated in human diseases, with the expansion of pericentromeric repeats in human solid cancers. In this article, we have developed a mathematical model of the RNAi-dependent methylation of H3K9 in the pericentromeric region of fission yeast. Our model, which takes copy number as an explicit parameter, predicts that the pericentromere is silenced only if there are many copies of repeats. It becomes bistable or desilenced if the copy number of repeats is reduced. This suggests that the copy number of pericentromeric repeats alone can determine the fate of heterochromatin silencing in fission yeast. Through sensitivity analysis, we identified parameters that favor bistability and desilencing. Stochastic simulation shows that faster cell division and noise favor the desilenced state. These results show the unexpected role of pericentromeric repeat copy number in gene silencing and provide a quantitative basis for how the copy number allows or protects repetitive and unique parts of the genome from heterochromatin silencing, respectively.
Collapse
Affiliation(s)
- Puranjan Ghimire
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia, United States of America
| | - Mo Motamedi
- Massachusetts General Hospital Center for Cancer Research and Department of Medicine, Harvard Medical School, Charlestown, Boston, Massachusetts, United States of America
| | - Richard Joh
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia, United States of America
- Massey Cancer Center, Virginia Commonwealth University, Richmond Virginia, United States of America
| |
Collapse
|
8
|
Muhammad A, Sarkadi Z, van Emden T, Mazumder A, Capella M, Fekete G, Sreechakram VNS, Al-Sady B, Papp B, Barrales RR, Braun S. A systematic quantitative approach comprehensively defines domain-specific functional pathways linked to Schizosaccharomyces pombe heterochromatin regulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.13.579970. [PMID: 38405799 PMCID: PMC10888830 DOI: 10.1101/2024.02.13.579970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Heterochromatin plays a critical role in regulating gene expression and maintaining genome integrity. While structural and enzymatic components have been linked to heterochromatin establishment, a comprehensive view of the underlying pathways at diverse heterochromatin domains remains elusive. Here, we developed a systematic approach to identify factors involved in heterochromatin silencing at pericentromeres, subtelomeres, and the silent mating type locus in Schizosaccharomyces pombe. Using quantitative measures, iterative genetic screening, and domain-specific heterochromatin reporters, we identified 369 mutants with different degrees of reduced or enhanced silencing. As expected, mutations in the core heterochromatin machinery globally decreased silencing. However, most other mutants exhibited distinct qualitative and quantitative profiles that indicate domain-specific functions. For example, decreased mating type silencing was linked to mutations in heterochromatin maintenance genes, while compromised subtelomere silencing was associated with metabolic pathways. Furthermore, similar phenotypic profiles revealed shared functions for subunits within complexes. We also discovered that the uncharacterized protein Dhm2 plays a crucial role in maintaining constitutive and facultative heterochromatin, while its absence caused phenotypes akin to DNA replication-deficient mutants. Collectively, our systematic approach unveiled a landscape of domain-specific heterochromatin regulators controlling distinct states and identified Dhm2 as a previously unknown factor linked to heterochromatin inheritance and replication fidelity.
Collapse
Affiliation(s)
- Abubakar Muhammad
- Institute for Genetics, Justus-Liebig-University Giessen, Giessen, Germany
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, Planegg-Martinsried, Germany
| | - Zsuzsa Sarkadi
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
- Synthetic and Systems Biology Unit, Institute of Biochemistry, HUN-REN Biological Research Centre, Szeged, Hungary
- HCEMM-BRC Metabolic Systems Biology Lab, Szeged, Hungary
| | - Thomas van Emden
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, Planegg-Martinsried, Germany
| | - Agnisrota Mazumder
- Institute for Genetics, Justus-Liebig-University Giessen, Giessen, Germany
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
| | - Matias Capella
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
- Present address: Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Gergely Fekete
- Synthetic and Systems Biology Unit, Institute of Biochemistry, HUN-REN Biological Research Centre, Szeged, Hungary
- HCEMM-BRC Metabolic Systems Biology Lab, Szeged, Hungary
| | - Vishnu N Suma Sreechakram
- Institute for Genetics, Justus-Liebig-University Giessen, Giessen, Germany
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
| | - Bassem Al-Sady
- Department of Microbiology & Immunology, George Williams Hooper Foundation, University of California San Francisco, San Francisco, California, United States of America
| | - Balázs Papp
- Synthetic and Systems Biology Unit, Institute of Biochemistry, HUN-REN Biological Research Centre, Szeged, Hungary
- HCEMM-BRC Metabolic Systems Biology Lab, Szeged, Hungary
| | - Ramón Ramos Barrales
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
- Present address: Centro Andaluz de Biología del Desarrollo (CABD), Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas-Junta de Andalucía, Seville, Spain
| | - Sigurd Braun
- Institute for Genetics, Justus-Liebig-University Giessen, Giessen, Germany
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, Planegg-Martinsried, Germany
| |
Collapse
|
9
|
Du W, Shi G, Shan CM, Li Z, Zhu B, Jia S, Li Q, Zhang Z. Mechanisms of chromatin-based epigenetic inheritance. SCIENCE CHINA. LIFE SCIENCES 2022; 65:2162-2190. [PMID: 35792957 PMCID: PMC10311375 DOI: 10.1007/s11427-022-2120-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
Multi-cellular organisms such as humans contain hundreds of cell types that share the same genetic information (DNA sequences), and yet have different cellular traits and functions. While how genetic information is passed through generations has been extensively characterized, it remains largely obscure how epigenetic information encoded by chromatin regulates the passage of certain traits, gene expression states and cell identity during mitotic cell divisions, and even through meiosis. In this review, we will summarize the recent advances on molecular mechanisms of epigenetic inheritance, discuss the potential impacts of epigenetic inheritance during normal development and in some disease conditions, and outline future research directions for this challenging, but exciting field.
Collapse
Affiliation(s)
- Wenlong Du
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Guojun Shi
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Chun-Min Shan
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhiming Li
- Institutes of Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY, 10032, USA
| | - Bing Zhu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA.
| | - Qing Li
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China.
| | - Zhiguo Zhang
- Institutes of Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY, 10032, USA.
| |
Collapse
|
10
|
The transcription factor Atf1 lowers the transition barrier for nucleosome-mediated establishment of heterochromatin. Cell Rep 2022; 39:110828. [PMID: 35584672 DOI: 10.1016/j.celrep.2022.110828] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/09/2022] [Accepted: 04/26/2022] [Indexed: 11/22/2022] Open
Abstract
Transcription factors can exert opposite effects depending on the chromosomal context. The fission yeast transcription factor Atf1 both activates numerous genes in response to stresses and mediates heterochromatic gene silencing in the mating-type region. Investigating this context dependency, we report here that the establishment of silent heterochromatin in the mating-type region occurs at a reduced rate in the absence of Atf1 binding. Quantitative modeling accounts for the observed establishment profiles by a combinatorial recruitment of histone-modifying enzymes: locally by Atf1 at two binding sites and over the whole region by dynamically appearing heterochromatic nucleosomes, a source of which is the RNAi-dependent cenH element. In the absence of Atf1 binding, the synergy is lost, resulting in a slow rate of heterochromatin formation. The system shows how DNA-binding proteins can influence local nucleosome states and thereby potentiate long-range positive feedback on histone-modification reactions to enable heterochromatin formation over large regions in a context-dependent manner.
Collapse
|
11
|
Stirpe A, Guidotti N, Northall SJ, Kilic S, Hainard A, Vadas O, Fierz B, Schalch T. SUV39 SET domains mediate crosstalk of heterochromatic histone marks. eLife 2021; 10:62682. [PMID: 34524082 PMCID: PMC8443253 DOI: 10.7554/elife.62682] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 08/31/2021] [Indexed: 12/21/2022] Open
Abstract
The SUV39 class of methyltransferase enzymes deposits histone H3 lysine 9 di- and trimethylation (H3K9me2/3), the hallmark of constitutive heterochromatin. How these enzymes are regulated to mark specific genomic regions as heterochromatic is poorly understood. Clr4 is the sole H3K9me2/3 methyltransferase in the fission yeast Schizosaccharomyces pombe, and recent evidence suggests that ubiquitination of lysine 14 on histone H3 (H3K14ub) plays a key role in H3K9 methylation. However, the molecular mechanism of this regulation and its role in heterochromatin formation remain to be determined. Our structure-function approach shows that the H3K14ub substrate binds specifically and tightly to the catalytic domain of Clr4, and thereby stimulates the enzyme by over 250-fold. Mutations that disrupt this mechanism lead to a loss of H3K9me2/3 and abolish heterochromatin silencing similar to clr4 deletion. Comparison with mammalian SET domain proteins suggests that the Clr4 SET domain harbors a conserved sensor for H3K14ub, which mediates licensing of heterochromatin formation.
Collapse
Affiliation(s)
- Alessandro Stirpe
- Department of Molecular Biology, Faculty of Science, University of Geneva, Geneva, Switzerland
| | - Nora Guidotti
- Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Sarah J Northall
- Leicester Institute for Structural and Chemical Biology, University of Leicester, Leicester, United Kingdom.,Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| | - Sinan Kilic
- Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Alexandre Hainard
- University Medical Center, University of Geneva, Geneva, Switzerland
| | - Oscar Vadas
- School of Pharmaceutical Sciences, Faculty of Science, University of Geneva, Geneva, Switzerland
| | - Beat Fierz
- Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Thomas Schalch
- Department of Molecular Biology, Faculty of Science, University of Geneva, Geneva, Switzerland.,Leicester Institute for Structural and Chemical Biology, University of Leicester, Leicester, United Kingdom.,Department of Molecular and Cell Biology, University of Leicester, Leicester, United Kingdom
| |
Collapse
|
12
|
Habig M, Schotanus K, Hufnagel K, Happel P, Stukenbrock EH. Ago1 Affects the Virulence of the Fungal Plant Pathogen Zymoseptoria tritici. Genes (Basel) 2021; 12:1011. [PMID: 34208898 PMCID: PMC8303167 DOI: 10.3390/genes12071011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 12/04/2022] Open
Abstract
In host-pathogen interactions RNA interference (RNAi) has emerged as a pivotal mechanism to modify both, the immune responses of the host as well as the pathogenicity and virulence of the pathogen. In addition, in some fungi RNAi is also known to affect chromosome biology via its effect on chromatin conformation. Previous studies reported no effect of the RNAi machinery on the virulence of the fungal plant pathogen Zymoseptoria tritici however the role of RNAi is still poorly understood in this species. Herein, we elucidate whether the RNAi machinery is conserved within the genus Zymoseptoria. Moreover, we conduct functional analyses of Argonaute and Dicer-like proteins and test if the RNAi machinery affects chromosome stability. We show that the RNAi machinery is conserved among closely related Zymoseptoria species while an exceptional pattern of allelic diversity was possibly caused by introgression. The deletion of Ago1 reduced the ability of the fungus to produce asexual propagules in planta in a quantitative matter. Chromosome stability of the accessory chromosome of Z. tritici was not prominently affected by the RNAi machinery. These results indicate, in contrast to previous finding, a role of the RNAi pathway during host infection, but not in the stability of accessory chromosomes in Z. tritici.
Collapse
Affiliation(s)
- Michael Habig
- Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 1-11, 24118 Kiel, Germany; (M.H.); (K.S.); (K.H.)
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Klaas Schotanus
- Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 1-11, 24118 Kiel, Germany; (M.H.); (K.S.); (K.H.)
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Kim Hufnagel
- Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 1-11, 24118 Kiel, Germany; (M.H.); (K.S.); (K.H.)
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Petra Happel
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany;
| | - Eva H. Stukenbrock
- Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 1-11, 24118 Kiel, Germany; (M.H.); (K.S.); (K.H.)
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| |
Collapse
|
13
|
Reevaluating the roles of histone-modifying enzymes and their associated chromatin modifications in transcriptional regulation. Nat Genet 2020; 52:1271-1281. [PMID: 33257899 DOI: 10.1038/s41588-020-00736-4] [Citation(s) in RCA: 223] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 10/08/2020] [Indexed: 12/14/2022]
Abstract
Histone-modifying enzymes are implicated in the control of diverse DNA-templated processes including gene expression. Here, we outline historical and current thinking regarding the functions of histone modifications and their associated enzymes. One current viewpoint, based largely on correlative evidence, posits that histone modifications are instructive for transcriptional regulation and represent an epigenetic 'code'. Recent studies have challenged this model and suggest that histone marks previously associated with active genes do not directly cause transcriptional activation. Additionally, many histone-modifying proteins possess non-catalytic functions that overshadow their enzymatic activities. Given that much remains unknown regarding the functions of these proteins, the field should be cautious in interpreting loss-of-function phenotypes and must consider both cellular and developmental context. In this Perspective, we focus on recent progress relating to the catalytic and non-catalytic functions of the Trithorax-COMPASS complexes, Polycomb repressive complexes and Clr4/Suv39 histone-modifying machineries.
Collapse
|
14
|
Taglini F, Chapman E, van Nues R, Theron E, Bayne EH. Mkt1 is required for RNAi-mediated silencing and establishment of heterochromatin in fission yeast. Nucleic Acids Res 2020; 48:1239-1253. [PMID: 31822915 PMCID: PMC7026591 DOI: 10.1093/nar/gkz1157] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/12/2019] [Accepted: 11/28/2019] [Indexed: 01/04/2023] Open
Abstract
Constitutive domains of repressive heterochromatin are maintained within the fission yeast genome through self-reinforcing mechanisms involving histone methylation and small RNAs. Non-coding RNAs generated from heterochromatic regions are processed into small RNAs by the RNA interference pathway, and are subject to silencing through both transcriptional and post-transcriptional mechanisms. While the pathways involved in maintenance of the repressive heterochromatin state are reasonably well understood, less is known about the requirements for its establishment. Here, we describe a novel role for the post-transcriptional regulatory factor Mkt1 in establishment of heterochromatin at pericentromeres in fission yeast. Loss of Mkt1 does not affect maintenance of existing heterochromatin, but does affect its recovery following depletion, as well as de novo establishment of heterochromatin on a mini-chromosome. Pathway dissection revealed that Mkt1 is required for RNAi-mediated post-transcriptional silencing, downstream of small RNA production. Mkt1 physically associates with pericentromeric transcripts, and is additionally required for maintenance of silencing and heterochromatin at centromeres when transcriptional silencing is impaired. Our findings provide new insight into the mechanism of RNAi-mediated post-transcriptional silencing in fission yeast, and unveil an important role for post-transcriptional silencing in establishment of heterochromatin that is dispensable when full transcriptional silencing is imposed.
Collapse
Affiliation(s)
- Francesca Taglini
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | - Elliott Chapman
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | - Rob van Nues
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | - Emmanuelle Theron
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | - Elizabeth H Bayne
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| |
Collapse
|
15
|
Liberman N, Wang SY, Greer EL. Transgenerational epigenetic inheritance: from phenomena to molecular mechanisms. Curr Opin Neurobiol 2019; 59:189-206. [PMID: 31634674 DOI: 10.1016/j.conb.2019.09.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 09/11/2019] [Indexed: 02/07/2023]
Abstract
Inherited information not encoded in the DNA sequence can regulate a variety of complex phenotypes. However, how this epigenetic information escapes the typical epigenetic erasure that occurs upon fertilization and how it regulates behavior is still unclear. Here we review recent examples of brain related transgenerational epigenetic inheritance and delineate potential molecular mechanisms that could regulate how non-genetic information could be transmitted.
Collapse
Affiliation(s)
- Noa Liberman
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston MA 02115, USA
| | - Simon Yuan Wang
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston MA 02115, USA
| | - Eric Lieberman Greer
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston MA 02115, USA.
| |
Collapse
|
16
|
Oya E, Nakagawa R, Yoshimura Y, Tanaka M, Nishibuchi G, Machida S, Shirai A, Ekwall K, Kurumizaka H, Tagami H, Nakayama J. H3K14 ubiquitylation promotes H3K9 methylation for heterochromatin assembly. EMBO Rep 2019; 20:e48111. [PMID: 31468675 PMCID: PMC6776926 DOI: 10.15252/embr.201948111] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 08/07/2019] [Accepted: 08/09/2019] [Indexed: 12/28/2022] Open
Abstract
The methylation of histone H3 at lysine 9 (H3K9me), performed by the methyltransferase Clr4/SUV39H, is a key event in heterochromatin assembly. In fission yeast, Clr4, together with the ubiquitin E3 ligase Cul4, forms the Clr4 methyltransferase complex (CLRC), whose physiological targets and biological role are currently unclear. Here, we show that CLRC-dependent H3 ubiquitylation regulates Clr4's methyltransferase activity. Affinity-purified CLRC ubiquitylates histone H3, and mass spectrometric and mutation analyses reveal that H3 lysine 14 (H3K14) is the preferred target of the complex. Chromatin immunoprecipitation analysis shows that H3K14 ubiquitylation (H3K14ub) is closely associated with H3K9me-enriched chromatin. Notably, the CLRC-mediated H3 ubiquitylation promotes H3K9me by Clr4, suggesting that H3 ubiquitylation is intimately linked to the establishment and/or maintenance of H3K9me. These findings demonstrate a cross-talk mechanism between histone ubiquitylation and methylation that is involved in heterochromatin assembly.
Collapse
Affiliation(s)
- Eriko Oya
- Graduate School of Natural SciencesNagoya City UniversityNagoyaJapan
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
- Present address:
Faculty of Science and EngineeringChuo UniversityBunkyo‐ku, TokyoJapan
| | - Reiko Nakagawa
- Laboratory for PhyloinformaticsRIKEN Center for Biosystems Dynamics ResearchKobeJapan
| | - Yuriko Yoshimura
- Division of Chromatin RegulationNational Institute for Basic BiologyOkazakiJapan
| | - Mayo Tanaka
- Division of Chromatin RegulationNational Institute for Basic BiologyOkazakiJapan
| | - Gohei Nishibuchi
- Graduate School of Natural SciencesNagoya City UniversityNagoyaJapan
- Present address:
Graduate School of ScienceOsaka UniversityToyonakaJapan
| | - Shinichi Machida
- Laboratory of Structural BiologyGraduate School of Advanced Science and EngineeringWaseda UniversityShinjuku‐ku, TokyoJapan
- Present address:
Institute of Human GeneticsCNRS UMR 9002MontpellierFrance
| | | | - Karl Ekwall
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
| | - Hitoshi Kurumizaka
- Laboratory of Structural BiologyGraduate School of Advanced Science and EngineeringWaseda UniversityShinjuku‐ku, TokyoJapan
- Laboratory of Chromatin Structure and FunctionInstitute for Quantitative BiosciencesThe University of TokyoBunkyo‐ku, TokyoJapan
| | - Hideaki Tagami
- Graduate School of Natural SciencesNagoya City UniversityNagoyaJapan
| | - Jun‐ichi Nakayama
- Graduate School of Natural SciencesNagoya City UniversityNagoyaJapan
- Division of Chromatin RegulationNational Institute for Basic BiologyOkazakiJapan
- Department of Basic BiologySchool of Life ScienceThe Graduate University for Advanced Studies (SOKENDAI)OkazakiJapan
| |
Collapse
|
17
|
Farooq Z, Abdullah E, Banday S, Ganai SA, Rashid R, Mushtaq A, Rashid S, Altaf M. Vigilin protein Vgl1 is required for heterochromatin-mediated gene silencing in Schizosaccharomyces pombe. J Biol Chem 2019; 294:18029-18040. [PMID: 31554660 DOI: 10.1074/jbc.ra119.009262] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 08/28/2019] [Indexed: 11/06/2022] Open
Abstract
Heterochromatin is a conserved feature of eukaryotic genomes and regulates various cellular processes, including gene silencing, chromosome segregation, and maintenance of genome stability. In the fission yeast Schizosaccharomyces pombe, heterochromatin formation involves methylation of lysine 9 in histone H3 (H3K9), which recruits Swi6/HP1 proteins to heterochromatic loci. The Swi6/HP1-H3K9me3 chromatin complex lies at the center of heterochromatic macromolecular assemblies and mediates many functions of heterochromatin by recruiting a diverse set of regulators. However, additional factors may be required for proper heterochromatin organization, but they are not fully known. Here, using several molecular and biochemical approaches, we report that Vgl1, a member of a large family of multiple KH-domain proteins, collectively known as vigilins, is indispensable for the heterochromatin-mediated gene silencing in S. pombe ChIP analysis revealed that Vgl1 binds to pericentromeric heterochromatin in an RNA-dependent manner and that Vgl1 deletion leads to loss of H3K9 methylation and Swi6 recruitment to centromeric and telomeric heterochromatic loci. Furthermore, we show that Vgl1 interacts with the H3K9 methyltransferase, Clr4, and that loss of Vgl1 impairs Clr4 recruitment to heterochromatic regions of the genome. These findings uncover a novel role for Vgl1 as a key regulator in heterochromatin-mediated gene silencing in S. pombe.
Collapse
Affiliation(s)
- Zeenat Farooq
- Chromatin and Epigenetics Lab, Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir 190006, India
| | - Ehsaan Abdullah
- Chromatin and Epigenetics Lab, Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir 190006, India
| | - Shahid Banday
- Chromatin and Epigenetics Lab, Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir 190006, India
| | - Shabir Ahmad Ganai
- Chromatin and Epigenetics Lab, Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir 190006, India
| | - Romana Rashid
- Chromatin and Epigenetics Lab, Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir 190006, India
| | - Arjamand Mushtaq
- Chromatin and Epigenetics Lab, Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir 190006, India
| | - Samia Rashid
- Chromatin and Epigenetics Lab, Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir 190006, India
| | - Mohammad Altaf
- Chromatin and Epigenetics Lab, Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir 190006, India.
| |
Collapse
|
18
|
Bhattacharjee S, Roche B, Martienssen RA. RNA-induced initiation of transcriptional silencing (RITS) complex structure and function. RNA Biol 2019; 16:1133-1146. [PMID: 31213126 DOI: 10.1080/15476286.2019.1621624] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Heterochromatic regions of the genome are epigenetically regulated to maintain a heritable '"silent state"'. In fission yeast and other organisms, epigenetic silencing is guided by nascent transcripts, which are targeted by the RNA interference pathway. The key effector complex of the RNA interference pathway consists of small interfering RNA molecules (siRNAs) associated with Argonaute, assembled into the RNA-induced transcriptional silencing (RITS) complex. This review focuses on our current understanding of how RITS promotes heterochromatin formation, and in particular on the role of Argonaute-containing complexes in many other functions such as quelling, release of RNA polymerases, cellular quiescence and genome defense.
Collapse
Affiliation(s)
- Sonali Bhattacharjee
- a Cold Spring Harbor Laboratory, Howard Hughes Medical Institute , Cold Spring Harbor , NY , USA
| | - Benjamin Roche
- a Cold Spring Harbor Laboratory, Howard Hughes Medical Institute , Cold Spring Harbor , NY , USA
| | - Robert A Martienssen
- a Cold Spring Harbor Laboratory, Howard Hughes Medical Institute , Cold Spring Harbor , NY , USA
| |
Collapse
|
19
|
Thankam FG, Boosani CS, Dilisio MF, Agrawal DK. Epigenetic mechanisms and implications in tendon inflammation (Review). Int J Mol Med 2019; 43:3-14. [PMID: 30387824 PMCID: PMC6257858 DOI: 10.3892/ijmm.2018.3961] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 09/18/2018] [Indexed: 12/18/2022] Open
Abstract
Cellular inflammation is not just an immediate response following pathogenic infections or resulting from damage due to injury, it is also associated with normal physiological functions, including wound healing and tissue repair. The existence of such a definitive role in normal physiology and in disease pathology indicates the presence of a regulatory mechanism that is tightly controlled in normal cells. A tight control over gene expression is associated with regulatory mechanisms in the cells, which can be either inducible or epigenetic. Among other intracellular mechanisms that contribute to epigenetic gene regulation, DNA methylation has been shown to maintain a tight control over gene expression through the actions of DNA methyltransferases (DNMTs). With a clear role in developmental and tissue‑specific temporal gene regulation, the involvement of DNMTs is evident in normal and pathological conditions. In this review article, inflammation in tendons associated with disease pathology and tissue repair or regeneration at the musculoskeletal joints is critically reviewed. More specifically, the review focuses on known epigenetic mechanisms and their role in the clinical presentation of the disease in human joint disorders associated with tendon inflammation, with an emphasis on the gene regulatory mechanisms that are controlled through DNA methylation, histone deacetylation, and microRNAs.
Collapse
Affiliation(s)
| | | | - Matthew F. Dilisio
- Department of Orthopedic Surgery, Creighton University School of Medicine, Omaha, NE 68178, USA
| | | |
Collapse
|
20
|
Czech B, Munafò M, Ciabrelli F, Eastwood EL, Fabry MH, Kneuss E, Hannon GJ. piRNA-Guided Genome Defense: From Biogenesis to Silencing. Annu Rev Genet 2018; 52:131-157. [PMID: 30476449 PMCID: PMC10784713 DOI: 10.1146/annurev-genet-120417-031441] [Citation(s) in RCA: 362] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
PIWI-interacting RNAs (piRNAs) and their associated PIWI clade Argonaute proteins constitute the core of the piRNA pathway. In gonadal cells, this conserved pathway is crucial for genome defense, and its main function is to silence transposable elements. This is achieved through posttranscriptional and transcriptional gene silencing. Precursors that give rise to piRNAs require specialized transcription and transport machineries because piRNA biogenesis is a cytoplasmic process. The ping-pong cycle, a posttranscriptional silencing mechanism, combines the cleavage-dependent silencing of transposon RNAs with piRNA production. PIWI proteins also function in the nucleus, where they scan for nascent target transcripts with sequence complementarity, instructing transcriptional silencing and deposition of repressive chromatin marks at transposon loci. Although studies have revealed numerous factors that participate in each branch of the piRNA pathway, the precise molecular roles of these factors often remain unclear. In this review, we summarize our current understanding of the mechanisms involved in piRNA biogenesis and function.
Collapse
Affiliation(s)
- Benjamin Czech
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Marzia Munafò
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Filippo Ciabrelli
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Evelyn L Eastwood
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Martin H Fabry
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Emma Kneuss
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Gregory J Hannon
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| |
Collapse
|
21
|
Watts BR, Wittmann S, Wery M, Gautier C, Kus K, Birot A, Heo DH, Kilchert C, Morillon A, Vasiljeva L. Histone deacetylation promotes transcriptional silencing at facultative heterochromatin. Nucleic Acids Res 2018; 46:5426-5440. [PMID: 29618061 PMCID: PMC6009587 DOI: 10.1093/nar/gky232] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 03/14/2018] [Accepted: 03/19/2018] [Indexed: 12/25/2022] Open
Abstract
It is important to accurately regulate the expression of genes involved in development and environmental response. In the fission yeast Schizosaccharomyces pombe, meiotic genes are tightly repressed during vegetative growth. Despite being embedded in heterochromatin these genes are transcribed and believed to be repressed primarily at the level of RNA. However, the mechanism of facultative heterochromatin formation and the interplay with transcription regulation is not understood. We show genome-wide that HDAC-dependent histone deacetylation is a major determinant in transcriptional silencing of facultative heterochromatin domains. Indeed, mutation of class I/II HDACs leads to increased transcription of meiotic genes and accumulation of their mRNAs. Mechanistic dissection of the pho1 gene where, in response to phosphate, transient facultative heterochromatin is established by overlapping lncRNA transcription shows that the Clr3 HDAC contributes to silencing independently of SHREC, but in an lncRNA-dependent manner. We propose that HDACs promote facultative heterochromatin by establishing alternative transcriptional silencing.
Collapse
Affiliation(s)
- Beth R Watts
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Sina Wittmann
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Maxime Wery
- ncRNA, epigenetic and genome fluidity, Institut Curie, PSL Research University, CNRS UMR 3244, Université Pierre et Marie Curie, 75248 Paris Cedex 05, France
| | - Camille Gautier
- ncRNA, epigenetic and genome fluidity, Institut Curie, PSL Research University, CNRS UMR 3244, Université Pierre et Marie Curie, 75248 Paris Cedex 05, France
| | - Krzysztof Kus
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Adrien Birot
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Dong-Hyuk Heo
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Cornelia Kilchert
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
- Institut für Biochemie, Heinrich-Buff-Ring 17, 35392 Gießen, Germany
| | - Antonin Morillon
- ncRNA, epigenetic and genome fluidity, Institut Curie, PSL Research University, CNRS UMR 3244, Université Pierre et Marie Curie, 75248 Paris Cedex 05, France
| | - Lidia Vasiljeva
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| |
Collapse
|
22
|
Abstract
Heterochromatin is a key architectural feature of eukaryotic chromosomes, which endows particular genomic domains with specific functional properties. The capacity of heterochromatin to restrain the activity of mobile elements, isolate DNA repair in repetitive regions and ensure accurate chromosome segregation is crucial for maintaining genomic stability. Nucleosomes at heterochromatin regions display histone post-translational modifications that contribute to developmental regulation by restricting lineage-specific gene expression. The mechanisms of heterochromatin establishment and of heterochromatin maintenance are separable and involve the ability of sequence-specific factors bound to nascent transcripts to recruit chromatin-modifying enzymes. Heterochromatin can spread along the chromatin from nucleation sites. The propensity of heterochromatin to promote its own spreading and inheritance is counteracted by inhibitory factors. Because of its importance for chromosome function, heterochromatin has key roles in the pathogenesis of various human diseases. In this Review, we discuss conserved principles of heterochromatin formation and function using selected examples from studies of a range of eukaryotes, from yeast to human, with an emphasis on insights obtained from unicellular model organisms.
Collapse
|
23
|
Huang Y, Zou Y, Lin L, Ma X, Huang X. Effect of BIX-01294 on proliferation, apoptosis and histone methylation of acute T lymphoblastic leukemia cells. Leuk Res 2017; 62:34-39. [PMID: 28982057 DOI: 10.1016/j.leukres.2017.09.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 08/04/2017] [Accepted: 09/24/2017] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine effect of G9a inhibitor BIX-01294 on proliferation, apoptosis and histone methylation of acute T lymphoblastic leukemia cells (MOLT-4 and Jurkat) and to explore the underlying mechanism. METHODS Cell proliferation was detected by MTT assay and apoptosis and cell cycle were measured by flow cytometry. Western blot was performed to determine expression of caspase-3, Bcl-2, Bax, P21, P15 and DNMT1 as well as levels of histone H3 acetylation, histone H3K9 mono- di- and tri-methylation. RESULTS BIX-01294 inhibits expression of Bcl-2, upregulates expression of Bax and caspase-3 and induces cell apoptosis. BIX-01294 upregulates cell cycle inhibitor P21 expression and induces cell cycle arrest in the phase G0/G1. Furthermore, BIX-01294 suppresses expression of DNA demethylase DNMT1 and promotes expression of tumor suppressor protein P15, thereby inhibiting proliferation of MOLT-4 and Jurkat cells. BIX-01294 downregulates histone H3K9 mono- and di-methylation levels and has no effect on H3K9 trimethylation and histone H3 acetylation. CONCLUSION Taken together, our results indicate that by regulating H3K9 methylation and cell cycle, BIX-01294 inhibits the proliferation and induces apoptosis of acute T lymphoblastic leukemia cells.
Collapse
Affiliation(s)
- Yiqun Huang
- Department of Hematology, Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou, Fujian 363000, China
| | - Yong Zou
- Department of Hematology, Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou, Fujian 363000, China
| | - Luhui Lin
- Department of Hematology, Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou, Fujian 363000, China
| | - Xudong Ma
- Department of Hematology, Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou, Fujian 363000, China
| | - Xiaohong Huang
- Department of Pharmacy, Zhangzhou Affiliated Hospital of Fujian Medical University, No. 59 Shengli Road, Zhangzhou, Fujian 363000, China.
| |
Collapse
|
24
|
Abstract
In modern molecular biology, RNA has emerged as a versatile macromolecule capable of mediating an astonishing number of biological functions beyond its role as a transient messenger of genetic information. The recent discovery and functional analyses of new classes of noncoding RNAs (ncRNAs) have revealed their widespread use in many pathways, including several in the nucleus. This Review focuses on the mechanisms by which nuclear ncRNAs directly contribute to the maintenance of genome stability. We discuss how ncRNAs inhibit spurious recombination among repetitive DNA elements, repress mobilization of transposable elements (TEs), template or bridge DNA double-strand breaks (DSBs) during repair, and direct developmentally regulated genome rearrangements in some ciliates. These studies reveal an unexpected repertoire of mechanisms by which ncRNAs contribute to genome stability and even potentially fuel evolution by acting as templates for genome modification.
Collapse
|
25
|
Unique roles for histone H3K9me states in RNAi and heritable silencing of transcription. Nature 2017; 547:463-467. [PMID: 28682306 PMCID: PMC5576860 DOI: 10.1038/nature23267] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 06/15/2017] [Indexed: 12/23/2022]
Abstract
Heterochromatic DNA domains play important roles in regulation of gene expression and maintenance of genome stability by silencing repetitive DNA elements and transposons. From fission yeast to mammals, heterochromatin assembly at DNA repeats involves the activity of small noncoding RNAs (sRNAs) associated with the RNA interference (RNAi) pathway1–9. Typically, sRNAs, originating from long noncoding RNAs, guide Argonaute-containing effector complexes to complementary nascent RNAs to initiate histone H3 lysine 9 di- and tri-methylation (H3K9me2 and H3K9me3, respectively) and heterochromatin formation10–17. H3K9me is in turn required for recruitment of RNAi to chromatin to promote sRNA amplification11,15,18. Yet, how heterochromatin formation, which silences transcription, can proceed by a co-transcriptional mechanism that also promotes sRNA generation remains paradoxical. Here, using Clr4, the fission yeast S. pombe homolog of mammalian SUV39H H3K9 methyltransferases, we designed active site mutations that block H3K9me3, but allow H3K9me2 catalysis. We show that H3K9me2 defines a functionally distinct heterochromatin state that is sufficient for RNAi-dependent co-transcriptional gene silencing (CTGS) at pericentromeric DNA repeats. Unlike H3K9me3 domains, which are transcriptionally silent, H3K9me2 domains are transcriptionally active, contain modifications associated with euchromatic transcription, and couple RNAi-mediated transcript degradation to the establishment of H3K9me domains. The two H3K9me states recruit reader proteins with different efficiencies, explaining their different downstream silencing functions. Furthermore, transition from H3K9me2 to H3K9me3 is required for RNAi-independent epigenetic inheritance of H3K9me domains. Our findings demonstrate that H3K9me2 and H3K9me3 define functionally distinct chromatin states and uncover a mechanism for formation of transcriptionally permissive heterochromatin that is compatible with its broadly conserved role in sRNA-mediated genome defense.
Collapse
|
26
|
Tailing and degradation of Argonaute-bound small RNAs protect the genome from uncontrolled RNAi. Nat Commun 2017; 8:15332. [PMID: 28541282 PMCID: PMC5458512 DOI: 10.1038/ncomms15332] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 03/21/2017] [Indexed: 12/30/2022] Open
Abstract
RNAi is a conserved mechanism in which small RNAs induce silencing of complementary targets. How Argonaute-bound small RNAs are targeted for degradation is not well understood. We show that the adenyl-transferase Cid14, a member of the TRAMP complex, and the uridyl-transferase Cid16 add non-templated nucleotides to Argonaute-bound small RNAs in fission yeast. The tailing of Argonaute-bound small RNAs recruits the 3'-5' exonuclease Rrp6 to degrade small RNAs. Failure in degradation of Argonaute-bound small RNAs results in accumulation of 'noise' small RNAs on Argonaute and targeting of diverse euchromatic genes by RNAi. To protect themselves from uncontrolled RNAi, cid14Δ cells exploit the RNAi machinery and silence genes essential for RNAi itself, which is required for their viability. Our data indicate that surveillance of Argonaute-bound small RNAs by Cid14/Cid16 and the exosome protects the genome from uncontrolled RNAi and reveal a rapid RNAi-based adaptation to stress conditions.
Collapse
|
27
|
Clr4 specificity and catalytic activity beyond H3K9 methylation. Biochimie 2017; 135:83-88. [DOI: 10.1016/j.biochi.2017.01.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 01/26/2017] [Indexed: 12/13/2022]
|
28
|
Penke TJR, McKay DJ, Strahl BD, Matera AG, Duronio RJ. Direct interrogation of the role of H3K9 in metazoan heterochromatin function. Genes Dev 2016; 30:1866-80. [PMID: 27566777 PMCID: PMC5024684 DOI: 10.1101/gad.286278.116] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 08/05/2016] [Indexed: 11/24/2022]
Abstract
A defining feature of heterochromatin is methylation of Lys9 of histone H3 (H3K9me), a binding site for heterochromatin protein 1 (HP1). Penke et al. generated and analyzed H3K9R mutant flies, separating the functions of H3K9 and nonhistone substrates of H3K9 methyltransferases. A defining feature of heterochromatin is methylation of Lys9 of histone H3 (H3K9me), a binding site for heterochromatin protein 1 (HP1). Although H3K9 methyltransferases and HP1 are necessary for proper heterochromatin structure, the specific contribution of H3K9 to heterochromatin function and animal development is unknown. Using our recently developed platform to engineer histone genes in Drosophila, we generated H3K9R mutant flies, separating the functions of H3K9 and nonhistone substrates of H3K9 methyltransferases. Nucleosome occupancy and HP1a binding at pericentromeric heterochromatin are markedly decreased in H3K9R mutants. Despite these changes in chromosome architecture, a small percentage of H3K9R mutants complete development. Consistent with this result, expression of most protein-coding genes, including those within heterochromatin, is similar between H3K9R and controls. In contrast, H3K9R mutants exhibit increased open chromatin and transcription from piRNA clusters and transposons, resulting in transposon mobilization. Hence, transposon silencing is a major developmental function of H3K9.
Collapse
Affiliation(s)
- Taylor J R Penke
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Daniel J McKay
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Brian D Strahl
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - A Gregory Matera
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Robert J Duronio
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA; Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| |
Collapse
|
29
|
Yu Y, Zhou H, Deng X, Wang W, Lu H. Set3 contributes to heterochromatin integrity by promoting transcription of subunits of Clr4-Rik1-Cul4 histone methyltransferase complex in fission yeast. Sci Rep 2016; 6:31752. [PMID: 27538348 PMCID: PMC4990937 DOI: 10.1038/srep31752] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/25/2016] [Indexed: 02/05/2023] Open
Abstract
Heterochromatin formation in fission yeast depends on RNAi machinery and histone-modifying enzymes. One of the key histone-modifying complexes is Clr4-Rik1-Cul4 methyltransferase complex (CLRC), which mediates histone H3K9 methylation, a hallmark for heterochromatin. CLRC is composed of the Clr4 histone methyltransferase, Rik1, Raf1, Raf2 and Pcu4. However, transcriptional regulation of the CLRC subunits is not well understood. In this study, we identified Set3, a core subunit of the Set3/Hos2 histone deacetylase complex (Set3C), as a contributor to the integrity and silencing of heterochromatin at centromeres, telomeres and silent mating-type locus. This novel role of Set3 relies on its PHD finger, but is independent of deacetylase activity or structural integrity of Set3C. Set3 is not located to the centromeric region. Instead, Set3 is targeted to the promoters of clr4+ and rik1+, probably through its PHD finger. Set3 promotes transcription of clr4+ and rik1+. Consistently, the protein levels of Clr4 and Rik1 were reduced in the set3Δ mutant. The heterochromatin silencing defect in the set3Δ mutant could be rescued by overexpressing of clr4+ or rik1+. Our study suggests transcriptional activation of essential heterochromatin factors underlies the tight regulation of heterochromatin integrity.
Collapse
Affiliation(s)
- Yao Yu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.,Shanghai Engineering Research Center Of Industrial Microorganisms, Shanghai, 200438, China
| | - Huan Zhou
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.,Shanghai Engineering Research Center Of Industrial Microorganisms, Shanghai, 200438, China
| | - Xiaolong Deng
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.,Shanghai Engineering Research Center Of Industrial Microorganisms, Shanghai, 200438, China
| | - Wenchao Wang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.,Shanghai Engineering Research Center Of Industrial Microorganisms, Shanghai, 200438, China
| | - Hong Lu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.,Shanghai Engineering Research Center Of Industrial Microorganisms, Shanghai, 200438, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, 200237, China
| |
Collapse
|
30
|
Jain R, Iglesias N, Moazed D. Distinct Functions of Argonaute Slicer in siRNA Maturation and Heterochromatin Formation. Mol Cell 2016; 63:191-205. [PMID: 27397687 PMCID: PMC5576859 DOI: 10.1016/j.molcel.2016.05.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 05/05/2016] [Accepted: 05/26/2016] [Indexed: 11/16/2022]
Abstract
Small-RNA (sRNA)-guided transcriptional gene silencing by Argonaute (Ago)-containing complexes is fundamental to genome integrity and epigenetic inheritance. The RNA cleavage ("Slicer") activity of Argonaute has been implicated in both sRNA maturation and target RNA cleavage. Typically, Argonaute slices and releases the passenger strand of duplex sRNA to generate active silencing complexes, but it remains unclear whether slicing of target nascent RNAs, or other RNAi components, also contributes to downstream transcriptional silencing. Here, we develop a strategy for loading the fission yeast Ago1 with a single-stranded sRNA guide, which bypasses the requirement for slicer activity in generation of active silencing complexes. We show that slicer-defective Ago1 can mediate secondary sRNA generation, H3K9 methylation, and silencing similar to or better than wild-type and associates with chromatin more efficiently. The results define an ancient and minimal sRNA-mediated chromatin silencing mechanism, which resembles the germline-specific sRNA-dependent transcriptional silencing pathways in Drosophila and mammals.
Collapse
Affiliation(s)
- Ruchi Jain
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Nahid Iglesias
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Danesh Moazed
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
31
|
Nucleation and spreading of a heterochromatic domain in fission yeast. Nat Commun 2016; 7:11518. [PMID: 27167753 PMCID: PMC4865850 DOI: 10.1038/ncomms11518] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 04/05/2016] [Indexed: 12/28/2022] Open
Abstract
Outstanding questions in the chromatin field bear on how large heterochromatin domains are formed in space and time. Positive feedback, where histone-modifying enzymes are attracted to chromosomal regions displaying the modification they catalyse, is believed to drive the formation of these domains; however, few quantitative studies are available to assess this hypothesis. Here we quantified the de novo establishment of a naturally occurring ∼20-kb heterochromatin domain in fission yeast through single-cell analyses, measuring the kinetics of heterochromatin nucleation in a region targeted by RNAi and its subsequent expansion. We found that nucleation of heterochromatin is stochastic and can take from one to ten cell generations. Further silencing of the full region takes another one to ten generations. Quantitative modelling of the observed kinetics emphasizes the importance of local feedback, where a nucleosome-bound enzyme modifies adjacent nucleosomes, combined with a feedback where recruited enzymes can act at a distance. Chromosomes contain large heterochromatin domains. Here, the authors measure the kinetics of heterochromatin formation in fission yeast and show both global and local feedbacks by nucleosome-bound enzymes are important for formation and stability of the large heterochromatin domains.
Collapse
|
32
|
Plasmodium falciparum PfSET7: enzymatic characterization and cellular localization of a novel protein methyltransferase in sporozoite, liver and erythrocytic stage parasites. Sci Rep 2016; 6:21802. [PMID: 26902486 PMCID: PMC4763181 DOI: 10.1038/srep21802] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 02/01/2016] [Indexed: 02/07/2023] Open
Abstract
Epigenetic control via reversible histone methylation regulates transcriptional activation throughout the malaria parasite genome, controls the repression of multi-copy virulence gene families and determines sexual stage commitment. Plasmodium falciparum encodes ten predicted SET domain-containing protein methyltransferases, six of which have been shown to be refractory to knock-out in blood stage parasites. We have expressed and purified the first recombinant malaria methyltransferase in sufficient quantities to perform a full enzymatic characterization and reveal the ill-defined PfSET7 is an AdoMet-dependent histone H3 lysine methyltransferase with highest activity towards lysines 4 and 9. Steady-state kinetics of the PfSET7 enzyme are similar to previously characterized histone methyltransferase enzymes from other organisms, however, PfSET7 displays specific protein substrate preference towards nucleosomes with pre-existing histone H3 lysine 14 acetylation. Interestingly, PfSET7 localizes to distinct cytoplasmic foci adjacent to the nucleus in erythrocytic and liver stage parasites, and throughout the cytoplasm in salivary gland sporozoites. Characterized recombinant PfSET7 now allows for target based inhibitor discovery. Specific PfSET7 inhibitors can aid in further investigating the biological role of this specific methyltransferase in transmission, hepatic and blood stage parasites, and may ultimately lead to the development of suitable antimalarial drug candidates against this novel class of essential parasite enzymes.
Collapse
|
33
|
Abstract
SUMMARY The involvement of RNA interference (RNAi) in heterochromatin formation has become clear largely through studies in the fission yeast Schizosaccharomyces pombe and plants like Arabidopsis thaliana. This article discusses how heterochromatic small interfering RNAs are produced and how the RNAi machinery participates in the formation and function of heterochromatin.
Collapse
Affiliation(s)
| | - Danesh Moazed
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115-5730
| |
Collapse
|
34
|
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: 142] [Impact Index Per Article: 14.2] [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.
Collapse
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
| |
Collapse
|
35
|
Abstract
FLAG is an affinity tag widely used for rapid and highly specific one-step protein purification. Native elution of protein from anti-FLAG antibody resins allows the identification of protein and nucleic acid binding partners and functional analysis using biochemical activity assays.
Collapse
Affiliation(s)
- Erica Gerace
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Danesh Moazed
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
| |
Collapse
|
36
|
Abstract
This protocol outlines a procedure for testing whether two proteins interact. A target protein will be immunoprecipitated using an antibody that recognizes it (or a tagged version of the protein). The immunoprecipitated material will be separated by SDS-PAGE and analyzed by Western blotting to assess the presence of a candidate interacting protein(s).
Collapse
Affiliation(s)
- Erica Gerace
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Danesh Moazed
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
| |
Collapse
|
37
|
Small-RNA loading licenses Argonaute for assembly into a transcriptional silencing complex. Nat Struct Mol Biol 2015; 22:328-35. [PMID: 25730778 DOI: 10.1038/nsmb.2979] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Accepted: 01/31/2015] [Indexed: 12/29/2022]
Abstract
Argonautes and their small-RNA cofactors form the core effectors of ancient and diverse gene-silencing mechanisms whose roles include regulation of gene expression and defense against foreign genetic elements. Although Argonautes generally act within multisubunit complexes, what governs their assembly into these machineries is not well defined. Here, we show that loading of small RNAs onto Argonaute is a checkpoint for Argonaute's association with conserved GW-protein components of silencing complexes. We demonstrate that the Argonaute small interfering RNA chaperone (ARC) complex mediates loading of small RNAs onto Ago1 in Schizosaccharomyces pombe and that deletion of its subunits, or mutations in Ago1 that prevent small-RNA loading, abolish the assembly of the GW protein-containing RNA-induced transcriptional silencing (RITS) complex. Our studies uncover a mechanism that ensures that Argonaute loading precedes RITS assembly and thereby averts the formation of inert and potentially deleterious complexes.
Collapse
|
38
|
Abstract
Diverse classes of RNA, ranging from small to long non-coding RNAs, have emerged as key regulators of gene expression, genome stability and defence against foreign genetic elements. Small RNAs modify chromatin structure and silence transcription by guiding Argonaute-containing complexes to complementary nascent RNA scaffolds and then mediating the recruitment of histone and DNA methyltransferases. In addition, recent advances suggest that chromatin-associated long non-coding RNA scaffolds also recruit chromatin-modifying complexes independently of small RNAs. These co-transcriptional silencing mechanisms form powerful RNA surveillance systems that detect and silence inappropriate transcription events, and provide a memory of these events via self-reinforcing epigenetic loops.
Collapse
Affiliation(s)
- Daniel Holoch
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA
| | - Danesh Moazed
- Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA
| |
Collapse
|
39
|
Herz HM, Morgan M, Gao X, Jackson J, Rickels R, Swanson SK, Florens L, Washburn MP, Eissenberg JC, Shilatifard A. Histone H3 lysine-to-methionine mutants as a paradigm to study chromatin signaling. Science 2014; 345:1065-70. [PMID: 25170156 DOI: 10.1126/science.1255104] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Histone H3 lysine(27)-to-methionine (H3K27M) gain-of-function mutations occur in highly aggressive pediatric gliomas. We established a Drosophila animal model for the pathogenic histone H3K27M mutation and show that its overexpression resembles polycomb repressive complex 2 (PRC2) loss-of-function phenotypes, causing derepression of PRC2 target genes and developmental perturbations. Similarly, an H3K9M mutant depletes H3K9 methylation levels and suppresses position-effect variegation in various Drosophila tissues. The histone H3K9 demethylase KDM3B/JHDM2 associates with H3K9M-containing nucleosomes, and its misregulation in Drosophila results in changes of H3K9 methylation levels and heterochromatic silencing defects. We have established histone lysine-to-methionine mutants as robust in vivo tools for inhibiting methylation pathways that also function as biochemical reagents for capturing site-specific histone-modifying enzymes, thus providing molecular insight into chromatin signaling pathways.
Collapse
Affiliation(s)
- Hans-Martin Herz
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
| | - Marc Morgan
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
| | - Xin Gao
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
| | - Jessica Jackson
- Saint Louis University School of Medicine, Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis, MO, USA
| | - Ryan Rickels
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
| | - Selene K Swanson
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
| | - Laurence Florens
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
| | - Michael P Washburn
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA. Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Joel C Eissenberg
- Saint Louis University School of Medicine, Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis, MO, USA
| | - Ali Shilatifard
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA.
| |
Collapse
|
40
|
White SA, Buscaino A, Sanchez-Pulido L, Ponting CP, Nowicki MW, Allshire RC. The RFTS domain of Raf2 is required for Cul4 interaction and heterochromatin integrity in fission yeast. PLoS One 2014; 9:e104161. [PMID: 25090107 PMCID: PMC4121317 DOI: 10.1371/journal.pone.0104161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/11/2014] [Indexed: 11/18/2022] Open
Abstract
Centromeric heterochromatin assembly in fission yeast is critical for faithful chromosome segregation at mitosis. Its assembly requires a concerted pathway of events whereby the RNA interference (RNAi) pathway guides H3K9 methylation to target sequences. H3K9 methylation, a hallmark of heterochromatin structure, is mediated by the single histone methyltransferase Clr4 (equivalent to metazoan Suv3-9), a component of the CLRC complex. Loss of or defects in CLRC components disrupts heterochromatin formation due to loss of H3K9 methylation, thus an intact, fully functional CLRC complex is required for heterochromatin integrity. Despite its importance, little is known about the contribution of the CLRC component Raf2 to H3K9 methylation and heterochromatin assembly. We demonstrate that Raf2 is concentrated at centromeres and contrary to other analyses, we find that loss of Raf2 does not affect CENP-ACnp1 localisation or recruitment to centromeres. Our sequence alignments show that Raf2 contains a Replication Foci Targeting Sequence (RFTS) domain homologous to the RFTS domain of the human DNA methyltransferase DNMT1. We show that the Raf2 RFTS domain is required for centromeric heterochromatin formation as its mutation disrupts H3K9 methylation but not the processing of centromeric transcripts into small interfering RNAs (siRNAs) by the RNAi pathway. Analysis of biochemical interactions demonstrates that the RFTS domain mediates an interaction between Raf2 and the CLRC component Cul4. We conclude that the RFTS domain of Raf2 is a protein interaction module that plays an important role in heterochromatin formation at centromeres.
Collapse
Affiliation(s)
- Sharon A. White
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Alessia Buscaino
- School of Biosciences, Kent Fungal Group, University of Kent, Canterbury, Kent, United Kingdom
| | - Luis Sanchez-Pulido
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Chris P. Ponting
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Matthew W. Nowicki
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, Scotland, United Kingdom
| | - Robin C. Allshire
- Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, Scotland, United Kingdom
- * E-mail:
| |
Collapse
|
41
|
Joh RI, Palmieri CM, Hill IT, Motamedi M. Regulation of histone methylation by noncoding RNAs. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:1385-94. [PMID: 24954181 DOI: 10.1016/j.bbagrm.2014.06.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 05/30/2014] [Accepted: 06/09/2014] [Indexed: 12/19/2022]
Abstract
Cells can adapt to their environment and develop distinct identities by rewiring their transcriptional networks to regulate the output of key biological pathways without concomitant mutations to the underlying genes. These alterations, called epigenetic changes, persist stably through mitotic or, in some instances, meiotic cell divisions. In eukaryotes, heritable changes to chromatin structure are a prominent, but not exclusive, mechanism by which epigenetic changes are mediated. These changes are initiated by sequence-specific events, which trigger a cascade of molecular interactions resulting in feedback mechanisms, alterations in chromatin structure, histone posttranslational modifications (PTMs), and ultimately establishment of distinct transcriptional states. In recent years, advances in next generation sequencing have led to the discovery of several novel classes of noncoding RNAs (ncRNAs). In addition to their well-established cytoplasmic roles in posttranscriptional regulation of gene expression, ncRNAs have emerged as key regulators of epigenetic changes via chromatin-dependent mechanisms in organisms ranging from yeast to man. They function by affecting chromatin structure, histone PTMs, and the recruitment of transcriptional activating or repressing complexes. Among histone PTMs, lysine methylation serves as the binding substrate for the recruitment of key protein complexes involved in the regulation of genome architecture, stability, and gene expression. In this review, we will outline the known mechanisms by which ncRNAs of different origins regulate histone methylation, and in doing so contribute to a variety of genome regulatory functions in eukaryotes.
Collapse
Affiliation(s)
- Richard I Joh
- Massachusetts General Hospital Cancer Center and Department of Medicine, Harvard Medical School,149 13th Street, Charlestown, MA 02129, USA
| | - Christina M Palmieri
- Massachusetts General Hospital Cancer Center and Department of Medicine, Harvard Medical School,149 13th Street, Charlestown, MA 02129, USA
| | - Ian T Hill
- Massachusetts General Hospital Cancer Center and Department of Medicine, Harvard Medical School,149 13th Street, Charlestown, MA 02129, USA; PhD Program in Biological and Biomedical Sciences, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Mo Motamedi
- Massachusetts General Hospital Cancer Center and Department of Medicine, Harvard Medical School,149 13th Street, Charlestown, MA 02129, USA.
| |
Collapse
|
42
|
Shah S, Wittmann S, Kilchert C, Vasiljeva L. lncRNA recruits RNAi and the exosome to dynamically regulate pho1 expression in response to phosphate levels in fission yeast. Genes Dev 2014; 28:231-44. [PMID: 24493644 PMCID: PMC3923966 DOI: 10.1101/gad.230177.113] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Numerous noncoding transcripts of unknown function have recently been identified. In this study, we report a novel mechanism that relies on transcription of noncoding RNA prt (pho1-repressing transcript) regulating expression of the pho1 gene. A product of this gene, Pho1, is a major secreted phosphatase needed for uptake of extracellular phosphate in fission yeast. prt is produced from the promoter located upstream of the pho1 gene in response to phosphate, and its transcription leads to deposition of RNAi-dependent H3K9me2 across the pho1 locus. In contrast, phosphate starvation leads to loss of H3K9me2 and pho1 induction. Strikingly, deletion of Clr4, a H3K9 methyltransferase, results in faster pho1 induction in response to phosphate starvation. We propose a new role for noncoding transcription in establishing transient heterochromatin to mediate an effective transcriptional response to environmental stimuli. RNAi recruitment to prt depends on the RNA-binding protein Mmi1. Importantly, we found that the exosome complex and Mmi1 are required for transcription termination and the subsequent degradation of prt but not pho1 mRNA. Moreover, in mitotic cells, transcription termination of meiotic RNAs also relies on this mechanism. We propose that exosome-dependent termination constitutes a specialized system that primes transcripts for degradation to ensure their efficient elimination.
Collapse
Affiliation(s)
- Sneha Shah
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | | | | | | |
Collapse
|
43
|
Yu R, Jih G, Iglesias N, Moazed D. Determinants of heterochromatic siRNA biogenesis and function. Mol Cell 2013; 53:262-76. [PMID: 24374313 DOI: 10.1016/j.molcel.2013.11.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 10/16/2013] [Accepted: 11/21/2013] [Indexed: 12/13/2022]
Abstract
Endogenous small interfering RNAs (siRNAs) and other classes of small RNA provide the specificity signals for silencing of transposons and repeated DNA elements at the posttranscriptional and transcriptional levels. However, the determinants that define an siRNA-producing region or control the silencing function of siRNAs are poorly understood. Here we show that convergent antisense transcription and availability of the Dicer ribonuclease are the key determinants for primary siRNA generation. Surprisingly, Dicer makes dual contributions to heterochromatin formation, promoting histone H3 lysine 9 methylation independently of its catalytic activity, in addition to its well-known role in catalyzing siRNA generation. Furthermore, sequences in the 3' UTR of an mRNA-coding gene inhibit the ability of siRNAs to promote heterochromatin formation, providing another layer of control that prevents the silencing of protein-coding RNAs. Our results reveal distinct mechanisms that limit siRNA generation to centromeric DNA repeats and prevent spurious siRNA-mediated silencing at euchromatic loci.
Collapse
Affiliation(s)
- Ruby Yu
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Gloria Jih
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Nahid Iglesias
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Danesh Moazed
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
44
|
Marasovic M, Zocco M, Halic M. Argonaute and Triman generate dicer-independent priRNAs and mature siRNAs to initiate heterochromatin formation. Mol Cell 2013; 52:173-83. [PMID: 24095277 DOI: 10.1016/j.molcel.2013.08.046] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 06/27/2013] [Accepted: 08/22/2013] [Indexed: 12/24/2022]
Abstract
RNAi is a conserved mechanism in which small RNAs induce silencing of complementary targets. We have previously identified priRNAs, a class of Dicer-independent small RNAs in fission yeast. The mechanism by which Dicer-independent small RNAs are generated is not well understood in any species. Here we reconstitute the final steps of priRNA and siRNA biogenesis in vitro. We identify the 3'-5' exonuclease Triman and demonstrate that Argonaute, loaded with longer RNA precursors, recruits Triman to generate mature priRNAs and siRNAs. We show that priRNA and siRNA trimming is required for de novo assembly of heterochromatin at centromeric repeats and the mat locus and for maintenance of heterochromatin at developmental genes. Furthermore, in rrp6Δ cells RNAi targets diverse genes in a Triman-dependent way, indicating that the exosome protects the genome from spurious RNAi. Our results suggest that Argonaute association with RNA degradation products generates priRNAs and triggers RNAi in a process of transcriptome surveillance.
Collapse
Affiliation(s)
- Mirela Marasovic
- Gene Center Munich and Department of Biochemistry, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | | | | |
Collapse
|
45
|
Regulation of SirT1-nucleomethylin binding by rRNA coordinates ribosome biogenesis with nutrient availability. Mol Cell Biol 2013; 33:3835-48. [PMID: 23897426 DOI: 10.1128/mcb.00476-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Nucleomethylin (NML), a novel nucleolar protein, is important for mediating the assembly of the energy-dependent nucleolar silencing complex (eNoSC), which also contains SirT1 and SUV39H1. eNoSC represses rRNA transcription during nutrient deprivation, thus reducing energy expenditure and improving cell survival. We found that NML is an RNA binding protein that copurifies with 5S, 5.8S, and 28S rRNA. The SirT1 and RNA binding regions on NML showed partial overlap, and the NML-SirT1 interaction was competitively inhibited by rRNA. Nutrient deprivation triggered downregulation of rRNA transcription, reduced the level of NML-associated rRNA, and stimulated NML-SirT1 binding. Assembly of eNoSC facilitated repression of pre-rRNA transcription. These results suggest that nascent rRNA generates a positive-feedback signal by suppressing the assembly of eNoSC and protecting active ribosomal DNA units from heterochromatin formation. This RNA-mediated mechanism enables the eNoSC to amplify the effects of upstream nutrient-responsive regulators.
Collapse
|
46
|
Alper BJ, Lowe BR, Partridge JF. Centromeric heterochromatin assembly in fission yeast--balancing transcription, RNA interference and chromatin modification. Chromosome Res 2012; 20:521-34. [PMID: 22733402 DOI: 10.1007/s10577-012-9288-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Distinct regions of the eukaryotic genome are packaged into different types of chromatin, with euchromatin representing gene rich, transcriptionally active regions and heterochromatin more condensed and gene poor. The assembly and maintenance of heterochromatin is important for many aspects of genome control, including silencing of gene transcription, suppression of recombination, and to ensure proper chromosome segregation. The precise mechanisms underlying heterochromatin establishment and maintenance are still unclear, but much progress has been made towards understanding this process during the last few years, particularly from studies performed in fission yeast. In this review, we hope to provide a conceptual model of centromeric heterochromatin in fission yeast that integrates our current understanding of the competing forces of transcription, replication, and RNA decay that influence its assembly and propagation.
Collapse
Affiliation(s)
- Benjamin J Alper
- Department of Biochemistry, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | | | | |
Collapse
|
47
|
Abstract
Pericentromeric heterochromatin formation is mediated by repressive histone H3 lysine 9 methylation (H3K9Me) and its recognition by HP1 proteins. Intriguingly, in many organisms, RNAi is coupled to this process through poorly understood mechanisms. In Schizosaccharomyces pombe, the H3-K9 methyltransferase Clr4 and the heterochromatin protein 1 (HP1) ortholog Swi6 are critical for RNAi, whereas RNAi stimulates H3K9Me. In addition to the endoribonuclease Dcr1, RNAi in S. pombe requires two interacting protein complexes, the RITS complex, which contains an Argonaute subunit, and the RDRC complex, which contains an RNA-dependent RNA polymerase subunit. We previously identified Ers1 (essential for RNAi-dependent silencing) as an orphan protein that genetically acts in the RNAi pathway. Using recombinant proteins, we show here that Ers1 directly and specifically interacts with HP1/Swi6. Two-hybrid assays indicate that Ers1 also directly interacts with several RNAi factors. Consistent with these interactions, Ers1 associates in vivo with the RITS complex, the RDRC complex, and Dcr1, and it promotes interactions between these factors. Ers1, like Swi6, is also required for RNAi complexes to associate with pericentromeric noncoding RNAs. Overexpression of Ers1 results in a dominant-negative phenotype that can be specifically suppressed by increasing levels of the RDRC subunit Hrr1 or of Dcr1, further supporting a functional role for Ers1 in promoting the assembly of the RNAi machinery. Through the interactions described here, Ers1 may promote RNAi by tethering the corresponding enzyme complexes to HP1-coated chromatin, thereby placing them in proximity to the nascent noncoding RNA substrate.
Collapse
|
48
|
Holoch D, Moazed D. RNAi in fission yeast finds new targets and new ways of targeting at the nuclear periphery. Genes Dev 2012; 26:741-5. [PMID: 22508721 DOI: 10.1101/gad.191155.112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
RNAi in Schizosaccharomyces pombe is critical for centromeric heterochromatin formation. It has remained unclear, however, whether RNAi also regulates the expression of protein-coding loci. In the April 1, 2012, issue of Genes & Development, Woolcock and colleagues (pp. 683-667) reported an elegant mechanism for the conditional RNAi-mediated repression of stress response genes involving association with Dcr1 at the nuclear pore. Unexpectedly, the initial targeting of RNAi components to these genes does not require small RNA guides.
Collapse
Affiliation(s)
- Daniel Holoch
- Department of Cell Biology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | | |
Collapse
|
49
|
Mmi1 RNA surveillance machinery directs RNAi complex RITS to specific meiotic genes in fission yeast. EMBO J 2012; 31:2296-308. [PMID: 22522705 DOI: 10.1038/emboj.2012.105] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 03/29/2012] [Indexed: 12/24/2022] Open
Abstract
RNA interference (RNAi) silences gene expression by acting both at the transcriptional and post-transcriptional levels in a broad range of eukaryotes. In the fission yeast Schizosaccharomyces pombe the RNA-Induced Transcriptional Silencing (RITS) RNAi complex mediates heterochromatin formation at non-coding and repetitive DNA. However, the targeting and role of RITS at other genomic regions, including protein-coding genes, remain unknown. Here we show that RITS localizes to specific meiotic genes and mRNAs. Remarkably, RITS is guided to these meiotic targets by the RNA-binding protein Mmi1 and its associated RNA surveillance machinery that together degrade selective meiotic mRNAs during vegetative growth. Upon sexual differentiation, RITS localization to the meiotic genes and mRNAs is lost. Large-scale identification of Mmi1 RNA targets reveals that RITS subunit Chp1 associates with the vast majority of them. In addition, loss of RNAi affects the effective repression of sexual differentiation mediated by the Mmi1 RNA surveillance machinery. These findings uncover a new mechanism for recruiting RNAi to specific meiotic genes and suggest that RNAi participates in the control of sexual differentiation in fission yeast.
Collapse
|
50
|
Heterochromatin protein 1 homologue Swi6 acts in concert with Ers1 to regulate RNAi-directed heterochromatin assembly. Proc Natl Acad Sci U S A 2012; 109:6159-64. [PMID: 22474355 DOI: 10.1073/pnas.1116972109] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In fission yeast, the RNAi pathway is required for centromeric heterochromatin assembly. siRNAs derived from centromeric transcripts are incorporated into the RNA-induced transcriptional silencing (RITS) complex and direct it to nascent homologous transcripts. The RNA-induced transcriptional silencing-bound nascent transcripts further recruit the RNA-directed RNA polymerase complex (RDRC) to promote dsRNA synthesis and siRNA production. Heterochromatin coated with Swi6/Heterochromain Protein 1 is then formed following recruitment of chromatin modification machinery. Swi6 is also required for the upstream production of siRNA, although the mechanism for this has remained obscure. Here, we demonstrate that Swi6 recruits RDRC to heterochromatin through Ers1, an RNAi factor intermediate. An ers1(+) mutant allele (ers1-C62) was identified in a genetic screen for mutants that alleviate centromeric silencing, and this phenotype was suppressed by overexpression of either the Hrr1 RDRC subunit or Clr4 histone H3-K9 methyltransferase. Ers1 physically interacts with Hrr1, and loss of Ers1 impairs RDRC centromeric localization. Although Ers1 failed to bind Clr4, a direct interaction with Swi6 was detected, and centromeric localization of Swi6 was enhanced by Clr4 overexpression in ers1-C62 cells. Consistent with this, deletion of swi6(+) reduced centromeric localization of Ers1 and RDRC. Moreover, tethering of Ers1 or Hrr1 to centromeric heterochromatin partially bypassed Swi6 function. These findings demonstrate an alternative mechanism for RDRC recruitment and explain the essential role of Swi6/Heterochromain Protein 1 in RNAi-directed heterochromatin assembly.
Collapse
|