1
|
Donnio LM, Giglia-Mari G. Keep calm and reboot - how cells restart transcription after DNA damage and DNA repair. FEBS Lett 2024. [PMID: 38991979 DOI: 10.1002/1873-3468.14964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 04/12/2024] [Accepted: 04/21/2024] [Indexed: 07/13/2024]
Abstract
The effects of genotoxic agents on DNA and the processes involved in their removal have been thoroughly studied; however, very little is known about the mechanisms governing the reinstatement of cellular activities after DNA repair, despite restoration of the damage-induced block of transcription being essential for cell survival. In addition to impeding transcription, DNA lesions have the potential to disrupt the precise positioning of chromatin domains within the nucleus and alter the meticulously organized architecture of the nucleolus. Alongside the necessity of resuming transcription mediated by RNA polymerase 1 and 2 transcription, it is crucial to restore the structure of the nucleolus to facilitate optimal ribosome biogenesis and ensure efficient and error-free translation. Here, we examine the current understanding of how transcriptional activity from RNA polymerase 2 is reinstated following DNA repair completion and explore the mechanisms involved in reassembling the nucleolus to safeguard the correct progression of cellular functions. Given the lack of information on this vital function, this Review seeks to inspire researchers to explore deeper into this specific subject and offers essential suggestions on how to investigate this complex and nearly unexplored process further.
Collapse
Affiliation(s)
- Lise-Marie Donnio
- Institut NeuroMyoGène-Pathophysiology and Genetics of Neuron and Muscle (INMG_PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, Lyon, 69008, France
| | - Giuseppina Giglia-Mari
- Institut NeuroMyoGène-Pathophysiology and Genetics of Neuron and Muscle (INMG_PGNM), CNRS UMR 5261, INSERM U1315, Université Claude Bernard Lyon 1, Lyon, 69008, France
| |
Collapse
|
2
|
Miura H, Nakamura A, Kurosaki A, Kotani A, Motojima M, Tanaka K, Kakuta S, Ogiwara S, Ohmi Y, Komaba H, Schilit SLP, Morton CC, Gurumurthy CB, Ohtsuka M. Targeted insertion of conditional expression cassettes into the mouse genome using the modified i-PITT. BMC Genomics 2024; 25:568. [PMID: 38840068 PMCID: PMC11155135 DOI: 10.1186/s12864-024-10250-0] [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: 08/05/2023] [Accepted: 03/22/2024] [Indexed: 06/07/2024] Open
Abstract
BACKGROUND Transgenic (Tg) mice are widely used in biomedical research, and they are typically generated by injecting transgenic DNA cassettes into pronuclei of one-cell stage zygotes. Such animals often show unreliable expression of the transgenic DNA, one of the major reasons for which is random insertion of the transgenes. We previously developed a method called "pronuclear injection-based targeted transgenesis" (PITT), in which DNA constructs are directed to insert at pre-designated genomic loci. PITT was achieved by pre-installing so called landing pad sequences (such as heterotypic LoxP sites or attP sites) to create seed mice and then injecting Cre recombinase or PhiC31 integrase mRNAs along with a compatible donor plasmid into zygotes derived from the seed mice. PITT and its subsequent version, improved PITT (i-PITT), overcome disadvantages of conventional Tg mice such as lack of consistent and reliable expression of the cassettes among different Tg mouse lines, and the PITT approach is superior in terms of cost and labor. One of the limitations of PITT, particularly using Cre-mRNA, is that the approach cannot be used for insertion of conditional expression cassettes using Cre-LoxP site-specific recombination. This is because the LoxP sites in the donor plasmids intended for achieving conditional expression of the transgene will interfere with the PITT recombination reaction with LoxP sites in the landing pad. RESULTS To enable the i-PITT method to insert a conditional expression cassette, we modified the approach by simultaneously using PhiC31o and FLPo mRNAs. We demonstrate the strategy by creating a model containing a conditional expression cassette at the Rosa26 locus with an efficiency of 13.7%. We also demonstrate that inclusion of FLPo mRNA excludes the insertion of vector backbones in the founder mice. CONCLUSIONS Simultaneous use of PhiC31 and FLP in i-PITT approach allows insertion of donor plasmids containing Cre-loxP-based conditional expression cassettes.
Collapse
Affiliation(s)
- Hiromi Miura
- Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Kanagawa, Japan
| | - Ayaka Nakamura
- Life Science Support Center, Tokai University, Kanagawa, Japan
| | - Aki Kurosaki
- Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Kanagawa, Japan
| | - Ai Kotani
- The Institute of Medical Sciences, Tokai University, Kanagawa, Japan
- Department of Innovative Medical Science, Tokai University School of Medicine, Kanagawa, Japan
- Division of Hematological Malignancy, Institute of Medical Sciences, Tokai University, Kanagawa, Japan
| | - Masaru Motojima
- Department of Clinical Pharmacology, Tokai University School of Medicine, Kanagawa, Japan
| | - Keiko Tanaka
- Departments of Basic Medicine, Tokai University School of Medicine, Kanagawa, Japan
- Division of Kidney, Diabetes and Endocrine Diseases, Okayama University Hospital, Okayama, Japan
| | - Shigeru Kakuta
- Laboratory of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology (CRIIM), The University of Tokyo, Tokyo, Japan
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Sanae Ogiwara
- Life Science Support Center, Tokai University, Kanagawa, Japan
| | - Yuhsuke Ohmi
- Department of Clinical Engineering, Chubu University College of Life and Health Sciences, Kasugai, Aichi, Japan
| | - Hirotaka Komaba
- The Institute of Medical Sciences, Tokai University, Kanagawa, Japan
- Division of Nephrology, Endocrinology and Metabolism, Tokai University School of Medicine, Kanagawa, Japan
| | - Samantha L P Schilit
- Program in Genetics and Genomics and Certificate Program in Leder Human Biology and Translational Medicine, Biological and Biomedical Sciences Program, Graduate School of Arts and Sciences, Harvard University, Cambridge, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Cynthia C Morton
- Departments of Obstetrics and Gynecology and of Pathology, Brigham and Women's Hospital, Boston, MA, USA
- Institute Member, Broad Institute of Massachusetts Institute of Technology and Harvard University, Kendall Square, Cambridge, MA, USA
- Manchester Center for Hearing and Deafness, University of Manchester, Manchester, UK
| | - Channabasavaiah B Gurumurthy
- Mouse Genome Engineering Core Facility, University of Nebraska Medical Center, Omaha, NE, USA
- Department of Genetics, Cell Biology and Anatomy, College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Masato Ohtsuka
- Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine, Kanagawa, Japan.
- The Institute of Medical Sciences, Tokai University, Kanagawa, Japan.
| |
Collapse
|
3
|
Ames A, Seman M, Larkin A, Raiymbek G, Chen Z, Levashkevich A, Kim B, Biteen JS, Ragunathan K. Epigenetic memory is governed by an effector recruitment specificity toggle in Heterochromatin Protein 1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.28.569027. [PMID: 38077059 PMCID: PMC10705379 DOI: 10.1101/2023.11.28.569027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
HP1 proteins are essential for establishing and maintaining transcriptionally silent heterochromatin. They dimerize, forming a binding interface to recruit diverse chromatin-associated factors. HP1 proteins are specialized and rapidly evolve, but the extent of variation required to achieve functional specialization is unknown. To investigate how changes in amino acid sequence impacts epigenetic inheritance, we performed a targeted mutagenesis screen of the S. pombe HP1 homolog, Swi6. Substitutions within an auxiliary surface adjacent to the HP1 dimerization interface produced Swi6 variants with divergent maintenance properties. Remarkably, substitutions at a single amino acid position led to the persistent gain or loss of epigenetic inheritance. These substitutions increased Swi6 chromatin occupancy in vivo and altered Swi6-protein interactions that reprogram H3K9me maintenance. We show that relatively minor changes in Swi6 amino acid composition can lead to profound changes in epigenetic inheritance which provides a redundant mechanism to evolve novel effector specificity. .
Collapse
|
4
|
Li T, Petreaca RC, Forsburg SL. Chromodomain mutation in S. pombe Kat5/Mst1 affects centromere dynamics and DNA repair. PLoS One 2024; 19:e0300732. [PMID: 38662722 PMCID: PMC11045136 DOI: 10.1371/journal.pone.0300732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 03/04/2024] [Indexed: 04/28/2024] Open
Abstract
KAT5 (S. pombe Mst1, human TIP60) is a MYST family histone acetyltransferase conserved from yeast to humans that is involved in multiple cellular activities. This family is characterized in part by containing a chromodomain, a motif associated with binding methylated histones. We show that a chromodomain mutation in the S. pombe Kat5, mst1-W66R, has defects in pericentromere silencing. mst1-W66R is sensitive to camptothecin (CPT) but only at an increased temperature of 36°C, although it is proficient for growth at this temperature. We also describe a de-silencing effect at the pericentromere by CPT that is independent of RNAi and methylation machinery. We also show that mst1-W66R disrupts recruitment of proteins to repair foci in response to camptothecin-induced DNA damage. Our data suggest a function of Mst1 chromodomain in centromere heterochromatin formation and a separate role in genome-wide damage repair in CPT.
Collapse
Affiliation(s)
- Tingting Li
- Program in Molecular & Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States of America
| | - Ruben C. Petreaca
- Program in Molecular & Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States of America
| | - Susan L. Forsburg
- Program in Molecular & Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States of America
| |
Collapse
|
5
|
Seman M, Levashkevich A, Larkin A, Huang F, Ragunathan K. Uncoupling the distinct functions of HP1 proteins during heterochromatin establishment and maintenance. Cell Rep 2023; 42:113428. [PMID: 37952152 DOI: 10.1016/j.celrep.2023.113428] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 09/28/2023] [Accepted: 10/26/2023] [Indexed: 11/14/2023] Open
Abstract
H3K9 methylation (H3K9me) marks transcriptionally silent genomic regions called heterochromatin. HP1 proteins are required to establish and maintain heterochromatin. HP1 proteins bind to H3K9me, recruit factors that promote heterochromatin formation, and oligomerize to form phase-separated condensates. We do not understand how these different HP1 properties are involved in establishing and maintaining transcriptional silencing. Here, we demonstrate that the S. pombe HP1 homolog, Swi6, can be completely bypassed to establish silencing at ectopic and endogenous loci when an H3K4 methyltransferase, Set1, and an H3K14 acetyltransferase, Mst2, are deleted. Deleting Set1 and Mst2 enhances Clr4 enzymatic activity, leading to higher H3K9me levels and spreading. In contrast, Swi6 and its capacity to oligomerize were indispensable during epigenetic maintenance. Our results demonstrate the role of HP1 proteins in regulating histone modification crosstalk during establishment and identify a genetically separable function in maintaining epigenetic memory.
Collapse
Affiliation(s)
- Melissa Seman
- Department of Biology, Brandeis University, Waltham, MA 02451, USA
| | | | - Ajay Larkin
- Department of Biology, Brandeis University, Waltham, MA 02451, USA
| | - Fengting Huang
- Department of Biology, Brandeis University, Waltham, MA 02451, USA
| | | |
Collapse
|
6
|
Seman M, Levashkevich A, Larkin A, Huang F, Ragunathan K. Uncoupling the distinct functions of HP1 proteins during heterochromatin establishment and maintenance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.30.538869. [PMID: 37961629 PMCID: PMC10634687 DOI: 10.1101/2023.04.30.538869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
H3K9 methylation (H3K9me) marks transcriptionally silent genomic regions called heterochromatin. HP1 proteins are required to establish and maintain heterochromatin. HP1 proteins bind to H3K9me, recruit factors that promote heterochromatin formation, and oligomerize to form phase-separated condensates. We do not understand how HP1 protein binding to heterochromatin establishes and maintains transcriptional silencing. Here, we demonstrate that the S.pombe HP1 homolog, Swi6, can be completely bypassed to establish silencing at ectopic and endogenous loci when an H3K4 methyltransferase, Set1 and an H3K14 acetyltransferase, Mst2 are deleted. Deleting Set1 and Mst2 enhances Clr4 enzymatic activity, leading to higher H3K9me levels and spreading. In contrast, Swi6 and its capacity to oligomerize were indispensable during epigenetic maintenance. Our results demonstrate the role of HP1 proteins in regulating histone modification crosstalk during establishment and identifies a genetically separable function in maintaining epigenetic memory.
Collapse
Affiliation(s)
- Melissa Seman
- Department of Biology, Brandeis University, Waltham, MA 02451 USA
| | | | - Ajay Larkin
- Department of Biology, Brandeis University, Waltham, MA 02451 USA
| | - Fengting Huang
- Department of Biology, Brandeis University, Waltham, MA 02451 USA
| | - Kaushik Ragunathan
- Department of Biology, Brandeis University, Waltham, MA 02451 USA
- Lead Contact
| |
Collapse
|
7
|
Brickner JH. Inheritance of epigenetic transcriptional memory through read-write replication of a histone modification. Ann N Y Acad Sci 2023; 1526:50-58. [PMID: 37391188 PMCID: PMC11216120 DOI: 10.1111/nyas.15033] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2023]
Abstract
Epigenetic transcriptional regulation frequently requires histone modifications. Some, but not all, of these modifications are able to template their own inheritance. Here, I discuss the molecular mechanisms by which histone modifications can be inherited and relate these ideas to new results about epigenetic transcriptional memory, a phenomenon that poises recently repressed genes for faster reactivation and has been observed in diverse organisms. Recently, we found that the histone H3 lysine 4 dimethylation that is associated with this phenomenon plays a critical role in sustaining memory and, when factors critical for the establishment of memory are inactivated, can be stably maintained through multiple mitoses. This chromatin-mediated inheritance mechanism may involve a physical interaction between an H3K4me2 reader, SET3C, and an H3K4me2 writer, Spp1- COMPASS. This is the first example of a chromatin-mediated inheritance of a mark that promotes transcription.
Collapse
Affiliation(s)
- Jason H Brickner
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, USA
| |
Collapse
|
8
|
Li H, Luo J, Zhang W, Hua L, Li K, Wang J, Xu B, Yang C, Wang G, Rouse MN, Dubcovsky J, Chen S. High-resolution mapping of SrTm4, a recessive resistance gene to wheat stem rust. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2023; 136:120. [PMID: 37103626 PMCID: PMC10140103 DOI: 10.1007/s00122-023-04369-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 04/17/2023] [Indexed: 05/13/2023]
Abstract
KEY MESSAGE The diploid wheat recessive stem rust resistance gene SrTm4 was fine-mapped to a 754-kb region on chromosome arm 2AmL and potential candidate genes were identified. Race Ug99 of Puccinia graminis f. sp. tritici (Pgt), the causal agent of wheat stem (or black) rust is one of the most serious threats to global wheat production. The identification, mapping, and deployment of effective stem rust resistance (Sr) genes are critical to reduce this threat. In this study, we generated SrTm4 monogenic lines and found that this gene confers resistance to North American and Chinese Pgt races. Using a large mapping population (9522 gametes), we mapped SrTm4 within a 0.06 cM interval flanked by marker loci CS4211 and 130K1519, which corresponds to a 1.0-Mb region in the Chinese Spring reference genome v2.1. A physical map of the SrTm4 region was constructed with 11 overlapping BACs from the resistant Triticum monococcum PI 306540. Comparison of the 754-kb physical map with the genomic sequence of Chinese Spring and a discontinuous BAC sequence of DV92 revealed a 593-kb chromosomal inversion in PI 306540. Within the candidate region, we identified an L-type lectin-domain containing receptor kinase (LLK1), which was disrupted by the proximal inversion breakpoint, as a potential candidate gene. Two diagnostic dominant markers were developed to detect the inversion breakpoints. In a survey of T. monococcum accessions, we identified 10 domesticated T. monococcum subsp. monococcum genotypes, mainly from the Balkans, carrying the inversion and showing similar mesothetic resistant infection types against Pgt races. The high-density map and tightly linked molecular markers developed in this study are useful tools to accelerate the deployment of SrTm4-mediated resistance in wheat breeding programs.
Collapse
Affiliation(s)
- Hongna Li
- National Key Laboratory of Wheat Improvement, Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, 261325, Shandong, China
| | - Jing Luo
- National Key Laboratory of Wheat Improvement, Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, 261325, Shandong, China
| | - Wenjun Zhang
- Department of Plant Sciences, University of California, Davis, CA95616, USA
| | - Lei Hua
- National Key Laboratory of Wheat Improvement, Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, 261325, Shandong, China
| | - Kun Li
- Department of Plant Sciences, University of California, Davis, CA95616, USA
| | - Jian Wang
- National Key Laboratory of Wheat Improvement, Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, 261325, Shandong, China
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, China
| | - Binyang Xu
- National Key Laboratory of Wheat Improvement, Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, 261325, Shandong, China
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, China
| | - Chen Yang
- National Key Laboratory of Wheat Improvement, Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, 261325, Shandong, China
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, China
| | - Guiping Wang
- National Key Laboratory of Wheat Improvement, Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, 261325, Shandong, China
| | - Matthew N Rouse
- US Department of Agriculture-Agricultural Research Service, Cereal Disease Laboratory and Department of Plant Pathology, University of Minnesota, St. Paul, MN, 55108, USA.
| | - Jorge Dubcovsky
- Department of Plant Sciences, University of California, Davis, CA95616, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD, 20815, USA.
| | - Shisheng Chen
- National Key Laboratory of Wheat Improvement, Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, 261325, Shandong, China.
| |
Collapse
|
9
|
Differential Paralog-Specific Expression of Multiple Small Subunit Proteins Cause Variations in Rpl42/eL42 Incorporation in Ribosome in Fission Yeast. Cells 2022; 11:cells11152381. [PMID: 35954225 PMCID: PMC9367792 DOI: 10.3390/cells11152381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/26/2022] [Accepted: 07/29/2022] [Indexed: 11/16/2022] Open
Abstract
Ribosomes within a cell are commonly viewed as biochemically homogenous RNA–protein super-complexes performing identical functions of protein synthesis. However, recent evidence suggests that ribosomes may be a more dynamic macromolecular complex with specialized roles. Here, we present extensive genetic and molecular evidence in the fission yeast S. pombe that the paralogous genes for many ribosomal proteins (RPs) are functionally different, despite that they encode the same ribosomal component, often with only subtle differences in the sequences. Focusing on the rps8 paralog gene deletions rps801d and rps802d, we showed that the mutant cells differ in the level of Rpl42p in actively translating ribosomes and that their phenotypic differences reside in the Rpl42p level variation instead of the subtle protein sequence difference between Rps801p and Rps802p. Additional 40S ribosomal protein paralog pairs also exhibit similar phenotypic differences via differential Rpl42p levels in actively translating ribosomes. Together, our work identifies variations in the Rpl42p level as a potential form of ribosome heterogeneity in biochemical compositions and suggests a possible connection between large and small subunits during ribosome biogenesis that may cause such heterogeneity. Additionally, it illustrates the complexity of the underlying mechanisms for the genetic specificity of ribosome paralogs.
Collapse
|
10
|
A stress-blinded Atf1 can fully assemble heterochromatin in a RNAi-independent minimal mat locus but impairs directionality of mat2/3 switching. iScience 2022; 25:104820. [PMID: 35992058 PMCID: PMC9389250 DOI: 10.1016/j.isci.2022.104820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 06/03/2022] [Accepted: 07/19/2022] [Indexed: 11/28/2022] Open
Abstract
The MAP kinase Sty1 phosphorylates and activates the transcription factor Atf1 in response to several stress conditions, which then shifts from a transcriptional repressor to an activator. Atf1 also participates in heterochromatin assembly at the mat locus, in combination with the RNA interference (RNAi) machinery. Here, we study the role of signal-dependent phosphorylation of Atf1 in heterochromatin establishment at mat, using different Atf1 phospho mutants. Although a hypo-phosphorylation Atf1 mutant, Atf1.10M, mediates heterochromatin assembly, the phosphomimic Atf1.10D is unable to maintain silencing. In a minimal mat locus, lacking the RNAi-recruiting cis elements and displaying intermediate silencing, Atf1.10M restores full heterochromatin and silencing. However, evolution experiments with this stress-blinded Atf1.10M show that it is unable to facilitate switching between the donor site mat3 and mat1. We propose that the unphosphorylated, inactive Atf1 contributes to proper heterochromatin assembly by recruiting repressive complexes, but its stress-dependent phosphorylation is required for recombination/switching to occur. The phosphorylation domain of Atf1 TF is required for heterochromatin assembly at mat Hypo-phosphorylated Atf1.10M mediates silencing by recruiting repressive complexes Stress-dependent phosphorylation of Atf1 is required for recombination and switching Atf1.10M is a heterochromatin assembly factor but impairs mat2/3 switching
Collapse
|
11
|
Ohzeki J, Kugou K, Otake K, Okazaki K, Takahashi S, Shibata D, Masumoto H. Introduction of a long synthetic repetitive DNA sequence into cultured tobacco cells. PLANT BIOTECHNOLOGY (TOKYO, JAPAN) 2022; 39:101-110. [PMID: 35937535 PMCID: PMC9300429 DOI: 10.5511/plantbiotechnology.21.1210a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 12/10/2021] [Indexed: 05/15/2023]
Abstract
Genome information has been accumulated for many species, and these genes and regulatory sequences are expected to be applied in plants by enhancing or creating new metabolic pathways. We hypothesized that manipulating a long array of repetitive sequences using tethered chromatin modulators would be effective for robust regulation of gene expression in close proximity to the arrays. This approach is based on a human artificial chromosome made of long synthetic repetitive DNA sequences in which we manipulated the chromatin by tethering the modifiers. However, a method for introducing long repetitive DNA sequences into plants has not yet been established. Therefore, we constructed a bacterial artificial chromosome-based binary vector in Escherichia coli cells to generate a construct in which a cassette of marker genes was inserted into 60-kb synthetic human centromeric repetitive DNA. The binary vector was then transferred to Agrobacterium cells and its stable maintenance confirmed. Next, using Agrobacterium-mediated genetic transformation, this construct was successfully introduced into the genome of cultured tobacco BY-2 cells to obtain a large number of stable one-copy strains. ChIP analysis of obtained BY-2 cell lines revealed that the introduced synthetic repetitive DNA has moderate chromatin modification levels with lower heterochromatin (H3K9me2) or euchromatin (H3K4me3) modifications compared to the host centromeric repetitive DNA or an active Tub6 gene, respectively. Such a synthetic DNA sequence with moderate chromatin modification levels is expected to facilitate manipulation of the chromatin structure to either open or closed.
Collapse
Affiliation(s)
- Junichirou Ohzeki
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan
| | - Kazuto Kugou
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan
| | - Koichiro Otake
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan
| | - Koei Okazaki
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan
| | - Seiji Takahashi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8579, Japan
| | - Daisuke Shibata
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan
| | - Hiroshi Masumoto
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, Kisarazu, Chiba 292-0818, Japan
- E-mail: Tel: +81-438-52-3952 Fax: +81-438-52-3946
| |
Collapse
|
12
|
Boldyreva LV, Andreyeva EN, Pindyurin AV. Position Effect Variegation: Role of the Local Chromatin Context in Gene Expression Regulation. Mol Biol 2022. [DOI: 10.1134/s0026893322030049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
13
|
Kianfard Z, Cheung K, Sabatinos SA. Cell Cycle Synchrony Methods for Fission Yeast, Schizosaccharomyces pombe. Methods Mol Biol 2022; 2579:169-179. [PMID: 36045206 DOI: 10.1007/978-1-0716-2736-5_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The fission yeast, Schizosaccharomyces pombe, is a genetically tractable model organism for cell cycle and molecular genetics research. We describe methods to synchronize S. pombe cultures, and the benefits and limitations of each. Drug-induced synchrony is a convenient method to arrest the cell cycle. An example of the drug hydroxyurea is shown, which arrests cells in S-phase. Environmental modulation through media composition or growth conditions may also be used to synchronize cultures, most commonly with nitrogen depletion to arrest in G1-phase. Finally, examples of temperature-sensitive conditional alleles are shown which arrest the cell cycle at key transition points. Each of these methods must be assessed relative to the desired effect and the process being studied, providing the best synchrony with the fewest off-target effects.
Collapse
Affiliation(s)
- Zohreh Kianfard
- Molecular Science Program, Yeates School of Graduate Studies, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada
| | - Kyle Cheung
- Molecular Science Program, Yeates School of Graduate Studies, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada
| | - Sarah A Sabatinos
- Molecular Science Program, Yeates School of Graduate Studies, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada.
- Department of Chemistry and Biology, Toronto Metropolitan University (formerly Ryerson University), Toronto, ON, Canada.
| |
Collapse
|
14
|
Fei Y, Pyott DE, Molnar A. Temperature modulates virus-induced transcriptional gene silencing via secondary small RNAs. THE NEW PHYTOLOGIST 2021; 232:356-371. [PMID: 34185326 DOI: 10.1111/nph.17586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 06/17/2021] [Indexed: 05/08/2023]
Abstract
Virus-induced gene silencing (VIGS) can be harnessed to sequence-specifically degrade host transcripts and induce heritable epigenetic modifications referred to as virus-induced post-transcriptional gene silencing (ViPTGS) and virus-induced transcriptional gene silencing (ViTGS), respectively. Both ViPTGS and ViTGS enable manipulation of endogenous gene expression without the need for transgenesis. Although VIGS has been widely used in many plant species, it is not always uniform or highly efficient. The efficiency of VIGS is affected by developmental, physiological and environmental factors. Here, we use recombinant Tobacco rattle viruses (TRV) to study the effect of temperature on ViPTGS and ViTGS using GFP as a reporter gene of silencing in N. benthamiana 16c plants. We found that unlike ViPTGS, ViTGS was impaired at high temperature. Using a novel mismatch-small interfering RNA (siRNA) tool, which precisely distinguishes virus-derived (primary) from target-generated (secondary) siRNAs, we demonstrated that the lack of secondary siRNA production/amplification was responsible for inefficient ViTGS at 29°C. Moreover, inefficient ViTGS at 29°C inhibited the transmission of epigenetic gene silencing to the subsequent generations. Our finding contributes to understanding the impact of environmental conditions on primary and secondary siRNA production and may pave the way to design/optimize ViTGS for transgene-free crop improvement.
Collapse
Affiliation(s)
- Yue Fei
- Institute of Molecular Plant Sciences, University of Edinburgh, Max Born Crescent, Edinburgh, EH9 3BF, UK
| | - Douglas E Pyott
- Institute of Molecular Plant Sciences, University of Edinburgh, Max Born Crescent, Edinburgh, EH9 3BF, UK
| | - Attila Molnar
- Institute of Molecular Plant Sciences, University of Edinburgh, Max Born Crescent, Edinburgh, EH9 3BF, UK
| |
Collapse
|
15
|
Sperschneider J, Jones AW, Nasim J, Xu B, Jacques S, Zhong C, Upadhyaya NM, Mago R, Hu Y, Figueroa M, Singh KB, Stone EA, Schwessinger B, Wang MB, Taylor JM, Dodds PN. The stem rust fungus Puccinia graminis f. sp. tritici induces centromeric small RNAs during late infection that are associated with genome-wide DNA methylation. BMC Biol 2021; 19:203. [PMID: 34526021 PMCID: PMC8444563 DOI: 10.1186/s12915-021-01123-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 08/13/2021] [Indexed: 02/07/2023] Open
Abstract
Background Silencing of transposable elements (TEs) is essential for maintaining genome stability. Plants use small RNAs (sRNAs) to direct DNA methylation to TEs (RNA-directed DNA methylation; RdDM). Similar mechanisms of epigenetic silencing in the fungal kingdom have remained elusive. Results We use sRNA sequencing and methylation data to gain insight into epigenetics in the dikaryotic fungus Puccinia graminis f. sp. tritici (Pgt), which causes the devastating stem rust disease on wheat. We use Hi-C data to define the Pgt centromeres and show that they are repeat-rich regions (~250 kb) that are highly diverse in sequence between haplotypes and, like in plants, are enriched for young TEs. DNA cytosine methylation is particularly active at centromeres but also associated with genome-wide control of young TE insertions. Strikingly, over 90% of Pgt sRNAs and several RNAi genes are differentially expressed during infection. Pgt induces waves of functionally diversified sRNAs during infection. The early wave sRNAs are predominantly 21 nts with a 5′ uracil derived from genes. In contrast, the late wave sRNAs are mainly 22-nt sRNAs with a 5′ adenine and are strongly induced from centromeric regions. TEs that overlap with late wave sRNAs are more likely to be methylated, both inside and outside the centromeres, and methylated TEs exhibit a silencing effect on nearby genes. Conclusions We conclude that rust fungi use an epigenetic silencing pathway that might have similarity with RdDM in plants. The Pgt RNAi machinery and sRNAs are under tight temporal control throughout infection and might ensure genome stability during sporulation. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01123-z.
Collapse
Affiliation(s)
- Jana Sperschneider
- Biological Data Science Institute, The Australian National University, Canberra, Australia. .,Black Mountain Science and Innovation Park, CSIRO Agriculture and Food, Canberra, Australia.
| | - Ashley W Jones
- Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - Jamila Nasim
- Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - Bo Xu
- Thermo Fisher Scientific, 5 Caribbean Drive, Scoresby, Australia
| | - Silke Jacques
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, Australia
| | - Chengcheng Zhong
- Black Mountain Science and Innovation Park, CSIRO Agriculture and Food, Canberra, Australia
| | - Narayana M Upadhyaya
- Black Mountain Science and Innovation Park, CSIRO Agriculture and Food, Canberra, Australia
| | - Rohit Mago
- Black Mountain Science and Innovation Park, CSIRO Agriculture and Food, Canberra, Australia
| | - Yiheng Hu
- Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - Melania Figueroa
- Black Mountain Science and Innovation Park, CSIRO Agriculture and Food, Canberra, Australia
| | - Karam B Singh
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, Australia.,Centre for Environment and Life Sciences, CSIRO Agriculture and Food, Perth, Australia
| | - Eric A Stone
- Biological Data Science Institute, The Australian National University, Canberra, Australia
| | - Benjamin Schwessinger
- Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - Ming-Bo Wang
- Black Mountain Science and Innovation Park, CSIRO Agriculture and Food, Canberra, Australia
| | - Jennifer M Taylor
- Black Mountain Science and Innovation Park, CSIRO Agriculture and Food, Canberra, Australia
| | - Peter N Dodds
- Black Mountain Science and Innovation Park, CSIRO Agriculture and Food, Canberra, Australia.
| |
Collapse
|
16
|
Schotanus K, Yadav V, Heitman J. Epigenetic dynamics of centromeres and neocentromeres in Cryptococcus deuterogattii. PLoS Genet 2021; 17:e1009743. [PMID: 34464380 PMCID: PMC8407549 DOI: 10.1371/journal.pgen.1009743] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 07/26/2021] [Indexed: 11/25/2022] Open
Abstract
Deletion of native centromeres in the human fungal pathogen Cryptococcus deuterogattii leads to neocentromere formation. Native centromeres span truncated transposable elements, while neocentromeres do not and instead span actively expressed genes. To explore the epigenetic organization of neocentromeres, we analyzed the distribution of the heterochromatic histone modification H3K9me2, 5mC DNA methylation and the euchromatin mark H3K4me2. Native centromeres are enriched for both H3K9me2 and 5mC DNA methylation marks and are devoid of H3K4me2, while neocentromeres do not exhibit any of these features. Neocentromeres in cen10Δ mutants are unstable and chromosome-chromosome fusions occur. After chromosome fusion, the neocentromere is inactivated and the native centromere of the chromosome fusion partner remains as the sole, active centromere. In the present study, the active centromere of a fused chromosome was deleted to investigate if epigenetic memory promoted the re-activation of the inactive neocentromere. Our results show that the inactive neocentromere is not re-activated and instead a novel neocentromere forms directly adjacent to the deleted centromere of the fused chromosome. To study the impact of transcription on centromere stability, the actively expressed URA5 gene was introduced into the CENP-A bound regions of a native centromere. The introduction of the URA5 gene led to a loss of CENP-A from the native centromere, and a neocentromere formed adjacent to the native centromere location. Remarkably, the inactive, native centromere remained enriched for heterochromatin, yet the integrated gene was expressed and devoid of H3K9me2. A cumulative analysis of multiple CENP-A distribution profiles revealed centromere drift in C. deuterogattii, a previously unreported phenomenon in fungi. The CENP-A-binding shifted within the ORF-free regions and showed a possible association with a truncated transposable element. Taken together, our findings reveal that neocentromeres in C. deuterogattii are highly unstable and are not marked with an epigenetic memory, distinguishing them from native centromeres. Linear eukaryotic chromosomes require a specific chromosomal region, the centromere, where the macromolecular kinetochore protein complex assembles. In most organisms, centromeres are located in gene-free, repeat-rich chromosomal regions and may or may not be associated with heterochromatic epigenetic marks. We report that the native centromeres of the human fungal pathogen Cryptococcus deuterogattii are enriched with heterochromatin marks. Deleting a centromere in C. deuterogattii results in formation of neocentromeres that span genes. In some cases, neocentromeres are unstable leading to chromosome-chromosome fusions and neocentromere inactivation. These neocentromeres, unlike native centromeres, lack any of the tested heterochromatic marks or any epigenetic memory. We also found that neocentromere formation can be triggered not only by deletion of the native centromere but also by disrupting its function via insertion of a gene. These results show that neocentromere dynamics in this fungal pathogen are unique among organisms studied so far. Our results also revealed key differences between epigenetics of native centromeres between C. deuterogattii and its sister species, C. neoformans. These finding provide an opportunity to test and study the evolution of centromeres, as well as neocentromeres, in this species complex and how it might contribute to their genome evolution.
Collapse
Affiliation(s)
- Klaas Schotanus
- Duke University Medical Center, Durham, North Carolina, United States of America
| | - Vikas Yadav
- Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joseph Heitman
- Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
17
|
Hou H, Kyriacou E, Thadani R, Klutstein M, Chapman JH, Cooper JP. Centromeres are dismantled by foundational meiotic proteins Spo11 and Rec8. Nature 2021; 591:671-676. [PMID: 33658710 PMCID: PMC8843027 DOI: 10.1038/s41586-021-03279-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 01/22/2021] [Indexed: 01/31/2023]
Abstract
Meiotic processes are potentially dangerous to genome stability and could be disastrous if activated in proliferative cells. Here we show that two key meiosis-defining proteins, the topoisomerase Spo11 (which forms double-strand breaks) and the meiotic cohesin Rec8, can dismantle centromeres. This dismantlement is normally observable only in mutant cells that lack the telomere bouquet, which provides a nuclear microdomain conducive to centromere reassembly1; however, overexpression of Spo11 or Rec8 leads to levels of centromere dismantlement that cannot be countered by the bouquet. Specific nucleosome remodelling factors mediate centromere dismantlement by Spo11 and Rec8. Ectopic expression of either protein in proliferating cells leads to the loss of mitotic kinetochores in both fission yeast and human cells. Hence, while centromeric chromatin has been characterized as extraordinarily stable, Spo11 and Rec8 challenge this stability and may jeopardize kinetochores in cancers that express meiotic proteins.
Collapse
Affiliation(s)
- Haitong Hou
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, 12801 E. 17th Ave, Aurora, CO 80045, Phone 303-724-3203,Former address: Telomere Biology Laboratory, Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892,Co-corresponding authors: ;
| | - Eftychia Kyriacou
- Former address: Telomere Biology Laboratory, Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892,Current address: Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Rahul Thadani
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, 12801 E. 17th Ave, Aurora, CO 80045, Phone 303-724-3203,Former address: Telomere Biology Laboratory, Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892
| | - Michael Klutstein
- Chromatin and Aging Research Laboratory, Institute of Dental Science, Hebrew University of Jerusalem PO 12272, Israel 91120
| | - Joseph H. Chapman
- Former address: Telomere Biology Laboratory, Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892,Current address: Single Molecular Biophysics Laboratory, NHLBI, NIH
| | - Julia Promisel Cooper
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, 12801 E. 17th Ave, Aurora, CO 80045, Phone 303-724-3203,Former address: Telomere Biology Laboratory, Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892,Co-corresponding authors: ;
| |
Collapse
|
18
|
Schüller A, Wolansky L, Berger H, Studt L, Gacek-Matthews A, Sulyok M, Strauss J. A novel fungal gene regulation system based on inducible VPR-dCas9 and nucleosome map-guided sgRNA positioning. Appl Microbiol Biotechnol 2020; 104:9801-9822. [PMID: 33006690 PMCID: PMC7595996 DOI: 10.1007/s00253-020-10900-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/31/2020] [Accepted: 09/08/2020] [Indexed: 12/16/2022]
Abstract
Programmable transcriptional regulation is a powerful tool to study gene functions. Current methods to selectively regulate target genes are mainly based on promoter exchange or on overexpressing transcriptional activators. To expand the discovery toolbox, we designed a dCas9-based RNA-guided synthetic transcription activation system for Aspergillus nidulans that uses enzymatically disabled "dead" Cas9 fused to three consecutive activation domains (VPR-dCas9). The dCas9-encoding gene is under the control of an estrogen-responsive promoter to allow induction timing and to avoid possible negative effects by strong constitutive expression of the highly active VPR domains. Especially in silent genomic regions, facultative heterochromatin and strictly positioned nucleosomes can constitute a relevant obstacle to the transcriptional machinery. To avoid this negative impact and to facilitate optimal positioning of RNA-guided VPR-dCas9 to targeted promoters, we have created a genome-wide nucleosome map from actively growing cells and stationary cultures to identify the cognate nucleosome-free regions (NFRs). Based on these maps, different single-guide RNAs (sgRNAs) were designed and tested for their targeting and activation potential. Our results demonstrate that the system can be used to regulate several genes in parallel and, depending on the VPR-dCas9 positioning, expression can be pushed to very high levels. We have used the system to turn on individual genes within two different biosynthetic gene clusters (BGCs) which are silent under normal growth conditions. This method also opens opportunities to stepwise activate individual genes in a cluster to decipher the correlated biosynthetic pathway. Graphical abstract KEYPOINTS: • An inducible RNA-guided transcriptional regulator based on VPR-dCas9 was established in Aspergillus nidulans. • Genome-wide nucleosome positioning maps were created that facilitate sgRNA positioning. • The system was successfully applied to activate genes within two silent biosynthetic gene clusters.
Collapse
Affiliation(s)
- Andreas Schüller
- Fungal Genetics Lab, Institute of Microbial Genetics, Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences Vienna, BOKU-Campus Tulln, Konrad Lorenz Strasse 24, A-3430, Tulln an der Donau, Austria
| | - Lisa Wolansky
- Institute Krems Bioanalytics , IMC FH Krems University of Applied Sciences , Krems, Austria
| | - Harald Berger
- Fungal Genetics Lab, Institute of Microbial Genetics, Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences Vienna, BOKU-Campus Tulln, Konrad Lorenz Strasse 24, A-3430, Tulln an der Donau, Austria
| | - Lena Studt
- Fungal Genetics Lab, Institute of Microbial Genetics, Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences Vienna, BOKU-Campus Tulln, Konrad Lorenz Strasse 24, A-3430, Tulln an der Donau, Austria
| | - Agnieszka Gacek-Matthews
- Fungal Genetics Lab, Institute of Microbial Genetics, Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences Vienna, BOKU-Campus Tulln, Konrad Lorenz Strasse 24, A-3430, Tulln an der Donau, Austria
- Institute of Microbiology, Functional Microbiology Division, University of Veterinary Sciences Vienna, Wien, Austria
| | - Michael Sulyok
- Institute of Bioanalytics and Agrometabolomics, Department of Agrobiotechnology, BOKU-University of Natural Resources and Life Sciences Vienna, BOKU-Campus Tulln, Konrad-Lorenz-Straße 20, A-3430 Tulln an der Donau, Austria
| | - Joseph Strauss
- Fungal Genetics Lab, Institute of Microbial Genetics, Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences Vienna, BOKU-Campus Tulln, Konrad Lorenz Strasse 24, A-3430, Tulln an der Donau, Austria.
| |
Collapse
|
19
|
Wong CYY, Lee BCH, Yuen KWY. Epigenetic regulation of centromere function. Cell Mol Life Sci 2020; 77:2899-2917. [PMID: 32008088 PMCID: PMC11105045 DOI: 10.1007/s00018-020-03460-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 12/23/2019] [Accepted: 01/10/2020] [Indexed: 12/20/2022]
Abstract
The centromere is a specialized region on the chromosome that directs equal chromosome segregation. Centromeres are usually not defined by DNA sequences alone. How centromere formation and function are determined by epigenetics is still not fully understood. Active centromeres are often marked by the presence of centromeric-specific histone H3 variant, centromere protein A (CENP-A). How CENP-A is assembled into the centromeric chromatin during the cell cycle and propagated to the next cell cycle or the next generation to maintain the centromere function has been intensively investigated. In this review, we summarize current understanding of how post-translational modifications of CENP-A and other centromere proteins, centromeric and pericentric histone modifications, non-coding transcription and transcripts contribute to centromere function, and discuss their intricate relationships and potential feedback mechanisms.
Collapse
Affiliation(s)
- Charmaine Yan Yu Wong
- School of Biological Sciences, The University of Hong Kong, Kadoorie Biological Sciences Building, Pokfulam Road, Hong Kong, China
| | - Bernard Chi Hang Lee
- School of Biological Sciences, The University of Hong Kong, Kadoorie Biological Sciences Building, Pokfulam Road, Hong Kong, China
| | - Karen Wing Yee Yuen
- School of Biological Sciences, The University of Hong Kong, Kadoorie Biological Sciences Building, Pokfulam Road, Hong Kong, China.
| |
Collapse
|
20
|
Guin K, Sreekumar L, Sanyal K. Implications of the Evolutionary Trajectory of Centromeres in the Fungal Kingdom. Annu Rev Microbiol 2020; 74:835-853. [PMID: 32706633 DOI: 10.1146/annurev-micro-011720-122512] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Chromosome segregation during the cell cycle is an evolutionarily conserved, fundamental biological process. Dynamic interaction between spindle microtubules and the kinetochore complex that assembles on centromere DNA is required for faithful chromosome segregation. The first artificial minichromosome was constructed by cloning the centromere DNA of the budding yeast Saccharomyces cerevisiae. Since then, centromeres have been identified in >60 fungal species. The DNA sequence and organization of the sequence elements are highly diverse across these fungal centromeres. In this article, we provide a comprehensive view of the evolution of fungal centromeres. Studies of this process facilitated the identification of factors influencing centromere specification, maintenance, and propagation through many generations. Additionally, we discuss the unique features and plasticity of centromeric chromatin and the involvement of centromeres in karyotype evolution. Finally, we discuss the implications of recurrent loss of RNA interference (RNAi) and/or heterochromatin components on the trajectory of the evolution of fungal centromeres and propose the centromere structure of the last common ancestor of three major fungal phyla-Ascomycota, Basidiomycota, and Mucoromycota.
Collapse
Affiliation(s)
- Krishnendu Guin
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Karnataka 560064, India; , ,
| | - Lakshmi Sreekumar
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Karnataka 560064, India; , ,
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Karnataka 560064, India; , ,
| |
Collapse
|
21
|
Ohzeki JI, Otake K, Masumoto H. Human artificial chromosome: Chromatin assembly mechanisms and CENP-B. Exp Cell Res 2020; 389:111900. [PMID: 32044309 DOI: 10.1016/j.yexcr.2020.111900] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 12/12/2022]
Abstract
The centromere is a specialized chromosomal locus required for accurate chromosome segregation. Heterochromatin also assembles around centromere chromatin and forms a base that supports sister chromatid cohesion until anaphase begins. Both centromere chromatin and heterochromatin assemble on a centromeric DNA sequence, a highly repetitive sequence called alphoid DNA (α-satellite DNA) in humans. Alphoid DNA can form a de novo centromere and subsequent human artificial chromosome (HAC) when introduced into the human culture cells HT1080. HAC is maintained stably as a single chromosome independent of other human chromosomes. For de novo centromere assembly and HAC formation, the centromere protein CENP-B and its binding sites, CENP-B boxes, are required in the repeating units of alphoid DNA. CENP-B has multiple roles in de novo centromere chromatin assembly and stabilization and in heterochromatin formation upon alphoid DNA introduction into the cells. Here we review recent progress in human artificial chromosome construction and centromere/heterochromatin assembly and maintenance, focusing on the involvement of human centromere DNA and CENP-B protein.
Collapse
Affiliation(s)
- Jun-Ichirou Ohzeki
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, 292-0818, Japan
| | - Koichiro Otake
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, 292-0818, Japan
| | - Hiroshi Masumoto
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, 292-0818, Japan.
| |
Collapse
|
22
|
Mutation in histone deacetylase clr6 promotes the survival of S. pombe cds1 null mutant in response to hydroxyurea. Mol Genet Genomics 2020; 295:695-703. [PMID: 32124033 DOI: 10.1007/s00438-020-01655-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 02/13/2020] [Indexed: 10/24/2022]
Abstract
Fission yeast Cds1 is responsible for the replication checkpoint activation and helps to protect replication fork collapse in response to hydroxyurea (HU). Here, we investigated the role of histone deacetylase in response to replication fork arrest and observed that in the presence of HU, the survival of cds1Δ cells was improved when the cells were simultaneously treated with histone deacetylase inhibitors. Furthermore, a mutation in the histone deacetylase gene, clr6, also suppresses the growth defect of cds1Δ cells in response to HU indicating a suppressive role of clr6-1 mutation in cds1 deletion background upon HU treatment. Interestingly, in response to HU, phosphorylation of Chk1 kinase and the number of Rad52YFP foci was reduced in cds1Δ clr6-1 double mutant as compared to cds1Δ single mutant indicating a decrease in the level of DNA damage in response to HU. Accordingly, the single-cell gel electrophoresis assay revealed a drastic reduction in the tail length of cds1Δ clr6-1 double mutant as compared to cds1Δ cells in the presence of HU suggesting the suppression of chromosomal defects in the double mutant. Taken together, we proposed that there could be transient suppression of fork collapse in cds1Δ clr6-1 double mutant upon HU treatment due to the delay in mitotic progression that leads to the facilitation of cell growth.
Collapse
|
23
|
Singh PP, Shukla M, White SA, Lafos M, Tong P, Auchynnikava T, Spanos C, Rappsilber J, Pidoux AL, Allshire RC. Hap2-Ino80-facilitated transcription promotes de novo establishment of CENP-A chromatin. Genes Dev 2020; 34:226-238. [PMID: 31919190 PMCID: PMC7000912 DOI: 10.1101/gad.332536.119] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 12/11/2019] [Indexed: 12/13/2022]
Abstract
Centromeres are maintained epigenetically by the presence of CENP-A, an evolutionarily conserved histone H3 variant, which directs kinetochore assembly and hence centromere function. To identify factors that promote assembly of CENP-A chromatin, we affinity-selected solubilized fission yeast CENP-ACnp1 chromatin. All subunits of the Ino80 complex were enriched, including the auxiliary subunit Hap2. Chromatin association of Hap2 is Ies4-dependent. In addition to a role in maintenance of CENP-ACnp1 chromatin integrity at endogenous centromeres, Hap2 is required for de novo assembly of CENP-ACnp1 chromatin on naïve centromere DNA and promotes H3 turnover on centromere regions and other loci prone to CENP-ACnp1 deposition. Prior to CENP-ACnp1 chromatin assembly, Hap2 facilitates transcription from centromere DNA. These analyses suggest that Hap2-Ino80 destabilizes H3 nucleosomes on centromere DNA through transcription-coupled histone H3 turnover, driving the replacement of resident H3 nucleosomes with CENP-ACnp1 nucleosomes. These inherent properties define centromere DNA by directing a program that mediates CENP-ACnp1 assembly on appropriate sequences.
Collapse
Affiliation(s)
- Puneet P. Singh
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Manu Shukla
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Sharon A. White
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Marcel Lafos
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Pin Tong
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Tatsiana Auchynnikava
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Christos Spanos
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom;,Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany
| | - Alison L. Pidoux
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| | - Robin C. Allshire
- Wellcome Centre for Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
| |
Collapse
|
24
|
PHF2 histone demethylase prevents DNA damage and genome instability by controlling cell cycle progression of neural progenitors. Proc Natl Acad Sci U S A 2019; 116:19464-19473. [PMID: 31488723 DOI: 10.1073/pnas.1903188116] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Histone H3 lysine 9 methylation (H3K9me) is essential for cellular homeostasis; however, its contribution to development is not well established. Here, we demonstrate that the H3K9me2 demethylase PHF2 is essential for neural progenitor proliferation in vitro and for early neurogenesis in the chicken spinal cord. Using genome-wide analyses and biochemical assays we show that PHF2 controls the expression of critical cell cycle progression genes, particularly those related to DNA replication, by keeping low levels of H3K9me3 at promoters. Accordingly, PHF2 depletion induces R-loop accumulation that leads to extensive DNA damage and cell cycle arrest. These data reveal a role of PHF2 as a guarantor of genome stability that allows proper expansion of neural progenitors during development.
Collapse
|
25
|
Sreekumar L, Jaitly P, Chen Y, Thimmappa BC, Sanyal A, Sanyal K. Cis- and Trans-chromosomal Interactions Define Pericentric Boundaries in the Absence of Conventional Heterochromatin. Genetics 2019; 212:1121-1132. [PMID: 31142612 PMCID: PMC6707466 DOI: 10.1534/genetics.119.302179] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 05/22/2019] [Indexed: 01/28/2023] Open
Abstract
The diploid budding yeast Candida albicans harbors unique CENPA-rich 3- to 5-kb regions that form the centromere (CEN) core on each of its eight chromosomes. The epigenetic nature of these CENs does not permit the stabilization of a functional kinetochore on an exogenously introduced CEN plasmid. The flexible nature of such centromeric chromatin is exemplified by the reversible silencing of a transgene upon its integration into the CENPA-bound region. The lack of a conventional heterochromatin machinery and the absence of defined boundaries of CENPA chromatin makes the process of CEN specification in this organism elusive. Additionally, upon native CEN deletion, C. albicans can efficiently activate neocentromeres proximal to the native CEN locus, hinting at the importance of CEN-proximal regions. In this study, we examine this CEN-proximity effect and identify factors for CEN specification in C. albicans We exploit a counterselection assay to isolate cells that can silence a transgene when integrated into the CEN-flanking regions. We show that the frequency of reversible silencing of the transgene decreases from the central core of CEN7 to its peripheral regions. Using publicly available C. albicans high-throughput chromosome conformation capture data, we identify a 25-kb region centering on the CENPA-bound core that acts as CEN-flanking compact chromatin (CFCC). Cis- and trans-chromosomal interactions associated with the CFCC spatially segregates it from bulk chromatin. We further show that neocentromere activation on chromosome 7 occurs within this specified region. Hence, this study identifies a specialized CEN-proximal domain that specifies and restricts the centromeric activity to a unique region.
Collapse
Affiliation(s)
- Lakshmi Sreekumar
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Priya Jaitly
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Yao Chen
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore 637551
| | - Bhagya C Thimmappa
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Amartya Sanyal
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore 637551
| | - Kaustuv Sanyal
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| |
Collapse
|
26
|
Regulation of ectopic heterochromatin-mediated epigenetic diversification by the JmjC family protein Epe1. PLoS Genet 2019; 15:e1008129. [PMID: 31206516 PMCID: PMC6576747 DOI: 10.1371/journal.pgen.1008129] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 04/09/2019] [Indexed: 01/28/2023] Open
Abstract
H3K9 methylation (H3K9me) is a conserved marker of heterochromatin, a transcriptionally silent chromatin structure. Knowledge of the mechanisms for regulating heterochromatin distribution is limited. The fission yeast JmjC domain-containing protein Epe1 localizes to heterochromatin mainly through its interaction with Swi6, a homologue of heterochromatin protein 1 (HP1), and directs JmjC-mediated H3K9me demethylation in vivo. Here, we found that loss of epe1 (epe1Δ) induced a red-white variegated phenotype in a red-pigment accumulation background that generated uniform red colonies. Analysis of isolated red and white colonies revealed that silencing of genes involved in pigment accumulation by stochastic ectopic heterochromatin formation led to white colony formation. In addition, genome-wide analysis of red- and white-isolated clones revealed that epe1Δ resulted in a heterogeneous heterochromatin distribution among clones. We found that Epe1 had an N-terminal domain distinct from its JmjC domain, which activated transcription in both fission and budding yeasts. The N-terminal transcriptional activation (NTA) domain was involved in suppression of ectopic heterochromatin-mediated red-white variegation. We introduced a single copy of Epe1 into epe1Δ clones harboring ectopic heterochromatin, and found that Epe1 could reduce H3K9me from ectopic heterochromatin but some of the heterochromatin persisted. This persistence was due to a latent H3K9me source embedded in ectopic heterochromatin. Epe1H297A, a canonical JmjC mutant, suppressed red-white variegation, but entirely failed to remove already-established ectopic heterochromatin, suggesting that Epe1 prevented stochastic de novo deposition of ectopic H3K9me in an NTA-dependent but JmjC-independent manner, while its JmjC domain mediated removal of H3K9me from established ectopic heterochromatin. Our results suggest that Epe1 not only limits the distribution of heterochromatin but also controls the balance between suppression and retention of heterochromatin-mediated epigenetic diversification. Suppression of unscheduled epigenetic alterations is important for maintenance of homogeneity among clones, while emergence of epigenetic differences is also important for adaptation or differentiation. The mechanisms that balance both processes warrant further investigation. Epe1, a fission yeast JmjC domain-containing protein, is thought to be an H3K9me demethylase that targets ectopic heterochromatin via its JmjC-dependent demethylation function. Here we found that loss of epe1 induced stochastic ectopic heterochromatin formation genome-wide, suggesting that the fission yeast genome had multiple potential heterochromatin formation sites, which were protected by Epe1. We found that Epe1 prevented deposition of ectopic H3K9me independently of its JmjC-mediated demethylation before heterochromatin establishment. By contrast, Epe1 could attack already-established ectopic heterochromatin via its JmjC domain, but demethylation was not 100% effective, which provided a basis for epigenetic variation. Together, our findings indicate that Epe1 is involved in both maintenance and alteration of heterochromatin distribution, and shed light on the mechanisms controlling individual-specific epigenome profiles.
Collapse
|
27
|
Sneppen K, Ringrose L. Theoretical analysis of Polycomb-Trithorax systems predicts that poised chromatin is bistable and not bivalent. Nat Commun 2019; 10:2133. [PMID: 31086177 PMCID: PMC6513952 DOI: 10.1038/s41467-019-10130-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 04/12/2019] [Indexed: 12/15/2022] Open
Abstract
Polycomb (PcG) and Trithorax (TrxG) group proteins give stable epigenetic memory of silent and active gene expression states, but also allow poised states in pluripotent cells. Here we systematically address the relationship between poised, active and silent chromatin, by integrating 73 publications on PcG/TrxG biochemistry into a mathematical model comprising 144 nucleosome modification states and 8 enzymatic reactions. Our model predicts that poised chromatin is bistable and not bivalent. Bivalent chromatin, containing opposing active and silent modifications, is present as an unstable background population in all system states, and different subtypes co-occur with active and silent chromatin. In contrast, bistability, in which the system switches frequently between stable active and silent states, occurs under a wide range of conditions at the transition between monostable active and silent system states. By proposing that bistability and not bivalency is associated with poised chromatin, this work has implications for understanding the molecular nature of pluripotency. Polycomb and Trithorax group proteins regulate silent and active gene expression states, but also allow poised states in pluripotent cells. Here the authors present a mathematical model that integrates data on Polycomb/ Trithorax biochemistry into a single coherent framework which predicts that poised chromatin is not bivalent as previously proposed, but is bistable, meaning that the system switches frequently between stable active and silent states.
Collapse
Affiliation(s)
- Kim Sneppen
- Center for Models of Life, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen, Denmark.
| | - Leonie Ringrose
- Integrated Research Institute for Life Sciences, Humboldt-Universität zu Berlin, Philippstrasse 13, Haus 22, 10115, Berlin, Germany.
| |
Collapse
|
28
|
Ohzeki J, Larionov V, Earnshaw WC, Masumoto H. De novo formation and epigenetic maintenance of centromere chromatin. Curr Opin Cell Biol 2019; 58:15-25. [PMID: 30654232 DOI: 10.1016/j.ceb.2018.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 11/30/2018] [Accepted: 12/07/2018] [Indexed: 12/12/2022]
Abstract
Accurate chromosome segregation is essential for cell proliferation. The centromere is a specialized chromosomal locus, on which the kinetochore structure is formed. The centromere/kinetochore is required for the equal separation of sister chromatids to daughter cells. Here, we review recent findings on centromere-specific chromatin, including its constitutive protein components, its de novo formation and maintenance mechanisms, and our progress in analyses with synthetic human artificial chromosomes (HACs).
Collapse
Affiliation(s)
- Junichirou Ohzeki
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Vladimir Larionov
- Genome Structure and Function Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Hiroshi Masumoto
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan.
| |
Collapse
|
29
|
Ugolini I, Halic M. Fidelity in RNA-based recognition of transposable elements. Philos Trans R Soc Lond B Biol Sci 2018; 373:rstb.2018.0168. [PMID: 30397104 PMCID: PMC6232588 DOI: 10.1098/rstb.2018.0168] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2018] [Indexed: 12/28/2022] Open
Abstract
Genomes are under constant threat of invasion by transposable elements and other genomic parasites. How can host genomes recognize these elements and target them for degradation? This requires a system that is highly adaptable, and at the same time highly specific. Current data suggest that perturbation of transcription patterns by transposon insertions could be detected by the RNAi surveillance pathway. Multiple transposon insertions might generate sufficient amounts of primal small RNAs to initiate generation of secondary small RNAs and silencing. At the same time primal small RNAs need to be constantly degraded to reduce the level of noise small RNAs below the threshold required for initiation of silencing. Failure in RNA degradation results in loss of fidelity of small RNA pathways and silencing of ectopic targets. This article is part of the theme issue ‘5′ and 3′ modifications controlling RNA degradation’.
Collapse
Affiliation(s)
- Ilaria Ugolini
- Department of Biochemistry and Gene Center, LMU Munich, 81377 Munich, Germany
| | - Mario Halic
- Department of Biochemistry and Gene Center, LMU Munich, 81377 Munich, Germany
| |
Collapse
|
30
|
Lu M, He X. Ccp1 modulates epigenetic stability at centromeres and affects heterochromatin distribution in Schizosaccharomyces pombe. J Biol Chem 2018; 293:12068-12080. [PMID: 29899117 PMCID: PMC6078436 DOI: 10.1074/jbc.ra118.003873] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 06/02/2018] [Indexed: 12/26/2022] Open
Abstract
Distinct chromatin organization features, such as centromeres and heterochromatin domains, are inherited epigenetically. However, the mechanisms that modulate the accuracy of epigenetic inheritance, especially at the individual nucleosome level, are not well-understood. Here, using ChIP and next-generation sequencing (ChIP-Seq), we characterized Ccp1, a homolog of the histone chaperone Vps75 in budding yeast that functions in centromere chromatin duplication and heterochromatin maintenance in fission yeast (Schizosaccharomyces pombe). We show that Ccp1 is enriched at the central core regions of the centromeres. Of note, among all histone chaperones characterized, deletion of the ccp1 gene uniquely reduced the rate of epigenetic switching, manifested as position effect variegation within the centromeric core region (CEN-PEV). In contrast, gene deletion of other histone chaperones either elevated the PEV switching rates or did not affect centromeric PEV. Ccp1 and the kinetochore components Mis6 and Sim4 were mutually dependent for centromere or kinetochore association at the proper levels. Moreover, Ccp1 influenced heterochromatin distribution at multiple loci in the genome, including the subtelomeric and the pericentromeric regions. We also found that Gar2, a protein predominantly enriched in the nucleolus, functions similarly to Ccp1 in modulating the epigenetic stability of centromeric regions, although its mechanism remained unclear. Together, our results identify Ccp1 as an important player in modulating epigenetic stability and maintaining proper organization of multiple chromatin domains throughout the fission yeast genome.
Collapse
Affiliation(s)
- Min Lu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xiangwei He
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang 310058, China.
| |
Collapse
|
31
|
Greenstein RA, Jones SK, Spivey EC, Rybarski JR, Finkelstein IJ, Al-Sady B. Noncoding RNA-nucleated heterochromatin spreading is intrinsically labile and requires accessory elements for epigenetic stability. eLife 2018; 7:32948. [PMID: 30020075 PMCID: PMC6070336 DOI: 10.7554/elife.32948] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 07/17/2018] [Indexed: 12/22/2022] Open
Abstract
The heterochromatin spreading reaction is a central contributor to the formation of gene-repressive structures, which are re-established with high positional precision, or fidelity, following replication. How the spreading reaction contributes to this fidelity is not clear. To resolve the origins of stable inheritance of repression, we probed the intrinsic character of spreading events in fission yeast using a system that quantitatively describes the spreading reaction in live single cells. We show that spreading triggered by noncoding RNA-nucleated elements is stochastic, multimodal, and fluctuates dynamically across time. This lack of stability correlates with high histone turnover. At the mating type locus, this unstable behavior is restrained by an accessory cis-acting element REIII, which represses histone turnover. Further, REIII safeguards epigenetic memory against environmental perturbations. Our results suggest that the most prevalent type of spreading, driven by noncoding RNA-nucleators, is epigenetically unstable and requires collaboration with accessory elements to achieve high fidelity.
Collapse
Affiliation(s)
- R A Greenstein
- Department of Microbiology & Immunology, George Williams Hooper Foundation, University of California San Francisco, San Francisco, United States.,TETRAD graduate program, University of California San Francisco, San Francisco, United States
| | - Stephen K Jones
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
| | - Eric C Spivey
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
| | - James R Rybarski
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, United States.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, United States
| | - Bassem Al-Sady
- Department of Microbiology & Immunology, George Williams Hooper Foundation, University of California San Francisco, San Francisco, United States
| |
Collapse
|
32
|
A Heterochromatin Domain Forms Gradually at a New Telomere and Is Dynamic at Stable Telomeres. Mol Cell Biol 2018; 38:MCB.00393-17. [PMID: 29784772 PMCID: PMC6048312 DOI: 10.1128/mcb.00393-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 05/09/2018] [Indexed: 02/03/2023] Open
Abstract
Heterochromatin domains play important roles in chromosome biology, organismal development, and aging, including centromere function, mammalian female X chromosome inactivation, and senescence-associated heterochromatin foci. In the fission yeast Schizosaccharomyces pombe and metazoans, heterochromatin contains histone H3 that is dimethylated at lysine 9. Heterochromatin domains play important roles in chromosome biology, organismal development, and aging, including centromere function, mammalian female X chromosome inactivation, and senescence-associated heterochromatin foci. In the fission yeast Schizosaccharomyces pombe and metazoans, heterochromatin contains histone H3 that is dimethylated at lysine 9. While factors required for heterochromatin have been identified, the dynamics of heterochromatin formation are poorly understood. Telomeres convert adjacent chromatin into heterochromatin. To form a new heterochromatic region in S. pombe, an inducible DNA double-strand break (DSB) was engineered next to 48 bp of telomere repeats in euchromatin, which caused formation of a new telomere and the establishment and gradual spreading of a new heterochromatin domain. However, spreading was dynamic even after the telomere had reached its stable length, with reporter genes within the heterochromatin domain showing variegated expression. The system also revealed the presence of repeats located near the boundaries of euchromatin and heterochromatin that are oriented to allow the efficient healing of a euchromatic DSB to cap the chromosome end with a new telomere. Telomere formation in S. pombe therefore reveals novel aspects of heterochromatin dynamics and fail-safe mechanisms to repair subtelomeric breaks, with implications for similar processes in metazoan genomes.
Collapse
|
33
|
Epigenetic inheritance mediated by coupling of RNAi and histone H3K9 methylation. Nature 2018; 558:615-619. [PMID: 29925950 PMCID: PMC6312107 DOI: 10.1038/s41586-018-0239-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 04/30/2018] [Indexed: 02/06/2023]
Abstract
Histone posttranslational modifications (PTMs) are associated with epigenetic states that form the basis for cell type specific gene expression1,2. Once established, histone PTMs can be maintained by positive feedback involving enzymes that recognize and catalyze the same modification on newly deposited histones. Recent studies suggest that in wild-type cells, histone PTM-based positive feedback is too weak to mediate epigenetic inheritance in the absence of other inputs3–7. RNAi-mediated histone H3 lysine 9 methylation (H3K9me) and heterochromatin formation define a potential epigenetic inheritance mechanism in which positive feedback involving small interfering RNA (siRNA) amplification can be directly coupled to histone PTM positive feedback8–14. However, it remains unknown whether such a coupling of two feedback loops can maintain epigenetic silencing independently of DNA sequence and in the absence of enabling mutations that disrupt genome-wide chromatin structure or transcription15–17. Here using fission yeast S. pombe, we show that siRNA-induced H3K9me and silencing of a euchromatic gene can be epigenetically inherited in cis during multiple mitotic and meiotic cell divisions in wild-type cells. This inheritance involves the spreading of secondary siRNAs and H3K9me3 to the targeted gene and surrounding areas and requires both RNAi and H3K9me, suggesting that siRNA and H3K9me positive feedback loops act synergistically to maintain silencing. In contrast, when maintained solely by histone PTM positive feedback, silencing is erased by H3K9 demethylation promoted by Epe1, or by interallelic interactions following mating to cells containing an expressed epiallele even in the absence of Epe1. These findings demonstrate that the RNAi machinery can mediate transgenerational epigenetic inheritance independently of DNA sequence or enabling mutations and reveal a role for the coupling of siRNA and H3K9me positive feedback loops in protection of epigenetic alleles from erasure.
Collapse
|
34
|
The Ino80 complex mediates epigenetic centromere propagation via active removal of histone H3. Nat Commun 2017; 8:529. [PMID: 28904333 PMCID: PMC5597579 DOI: 10.1038/s41467-017-00704-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 07/19/2017] [Indexed: 12/25/2022] Open
Abstract
The centromere is the chromosomal locus at which the kinetochore is assembled to direct chromosome segregation. The histone H3 variant, centromere protein A (CENP-A), is known to epigenetically mark active centromeres, but the mechanism by which CENP-A propagates at the centromere, replacing histone H3, remains poorly understood. Using fission yeast, here we show that the Ino80 adenosine triphosphate (ATP)-dependent chromatin-remodeling complex, which removes histone H3-containing nucleosomes from associated chromatin, promotes CENP-ACnp1 chromatin assembly at the centromere in a redundant manner with another chromatin-remodeling factor Chd1Hrp1. CENP-ACnp1 chromatin actively recruits the Ino80 complex to centromeres to elicit eviction of histone H3-containing nucleosomes. Artificial targeting of Ino80 subunits to a non-centromeric DNA sequence placed in a native centromere enhances the spreading of CENP-ACnp1 chromatin into the non-centromeric DNA. Based on these results, we propose that CENP-ACnp1 chromatin employs the Ino80 complex to mediate the replacement of histone H3 with CENP-ACnp1, and thereby reinforces itself. The histone variant CENP-A marks active centromeres and replaces H3 at centromeres through a poorly understood mechanism. Here, the authors provide evidence that the chromatin remodeller Ino80 promotes CENP-A chromatin assembly at the centromere in fission yeast.
Collapse
|
35
|
Affiliation(s)
- Adam Klosin
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| |
Collapse
|
36
|
Upadhyay U, Srivastava S, Khatri I, Nanda JS, Subramanian S, Arora A, Singh J. Ablation of RNA interference and retrotransposons accompany acquisition and evolution of transposases to heterochromatin protein CENPB. Mol Biol Cell 2017; 28:1132-1146. [PMID: 28228545 PMCID: PMC5391189 DOI: 10.1091/mbc.e16-07-0485] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 01/19/2017] [Accepted: 02/14/2017] [Indexed: 02/02/2023] Open
Abstract
Fission yeast have adapted to retrotransposon invasion by RNAi-mediated silencing, which has coevolved into a mechanism involving CENPB-mediated heterochromatinization together with ablation of RNAi components via accumulation of recombinogenic repeats in recently diverged species of Schizosaccharomyces. Similar trends are seen in the metazoans. Inactivation of retrotransposons is accompanied by the emergence of centromere-binding protein-B (CENPB) in Schizosaccharomyces, as well as in metazoans. The RNA interference (RNAi)-induced transcriptional silencing (RITS) complex, comprising chromodomain protein-1 (Chp1), Tas3 (protein with unknown function), and Argonaute (Ago1), plays an important role in RNAi-mediated heterochromatinization. We find that whereas the Ago1 subunit of the RITS complex is highly conserved, Tas3 is lost and Chp1 is truncated in Schizosaccharomyces cryophilus and Schizosaccharomyces octosporus. We show that truncated Chp1 loses the property of heterochromatin localization and silencing when transformed in Schizosaccharomyces pombe. Furthermore, multiple copies of CENPB, related to Tc1/mariner and Tc5 transposons, occur in all Schizosaccharomyces species, as well as in humans, but with loss of transposase function (except Schizosaccharomyces japonicus). We propose that acquisition of Tc1/mariner and Tc5 elements by horizontal transfer in S. pombe (and humans) is accompanied by alteration of their function from a transposase/endonuclease to a heterochromatin protein, designed to suppress transposon expression and recombination. The resulting redundancy of RITS may have eased the selection pressure, resulting in progressive loss or truncation of tas3 and chp1 genes in S. octosporus and S. cryophilus and triggered similar evolutionary dynamics in the metazoan orthologues.
Collapse
Affiliation(s)
- Udita Upadhyay
- Department of Anesthesiology, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - Suchita Srivastava
- Yeast Epigenetic Regulation Laboratory, Council of Scientific and Industrial Research, Chandigarh 160036, India
| | - Indu Khatri
- Department of Medicine and Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215
| | - Jagpreet Singh Nanda
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106
| | - Srikrishna Subramanian
- Protein Evolution Laboratory, Council of Scientific and Industrial Research, Chandigarh 160036, India
| | - Amit Arora
- Microbial Type Culture Collection, Institute of Microbial Technology, Council of Scientific and Industrial Research, Chandigarh 160036, India
| | - Jagmohan Singh
- Yeast Epigenetic Regulation Laboratory, Council of Scientific and Industrial Research, Chandigarh 160036, India
| |
Collapse
|
37
|
Koyama M, Nagakura W, Tanaka H, Kujirai T, Chikashige Y, Haraguchi T, Hiraoka Y, Kurumizaka H. In vitro reconstitution and biochemical analyses of the Schizosaccharomyces pombe nucleosome. Biochem Biophys Res Commun 2016; 482:896-901. [PMID: 27890612 DOI: 10.1016/j.bbrc.2016.11.130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Accepted: 11/23/2016] [Indexed: 10/20/2022]
Abstract
Schizosaccharomyces pombe, which has a small genome but shares many physiological functions with higher eukaryotes, is a useful single-cell, model eukaryotic organism. In particular, many features concerning chromatin structure and dynamics, including heterochromatin, centromeres, telomeres, and DNA replication origins, are well conserved between S. pombe and higher eukaryotes. However, the S. pombe nucleosome, the fundamental structural unit of chromatin, has not been reconstituted in vitro. In the present study, we established the method to purify S. pombe histones H2A, H2B, H3, and H4, and successfully reconstituted the S. pombe nucleosome in vitro. Our thermal stability assay and micrococcal nuclease treatment assay revealed that the S. pombe nucleosome is markedly unstable and its DNA ends are quite accessible, as compared to the canonical human nucleosome. These findings are important to understand the mechanisms of epigenetic genomic DNA regulation in fission yeast.
Collapse
Affiliation(s)
- Masako Koyama
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Wataru Nagakura
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Hiroki Tanaka
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Tomoya Kujirai
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
| | - Yuji Chikashige
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan; Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasushi Hiraoka
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan; Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan; Research Institute for Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan; Institute for Medical-oriented Structural Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.
| |
Collapse
|
38
|
Cam HP, Whitehall S. Analysis of Heterochromatin in Schizosaccharomyces pombe. Cold Spring Harb Protoc 2016; 2016:2016/11/pdb.top079889. [PMID: 27803258 DOI: 10.1101/pdb.top079889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This introduction briefly describes the biology of heterochromatin in the fission yeast Schizosaccharomyces pombe We highlight some of the salient features of fission yeast that render it an excellent unicellular eukaryote for studying heterochromatin. We then discuss key aspects of heterochromatin that are of interest to those in the field, and last we introduce experimental approaches often used to investigate heterochromatin.
Collapse
Affiliation(s)
- Hugh P Cam
- Biology Department, Boston College, Chestnut Hill, Massachusetts 02467
| | - Simon Whitehall
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle NE2 4HH, United Kingdom
| |
Collapse
|
39
|
Fransz P, Linc G, Lee C, Aflitos SA, Lasky JR, Toomajian C, Ali H, Peters J, van Dam P, Ji X, Kuzak M, Gerats T, Schubert I, Schneeberger K, Colot V, Martienssen R, Koornneef M, Nordborg M, Juenger TE, de Jong H, Schranz ME. Molecular, genetic and evolutionary analysis of a paracentric inversion in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 88:159-178. [PMID: 27436134 PMCID: PMC5113708 DOI: 10.1111/tpj.13262] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 06/29/2016] [Accepted: 07/01/2016] [Indexed: 05/02/2023]
Abstract
Chromosomal inversions can provide windows onto the cytogenetic, molecular, evolutionary and demographic histories of a species. Here we investigate a paracentric 1.17-Mb inversion on chromosome 4 of Arabidopsis thaliana with nucleotide precision of its borders. The inversion is created by Vandal transposon activity, splitting an F-box and relocating a pericentric heterochromatin segment in juxtaposition with euchromatin without affecting the epigenetic landscape. Examination of the RegMap panel and the 1001 Arabidopsis genomes revealed more than 170 inversion accessions in Europe and North America. The SNP patterns revealed historical recombinations from which we infer diverse haplotype patterns, ancient introgression events and phylogenetic relationships. We find a robust association between the inversion and fecundity under drought. We also find linkage disequilibrium between the inverted region and the early flowering Col-FRIGIDA allele. Finally, SNP analysis elucidates the origin of the inversion to South-Eastern Europe approximately 5000 years ago and the FRI-Col allele to North-West Europe, and reveals the spreading of a single haplotype to North America during the 17th to 19th century. The 'American haplotype' was identified from several European localities, potentially due to return migration.
Collapse
Affiliation(s)
- Paul Fransz
- Department of Plant Development and (Epi)GeneticsSwammerdam Institute for Life SciencesUniversity of AmsterdamAmsterdamthe Netherlands
| | - Gabriella Linc
- Department of Plant Development and (Epi)GeneticsSwammerdam Institute for Life SciencesUniversity of AmsterdamAmsterdamthe Netherlands
- Present address: Centre for Agricultural ResearchHungarian Academy of SciencesAgricultural InstituteMartonvásárHungary
| | - Cheng‐Ruei Lee
- Gregor Mendel Institute (GMI)Austrian Academy of SciencesVienna Biocenter (VBC)Dr Bohr‐Gasse 3Vienna1030Austria
| | | | - Jesse R. Lasky
- Department of BiologyPennsylvania State UniversityUniversity ParkPAUSA
| | | | - Hoda Ali
- Department of Cytogenetics and Genome AnalysisThe Leibniz Institute of Plant Genetics and Crop Plant Research (IPK)GaterslebenGermany
- Present address: Department of Genetics and CytologyNational Research CenterCairoEgypt
| | - Janny Peters
- Section Plant GeneticsInstitute for Wetland and Water Research Faculty of ScienceRadboud UniversityNijmegenthe Netherlands
| | - Peter van Dam
- Section Plant GeneticsInstitute for Wetland and Water Research Faculty of ScienceRadboud UniversityNijmegenthe Netherlands
- Present address: Department of Molecular Plant PathologyUniversity of AmsterdamAmsterdamThe Netherlands
| | - Xianwen Ji
- Laboratory of GeneticsWageningen UniversityWageningenthe Netherlands
| | - Mateusz Kuzak
- MAD, Dutch Genomics Service & Support ProviderSwammerdam Institute for Life SciencesUniversity of AmsterdamAmsterdamthe Netherlands
- Present address: Netherlands eScience CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Tom Gerats
- Section Plant GeneticsInstitute for Wetland and Water Research Faculty of ScienceRadboud UniversityNijmegenthe Netherlands
| | - Ingo Schubert
- Department of Cytogenetics and Genome AnalysisThe Leibniz Institute of Plant Genetics and Crop Plant Research (IPK)GaterslebenGermany
| | | | - Vincent Colot
- Unité de Recherche en Génomique Végétale (URGV)INRA/CNRS/UEVE 2 Rue Gaston CrémieuxEvry Cedex91057France
- Present address: Institut de Biologie de l'Ecole Normale Supérieure (IBENS)ParisFrance
| | - Rob Martienssen
- Cold Spring Harbor LaboratoryCold Spring HarborNew YorkNY11724USA
| | - Maarten Koornneef
- Laboratory of GeneticsWageningen UniversityWageningenthe Netherlands
- Max Planck Institute for Plant Breeding ResearchKöln50829Germany
| | - Magnus Nordborg
- Gregor Mendel Institute (GMI)Austrian Academy of SciencesVienna Biocenter (VBC)Dr Bohr‐Gasse 3Vienna1030Austria
| | | | - Hans de Jong
- Laboratory of GeneticsWageningen UniversityWageningenthe Netherlands
| | | |
Collapse
|
40
|
Histone H3K9 methylation is dispensable for Caenorhabditis elegans development but suppresses RNA:DNA hybrid-associated repeat instability. Nat Genet 2016; 48:1385-1395. [DOI: 10.1038/ng.3672] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 08/22/2016] [Indexed: 12/14/2022]
|
41
|
Burrack LS, Hutton HF, Matter KJ, Clancey SA, Liachko I, Plemmons AE, Saha A, Power EA, Turman B, Thevandavakkam MA, Ay F, Dunham MJ, Berman J. Neocentromeres Provide Chromosome Segregation Accuracy and Centromere Clustering to Multiple Loci along a Candida albicans Chromosome. PLoS Genet 2016; 12:e1006317. [PMID: 27662467 PMCID: PMC5035033 DOI: 10.1371/journal.pgen.1006317] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 08/23/2016] [Indexed: 02/07/2023] Open
Abstract
Assembly of kinetochore complexes, involving greater than one hundred proteins, is essential for chromosome segregation and genome stability. Neocentromeres, or new centromeres, occur when kinetochores assemble de novo, at DNA loci not previously associated with kinetochore proteins, and they restore chromosome segregation to chromosomes lacking a functional centromere. Neocentromeres have been observed in a number of diseases and may play an evolutionary role in adaptation or speciation. However, the consequences of neocentromere formation on chromosome missegregation rates, gene expression, and three-dimensional (3D) nuclear structure are not well understood. Here, we used Candida albicans, an organism with small, epigenetically-inherited centromeres, as a model system to study the functions of twenty different neocentromere loci along a single chromosome, chromosome 5. Comparison of neocentromere properties relative to native centromere functions revealed that all twenty neocentromeres mediated chromosome segregation, albeit to different degrees. Some neocentromeres also caused reduced levels of transcription from genes found within the neocentromere region. Furthermore, like native centromeres, neocentromeres clustered in 3D with active/functional centromeres, indicating that formation of a new centromere mediates the reorganization of 3D nuclear architecture. This demonstrates that centromere clustering depends on epigenetically defined function and not on the primary DNA sequence, and that neocentromere function is independent of its distance from the native centromere position. Together, the results show that a neocentromere can form at many loci along a chromosome and can support the assembly of a functional kinetochore that exhibits native centromere functions including chromosome segregation accuracy and centromere clustering within the nucleus. The accurate segregation of chromosomes during cell division is essential for maintaining genome integrity. The centromere is the DNA region on each chromosome where assembly of a large protein complex, the kinetochore, is required to maintain proper chromosome segregation. In addition, active centromeres exhibit a specific three-dimensional organization within the nucleus: the centromeres associate with one another in a clustered manner. Neocentromeres, or new centromeres, appear at new places along the chromosome when a native centromere becomes non-functional. We used a yeast model, Candida albicans, and isolated twenty instances in which neocentromeres had formed at different positions. All of these neocentromeres were able to direct chromosome segregation, but some had increased error rates. Like native centromeres, these neocentromeres cluster in the nucleus with the other active centromeres. This implies that formation of a neocentromere leads to reorganization of the three-dimensional structure of the nucleus so that different regions of the chromosome are in closer contact to regions of other chromosomes. Recent work suggests that approximately 3% of cancers may contain chromosomes with neocentromeres. Our observations that many neocentromeres have increased error rates provides insight into genome instability in cancer cells. Changes in chromosome copy number may benefit the cancer cells by increasing numbers of oncogenes and/or drug resistance genes, but may also sensitize the cells to chemotherapy approaches that target chromosome segregation mechanisms.
Collapse
Affiliation(s)
- Laura S. Burrack
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Biology, Grinnell College, Grinnell, Iowa, United States of America
- Department of Biology, Gustavus Adolphus College, Saint Peter, Minnesota, United States of America
- * E-mail: (LSB); (JB)
| | - Hannah F. Hutton
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Kathleen J. Matter
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Shelly Applen Clancey
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Ivan Liachko
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | | | - Amrita Saha
- Department of Biology, Grinnell College, Grinnell, Iowa, United States of America
| | - Erica A. Power
- Department of Biology, Gustavus Adolphus College, Saint Peter, Minnesota, United States of America
| | - Breanna Turman
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | | | - Ferhat Ay
- La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Maitreya J. Dunham
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Judith Berman
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
- * E-mail: (LSB); (JB)
| |
Collapse
|
42
|
Trim28 Haploinsufficiency Triggers Bi-stable Epigenetic Obesity. Cell 2016; 164:353-64. [PMID: 26824653 PMCID: PMC4735019 DOI: 10.1016/j.cell.2015.12.025] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/12/2015] [Accepted: 12/08/2015] [Indexed: 12/21/2022]
Abstract
More than one-half billion people are obese, and despite progress in genetic research, much of the heritability of obesity remains enigmatic. Here, we identify a Trim28-dependent network capable of triggering obesity in a non-Mendelian, “on/off” manner. Trim28+/D9 mutant mice exhibit a bi-modal body-weight distribution, with isogenic animals randomly emerging as either normal or obese and few intermediates. We find that the obese-“on” state is characterized by reduced expression of an imprinted gene network including Nnat, Peg3, Cdkn1c, and Plagl1 and that independent targeting of these alleles recapitulates the stochastic bi-stable disease phenotype. Adipose tissue transcriptome analyses in children indicate that humans too cluster into distinct sub-populations, stratifying according to Trim28 expression, transcriptome organization, and obesity-associated imprinted gene dysregulation. These data provide evidence of discrete polyphenism in mouse and man and thus carry important implications for complex trait genetics, evolution, and medicine. Video Abstract
Trim28 haploinsufficiency triggers stochastic bi-stable obesity or polyphenism Non-classical imprinted gene dysregulation specifies “on” versus “off” obese states Peg3 and Nnat perturbation trigger stochastic bi-stable obesity Human BMI distributions and transcriptomes suggest Trim28-associated subpopulations
Collapse
|
43
|
Ohzeki JI, Shono N, Otake K, Martins NMC, Kugou K, Kimura H, Nagase T, Larionov V, Earnshaw WC, Masumoto H. KAT7/HBO1/MYST2 Regulates CENP-A Chromatin Assembly by Antagonizing Suv39h1-Mediated Centromere Inactivation. Dev Cell 2016; 37:413-27. [PMID: 27270040 PMCID: PMC4906249 DOI: 10.1016/j.devcel.2016.05.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 04/08/2016] [Accepted: 05/09/2016] [Indexed: 01/01/2023]
Abstract
Centromere chromatin containing histone H3 variant CENP-A is required for accurate chromosome segregation as a foundation for kinetochore assembly. Human centromere chromatin assembles on a part of the long α-satellite (alphoid) DNA array, where it is flanked by pericentric heterochromatin. Heterochromatin spreads into adjacent chromatin and represses gene expression, and it can antagonize centromere function or CENP-A assembly. Here, we demonstrate an interaction between CENP-A assembly factor M18BP1 and acetyltransferase KAT7/HBO1/MYST2. Knocking out KAT7 in HeLa cells reduced centromeric CENP-A assembly. Mitotic chromosome misalignment and micronuclei formation increased in the knockout cells and were enhanced when the histone H3-K9 trimethylase Suv39h1 was overproduced. Tethering KAT7 to an ectopic alphoid DNA integration site removed heterochromatic H3K9me3 modification and was sufficient to stimulate new CENP-A or histone H3.3 assembly. Thus, KAT7-containing acetyltransferases associating with the Mis18 complex provides competence for histone turnover/exchange activity on alphoid DNA and prevents Suv39h1-mediated heterochromatin invasion into centromeres.
Collapse
Affiliation(s)
- Jun-Ichirou Ohzeki
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Nobuaki Shono
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Koichiro Otake
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Nuno M C Martins
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Kazuto Kugou
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Hiroshi Kimura
- Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Takahiro Nagase
- Public Relations Team, Kazusa DNA Research Institute, Kisarazu 292-0818, Japan
| | - Vladimir Larionov
- Genome Structure and Function Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Hiroshi Masumoto
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan.
| |
Collapse
|
44
|
Freire-Benéitez V, Price RJ, Buscaino A. The Chromatin of Candida albicans Pericentromeres Bears Features of Both Euchromatin and Heterochromatin. Front Microbiol 2016; 7:759. [PMID: 27242771 PMCID: PMC4871872 DOI: 10.3389/fmicb.2016.00759] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 05/05/2016] [Indexed: 01/06/2023] Open
Abstract
Centromeres, sites of kinetochore assembly, are important for chromosome stability and integrity. Most eukaryotes have regional centromeres epigenetically specified by the presence of the histone H3 variant CENP-A. CENP-A chromatin is often surrounded by pericentromeric regions packaged into transcriptionally silent heterochromatin. Candida albicans, the most common human fungal pathogen, possesses small regional centromeres assembled into CENP-A chromatin. The chromatin state of C. albicans pericentromeric regions is unknown. Here, for the first time, we address this question. We find that C. albicans pericentromeres are assembled into an intermediate chromatin state bearing features of both euchromatin and heterochromatin. Pericentromeric chromatin is associated with nucleosomes that are highly acetylated, as found in euchromatic regions of the genome; and hypomethylated on H3K4, as found in heterochromatin. This intermediate chromatin state is inhibitory to transcription and partially represses expression of proximal genes and inserted marker genes. Our analysis identifies a new chromatin state associated with pericentromeric regions.
Collapse
Affiliation(s)
| | - R Jordan Price
- School of Biosciences Canterbury Kent, University of Kent Canterbury, UK
| | - Alessia Buscaino
- School of Biosciences Canterbury Kent, University of Kent Canterbury, UK
| |
Collapse
|
45
|
He H, Zhang S, Wang D, Hochwagen A, Li F. Condensin Promotes Position Effects within Tandem DNA Repeats via the RITS Complex. Cell Rep 2016; 14:1018-1024. [PMID: 26832414 DOI: 10.1016/j.celrep.2016.01.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 10/30/2015] [Accepted: 12/29/2015] [Indexed: 11/28/2022] Open
Abstract
Tandem repetitive DNA is highly abundant in eukaryotic genomes and contributes to transcription control and genome stability. However, how the individual sequences within tandem repeats behave remains largely unknown. Here we develop a collection of fission yeast strains with a reporter gene inserted at different units in a tandem repeat array. We show that, contrary to what is usually assumed, transcriptional silencing and replication timing among the individual repeats differ significantly. RNAi-mediated H3K9 methylation is essential for the silencing position effect. A short hairpin RNA of ura4(+) induces silencing in trans within the tandem array in a position-dependent manner. Importantly, the position effect depends on the condensin subunit, cut3(+). Cut3 promotes the position effect via interaction with the RNA-induced transcriptional silencing (RITS) complex. This study reveals variations in silencing within tandem DNA repeats and provides mechanistic insights into how DNA repeats at the individual level are regulated.
Collapse
Affiliation(s)
- Haijin He
- Department of Biology, New York University, New York, NY 10003-6688, USA
| | - Shu Zhang
- Department of Biology, New York University, New York, NY 10003-6688, USA
| | - Danni Wang
- Department of Biology, New York University, New York, NY 10003-6688, USA
| | - Andreas Hochwagen
- Department of Biology, New York University, New York, NY 10003-6688, USA
| | - Fei Li
- Department of Biology, New York University, New York, NY 10003-6688, USA.
| |
Collapse
|
46
|
Schotanus K, Soyer JL, Connolly LR, Grandaubert J, Happel P, Smith KM, Freitag M, Stukenbrock EH. Histone modifications rather than the novel regional centromeres of Zymoseptoria tritici distinguish core and accessory chromosomes. Epigenetics Chromatin 2015; 8:41. [PMID: 26430472 PMCID: PMC4589918 DOI: 10.1186/s13072-015-0033-5] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/21/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Supernumerary chromosomes have been found in many organisms. In fungi, these "accessory" or "dispensable" chromosomes are present at different frequencies in populations and are usually characterized by higher repetitive DNA content and lower gene density when compared to the core chromosomes. In the reference strain of the wheat pathogen, Zymoseptoria tritici, eight discrete accessory chromosomes have been found. So far, no functional role has been assigned to these chromosomes; however, they have existed as separate entities in the karyotypes of Zymoseptoria species over evolutionary time. In this study, we addressed what-if anything-distinguishes the chromatin of accessory chromosomes from core chromosomes. We used chromatin immunoprecipitation combined with high-throughput sequencing ("ChIP-seq") of DNA associated with the centromere-specific histone H3, CENP-A (CenH3), to identify centromeric DNA, and ChIP-seq with antibodies against dimethylated H3K4, trimethylated H3K9 and trimethylated H3K27 to determine the relative distribution and proportion of euchromatin, obligate and facultative heterochromatin, respectively. RESULTS Centromeres of the eight accessory chromosomes have the same sequence composition and structure as centromeres of the 13 core chromosomes and they are of similar length. Unlike those of most other fungi, Z. tritici centromeres are not composed entirely of repetitive DNA; some centromeres contain only unique DNA sequences, and bona fide expressed genes are located in regions enriched with CenH3. By fluorescence microscopy, we showed that centromeres of Z. tritici do not cluster into a single chromocenter during interphase. We found dramatically higher enrichment of H3K9me3 and H3K27me3 on the accessory chromosomes, consistent with the twofold higher proportion of repetitive DNA and poorly transcribed genes. In contrast, no single histone modification tested here correlated with the distribution of centromeric nucleosomes. CONCLUSIONS All centromeres are similar in length and composed of a mixture of unique and repeat DNA, and most contain actively transcribed genes. Centromeres, subtelomeric regions or telomere repeat length cannot account for the differences in transfer fidelity between core and accessory chromosomes, but accessory chromosomes are greatly enriched in nucleosomes with H3K27 trimethylation. Genes on accessory chromosomes appear to be silenced by trimethylation of H3K9 and H3K27.
Collapse
Affiliation(s)
- Klaas Schotanus
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany ; Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7303 USA ; Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 9-11, 24118 Kiel, Germany ; Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Jessica L Soyer
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany ; INRA, UMR 1290 INRA-AgroParisTech BIOGER, Avenue Lucien Brétignières, Thiverval-Grignon, 78850 France ; Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 9-11, 24118 Kiel, Germany ; Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Lanelle R Connolly
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7303 USA
| | - Jonathan Grandaubert
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany ; Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 9-11, 24118 Kiel, Germany ; 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
| | - Kristina M Smith
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7303 USA
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7303 USA
| | - Eva H Stukenbrock
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany ; Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 9-11, 24118 Kiel, Germany ; Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| |
Collapse
|
47
|
Hoffman CS, Wood V, Fantes PA. An Ancient Yeast for Young Geneticists: A Primer on the Schizosaccharomyces pombe Model System. Genetics 2015; 201:403-23. [PMID: 26447128 PMCID: PMC4596657 DOI: 10.1534/genetics.115.181503] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The fission yeast Schizosaccharomyces pombe is an important model organism for the study of eukaryotic molecular and cellular biology. Studies of S. pombe, together with studies of its distant cousin, Saccharomyces cerevisiae, have led to the discovery of genes involved in fundamental mechanisms of transcription, translation, DNA replication, cell cycle control, and signal transduction, to name but a few processes. However, since the divergence of the two species approximately 350 million years ago, S. pombe appears to have evolved less rapidly than S. cerevisiae so that it retains more characteristics of the common ancient yeast ancestor, causing it to share more features with metazoan cells. This Primer introduces S. pombe by describing the yeast itself, providing a brief description of the origins of fission yeast research, and illustrating some genetic and bioinformatics tools used to study protein function in fission yeast. In addition, a section on some key differences between S. pombe and S. cerevisiae is included for readers with some familiarity with budding yeast research but who may have an interest in developing research projects using S. pombe.
Collapse
Affiliation(s)
- Charles S Hoffman
- Biology Department, Boston College, Chestnut Hill, Massachusetts 02467
| | - Valerie Wood
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, CB2 1GA Cambridge, United Kingdom
| | - Peter A Fantes
- School of Biological Sciences, College of Science and Engineering, University of Edinburgh EH9 3JR Edinburgh, United Kingdom
| |
Collapse
|
48
|
Vanderbilt JN, Gonzalez RF, Allen L, Gillespie A, Leaffer D, Dean WB, Chapin C, Dobbs LG. High-efficiency type II cell-enhanced green fluorescent protein expression facilitates cellular identification, tracking, and isolation. Am J Respir Cell Mol Biol 2015; 53:14-21. [PMID: 25692334 DOI: 10.1165/rcmb.2014-0348ma] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We have developed a transgenic mouse expressing enhanced green fluorescent protein (EGFP) in virtually all type II (TII) alveolar epithelial cells. The CBG mouse (SPC-BAC-EGFP) contains a bacterial artificial chromosome modified to express EGFP within the mouse surfactant protein (SP)-C gene 3' untranslated region. EGFP mRNA expression is limited to the lung. EGFP fluorescence is both limited to and exhibited by all cells expressing pro-SP-C; fluorescence is uniform throughout all lobes of the lung and does not change as mice age. EGFP(+) cells also express SP-B but do not express podoplanin, a type I (TI) cell marker. CBG mice show no evidence of lung disease with aging. In 3 hours, TII cells can be isolated in >99% purity from CBG mice by FACS; the yield of 3.7 ± 0.6 × 10(6) cells represents approximately 25 to 60% of the TII cells in the lung. By FACS analysis, approximately 0.9% of TII cells are in mitosis in uninjured lungs; after bleomycin injury, 4.1% are in mitosis. Because EGFP fluorescence can be detected for >14 days in culture, at a time that SP-C mRNA expression is essentially nil, this line may be useful for tracking TII cells in culture and in vivo. When CBG mice are crossed to transgenic mice expressing rat podoplanin, TI and TII cells can be easily simultaneously identified and isolated. When bred to other strains of mice, EGFP expression can be used to identify TII cells without the need for immunostaining for SP-C. These mice should be useful in models of mouse pulmonary disease and in studies of TII cell biology, biochemistry, and genetics.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Leland G Dobbs
- 1 Cardiovascular Research Institute and.,Departments of 2 Pediatrics and.,3 Medicine, University of California, San Francisco, San Francisco, California
| |
Collapse
|
49
|
Allshire RC, Ekwall K. Epigenetic Regulation of Chromatin States in Schizosaccharomyces pombe. Cold Spring Harb Perspect Biol 2015; 7:a018770. [PMID: 26134317 DOI: 10.1101/cshperspect.a018770] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This article discusses the advances made in epigenetic research using the model organism fission yeast Schizosaccharomyces pombe. S. pombe has been used for epigenetic research since the discovery of position effect variegation (PEV). This is a phenomenon in which a transgene inserted within heterochromatin is variably expressed, but can be stably inherited in subsequent cell generations. PEV occurs at centromeres, telomeres, ribosomal DNA (rDNA) loci, and mating-type regions of S. pombe chromosomes. Heterochromatin assembly in these regions requires enzymes that modify histones and the RNA interference (RNAi) machinery. One of the key histone-modifying enzymes is the lysine methyltransferase Clr4, which methylates histone H3 on lysine 9 (H3K9), a classic hallmark of heterochromatin. The kinetochore is assembled on specialized chromatin in which histone H3 is replaced by the variant CENP-A. Studies in fission yeast have contributed to our understanding of the establishment and maintenance of CENP-A chromatin and the epigenetic activation and inactivation of centromeres.
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
|
50
|
Protacio RU, Storey AJ, Davidson MK, Wahls WP. Nonsense codon suppression in fission yeast due to mutations of tRNA(Ser.11) and translation release factor Sup35 (eRF3). Curr Genet 2015; 61:165-73. [PMID: 25519804 PMCID: PMC4393767 DOI: 10.1007/s00294-014-0465-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 12/01/2014] [Accepted: 12/03/2014] [Indexed: 02/07/2023]
Abstract
In the fission yeast Schizosaccharomyces pombe, sup9 mutations can suppress the termination of translation at nonsense (stop) codons. We localized sup9 physically to the spctrnaser.11 locus and confirmed that one allele (sup9-UGA) alters the anticodon of a serine tRNA. We also found that another purported allele is not allelic. Instead, strains with that suppressor (renamed sup35-F592S) have a single base pair substitution (T1775C) that introduces an amino acid substitution in the Sup35 protein (Sup35-F592S). Reduced functionality of Sup35 (eRF3), the ubiquitous guanine nucleotide-responsive translation release factor of eukaryotes, increases read-through of stop codons. Tetrad dissection revealed that suppression is tightly linked to (inseparable from) the sup35-F592S mutation and that there are no additional extragenic modifiers. The Mendelian inheritance indicates that the Sup35-F592S protein does not adopt an infectious amyloid state ([PSI (+)] prion) to affect suppression, consistent with recent evidence that fission yeast Sup35 does not form prions. We also report that sup9-UGA and sup35-F592S exhibit different strengths of suppression for opal stop codons of ade6-M26 and ade6-M375. We discuss possible mechanisms for the variation in suppressibility exhibited by the two alleles.
Collapse
Affiliation(s)
- Reine U. Protacio
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, 4301 West Markham Street (slot 516), Little Rock, AR 72205-7199, USA
| | - Aaron J. Storey
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, 4301 West Markham Street (slot 516), Little Rock, AR 72205-7199, USA
| | - Mari K. Davidson
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, 4301 West Markham Street (slot 516), Little Rock, AR 72205-7199, USA
| | - Wayne P. Wahls
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, 4301 West Markham Street (slot 516), Little Rock, AR 72205-7199, USA
| |
Collapse
|