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Carotti E, Carducci F, Barucca M, Canapa A, Biscotti MA. Transposable Elements: Epigenetic Silencing Mechanisms or Modulating Tools for Vertebrate Adaptations? Two Sides of the Same Coin. Int J Mol Sci 2023; 24:11591. [PMID: 37511347 PMCID: PMC10380595 DOI: 10.3390/ijms241411591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 07/13/2023] [Accepted: 07/14/2023] [Indexed: 07/30/2023] Open
Abstract
Transposable elements constitute one of the main components of eukaryotic genomes. In vertebrates, they differ in content, typology, and family diversity and played a crucial role in the evolution of this taxon. However, due to their transposition ability, TEs can be responsible for genome instability, and thus silencing mechanisms were evolved to allow the coexistence between TEs and eukaryotic host-coding genes. Several papers are highlighting in TEs the presence of regulatory elements involved in regulating nearby genes in a tissue-specific fashion. This suggests that TEs are not sequences merely to silence; rather, they can be domesticated for the regulation of host-coding gene expression, permitting species adaptation and resilience as well as ensuring human health. This review presents the main silencing mechanisms acting in vertebrates and the importance of exploiting these mechanisms for TE control to rewire gene expression networks, challenging the general view of TEs as threatening elements.
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Affiliation(s)
| | - Federica Carducci
- Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, 60131 Ancona, Italy; (E.C.); (M.B.); (A.C.); (M.A.B.)
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Rybarski JR, Hu K, Hill AM, Wilke CO, Finkelstein IJ. Metagenomic discovery of CRISPR-associated transposons. Proc Natl Acad Sci U S A 2021; 118:e2112279118. [PMID: 34845024 PMCID: PMC8670466 DOI: 10.1073/pnas.2112279118] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 10/26/2021] [Indexed: 12/26/2022] Open
Abstract
CRISPR-associated Tn7 transposons (CASTs) co-opt cas genes for RNA-guided transposition. CASTs are exceedingly rare in genomic databases; recent surveys have reported Tn7-like transposons that co-opt Type I-F, I-B, and V-K CRISPR effectors. Here, we expand the diversity of reported CAST systems via a bioinformatic search of metagenomic databases. We discover architectures for all known CASTs, including arrangements of the Cascade effectors, target homing modalities, and minimal V-K systems. We also describe families of CASTs that have co-opted the Type I-C and Type IV CRISPR-Cas systems. Our search for non-Tn7 CASTs identifies putative candidates that include a nuclease dead Cas12. These systems shed light on how CRISPR systems have coevolved with transposases and expand the programmable gene-editing toolkit.
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Affiliation(s)
- James R Rybarski
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712
| | - Kuang Hu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712
| | - Alexis M Hill
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712
| | - Claus O Wilke
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712;
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712;
- Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX 78712
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Zhu X, Fang H, Gladysz K, Barbour JA, Wong JWH. Overexpression of transposable elements is associated with immune evasion and poor outcome in colorectal cancer. Eur J Cancer 2021; 157:94-107. [PMID: 34492588 DOI: 10.1016/j.ejca.2021.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/28/2021] [Accepted: 08/04/2021] [Indexed: 12/13/2022]
Abstract
AIM High immune cell infiltration of the tumour microenvironment is generally associated with a good prognosis in solid cancers. However, a subset of patients with colorectal cancer (CRC) tumours with high immune cell infiltration have a poor outcome. These tumours have a high level of T cell infiltration and are also characterised by increased expression of programmed death-ligand 1 (PD-L1). As these tumours comprise both microsatellite instability and microsatellite stable subtypes, the mechanism underlying this phenotype is unknown. METHODS Using RNA-seq data from The Cancer Genome Atlas, we quantified transposable element (TE) expression and developed a TE expression score that is predictive of prognosis and immune infiltration independent of microsatellite instability status and tumour staging in CRC. RESULTS Tumours with the highest TE expression score showed increased immune cell infiltration with upregulation of interferon (IFN) signalling pathways and downstream activation of IFN-simulated genes. As expected, cell lines treated with DNA methyltransferase inhibitor mimicked patient tumours with increased TE expression and IFN signalling. However, surprisingly, unlike high TE expressing CRC, there is little evidence for the activation of JAK-STAT signalling and PD-L1 expression in DNA methyltransferase inhibitor-treated cells. Single-cell RNA-seq analysis of CRC samples showed that PD-L1 expression is mainly confined to tumour-associated macrophages and T cells, suggesting that TE mediated IFN signalling is triggering expression of PD-L1 in immune cells rather than in tumour cells. CONCLUSIONS Our study uncovers a novel mechanism of TE driven immune evasion and highlights TE expression as an important factor for patient prognosis in CRC.
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Affiliation(s)
- Xiaoqiang Zhu
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region
| | - Hu Fang
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region
| | - Kornelia Gladysz
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region
| | - Jayne A Barbour
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region
| | - Jason W H Wong
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region; Centre for PanorOmic Sciences, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region.
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Long J, Liu J, Xia A, Springer NM, He Y. Maize decrease in DNA methylation 1 targets RNA-directed DNA methylation on active chromatin. Plant Cell 2021; 33:2183-2196. [PMID: 33779761 PMCID: PMC8364229 DOI: 10.1093/plcell/koab098] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 03/25/2021] [Indexed: 06/01/2023]
Abstract
DNA methylation plays vital roles in repressing transposable element activity and regulating gene expression. The chromatin-remodeling factor Decrease in DNA methylation 1 (DDM1) is crucial for maintaining DNA methylation across diverse plant species, and is required for RNA-directed DNA methylation (RdDM) to maintain mCHH islands in maize (Zea mays). However, the mechanisms by which DDM1 is involved in RdDM are not well understood. In this work, we used chromatin immunoprecipitation coupled with high-throughput sequencing to ascertain the genome-wide occupancy of ZmDDM1 in the maize genome. The results revealed that ZmDDM1 recognized an 8-bp-long GC-rich degenerate DNA sequence motif, which is enriched in transcription start sites and other euchromatic regions. Meanwhile, 24-nucleotide siRNAs and CHH methylation were delineated at the edge of ZmDDM1-occupied sites. ZmDDM1 co-purified with Argonaute 4 (ZmAGO4) proteins, providing further evidence that ZmDDM1 is a component of RdDM complexes in planta. Consistent with this, the vast majority of ZmDDM1-targeted regions co-localized with ZmAGO4-bound genomic sites. Overall, our results suggest a model that ZmDDM1 may be recruited to euchromatic regions via recognition of a GC-rich motif, thereby remodeling chromatin to provide access for RdDM activities in maize.
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Affiliation(s)
- Jincheng Long
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Jinghan Liu
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Aiai Xia
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Nathan M. Springer
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN 55108, USA
| | - Yan He
- MOE Key Laboratory of Crop Heterosis and Utilization, National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
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Sharma V, Thakore P, Majumdar S. THAP9 Transposase Cleaves DNA via Conserved Acidic Residues in an RNaseH-Like Domain. Cells 2021; 10:cells10061351. [PMID: 34072453 PMCID: PMC8230255 DOI: 10.3390/cells10061351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 11/16/2022] Open
Abstract
The catalytic domain of most 'cut and paste' DNA transposases have the canonical RNase-H fold, which is also shared by other polynucleotidyl transferases such as the retroviral integrases and the RAG1 subunit of V(D)J recombinase. The RNase-H fold is a mixture of beta sheets and alpha helices with three acidic residues (Asp, Asp, Glu/Asp-DDE/D) that are involved in the metal-mediated cleavage and subsequent integration of DNA. Human THAP9 (hTHAP9), homologous to the well-studied Drosophila P-element transposase (DmTNP), is an active DNA transposase that, although domesticated, still retains the catalytic activity to mobilize transposons. In this study we have modeled the structure of hTHAP9 using the recently available cryo-EM structure of DmTNP as a template to identify an RNase-H like fold along with important acidic residues in its catalytic domain. Site-directed mutagenesis of the predicted catalytic residues followed by screening for DNA excision and integration activity has led to the identification of candidate Ds and Es in the RNaseH fold that may be a part of the catalytic triad in hTHAP9. This study has helped widen our knowledge about the catalytic activity of a functionally uncharacterized transposon-derived gene in the human genome.
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Saito M, Ladha A, Strecker J, Faure G, Neumann E, Altae-Tran H, Macrae RK, Zhang F. Dual modes of CRISPR-associated transposon homing. Cell 2021; 184:2441-2453.e18. [PMID: 33770501 PMCID: PMC8276595 DOI: 10.1016/j.cell.2021.03.006] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/25/2021] [Accepted: 03/02/2021] [Indexed: 12/23/2022]
Abstract
Tn7-like transposons have co-opted CRISPR systems, including class 1 type I-F, I-B, and class 2 type V-K. Intriguingly, although these CRISPR-associated transposases (CASTs) undergo robust CRISPR RNA (crRNA)-guided transposition, they are almost never found in sites targeted by the crRNAs encoded by the cognate CRISPR array. To understand this paradox, we investigated CAST V-K and I-B systems and found two distinct modes of transposition: (1) crRNA-guided transposition and (2) CRISPR array-independent homing. We show distinct CAST systems utilize different molecular mechanisms to target their homing site. Type V-K CAST systems use a short, delocalized crRNA for RNA-guided homing, whereas type I-B CAST systems, which contain two distinct target selector proteins, use TniQ for RNA-guided DNA transposition and TnsD for homing to an attachment site. These observations illuminate a key step in the life cycle of CAST systems and highlight the diversity of molecular mechanisms mediating transposon homing.
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Affiliation(s)
- Makoto Saito
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alim Ladha
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jonathan Strecker
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Guilhem Faure
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Edwin Neumann
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Han Altae-Tran
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Rhiannon K Macrae
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Feng Zhang
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; McGovern Institute for Brain Research at MIT, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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7
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Zhang Z, Wang H, Wang Y, Xi F, Wang H, Kohnen MV, Gao P, Wei W, Chen K, Liu X, Gao Y, Han X, Hu K, Zhang H, Zhu Q, Zheng Y, Liu B, Ahmad A, Hsu YH, Jacobsen SE, Gu L. Whole-genome characterization of chronological age-associated changes in methylome and circular RNAs in moso bamboo (Phyllostachys edulis) from vegetative to floral growth. Plant J 2021; 106:435-453. [PMID: 33506534 DOI: 10.1111/tpj.15174] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/30/2020] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
In mammals, DNA methylation is associated with aging. However, age-related DNA methylation changes during phase transitions largely remain unstudied in plants. Moso bamboo (Phyllostachys edulis) requires a very long time to transition from the vegetative to the floral phase. To comprehensively investigate the association of DNA methylation with aging, we present here single-base-resolution DNA methylation profiles using both high-throughput bisulfite sequencing and single-molecule nanopore-based DNA sequencing, covering the long period of vegetative growth and transition to flowering in moso bamboo. We discovered that CHH methylation gradually accumulates from vegetative to reproductive growth in a time-dependent fashion. Differentially methylated regions, correlating with chronological aging, occurred preferentially at both transcription start sites and transcription termination sites. Genes with CG methylation changes showed an enrichment of Gene Ontology (GO) categories in 'vegetative to reproductive phase transition of meristem'. Combining methylation data with mRNA sequencing revealed that DNA methylation in promoters, introns and exons may have different roles in regulating gene expression. Finally, circular RNA (circRNA) sequencing revealed that the flanking introns of circRNAs are hypermethylated and enriched in long terminal repeat (LTR) retrotransposons. Together, the observations in this study provide insights into the dynamic DNA methylation and circRNA landscapes, correlating with chronological age, which paves the way to study further the impact of epigenetic factors on flowering in moso bamboo.
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Affiliation(s)
- Zeyu Zhang
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Huihui Wang
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yongsheng Wang
- Basic Forestry and Proteomics Research Center, College of life science, Fuzhou, 350002, China
| | - Feihu Xi
- Basic Forestry and Proteomics Research Center, College of life science, Fuzhou, 350002, China
| | - Huiyuan Wang
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Markus V Kohnen
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Pengfei Gao
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Wentao Wei
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Kai Chen
- Basic Forestry and Proteomics Research Center, College of life science, Fuzhou, 350002, China
| | - Xuqing Liu
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yubang Gao
- Basic Forestry and Proteomics Research Center, College of life science, Fuzhou, 350002, China
| | - Ximei Han
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Kaiqiang Hu
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Hangxiao Zhang
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Qiang Zhu
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yushan Zheng
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Bo Liu
- College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Ayaz Ahmad
- Department of Biotechnology, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Yau-Heiu Hsu
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Steven E Jacobsen
- Department of Molecular, Cell & Developmental Biology, Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA
| | - Lianfeng Gu
- Basic Forestry and Proteomics Research Center, College of Forestry, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
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Lee YS, Maple R, Dürr J, Dawson A, Tamim S, Del Genio C, Papareddy R, Luo A, Lamb JC, Amantia S, Sylvester AW, Birchler JA, Meyers BC, Nodine MD, Rouster J, Gutierrez-Marcos J. A transposon surveillance mechanism that safeguards plant male fertility during stress. Nat Plants 2021; 7:34-41. [PMID: 33398155 DOI: 10.1038/s41477-020-00818-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 11/05/2020] [Indexed: 06/12/2023]
Abstract
Although plants are able to withstand a range of environmental conditions, spikes in ambient temperature can impact plant fertility causing reductions in seed yield and notable economic losses1,2. Therefore, understanding the precise molecular mechanisms that underpin plant fertility under environmental constraints is critical to safeguarding future food production3. Here, we identified two Argonaute-like proteins whose activities are required to sustain male fertility in maize plants under high temperatures. We found that MALE-ASSOCIATED ARGONAUTE-1 and -2 associate with temperature-induced phased secondary small RNAs in pre-meiotic anthers and are essential to controlling the activity of retrotransposons in male meiocyte initials. Biochemical and structural analyses revealed how male-associated Argonaute activity and its interaction with retrotransposon RNA targets is modulated through the dynamic phosphorylation of a set of highly conserved, surface-located serine residues. Our results demonstrate that an Argonaute-dependent, RNA-guided surveillance mechanism is critical in plants to sustain male fertility under environmentally constrained conditions, by controlling the mutagenic activity of transposons in male germ cells.
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Affiliation(s)
- Yang-Seok Lee
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Robert Maple
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Julius Dürr
- School of Life Sciences, University of Warwick, Coventry, UK
| | | | - Saleh Tamim
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, USA
| | - Charo Del Genio
- Centre for Fluid and Complex Systems, School of Computing, Electronics and Mathematics, Coventry University, Coventry, UK
| | - Ranjith Papareddy
- Division of Plant Sciences, University of Missouri, Columbia, MO, USA
| | - Anding Luo
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
| | - Jonathan C Lamb
- Division of Biological Sciences, University of Missouri, Columbia, MO, USA
- BayerCrop Science Division, St. Louis, MO, USA
| | - Stefano Amantia
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Anne W Sylvester
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
| | - James A Birchler
- Division of Biological Sciences, University of Missouri, Columbia, MO, USA
| | - Blake C Meyers
- Division of Plant Sciences, University of Missouri, Columbia, MO, USA
- Donald Danforth Plant Science Center, St. Louis, MO, USA
| | - Michael D Nodine
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Vienna, Austria
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MESH Headings
- Antigen Presentation/genetics
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/physiology
- Betacoronavirus/physiology
- COVID-19
- Cathepsins/antagonists & inhibitors
- Cathepsins/physiology
- Cell Line
- Coronavirus Infections/prevention & control
- Coronavirus Infections/virology
- DNA Transposable Elements/genetics
- DNA Transposable Elements/physiology
- Ebolavirus/physiology
- Gene Knockout Techniques
- Gene Silencing
- Genes, MHC Class II/genetics
- Genes, MHC Class II/physiology
- Hemorrhagic Fever, Ebola/prevention & control
- Hemorrhagic Fever, Ebola/virology
- Histocompatibility Antigens Class II/genetics
- Histocompatibility Antigens Class II/physiology
- Humans
- Pandemics/prevention & control
- Pneumonia, Viral/prevention & control
- Pneumonia, Viral/virology
- Protein Isoforms/genetics
- SARS-CoV-2
- Transcriptional Activation/genetics
- Virus Attachment
- Virus Replication/physiology
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10
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Kremer SC, Linquist S, Saylor B, Elliott TA, Gregory TR, Cottenie K. Transposable element persistence via potential genome-level ecosystem engineering. BMC Genomics 2020; 21:367. [PMID: 32429843 PMCID: PMC7236351 DOI: 10.1186/s12864-020-6763-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 04/30/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The nuclear genomes of eukaryotes vary enormously in size, with much of this variability attributable to differential accumulation of transposable elements (TEs). To date, the precise evolutionary and ecological conditions influencing TE accumulation remain poorly understood. Most previous attempts to identify these conditions have focused on evolutionary processes occurring at the host organism level, whereas we explore a TE ecology explanation. RESULTS As an alternative (or additional) hypothesis, we propose that ecological mechanisms occurring within the host cell may contribute to patterns of TE accumulation. To test this idea, we conducted a series of experiments using a simulated asexual TE/host system. Each experiment tracked the accumulation rate for a given type of TE within a particular host genome. TEs in this system had a net deleterious effect on host fitness, which did not change over the course of experiments. As one might expect, in the majority of experiments TEs were either purged from the genome or drove the host population to extinction. However, in an intriguing handful of cases, TEs co-existed with hosts and accumulated to very large numbers. This tended to occur when TEs achieved a stable density relative to non-TE sequences in the genome (as opposed to reaching any particular absolute number). In our model, the only way to maintain a stable density was for TEs to generate new, inactive copies at a rate that balanced with the production of active (replicating) copies. CONCLUSIONS From a TE ecology perspective, we suggest this could be interpreted as a case of ecosystem engineering within the genome, where TEs persist by creating their own "habitat".
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Affiliation(s)
- Stefan C Kremer
- School of Computer Science, University of Guelph, Guelph, ON, N1G 2W1, Canada.
| | - Stefan Linquist
- Department of Philosophy, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Brent Saylor
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Tyler A Elliott
- Centre for Biodiversity Genomics, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - T Ryan Gregory
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Karl Cottenie
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
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11
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Cavaliere V, Lattanzi G, Andrenacci D. Silencing of Euchromatic Transposable Elements as a Consequence of Nuclear Lamina Dysfunction. Cells 2020; 9:cells9030625. [PMID: 32151001 PMCID: PMC7140440 DOI: 10.3390/cells9030625] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/28/2020] [Accepted: 03/02/2020] [Indexed: 02/07/2023] Open
Abstract
Transposable elements (TEs) are mobile genomic sequences that are normally repressed to avoid proliferation and genome instability. Gene silencing mechanisms repress TEs by RNA degradation or heterochromatin formation. Heterochromatin maintenance is therefore important to keep TEs silent. Loss of heterochromatic domains has been linked to lamin mutations, which have also been associated with derepression of TEs. In fact, lamins are structural components of the nuclear lamina (NL), which is considered a pivotal structure in the maintenance of heterochromatin domains at the nuclear periphery in a silent state. Here, we show that a lethal phenotype associated with Lamin loss-of-function mutations is influenced by Drosophila gypsy retrotransposons located in euchromatic regions, suggesting that NL dysfunction has also effects on active TEs located in euchromatic loci. In fact, expression analysis of different long terminal repeat (LTR) retrotransposons and of one non-LTR retrotransposon located near active genes shows that Lamin inactivation determines the silencing of euchromatic TEs. Furthermore, we show that the silencing effect on euchromatic TEs spreads to the neighboring genomic regions, with a repressive effect on nearby genes. We propose that NL dysfunction may have opposed regulatory effects on TEs that depend on their localization in active or repressed regions of the genome.
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Affiliation(s)
- Valeria Cavaliere
- Dipartimento di Farmacia e Biotecnologie, Alma Mater Studiorum Università di Bologna, 40126 Bologna, Italy;
| | - Giovanna Lattanzi
- CNR Institute of Molecular Genetics “Luigi-Luca Cavalli-Sforza”, Unit of Bologna, 40136 Bologna, Italy;
- IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
| | - Davide Andrenacci
- CNR Institute of Molecular Genetics “Luigi-Luca Cavalli-Sforza”, Unit of Bologna, 40136 Bologna, Italy;
- IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
- Correspondence:
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12
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Montgomery SA, Tanizawa Y, Galik B, Wang N, Ito T, Mochizuki T, Akimcheva S, Bowman JL, Cognat V, Maréchal-Drouard L, Ekker H, Hong SF, Kohchi T, Lin SS, Liu LYD, Nakamura Y, Valeeva LR, Shakirov EV, Shippen DE, Wei WL, Yagura M, Yamaoka S, Yamato KT, Liu C, Berger F. Chromatin Organization in Early Land Plants Reveals an Ancestral Association between H3K27me3, Transposons, and Constitutive Heterochromatin. Curr Biol 2020; 30:573-588.e7. [PMID: 32004456 PMCID: PMC7209395 DOI: 10.1016/j.cub.2019.12.015] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/03/2019] [Accepted: 12/05/2019] [Indexed: 12/16/2022]
Abstract
Genome packaging by nucleosomes is a hallmark of eukaryotes. Histones and the pathways that deposit, remove, and read histone modifications are deeply conserved. Yet, we lack information regarding chromatin landscapes in extant representatives of ancestors of the main groups of eukaryotes, and our knowledge of the evolution of chromatin-related processes is limited. We used the bryophyte Marchantia polymorpha, which diverged from vascular plants circa 400 mya, to obtain a whole chromosome genome assembly and explore the chromatin landscape and three-dimensional genome organization in an early diverging land plant lineage. Based on genomic profiles of ten chromatin marks, we conclude that the relationship between active marks and gene expression is conserved across land plants. In contrast, we observed distinctive features of transposons and other repetitive sequences in Marchantia compared with flowering plants. Silenced transposons and repeats did not accumulate around centromeres. Although a large fraction of constitutive heterochromatin was marked by H3K9 methylation as in flowering plants, a significant proportion of transposons were marked by H3K27me3, which is otherwise dedicated to the transcriptional repression of protein-coding genes in flowering plants. Chromatin compartmentalization analyses of Hi-C data revealed that repressed B compartments were densely decorated with H3K27me3 but not H3K9 or DNA methylation as reported in flowering plants. We conclude that, in early plants, H3K27me3 played an essential role in heterochromatin function, suggesting an ancestral role of this mark in transposon silencing.
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Affiliation(s)
- Sean A Montgomery
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Dr. Bohr Gasse 3, 1030 Vienna, Austria
| | - Yasuhiro Tanizawa
- Department of Informatics, National Institute of Genetics, Research Organization of Information and Systems, 1111 Yata, Mishima, Japan
| | - Bence Galik
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Dr. Bohr Gasse 3, 1030 Vienna, Austria
| | - Nan Wang
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076 Tübingen, Germany
| | - Tasuku Ito
- John Innes Centre, Colney lane, Norwich NR4 7UH, UK
| | - Takako Mochizuki
- Department of Informatics, National Institute of Genetics, Research Organization of Information and Systems, 1111 Yata, Mishima, Japan
| | - Svetlana Akimcheva
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Dr. Bohr Gasse 3, 1030 Vienna, Austria
| | - John L Bowman
- School of Biological Sciences, Monash University, Melbourne, 3800 VIC, Australia
| | - Valérie Cognat
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France
| | - Laurence Maréchal-Drouard
- Institut de biologie moléculaire des plantes-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France
| | - Heinz Ekker
- Vienna BioCenter Core Facilities (VBCF), Next Generation Sequencing facility, Dr. Bohr Gasse 3, 1030 Vienna, Austria
| | - Syuan-Fei Hong
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan
| | - Takayuki Kohchi
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Shih-Shun Lin
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan
| | - Li-Yu Daisy Liu
- Department of Agronomy, National Taiwan University, Taipei 106, Taiwan
| | - Yasukazu Nakamura
- Department of Informatics, National Institute of Genetics, Research Organization of Information and Systems, 1111 Yata, Mishima, Japan
| | - Lia R Valeeva
- Institute of Fundamental Medicine and Biology, Kazan (Volga Region) Federal University, Kazan, Republic of Tatarstan 420008, Russia
| | - Eugene V Shakirov
- Institute of Fundamental Medicine and Biology, Kazan (Volga Region) Federal University, Kazan, Republic of Tatarstan 420008, Russia; Department of Biological Sciences, Marshall University, Huntington, WV 25701, USA
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843-2128, USA
| | - Wei-Lun Wei
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan
| | - Masaru Yagura
- Department of Informatics, National Institute of Genetics, Research Organization of Information and Systems, 1111 Yata, Mishima, Japan
| | - Shohei Yamaoka
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
| | - Katsuyuki T Yamato
- Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Wakayama 649-6493, Japan
| | - Chang Liu
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Auf der Morgenstelle 32, 72076 Tübingen, Germany.
| | - Frédéric Berger
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Dr. Bohr Gasse 3, 1030 Vienna, Austria.
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13
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Hu L, Li N, Zhang Z, Meng X, Dong Q, Xu C, Gong L, Liu B. CG hypomethylation leads to complex changes in DNA methylation and transpositional burst of diverse transposable elements in callus cultures of rice. Plant J 2020; 101:188-203. [PMID: 31529551 DOI: 10.1111/tpj.14531] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/01/2019] [Accepted: 09/05/2019] [Indexed: 06/10/2023]
Abstract
CG methylation (m CG) is essential for preserving genome stability in mammals, but this link remains obscure in plants. OsMET1-2, a major rice DNA methyltransferase, plays critical roles in maintaining m CG in rice. Null mutation of OsMET1-2 causes massive CG hypomethylation, rendering the mutant suitable to address the role of m CG in maintaining genome integrity in plants. Here, we analyzed m CG dynamics and genome stability in tissue cultures of OsMET1-2 homozygous (-/-) and heterozygous (+/-) mutants, and isogenic wild-type (WT). We found m CG levels in cultures of -/- were substantially lower than in those of WT and +/-, as expected. Unexpectedly, m CG levels in 1- and 3-year cultures of -/- were 77.6% and 48.7% higher, respectively, than in shoot, from which the cultures were initiated, suggesting substantial regain of m CG in -/- cultures, which contrasts to the general trend of m CG loss in all WT plant tissue cultures hitherto studied. Transpositional burst of diverse transposable elements (TEs) occurred only in -/- cultures, although no elevation of genome-wide mutation rate in the form of single nucleotide polymorphisms was detected. Altogether, our results establish an essential role of m CG in retaining TE immobility and hence genome stability in rice and likely in plants in general.
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Affiliation(s)
- Lanjuan Hu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
- College of Plant Sciences, Faculty of Agriculture, Jilin University, Changchun, 130062, China
| | - Ning Li
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Zhibin Zhang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Xinchao Meng
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Qianli Dong
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Chunming Xu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Lei Gong
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Bao Liu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
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14
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Kenchanmane Raju SK, Ritter EJ, Niederhuth CE. Establishment, maintenance, and biological roles of non-CG methylation in plants. Essays Biochem 2019; 63:743-755. [PMID: 31652316 PMCID: PMC6923318 DOI: 10.1042/ebc20190032] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/18/2019] [Accepted: 09/20/2019] [Indexed: 12/18/2022]
Abstract
Cytosine DNA methylation is prevalent throughout eukaryotes and prokaryotes. While most commonly thought of as being localized to dinucleotide CpG sites, non-CG sites can also be modified. Such non-CG methylation is widespread in plants, occurring at trinucleotide CHG and CHH (H = A, T, or C) sequence contexts. The prevalence of non-CG methylation in plants is due to the plant-specific CHROMOMETHYLASE (CMT) and RNA-directed DNA Methylation (RdDM) pathways. These pathways have evolved through multiple rounds of gene duplication and gene loss, generating epigenomic variation both within and between species. They regulate both transposable elements and genes, ensure genome integrity, and ultimately influence development and environmental responses. In these capacities, non-CG methylation influence and shape plant genomes.
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Affiliation(s)
| | | | - Chad E Niederhuth
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, U.S.A
- AgBioResearch, Michigan State University, East Lansing, MI 48824, U.S.A
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15
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Abstract
Transposon Tn7 is notable for the control it exercises over where transposition events are directed. One Tn7 integration pathways recognizes a highly conserved attachment (att) site in the chromosome, while a second pathway specifically recognizes mobile plasmids that facilitate transfer of the element to new hosts. In this review, I discuss newly discovered families of Tn7-like elements with different targeting pathways. Perhaps the most exciting examples are multiple instances where Tn7-like elements have repurposed CRISPR/Cas systems. In these cases, the CRISPR/Cas systems have lost their canonical defensive function to destroy incoming mobile elements; instead, the systems have been naturally adapted to use guide RNAs to specifically direct transposition into these mobile elements. The new families of Tn7-like elements also include a variety of novel att sites in bacterial chromosomes where genome islands can form. Interesting families have also been revealed where proteins described in the prototypic Tn7 element are fused or otherwise repurposed for the new dual activities. This expanded understanding of Tn7-like elements broadens our view of how genetic systems are repurposed and provides potentially exciting new tools for genome modification and genomics. Future opportunities and challenges to understanding the impact of the new families of Tn7-like elements are discussed.
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Affiliation(s)
- Joseph E Peters
- Department of Microbiology, Cornell University, 175a Wing Hall, Ithaca, NY, 14853, USA
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16
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Diezma‐Navas L, Pérez‐González A, Artaza H, Alonso L, Caro E, Llave C, Ruiz‐Ferrer V. Crosstalk between epigenetic silencing and infection by tobacco rattle virus in Arabidopsis. Mol Plant Pathol 2019; 20:1439-1452. [PMID: 31274236 PMCID: PMC6792132 DOI: 10.1111/mpp.12850] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
DNA methylation is an important epigenetic mechanism for controlling innate immunity against microbial pathogens in plants. Little is known, however, about the manner in which viral infections interact with DNA methylation pathways. Here we investigate the crosstalk between epigenetic silencing and viral infections in Arabidopsis inflorescences. We found that tobacco rattle virus (TRV) causes changes in the expression of key transcriptional gene silencing factors with RNA-directed DNA methylation activities that coincide with changes in methylation at the whole genome level. Viral susceptibility/resistance was altered in DNA (de)methylation-deficient mutants, suggesting that DNA methylation is an important regulatory system controlling TRV proliferation. We further show that several transposable elements (TEs) underwent transcriptional activation during TRV infection, and that TE regulation likely involved both DNA methylation-dependent and -independent mechanisms. We identified a cluster of disease resistance genes regulated by DNA methylation in infected plants that were enriched for TEs in their promoters. Interestingly, TEs and nearby resistance genes were co-regulated in TRV-infected DNA (de)methylation mutants. Our study shows that DNA methylation contributes to modulate the outcome of viral infections in Arabidopsis, and opens up new possibilities for exploring the role of TE regulation in antiviral defence.
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Affiliation(s)
- Laura Diezma‐Navas
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones BiológicasCSICRamiro de Maeztu 9MadridSpain
- Doctorado en Biotecnología y Recursos Genéticos de Plantas y Microorganismos AsociadosETSI Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid28040MadridSpain
| | - Ana Pérez‐González
- Centro de Biotecnología y Genómica de PlantasUniversidad Politécnica de Madrid (UPM)Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)Campus de Montegancedo UPM28223Pozuelo de Alarcón, MadridSpain
| | - Haydeé Artaza
- Bionformatic and Statistic Service, Centro de Investigaciones BiológicasCSICRamiro de Maeztu 928040MadridSpain
- Present address:
Department of Clinical ScienceUniversity of Bergen5020BergenNorway
| | - Lola Alonso
- Bionformatic and Statistic Service, Centro de Investigaciones BiológicasCSICRamiro de Maeztu 928040MadridSpain
- Present address:
Genetic and Molecular Epidemiology Group, Spanish National Cancer Research Center (CNIO)MadridSpain
| | - Elena Caro
- Centro de Biotecnología y Genómica de PlantasUniversidad Politécnica de Madrid (UPM)Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)Campus de Montegancedo UPM28223Pozuelo de Alarcón, MadridSpain
| | - César Llave
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones BiológicasCSICRamiro de Maeztu 9MadridSpain
| | - Virginia Ruiz‐Ferrer
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones BiológicasCSICRamiro de Maeztu 9MadridSpain
- Present address:
Department of Plant Physiology, Plant Biotechnology and Molecular Biology Group. Environmental Sciences and Biochemistry SchoolCastilla‐La Mancha UniversityToledoSpain
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17
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Zheng X, Zhu K, Sun Q, Zhang W, Wang X, Cao H, Tan M, Xie Z, Zeng Y, Ye J, Chai L, Xu Q, Pan Z, Xiao S, Fraser PD, Deng X. Natural Variation in CCD4 Promoter Underpins Species-Specific Evolution of Red Coloration in Citrus Peel. Mol Plant 2019; 12:1294-1307. [PMID: 31102783 DOI: 10.1016/j.molp.2019.04.014] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 03/26/2019] [Accepted: 04/29/2019] [Indexed: 05/06/2023]
Abstract
Carotenoids and apocarotenoids act as phytohormones and volatile precursors that influence plant development and confer aesthetic and nutritional value critical to consumer preference. Citrus fruits display considerable natural variation in carotenoid and apocarotenoid pigments. In this study, using an integrated genetic approach we revealed that a 5' cis-regulatory change at CCD4b encoding CAROTENOID CLEAVAGE DIOXYGENASE 4b is a major genetic determinant of natural variation in C30 apocarotenoids responsible for red coloration of citrus peel. Functional analyses demonstrated that in addition the known role in synthesizing β-citraurin, CCD4b is also responsible for the production of another important C30 apocarotenoid pigment, β-citraurinene. Furthermore, analyses of the CCD4b promoter and transcripts from various citrus germplasm accessions established a tight correlation between the presence of a putative 5' cis-regulatory enhancer within an MITE transposon and the enhanced allelic expression of CCD4b in C30 apocarotenoid-rich red-peeled accessions. Phylogenetic analysis provided further evidence that functional diversification of CCD4b and naturally occurring variation of the CCD4b promoter resulted in the stepwise evolution of red peels in mandarins and their hybrids. Taken together, our findings provide new insights into the genetic and evolutionary basis of apocarotenoid diversity in plants, and would facilitate breeding efforts that aim to improve the nutritional and aesthetic value of citrus and perhaps other fruit crops.
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Affiliation(s)
- Xiongjie Zheng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Kaijie Zhu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Quan Sun
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Weiyi Zhang
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Xia Wang
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Hongbo Cao
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Meilian Tan
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Zongzhou Xie
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Yunliu Zeng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Junli Ye
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Lijun Chai
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Qiang Xu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China
| | - Zhiyong Pan
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China.
| | - Shunyuan Xiao
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China; Department of Plant Science and Landscape Architecture, Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, MD, USA
| | - Paul D Fraser
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK
| | - Xiuxin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, China.
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18
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Abstract
Transposable elements (TEs) are mobile DNA sequences that colonize genomes and threaten genome integrity. As a result, several mechanisms appear to have emerged during eukaryotic evolution to suppress TE activity. However, TEs are ubiquitous and account for a prominent fraction of most eukaryotic genomes. We argue that the evolutionary success of TEs cannot be explained solely by evasion from host control mechanisms. Rather, some TEs have evolved commensal and even mutualistic strategies that mitigate the cost of their propagation. These coevolutionary processes promote the emergence of complex cellular activities, which in turn pave the way for cooption of TE sequences for organismal function.
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Affiliation(s)
- Rachel L Cosby
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
| | - Ni-Chen Chang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
| | - Cédric Feschotte
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
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19
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Li S, Jia S, Hou L, Nguyen H, Sato S, Holding D, Cahoon E, Zhang C, Clemente T, Yu B. Mapping of transgenic alleles in soybean using a nanopore-based sequencing strategy. J Exp Bot 2019; 70:3825-3833. [PMID: 31037287 PMCID: PMC6685662 DOI: 10.1093/jxb/erz202] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 04/15/2019] [Indexed: 05/23/2023]
Abstract
Transgenic technology was developed to introduce transgenes into various organisms to validate gene function and add genetic variations >40 years ago. However, the identification of the transgene insertion position is still challenging in organisms with complex genomes. Here, we report a nanopore-based method to map the insertion position of a Ds transposable element originating in maize in the soybean genome. In this method, an oligo probe is used to capture the DNA fragments containing the Ds element from pooled DNA samples of transgenic soybean plants. The Ds element-enriched DNAs are then sequenced using the MinION-based platform of Nanopore. This method allowed us to rapidly map the Ds insertion positions in 51 transgenic soybean lines through a single sequencing run. This strategy is high throughput, convenient, reliable, and cost-efficient. The transgenic allele mapping protocol can be easily translated to other eukaryotes with complex genomes.
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Affiliation(s)
- Shengjun Li
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
- Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Shangang Jia
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Lili Hou
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Hanh Nguyen
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Shirley Sato
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - David Holding
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Edgar Cahoon
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Chi Zhang
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Tom Clemente
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Bin Yu
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA
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20
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Jang J, Sakai Y, Senoo K, Ishii S. Potentially Mobile Denitrification Genes Identified in Azospirillum sp. Strain TSH58. Appl Environ Microbiol 2019; 85:e02474-18. [PMID: 30413471 PMCID: PMC6328785 DOI: 10.1128/aem.02474-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 11/05/2018] [Indexed: 11/20/2022] Open
Abstract
Denitrification ability is sporadically distributed among diverse bacteria, archaea, and fungi. In addition, disagreement has been found between denitrification gene phylogenies and the 16S rRNA gene phylogeny. These facts have suggested potential occurrences of horizontal gene transfer (HGT) for the denitrification genes. However, evidence of HGT has not been clearly presented thus far. In this study, we identified the sequences and the localization of the nitrite reductase genes in the genomes of 41 denitrifying Azospirillum sp. strains and searched for mobile genetic elements that contain denitrification genes. All Azospirillum sp. strains examined in this study possessed multiple replicons (4 to 11 replicons), with their sizes ranging from 7 to 1,031 kbp. Among those, the nitrite reductase gene nirK was located on large replicons (549 to 941 kbp). Genome sequencing showed that Azospirillum strains that had similar nirK sequences also shared similar nir-nor gene arrangements, especially between the TSH58, Sp7T, and Sp245 strains. In addition to the high similarity between nir-nor gene clusters among the three Azospirillum strains, a composite transposon structure was identified in the genome of strain TSH58, which contains the nir-nor gene cluster and the novel IS6 family insertion sequences (ISAz581 and ISAz582). The nirK gene within the composite transposon system was actively transcribed under denitrification-inducing conditions. Although not experimentally verified in this study, the composite transposon system containing the nir-nor gene cluster could be transferred to other cells if it is moved to a prophage region and the phage becomes activated and released outside the cells. Taken together, strain TSH58 most likely acquired its denitrification ability by HGT from closely related Azospirillum sp. denitrifiers.IMPORTANCE The evolutionary history of denitrification is complex. While the occurrence of horizontal gene transfer has been suggested for denitrification genes, most studies report circumstantial evidences, such as disagreement between denitrification gene phylogenies and the 16S rRNA gene phylogeny. Based on the comparative genome analyses of Azospirillum sp. denitrifiers, we identified denitrification genes, including nirK and norCBQD, located on a mobile genetic element in the genome of Azospirillum sp. strain TSH58. The nirK was actively transcribed under denitrification-inducing conditions. Since this gene was the sole nitrite reductase gene in strain TSH58, this strain most likely benefitted by acquiring denitrification genes via horizontal gene transfer. This finding will significantly advance our scientific knowledge regarding the ecology and evolution of denitrification.
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Affiliation(s)
- Jeonghwan Jang
- BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
| | - Yoriko Sakai
- Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
| | - Keishi Senoo
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan
| | - Satoshi Ishii
- BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
- Department of Soil, Water, and Climate, University of Minnesota, St. Paul, Minnesota, USA
- Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, Minnesota, USA
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Kelleher ES, Jaweria J, Akoma U, Ortega L, Tang W. QTL mapping of natural variation reveals that the developmental regulator bruno reduces tolerance to P-element transposition in the Drosophila female germline. PLoS Biol 2018; 16:e2006040. [PMID: 30376574 PMCID: PMC6207299 DOI: 10.1371/journal.pbio.2006040] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 09/26/2018] [Indexed: 12/15/2022] Open
Abstract
Transposable elements (TEs) are obligate genetic parasites that propagate in host genomes by replicating in germline nuclei, thereby ensuring transmission to offspring. This selfish replication not only produces deleterious mutations—in extreme cases, TE mobilization induces genotoxic stress that prohibits the production of viable gametes. Host genomes could reduce these fitness effects in two ways: resistance and tolerance. Resistance to TE propagation is enacted by germline-specific small-RNA-mediated silencing pathways, such as the Piwi-interacting RNA (piRNA) pathway, and is studied extensively. However, it remains entirely unknown whether host genomes may also evolve tolerance by desensitizing gametogenesis to the harmful effects of TEs. In part, the absence of research on tolerance reflects a lack of opportunity, as small-RNA-mediated silencing evolves rapidly after a new TE invades, thereby masking existing variation in tolerance. We have exploited the recent historical invasion of the Drosophila melanogaster genome by P-element DNA transposons in order to study tolerance of TE activity. In the absence of piRNA-mediated silencing, the genotoxic stress imposed by P-elements disrupts oogenesis and, in extreme cases, leads to atrophied ovaries that completely lack germline cells. By performing quantitative trait locus (QTL) mapping on a panel of recombinant inbred lines (RILs) that lack piRNA-mediated silencing of P-elements, we uncovered multiple QTL that are associated with differences in tolerance of oogenesis to P-element transposition. We localized the most significant QTL to a small 230-kb euchromatic region, with the logarithm of the odds (LOD) peak occurring in the bruno locus, which codes for a critical and well-studied developmental regulator of oogenesis. Genetic, cytological, and expression analyses suggest that bruno dosage modulates germline stem cell (GSC) loss in the presence of P-element activity. Our observations reveal segregating variation in TE tolerance for the first time, and implicate gametogenic regulators as a source of tolerant variants in natural populations. Transposable elements (TEs), or “jumping genes,” are mobile fragments of selfish DNA that leave deleterious mutations and DNA damage in their wake as they spread through host genomes. Their harmful effects are known to select for resistance by the host, in which the propagation of TEs is regulated and reduced. Here, we study for the first time whether host cells might also exhibit tolerance to TEs, by reducing their harmful effects without directly controlling their movement. By taking advantage of a panel of wild-type Drosophila melanogaster that lack resistance to P-element DNA transposons, we identified a small region of the genome that influences tolerance of P-element activity. We further demonstrate that a gene within that region, bruno, strongly influences the negative effects of P-element mobilization on the fly. When bruno dosage is reduced, the fertility of females carrying mobile P-elements is enhanced. The bruno locus encodes a protein with no known role in TE regulation but multiple well-characterized functions in oogenesis. We propose that bruno function reduces tolerance of the developing oocyte to DNA damage that is caused by P-elements.
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Affiliation(s)
- Erin S. Kelleher
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United State of America
- * E-mail:
| | - Jaweria Jaweria
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United State of America
| | - Uchechukwu Akoma
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United State of America
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lily Ortega
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United State of America
| | - Wenpei Tang
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United State of America
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Shimada T, Endo T, Fujii H, Nakano M, Sugiyama A, Daido G, Ohta S, Yoshioka T, Omura M. MITE insertion-dependent expression of CitRKD1 with a RWP-RK domain regulates somatic embryogenesis in citrus nucellar tissues. BMC Plant Biol 2018; 18:166. [PMID: 30103701 PMCID: PMC6090715 DOI: 10.1186/s12870-018-1369-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/24/2018] [Indexed: 05/24/2023]
Abstract
BACKGROUND Somatic embryogenesis in nucellar tissues is widely recognized to induce polyembryony in major citrus varieties such as sweet oranges, satsuma mandarins and lemons. This capability for apomixis is attractive in agricultural production systems using hybrid seeds, and many studies have been performed to elucidate the molecular mechanisms of various types of apomixis. To identify the gene responsible for somatic embryogenesis in citrus, a custom oligo-DNA microarray including predicted genes in the citrus polyembryonic locus was used to compare the expression profiles in reproductive tissues between monoembryonic and polyembryonic varieties. The full length of CitRKD1, which was identified as a candidate gene responsible for citrus somatic embryogenesis, was isolated from satsuma mandarin and its molecular function was investigated using transgenic 'Hamlin' sweet orange by antisense-overexpression. RESULTS The candidate gene CitRKD1, predominantly transcribed in reproductive tissues of polyembryonic varieties, is a member of the plant RWP-RK domain-containing protein. CitRKD1 of satsuma mandarin comprised two alleles (CitRKD1-mg1 and CitRKD1-mg2) at the polyembryonic locus controlling embryonic type (mono/polyembryony) that were structurally divided into two types with or without a miniature inverted-repeat transposable element (MITE)-like insertion in the upstream region. CitRKD1-mg2 with the MITE insertion was the predominant transcript in flowers and young fruits where somatic embryogenesis of nucellar cells occurred. Loss of CitRKD1 function by antisense-overexpression abolished somatic embryogenesis in transgenic sweet orange and the transgenic T1 plants were confirmed to derive from zygotic embryos produced by self-pollination by DNA diagnosis. Genotyping PCR analysis of 95 citrus traditional and breeding varieties revealed that the CitRKD1 allele with the MITE insertion (polyembryonic allele) was dominant and major citrus varieties with the polyembryonic allele produced polyembryonic seeds. CONCLUSION CitRKD1 at the polyembryonic locus plays a principal role in regulating citrus somatic embryogenesis. CitRKD1 comprised multiple alleles that were divided into two types, polyembryonic alleles with a MITE insertion in the upstream region and monoembryonic alleles without it. CitRKD1 was transcribed in reproductive tissues of polyembryonic varieties with the polyembryonic allele. The MITE insertion in the upstream region of CitRKD1 might be involved in regulating the transcription of CitRKD1.
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Affiliation(s)
- Takehiko Shimada
- National Agriculture and Food Research Organization, Institute of Fruit and Tea Tree Science, Shimizu, Shizuoka, 424-0292 Japan
| | - Tomoko Endo
- National Agriculture and Food Research Organization, Institute of Fruit and Tea Tree Science, Shimizu, Shizuoka, 424-0292 Japan
| | - Hiroshi Fujii
- National Agriculture and Food Research Organization, Institute of Fruit and Tea Tree Science, Shimizu, Shizuoka, 424-0292 Japan
| | - Michiharu Nakano
- Faculty of Agriculture, Shizuoka University, Suruga, Shizuoka, 422-8529 Japan
| | - Aiko Sugiyama
- Faculty of Agriculture, Shizuoka University, Suruga, Shizuoka, 422-8529 Japan
| | - Genya Daido
- Faculty of Agriculture, Shizuoka University, Suruga, Shizuoka, 422-8529 Japan
| | - Satoshi Ohta
- National Agriculture and Food Research Organization, Institute of Fruit and Tea Tree Science, Shimizu, Shizuoka, 424-0292 Japan
| | - Terutaka Yoshioka
- National Agriculture and Food Research Organization, Institute of Fruit and Tea Tree Science, Shimizu, Shizuoka, 424-0292 Japan
| | - Mitsuo Omura
- Faculty of Agriculture, Shizuoka University, Suruga, Shizuoka, 422-8529 Japan
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23
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Lewis SH, Quarles KA, Yang Y, Tanguy M, Frézal L, Smith SA, Sharma PP, Cordaux R, Gilbert C, Giraud I, Collins DH, Zamore PD, Miska EA, Sarkies P, Jiggins FM. Pan-arthropod analysis reveals somatic piRNAs as an ancestral defence against transposable elements. Nat Ecol Evol 2018; 2:174-181. [PMID: 29203920 PMCID: PMC5732027 DOI: 10.1038/s41559-017-0403-4] [Citation(s) in RCA: 169] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 11/02/2017] [Indexed: 02/02/2023]
Abstract
In animals, small RNA molecules termed PIWI-interacting RNAs (piRNAs) silence transposable elements (TEs), protecting the germline from genomic instability and mutation. piRNAs have been detected in the soma in a few animals, but these are believed to be specific adaptations of individual species. Here, we report that somatic piRNAs were probably present in the ancestral arthropod more than 500 million years ago. Analysis of 20 species across the arthropod phylum suggests that somatic piRNAs targeting TEs and messenger RNAs are common among arthropods. The presence of an RNA-dependent RNA polymerase in chelicerates (horseshoe crabs, spiders and scorpions) suggests that arthropods originally used a plant-like RNA interference mechanism to silence TEs. Our results call into question the view that the ancestral role of the piRNA pathway was to protect the germline and demonstrate that small RNA silencing pathways have been repurposed for both somatic and germline functions throughout arthropod evolution.
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Affiliation(s)
- Samuel H Lewis
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK.
- Medical Research Council London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK.
- Institute for Clinical Sciences, Imperial College London, Du Cane Road, London, W12 0NN, UK.
| | - Kaycee A Quarles
- Howard Hughes Medical Institute, RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Yujing Yang
- Howard Hughes Medical Institute, RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Melanie Tanguy
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- Wellcome Trust/Cancer Research UK Gurdon Institute, Cambridge, CB2 1QN, UK
| | - Lise Frézal
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- Wellcome Trust/Cancer Research UK Gurdon Institute, Cambridge, CB2 1QN, UK
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Inserm, Ecole Normale Supérieure, Paris Sciences & Lettres Research University, 75005, Paris, France
| | - Stephen A Smith
- Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, 205 Duck Pond Drive, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Prashant P Sharma
- Department of Zoology, University of Wisconsin-Madison, 352 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Richard Cordaux
- Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpain, TSA 51106, 86073, Poitiers Cedex 9, France
| | - Clément Gilbert
- Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpain, TSA 51106, 86073, Poitiers Cedex 9, France
- Laboratoire Evolution, Génomes, Comportement, Écologie, Unité Mixte de Recherche 9191 Centre National de la Recherche Scientifique and Unité Mixte de Recherche 247 Institut de Recherche pour le Développement, Université Paris-Sud, 91198, Gif-sur-Yvette, France
| | - Isabelle Giraud
- Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpain, TSA 51106, 86073, Poitiers Cedex 9, France
| | - David H Collins
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Phillip D Zamore
- Howard Hughes Medical Institute, RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Eric A Miska
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- Wellcome Trust/Cancer Research UK Gurdon Institute, Cambridge, CB2 1QN, UK
| | - Peter Sarkies
- Medical Research Council London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK
- Institute for Clinical Sciences, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK.
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24
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Lin JY, Le BH, Chen M, Henry KF, Hur J, Hsieh TF, Chen PY, Pelletier JM, Pellegrini M, Fischer RL, Harada JJ, Goldberg RB. Similarity between soybean and Arabidopsis seed methylomes and loss of non-CG methylation does not affect seed development. Proc Natl Acad Sci U S A 2017; 114:E9730-E9739. [PMID: 29078418 PMCID: PMC5692608 DOI: 10.1073/pnas.1716758114] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We profiled soybean and Arabidopsis methylomes from the globular stage through dormancy and germination to understand the role of methylation in seed formation. CHH methylation increases significantly during development throughout the entire seed, targets primarily transposable elements (TEs), is maintained during endoreduplication, and drops precipitously within the germinating seedling. By contrast, no significant global changes in CG- and CHG-context methylation occur during the same developmental period. An Arabidopsis ddcc mutant lacking CHH and CHG methylation does not affect seed development, germination, or major patterns of gene expression, implying that CHH and CHG methylation does not play a significant role in seed development or in regulating seed gene activity. By contrast, over 100 TEs are transcriptionally de-repressed in ddcc seeds, suggesting that the increase in CHH-context methylation may be a failsafe mechanism to reinforce transposon silencing. Many genes encoding important classes of seed proteins, such as storage proteins, oil biosynthesis enzymes, and transcription factors, reside in genomic regions devoid of methylation at any stage of seed development. Many other genes in these classes have similar methylation patterns, whether the genes are active or repressed. Our results suggest that methylation does not play a significant role in regulating large numbers of genes important for programming seed development in both soybean and Arabidopsis. We conclude that understanding the mechanisms controlling seed development will require determining how cis-regulatory elements and their cognate transcription factors are organized in genetic regulatory networks.
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Affiliation(s)
- Jer-Young Lin
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Brandon H Le
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Min Chen
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Kelli F Henry
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Jungim Hur
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Tzung-Fu Hsieh
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
| | - Pao-Yang Chen
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Julie M Pelletier
- Section of Plant Biology, Division of Biological Sciences, University of California, Davis, CA 95616
| | - Matteo Pellegrini
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Robert L Fischer
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
| | - John J Harada
- Section of Plant Biology, Division of Biological Sciences, University of California, Davis, CA 95616
| | - Robert B Goldberg
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095;
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Simonti CN, Pavličev M, Capra JA. Transposable Element Exaptation into Regulatory Regions Is Rare, Influenced by Evolutionary Age, and Subject to Pleiotropic Constraints. Mol Biol Evol 2017; 34:2856-2869. [PMID: 28961735 PMCID: PMC5850124 DOI: 10.1093/molbev/msx219] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Transposable element (TE)-derived sequences make up approximately half of most mammalian genomes, and many TEs have been co-opted into gene regulatory elements. However, we lack a comprehensive tissue- and genome-wide understanding of how and when TEs gain regulatory activity in their hosts. We evaluated the prevalence of TE-derived DNA in enhancers and promoters across hundreds of human and mouse cell lines and primary tissues. Promoters are significantly depleted of TEs in all tissues compared with their overall prevalence in the genome (P < 0.001); enhancers are also depleted of TEs, though not as strongly as promoters. The degree of enhancer depletion also varies across contexts (1.5-3×), with reproductive and immune cells showing the highest levels of TE regulatory activity in humans. Overall, in spite of the regulatory potential of many TE sequences, they are significantly less active in gene regulation than expected from their prevalence. TE age is predictive of the likelihood of enhancer activity; TEs originating before the divergence of amniotes are 9.2 times more likely to have enhancer activity than TEs that integrated in great apes. Context-specific enhancers are more likely to be TE-derived than enhancers active in multiple tissues, and young TEs are more likely to overlap context-specific enhancers than old TEs (86% vs. 47%). Once TEs obtain enhancer activity in the host, they have similar functional dynamics to one another and non-TE-derived enhancers, likely driven by pleiotropic constraints. However, a few TE families, most notably endogenous retroviruses, have greater regulatory potential. Our observations suggest a model of regulatory co-option in which TE-derived sequences are initially repressed, after which a small fraction obtains context-specific enhancer activity, with further gains subject to pleiotropic constraints.
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Affiliation(s)
| | - Mihaela Pavličev
- Center for Prevention of Preterm Birth, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH
| | - John A. Capra
- Vanderbilt Genetics Institute, Vanderbilt University, Nashville, TN
- Department of Biological Sciences, Vanderbilt University, Nashville, TN
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Domb K, Keidar D, Yaakov B, Khasdan V, Kashkush K. Transposable elements generate population-specific insertional patterns and allelic variation in genes of wild emmer wheat (Triticum turgidum ssp. dicoccoides). BMC Plant Biol 2017; 17:175. [PMID: 29078757 PMCID: PMC5659041 DOI: 10.1186/s12870-017-1134-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 10/17/2017] [Indexed: 05/02/2023]
Abstract
BACKGROUND Natural populations of the tetraploid wild emmer wheat (genome AABB) were previously shown to demonstrate eco-geographically structured genetic and epigenetic diversity. Transposable elements (TEs) might make up a significant part of the genetic and epigenetic variation between individuals and populations because they comprise over 80% of the wild emmer wheat genome. In this study, we performed detailed analyses to assess the dynamics of transposable elements in 50 accessions of wild emmer wheat collected from 5 geographically isolated sites. The analyses included: the copy number variation of TEs among accessions in the five populations, population-unique insertional patterns, and the impact of population-unique/specific TE insertions on structure and expression of genes. RESULTS We assessed the copy numbers of 12 TE families using real-time quantitative PCR, and found significant copy number variation (CNV) in the 50 wild emmer wheat accessions, in a population-specific manner. In some cases, the CNV difference reached up to 6-fold. However, the CNV was TE-specific, namely some TE families showed higher copy numbers in one or more populations, and other TE families showed lower copy numbers in the same population(s). Furthermore, we assessed the insertional patterns of 6 TE families using transposon display (TD), and observed significant population-specific insertional patterns. The polymorphism levels of TE-insertional patterns reached 92% among all wild emmer wheat accessions, in some cases. In addition, we observed population-specific/unique TE insertions, some of which were located within or close to protein-coding genes, creating allelic variations in a population-specific manner. We also showed that those genes are differentially expressed in wild emmer wheat. CONCLUSIONS For the first time, this study shows that TEs proliferate in wild emmer wheat in a population-specific manner, creating new alleles of genes, which contribute to the divergent evolution of homeologous genes from the A and B subgenomes.
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Affiliation(s)
- Katherine Domb
- Department of Life Sciences, Ben-Gurion University, 84105 Beer-Sheva, Israel
| | - Danielle Keidar
- Department of Life Sciences, Ben-Gurion University, 84105 Beer-Sheva, Israel
| | - Beery Yaakov
- Department of Life Sciences, Ben-Gurion University, 84105 Beer-Sheva, Israel
| | - Vadim Khasdan
- Department of Life Sciences, Ben-Gurion University, 84105 Beer-Sheva, Israel
| | - Khalil Kashkush
- Department of Life Sciences, Ben-Gurion University, 84105 Beer-Sheva, Israel
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27
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Abstract
A survey of bacterial and archaeal genomes shows that many Tn7-like transposons contain minimal type I-F CRISPR-Cas systems that consist of fused cas8f and cas5f, cas7f, and cas6f genes and a short CRISPR array. Several small groups of Tn7-like transposons encompass similarly truncated type I-B CRISPR-Cas. This minimal gene complement of the transposon-associated CRISPR-Cas systems implies that they are competent for pre-CRISPR RNA (precrRNA) processing yielding mature crRNAs and target binding but not target cleavage that is required for interference. Phylogenetic analysis demonstrates that evolution of the CRISPR-Cas-containing transposons included a single, ancestral capture of a type I-F locus and two independent instances of type I-B loci capture. We show that the transposon-associated CRISPR arrays contain spacers homologous to plasmid and temperate phage sequences and, in some cases, chromosomal sequences adjacent to the transposon. We hypothesize that the transposon-encoded CRISPR-Cas systems generate displacement (R-loops) in the cognate DNA sites, targeting the transposon to these sites and thus facilitating their spread via plasmids and phages. These findings suggest the existence of RNA-guided transposition and fit the guns-for-hire concept whereby mobile genetic elements capture host defense systems and repurpose them for different stages in the life cycle of the element.
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Affiliation(s)
- Joseph E Peters
- Department of Microbiology, Cornell University, Ithaca, NY 14853;
| | - Kira S Makarova
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894
| | - Sergey Shmakov
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894
- Skolkovo Institute of Science and Technology, Skolkovo, 143025, Russia
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894;
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28
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Delavat F, Miyazaki R, Carraro N, Pradervand N, van der Meer JR. The hidden life of integrative and conjugative elements. FEMS Microbiol Rev 2017; 41:512-537. [PMID: 28369623 PMCID: PMC5812530 DOI: 10.1093/femsre/fux008] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 02/20/2017] [Indexed: 01/01/2023] Open
Abstract
Integrative and conjugative elements (ICEs) are widespread mobile DNA that transmit both vertically, in a host-integrated state, and horizontally, through excision and transfer to new recipients. Different families of ICEs have been discovered with more or less restricted host ranges, which operate by similar mechanisms but differ in regulatory networks, evolutionary origin and the types of variable genes they contribute to the host. Based on reviewing recent experimental data, we propose a general model of ICE life style that explains the transition between vertical and horizontal transmission as a result of a bistable decision in the ICE-host partnership. In the large majority of cells, the ICE remains silent and integrated, but hidden at low to very low frequencies in the population specialized host cells appear in which the ICE starts its process of horizontal transmission. This bistable process leads to host cell differentiation, ICE excision and transfer, when suitable recipients are present. The ratio of ICE bistability (i.e. ratio of horizontal to vertical transmission) is the outcome of a balance between fitness costs imposed by the ICE horizontal transmission process on the host cell, and selection for ICE distribution (i.e. ICE 'fitness'). From this emerges a picture of ICEs as elements that have adapted to a mostly confined life style within their host, but with a very effective and dynamic transfer from a subpopulation of dedicated cells.
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Affiliation(s)
- François Delavat
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne Switzerland
| | - Ryo Miyazaki
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki 305-8566, Japan
| | - Nicolas Carraro
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne Switzerland
| | - Nicolas Pradervand
- Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne Switzerland
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29
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Zakrzewski F, Schmidt M, Van Lijsebettens M, Schmidt T. DNA methylation of retrotransposons, DNA transposons and genes in sugar beet (Beta vulgaris L.). Plant J 2017; 90:1156-1175. [PMID: 28257158 DOI: 10.1111/tpj.13526] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 02/08/2017] [Accepted: 02/09/2017] [Indexed: 05/13/2023]
Abstract
The methylation of cytosines shapes the epigenetic landscape of plant genomes, coordinates transgenerational epigenetic inheritance, represses the activity of transposable elements (TEs), affects gene expression and, hence, can influence the phenotype. Sugar beet (Beta vulgaris ssp. vulgaris), an important crop that accounts for 30% of worldwide sugar needs, has a relatively small genome size (758 Mbp) consisting of approximately 485 Mbp repetitive DNA (64%), in particular satellite DNA, retrotransposons and DNA transposons. Genome-wide cytosine methylation in the sugar beet genome was studied in leaves and leaf-derived callus with a focus on repetitive sequences, including retrotransposons and DNA transposons, the major groups of repetitive DNA sequences, and compared with gene methylation. Genes showed a specific methylation pattern for CG, CHG (H = A, C, and T) and CHH sites, whereas the TE pattern differed, depending on the TE class (class 1, retrotransposons and class 2, DNA transposons). Along genes and TEs, CG and CHG methylation was higher than that of adjacent genomic regions. In contrast to the relatively low CHH methylation in retrotransposons and genes, the level of CHH methylation in DNA transposons was strongly increased, pointing to a functional role of asymmetric methylation in DNA transposon silencing. Comparison of genome-wide DNA methylation between sugar beet leaves and callus revealed a differential methylation upon tissue culture. Potential epialleles were hypomethylated (lower methylation) at CG and CHG sites in retrotransposons and genes and hypermethylated (higher methylation) at CHH sites in DNA transposons of callus when compared with leaves.
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Affiliation(s)
- Falk Zakrzewski
- Department of Biology, Technische Universität Dresden, 01062, Dresden, Germany
| | - Martin Schmidt
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium
- VIB Center for Plant Systems Biology, 9052, Ghent, Belgium
| | - Mieke Van Lijsebettens
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium
- VIB Center for Plant Systems Biology, 9052, Ghent, Belgium
| | - Thomas Schmidt
- Department of Biology, Technische Universität Dresden, 01062, Dresden, Germany
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30
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Mustafin RN, Khusnutdinova EK. [The role of interactions of transposons with epigenetic factors in the aging process]. Adv Gerontol 2017; 30:516-528. [PMID: 28968025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The review considers modern theories of aging mechanisms and data on epigenetic regulation of ontogenesis. Transposons may be the material bases of the epigenetic control system, their movements affect the differentiation of cells and can cause genomic instability. Control systems aimed at protecting against foreign DNA (splicing machine, microRNA processing) became the basis of regulatory networks of genomes underlying cell differentiation. Transposon sequences are the basis for non-coding RNAs that suppress the expression of the transposons themselves and protein-coding genes at the posttranscriptional level, as well as by altering the activity of methyltransferases and modifying the histone modification. Influence on transposons provides a basis for combating aging and age-associated pathologies. In particular, it is possible to influence the change in the length of telomeres, the origin of which is associated with retroelements, by regulating the activity of transposons.
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Affiliation(s)
- R N Mustafin
- Bashkir State University, 32, Zaki Validi str., Ufa, 450076, Russian Federation;
| | - E K Khusnutdinova
- Bashkir State University, 32, Zaki Validi str., Ufa, 450076, Russian Federation;
- Institute of Biochemistry and Genetics, Ufa Research Center, 71, Oktyabrya pr., Ufa, 450054, Russian Federation
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31
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Abstract
Despite often being classified as selfish or junk DNA, transposable elements (TEs) are a group of abundant genetic sequences that have a significant impact on mammalian development and genome regulation. In recent years, our understanding of how pre-existing TEs affect genome architecture, gene regulatory networks and protein function during mammalian embryogenesis has dramatically expanded. In addition, the mobilization of active TEs in selected cell types has been shown to generate genetic variation during development and in fully differentiated tissues. Importantly, the ongoing domestication and evolution of TEs appears to provide a rich source of regulatory elements, functional modules and genetic variation that fuels the evolution of mammalian developmental processes. Here, we review the functional impact that TEs exert on mammalian developmental processes and discuss how the somatic activity of TEs can influence gene regulatory networks.
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Affiliation(s)
- Jose L Garcia-Perez
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
- Department of Genomic Medicine, GENYO, Centre for Genomics & Oncology (Pfizer - University of Granada & Andalusian Regional Government), PTS Granada, Avda. de la Ilustración 114, Granada 18016, Spain
| | - Thomas J Widmann
- Department of Genomic Medicine, GENYO, Centre for Genomics & Oncology (Pfizer - University of Granada & Andalusian Regional Government), PTS Granada, Avda. de la Ilustración 114, Granada 18016, Spain
| | - Ian R Adams
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
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32
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Steige KA, Slotte T. Genomic legacies of the progenitors and the evolutionary consequences of allopolyploidy. Curr Opin Plant Biol 2016; 30:88-93. [PMID: 26943938 DOI: 10.1016/j.pbi.2016.02.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 02/13/2016] [Accepted: 02/15/2016] [Indexed: 06/05/2023]
Abstract
The formation of an allopolyploid species involves the merger of genomes with separate evolutionary histories and thereby different genomic legacies. Contrary to expectations from theory, genes from one are often lost preferentially in allopolyploids - there is biased fractionation. Here, we provide an overview of two ways in which the genomic legacies of the progenitors may impact the fate of duplicated genes in allopolyploids. Specifically, we discuss the role of homeolog expression biases in setting the stage for biased fractionation, and the evidence for transposable element silencing as a possible mechanism for homeolog expression biases. Finally, we highlight how differences between the progenitors with respect to accumulation of deleterious variation may affect trajectories of duplicate gene evolution in allopolyploids.
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Affiliation(s)
- Kim A Steige
- Department of Ecology and Genetics, Uppsala University, Sweden; Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden
| | - Tanja Slotte
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, Sweden.
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33
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Zavilgelsky GB, Kotova VY, Melkina OE, Balabanov VP, Mindlin SZ. [Proteolytic control of the antirestriction activity of Tn2l, Tn5053, Tn5045 Tn501 TN402 non-conjugative transposons]. Mol Biol (Mosk) 2015; 49:334-341. [PMID: 26065261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Conjugative plasmids and conjugative transposons contain the genes, which products specifically inhibit the type I restriction--modification systems. Here is shown that non-conjugative transposons Tn2l, Tn5053, Tn5045, Tn501, Tn402 partially inhibit the restriction activity of the type I restriction-modification endonuclease EcoKI (R2M2S1) in Escherichia coli cells K12 (the phenomenon of restriction alleviation, RA). Antirestriction activity of the transposons is determined by the MerR and ArdD proteins. Antirestriction activity of transposons is absent in mutants E. coli K12 clpX and clpP and is decreased in mutants E. coli K12 recA, recBC and dnaQ (mutD). Induction of the RA in response to the MerR and ArdD activities is consistent with the production of unmodified target sequences following DNA repair and DNA synthesis associated with recombination repair or replication errors. RA effect is determined by the ClpXP-dependent degradation of the endonuclease activity R subunit of EcoKI (R2M2S1).
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34
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Abstract
Asexual reproduction is usually considered as an evolutionary dead end, and difficulties for asexual lineages to adapt to a fluctuating environment are anticipated due to the lack of sufficient genetic plasticity. Yet, unlike their sexual congeners, mitotic parthenogenetic root-knot nematode species, Meloidogyne spp., are remarkably widespread and polyphagous, with the ability to parasitize most flowering plants. Although this may reflect in part the short-term stability of agricultural environments, the extreme parasitic success of these clonal species points them as an outstanding evolutionary paradox regarding current theories on the benefits of sex. The discovery that most of the genome of the clonal species M. incognita is composed of pairs of homologous but divergent segments that have presumably been evolving independently in the absence of sexual recombination has shed new light on this evolutionary paradox. Together with recent studies on other biological systems, including the closely related sexual species M. hapla and the ancient asexual bdelloid rotifers, this observation suggests that functional innovation could emerge from such a peculiar genome architecture, which may in turn account for the extreme adaptive capacities of these asexual parasites. Additionally, the higher proportion of transposable elements in M. incognita compared to M. hapla and other nematodes may also be responsible in part for genome plasticity in the absence of sexual reproduction. We foresee that ongoing sequencing efforts should lead soon to a genomic framework involving genetically diverse Meloidogyne species with various different reproductive modes. This will undoubtedly promote the entire genus as a unique and valuable model system to help deciphering the evolution of asexual reproduction in eukaryotes.
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Ayarpadikannan S, Lee HE, Han K, Kim HS. Transposable element-driven transcript diversification and its relevance to genetic disorders. Gene 2015; 558:187-94. [PMID: 25617522 DOI: 10.1016/j.gene.2015.01.039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 01/13/2015] [Accepted: 01/20/2015] [Indexed: 12/14/2022]
Abstract
The human genome project and subsequent gene annotation projects have shown that the human genome contains 22,000-25,000 functional genes. Therefore, it is believed that the diversity of protein repertoire is achieved by the alternative splicing (AS) mechanism. Transposable elements (TEs) are mobile in nature and can therefore alter their position in the genome. The insertion of TEs into a new gene region can result in AS of a particular transcript through various mechanisms, including intron retention, and alternative donor or acceptor splice sites. TE-derived AS is thought to have played a part in primate evolution and in hominid radiation. However, TE-derived AS or genetic instability may sometimes result in genetic disorders. For the past two decades, numerous studies have been performed on TEs and their role in genomes. Accumulating evidence shows that the term 'junk DNA', previously used for TEs is a misnomer. Recent research has indicated that TEs may have clinical potential. However, to explore the feasibility of using TEs in clinical practice, additional studies are required. This review summarizes the available literature on TE-derived AS, alternative promoter, and alternative polyadenylation. The review covers the effects of TEs on coding genes and their clinical implications, and provides our perspectives and directions for future research.
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Affiliation(s)
- Selvam Ayarpadikannan
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea
| | - Hee-Eun Lee
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea
| | - Kyudong Han
- Department of Nanobiomedical Science, WCU Research Center, Dankook University, Cheonan 330-714, Republic of Korea
| | - Heui-Soo Kim
- Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Republic of Korea.
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36
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Affiliation(s)
- Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel.
| | - Simon Barak
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel.
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37
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Leighton GO, Konnova TA, Idiyatullin B, Hurr SH, Zuev YF, Nesmelova IV. The folding of the specific DNA recognition subdomain of the sleeping beauty transposase is temperature-dependent and is required for its binding to the transposon DNA. PLoS One 2014; 9:e112114. [PMID: 25375127 PMCID: PMC4222973 DOI: 10.1371/journal.pone.0112114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 10/13/2014] [Indexed: 12/26/2022] Open
Abstract
The reaction of DNA transposition begins when the transposase enzyme binds to the transposon DNA. Sleeping Beauty is a member of the mariner family of DNA transposons. Although it is an important tool in genetic applications and has been adapted for human gene therapy, its molecular mechanism remains obscure. Here, we show that only the folded conformation of the specific DNA recognition subdomain of the Sleeping Beauty transposase, the PAI subdomain, binds to the transposon DNA. Furthermore, we show that the PAI subdomain is well folded at low temperatures, but the presence of unfolded conformation gradually increases at temperatures above 15°C, suggesting that the choice of temperature may be important for the optimal transposase activity. Overall, the results provide a molecular-level insight into the DNA recognition by the Sleeping Beauty transposase.
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Affiliation(s)
- Gage O. Leighton
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, United States of America
| | - Tatiana A. Konnova
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, United States of America
- Kazan Institute of Biochemistry and Biophysics, Kazan, Russian Federation
| | - Bulat Idiyatullin
- Kazan Institute of Biochemistry and Biophysics, Kazan, Russian Federation
| | - Sophia H. Hurr
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, United States of America
| | - Yuriy F. Zuev
- Kazan Institute of Biochemistry and Biophysics, Kazan, Russian Federation
| | - Irina V. Nesmelova
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, United States of America
- Center for Biomedical Engineering and Science, University of North Carolina, Charlotte, North Carolina, United States of America
- * E-mail:
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38
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Cui X, Cao X. Epigenetic regulation and functional exaptation of transposable elements in higher plants. Curr Opin Plant Biol 2014; 21:83-88. [PMID: 25061895 DOI: 10.1016/j.pbi.2014.07.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 06/23/2014] [Accepted: 07/02/2014] [Indexed: 05/06/2023]
Abstract
Transposable elements (TEs) are mobile genetic elements that can proliferate in their host genomes. Because of their robust amplification, TEs have long been considered 'selfish DNA', harmful insertions that can threaten host genome integrity. The idea of TEs as junk DNA comes from analysis of epigenetic silencing of their mobility in plants and animals. This idea contrasts with McClintock's characterization of TEs as 'controlling elements'. Emerging studies on the regulatory functions of TEs in plant genomes have updated McClintock's characterization, indicating exaptation of TEs for genetic regulation. In this review, we summarize recent progress in TE silencing, particularly in Arabidopsis and rice, and show that TEs provide an abundant, natural source of regulation for the host genome.
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Affiliation(s)
- Xiekui Cui
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiaofeng Cao
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
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39
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Zavigel'skiĭ GB, Kotova VI, Mel'kina OE, Pustovoĭt KS. [Antirestriction activity of the mercury resistance nonconjugative transposon Tn5053 is controlled by the protease ClpXP]. Genetika 2014; 50:1033-1039. [PMID: 25735133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
When transformed into Escherichia coli K12 strains, the mercury resistance transposon Tn5053@ exhibits high antirestriction activity against the EcoKI type I restriction and modification system. The products of the genes merR and ardD contribute to the antirestriction activity of Tn5053. The merR gene encodes the MerR protein, the transcription regulator of the mer operon genes. The ardD gene is responsible for ArdD protein synthesis and is located within the tni operon. In the following study, it was demonstrated that the antirestriction activity of the transposon Tn5053 is absent in E. coli K12 strains with the mutant genes clpX, clpP, and recA. The antirestriction effect of Tn5053 is not enhanced by 2-aminopurine. The Tn5053 antirestriction activity is not altered in E. coli K12 with the mutant dam gene; however, it is decreased in the E. coli K12 mutD. It is assumed that the activities of the MerR and ArdD proteins lead to the formation of a significant amount of unmodified DNA in the bacterial cell, causing the SOS-dependent reduction of the EcoKI (R2M2S) enzyme activity associated with ClpXP-induced proteolysis of the R-subuinit.
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40
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Kabelitz T, Kappel C, Henneberger K, Benke E, Nöh C, Bäurle I. eQTL mapping of transposon silencing reveals a position-dependent stable escape from epigenetic silencing and transposition of AtMu1 in the Arabidopsis lineage. Plant Cell 2014; 26:3261-71. [PMID: 25096782 PMCID: PMC4176438 DOI: 10.1105/tpc.114.128512] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/02/2014] [Accepted: 07/22/2014] [Indexed: 05/21/2023]
Abstract
Transposons are massively abundant in all eukaryotic genomes and are suppressed by epigenetic silencing. Transposon activity contributes to the evolution of species; however, it is unclear how much transposition-induced variation exists at a smaller scale and how transposons are targeted for silencing. Here, we exploited differential silencing of the AtMu1c transposon in the Arabidopsis thaliana accessions Columbia (Col) and Landsberg erecta (Ler). The difference persisted in hybrids and recombinant inbred lines and was mapped to a single expression quantitative trait locus within a 20-kb interval. In Ler only, this interval contained a previously unidentified copy of AtMu1c, which was inserted at the 3' end of a protein-coding gene and showed features of expressed genes. By contrast, AtMu1c(Col) was intergenic and associated with heterochromatic features. Furthermore, we identified widespread natural AtMu1c transposition from the analysis of over 200 accessions, which was not evident from alignments to the reference genome. AtMu1c expression was highest for insertions within 3' untranslated regions, suggesting that this location provides protection from silencing. Taken together, our results provide a species-wide view of the activity of one transposable element at unprecedented resolution, showing that AtMu1c transposed in the Arabidopsis lineage and that transposons can escape epigenetic silencing by inserting into specific genomic locations, such as the 3' end of genes.
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Affiliation(s)
- Tina Kabelitz
- Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| | - Christian Kappel
- Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| | - Kirstin Henneberger
- Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| | - Eileen Benke
- Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| | - Christiane Nöh
- Institute for Breeding Research on Agricultural Crops, Julius Kühn-Institute, Federal Research Centre for Cultivated Plants, 18190 Sanitz, Germany
| | - Isabel Bäurle
- Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
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Abstract
Our genome contains tens of thousands of long noncoding RNAs (lncRNAs), many of which are likely to have genetic regulatory functions. It has been proposed that lncRNA are organized into combinations of discrete functional domains, but the nature of these and their identification remain elusive. One class of sequence elements that is enriched in lncRNA is represented by transposable elements (TEs), repetitive mobile genetic sequences that have contributed widely to genome evolution through a process termed exaptation. Here, we link these two concepts by proposing that exonic TEs act as RNA domains that are essential for lncRNA function. We term such elements Repeat Insertion Domains of LncRNAs (RIDLs). A growing number of RIDLs have been experimentally defined, where TE-derived fragments of lncRNA act as RNA-, DNA-, and protein-binding domains. We propose that these reflect a more general phenomenon of exaptation during lncRNA evolution, where inserted TE sequences are repurposed as recognition sites for both protein and nucleic acids. We discuss a series of genomic screens that may be used in the future to systematically discover RIDLs. The RIDL hypothesis has the potential to explain how functional evolution can keep pace with the rapid gene evolution observed in lncRNA. More practically, TE maps may in the future be used to predict lncRNA function.
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Affiliation(s)
- Rory Johnson
- Centre for Genomic Regulation (CRG), 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
- Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), 08003 Barcelona, Spain
- Corresponding authorE-mail
| | - Roderic Guigó
- Centre for Genomic Regulation (CRG), 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
- Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), 08003 Barcelona, Spain
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42
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Bull L. Evolving functional and structural dynamism in coupled Boolean networks. Artif Life 2014; 20:441-455. [PMID: 24730764 DOI: 10.1162/artl_a_00137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This article uses a recently presented abstract, tunable Boolean regulatory network model to further explore aspects of mobile DNA, such as transposons. The significant role of mobile DNA in the evolution of natural systems is becoming increasingly clear. This article shows how dynamically controlling network node connectivity and function via transposon-inspired mechanisms can be selected for to significant degrees under coupled regulatory network scenarios, including when such changes are heritable. Simple multicellular and coevolutionary versions of the model are considered.
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43
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Grandaubert J, Balesdent MH, Rouxel T. [Transposable elements reshaping genomes and favouring the evolutionary and adaptive potential of fungal phytopathogens]. Biol Aujourdhui 2014; 207:277-290. [PMID: 24594576 DOI: 10.1051/jbio/2013026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Indexed: 06/03/2023]
Abstract
Phytopathogenic fungi are a major threat for global food security and show an extreme plasticity in pathogenicity behaviours. They often have a high adaptive potential allowing them to rapidly counteract the control methods used by men in agrosystems. In this paper, we evaluate the link between genome plasticity and adaptive potential using genomics and comparative genomics approaches. Our model is the evolutionary series Leptosphaeria maculans-Leptosphaeria biglobosa, encompassing five distinct entities, whose conspecificity or heterospecificity status is unclear, and which all are pathogens of cruciferous plants. They however differ by their host range and pathogenicity. Compared to other species of the species complex, the species best adapted to oilseed rape, L. maculans "brassicae", causing important losses in the crop, has a genome that was submitted to a recent and massive burst of transposition by a few families of transposable elements (TEs). Whether the genome invasion contributed to speciation is still unclear to-date but there is a coincidence between this burst of TEs and divergence between two species. This TE burst contributed to diversification of effector proteins and thus to generation of novel pathogenic specificities. In addition, the location of effector genes within genome regions enriched in TEs has direct consequences on adaptation to plant resistance and favours a multiplicity of mutation events allowing "breakdown" of resistance. These data are substantiated by other examples in the literature showing that fungi tend to have a "two-speed" genome, in which a plastic compartment enriched in TE host genes is involved in pathogenicity and adaptation to host.
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44
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Murray SM, Panis G, Fumeaux C, Viollier PH, Howard M. Computational and genetic reduction of a cell cycle to its simplest, primordial components. PLoS Biol 2013; 11:e1001749. [PMID: 24415923 PMCID: PMC3885167 DOI: 10.1371/journal.pbio.1001749] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 11/14/2013] [Indexed: 02/02/2023] Open
Abstract
What are the minimal requirements to sustain an asymmetric cell cycle? Here we use mathematical modelling and forward genetics to reduce an asymmetric cell cycle to its simplest, primordial components. In the Alphaproteobacterium Caulobacter crescentus, cell cycle progression is believed to be controlled by a cyclical genetic circuit comprising four essential master regulators. Unexpectedly, our in silico modelling predicted that one of these regulators, GcrA, is in fact dispensable. We confirmed this experimentally, finding that ΔgcrA cells are viable, but slow-growing and elongated, with the latter mostly due to an insufficiency of a key cell division protein. Furthermore, suppressor analysis showed that another cell cycle regulator, the methyltransferase CcrM, is similarly dispensable with simultaneous gcrA/ccrM disruption ameliorating the cytokinetic and growth defect of ΔgcrA cells. Within the Alphaproteobacteria, gcrA and ccrM are consistently present or absent together, rather than either gene being present alone, suggesting that gcrA/ccrM constitutes an independent, dispensable genetic module. Together our approaches unveil the essential elements of a primordial asymmetric cell cycle that should help illuminate more complex cell cycles.
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Affiliation(s)
- Seán M. Murray
- Computational and Systems Biology, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Gaël Panis
- Department of Microbiology & Molecular Medicine, Institute of Genetics & Genomics in Geneva (iGE3), Faculty of Medicine/CMU, University of Geneva, Geneva, Switzerland
| | - Coralie Fumeaux
- Department of Microbiology & Molecular Medicine, Institute of Genetics & Genomics in Geneva (iGE3), Faculty of Medicine/CMU, University of Geneva, Geneva, Switzerland
| | - Patrick H. Viollier
- Department of Microbiology & Molecular Medicine, Institute of Genetics & Genomics in Geneva (iGE3), Faculty of Medicine/CMU, University of Geneva, Geneva, Switzerland
- * E-mail: (P.H.V.); (M.H.)
| | - Martin Howard
- Computational and Systems Biology, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
- * E-mail: (P.H.V.); (M.H.)
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45
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De Cecco M, Criscione SW, Peterson AL, Neretti N, Sedivy JM, Kreiling JA. Transposable elements become active and mobile in the genomes of aging mammalian somatic tissues. Aging (Albany NY) 2013; 5:867-83. [PMID: 24323947 PMCID: PMC3883704 DOI: 10.18632/aging.100621] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 12/06/2013] [Indexed: 12/15/2022]
Abstract
Transposable elements (TEs) were discovered by Barbara McClintock in maize and have since been found to be ubiquitous in all living organisms. Transposition is mutagenic and organisms have evolved mechanisms to repress the activity of their endogenous TEs. Transposition in somatic cells is very low, but recent evidence suggests that it may be derepressed in some cases, such as cancer development. We have found that during normal aging several families of retrotransposable elements (RTEs) start being transcribed in mouse tissues. In advanced age the expression culminates in active transposition. These processes are counteracted by calorie restriction (CR), an intervention that slows down aging. Retrotransposition is also activated in age-associated, naturally occurring cancers in the mouse. We suggest that somatic retrotransposition is a hitherto unappreciated aging process. Mobilization of RTEs is likely to be an important contributor to the progressive dysfunction of aging cells.
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Affiliation(s)
- Marco De Cecco
- Department of Molecular Biology, Cell Biology and Biochemistry, Center for Genomics and Proteomics, Brown University, Providence, RI 02903, USA
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Grajevskaja V, Balciuniene J, Balciunas D. Chicken β-globin insulators fail to shield the nkx2.5 promoter from integration site effects in zebrafish. Mol Genet Genomics 2013; 288:717-25. [PMID: 24036575 PMCID: PMC4104600 DOI: 10.1007/s00438-013-0778-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 08/23/2013] [Indexed: 10/26/2022]
Abstract
Genetic lineage tracing and conditional mutagenesis are developmental genetics techniques reliant on precise tissue-specific expression of transgenes. In the mouse, high specificity is usually achieved by inserting the transgene into the locus of interest through homologous recombination in embryonic stem cells. In the zebrafish, DNA containing the transgenic construct is randomly integrated into the genome, usually through transposon-mediated transgenesis. Expression of such transgenes is affected by regulatory features surrounding the integration site from general accessibility of chromatin to tissue-specific enhancers. We tested if the 1.2 kb cHS4 insulators derived from the chicken β-globin locus can shield a transgene from chromosomal position effects in the zebrafish genome. As our test promoters, we used two different-length versions of the zebrafish nkx2.5. We found that flanking a transgenic construct by cHS4 insulation sequences leads to overall increase in the expression of nkx2.5:mRFP. However, we also observed a very high degree of variability of mRFP expression, indicating that cHS4 insulators fail to protect nkx2.5:mRFP from falling under the control of enhancers in the vicinity of integration site.
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Affiliation(s)
- Viktorija Grajevskaja
- Department of Biology, Temple University, Philadelphia, PA 19122, USA
- Department of Zoology, Faculty of Natural Sciences, Vilnius University, Vilnius, Lithuania
| | | | - Darius Balciunas
- Department of Biology, Temple University, Philadelphia, PA 19122, USA
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Llera-Herrera R, García-Gasca A, Abreu-Goodger C, Huvet A, Ibarra AM. Identification of male gametogenesis expressed genes from the scallop Nodipecten subnodosus by suppressive subtraction hybridization and pyrosequencing. PLoS One 2013; 8:e73176. [PMID: 24066034 PMCID: PMC3774672 DOI: 10.1371/journal.pone.0073176] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 07/17/2013] [Indexed: 01/01/2023] Open
Abstract
Despite the great advances in sequencing technologies, genomic and transcriptomic information for marine non-model species with ecological, evolutionary, and economical interest is still scarce. In this work we aimed to identify genes expressed during spermatogenesis in the functional hermaphrodite scallop Nodipecten subnodosus (Mollusca: Bivalvia: Pectinidae), with the purpose of obtaining a panel of genes that would allow for the study of differentially transcribed genes between diploid and triploid scallops in the context of meiotic arrest and reproductive sterility. Because our aim was to isolate genes involved in meiosis and other testis maturation-related processes, we generated suppressive subtractive hybridization libraries of testis vs. inactive gonad. We obtained 352 and 177 ESTs by clone sequencing, and using pyrosequencing (454-Roche) we maximized the identified ESTs to 34,276 reads. A total of 1,153 genes from the testis library had a blastx hit and GO annotation, including genes specific for meiosis, spermatogenesis, sex-differentiation, and transposable elements. Some of the identified meiosis genes function in chromosome pairing (scp2, scp3), recombination and DNA repair (dmc1, rad51, ccnb1ip1/hei10), and meiotic checkpoints (rad1, hormad1, dtl/cdt2). Gene expression analyses in different gametogenic stages in both sexual regions of the gonad of meiosis genes confirmed that the expression was specific or increased towards the maturing testis. Spermatogenesis genes included known testis-specific ones (kelch-10, shippo1, adad1), with some of these known to be associated to sterility. Sex differentiation genes included one of the most conserved genes at the bottom of the sex-determination cascade (dmrt1). Transcript from transposable elements, reverse transcriptase, and transposases in this library evidenced that transposition is an active process during spermatogenesis in N. subnodosus. In relation to the inactive library, we identified 833 transcripts with functional annotation related to activation of the transcription and translation machinery, as well as to germline control and maintenance.
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Affiliation(s)
- Raúl Llera-Herrera
- Aquaculture Genetics and Breeding Laboratory, Centro de Investigaciones Biológicas del Noroeste, La Paz, Baja California Sur, Mexico
| | | | - Cei Abreu-Goodger
- Laboratorio Nacional de Genómica para la Biodiversidad (Langebio), Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Irapuato, Guanajuato, Mexico
| | - Arnaud Huvet
- Laboratoire des Sciences de l'Environnement Marin, Institut Français de Recherche pour l'Exploitation de la Mer, (IFREMER), Centre de Bretagne, Plouzané, France
| | - Ana M. Ibarra
- Aquaculture Genetics and Breeding Laboratory, Centro de Investigaciones Biológicas del Noroeste, La Paz, Baja California Sur, Mexico
- * E-mail:
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Friedel RH, Friedel CC, Bonfert T, Shi R, Rad R, Soriano P. Clonal expansion analysis of transposon insertions by high-throughput sequencing identifies candidate cancer genes in a PiggyBac mutagenesis screen. PLoS One 2013; 8:e72338. [PMID: 23940809 PMCID: PMC3733837 DOI: 10.1371/journal.pone.0072338] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 07/08/2013] [Indexed: 11/18/2022] Open
Abstract
Somatic transposon mutagenesis in mice is an efficient strategy to investigate the genetic mechanisms of tumorigenesis. The identification of tumor driving transposon insertions traditionally requires the generation of large tumor cohorts to obtain information about common insertion sites. Tumor driving insertions are also characterized by their clonal expansion in tumor tissue, a phenomenon that is facilitated by the slow and evolving transformation process of transposon mutagenesis. We describe here an improved approach for the detection of tumor driving insertions that assesses the clonal expansion of insertions by quantifying the relative proportion of sequence reads obtained in individual tumors. To this end, we have developed a protocol for insertion site sequencing that utilizes acoustic shearing of tumor DNA and Illumina sequencing. We analyzed various solid tumors generated by PiggyBac mutagenesis and for each tumor >106 reads corresponding to >104 insertion sites were obtained. In each tumor, 9 to 25 insertions stood out by their enriched sequence read frequencies when compared to frequencies obtained from tail DNA controls. These enriched insertions are potential clonally expanded tumor driving insertions, and thus identify candidate cancer genes. The candidate cancer genes of our study comprised many established cancer genes, but also novel candidate genes such as Mastermind-like1 (Mamld1) and Diacylglycerolkinase delta (Dgkd). We show that clonal expansion analysis by high-throughput sequencing is a robust approach for the identification of candidate cancer genes in insertional mutagenesis screens on the level of individual tumors.
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Affiliation(s)
- Roland H Friedel
- Department of Neuroscience, Department of Developmental and Regenerative Biology, Department of Neurosurgery, Icahn School of Medicine at Mount, Sinai, New York, New York, United States of America.
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Xie W, Donohue RC, Birchler JA. Quantitatively increased somatic transposition of transposable elements in Drosophila strains compromised for RNAi. PLoS One 2013; 8:e72163. [PMID: 23940807 PMCID: PMC3733903 DOI: 10.1371/journal.pone.0072163] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 07/07/2013] [Indexed: 11/19/2022] Open
Abstract
In Drosophila melanogaster, small RNAs homologous to transposable elements (TEs) are of two types: piRNA (piwi-interacting RNA) with size 23-29nt and siRNA (small interfering RNA) with size 19-22nt. The siRNA pathway is suggested to silence TE activities in somatic tissues based on TE expression profiles, but direct evidence of transposition is lacking. Here we developed an efficient FISH (fluorescence in Situ hybridization) based method for polytene chromosomes from larval salivary glands to reveal new TE insertions. Analysis of the LTR-retrotransposon 297 and the non-LTR retroposon DOC shows that in the argonaut 2 (Ago2) and Dicer 2 (Dcr2) mutant strains, new transposition events are much more frequent than in heterozygous strains or wild type strains. The data demonstrate that the siRNA pathway represses TE transposition in somatic cells. Nevertheless, we found that loss of one functional copy of Ago2 or Dcr2 increases somatic transpositions of the elements at a lower level depending on the genetic background, suggesting a quantitative role for RNAi core components on mutation frequency.
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Affiliation(s)
- Weiwu Xie
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
| | - Ryan C. Donohue
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
| | - James A. Birchler
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
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Hayward A, Ghazal A, Andersson G, Andersson L, Jern P. ZBED evolution: repeated utilization of DNA transposons as regulators of diverse host functions. PLoS One 2013; 8:e59940. [PMID: 23533661 PMCID: PMC3606216 DOI: 10.1371/journal.pone.0059940] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 02/20/2013] [Indexed: 11/19/2022] Open
Abstract
ZBED genes originate from domesticated hAT DNA transposons and encode regulatory proteins of diverse function in vertebrates. Here we reveal the evolutionary relationship between ZBED genes and demonstrate that they are derived from at least two independent domestication events in jawed vertebrate ancestors. We show that ZBEDs form two monophyletic clades, one of which has expanded through several independent duplications in host lineages. Subsequent diversification of ZBED genes has facilitated regulation of multiple diverse fundamental functions. In contrast to known examples of transposable element exaptation, our results demonstrate a novel unprecedented capacity for the repeated utilization of a family of transposable element-derived protein domains sequestered as regulators during the evolution of diverse host gene functions in vertebrates. Specifically, ZBEDs have contributed to vertebrate regulatory innovation through the donation of modular DNA and protein interacting domains. We identify that C7ORF29, ZBED2, 3, 4, and ZBEDX form a monophyletic group together with ZBED6, that is distinct from ZBED1 genes. Furthermore, we show that ZBED5 is related to Buster DNA transposons and is phylogenetically separate from other ZBEDs. Our results offer new insights into the evolution of regulatory pathways, and suggest that DNA transposons have contributed to regulatory complexity during genome evolution in vertebrates.
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Affiliation(s)
- Alexander Hayward
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail: (AH); (PJ)
| | - Awaisa Ghazal
- Science for Life Laboratory, Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Göran Andersson
- Science for Life Laboratory, Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Leif Andersson
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- Science for Life Laboratory, Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Patric Jern
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail: (AH); (PJ)
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