1
|
Bastiaanssen C, Joo C. Small RNA-directed DNA elimination: the molecular mechanism and its potential for genome editing. RNA Biol 2021; 18:1540-1545. [PMID: 33530834 PMCID: PMC8583303 DOI: 10.1080/15476286.2021.1885208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Transposable elements have both detrimental and beneficial effects on their host genome. Tetrahymena is a unicellular eukaryote that deals with transposable elements in a unique way. It has a separate somatic and germline genome in two nuclei in a single cell. During sexual reproduction, a small RNA directed system compares the germline and somatic genome to identify transposable elements and related sequences. These are subsequently marked by heterochromatin and excised. In this Review, current knowledge of this system and the gaps therein are discussed. Additionally, the possibility to exploit the Tetrahymena machinery for genome editing and its advantages over the widely used CRISPR-Cas9 system will be explored. While the bacterial derived CRISPR-Cas9 has difficulty to access eukaryotic chromatin, Tetrahymena proteins are adept at acting in a chromatin context. Furthermore, Tetrahymena based gene therapy in humans might be a safer alternative to Cas9 because the latter can trigger an immune response.
Collapse
Affiliation(s)
- Carolien Bastiaanssen
- Department of BioNanoScience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Chirlmin Joo
- Department of BioNanoScience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| |
Collapse
|
2
|
Huang Y, Jiang L, Liu BY, Tan CF, Chen DH, Shen WH, Ruan Y. Evolution and conservation of polycomb repressive complex 1 core components and putative associated factors in the green lineage. BMC Genomics 2019; 20:533. [PMID: 31253095 PMCID: PMC6599366 DOI: 10.1186/s12864-019-5905-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 06/13/2019] [Indexed: 01/14/2023] Open
Abstract
Background Polycomb group (PcG) proteins play important roles in animal and plant development and stress response. Polycomb repressive complex 1 (PRC1) and PRC2 are the key epigenetic regulators of gene expression, and are involved in almost all developmental stages. PRC1 catalyzes H2A monoubiquitination resulting in transcriptional silencing or activation. The PRC1 components in the green lineage were identified and evolution and conservation was analyzed by bioinformatics techniques. RING Finger Protein 1 (RING1), B lymphoma Mo-MLV insertion region 1 homolog (BMI1), Like Heterochromatin Protein 1 (LHP1) and Embryonic Flower 1 (EMF1) are the PRC1 core components and Vernalization 1 (VRN1), VP1/ABI3-Like 1/2/3 (VAL1/2/3), Alfin-like 1–7 (AL1–7), Inhibitor of growth 1/2 (ING1/2), and Early Bolting in Short Days (EBS) / Short Life (SHL) are the associated factors. Results Each PRC1 subunit possesses special domain organizations, such as RING and the ring finger and WD40-associated ubiquitin-like (RAWUL) domains for RING1 and BMI1, chromatin organization modifier (CHROMO) and chromo shadow (ChSh) domains for LHP1, one or two B3 DNA binding domain(s) for VRN1, B3 and zf-CW domains for VAL1/2/3, Alfin and Plant HomeoDomain (PHD) domains for AL1–7, ING and PHD domains for ING1/2, Bromoadjacent homology (BAT) and PHD domains for EBS/SHL. Six new motifs are uncovered in EMF1. The PRC1 core components RING1 and BMI1, and the associated factors VAL1/2/3, AL1–7, ING1/2, and EBS/SHL exist from alga to higher plants, whereas LHP1 only occurs in higher plants. EMF1 and VRN1 are present only in eudicots. PRC1 components undergo duplication in the plant evolution. Most of plants carry the homologous core component LHP1, the associated factor EMF1, and several homologs in RING1, BMI1, VRN1, AL1–7, ING1/2/3, and EBS/SHL. Cabbage, cotton, poplar, orange and maize often exhibit more gene copies than other species. Domain organization analysis shows that duplicated gene functions may be of diverse. Conclusions The PRC1 core components RING1 and BMI1, and the associated factors VAL1/2/3, AL1–7, ING1/2, and EBS/SHL originate from algae. The core component LHP1 is from moss and the associated factors EMF1 and VRN1 are from dicotyledon. PRC1 components are of functional redundancy and diversity in evolution. Electronic supplementary material The online version of this article (10.1186/s12864-019-5905-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Yong Huang
- Key Laboratory of Crop Epigenetic Regulation and Development in Hunan Province, Hunan Agricultural University, Changsha, 410128, China.,International Associated Laboratory of CNRS-FU-HAU on Plant Epigenome Research, Hunan Agricultural University, Changsha, 410128, China.,Key Laboratory of Plant Genetics and Molecular Biology of Education Department of Hunan Province, Hunan Agricultural University, Changsha, 410128, China
| | - Ling Jiang
- Key Laboratory of Crop Epigenetic Regulation and Development in Hunan Province, Hunan Agricultural University, Changsha, 410128, China.,International Associated Laboratory of CNRS-FU-HAU on Plant Epigenome Research, Hunan Agricultural University, Changsha, 410128, China.,Key Laboratory of Plant Genetics and Molecular Biology of Education Department of Hunan Province, Hunan Agricultural University, Changsha, 410128, China
| | - Bo-Yu Liu
- Key Laboratory of Crop Epigenetic Regulation and Development in Hunan Province, Hunan Agricultural University, Changsha, 410128, China.,International Associated Laboratory of CNRS-FU-HAU on Plant Epigenome Research, Hunan Agricultural University, Changsha, 410128, China.,Key Laboratory of Plant Genetics and Molecular Biology of Education Department of Hunan Province, Hunan Agricultural University, Changsha, 410128, China
| | - Cheng-Fang Tan
- Key Laboratory of Crop Epigenetic Regulation and Development in Hunan Province, Hunan Agricultural University, Changsha, 410128, China.,International Associated Laboratory of CNRS-FU-HAU on Plant Epigenome Research, Hunan Agricultural University, Changsha, 410128, China.,Key Laboratory of Plant Genetics and Molecular Biology of Education Department of Hunan Province, Hunan Agricultural University, Changsha, 410128, China
| | - Dong-Hong Chen
- State Key Laboratory of Subtropical Silviculture, SFGA Engineering Research Center for Dendrobium catenatum (D. officinale), Zhejiang A&F University, Hangzhou, 311300, China
| | - Wen-Hui Shen
- International Associated Laboratory of CNRS-FU-HAU on Plant Epigenome Research, Hunan Agricultural University, Changsha, 410128, China.,Institut de Biologie Mole'culaire des Plantes du CNRS, Universite' de Strasbourg, 12 rue du Ge'ne'ralZimmer, 67084, Strasbourg Cedex, France
| | - Ying Ruan
- Key Laboratory of Crop Epigenetic Regulation and Development in Hunan Province, Hunan Agricultural University, Changsha, 410128, China. .,International Associated Laboratory of CNRS-FU-HAU on Plant Epigenome Research, Hunan Agricultural University, Changsha, 410128, China. .,Key Laboratory of Plant Genetics and Molecular Biology of Education Department of Hunan Province, Hunan Agricultural University, Changsha, 410128, China.
| |
Collapse
|
3
|
Noto T, Mochizuki K. Whats, hows and whys of programmed DNA elimination in Tetrahymena. Open Biol 2018; 7:rsob.170172. [PMID: 29021213 PMCID: PMC5666084 DOI: 10.1098/rsob.170172] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/12/2017] [Indexed: 12/20/2022] Open
Abstract
Programmed genome rearrangements in ciliates provide fascinating examples of flexible epigenetic genome regulations and important insights into the interaction between transposable elements (TEs) and host genomes. DNA elimination in Tetrahymena thermophila removes approximately 12 000 internal eliminated sequences (IESs), which correspond to one-third of the genome, when the somatic macronucleus (MAC) differentiates from the germline micronucleus (MIC). More than half of the IESs, many of which show high similarity to TEs, are targeted for elimination in cis by the small RNA-mediated genome comparison of the MIC to the MAC. Other IESs are targeted for elimination in trans by the same small RNAs through repetitive sequences. Furthermore, the small RNA–heterochromatin feedback loop ensures robust DNA elimination. Here, we review an updated picture of the DNA elimination mechanism, discuss the physiological and evolutionary roles of DNA elimination, and outline the key questions that remain unanswered.
Collapse
Affiliation(s)
- Tomoko Noto
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, Montpellier, France
| | - Kazufumi Mochizuki
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, Montpellier, France
| |
Collapse
|